- Issue #10181: New memoryview implementation fixes multiple ownership

  and lifetime issues of dynamically allocated Py_buffer members (#9990)
  as well as crashes (#8305, #7433). Many new features have been added
  (See whatsnew/3.3), and the documentation has been updated extensively.
  The ndarray test object from _testbuffer.c implements all aspects of
  PEP-3118, so further development towards the complete implementation
  of the PEP can proceed in a test-driven manner.

  Thanks to Nick Coghlan, Antoine Pitrou and Pauli Virtanen for review
  and many ideas.

- Issue #12834: Fix incorrect results of memoryview.tobytes() for
  non-contiguous arrays.

- Issue #5231: Introduce memoryview.cast() method that allows changing
  format and shape without making a copy of the underlying memory.

24 files changed, 9844 insertions, 1004 deletions

diff --git a/Doc/c-api/buffer.rst b/Doc/c-api/buffer.rst
index d98ece3e98..2d199922f2 100644
--- a/Doc/c-api/buffer.rst
+++ b/Doc/c-api/buffer.rst
@@ -7,6 +7,7 @@ Buffer Protocol
 
 .. sectionauthor:: Greg Stein <gstein@lyra.org>
 .. sectionauthor:: Benjamin Peterson
+.. sectionauthor:: Stefan Krah
 
 
 .. index::
@@ -20,7 +21,7 @@ as image processing or numeric analysis.
 
 While each of these types have their own semantics, they share the common
 characteristic of being backed by a possibly large memory buffer.  It is
-then desireable, in some situations, to access that buffer directly and
+then desirable, in some situations, to access that buffer directly and
 without intermediate copying.
 
 Python provides such a facility at the C level in the form of the *buffer
@@ -60,8 +61,10 @@ isn't needed anymore.  Failure to do so could lead to various issues such as
 resource leaks.
 
 
-The buffer structure
-====================
+.. _buffer-structure:
+
+Buffer structure
+================
 
 Buffer structures (or simply "buffers") are useful as a way to expose the
 binary data from another object to the Python programmer.  They can also be
@@ -81,246 +84,400 @@ can be created.
 
 .. c:type:: Py_buffer
 
-   .. c:member:: void *buf
+   .. c:member:: void \*obj
+
+      A new reference to the exporting object or *NULL*. The reference is owned
+      by the consumer and automatically decremented and set to *NULL* by
+      :c:func:`PyBuffer_Release`.
+
+      For temporary buffers that are wrapped by :c:func:`PyMemoryView_FromBuffer`
+      this field must be *NULL*.
 
-      A pointer to the start of the memory for the object.
+   .. c:member:: void \*buf
+
+      A pointer to the start of the logical structure described by the buffer
+      fields. This can be any location within the underlying physical memory
+      block of the exporter. For example, with negative :c:member:`~Py_buffer.strides`
+      the value may point to the end of the memory block.
+
+      For contiguous arrays, the value points to the beginning of the memory
+      block.
 
    .. c:member:: Py_ssize_t len
-      :noindex:
 
-      The total length of the memory in bytes.
+      ``product(shape) * itemsize``. For contiguous arrays, this is the length
+      of the underlying memory block. For non-contiguous arrays, it is the length
+      that the logical structure would have if it were copied to a contiguous
+      representation.
+
+      Accessing ``((char *)buf)[0] up to ((char *)buf)[len-1]`` is only valid
+      if the buffer has been obtained by a request that guarantees contiguity. In
+      most cases such a request will be :c:macro:`PyBUF_SIMPLE` or :c:macro:`PyBUF_WRITABLE`.
 
    .. c:member:: int readonly
 
-      An indicator of whether the buffer is read only.
+      An indicator of whether the buffer is read-only. This field is controlled
+      by the :c:macro:`PyBUF_WRITABLE` flag.
+
+   .. c:member:: Py_ssize_t itemsize
+
+      Item size in bytes of a single element. Same as the value of :func:`struct.calcsize`
+      called on non-NULL :c:member:`~Py_buffer.format` values.
+
+      Important exception: If a consumer requests a buffer without the
+      :c:macro:`PyBUF_FORMAT` flag, :c:member:`~Py_Buffer.format` will
+      be set to  *NULL*,  but :c:member:`~Py_buffer.itemsize` still has
+      the value for the original format.
+
+      If :c:member:`~Py_Buffer.shape` is present, the equality
+      ``product(shape) * itemsize == len`` still holds and the consumer
+      can use :c:member:`~Py_buffer.itemsize` to navigate the buffer.
+
+      If :c:member:`~Py_Buffer.shape` is *NULL* as a result of a :c:macro:`PyBUF_SIMPLE`
+      or a :c:macro:`PyBUF_WRITABLE` request, the consumer must disregard
+      :c:member:`~Py_buffer.itemsize` and assume ``itemsize == 1``.
 
-   .. c:member:: const char *format
-      :noindex:
+   .. c:member:: const char \*format
 
-      A *NULL* terminated string in :mod:`struct` module style syntax giving
-      the contents of the elements available through the buffer.  If this is
-      *NULL*, ``"B"`` (unsigned bytes) is assumed.
+      A *NUL* terminated string in :mod:`struct` module style syntax describing
+      the contents of a single item. If this is *NULL*, ``"B"`` (unsigned bytes)
+      is assumed.
+
+      This field is controlled by the :c:macro:`PyBUF_FORMAT` flag.
 
    .. c:member:: int ndim
 
-      The number of dimensions the memory represents as a multi-dimensional
-      array.  If it is 0, :c:data:`strides` and :c:data:`suboffsets` must be
-      *NULL*.
-
-   .. c:member:: Py_ssize_t *shape
-
-      An array of :c:type:`Py_ssize_t`\s the length of :c:data:`ndim` giving the
-      shape of the memory as a multi-dimensional array.  Note that
-      ``((*shape)[0] * ... * (*shape)[ndims-1])*itemsize`` should be equal to
-      :c:data:`len`.
-
-   .. c:member:: Py_ssize_t *strides
-
-      An array of :c:type:`Py_ssize_t`\s the length of :c:data:`ndim` giving the
-      number of bytes to skip to get to a new element in each dimension.
-
-   .. c:member:: Py_ssize_t *suboffsets
-
-      An array of :c:type:`Py_ssize_t`\s the length of :c:data:`ndim`.  If these
-      suboffset numbers are greater than or equal to 0, then the value stored
-      along the indicated dimension is a pointer and the suboffset value
-      dictates how many bytes to add to the pointer after de-referencing. A
-      suboffset value that it negative indicates that no de-referencing should
-      occur (striding in a contiguous memory block).
-
-      Here is a function that returns a pointer to the element in an N-D array
-      pointed to by an N-dimensional index when there are both non-NULL strides
-      and suboffsets::
-
-          void *get_item_pointer(int ndim, void *buf, Py_ssize_t *strides,
-              Py_ssize_t *suboffsets, Py_ssize_t *indices) {
-              char *pointer = (char*)buf;
-              int i;
-              for (i = 0; i < ndim; i++) {
-                  pointer += strides[i] * indices[i];
-                  if (suboffsets[i] >=0 ) {
-                      pointer = *((char**)pointer) + suboffsets[i];
-                  }
-              }
-              return (void*)pointer;
-           }
+      The number of dimensions the memory represents as an n-dimensional array.
+      If it is 0, :c:member:`~Py_Buffer.buf` points to a single item representing
+      a scalar. In this case, :c:member:`~Py_buffer.shape`, :c:member:`~Py_buffer.strides`
+      and :c:member:`~Py_buffer.suboffsets` MUST be *NULL*.
 
+      The macro :c:macro:`PyBUF_MAX_NDIM` limits the maximum number of dimensions
+      to 64. Exporters MUST respect this limit, consumers of multi-dimensional
+      buffers SHOULD be able to handle up to :c:macro:`PyBUF_MAX_NDIM` dimensions.
 
-   .. c:member:: Py_ssize_t itemsize
+   .. c:member:: Py_ssize_t \*shape
+
+      An array of :c:type:`Py_ssize_t` of length :c:member:`~Py_buffer.ndim`
+      indicating the shape of the memory as an n-dimensional array. Note that
+      ``shape[0] * ... * shape[ndim-1] * itemsize`` MUST be equal to
+      :c:member:`~Py_buffer.len`.
+
+      Shape values are restricted to ``shape[n] >= 0``. The case
+      ``shape[n] == 0`` requires special attention. See `complex arrays`_
+      for further information.
+
+      The shape array is read-only for the consumer.
+
+   .. c:member:: Py_ssize_t \*strides
+
+      An array of :c:type:`Py_ssize_t` of length :c:member:`~Py_buffer.ndim`
+      giving the number of bytes to skip to get to a new element in each
+      dimension.
+
+      Stride values can be any integer. For regular arrays, strides are
+      usually positive, but a consumer MUST be able to handle the case
+      ``strides[n] <= 0``. See `complex arrays`_ for further information.
+
+      The strides array is read-only for the consumer.
+
+   .. c:member:: Py_ssize_t \*suboffsets
+
+      An array of :c:type:`Py_ssize_t` of length :c:member:`~Py_buffer.ndim`.
+      If ``suboffsets[n] >= 0``, the values stored along the nth dimension are
+      pointers and the suboffset value dictates how many bytes to add to each
+      pointer after de-referencing. A suboffset value that is negative
+      indicates that no de-referencing should occur (striding in a contiguous
+      memory block).
 
-      This is a storage for the itemsize (in bytes) of each element of the
-      shared memory. It is technically un-necessary as it can be obtained
-      using :c:func:`PyBuffer_SizeFromFormat`, however an exporter may know
-      this information without parsing the format string and it is necessary
-      to know the itemsize for proper interpretation of striding. Therefore,
-      storing it is more convenient and faster.
+      This type of array representation is used by the Python Imaging Library
+      (PIL). See `complex arrays`_ for further information how to access elements
+      of such an array.
 
-   .. c:member:: void *internal
+      The suboffsets array is read-only for the consumer.
+
+   .. c:member:: void \*internal
 
       This is for use internally by the exporting object. For example, this
       might be re-cast as an integer by the exporter and used to store flags
       about whether or not the shape, strides, and suboffsets arrays must be
-      freed when the buffer is released. The consumer should never alter this
+      freed when the buffer is released. The consumer MUST NOT alter this
       value.
 
+.. _buffer-request-types:
 
-Buffer-related functions
-========================
+Buffer request types
+====================
 
+Buffers are usually obtained by sending a buffer request to an exporting
+object via :c:func:`PyObject_GetBuffer`. Since the complexity of the logical
+structure of the memory can vary drastically, the consumer uses the *flags*
+argument to specify the exact buffer type it can handle.
 
-.. c:function:: int PyObject_CheckBuffer(PyObject *obj)
+All :c:data:`Py_buffer` fields are unambiguously defined by the request
+type.
+
+request-independent fields
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+The following fields are not influenced by *flags* and must always be filled in
+with the correct values: :c:member:`~Py_buffer.obj`, :c:member:`~Py_buffer.buf`,
+:c:member:`~Py_buffer.len`, :c:member:`~Py_buffer.itemsize`, :c:member:`~Py_buffer.ndim`.
 
-   Return 1 if *obj* supports the buffer interface otherwise 0.  When 1 is
-   returned, it doesn't guarantee that :c:func:`PyObject_GetBuffer` will
-   succeed.
 
+readonly, format
+~~~~~~~~~~~~~~~~
 
-.. c:function:: int PyObject_GetBuffer(PyObject *obj, Py_buffer *view, int flags)
+   .. c:macro:: PyBUF_WRITABLE
 
-      Export a view over some internal data from the target object *obj*.
-      *obj* must not be NULL, and *view* must point to an existing
-      :c:type:`Py_buffer` structure allocated by the caller (most uses of
-      this function will simply declare a local variable of type
-      :c:type:`Py_buffer`).  The *flags* argument is a bit field indicating
-      what kind of buffer is requested.  The buffer interface allows
-      for complicated memory layout possibilities; however, some callers
-      won't want to handle all the complexity and instead request a simple
-      view of the target object (using :c:macro:`PyBUF_SIMPLE` for a read-only
-      view and :c:macro:`PyBUF_WRITABLE` for a read-write view).
+      Controls the :c:member:`~Py_buffer.readonly` field. If set, the exporter
+      MUST provide a writable buffer or else report failure. Otherwise, the
+      exporter MAY provide either a read-only or writable buffer, but the choice
+      MUST be consistent for all consumers.
 
-      Some exporters may not be able to share memory in every possible way and
-      may need to raise errors to signal to some consumers that something is
-      just not possible. These errors should be a :exc:`BufferError` unless
-      there is another error that is actually causing the problem. The
-      exporter can use flags information to simplify how much of the
-      :c:data:`Py_buffer` structure is filled in with non-default values and/or
-      raise an error if the object can't support a simpler view of its memory.
+   .. c:macro:: PyBUF_FORMAT
 
-      On success, 0 is returned and the *view* structure is filled with useful
-      values.  On error, -1 is returned and an exception is raised; the *view*
-      is left in an undefined state.
+      Controls the :c:member:`~Py_buffer.format` field. If set, this field MUST
+      be filled in correctly. Otherwise, this field MUST be *NULL*.
 
-      The following are the possible values to the *flags* arguments.
 
-      .. c:macro:: PyBUF_SIMPLE
+:c:macro:`PyBUF_WRITABLE` can be \|'d to any of the flags in the next section.
+Since :c:macro:`PyBUF_SIMPLE` is defined as 0, :c:macro:`PyBUF_WRITABLE`
+can be used as a stand-alone flag to request a simple writable buffer.
 
-         This is the default flag.  The returned buffer exposes a read-only
-         memory area.  The format of data is assumed to be raw unsigned bytes,
-         without any particular structure.  This is a "stand-alone" flag
-         constant.  It never needs to be '|'d to the others.  The exporter will
-         raise an error if it cannot provide such a contiguous buffer of bytes.
+:c:macro:`PyBUF_FORMAT` can be \|'d to any of the flags except :c:macro:`PyBUF_SIMPLE`.
+The latter already implies format ``B`` (unsigned bytes).
 
-      .. c:macro:: PyBUF_WRITABLE
 
-         Like :c:macro:`PyBUF_SIMPLE`, but the returned buffer is writable.  If
-         the exporter doesn't support writable buffers, an error is raised.
+shape, strides, suboffsets
+~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-      .. c:macro:: PyBUF_STRIDES
+The flags that control the logical structure of the memory are listed
+in decreasing order of complexity. Note that each flag contains all bits
+of the flags below it.
 
-         This implies :c:macro:`PyBUF_ND`.  The returned buffer must provide
-         strides information (i.e. the strides cannot be NULL).  This would be
-         used when the consumer can handle strided, discontiguous arrays.
-         Handling strides automatically assumes you can handle shape.  The
-         exporter can raise an error if a strided representation of the data is
-         not possible (i.e. without the suboffsets).
 
-      .. c:macro:: PyBUF_ND
++-----------------------------+-------+---------+------------+
+|  Request                    | shape | strides | suboffsets |
++=============================+=======+=========+============+
+| .. c:macro:: PyBUF_INDIRECT |  yes  |   yes   | if needed  |
++-----------------------------+-------+---------+------------+
+| .. c:macro:: PyBUF_STRIDES  |  yes  |   yes   |    NULL    |
++-----------------------------+-------+---------+------------+
+| .. c:macro:: PyBUF_ND       |  yes  |   NULL  |    NULL    |
++-----------------------------+-------+---------+------------+
+| .. c:macro:: PyBUF_SIMPLE   |  NULL |   NULL  |    NULL    |
++-----------------------------+-------+---------+------------+
 
-         The returned buffer must provide shape information.  The memory will be
-         assumed C-style contiguous (last dimension varies the fastest).  The
-         exporter may raise an error if it cannot provide this kind of
-         contiguous buffer.  If this is not given then shape will be *NULL*.
 
-      .. c:macro:: PyBUF_C_CONTIGUOUS
-                  PyBUF_F_CONTIGUOUS
-                  PyBUF_ANY_CONTIGUOUS
+contiguity requests
+~~~~~~~~~~~~~~~~~~~
 
-         These flags indicate that the contiguity returned buffer must be
-         respectively, C-contiguous (last dimension varies the fastest), Fortran
-         contiguous (first dimension varies the fastest) or either one.  All of
-         these flags imply :c:macro:`PyBUF_STRIDES` and guarantee that the
-         strides buffer info structure will be filled in correctly.
+C or Fortran contiguity can be explicitly requested, with and without stride
+information. Without stride information, the buffer must be C-contiguous.
 
-      .. c:macro:: PyBUF_INDIRECT
++-----------------------------------+-------+---------+------------+--------+
+|  Request                          | shape | strides | suboffsets | contig |
++===================================+=======+=========+============+========+
+| .. c:macro:: PyBUF_C_CONTIGUOUS   |  yes  |   yes   |    NULL    |   C    |
++-----------------------------------+-------+---------+------------+--------+
+| .. c:macro:: PyBUF_F_CONTIGUOUS   |  yes  |   yes   |    NULL    |   F    |
++-----------------------------------+-------+---------+------------+--------+
+| .. c:macro:: PyBUF_ANY_CONTIGUOUS |  yes  |   yes   |    NULL    | C or F |
++-----------------------------------+-------+---------+------------+--------+
+| .. c:macro:: PyBUF_ND             |  yes  |   NULL  |    NULL    |   C    |
++-----------------------------------+-------+---------+------------+--------+
 
-         This flag indicates the returned buffer must have suboffsets
-         information (which can be NULL if no suboffsets are needed).  This can
-         be used when the consumer can handle indirect array referencing implied
-         by these suboffsets. This implies :c:macro:`PyBUF_STRIDES`.
 
-      .. c:macro:: PyBUF_FORMAT
+compound requests
+~~~~~~~~~~~~~~~~~
 
-         The returned buffer must have true format information if this flag is
-         provided.  This would be used when the consumer is going to be checking
-         for what 'kind' of data is actually stored.  An exporter should always
-         be able to provide this information if requested.  If format is not
-         explicitly requested then the format must be returned as *NULL* (which
-         means ``'B'``, or unsigned bytes).
+All possible requests are fully defined by some combination of the flags in
+the previous section. For convenience, the buffer protocol provides frequently
+used combinations as single flags.
 
-      .. c:macro:: PyBUF_STRIDED
+In the following table *U* stands for undefined contiguity. The consumer would
+have to call :c:func:`PyBuffer_IsContiguous` to determine contiguity.
 
-         This is equivalent to ``(PyBUF_STRIDES | PyBUF_WRITABLE)``.
 
-      .. c:macro:: PyBUF_STRIDED_RO
 
-         This is equivalent to ``(PyBUF_STRIDES)``.
++-------------------------------+-------+---------+------------+--------+----------+--------+
+|  Request                      | shape | strides | suboffsets | contig | readonly | format |
++===============================+=======+=========+============+========+==========+========+
+| .. c:macro:: PyBUF_FULL       |  yes  |   yes   | if needed  |   U    |     0    |  yes   |
++-------------------------------+-------+---------+------------+--------+----------+--------+
+| .. c:macro:: PyBUF_FULL_RO    |  yes  |   yes   | if needed  |   U    |  1 or 0  |  yes   |
++-------------------------------+-------+---------+------------+--------+----------+--------+
+| .. c:macro:: PyBUF_RECORDS    |  yes  |   yes   |    NULL    |   U    |     0    |  yes   |
++-------------------------------+-------+---------+------------+--------+----------+--------+
+| .. c:macro:: PyBUF_RECORDS_RO |  yes  |   yes   |    NULL    |   U    |  1 or 0  |  yes   |
++-------------------------------+-------+---------+------------+--------+----------+--------+
+| .. c:macro:: PyBUF_STRIDED    |  yes  |   yes   |    NULL    |   U    |     0    |  NULL  |
++-------------------------------+-------+---------+------------+--------+----------+--------+
+| .. c:macro:: PyBUF_STRIDED_RO |  yes  |   yes   |    NULL    |   U    |  1 or 0  |  NULL  |
++-------------------------------+-------+---------+------------+--------+----------+--------+
+| .. c:macro:: PyBUF_CONTIG     |  yes  |   NULL  |    NULL    |   C    |     0    |  NULL  |
++-------------------------------+-------+---------+------------+--------+----------+--------+
+| .. c:macro:: PyBUF_CONTIG_RO  |  yes  |   NULL  |    NULL    |   C    |  1 or 0  |  NULL  |
++-------------------------------+-------+---------+------------+--------+----------+--------+
 
-      .. c:macro:: PyBUF_RECORDS
 
-         This is equivalent to ``(PyBUF_STRIDES | PyBUF_FORMAT |
-         PyBUF_WRITABLE)``.
+Complex arrays
+==============
 
-      .. c:macro:: PyBUF_RECORDS_RO
+NumPy-style: shape and strides
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The logical structure of NumPy-style arrays is defined by :c:member:`~Py_buffer.itemsize`,
+:c:member:`~Py_buffer.ndim`, :c:member:`~Py_buffer.shape` and :c:member:`~Py_buffer.strides`.
+
+If ``ndim == 0``, the memory location pointed to by :c:member:`~Py_buffer.buf` is
+interpreted as a scalar of size :c:member:`~Py_buffer.itemsize`. In that case,
+both :c:member:`~Py_buffer.shape` and :c:member:`~Py_buffer.strides` are *NULL*.
+
+If :c:member:`~Py_buffer.strides` is *NULL*, the array is interpreted as
+a standard n-dimensional C-array. Otherwise, the consumer must access an
+n-dimensional array as follows:
+
+   ``ptr = (char *)buf + indices[0] * strides[0] + ... + indices[n-1] * strides[n-1]``
+   ``item = *((typeof(item) *)ptr);``
+
+
+As noted above, :c:member:`~Py_buffer.buf` can point to any location within
+the actual memory block. An exporter can check the validity of a buffer with
+this function:
+
+.. code-block:: python
+
+   def verify_structure(memlen, itemsize, ndim, shape, strides, offset):
+       """Verify that the parameters represent a valid array within
+          the bounds of the allocated memory:
+              char *mem: start of the physical memory block
+              memlen: length of the physical memory block
+              offset: (char *)buf - mem
+       """
+       if offset % itemsize:
+           return False
+       if offset < 0 or offset+itemsize > memlen:
+           return False
+       if any(v % itemsize for v in strides):
+           return False
+
+       if ndim <= 0:
+           return ndim == 0 and not shape and not strides
+       if 0 in shape:
+           return True
+
+       imin = sum(strides[j]*(shape[j]-1) for j in range(ndim)
+                  if strides[j] <= 0)
+       imax = sum(strides[j]*(shape[j]-1) for j in range(ndim)
+                  if strides[j] > 0)
+
+       return 0 <= offset+imin and offset+imax+itemsize <= memlen
+
+
+PIL-style: shape, strides and suboffsets
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In addition to the regular items, PIL-style arrays can contain pointers
+that must be followed in order to get to the next element in a dimension.
+For example, the regular three-dimensional C-array ``char v[2][2][3]`` can
+also be viewed as an array of 2 pointers to 2 two-dimensional arrays:
+``char (*v[2])[2][3]``. In suboffsets representation, those two pointers
+can be embedded at the start of :c:member:`~Py_buffer.buf`, pointing
+to two ``char x[2][3]`` arrays that can be located anywhere in memory.
+
+
+Here is a function that returns a pointer to the element in an N-D array
+pointed to by an N-dimensional index when there are both non-NULL strides
+and suboffsets::
+
+   void *get_item_pointer(int ndim, void *buf, Py_ssize_t *strides,
+                          Py_ssize_t *suboffsets, Py_ssize_t *indices) {
+       char *pointer = (char*)buf;
+       int i;
+       for (i = 0; i < ndim; i++) {
+           pointer += strides[i] * indices[i];
+           if (suboffsets[i] >=0 ) {
+               pointer = *((char**)pointer) + suboffsets[i];
+           }
+       }
+       return (void*)pointer;
+   }
 
-         This is equivalent to ``(PyBUF_STRIDES | PyBUF_FORMAT)``.
 
-      .. c:macro:: PyBUF_FULL
+Buffer-related functions
+========================
 
-         This is equivalent to ``(PyBUF_INDIRECT | PyBUF_FORMAT |
-         PyBUF_WRITABLE)``.
+.. c:function:: int PyObject_CheckBuffer(PyObject *obj)
 
-      .. c:macro:: PyBUF_FULL_RO
+   Return 1 if *obj* supports the buffer interface otherwise 0.  When 1 is
+   returned, it doesn't guarantee that :c:func:`PyObject_GetBuffer` will
+   succeed.
 
-         This is equivalent to ``(PyBUF_INDIRECT | PyBUF_FORMAT)``.
 
-      .. c:macro:: PyBUF_CONTIG
+.. c:function:: int PyObject_GetBuffer(PyObject *exporter, Py_buffer *view, int flags)
 
-         This is equivalent to ``(PyBUF_ND | PyBUF_WRITABLE)``.
+   Send a request to *exporter* to fill in *view* as specified by  *flags*.
+   If the exporter cannot provide a buffer of the exact type, it MUST raise
+   :c:data:`PyExc_BufferError`, set :c:member:`view->obj` to *NULL* and
+   return -1.
 
-      .. c:macro:: PyBUF_CONTIG_RO
+   On success, fill in *view*, set :c:member:`view->obj` to a new reference
+   to *exporter* and return 0.
 
-         This is equivalent to ``(PyBUF_ND)``.
+   Successful calls to :c:func:`PyObject_GetBuffer` must be paired with calls
+   to :c:func:`PyBuffer_Release`, similar to :c:func:`malloc` and :c:func:`free`.
+   Thus, after the consumer is done with the buffer, :c:func:`PyBuffer_Release`
+   must be called exactly once.
 
 
 .. c:function:: void PyBuffer_Release(Py_buffer *view)
 
-   Release the buffer *view*.  This should be called when the buffer is no
-   longer being used as it may free memory from it.
+   Release the buffer *view* and decrement the reference count for
+   :c:member:`view->obj`. This function MUST be called when the buffer
+   is no longer being used, otherwise reference leaks may occur.
+
+   It is an error to call this function on a buffer that was not obtained via
+   :c:func:`PyObject_GetBuffer`.
 
 
 .. c:function:: Py_ssize_t PyBuffer_SizeFromFormat(const char *)
 
-   Return the implied :c:data:`~Py_buffer.itemsize` from the struct-stype
-   :c:data:`~Py_buffer.format`.
+   Return the implied :c:data:`~Py_buffer.itemsize` from :c:data:`~Py_buffer.format`.
+   This function is not yet implemented.
 
 
-.. c:function:: int PyBuffer_IsContiguous(Py_buffer *view, char fortran)
+.. c:function:: int PyBuffer_IsContiguous(Py_buffer *view, char order)
 
-   Return 1 if the memory defined by the *view* is C-style (*fortran* is
-   ``'C'``) or Fortran-style (*fortran* is ``'F'``) contiguous or either one
-   (*fortran* is ``'A'``).  Return 0 otherwise.
+   Return 1 if the memory defined by the *view* is C-style (*order* is
+   ``'C'``) or Fortran-style (*order* is ``'F'``) contiguous or either one
+   (*order* is ``'A'``).  Return 0 otherwise.
 
 
-.. c:function:: void PyBuffer_FillContiguousStrides(int ndim, Py_ssize_t *shape, Py_ssize_t *strides, Py_ssize_t itemsize, char fortran)
+.. c:function:: void PyBuffer_FillContiguousStrides(int ndim, Py_ssize_t *shape, Py_ssize_t *strides, Py_ssize_t itemsize, char order)
 
    Fill the *strides* array with byte-strides of a contiguous (C-style if
-   *fortran* is ``'C'`` or Fortran-style if *fortran* is ``'F'``) array of the
+   *order* is ``'C'`` or Fortran-style if *order* is ``'F'``) array of the
    given shape with the given number of bytes per element.
 
 
-.. c:function:: int PyBuffer_FillInfo(Py_buffer *view, PyObject *obj, void *buf, Py_ssize_t len, int readonly, int infoflags)
+.. c:function:: int PyBuffer_FillInfo(Py_buffer *view, PyObject *exporter, void *buf, Py_ssize_t len, int readonly, int flags)
+
+   Handle buffer requests for an exporter that wants to expose *buf* of size *len*
+   with writability set according to *readonly*. *buf* is interpreted as a sequence
+   of unsigned bytes.
+
+   The *flags* argument indicates the request type. This function always fills in
+   *view* as specified by flags, unless *buf* has been designated as read-only
+   and :c:macro:`PyBUF_WRITABLE` is set in *flags*.
+
+   On success, set :c:member:`view->obj` to a new reference to *exporter* and
+   return 0. Otherwise, raise :c:data:`PyExc_BufferError`, set
+   :c:member:`view->obj` to *NULL* and return -1;
+
+   If this function is used as part of a :ref:`getbufferproc <buffer-structs>`,
+   *exporter* MUST be set to the exporting object. Otherwise, *exporter* MUST
+   be NULL.
+
 
-   Fill in a buffer-info structure, *view*, correctly for an exporter that can
-   only share a contiguous chunk of memory of "unsigned bytes" of the given
-   length.  Return 0 on success and -1 (with raising an error) on error.
 
diff --git a/Doc/c-api/memoryview.rst b/Doc/c-api/memoryview.rst
index 6b49cdf70a..ef039753af 100644
--- a/Doc/c-api/memoryview.rst
+++ b/Doc/c-api/memoryview.rst
@@ -17,16 +17,19 @@ any other object.
 
    Create a memoryview object from an object that provides the buffer interface.
    If *obj* supports writable buffer exports, the memoryview object will be
-   readable and writable, otherwise it will be read-only.
+   read/write, otherwise it may be either read-only or read/write at the
+   discretion of the exporter.
 
+.. c:function:: PyObject *PyMemoryView_FromMemory(char *mem, Py_ssize_t size, int flags)
+
+   Create a memoryview object using *mem* as the underlying buffer.
+   *flags* can be one of :c:macro:`PyBUF_READ` or :c:macro:`PyBUF_WRITE`.
 
 .. c:function:: PyObject *PyMemoryView_FromBuffer(Py_buffer *view)
 
    Create a memoryview object wrapping the given buffer structure *view*.
-   The memoryview object then owns the buffer represented by *view*, which
-   means you shouldn't try to call :c:func:`PyBuffer_Release` yourself: it
-   will be done on deallocation of the memoryview object.
-
+   For simple byte buffers, :c:func:`PyMemoryView_FromMemory` is the preferred
+   function.
 
 .. c:function:: PyObject *PyMemoryView_GetContiguous(PyObject *obj, int buffertype, char order)
 
@@ -43,10 +46,16 @@ any other object.
    currently allowed to create subclasses of :class:`memoryview`.
 
 
-.. c:function:: Py_buffer *PyMemoryView_GET_BUFFER(PyObject *obj)
+.. c:function:: Py_buffer *PyMemoryView_GET_BUFFER(PyObject *mview)
+
+   Return a pointer to the memoryview's private copy of the exporter's buffer.
+   *mview* **must** be a memoryview instance; this macro doesn't check its type,
+   you must do it yourself or you will risk crashes.
+
+.. c:function:: Py_buffer *PyMemoryView_GET_BASE(PyObject *mview)
 
-   Return a pointer to the buffer structure wrapped by the given
-   memoryview object.  The object **must** be a memoryview instance;
-   this macro doesn't check its type, you must do it yourself or you
-   will risk crashes.
+   Return either a pointer to the exporting object that the memoryview is based
+   on or *NULL* if the memoryview has been created by one of the functions
+   :c:func:`PyMemoryView_FromMemory` or :c:func:`PyMemoryView_FromBuffer`.
+   *mview* **must** be a memoryview instance.
 
diff --git a/Doc/c-api/typeobj.rst b/Doc/c-api/typeobj.rst
index 68ca9adaa9..b15d927719 100644
--- a/Doc/c-api/typeobj.rst
+++ b/Doc/c-api/typeobj.rst
@@ -1198,46 +1198,74 @@ Buffer Object Structures
 
 .. sectionauthor:: Greg J. Stein <greg@lyra.org>
 .. sectionauthor:: Benjamin Peterson
+.. sectionauthor:: Stefan Krah
 
+.. c:type:: PyBufferProcs
 
-The :ref:`buffer interface <bufferobjects>` exports a model where an object can expose its internal
-data.
+   This structure holds pointers to the functions required by the
+   :ref:`Buffer protocol <bufferobjects>`. The protocol defines how
+   an exporter object can expose its internal data to consumer objects.
 
-If an object does not export the buffer interface, then its :attr:`tp_as_buffer`
-member in the :c:type:`PyTypeObject` structure should be *NULL*.  Otherwise, the
-:attr:`tp_as_buffer` will point to a :c:type:`PyBufferProcs` structure.
+.. c:member:: getbufferproc PyBufferProcs.bf_getbuffer
 
+   The signature of this function is::
 
-.. c:type:: PyBufferProcs
+       int (PyObject *exporter, Py_buffer *view, int flags);
+
+   Handle a request to *exporter* to fill in *view* as specified by *flags*.
+   A standard implementation of this function will take these steps:
+
+   - Check if the request can be met. If not, raise :c:data:`PyExc_BufferError`,
+     set :c:data:`view->obj` to *NULL* and return -1.
+
+   - Fill in the requested fields.
+
+   - Increment an internal counter for the number of exports.
+
+   - Set :c:data:`view->obj` to *exporter* and increment :c:data:`view->obj`.
+
+   - Return 0.
+
+   The individual fields of *view* are described in section
+   :ref:`Buffer structure <buffer-structure>`, the rules how an exporter
+   must react to specific requests are in section
+   :ref:`Buffer request types <buffer-request-types>`.
+
+   All memory pointed to in the :c:type:`Py_buffer` structure belongs to
+   the exporter and must remain valid until there are no consumers left.
+   :c:member:`~Py_buffer.shape`, :c:member:`~Py_buffer.strides`,
+   :c:member:`~Py_buffer.suboffsets` and :c:member:`~Py_buffer.internal`
+   are read-only for the consumer.
+
+   :c:func:`PyBuffer_FillInfo` provides an easy way of exposing a simple
+   bytes buffer while dealing correctly with all request types.
+
+   :c:func:`PyObject_GetBuffer` is the interface for the consumer that
+   wraps this function.
+
+.. c:member:: releasebufferproc PyBufferProcs.bf_releasebuffer
+
+   The signature of this function is::
+
+       void (PyObject *exporter, Py_buffer *view);
 
-   Structure used to hold the function pointers which define an implementation of
-   the buffer protocol.
+   Handle a request to release the resources of the buffer. If no resources
+   need to be released, this field may be *NULL*. A standard implementation
+   of this function will take these steps:
 
-   .. c:member:: getbufferproc bf_getbuffer
+   - Decrement an internal counter for the number of exports.
 
-      This should fill a :c:type:`Py_buffer` with the necessary data for
-      exporting the type.  The signature of :data:`getbufferproc` is ``int
-      (PyObject *obj, Py_buffer *view, int flags)``.  *obj* is the object to
-      export, *view* is the :c:type:`Py_buffer` struct to fill, and *flags* gives
-      the conditions the caller wants the memory under.  (See
-      :c:func:`PyObject_GetBuffer` for all flags.)  :c:member:`bf_getbuffer` is
-      responsible for filling *view* with the appropriate information.
-      (:c:func:`PyBuffer_FillView` can be used in simple cases.)  See
-      :c:type:`Py_buffer`\s docs for what needs to be filled in.
+   - If the counter is 0, free all memory associated with *view*.
 
+   The exporter MUST use the :c:member:`~Py_buffer.internal` field to keep
+   track of buffer-specific resources (if present). This field is guaranteed
+   to remain constant, while a consumer MAY pass a copy of the original buffer
+   as the *view* argument.
 
-   .. c:member:: releasebufferproc bf_releasebuffer
 
-      This should release the resources of the buffer.  The signature of
-      :c:data:`releasebufferproc` is ``void (PyObject *obj, Py_buffer *view)``.
-      If the :c:data:`bf_releasebuffer` function is not provided (i.e. it is
-      *NULL*), then it does not ever need to be called.
+   This function MUST NOT decrement :c:data:`view->obj`, since that is
+   done automatically in :c:func:`PyBuffer_Release`.
 
-      The exporter of the buffer interface must make sure that any memory
-      pointed to in the :c:type:`Py_buffer` structure remains valid until
-      releasebuffer is called.  Exporters will need to define a
-      :c:data:`bf_releasebuffer` function if they can re-allocate their memory,
-      strides, shape, suboffsets, or format variables which they might share
-      through the struct bufferinfo.
 
-      See :c:func:`PyBuffer_Release`.
+   :c:func:`PyBuffer_Release` is the interface for the consumer that
+   wraps this function.
diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst
index a07be4f91f..183b2f78fc 100644
--- a/Doc/library/stdtypes.rst
+++ b/Doc/library/stdtypes.rst
@@ -2377,7 +2377,7 @@ memoryview type
 
 :class:`memoryview` objects allow Python code to access the internal data
 of an object that supports the :ref:`buffer protocol <bufferobjects>` without
-copying.  Memory is generally interpreted as simple bytes.
+copying.
 
 .. class:: memoryview(obj)
 
@@ -2391,52 +2391,88 @@ copying.  Memory is generally interpreted as simple bytes.
    is a single byte, but other types such as :class:`array.array` may have
    bigger elements.
 
-   ``len(view)`` returns the total number of elements in the memoryview,
-   *view*.  The :class:`~memoryview.itemsize` attribute will give you the
+   ``len(view)`` is equal to the length of :class:`~memoryview.tolist`.
+   If ``view.ndim = 0``, the length is 1. If ``view.ndim = 1``, the length
+   is equal to the number of elements in the view. For higher dimensions,
+   the length is equal to the length of the nested list representation of
+   the view. The :class:`~memoryview.itemsize` attribute will give you the
    number of bytes in a single element.
 
-   A :class:`memoryview` supports slicing to expose its data.  Taking a single
-   index will return a single element as a :class:`bytes` object.  Full
-   slicing will result in a subview::
+   A :class:`memoryview` supports slicing to expose its data. If
+   :class:`~memoryview.format` is one of the native format specifiers
+   from the :mod:`struct` module, indexing will return a single element
+   with the correct type. Full slicing will result in a subview::
+
+    >>> v = memoryview(b'abcefg')
+    >>> v[1]
+    98
+    >>> v[-1]
+    103
+    >>> v[1:4]
+    <memory at 0x7f3ddc9f4350>
+    >>> bytes(v[1:4])
+    b'bce'
+
+   Other native formats::
+
+      >>> import array
+      >>> a = array.array('l', [-11111111, 22222222, -33333333, 44444444])
+      >>> a[0]
+      -11111111
+      >>> a[-1]
+      44444444
+      >>> a[2:3].tolist()
+      [-33333333]
+      >>> a[::2].tolist()
+      [-11111111, -33333333]
+      >>> a[::-1].tolist()
+      [44444444, -33333333, 22222222, -11111111]
 
-      >>> v = memoryview(b'abcefg')
-      >>> v[1]
-      b'b'
-      >>> v[-1]
-      b'g'
-      >>> v[1:4]
-      <memory at 0x77ab28>
-      >>> bytes(v[1:4])
-      b'bce'
-
-   If the object the memoryview is over supports changing its data, the
-   memoryview supports slice assignment::
+   .. versionadded:: 3.3
+
+   If the underlying object is writable, the memoryview supports slice
+   assignment. Resizing is not allowed::
 
       >>> data = bytearray(b'abcefg')
       >>> v = memoryview(data)
       >>> v.readonly
       False
-      >>> v[0] = b'z'
+      >>> v[0] = ord(b'z')
       >>> data
       bytearray(b'zbcefg')
       >>> v[1:4] = b'123'
       >>> data
       bytearray(b'z123fg')
-      >>> v[2] = b'spam'
+      >>> v[2:3] = b'spam'
       Traceback (most recent call last):
-        File "<stdin>", line 1, in <module>
-      ValueError: cannot modify size of memoryview object
-
-   Notice how the size of the memoryview object cannot be changed.
+      File "<stdin>", line 1, in <module>
+      ValueError: memoryview assignment: lvalue and rvalue have different structures
+      >>> v[2:6] = b'spam'
+      >>> data
+      bytearray(b'z1spam')
 
-   Memoryviews of hashable (read-only) types are also hashable and their
-   hash value matches the corresponding bytes object::
+   Memoryviews of hashable (read-only) types are also hashable. The hash
+   is defined as ``hash(m) == hash(m.tobytes())``::
 
       >>> v = memoryview(b'abcefg')
       >>> hash(v) == hash(b'abcefg')
       True
       >>> hash(v[2:4]) == hash(b'ce')
       True
+      >>> hash(v[::-2]) == hash(b'abcefg'[::-2])
+      True
+
+   Hashing of multi-dimensional objects is supported::
+
+      >>> buf = bytes(list(range(12)))
+      >>> x = memoryview(buf)
+      >>> y = x.cast('B', shape=[2,2,3])
+      >>> x.tolist()
+      [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
+      >>> y.tolist()
+      [[[0, 1, 2], [3, 4, 5]], [[6, 7, 8], [9, 10, 11]]]
+      >>> hash(x) == hash(y) == hash(y.tobytes())
+      True
 
    .. versionchanged:: 3.3
       Memoryview objects are now hashable.
@@ -2455,12 +2491,20 @@ copying.  Memory is generally interpreted as simple bytes.
          >>> bytes(m)
          b'abc'
 
+      For non-contiguous arrays the result is equal to the flattened list
+      representation with all elements converted to bytes.
+
    .. method:: tolist()
 
-      Return the data in the buffer as a list of integers. ::
+      Return the data in the buffer as a list of elements. ::
 
          >>> memoryview(b'abc').tolist()
          [97, 98, 99]
+         >>> import array
+         >>> a = array.array('d', [1.1, 2.2, 3.3])
+         >>> m = memoryview(a)
+         >>> m.tolist()
+         [1.1, 2.2, 3.3]
 
    .. method:: release()
 
@@ -2487,7 +2531,7 @@ copying.  Memory is generally interpreted as simple bytes.
          >>> with memoryview(b'abc') as m:
          ...     m[0]
          ...
-         b'a'
+         97
          >>> m[0]
          Traceback (most recent call last):
            File "<stdin>", line 1, in <module>
@@ -2495,45 +2539,219 @@ copying.  Memory is generally interpreted as simple bytes.
 
       .. versionadded:: 3.2
 
+   .. method:: cast(format[, shape])
+
+      Cast a memoryview to a new format or shape. *shape* defaults to
+      ``[byte_length//new_itemsize]``, which means that the result view
+      will be one-dimensional. The return value is a new memoryview, but
+      the buffer itself is not copied. Supported casts are 1D -> C-contiguous
+      and C-contiguous -> 1D. One of the formats must be a byte format
+      ('B', 'b' or 'c'). The byte length of the result must be the same
+      as the original length.
+
+      Cast 1D/long to 1D/unsigned bytes::
+
+         >>> import array
+         >>> a = array.array('l', [1,2,3])
+         >>> x = memoryview(a)
+         >>> x.format
+         'l'
+         >>> x.itemsize
+         8
+         >>> len(x)
+         3
+         >>> x.nbytes
+         24
+         >>> y = x.cast('B')
+         >>> y.format
+         'B'
+         >>> y.itemsize
+         1
+         >>> len(y)
+         24
+         >>> y.nbytes
+         24
+
+      Cast 1D/unsigned bytes to 1D/char::
+
+         >>> b = bytearray(b'zyz')
+         >>> x = memoryview(b)
+         >>> x[0] = b'a'
+         Traceback (most recent call last):
+           File "<stdin>", line 1, in <module>
+         ValueError: memoryview: invalid value for format "B"
+         >>> y = x.cast('c')
+         >>> y[0] = b'a'
+         >>> b
+         bytearray(b'ayz')
+
+      Cast 1D/bytes to 3D/ints to 1D/signed char::
+
+         >>> import struct
+         >>> buf = struct.pack("i"*12, *list(range(12)))
+         >>> x = memoryview(buf)
+         >>> y = x.cast('i', shape=[2,2,3])
+         >>> y.tolist()
+         [[[0, 1, 2], [3, 4, 5]], [[6, 7, 8], [9, 10, 11]]]
+         >>> y.format
+         'i'
+         >>> y.itemsize
+         4
+         >>> len(y)
+         2
+         >>> y.nbytes
+         48
+         >>> z = y.cast('b')
+         >>> z.format
+         'b'
+         >>> z.itemsize
+         1
+         >>> len(z)
+         48
+         >>> z.nbytes
+         48
+
+      Cast 1D/unsigned char to to 2D/unsigned long::
+
+         >>> buf = struct.pack("L"*6, *list(range(6)))
+         >>> x = memoryview(buf)
+         >>> y = x.cast('L', shape=[2,3])
+         >>> len(y)
+         2
+         >>> y.nbytes
+         48
+         >>> y.tolist()
+         [[0, 1, 2], [3, 4, 5]]
+
+      .. versionadded:: 3.3
+
    There are also several readonly attributes available:
 
+   .. attribute:: obj
+
+      The underlying object of the memoryview::
+
+         >>> b  = bytearray(b'xyz')
+         >>> m = memoryview(b)
+         >>> m.obj is b
+         True
+
+      .. versionadded:: 3.3
+
+   .. attribute:: nbytes
+
+      ``nbytes == product(shape) * itemsize == len(m.tobytes())``. This is
+      the amount of space in bytes that the array would use in a contiguous
+      representation. It is not necessarily equal to len(m)::
+
+         >>> import array
+         >>> a = array.array('i', [1,2,3,4,5])
+         >>> m = memoryview(a)
+         >>> len(m)
+         5
+         >>> m.nbytes
+         20
+         >>> y = m[::2]
+         >>> len(y)
+         3
+         >>> y.nbytes
+         12
+         >>> len(y.tobytes())
+         12
+
+      Multi-dimensional arrays::
+
+         >>> import struct
+         >>> buf = struct.pack("d"*12, *[1.5*x for x in range(12)])
+         >>> x = memoryview(buf)
+         >>> y = x.cast('d', shape=[3,4])
+         >>> y.tolist()
+         [[0.0, 1.5, 3.0, 4.5], [6.0, 7.5, 9.0, 10.5], [12.0, 13.5, 15.0, 16.5]]
+         >>> len(y)
+         3
+         >>> y.nbytes
+         96
+
+      .. versionadded:: 3.3
+
+   .. attribute:: readonly
+
+      A bool indicating whether the memory is read only.
+
    .. attribute:: format
 
       A string containing the format (in :mod:`struct` module style) for each
-      element in the view.  This defaults to ``'B'``, a simple bytestring.
+      element in the view. A memoryview can be created from exporters with
+      arbitrary format strings, but some methods (e.g. :meth:`tolist`) are
+      restricted to native single element formats. Special care must be taken
+      when comparing memoryviews. Since comparisons are required to return a
+      value for ``==`` and ``!=``, two memoryviews referencing the same
+      exporter can compare as not-equal if the exporter's format is not
+      understood::
+
+         >>> from ctypes import BigEndianStructure, c_long
+         >>> class BEPoint(BigEndianStructure):
+         ...     _fields_ = [("x", c_long), ("y", c_long)]
+         ...
+         >>> point = BEPoint(100, 200)
+         >>> a = memoryview(point)
+         >>> b = memoryview(point)
+         >>> a == b
+         False
+         >>> a.tolist()
+         Traceback (most recent call last):
+           File "<stdin>", line 1, in <module>
+         NotImplementedError: memoryview: unsupported format T{>l:x:>l:y:}
 
    .. attribute:: itemsize
 
       The size in bytes of each element of the memoryview::
 
-         >>> m = memoryview(array.array('H', [1,2,3]))
+         >>> import array, struct
+         >>> m = memoryview(array.array('H', [32000, 32001, 32002]))
          >>> m.itemsize
          2
          >>> m[0]
-         b'\x01\x00'
-         >>> len(m[0]) == m.itemsize
+         32000
+         >>> struct.calcsize('H') == m.itemsize
          True
 
-   .. attribute:: shape
-
-      A tuple of integers the length of :attr:`ndim` giving the shape of the
-      memory as a N-dimensional array.
-
    .. attribute:: ndim
 
       An integer indicating how many dimensions of a multi-dimensional array the
       memory represents.
 
+   .. attribute:: shape
+
+      A tuple of integers the length of :attr:`ndim` giving the shape of the
+      memory as a N-dimensional array.
+
    .. attribute:: strides
 
       A tuple of integers the length of :attr:`ndim` giving the size in bytes to
       access each element for each dimension of the array.
 
-   .. attribute:: readonly
+   .. attribute:: suboffsets
 
-      A bool indicating whether the memory is read only.
+      Used internally for PIL-style arrays. The value is informational only.
+
+   .. attribute:: c_contiguous
+
+      A bool indicating whether the memory is C-contiguous.
+
+      .. versionadded:: 3.3
+
+   .. attribute:: f_contiguous
+
+      A bool indicating whether the memory is Fortran contiguous.
+
+      .. versionadded:: 3.3
+
+   .. attribute:: contiguous
+
+      A bool indicating whether the memory is contiguous.
 
-   .. memoryview.suboffsets isn't documented because it only seems useful for C
+      .. versionadded:: 3.3
 
 
 .. _typecontextmanager:
diff --git a/Doc/whatsnew/3.3.rst b/Doc/whatsnew/3.3.rst
index 20e2914bc0..560331f39b 100644
--- a/Doc/whatsnew/3.3.rst
+++ b/Doc/whatsnew/3.3.rst
@@ -49,6 +49,62 @@
 This article explains the new features in Python 3.3, compared to 3.2.
 
 
+.. _pep-3118:
+
+PEP 3118: New memoryview implementation and buffer protocol documentation
+=========================================================================
+
+:issue:`10181` - memoryview bug fixes and features.
+  Written by Stefan Krah.
+
+The new memoryview implementation comprehensively fixes all ownership and
+lifetime issues of dynamically allocated fields in the Py_buffer struct
+that led to multiple crash reports. Additionally, several functions that
+crashed or returned incorrect results for non-contiguous or multi-dimensional
+input have been fixed.
+
+The memoryview object now has a PEP-3118 compliant getbufferproc()
+that checks the consumer's request type. Many new features have been
+added, most of them work in full generality for non-contiguous arrays
+and arrays with suboffsets.
+
+The documentation has been updated, clearly spelling out responsibilities
+for both exporters and consumers. Buffer request flags are grouped into
+basic and compound flags. The memory layout of non-contiguous and
+multi-dimensional NumPy-style arrays is explained.
+
+Features
+--------
+
+* All native single character format specifiers in struct module syntax
+  (optionally prefixed with '@') are now supported.
+
+* With some restrictions, the cast() method allows changing of format and
+  shape of C-contiguous arrays.
+
+* Multi-dimensional list representations are supported for any array type.
+
+* Multi-dimensional comparisons are supported for any array type.
+
+* All array types are hashable if the exporting object is hashable
+  and the view is read-only.
+
+* Arbitrary slicing of any 1-D arrays type is supported. For example, it
+  is now possible to reverse a memoryview in O(1) by using a negative step.
+
+API changes
+-----------
+
+* The maximum number of dimensions is officially limited to 64.
+
+* The representation of empty shape, strides and suboffsets is now
+  an empty tuple instead of None.
+
+* Accessing a memoryview element with format 'B' (unsigned bytes)
+  now returns an integer (in accordance with the struct module syntax).
+  For returning a bytes object the view must be cast to 'c' first.
+
+
 .. _pep-393:
 
 PEP 393: Flexible String Representation
diff --git a/Include/abstract.h b/Include/abstract.h
index 3946ec5b38..abb996ff1a 100644
--- a/Include/abstract.h
+++ b/Include/abstract.h
@@ -559,7 +559,7 @@ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
     /* Copy the data from the src buffer to the buffer of destination
      */
 
-     PyAPI_FUNC(int) PyBuffer_IsContiguous(Py_buffer *view, char fort);
+     PyAPI_FUNC(int) PyBuffer_IsContiguous(const Py_buffer *view, char fort);
 
 
      PyAPI_FUNC(void) PyBuffer_FillContiguousStrides(int ndims,
diff --git a/Include/memoryobject.h b/Include/memoryobject.h
index aff5d997f2..4ac6f6525c 100644
--- a/Include/memoryobject.h
+++ b/Include/memoryobject.h
@@ -6,70 +6,64 @@
 extern "C" {
 #endif
 
+#ifndef Py_LIMITED_API
+PyAPI_DATA(PyTypeObject) _PyManagedBuffer_Type;
+#endif
 PyAPI_DATA(PyTypeObject) PyMemoryView_Type;
 
 #define PyMemoryView_Check(op) (Py_TYPE(op) == &PyMemoryView_Type)
 
 #ifndef Py_LIMITED_API
-/* Get a pointer to the underlying Py_buffer of a memoryview object. */
+/* Get a pointer to the memoryview's private copy of the exporter's buffer. */
 #define PyMemoryView_GET_BUFFER(op) (&((PyMemoryViewObject *)(op))->view)
-/* Get a pointer to the PyObject from which originates a memoryview object. */
+/* Get a pointer to the exporting object (this may be NULL!). */
 #define PyMemoryView_GET_BASE(op) (((PyMemoryViewObject *)(op))->view.obj)
 #endif
 
-
-PyAPI_FUNC(PyObject *) PyMemoryView_GetContiguous(PyObject *base, 
-						  int buffertype, 
-						  char fort);
-
-    /* Return a contiguous chunk of memory representing the buffer
-       from an object in a memory view object.  If a copy is made then the
-       base object for the memory view will be a *new* bytes object. 
-       
-       Otherwise, the base-object will be the object itself and no 
-       data-copying will be done. 
-
-       The buffertype argument can be PyBUF_READ, PyBUF_WRITE,
-       PyBUF_SHADOW to determine whether the returned buffer
-       should be READONLY, WRITABLE, or set to update the
-       original buffer if a copy must be made.  If buffertype is
-       PyBUF_WRITE and the buffer is not contiguous an error will
-       be raised.  In this circumstance, the user can use
-       PyBUF_SHADOW to ensure that a a writable temporary
-       contiguous buffer is returned.  The contents of this
-       contiguous buffer will be copied back into the original
-       object after the memoryview object is deleted as long as
-       the original object is writable and allows setting an
-       exclusive write lock. If this is not allowed by the
-       original object, then a BufferError is raised.
-       
-       If the object is multi-dimensional and if fortran is 'F',
-       the first dimension of the underlying array will vary the
-       fastest in the buffer.  If fortran is 'C', then the last
-       dimension will vary the fastest (C-style contiguous).  If
-       fortran is 'A', then it does not matter and you will get
-       whatever the object decides is more efficient.  
-
-       A new reference is returned that must be DECREF'd when finished.
-    */
-
 PyAPI_FUNC(PyObject *) PyMemoryView_FromObject(PyObject *base);
-
+PyAPI_FUNC(PyObject *) PyMemoryView_FromMemory(char *mem, Py_ssize_t size,
+                                               int flags);
 #ifndef Py_LIMITED_API
 PyAPI_FUNC(PyObject *) PyMemoryView_FromBuffer(Py_buffer *info);
-    /* create new if bufptr is NULL 
-        will be a new bytesobject in base */
 #endif
+PyAPI_FUNC(PyObject *) PyMemoryView_GetContiguous(PyObject *base,
+                                                  int buffertype,
+                                                  char order);
 
 
-/* The struct is declared here so that macros can work, but it shouldn't
-   be considered public. Don't access those fields directly, use the macros
+/* The structs are declared here so that macros can work, but they shouldn't
+   be considered public. Don't access their fields directly, use the macros
    and functions instead! */
 #ifndef Py_LIMITED_API
+#define _Py_MANAGED_BUFFER_RELEASED    0x001  /* access to exporter blocked */
+#define _Py_MANAGED_BUFFER_FREE_FORMAT 0x002  /* free format */
 typedef struct {
     PyObject_HEAD
-    Py_buffer view;
-    Py_hash_t hash;
+    int flags;          /* state flags */
+    Py_ssize_t exports; /* number of direct memoryview exports */
+    Py_buffer master; /* snapshot buffer obtained from the original exporter */
+} _PyManagedBufferObject;
+
+
+/* static storage used for casting between formats */
+#define _Py_MEMORYVIEW_MAX_FORMAT 3 /* must be >= 3 */
+
+/* memoryview state flags */
+#define _Py_MEMORYVIEW_RELEASED    0x001  /* access to master buffer blocked */
+#define _Py_MEMORYVIEW_C           0x002  /* C-contiguous layout */
+#define _Py_MEMORYVIEW_FORTRAN     0x004  /* Fortran contiguous layout */
+#define _Py_MEMORYVIEW_SCALAR      0x008  /* scalar: ndim = 0 */
+#define _Py_MEMORYVIEW_PIL         0x010  /* PIL-style layout */
+
+typedef struct {
+    PyObject_VAR_HEAD
+    _PyManagedBufferObject *mbuf; /* managed buffer */
+    Py_hash_t hash;               /* hash value for read-only views */
+    int flags;                    /* state flags */
+    Py_ssize_t exports;           /* number of buffer re-exports */
+    Py_buffer view;               /* private copy of the exporter's view */
+    char format[_Py_MEMORYVIEW_MAX_FORMAT]; /* used for casting */
+    Py_ssize_t ob_array[1];       /* shape, strides, suboffsets */
 } PyMemoryViewObject;
 #endif
 
diff --git a/Include/object.h b/Include/object.h
index 71d9dc8f76..9b3055df49 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -186,15 +186,16 @@ typedef struct bufferinfo {
     Py_ssize_t *shape;
     Py_ssize_t *strides;
     Py_ssize_t *suboffsets;
-    Py_ssize_t smalltable[2];  /* static store for shape and strides of
-                                  mono-dimensional buffers. */
     void *internal;
 } Py_buffer;
 
 typedef int (*getbufferproc)(PyObject *, Py_buffer *, int);
 typedef void (*releasebufferproc)(PyObject *, Py_buffer *);
 
-    /* Flags for getting buffers */
+/* Maximum number of dimensions */
+#define PyBUF_MAX_NDIM 64
+
+/* Flags for getting buffers */
 #define PyBUF_SIMPLE 0
 #define PyBUF_WRITABLE 0x0001
 /*  we used to include an E, backwards compatible alias  */
diff --git a/Lib/ctypes/test/test_pep3118.py b/Lib/ctypes/test/test_pep3118.py
index fa6461f546..ad13b016e7 100644
--- a/Lib/ctypes/test/test_pep3118.py
+++ b/Lib/ctypes/test/test_pep3118.py
@@ -25,14 +25,17 @@ class Test(unittest.TestCase):
             v = memoryview(ob)
             try:
                 self.assertEqual(normalize(v.format), normalize(fmt))
-                if shape is not None:
+                if shape:
                     self.assertEqual(len(v), shape[0])
                 else:
                     self.assertEqual(len(v) * sizeof(itemtp), sizeof(ob))
                 self.assertEqual(v.itemsize, sizeof(itemtp))
                 self.assertEqual(v.shape, shape)
-                # ctypes object always have a non-strided memory block
-                self.assertEqual(v.strides, None)
+                # XXX Issue #12851: PyCData_NewGetBuffer() must provide strides
+                #     if requested. memoryview currently reconstructs missing
+                #     stride information, so this assert will fail.
+                # self.assertEqual(v.strides, ())
+
                 # they are always read/write
                 self.assertFalse(v.readonly)
 
@@ -52,14 +55,15 @@ class Test(unittest.TestCase):
             v = memoryview(ob)
             try:
                 self.assertEqual(v.format, fmt)
-                if shape is not None:
+                if shape:
                     self.assertEqual(len(v), shape[0])
                 else:
                     self.assertEqual(len(v) * sizeof(itemtp), sizeof(ob))
                 self.assertEqual(v.itemsize, sizeof(itemtp))
                 self.assertEqual(v.shape, shape)
-                # ctypes object always have a non-strided memory block
-                self.assertEqual(v.strides, None)
+                # XXX Issue #12851
+                # self.assertEqual(v.strides, ())
+
                 # they are always read/write
                 self.assertFalse(v.readonly)
 
@@ -110,34 +114,34 @@ native_types = [
 
     ## simple types
 
-    (c_char,                    "<c",                   None,           c_char),
-    (c_byte,                    "<b",                   None,           c_byte),
-    (c_ubyte,                   "<B",                   None,           c_ubyte),
-    (c_short,                   "<h",                   None,           c_short),
-    (c_ushort,                  "<H",                   None,           c_ushort),
+    (c_char,                    "<c",                   (),           c_char),
+    (c_byte,                    "<b",                   (),           c_byte),
+    (c_ubyte,                   "<B",                   (),           c_ubyte),
+    (c_short,                   "<h",                   (),           c_short),
+    (c_ushort,                  "<H",                   (),           c_ushort),
 
     # c_int and c_uint may be aliases to c_long
-    #(c_int,                     "<i",                   None,           c_int),
-    #(c_uint,                    "<I",                   None,           c_uint),
+    #(c_int,                     "<i",                   (),           c_int),
+    #(c_uint,                    "<I",                   (),           c_uint),
 
-    (c_long,                    "<l",                   None,           c_long),
-    (c_ulong,                   "<L",                   None,           c_ulong),
+    (c_long,                    "<l",                   (),           c_long),
+    (c_ulong,                   "<L",                   (),           c_ulong),
 
     # c_longlong and c_ulonglong are aliases on 64-bit platforms
     #(c_longlong,                "<q",                   None,           c_longlong),
     #(c_ulonglong,               "<Q",                   None,           c_ulonglong),
 
-    (c_float,                   "<f",                   None,           c_float),
-    (c_double,                  "<d",                   None,           c_double),
+    (c_float,                   "<f",                   (),           c_float),
+    (c_double,                  "<d",                   (),           c_double),
     # c_longdouble may be an alias to c_double
 
-    (c_bool,                    "<?",                   None,           c_bool),
-    (py_object,                 "<O",                   None,           py_object),
+    (c_bool,                    "<?",                   (),           c_bool),
+    (py_object,                 "<O",                   (),           py_object),
 
     ## pointers
 
-    (POINTER(c_byte),           "&<b",                  None,           POINTER(c_byte)),
-    (POINTER(POINTER(c_long)),  "&&<l",                 None,           POINTER(POINTER(c_long))),
+    (POINTER(c_byte),           "&<b",                  (),           POINTER(c_byte)),
+    (POINTER(POINTER(c_long)),  "&&<l",                 (),           POINTER(POINTER(c_long))),
 
     ## arrays and pointers
 
@@ -145,32 +149,32 @@ native_types = [
     (c_float * 4 * 3 * 2,       "(2,3,4)<f",            (2,3,4),        c_float),
     (POINTER(c_short) * 2,      "(2)&<h",               (2,),           POINTER(c_short)),
     (POINTER(c_short) * 2 * 3,  "(3,2)&<h",             (3,2,),         POINTER(c_short)),
-    (POINTER(c_short * 2),      "&(2)<h",               None,           POINTER(c_short)),
+    (POINTER(c_short * 2),      "&(2)<h",               (),           POINTER(c_short)),
 
     ## structures and unions
 
-    (Point,                     "T{<l:x:<l:y:}",        None,           Point),
+    (Point,                     "T{<l:x:<l:y:}",        (),           Point),
     # packed structures do not implement the pep
-    (PackedPoint,               "B",                    None,           PackedPoint),
-    (Point2,                    "T{<l:x:<l:y:}",        None,           Point2),
-    (EmptyStruct,               "T{}",                  None,           EmptyStruct),
+    (PackedPoint,               "B",                    (),           PackedPoint),
+    (Point2,                    "T{<l:x:<l:y:}",        (),           Point2),
+    (EmptyStruct,               "T{}",                  (),           EmptyStruct),
     # the pep does't support unions
-    (aUnion,                    "B",                    None,           aUnion),
+    (aUnion,                    "B",                    (),           aUnion),
 
     ## pointer to incomplete structure
-    (Incomplete,                "B",                    None,           Incomplete),
-    (POINTER(Incomplete),       "&B",                   None,           POINTER(Incomplete)),
+    (Incomplete,                "B",                    (),           Incomplete),
+    (POINTER(Incomplete),       "&B",                   (),           POINTER(Incomplete)),
 
     # 'Complete' is a structure that starts incomplete, but is completed after the
     # pointer type to it has been created.
-    (Complete,                  "T{<l:a:}",             None,           Complete),
+    (Complete,                  "T{<l:a:}",             (),           Complete),
     # Unfortunately the pointer format string is not fixed...
-    (POINTER(Complete),         "&B",                   None,           POINTER(Complete)),
+    (POINTER(Complete),         "&B",                   (),           POINTER(Complete)),
 
     ## other
 
     # function signatures are not implemented
-    (CFUNCTYPE(None),           "X{}",                  None,           CFUNCTYPE(None)),
+    (CFUNCTYPE(None),           "X{}",                  (),           CFUNCTYPE(None)),
 
     ]
 
@@ -186,10 +190,10 @@ class LEPoint(LittleEndianStructure):
 # and little endian machines.
 #
 endian_types = [
-    (BEPoint,                   "T{>l:x:>l:y:}",        None,           BEPoint),
-    (LEPoint,                   "T{<l:x:<l:y:}",        None,           LEPoint),
-    (POINTER(BEPoint),          "&T{>l:x:>l:y:}",       None,           POINTER(BEPoint)),
-    (POINTER(LEPoint),          "&T{<l:x:<l:y:}",       None,           POINTER(LEPoint)),
+    (BEPoint,                   "T{>l:x:>l:y:}",        (),           BEPoint),
+    (LEPoint,                   "T{<l:x:<l:y:}",        (),           LEPoint),
+    (POINTER(BEPoint),          "&T{>l:x:>l:y:}",       (),           POINTER(BEPoint)),
+    (POINTER(LEPoint),          "&T{<l:x:<l:y:}",       (),           POINTER(LEPoint)),
     ]
 
 if __name__ == "__main__":
diff --git a/Lib/test/test_buffer.py b/Lib/test/test_buffer.py
new file mode 100644
index 0000000000..25324efba6
--- /dev/null
+++ b/Lib/test/test_buffer.py
@@ -0,0 +1,3437 @@
+#
+# The ndarray object from _testbuffer.c is a complete implementation of
+# a PEP-3118 buffer provider. It is independent from NumPy's ndarray
+# and the tests don't require NumPy.
+#
+# If NumPy is present, some tests check both ndarray implementations
+# against each other.
+#
+# Most ndarray tests also check that memoryview(ndarray) behaves in
+# the same way as the original. Thus, a substantial part of the
+# memoryview tests is now in this module.
+#
+
+import unittest
+from test import support
+from itertools import permutations, product
+from random import randrange, sample, choice
+from sysconfig import get_config_var
+from platform import architecture
+import warnings
+import sys, array, io
+from decimal import Decimal
+from fractions import Fraction
+
+try:
+    from _testbuffer import *
+except ImportError:
+    ndarray = None
+
+try:
+    import struct
+except ImportError:
+    struct = None
+
+try:
+    with warnings.catch_warnings():
+        from numpy import ndarray as numpy_array
+except ImportError:
+    numpy_array = None
+
+
+SHORT_TEST = True
+
+
+# ======================================================================
+#                    Random lists by format specifier
+# ======================================================================
+
+# Native format chars and their ranges.
+NATIVE = {
+    '?':0, 'c':0, 'b':0, 'B':0,
+    'h':0, 'H':0, 'i':0, 'I':0,
+    'l':0, 'L':0, 'n':0, 'N':0,
+    'f':0, 'd':0, 'P':0
+}
+
+if struct:
+    try:
+        # Add "qQ" if present in native mode.
+        struct.pack('Q', 2**64-1)
+        NATIVE['q'] = 0
+        NATIVE['Q'] = 0
+    except struct.error:
+        pass
+
+# Standard format chars and their ranges.
+STANDARD = {
+    '?':(0, 2),            'c':(0, 1<<8),
+    'b':(-(1<<7), 1<<7),   'B':(0, 1<<8),
+    'h':(-(1<<15), 1<<15), 'H':(0, 1<<16),
+    'i':(-(1<<31), 1<<31), 'I':(0, 1<<32),
+    'l':(-(1<<31), 1<<31), 'L':(0, 1<<32),
+    'q':(-(1<<63), 1<<63), 'Q':(0, 1<<64),
+    'f':(-(1<<63), 1<<63), 'd':(-(1<<1023), 1<<1023)
+}
+
+def native_type_range(fmt):
+    """Return range of a native type."""
+    if fmt == 'c':
+        lh = (0, 256)
+    elif fmt == '?':
+        lh = (0, 2)
+    elif fmt == 'f':
+        lh = (-(1<<63), 1<<63)
+    elif fmt == 'd':
+        lh = (-(1<<1023), 1<<1023)
+    else:
+        for exp in (128, 127, 64, 63, 32, 31, 16, 15, 8, 7):
+            try:
+                struct.pack(fmt, (1<<exp)-1)
+                break
+            except struct.error:
+                pass
+        lh = (-(1<<exp), 1<<exp) if exp & 1 else (0, 1<<exp)
+    return lh
+
+fmtdict = {
+    '':NATIVE,
+    '@':NATIVE,
+    '<':STANDARD,
+    '>':STANDARD,
+    '=':STANDARD,
+    '!':STANDARD
+}
+
+if struct:
+    for fmt in fmtdict['@']:
+        fmtdict['@'][fmt] = native_type_range(fmt)
+
+MEMORYVIEW = NATIVE.copy()
+ARRAY = NATIVE.copy()
+for k in NATIVE:
+    if not k in "bBhHiIlLfd":
+        del ARRAY[k]
+
+BYTEFMT = NATIVE.copy()
+for k in NATIVE:
+    if not k in "Bbc":
+        del BYTEFMT[k]
+
+fmtdict['m']  = MEMORYVIEW
+fmtdict['@m'] = MEMORYVIEW
+fmtdict['a']  = ARRAY
+fmtdict['b']  = BYTEFMT
+fmtdict['@b']  = BYTEFMT
+
+# Capabilities of the test objects:
+MODE = 0
+MULT = 1
+cap = {         # format chars                  # multiplier
+  'ndarray':    (['', '@', '<', '>', '=', '!'], ['', '1', '2', '3']),
+  'array':      (['a'],                         ['']),
+  'numpy':      ([''],                          ['']),
+  'memoryview': (['@m', 'm'],                   ['']),
+  'bytefmt':    (['@b', 'b'],                   ['']),
+}
+
+def randrange_fmt(mode, char, obj):
+    """Return random item for a type specified by a mode and a single
+       format character."""
+    x = randrange(*fmtdict[mode][char])
+    if char == 'c':
+        x = bytes(chr(x), 'latin1')
+    if char == '?':
+        x = bool(x)
+    if char == 'f' or char == 'd':
+        x = struct.pack(char, x)
+        x = struct.unpack(char, x)[0]
+    if obj == 'numpy' and x == b'\x00':
+        # http://projects.scipy.org/numpy/ticket/1925
+        x = b'\x01'
+    return x
+
+def gen_item(fmt, obj):
+    """Return single random item."""
+    mode, chars = fmt.split('#')
+    x = []
+    for c in chars:
+        x.append(randrange_fmt(mode, c, obj))
+    return x[0] if len(x) == 1 else tuple(x)
+
+def gen_items(n, fmt, obj):
+    """Return a list of random items (or a scalar)."""
+    if n == 0:
+        return gen_item(fmt, obj)
+    lst = [0] * n
+    for i in range(n):
+        lst[i] = gen_item(fmt, obj)
+    return lst
+
+def struct_items(n, obj):
+    mode = choice(cap[obj][MODE])
+    xfmt = mode + '#'
+    fmt = mode.strip('amb')
+    nmemb = randrange(2, 10) # number of struct members
+    for _ in range(nmemb):
+        char = choice(tuple(fmtdict[mode]))
+        multiplier = choice(cap[obj][MULT])
+        xfmt += (char * int(multiplier if multiplier else 1))
+        fmt += (multiplier + char)
+    items = gen_items(n, xfmt, obj)
+    item = gen_item(xfmt, obj)
+    return fmt, items, item
+
+def randitems(n, obj='ndarray', mode=None, char=None):
+    """Return random format, items, item."""
+    if mode is None:
+        mode = choice(cap[obj][MODE])
+    if char is None:
+        char = choice(tuple(fmtdict[mode]))
+    multiplier = choice(cap[obj][MULT])
+    fmt = mode + '#' + char * int(multiplier if multiplier else 1)
+    items = gen_items(n, fmt, obj)
+    item = gen_item(fmt, obj)
+    fmt = mode.strip('amb') + multiplier + char
+    return fmt, items, item
+
+def iter_mode(n, obj='ndarray'):
+    """Iterate through supported mode/char combinations."""
+    for mode in cap[obj][MODE]:
+        for char in fmtdict[mode]:
+            yield randitems(n, obj, mode, char)
+
+def iter_format(nitems, testobj='ndarray'):
+    """Yield (format, items, item) for all possible modes and format
+       characters plus one random compound format string."""
+    for t in iter_mode(nitems, testobj):
+        yield t
+    if testobj != 'ndarray':
+        raise StopIteration
+    yield struct_items(nitems, testobj)
+
+
+def is_byte_format(fmt):
+    return 'c' in fmt or 'b' in fmt or 'B' in fmt
+
+def is_memoryview_format(fmt):
+    """format suitable for memoryview"""
+    x = len(fmt)
+    return ((x == 1 or (x == 2 and fmt[0] == '@')) and
+            fmt[x-1] in MEMORYVIEW)
+
+NON_BYTE_FORMAT = [c for c in fmtdict['@'] if not is_byte_format(c)]
+
+
+# ======================================================================
+#       Multi-dimensional tolist(), slicing and slice assignments
+# ======================================================================
+
+def atomp(lst):
+    """Tuple items (representing structs) are regarded as atoms."""
+    return not isinstance(lst, list)
+
+def listp(lst):
+    return isinstance(lst, list)
+
+def prod(lst):
+    """Product of list elements."""
+    if len(lst) == 0:
+        return 0
+    x = lst[0]
+    for v in lst[1:]:
+        x *= v
+    return x
+
+def strides_from_shape(ndim, shape, itemsize, layout):
+    """Calculate strides of a contiguous array. Layout is 'C' or
+       'F' (Fortran)."""
+    if ndim == 0:
+        return ()
+    if layout == 'C':
+        strides = list(shape[1:]) + [itemsize]
+        for i in range(ndim-2, -1, -1):
+            strides[i] *= strides[i+1]
+    else:
+        strides = [itemsize] + list(shape[:-1])
+        for i in range(1, ndim):
+            strides[i] *= strides[i-1]
+    return strides
+
+def _ca(items, s):
+    """Convert flat item list to the nested list representation of a
+       multidimensional C array with shape 's'."""
+    if atomp(items):
+        return items
+    if len(s) == 0:
+        return items[0]
+    lst = [0] * s[0]
+    stride = len(items) // s[0] if s[0] else 0
+    for i in range(s[0]):
+        start = i*stride
+        lst[i] = _ca(items[start:start+stride], s[1:])
+    return lst
+
+def _fa(items, s):
+    """Convert flat item list to the nested list representation of a
+       multidimensional Fortran array with shape 's'."""
+    if atomp(items):
+        return items
+    if len(s) == 0:
+        return items[0]
+    lst = [0] * s[0]
+    stride = s[0]
+    for i in range(s[0]):
+        lst[i] = _fa(items[i::stride], s[1:])
+    return lst
+
+def carray(items, shape):
+    if listp(items) and not 0 in shape and prod(shape) != len(items):
+        raise ValueError("prod(shape) != len(items)")
+    return _ca(items, shape)
+
+def farray(items, shape):
+    if listp(items) and not 0 in shape and prod(shape) != len(items):
+        raise ValueError("prod(shape) != len(items)")
+    return _fa(items, shape)
+
+def indices(shape):
+    """Generate all possible tuples of indices."""
+    iterables = [range(v) for v in shape]
+    return product(*iterables)
+
+def getindex(ndim, ind, strides):
+    """Convert multi-dimensional index to the position in the flat list."""
+    ret = 0
+    for i in range(ndim):
+        ret += strides[i] * ind[i]
+    return ret
+
+def transpose(src, shape):
+    """Transpose flat item list that is regarded as a multi-dimensional
+       matrix defined by shape: dest...[k][j][i] = src[i][j][k]...  """
+    if not shape:
+        return src
+    ndim = len(shape)
+    sstrides = strides_from_shape(ndim, shape, 1, 'C')
+    dstrides = strides_from_shape(ndim, shape[::-1], 1, 'C')
+    dest = [0] * len(src)
+    for ind in indices(shape):
+        fr = getindex(ndim, ind, sstrides)
+        to = getindex(ndim, ind[::-1], dstrides)
+        dest[to] = src[fr]
+    return dest
+
+def _flatten(lst):
+    """flatten list"""
+    if lst == []:
+        return lst
+    if atomp(lst):
+        return [lst]
+    return _flatten(lst[0]) + _flatten(lst[1:])
+
+def flatten(lst):
+    """flatten list or return scalar"""
+    if atomp(lst): # scalar
+        return lst
+    return _flatten(lst)
+
+def slice_shape(lst, slices):
+    """Get the shape of lst after slicing: slices is a list of slice
+       objects."""
+    if atomp(lst):
+        return []
+    return [len(lst[slices[0]])] + slice_shape(lst[0], slices[1:])
+
+def multislice(lst, slices):
+    """Multi-dimensional slicing: slices is a list of slice objects."""
+    if atomp(lst):
+        return lst
+    return [multislice(sublst, slices[1:]) for sublst in lst[slices[0]]]
+
+def m_assign(llst, rlst, lslices, rslices):
+    """Multi-dimensional slice assignment: llst and rlst are the operands,
+       lslices and rslices are lists of slice objects. llst and rlst must
+       have the same structure.
+
+       For a two-dimensional example, this is not implemented in Python:
+
+         llst[0:3:2, 0:3:2] = rlst[1:3:1, 1:3:1]
+
+       Instead we write:
+
+         lslices = [slice(0,3,2), slice(0,3,2)]
+         rslices = [slice(1,3,1), slice(1,3,1)]
+         multislice_assign(llst, rlst, lslices, rslices)
+    """
+    if atomp(rlst):
+        return rlst
+    rlst = [m_assign(l, r, lslices[1:], rslices[1:])
+            for l, r in zip(llst[lslices[0]], rlst[rslices[0]])]
+    llst[lslices[0]] = rlst
+    return llst
+
+def cmp_structure(llst, rlst, lslices, rslices):
+    """Compare the structure of llst[lslices] and rlst[rslices]."""
+    lshape = slice_shape(llst, lslices)
+    rshape = slice_shape(rlst, rslices)
+    if (len(lshape) != len(rshape)):
+        return -1
+    for i in range(len(lshape)):
+        if lshape[i] != rshape[i]:
+            return -1
+        if lshape[i] == 0:
+            return 0
+    return 0
+
+def multislice_assign(llst, rlst, lslices, rslices):
+    """Return llst after assigning: llst[lslices] = rlst[rslices]"""
+    if cmp_structure(llst, rlst, lslices, rslices) < 0:
+        raise ValueError("lvalue and rvalue have different structures")
+    return m_assign(llst, rlst, lslices, rslices)
+
+
+# ======================================================================
+#                          Random structures
+# ======================================================================
+
+#
+# PEP-3118 is very permissive with respect to the contents of a
+# Py_buffer. In particular:
+#
+#   - shape can be zero
+#   - strides can be any integer, including zero
+#   - offset can point to any location in the underlying
+#     memory block, provided that it is a multiple of
+#     itemsize.
+#
+# The functions in this section test and verify random structures
+# in full generality. A structure is valid iff it fits in the
+# underlying memory block.
+#
+# The structure 't' (short for 'tuple') is fully defined by:
+#
+#   t = (memlen, itemsize, ndim, shape, strides, offset)
+#
+
+def verify_structure(memlen, itemsize, ndim, shape, strides, offset):
+    """Verify that the parameters represent a valid array within
+       the bounds of the allocated memory:
+           char *mem: start of the physical memory block
+           memlen: length of the physical memory block
+           offset: (char *)buf - mem
+    """
+    if offset % itemsize:
+        return False
+    if offset < 0 or offset+itemsize > memlen:
+        return False
+    if any(v % itemsize for v in strides):
+        return False
+
+    if ndim <= 0:
+        return ndim == 0 and not shape and not strides
+    if 0 in shape:
+        return True
+
+    imin = sum(strides[j]*(shape[j]-1) for j in range(ndim)
+               if strides[j] <= 0)
+    imax = sum(strides[j]*(shape[j]-1) for j in range(ndim)
+               if strides[j] > 0)
+
+    return 0 <= offset+imin and offset+imax+itemsize <= memlen
+
+def get_item(lst, indices):
+    for i in indices:
+        lst = lst[i]
+    return lst
+
+def memory_index(indices, t):
+    """Location of an item in the underlying memory."""
+    memlen, itemsize, ndim, shape, strides, offset = t
+    p = offset
+    for i in range(ndim):
+        p += strides[i]*indices[i]
+    return p
+
+def is_overlapping(t):
+    """The structure 't' is overlapping if at least one memory location
+       is visited twice while iterating through all possible tuples of
+       indices."""
+    memlen, itemsize, ndim, shape, strides, offset = t
+    visited = 1<<memlen
+    for ind in indices(shape):
+        i = memory_index(ind, t)
+        bit = 1<<i
+        if visited & bit:
+            return True
+        visited |= bit
+    return False
+
+def rand_structure(itemsize, valid, maxdim=5, maxshape=16, shape=()):
+    """Return random structure:
+           (memlen, itemsize, ndim, shape, strides, offset)
+       If 'valid' is true, the returned structure is valid, otherwise invalid.
+       If 'shape' is given, use that instead of creating a random shape.
+    """
+    if not shape:
+        ndim = randrange(maxdim+1)
+        if (ndim == 0):
+            if valid:
+                return itemsize, itemsize, ndim, (), (), 0
+            else:
+                nitems = randrange(1, 16+1)
+                memlen = nitems * itemsize
+                offset = -itemsize if randrange(2) == 0 else memlen
+                return memlen, itemsize, ndim, (), (), offset
+
+        minshape = 2
+        n = randrange(100)
+        if n >= 95 and valid:
+            minshape = 0
+        elif n >= 90:
+            minshape = 1
+        shape = [0] * ndim
+
+        for i in range(ndim):
+            shape[i] = randrange(minshape, maxshape+1)
+    else:
+        ndim = len(shape)
+
+    maxstride = 5
+    n = randrange(100)
+    zero_stride = True if n >= 95 and n & 1 else False
+
+    strides = [0] * ndim
+    strides[ndim-1] = itemsize * randrange(-maxstride, maxstride+1)
+    if not zero_stride and strides[ndim-1] == 0:
+        strides[ndim-1] = itemsize
+
+    for i in range(ndim-2, -1, -1):
+        maxstride *= shape[i+1] if shape[i+1] else 1
+        if zero_stride:
+            strides[i] = itemsize * randrange(-maxstride, maxstride+1)
+        else:
+            strides[i] = ((1,-1)[randrange(2)] *
+                          itemsize * randrange(1, maxstride+1))
+
+    imin = imax = 0
+    if not 0 in shape:
+        imin = sum(strides[j]*(shape[j]-1) for j in range(ndim)
+                   if strides[j] <= 0)
+        imax = sum(strides[j]*(shape[j]-1) for j in range(ndim)
+                   if strides[j] > 0)
+
+    nitems = imax - imin
+    if valid:
+        offset = -imin * itemsize
+        memlen = offset + (imax+1) * itemsize
+    else:
+        memlen = (-imin + imax) * itemsize
+        offset = -imin-itemsize if randrange(2) == 0 else memlen
+    return memlen, itemsize, ndim, shape, strides, offset
+
+def randslice_from_slicelen(slicelen, listlen):
+    """Create a random slice of len slicelen that fits into listlen."""
+    maxstart = listlen - slicelen
+    start = randrange(maxstart+1)
+    maxstep = (listlen - start) // slicelen if slicelen else 1
+    step = randrange(1, maxstep+1)
+    stop = start + slicelen * step
+    s = slice(start, stop, step)
+    _, _, _, control = slice_indices(s, listlen)
+    if control != slicelen:
+        raise RuntimeError
+    return s
+
+def randslice_from_shape(ndim, shape):
+    """Create two sets of slices for an array x with shape 'shape'
+       such that shapeof(x[lslices]) == shapeof(x[rslices])."""
+    lslices = [0] * ndim
+    rslices = [0] * ndim
+    for n in range(ndim):
+        l = shape[n]
+        slicelen = randrange(1, l+1) if l > 0 else 0
+        lslices[n] = randslice_from_slicelen(slicelen, l)
+        rslices[n] = randslice_from_slicelen(slicelen, l)
+    return tuple(lslices), tuple(rslices)
+
+def rand_aligned_slices(maxdim=5, maxshape=16):
+    """Create (lshape, rshape, tuple(lslices), tuple(rslices)) such that
+       shapeof(x[lslices]) == shapeof(y[rslices]), where x is an array
+       with shape 'lshape' and y is an array with shape 'rshape'."""
+    ndim = randrange(1, maxdim+1)
+    minshape = 2
+    n = randrange(100)
+    if n >= 95:
+        minshape = 0
+    elif n >= 90:
+        minshape = 1
+    all_random = True if randrange(100) >= 80 else False
+    lshape = [0]*ndim; rshape = [0]*ndim
+    lslices = [0]*ndim; rslices = [0]*ndim
+
+    for n in range(ndim):
+        small = randrange(minshape, maxshape+1)
+        big = randrange(minshape, maxshape+1)
+        if big < small:
+            big, small = small, big
+
+        # Create a slice that fits the smaller value.
+        if all_random:
+            start = randrange(-small, small+1)
+            stop = randrange(-small, small+1)
+            step = (1,-1)[randrange(2)] * randrange(1, small+2)
+            s_small = slice(start, stop, step)
+            _, _, _, slicelen = slice_indices(s_small, small)
+        else:
+            slicelen = randrange(1, small+1) if small > 0 else 0
+            s_small = randslice_from_slicelen(slicelen, small)
+
+        # Create a slice of the same length for the bigger value.
+        s_big = randslice_from_slicelen(slicelen, big)
+        if randrange(2) == 0:
+            rshape[n], lshape[n] = big, small
+            rslices[n], lslices[n] = s_big, s_small
+        else:
+            rshape[n], lshape[n] = small, big
+            rslices[n], lslices[n] = s_small, s_big
+
+    return lshape, rshape, tuple(lslices), tuple(rslices)
+
+def randitems_from_structure(fmt, t):
+    """Return a list of random items for structure 't' with format
+       'fmtchar'."""
+    memlen, itemsize, _, _, _, _ = t
+    return gen_items(memlen//itemsize, '#'+fmt, 'numpy')
+
+def ndarray_from_structure(items, fmt, t, flags=0):
+    """Return ndarray from the tuple returned by rand_structure()"""
+    memlen, itemsize, ndim, shape, strides, offset = t
+    return ndarray(items, shape=shape, strides=strides, format=fmt,
+                   offset=offset, flags=ND_WRITABLE|flags)
+
+def numpy_array_from_structure(items, fmt, t):
+    """Return numpy_array from the tuple returned by rand_structure()"""
+    memlen, itemsize, ndim, shape, strides, offset = t
+    buf = bytearray(memlen)
+    for j, v in enumerate(items):
+        struct.pack_into(fmt, buf, j*itemsize, v)
+    return numpy_array(buffer=buf, shape=shape, strides=strides,
+                       dtype=fmt, offset=offset)
+
+
+# ======================================================================
+#                          memoryview casts
+# ======================================================================
+
+def cast_items(exporter, fmt, itemsize, shape=None):
+    """Interpret the raw memory of 'exporter' as a list of items with
+       size 'itemsize'. If shape=None, the new structure is assumed to
+       be 1-D with n * itemsize = bytelen. If shape is given, the usual
+       constraint for contiguous arrays prod(shape) * itemsize = bytelen
+       applies. On success, return (items, shape). If the constraints
+       cannot be met, return (None, None). If a chunk of bytes is interpreted
+       as NaN as a result of float conversion, return ('nan', None)."""
+    bytelen = exporter.nbytes
+    if shape:
+        if prod(shape) * itemsize != bytelen:
+            return None, shape
+    elif shape == []:
+        if exporter.ndim == 0 or itemsize != bytelen:
+            return None, shape
+    else:
+        n, r = divmod(bytelen, itemsize)
+        shape = [n]
+        if r != 0:
+            return None, shape
+
+    mem = exporter.tobytes()
+    byteitems = [mem[i:i+itemsize] for i in range(0, len(mem), itemsize)]
+
+    items = []
+    for v in byteitems:
+        item = struct.unpack(fmt, v)[0]
+        if item != item:
+            return 'nan', shape
+        items.append(item)
+
+    return (items, shape) if shape != [] else (items[0], shape)
+
+def gencastshapes():
+    """Generate shapes to test casting."""
+    for n in range(32):
+        yield [n]
+    ndim = randrange(4, 6)
+    minshape = 1 if randrange(100) > 80 else 2
+    yield [randrange(minshape, 5) for _ in range(ndim)]
+    ndim = randrange(2, 4)
+    minshape = 1 if randrange(100) > 80 else 2
+    yield [randrange(minshape, 5) for _ in range(ndim)]
+
+
+# ======================================================================
+#                              Actual tests
+# ======================================================================
+
+def genslices(n):
+    """Generate all possible slices for a single dimension."""
+    return product(range(-n, n+1), range(-n, n+1), range(-n, n+1))
+
+def genslices_ndim(ndim, shape):
+    """Generate all possible slice tuples for 'shape'."""
+    iterables = [genslices(shape[n]) for n in range(ndim)]
+    return product(*iterables)
+
+def rslice(n, allow_empty=False):
+    """Generate random slice for a single dimension of length n.
+       If zero=True, the slices may be empty, otherwise they will
+       be non-empty."""
+    minlen = 0 if allow_empty or n == 0 else 1
+    slicelen = randrange(minlen, n+1)
+    return randslice_from_slicelen(slicelen, n)
+
+def rslices(n, allow_empty=False):
+    """Generate random slices for a single dimension."""
+    for _ in range(5):
+        yield rslice(n, allow_empty)
+
+def rslices_ndim(ndim, shape, iterations=5):
+    """Generate random slice tuples for 'shape'."""
+    # non-empty slices
+    for _ in range(iterations):
+        yield tuple(rslice(shape[n]) for n in range(ndim))
+    # possibly empty slices
+    for _ in range(iterations):
+        yield tuple(rslice(shape[n], allow_empty=True) for n in range(ndim))
+    # invalid slices
+    yield tuple(slice(0,1,0) for _ in range(ndim))
+
+def rpermutation(iterable, r=None):
+    pool = tuple(iterable)
+    r = len(pool) if r is None else r
+    yield tuple(sample(pool, r))
+
+def ndarray_print(nd):
+    """Print ndarray for debugging."""
+    try:
+        x = nd.tolist()
+    except (TypeError, NotImplementedError):
+        x = nd.tobytes()
+    if isinstance(nd, ndarray):
+        offset = nd.offset
+        flags = nd.flags
+    else:
+        offset = 'unknown'
+        flags = 'unknown'
+    print("ndarray(%s, shape=%s, strides=%s, suboffsets=%s, offset=%s, "
+          "format='%s', itemsize=%s, flags=%s)" %
+          (x, nd.shape, nd.strides, nd.suboffsets, offset,
+           nd.format, nd.itemsize, flags))
+    sys.stdout.flush()
+
+
+ITERATIONS = 100
+MAXDIM = 5
+MAXSHAPE = 10
+
+if SHORT_TEST:
+    ITERATIONS = 10
+    MAXDIM = 3
+    MAXSHAPE = 4
+    genslices = rslices
+    genslices_ndim = rslices_ndim
+    permutations = rpermutation
+
+
+@unittest.skipUnless(struct, 'struct module required for this test.')
+@unittest.skipUnless(ndarray, 'ndarray object required for this test')
+class TestBufferProtocol(unittest.TestCase):
+
+    def setUp(self):
+        self.sizeof_void_p = get_config_var('SIZEOF_VOID_P')
+        if not self.sizeof_void_p:
+            self.sizeof_void_p = 8 if architecture()[0] == '64bit' else 4
+
+    def verify(self, result, obj=-1,
+                     itemsize={1}, fmt=-1, readonly={1},
+                     ndim={1}, shape=-1, strides=-1,
+                     lst=-1, sliced=False, cast=False):
+        # Verify buffer contents against expected values. Default values
+        # are deliberately initialized to invalid types.
+        if shape:
+            expected_len = prod(shape)*itemsize
+        else:
+            if not fmt: # array has been implicitly cast to unsigned bytes
+                expected_len = len(lst)
+            else: # ndim = 0
+                expected_len = itemsize
+
+        # Reconstruct suboffsets from strides. Support for slicing
+        # could be added, but is currently only needed for test_getbuf().
+        suboffsets = ()
+        if result.suboffsets:
+            self.assertGreater(ndim, 0)
+
+            suboffset0 = 0
+            for n in range(1, ndim):
+                if shape[n] == 0:
+                    break
+                if strides[n] <= 0:
+                    suboffset0 += -strides[n] * (shape[n]-1)
+
+            suboffsets = [suboffset0] + [-1 for v in range(ndim-1)]
+
+            # Not correct if slicing has occurred in the first dimension.
+            stride0 = self.sizeof_void_p
+            if strides[0] < 0:
+                stride0 = -stride0
+            strides = [stride0] + list(strides[1:])
+
+        self.assertIs(result.obj, obj)
+        self.assertEqual(result.nbytes, expected_len)
+        self.assertEqual(result.itemsize, itemsize)
+        self.assertEqual(result.format, fmt)
+        self.assertEqual(result.readonly, readonly)
+        self.assertEqual(result.ndim, ndim)
+        self.assertEqual(result.shape, tuple(shape))
+        if not (sliced and suboffsets):
+            self.assertEqual(result.strides, tuple(strides))
+        self.assertEqual(result.suboffsets, tuple(suboffsets))
+
+        if isinstance(result, ndarray) or is_memoryview_format(fmt):
+            rep = result.tolist() if fmt else result.tobytes()
+            self.assertEqual(rep, lst)
+
+        if not fmt: # array has been cast to unsigned bytes,
+            return  # the remaining tests won't work.
+
+        # PyBuffer_GetPointer() is the definition how to access an item.
+        # If PyBuffer_GetPointer(indices) is correct for all possible
+        # combinations of indices, the buffer is correct.
+        #
+        # Also test tobytes() against the flattened 'lst', with all items
+        # packed to bytes.
+        if not cast: # casts chop up 'lst' in different ways
+            b = bytearray()
+            buf_err = None
+            for ind in indices(shape):
+                try:
+                    item1 = get_pointer(result, ind)
+                    item2 = get_item(lst, ind)
+                    if isinstance(item2, tuple):
+                        x = struct.pack(fmt, *item2)
+                    else:
+                        x = struct.pack(fmt, item2)
+                    b.extend(x)
+                except BufferError:
+                    buf_err = True # re-exporter does not provide full buffer
+                    break
+                self.assertEqual(item1, item2)
+
+            if not buf_err:
+                # test tobytes()
+                self.assertEqual(result.tobytes(), b)
+
+            if not buf_err and is_memoryview_format(fmt):
+
+                # lst := expected multi-dimensional logical representation
+                # flatten(lst) := elements in C-order
+                ff = fmt if fmt else 'B'
+                flattened = flatten(lst)
+
+                # Rules for 'A': if the array is already contiguous, return
+                # the array unaltered. Otherwise, return a contiguous 'C'
+                # representation.
+                for order in ['C', 'F', 'A']:
+                    expected = result
+                    if order == 'F':
+                        if not is_contiguous(result, 'A') or \
+                           is_contiguous(result, 'C'):
+                            # For constructing the ndarray, convert the
+                            # flattened logical representation to Fortran order.
+                            trans = transpose(flattened, shape)
+                            expected = ndarray(trans, shape=shape, format=ff,
+                                               flags=ND_FORTRAN)
+                    else: # 'C', 'A'
+                        if not is_contiguous(result, 'A') or \
+                           is_contiguous(result, 'F') and order == 'C':
+                            # The flattened list is already in C-order.
+                            expected = ndarray(flattened, shape=shape, format=ff)
+                            contig = get_contiguous(result, PyBUF_READ, order)
+                    contig = get_contiguous(result, PyBUF_READ, order)
+                    self.assertEqual(contig.tobytes(), b)
+                    self.assertTrue(cmp_contig(contig, expected))
+
+        if is_memoryview_format(fmt):
+            try:
+                m = memoryview(result)
+            except BufferError: # re-exporter does not provide full information
+                return
+            ex = result.obj if isinstance(result, memoryview) else result
+            self.assertIs(m.obj, ex)
+            self.assertEqual(m.nbytes, expected_len)
+            self.assertEqual(m.itemsize, itemsize)
+            self.assertEqual(m.format, fmt)
+            self.assertEqual(m.readonly, readonly)
+            self.assertEqual(m.ndim, ndim)
+            self.assertEqual(m.shape, tuple(shape))
+            if not (sliced and suboffsets):
+                self.assertEqual(m.strides, tuple(strides))
+            self.assertEqual(m.suboffsets, tuple(suboffsets))
+
+            n = 1 if ndim == 0 else len(lst)
+            self.assertEqual(len(m), n)
+
+            rep = result.tolist() if fmt else result.tobytes()
+            self.assertEqual(rep, lst)
+            self.assertEqual(m, result)
+
+    def verify_getbuf(self, orig_ex, ex, req, sliced=False):
+        def simple_fmt(ex):
+            return ex.format == '' or ex.format == 'B'
+        def match(req, flag):
+            return ((req&flag) == flag)
+
+        if (# writable request to read-only exporter
+            (ex.readonly and match(req, PyBUF_WRITABLE)) or
+            # cannot match explicit contiguity request
+            (match(req, PyBUF_C_CONTIGUOUS) and not ex.c_contiguous) or
+            (match(req, PyBUF_F_CONTIGUOUS) and not ex.f_contiguous) or
+            (match(req, PyBUF_ANY_CONTIGUOUS) and not ex.contiguous) or
+            # buffer needs suboffsets
+            (not match(req, PyBUF_INDIRECT) and ex.suboffsets) or
+            # buffer without strides must be C-contiguous
+            (not match(req, PyBUF_STRIDES) and not ex.c_contiguous) or
+            # PyBUF_SIMPLE|PyBUF_FORMAT and PyBUF_WRITABLE|PyBUF_FORMAT
+            (not match(req, PyBUF_ND) and match(req, PyBUF_FORMAT))):
+
+            self.assertRaises(BufferError, ndarray, ex, getbuf=req)
+            return
+
+        if isinstance(ex, ndarray) or is_memoryview_format(ex.format):
+            lst = ex.tolist()
+        else:
+            nd = ndarray(ex, getbuf=PyBUF_FULL_RO)
+            lst = nd.tolist()
+
+        # The consumer may have requested default values or a NULL format.
+        ro = 0 if match(req, PyBUF_WRITABLE) else ex.readonly
+        fmt = ex.format
+        itemsize = ex.itemsize
+        ndim = ex.ndim
+        if not match(req, PyBUF_FORMAT):
+            # itemsize refers to the original itemsize before the cast.
+            # The equality product(shape) * itemsize = len still holds.
+            # The equality calcsize(format) = itemsize does _not_ hold.
+            fmt = ''
+            lst = orig_ex.tobytes() # Issue 12834
+        if not match(req, PyBUF_ND):
+            ndim = 1
+        shape = orig_ex.shape if match(req, PyBUF_ND) else ()
+        strides = orig_ex.strides if match(req, PyBUF_STRIDES) else ()
+
+        nd = ndarray(ex, getbuf=req)
+        self.verify(nd, obj=ex,
+                    itemsize=itemsize, fmt=fmt, readonly=ro,
+                    ndim=ndim, shape=shape, strides=strides,
+                    lst=lst, sliced=sliced)
+
+    def test_ndarray_getbuf(self):
+        requests = (
+            # distinct flags
+            PyBUF_INDIRECT, PyBUF_STRIDES, PyBUF_ND, PyBUF_SIMPLE,
+            PyBUF_C_CONTIGUOUS, PyBUF_F_CONTIGUOUS, PyBUF_ANY_CONTIGUOUS,
+            # compound requests
+            PyBUF_FULL, PyBUF_FULL_RO,
+            PyBUF_RECORDS, PyBUF_RECORDS_RO,
+            PyBUF_STRIDED, PyBUF_STRIDED_RO,
+            PyBUF_CONTIG, PyBUF_CONTIG_RO,
+        )
+        # items and format
+        items_fmt = (
+            ([True if x % 2 else False for x in range(12)], '?'),
+            ([1,2,3,4,5,6,7,8,9,10,11,12], 'b'),
+            ([1,2,3,4,5,6,7,8,9,10,11,12], 'B'),
+            ([(2**31-x) if x % 2 else (-2**31+x) for x in range(12)], 'l')
+        )
+        # shape, strides, offset
+        structure = (
+            ([], [], 0),
+            ([12], [], 0),
+            ([12], [-1], 11),
+            ([6], [2], 0),
+            ([6], [-2], 11),
+            ([3, 4], [], 0),
+            ([3, 4], [-4, -1], 11),
+            ([2, 2], [4, 1], 4),
+            ([2, 2], [-4, -1], 8)
+        )
+        # ndarray creation flags
+        ndflags = (
+            0, ND_WRITABLE, ND_FORTRAN, ND_FORTRAN|ND_WRITABLE,
+            ND_PIL, ND_PIL|ND_WRITABLE
+        )
+        # flags that can actually be used as flags
+        real_flags = (0, PyBUF_WRITABLE, PyBUF_FORMAT,
+                      PyBUF_WRITABLE|PyBUF_FORMAT)
+
+        for items, fmt in items_fmt:
+            itemsize = struct.calcsize(fmt)
+            for shape, strides, offset in structure:
+                strides = [v * itemsize for v in strides]
+                offset *= itemsize
+                for flags in ndflags:
+
+                    if strides and (flags&ND_FORTRAN):
+                        continue
+                    if not shape and (flags&ND_PIL):
+                        continue
+
+                    _items = items if shape else items[0]
+                    ex1 = ndarray(_items, format=fmt, flags=flags,
+                                  shape=shape, strides=strides, offset=offset)
+                    ex2 = ex1[::-2] if shape else None
+
+                    m1 = memoryview(ex1)
+                    if ex2:
+                        m2 = memoryview(ex2)
+                    if ex1.ndim == 0 or (ex1.ndim == 1 and shape and strides):
+                        self.assertEqual(m1, ex1)
+                    if ex2 and ex2.ndim == 1 and shape and strides:
+                        self.assertEqual(m2, ex2)
+
+                    for req in requests:
+                        for bits in real_flags:
+                            self.verify_getbuf(ex1, ex1, req|bits)
+                            self.verify_getbuf(ex1, m1, req|bits)
+                            if ex2:
+                                self.verify_getbuf(ex2, ex2, req|bits,
+                                                   sliced=True)
+                                self.verify_getbuf(ex2, m2, req|bits,
+                                                   sliced=True)
+
+        items = [1,2,3,4,5,6,7,8,9,10,11,12]
+
+        # ND_GETBUF_FAIL
+        ex = ndarray(items, shape=[12], flags=ND_GETBUF_FAIL)
+        self.assertRaises(BufferError, ndarray, ex)
+
+        # Request complex structure from a simple exporter. In this
+        # particular case the test object is not PEP-3118 compliant.
+        base = ndarray([9], [1])
+        ex = ndarray(base, getbuf=PyBUF_SIMPLE)
+        self.assertRaises(BufferError, ndarray, ex, getbuf=PyBUF_WRITABLE)
+        self.assertRaises(BufferError, ndarray, ex, getbuf=PyBUF_ND)
+        self.assertRaises(BufferError, ndarray, ex, getbuf=PyBUF_STRIDES)
+        self.assertRaises(BufferError, ndarray, ex, getbuf=PyBUF_C_CONTIGUOUS)
+        self.assertRaises(BufferError, ndarray, ex, getbuf=PyBUF_F_CONTIGUOUS)
+        self.assertRaises(BufferError, ndarray, ex, getbuf=PyBUF_ANY_CONTIGUOUS)
+        nd = ndarray(ex, getbuf=PyBUF_SIMPLE)
+
+    def test_ndarray_exceptions(self):
+        nd = ndarray([9], [1])
+        ndm = ndarray([9], [1], flags=ND_VAREXPORT)
+
+        # Initialization of a new ndarray or mutation of an existing array.
+        for c in (ndarray, nd.push, ndm.push):
+            # Invalid types.
+            self.assertRaises(TypeError, c, {1,2,3})
+            self.assertRaises(TypeError, c, [1,2,'3'])
+            self.assertRaises(TypeError, c, [1,2,(3,4)])
+            self.assertRaises(TypeError, c, [1,2,3], shape={3})
+            self.assertRaises(TypeError, c, [1,2,3], shape=[3], strides={1})
+            self.assertRaises(TypeError, c, [1,2,3], shape=[3], offset=[])
+            self.assertRaises(TypeError, c, [1], shape=[1], format={})
+            self.assertRaises(TypeError, c, [1], shape=[1], flags={})
+            self.assertRaises(TypeError, c, [1], shape=[1], getbuf={})
+
+            # ND_FORTRAN flag is only valid without strides.
+            self.assertRaises(TypeError, c, [1], shape=[1], strides=[1],
+                              flags=ND_FORTRAN)
+
+            # ND_PIL flag is only valid with ndim > 0.
+            self.assertRaises(TypeError, c, [1], shape=[], flags=ND_PIL)
+
+            # Invalid items.
+            self.assertRaises(ValueError, c, [], shape=[1])
+            self.assertRaises(ValueError, c, ['XXX'], shape=[1], format="L")
+            # Invalid combination of items and format.
+            self.assertRaises(struct.error, c, [1000], shape=[1], format="B")
+            self.assertRaises(ValueError, c, [1,(2,3)], shape=[2], format="B")
+            self.assertRaises(ValueError, c, [1,2,3], shape=[3], format="QL")
+
+            # Invalid ndim.
+            n = ND_MAX_NDIM+1
+            self.assertRaises(ValueError, c, [1]*n, shape=[1]*n)
+
+            # Invalid shape.
+            self.assertRaises(ValueError, c, [1], shape=[-1])
+            self.assertRaises(ValueError, c, [1,2,3], shape=['3'])
+            self.assertRaises(OverflowError, c, [1], shape=[2**128])
+            # prod(shape) * itemsize != len(items)
+            self.assertRaises(ValueError, c, [1,2,3,4,5], shape=[2,2], offset=3)
+
+            # Invalid strides.
+            self.assertRaises(ValueError, c, [1,2,3], shape=[3], strides=['1'])
+            self.assertRaises(OverflowError, c, [1], shape=[1],
+                              strides=[2**128])
+
+            # Invalid combination of strides and shape.
+            self.assertRaises(ValueError, c, [1,2], shape=[2,1], strides=[1])
+            # Invalid combination of strides and format.
+            self.assertRaises(ValueError, c, [1,2,3,4], shape=[2], strides=[3],
+                              format="L")
+
+            # Invalid offset.
+            self.assertRaises(ValueError, c, [1,2,3], shape=[3], offset=4)
+            self.assertRaises(ValueError, c, [1,2,3], shape=[1], offset=3,
+                              format="L")
+
+            # Invalid format.
+            self.assertRaises(ValueError, c, [1,2,3], shape=[3], format="")
+            self.assertRaises(struct.error, c, [(1,2,3)], shape=[1],
+                              format="@#$")
+
+            # Striding out of the memory bounds.
+            items = [1,2,3,4,5,6,7,8,9,10]
+            self.assertRaises(ValueError, c, items, shape=[2,3],
+                              strides=[-3, -2], offset=5)
+
+            # Constructing consumer: format argument invalid.
+            self.assertRaises(TypeError, c, bytearray(), format="Q")
+
+            # Constructing original base object: getbuf argument invalid.
+            self.assertRaises(TypeError, c, [1], shape=[1], getbuf=PyBUF_FULL)
+
+            # Shape argument is mandatory for original base objects.
+            self.assertRaises(TypeError, c, [1])
+
+
+        # PyBUF_WRITABLE request to read-only provider.
+        self.assertRaises(BufferError, ndarray, b'123', getbuf=PyBUF_WRITABLE)
+
+        # ND_VAREXPORT can only be specified during construction.
+        nd = ndarray([9], [1], flags=ND_VAREXPORT)
+        self.assertRaises(ValueError, nd.push, [1], [1], flags=ND_VAREXPORT)
+
+        # Invalid operation for consumers: push/pop
+        nd = ndarray(b'123')
+        self.assertRaises(BufferError, nd.push, [1], [1])
+        self.assertRaises(BufferError, nd.pop)
+
+        # ND_VAREXPORT not set: push/pop fail with exported buffers
+        nd = ndarray([9], [1])
+        nd.push([1], [1])
+        m = memoryview(nd)
+        self.assertRaises(BufferError, nd.push, [1], [1])
+        self.assertRaises(BufferError, nd.pop)
+        m.release()
+        nd.pop()
+
+        # Single remaining buffer: pop fails
+        self.assertRaises(BufferError, nd.pop)
+        del nd
+
+        # get_pointer()
+        self.assertRaises(TypeError, get_pointer, {}, [1,2,3])
+        self.assertRaises(TypeError, get_pointer, b'123', {})
+
+        nd = ndarray(list(range(100)), shape=[1]*100)
+        self.assertRaises(ValueError, get_pointer, nd, [5])
+
+        nd = ndarray(list(range(12)), shape=[3,4])
+        self.assertRaises(ValueError, get_pointer, nd, [2,3,4])
+        self.assertRaises(ValueError, get_pointer, nd, [3,3])
+        self.assertRaises(ValueError, get_pointer, nd, [-3,3])
+        self.assertRaises(OverflowError, get_pointer, nd, [1<<64,3])
+
+        # tolist() needs format
+        ex = ndarray([1,2,3], shape=[3], format='L')
+        nd = ndarray(ex, getbuf=PyBUF_SIMPLE)
+        self.assertRaises(ValueError, nd.tolist)
+
+        # memoryview_from_buffer()
+        ex1 = ndarray([1,2,3], shape=[3], format='L')
+        ex2 = ndarray(ex1)
+        nd = ndarray(ex2)
+        self.assertRaises(TypeError, nd.memoryview_from_buffer)
+
+        nd = ndarray([(1,)*200], shape=[1], format='L'*200)
+        self.assertRaises(TypeError, nd.memoryview_from_buffer)
+
+        n = ND_MAX_NDIM
+        nd = ndarray(list(range(n)), shape=[1]*n)
+        self.assertRaises(ValueError, nd.memoryview_from_buffer)
+
+        # get_contiguous()
+        nd = ndarray([1], shape=[1])
+        self.assertRaises(TypeError, get_contiguous, 1, 2, 3, 4, 5)
+        self.assertRaises(TypeError, get_contiguous, nd, "xyz", 'C')
+        self.assertRaises(OverflowError, get_contiguous, nd, 2**64, 'C')
+        self.assertRaises(TypeError, get_contiguous, nd, PyBUF_READ, 961)
+        self.assertRaises(UnicodeEncodeError, get_contiguous, nd, PyBUF_READ,
+                          '\u2007')
+
+        # cmp_contig()
+        nd = ndarray([1], shape=[1])
+        self.assertRaises(TypeError, cmp_contig, 1, 2, 3, 4, 5)
+        self.assertRaises(TypeError, cmp_contig, {}, nd)
+        self.assertRaises(TypeError, cmp_contig, nd, {})
+
+        # is_contiguous()
+        nd = ndarray([1], shape=[1])
+        self.assertRaises(TypeError, is_contiguous, 1, 2, 3, 4, 5)
+        self.assertRaises(TypeError, is_contiguous, {}, 'A')
+        self.assertRaises(TypeError, is_contiguous, nd, 201)
+
+    def test_ndarray_linked_list(self):
+        for perm in permutations(range(5)):
+            m = [0]*5
+            nd = ndarray([1,2,3], shape=[3], flags=ND_VAREXPORT)
+            m[0] = memoryview(nd)
+
+            for i in range(1, 5):
+                nd.push([1,2,3], shape=[3])
+                m[i] = memoryview(nd)
+
+            for i in range(5):
+                m[perm[i]].release()
+
+            self.assertRaises(BufferError, nd.pop)
+            del nd
+
+    def test_ndarray_format_scalar(self):
+        # ndim = 0: scalar
+        for fmt, scalar, _ in iter_format(0):
+            itemsize = struct.calcsize(fmt)
+            nd = ndarray(scalar, shape=(), format=fmt)
+            self.verify(nd, obj=None,
+                        itemsize=itemsize, fmt=fmt, readonly=1,
+                        ndim=0, shape=(), strides=(),
+                        lst=scalar)
+
+    def test_ndarray_format_shape(self):
+        # ndim = 1, shape = [n]
+        nitems =  randrange(1, 10)
+        for fmt, items, _ in iter_format(nitems):
+            itemsize = struct.calcsize(fmt)
+            for flags in (0, ND_PIL):
+                nd = ndarray(items, shape=[nitems], format=fmt, flags=flags)
+                self.verify(nd, obj=None,
+                            itemsize=itemsize, fmt=fmt, readonly=1,
+                            ndim=1, shape=(nitems,), strides=(itemsize,),
+                            lst=items)
+
+    def test_ndarray_format_strides(self):
+        # ndim = 1, strides
+        nitems = randrange(1, 30)
+        for fmt, items, _ in iter_format(nitems):
+            itemsize = struct.calcsize(fmt)
+            for step in range(-5, 5):
+                if step == 0:
+                    continue
+
+                shape = [len(items[::step])]
+                strides = [step*itemsize]
+                offset = itemsize*(nitems-1) if step < 0 else 0
+
+                for flags in (0, ND_PIL):
+                    nd = ndarray(items, shape=shape, strides=strides,
+                                 format=fmt, offset=offset, flags=flags)
+                    self.verify(nd, obj=None,
+                                itemsize=itemsize, fmt=fmt, readonly=1,
+                                ndim=1, shape=shape, strides=strides,
+                                lst=items[::step])
+
+    def test_ndarray_fortran(self):
+        items = [1,2,3,4,5,6,7,8,9,10,11,12]
+        ex = ndarray(items, shape=(3, 4), strides=(1, 3))
+        nd = ndarray(ex, getbuf=PyBUF_F_CONTIGUOUS|PyBUF_FORMAT)
+        self.assertEqual(nd.tolist(), farray(items, (3, 4)))
+
+    def test_ndarray_multidim(self):
+        for ndim in range(5):
+            shape_t = [randrange(2, 10) for _ in range(ndim)]
+            nitems = prod(shape_t)
+            for shape in permutations(shape_t):
+
+                fmt, items, _ = randitems(nitems)
+                itemsize = struct.calcsize(fmt)
+
+                for flags in (0, ND_PIL):
+                    if ndim == 0 and flags == ND_PIL:
+                        continue
+
+                    # C array
+                    nd = ndarray(items, shape=shape, format=fmt, flags=flags)
+
+                    strides = strides_from_shape(ndim, shape, itemsize, 'C')
+                    lst = carray(items, shape)
+                    self.verify(nd, obj=None,
+                                itemsize=itemsize, fmt=fmt, readonly=1,
+                                ndim=ndim, shape=shape, strides=strides,
+                                lst=lst)
+
+                    if is_memoryview_format(fmt):
+                        # memoryview: reconstruct strides
+                        ex = ndarray(items, shape=shape, format=fmt)
+                        nd = ndarray(ex, getbuf=PyBUF_CONTIG_RO|PyBUF_FORMAT)
+                        self.assertTrue(nd.strides == ())
+                        mv = nd.memoryview_from_buffer()
+                        self.verify(mv, obj=None,
+                                    itemsize=itemsize, fmt=fmt, readonly=1,
+                                    ndim=ndim, shape=shape, strides=strides,
+                                    lst=lst)
+
+                    # Fortran array
+                    nd = ndarray(items, shape=shape, format=fmt,
+                                 flags=flags|ND_FORTRAN)
+
+                    strides = strides_from_shape(ndim, shape, itemsize, 'F')
+                    lst = farray(items, shape)
+                    self.verify(nd, obj=None,
+                                itemsize=itemsize, fmt=fmt, readonly=1,
+                                ndim=ndim, shape=shape, strides=strides,
+                                lst=lst)
+
+    def test_ndarray_index_invalid(self):
+        # not writable
+        nd = ndarray([1], shape=[1])
+        self.assertRaises(TypeError, nd.__setitem__, 1, 8)
+        mv = memoryview(nd)
+        self.assertEqual(mv, nd)
+        self.assertRaises(TypeError, mv.__setitem__, 1, 8)
+
+        # cannot be deleted
+        nd = ndarray([1], shape=[1], flags=ND_WRITABLE)
+        self.assertRaises(TypeError, nd.__delitem__, 1)
+        mv = memoryview(nd)
+        self.assertEqual(mv, nd)
+        self.assertRaises(TypeError, mv.__delitem__, 1)
+
+        # overflow
+        nd = ndarray([1], shape=[1], flags=ND_WRITABLE)
+        self.assertRaises(OverflowError, nd.__getitem__, 1<<64)
+        self.assertRaises(OverflowError, nd.__setitem__, 1<<64, 8)
+        mv = memoryview(nd)
+        self.assertEqual(mv, nd)
+        self.assertRaises(IndexError, mv.__getitem__, 1<<64)
+        self.assertRaises(IndexError, mv.__setitem__, 1<<64, 8)
+
+        # format
+        items = [1,2,3,4,5,6,7,8]
+        nd = ndarray(items, shape=[len(items)], format="B", flags=ND_WRITABLE)
+        self.assertRaises(struct.error, nd.__setitem__, 2, 300)
+        self.assertRaises(ValueError, nd.__setitem__, 1, (100, 200))
+        mv = memoryview(nd)
+        self.assertEqual(mv, nd)
+        self.assertRaises(ValueError, mv.__setitem__, 2, 300)
+        self.assertRaises(TypeError, mv.__setitem__, 1, (100, 200))
+
+        items = [(1,2), (3,4), (5,6)]
+        nd = ndarray(items, shape=[len(items)], format="LQ", flags=ND_WRITABLE)
+        self.assertRaises(ValueError, nd.__setitem__, 2, 300)
+        self.assertRaises(struct.error, nd.__setitem__, 1, (b'\x001', 200))
+
+    def test_ndarray_index_scalar(self):
+        # scalar
+        nd = ndarray(1, shape=(), flags=ND_WRITABLE)
+        mv = memoryview(nd)
+        self.assertEqual(mv, nd)
+
+        x = nd[()];  self.assertEqual(x, 1)
+        x = nd[...]; self.assertEqual(x.tolist(), nd.tolist())
+
+        x = mv[()];  self.assertEqual(x, 1)
+        x = mv[...]; self.assertEqual(x.tolist(), nd.tolist())
+
+        self.assertRaises(TypeError, nd.__getitem__, 0)
+        self.assertRaises(TypeError, mv.__getitem__, 0)
+        self.assertRaises(TypeError, nd.__setitem__, 0, 8)
+        self.assertRaises(TypeError, mv.__setitem__, 0, 8)
+
+        self.assertEqual(nd.tolist(), 1)
+        self.assertEqual(mv.tolist(), 1)
+
+        nd[()] = 9; self.assertEqual(nd.tolist(), 9)
+        mv[()] = 9; self.assertEqual(mv.tolist(), 9)
+
+        nd[...] = 5; self.assertEqual(nd.tolist(), 5)
+        mv[...] = 5; self.assertEqual(mv.tolist(), 5)
+
+    def test_ndarray_index_null_strides(self):
+        ex = ndarray(list(range(2*4)), shape=[2, 4], flags=ND_WRITABLE)
+        nd = ndarray(ex, getbuf=PyBUF_CONTIG)
+
+        # Sub-views are only possible for full exporters.
+        self.assertRaises(BufferError, nd.__getitem__, 1)
+        # Same for slices.
+        self.assertRaises(BufferError, nd.__getitem__, slice(3,5,1))
+
+    def test_ndarray_index_getitem_single(self):
+        # getitem
+        for fmt, items, _ in iter_format(5):
+            nd = ndarray(items, shape=[5], format=fmt)
+            for i in range(-5, 5):
+                self.assertEqual(nd[i], items[i])
+
+            self.assertRaises(IndexError, nd.__getitem__, -6)
+            self.assertRaises(IndexError, nd.__getitem__, 5)
+
+            if is_memoryview_format(fmt):
+                mv = memoryview(nd)
+                self.assertEqual(mv, nd)
+                for i in range(-5, 5):
+                    self.assertEqual(mv[i], items[i])
+
+                self.assertRaises(IndexError, mv.__getitem__, -6)
+                self.assertRaises(IndexError, mv.__getitem__, 5)
+
+        # getitem with null strides
+        for fmt, items, _ in iter_format(5):
+            ex = ndarray(items, shape=[5], flags=ND_WRITABLE, format=fmt)
+            nd = ndarray(ex, getbuf=PyBUF_CONTIG|PyBUF_FORMAT)
+
+            for i in range(-5, 5):
+                self.assertEqual(nd[i], items[i])
+
+            if is_memoryview_format(fmt):
+                mv = nd.memoryview_from_buffer()
+                self.assertIs(mv.__eq__(nd), NotImplemented)
+                for i in range(-5, 5):
+                    self.assertEqual(mv[i], items[i])
+
+        # getitem with null format
+        items = [1,2,3,4,5]
+        ex = ndarray(items, shape=[5])
+        nd = ndarray(ex, getbuf=PyBUF_CONTIG_RO)
+        for i in range(-5, 5):
+            self.assertEqual(nd[i], items[i])
+
+        # getitem with null shape/strides/format
+        items = [1,2,3,4,5]
+        ex = ndarray(items, shape=[5])
+        nd = ndarray(ex, getbuf=PyBUF_SIMPLE)
+
+        for i in range(-5, 5):
+            self.assertEqual(nd[i], items[i])
+
+    def test_ndarray_index_setitem_single(self):
+        # assign single value
+        for fmt, items, single_item in iter_format(5):
+            nd = ndarray(items, shape=[5], format=fmt, flags=ND_WRITABLE)
+            for i in range(5):
+                items[i] = single_item
+                nd[i] = single_item
+            self.assertEqual(nd.tolist(), items)
+
+            self.assertRaises(IndexError, nd.__setitem__, -6, single_item)
+            self.assertRaises(IndexError, nd.__setitem__, 5, single_item)
+
+            if not is_memoryview_format(fmt):
+                continue
+
+            nd = ndarray(items, shape=[5], format=fmt, flags=ND_WRITABLE)
+            mv = memoryview(nd)
+            self.assertEqual(mv, nd)
+            for i in range(5):
+                items[i] = single_item
+                mv[i] = single_item
+            self.assertEqual(mv.tolist(), items)
+
+            self.assertRaises(IndexError, mv.__setitem__, -6, single_item)
+            self.assertRaises(IndexError, mv.__setitem__, 5, single_item)
+
+
+        # assign single value: lobject = robject
+        for fmt, items, single_item in iter_format(5):
+            nd = ndarray(items, shape=[5], format=fmt, flags=ND_WRITABLE)
+            for i in range(-5, 4):
+                items[i] = items[i+1]
+                nd[i] = nd[i+1]
+            self.assertEqual(nd.tolist(), items)
+
+            if not is_memoryview_format(fmt):
+                continue
+
+            nd = ndarray(items, shape=[5], format=fmt, flags=ND_WRITABLE)
+            mv = memoryview(nd)
+            self.assertEqual(mv, nd)
+            for i in range(-5, 4):
+                items[i] = items[i+1]
+                mv[i] = mv[i+1]
+            self.assertEqual(mv.tolist(), items)
+
+    def test_ndarray_index_getitem_multidim(self):
+        shape_t = (2, 3, 5)
+        nitems = prod(shape_t)
+        for shape in permutations(shape_t):
+
+            fmt, items, _ = randitems(nitems)
+
+            for flags in (0, ND_PIL):
+                # C array
+                nd = ndarray(items, shape=shape, format=fmt, flags=flags)
+                lst = carray(items, shape)
+
+                for i in range(-shape[0], shape[0]):
+                    self.assertEqual(lst[i], nd[i].tolist())
+                    for j in range(-shape[1], shape[1]):
+                        self.assertEqual(lst[i][j], nd[i][j].tolist())
+                        for k in range(-shape[2], shape[2]):
+                            self.assertEqual(lst[i][j][k], nd[i][j][k])
+
+                # Fortran array
+                nd = ndarray(items, shape=shape, format=fmt,
+                             flags=flags|ND_FORTRAN)
+                lst = farray(items, shape)
+
+                for i in range(-shape[0], shape[0]):
+                    self.assertEqual(lst[i], nd[i].tolist())
+                    for j in range(-shape[1], shape[1]):
+                        self.assertEqual(lst[i][j], nd[i][j].tolist())
+                        for k in range(shape[2], shape[2]):
+                            self.assertEqual(lst[i][j][k], nd[i][j][k])
+
+    def test_ndarray_sequence(self):
+        nd = ndarray(1, shape=())
+        self.assertRaises(TypeError, eval, "1 in nd", locals())
+        mv = memoryview(nd)
+        self.assertEqual(mv, nd)
+        self.assertRaises(TypeError, eval, "1 in mv", locals())
+
+        for fmt, items, _ in iter_format(5):
+            nd = ndarray(items, shape=[5], format=fmt)
+            for i, v in enumerate(nd):
+                self.assertEqual(v, items[i])
+                self.assertTrue(v in nd)
+
+            if is_memoryview_format(fmt):
+                mv = memoryview(nd)
+                for i, v in enumerate(mv):
+                    self.assertEqual(v, items[i])
+                    self.assertTrue(v in mv)
+
+    def test_ndarray_slice_invalid(self):
+        items = [1,2,3,4,5,6,7,8]
+
+        # rvalue is not an exporter
+        xl = ndarray(items, shape=[8], flags=ND_WRITABLE)
+        ml = memoryview(xl)
+        self.assertRaises(TypeError, xl.__setitem__, slice(0,8,1), items)
+        self.assertRaises(TypeError, ml.__setitem__, slice(0,8,1), items)
+
+        # rvalue is not a full exporter
+        xl = ndarray(items, shape=[8], flags=ND_WRITABLE)
+        ex = ndarray(items, shape=[8], flags=ND_WRITABLE)
+        xr = ndarray(ex, getbuf=PyBUF_ND)
+        self.assertRaises(BufferError, xl.__setitem__, slice(0,8,1), xr)
+
+        # zero step
+        nd = ndarray(items, shape=[8], format="L", flags=ND_WRITABLE)
+        mv = memoryview(nd)
+        self.assertRaises(ValueError, nd.__getitem__, slice(0,1,0))
+        self.assertRaises(ValueError, mv.__getitem__, slice(0,1,0))
+
+        nd = ndarray(items, shape=[2,4], format="L", flags=ND_WRITABLE)
+        mv = memoryview(nd)
+
+        self.assertRaises(ValueError, nd.__getitem__,
+                          (slice(0,1,1), slice(0,1,0)))
+        self.assertRaises(ValueError, nd.__getitem__,
+                          (slice(0,1,0), slice(0,1,1)))
+        self.assertRaises(TypeError, nd.__getitem__, "@%$")
+        self.assertRaises(TypeError, nd.__getitem__, ("@%$", slice(0,1,1)))
+        self.assertRaises(TypeError, nd.__getitem__, (slice(0,1,1), {}))
+
+        # memoryview: not implemented
+        self.assertRaises(NotImplementedError, mv.__getitem__,
+                          (slice(0,1,1), slice(0,1,0)))
+        self.assertRaises(TypeError, mv.__getitem__, "@%$")
+
+        # differing format
+        xl = ndarray(items, shape=[8], format="B", flags=ND_WRITABLE)
+        xr = ndarray(items, shape=[8], format="b")
+        ml = memoryview(xl)
+        mr = memoryview(xr)
+        self.assertRaises(ValueError, xl.__setitem__, slice(0,1,1), xr[7:8])
+        self.assertEqual(xl.tolist(), items)
+        self.assertRaises(ValueError, ml.__setitem__, slice(0,1,1), mr[7:8])
+        self.assertEqual(ml.tolist(), items)
+
+        # differing itemsize
+        xl = ndarray(items, shape=[8], format="B", flags=ND_WRITABLE)
+        yr = ndarray(items, shape=[8], format="L")
+        ml = memoryview(xl)
+        mr = memoryview(xr)
+        self.assertRaises(ValueError, xl.__setitem__, slice(0,1,1), xr[7:8])
+        self.assertEqual(xl.tolist(), items)
+        self.assertRaises(ValueError, ml.__setitem__, slice(0,1,1), mr[7:8])
+        self.assertEqual(ml.tolist(), items)
+
+        # differing ndim
+        xl = ndarray(items, shape=[2, 4], format="b", flags=ND_WRITABLE)
+        xr = ndarray(items, shape=[8], format="b")
+        ml = memoryview(xl)
+        mr = memoryview(xr)
+        self.assertRaises(ValueError, xl.__setitem__, slice(0,1,1), xr[7:8])
+        self.assertEqual(xl.tolist(), [[1,2,3,4], [5,6,7,8]])
+        self.assertRaises(NotImplementedError, ml.__setitem__, slice(0,1,1),
+                          mr[7:8])
+
+        # differing shape
+        xl = ndarray(items, shape=[8], format="b", flags=ND_WRITABLE)
+        xr = ndarray(items, shape=[8], format="b")
+        ml = memoryview(xl)
+        mr = memoryview(xr)
+        self.assertRaises(ValueError, xl.__setitem__, slice(0,2,1), xr[7:8])
+        self.assertEqual(xl.tolist(), items)
+        self.assertRaises(ValueError, ml.__setitem__, slice(0,2,1), mr[7:8])
+        self.assertEqual(ml.tolist(), items)
+
+        # _testbuffer.c module functions
+        self.assertRaises(TypeError, slice_indices, slice(0,1,2), {})
+        self.assertRaises(TypeError, slice_indices, "###########", 1)
+        self.assertRaises(ValueError, slice_indices, slice(0,1,0), 4)
+
+        x = ndarray(items, shape=[8], format="b", flags=ND_PIL)
+        self.assertRaises(TypeError, x.add_suboffsets)
+
+        ex = ndarray(items, shape=[8], format="B")
+        x = ndarray(ex, getbuf=PyBUF_SIMPLE)
+        self.assertRaises(TypeError, x.add_suboffsets)
+
+    def test_ndarray_slice_zero_shape(self):
+        items = [1,2,3,4,5,6,7,8,9,10,11,12]
+
+        x = ndarray(items, shape=[12], format="L", flags=ND_WRITABLE)
+        y = ndarray(items, shape=[12], format="L")
+        x[4:4] = y[9:9]
+        self.assertEqual(x.tolist(), items)
+
+        ml = memoryview(x)
+        mr = memoryview(y)
+        self.assertEqual(ml, x)
+        self.assertEqual(ml, y)
+        ml[4:4] = mr[9:9]
+        self.assertEqual(ml.tolist(), items)
+
+        x = ndarray(items, shape=[3, 4], format="L", flags=ND_WRITABLE)
+        y = ndarray(items, shape=[4, 3], format="L")
+        x[1:2, 2:2] = y[1:2, 3:3]
+        self.assertEqual(x.tolist(), carray(items, [3, 4]))
+
+    def test_ndarray_slice_multidim(self):
+        shape_t = (2, 3, 5)
+        ndim = len(shape_t)
+        nitems = prod(shape_t)
+        for shape in permutations(shape_t):
+
+            fmt, items, _ = randitems(nitems)
+            itemsize = struct.calcsize(fmt)
+
+            for flags in (0, ND_PIL):
+                nd = ndarray(items, shape=shape, format=fmt, flags=flags)
+                lst = carray(items, shape)
+
+                for slices in rslices_ndim(ndim, shape):
+
+                    listerr = None
+                    try:
+                        sliced = multislice(lst, slices)
+                    except Exception as e:
+                        listerr = e.__class__
+
+                    nderr = None
+                    try:
+                        ndsliced = nd[slices]
+                    except Exception as e:
+                        nderr = e.__class__
+
+                    if nderr or listerr:
+                        self.assertIs(nderr, listerr)
+                    else:
+                        self.assertEqual(ndsliced.tolist(), sliced)
+
+    def test_ndarray_slice_redundant_suboffsets(self):
+        shape_t = (2, 3, 5, 2)
+        ndim = len(shape_t)
+        nitems = prod(shape_t)
+        for shape in permutations(shape_t):
+
+            fmt, items, _ = randitems(nitems)
+            itemsize = struct.calcsize(fmt)
+
+            nd = ndarray(items, shape=shape, format=fmt)
+            nd.add_suboffsets()
+            ex = ndarray(items, shape=shape, format=fmt)
+            ex.add_suboffsets()
+            mv = memoryview(ex)
+            lst = carray(items, shape)
+
+            for slices in rslices_ndim(ndim, shape):
+
+                listerr = None
+                try:
+                    sliced = multislice(lst, slices)
+                except Exception as e:
+                    listerr = e.__class__
+
+                nderr = None
+                try:
+                    ndsliced = nd[slices]
+                except Exception as e:
+                    nderr = e.__class__
+
+                if nderr or listerr:
+                    self.assertIs(nderr, listerr)
+                else:
+                    self.assertEqual(ndsliced.tolist(), sliced)
+
+    def test_ndarray_slice_assign_single(self):
+        for fmt, items, _ in iter_format(5):
+            for lslice in genslices(5):
+                for rslice in genslices(5):
+                    for flags in (0, ND_PIL):
+
+                        f = flags|ND_WRITABLE
+                        nd = ndarray(items, shape=[5], format=fmt, flags=f)
+                        ex = ndarray(items, shape=[5], format=fmt, flags=f)
+                        mv = memoryview(ex)
+
+                        lsterr = None
+                        diff_structure = None
+                        lst = items[:]
+                        try:
+                            lval = lst[lslice]
+                            rval = lst[rslice]
+                            lst[lslice] = lst[rslice]
+                            diff_structure = len(lval) != len(rval)
+                        except Exception as e:
+                            lsterr = e.__class__
+
+                        nderr = None
+                        try:
+                            nd[lslice] = nd[rslice]
+                        except Exception as e:
+                            nderr = e.__class__
+
+                        if diff_structure: # ndarray cannot change shape
+                            self.assertIs(nderr, ValueError)
+                        else:
+                            self.assertEqual(nd.tolist(), lst)
+                            self.assertIs(nderr, lsterr)
+
+                        if not is_memoryview_format(fmt):
+                            continue
+
+                        mverr = None
+                        try:
+                            mv[lslice] = mv[rslice]
+                        except Exception as e:
+                            mverr = e.__class__
+
+                        if diff_structure: # memoryview cannot change shape
+                            self.assertIs(mverr, ValueError)
+                        else:
+                            self.assertEqual(mv.tolist(), lst)
+                            self.assertEqual(mv, nd)
+                            self.assertIs(mverr, lsterr)
+                            self.verify(mv, obj=ex,
+                              itemsize=nd.itemsize, fmt=fmt, readonly=0,
+                              ndim=nd.ndim, shape=nd.shape, strides=nd.strides,
+                              lst=nd.tolist())
+
+    def test_ndarray_slice_assign_multidim(self):
+        shape_t = (2, 3, 5)
+        ndim = len(shape_t)
+        nitems = prod(shape_t)
+        for shape in permutations(shape_t):
+
+            fmt, items, _ = randitems(nitems)
+
+            for flags in (0, ND_PIL):
+                for _ in range(ITERATIONS):
+                    lslices, rslices = randslice_from_shape(ndim, shape)
+
+                    nd = ndarray(items, shape=shape, format=fmt,
+                                 flags=flags|ND_WRITABLE)
+                    lst = carray(items, shape)
+
+                    listerr = None
+                    try:
+                        result = multislice_assign(lst, lst, lslices, rslices)
+                    except Exception as e:
+                        listerr = e.__class__
+
+                    nderr = None
+                    try:
+                        nd[lslices] = nd[rslices]
+                    except Exception as e:
+                        nderr = e.__class__
+
+                    if nderr or listerr:
+                        self.assertIs(nderr, listerr)
+                    else:
+                        self.assertEqual(nd.tolist(), result)
+
+    def test_ndarray_random(self):
+        # construction of valid arrays
+        for _ in range(ITERATIONS):
+            for fmt in fmtdict['@']:
+                itemsize = struct.calcsize(fmt)
+
+                t = rand_structure(itemsize, True, maxdim=MAXDIM,
+                                   maxshape=MAXSHAPE)
+                self.assertTrue(verify_structure(*t))
+                items = randitems_from_structure(fmt, t)
+
+                x = ndarray_from_structure(items, fmt, t)
+                xlist = x.tolist()
+
+                mv = memoryview(x)
+                if is_memoryview_format(fmt):
+                    mvlist = mv.tolist()
+                    self.assertEqual(mvlist, xlist)
+
+                if t[2] > 0:
+                    # ndim > 0: test against suboffsets representation.
+                    y = ndarray_from_structure(items, fmt, t, flags=ND_PIL)
+                    ylist = y.tolist()
+                    self.assertEqual(xlist, ylist)
+
+                    mv = memoryview(y)
+                    if is_memoryview_format(fmt):
+                        self.assertEqual(mv, y)
+                        mvlist = mv.tolist()
+                        self.assertEqual(mvlist, ylist)
+
+                if numpy_array:
+                    shape = t[3]
+                    if 0 in shape:
+                        continue # http://projects.scipy.org/numpy/ticket/1910
+                    z = numpy_array_from_structure(items, fmt, t)
+                    self.verify(x, obj=None,
+                                itemsize=z.itemsize, fmt=fmt, readonly=0,
+                                ndim=z.ndim, shape=z.shape, strides=z.strides,
+                                lst=z.tolist())
+
+    def test_ndarray_random_invalid(self):
+        # exceptions during construction of invalid arrays
+        for _ in range(ITERATIONS):
+            for fmt in fmtdict['@']:
+                itemsize = struct.calcsize(fmt)
+
+                t = rand_structure(itemsize, False, maxdim=MAXDIM,
+                                   maxshape=MAXSHAPE)
+                self.assertFalse(verify_structure(*t))
+                items = randitems_from_structure(fmt, t)
+
+                nderr = False
+                try:
+                    x = ndarray_from_structure(items, fmt, t)
+                except Exception as e:
+                    nderr = e.__class__
+                self.assertTrue(nderr)
+
+                if numpy_array:
+                    numpy_err = False
+                    try:
+                        y = numpy_array_from_structure(items, fmt, t)
+                    except Exception as e:
+                        numpy_err = e.__class__
+
+                    if 0: # http://projects.scipy.org/numpy/ticket/1910
+                        self.assertTrue(numpy_err)
+
+    def test_ndarray_random_slice_assign(self):
+        # valid slice assignments
+        for _ in range(ITERATIONS):
+            for fmt in fmtdict['@']:
+                itemsize = struct.calcsize(fmt)
+
+                lshape, rshape, lslices, rslices = \
+                    rand_aligned_slices(maxdim=MAXDIM, maxshape=MAXSHAPE)
+                tl = rand_structure(itemsize, True, shape=lshape)
+                tr = rand_structure(itemsize, True, shape=rshape)
+                self.assertTrue(verify_structure(*tl))
+                self.assertTrue(verify_structure(*tr))
+                litems = randitems_from_structure(fmt, tl)
+                ritems = randitems_from_structure(fmt, tr)
+
+                xl = ndarray_from_structure(litems, fmt, tl)
+                xr = ndarray_from_structure(ritems, fmt, tr)
+                xl[lslices] = xr[rslices]
+                xllist = xl.tolist()
+                xrlist = xr.tolist()
+
+                ml = memoryview(xl)
+                mr = memoryview(xr)
+                self.assertEqual(ml.tolist(), xllist)
+                self.assertEqual(mr.tolist(), xrlist)
+
+                if tl[2] > 0 and tr[2] > 0:
+                    # ndim > 0: test against suboffsets representation.
+                    yl = ndarray_from_structure(litems, fmt, tl, flags=ND_PIL)
+                    yr = ndarray_from_structure(ritems, fmt, tr, flags=ND_PIL)
+                    yl[lslices] = yr[rslices]
+                    yllist = yl.tolist()
+                    yrlist = yr.tolist()
+                    self.assertEqual(xllist, yllist)
+                    self.assertEqual(xrlist, yrlist)
+
+                    ml = memoryview(yl)
+                    mr = memoryview(yr)
+                    self.assertEqual(ml.tolist(), yllist)
+                    self.assertEqual(mr.tolist(), yrlist)
+
+                if numpy_array:
+                    if 0 in lshape or 0 in rshape:
+                        continue # http://projects.scipy.org/numpy/ticket/1910
+
+                    zl = numpy_array_from_structure(litems, fmt, tl)
+                    zr = numpy_array_from_structure(ritems, fmt, tr)
+                    zl[lslices] = zr[rslices]
+
+                    if not is_overlapping(tl) and not is_overlapping(tr):
+                        # Slice assignment of overlapping structures
+                        # is undefined in NumPy.
+                        self.verify(xl, obj=None,
+                                    itemsize=zl.itemsize, fmt=fmt, readonly=0,
+                                    ndim=zl.ndim, shape=zl.shape,
+                                    strides=zl.strides, lst=zl.tolist())
+
+                    self.verify(xr, obj=None,
+                                itemsize=zr.itemsize, fmt=fmt, readonly=0,
+                                ndim=zr.ndim, shape=zr.shape,
+                                strides=zr.strides, lst=zr.tolist())
+
+    def test_ndarray_re_export(self):
+        items = [1,2,3,4,5,6,7,8,9,10,11,12]
+
+        nd = ndarray(items, shape=[3,4], flags=ND_PIL)
+        ex = ndarray(nd)
+
+        self.assertTrue(ex.flags & ND_PIL)
+        self.assertIs(ex.obj, nd)
+        self.assertEqual(ex.suboffsets, (0, -1))
+        self.assertFalse(ex.c_contiguous)
+        self.assertFalse(ex.f_contiguous)
+        self.assertFalse(ex.contiguous)
+
+    def test_ndarray_zero_shape(self):
+        # zeros in shape
+        for flags in (0, ND_PIL):
+            nd = ndarray([1,2,3], shape=[0], flags=flags)
+            mv = memoryview(nd)
+            self.assertEqual(mv, nd)
+            self.assertEqual(nd.tolist(), [])
+            self.assertEqual(mv.tolist(), [])
+
+            nd = ndarray([1,2,3], shape=[0,3,3], flags=flags)
+            self.assertEqual(nd.tolist(), [])
+
+            nd = ndarray([1,2,3], shape=[3,0,3], flags=flags)
+            self.assertEqual(nd.tolist(), [[], [], []])
+
+            nd = ndarray([1,2,3], shape=[3,3,0], flags=flags)
+            self.assertEqual(nd.tolist(),
+                             [[[], [], []], [[], [], []], [[], [], []]])
+
+    def test_ndarray_zero_strides(self):
+        # zero strides
+        for flags in (0, ND_PIL):
+            nd = ndarray([1], shape=[5], strides=[0], flags=flags)
+            mv = memoryview(nd)
+            self.assertEqual(mv, nd)
+            self.assertEqual(nd.tolist(), [1, 1, 1, 1, 1])
+            self.assertEqual(mv.tolist(), [1, 1, 1, 1, 1])
+
+    def test_ndarray_offset(self):
+        nd = ndarray(list(range(20)), shape=[3], offset=7)
+        self.assertEqual(nd.offset, 7)
+        self.assertEqual(nd.tolist(), [7,8,9])
+
+    def test_ndarray_memoryview_from_buffer(self):
+        for flags in (0, ND_PIL):
+            nd = ndarray(list(range(3)), shape=[3], flags=flags)
+            m = nd.memoryview_from_buffer()
+            self.assertEqual(m, nd)
+
+    def test_ndarray_get_pointer(self):
+        for flags in (0, ND_PIL):
+            nd = ndarray(list(range(3)), shape=[3], flags=flags)
+            for i in range(3):
+                self.assertEqual(nd[i], get_pointer(nd, [i]))
+
+    def test_ndarray_tolist_null_strides(self):
+        ex = ndarray(list(range(20)), shape=[2,2,5])
+
+        nd = ndarray(ex, getbuf=PyBUF_ND|PyBUF_FORMAT)
+        self.assertEqual(nd.tolist(), ex.tolist())
+
+        m = memoryview(ex)
+        self.assertEqual(m.tolist(), ex.tolist())
+
+    def test_ndarray_cmp_contig(self):
+
+        self.assertFalse(cmp_contig(b"123", b"456"))
+
+        x = ndarray(list(range(12)), shape=[3,4])
+        y = ndarray(list(range(12)), shape=[4,3])
+        self.assertFalse(cmp_contig(x, y))
+
+        x = ndarray([1], shape=[1], format="B")
+        self.assertTrue(cmp_contig(x, b'\x01'))
+        self.assertTrue(cmp_contig(b'\x01', x))
+
+    def test_ndarray_hash(self):
+
+        a = array.array('L', [1,2,3])
+        nd = ndarray(a)
+        self.assertRaises(ValueError, hash, nd)
+
+        # one-dimensional
+        b = bytes(list(range(12)))
+
+        nd = ndarray(list(range(12)), shape=[12])
+        self.assertEqual(hash(nd), hash(b))
+
+        # C-contiguous
+        nd = ndarray(list(range(12)), shape=[3,4])
+        self.assertEqual(hash(nd), hash(b))
+
+        nd = ndarray(list(range(12)), shape=[3,2,2])
+        self.assertEqual(hash(nd), hash(b))
+
+        # Fortran contiguous
+        b = bytes(transpose(list(range(12)), shape=[4,3]))
+        nd = ndarray(list(range(12)), shape=[3,4], flags=ND_FORTRAN)
+        self.assertEqual(hash(nd), hash(b))
+
+        b = bytes(transpose(list(range(12)), shape=[2,3,2]))
+        nd = ndarray(list(range(12)), shape=[2,3,2], flags=ND_FORTRAN)
+        self.assertEqual(hash(nd), hash(b))
+
+        # suboffsets
+        b = bytes(list(range(12)))
+        nd = ndarray(list(range(12)), shape=[2,2,3], flags=ND_PIL)
+        self.assertEqual(hash(nd), hash(b))
+
+        # non-byte formats
+        nd = ndarray(list(range(12)), shape=[2,2,3], format='L')
+        self.assertEqual(hash(nd), hash(nd.tobytes()))
+
+    def test_memoryview_construction(self):
+
+        items_shape = [(9, []), ([1,2,3], [3]), (list(range(2*3*5)), [2,3,5])]
+
+        # NumPy style, C-contiguous:
+        for items, shape in items_shape:
+
+            # From PEP-3118 compliant exporter:
+            ex = ndarray(items, shape=shape)
+            m = memoryview(ex)
+            self.assertTrue(m.c_contiguous)
+            self.assertTrue(m.contiguous)
+
+            ndim = len(shape)
+            strides = strides_from_shape(ndim, shape, 1, 'C')
+            lst = carray(items, shape)
+
+            self.verify(m, obj=ex,
+                        itemsize=1, fmt='B', readonly=1,
+                        ndim=ndim, shape=shape, strides=strides,
+                        lst=lst)
+
+            # From memoryview:
+            m2 = memoryview(m)
+            self.verify(m2, obj=ex,
+                        itemsize=1, fmt='B', readonly=1,
+                        ndim=ndim, shape=shape, strides=strides,
+                        lst=lst)
+
+            # PyMemoryView_FromBuffer(): no strides
+            nd = ndarray(ex, getbuf=PyBUF_CONTIG_RO|PyBUF_FORMAT)
+            self.assertEqual(nd.strides, ())
+            m = nd.memoryview_from_buffer()
+            self.verify(m, obj=None,
+                        itemsize=1, fmt='B', readonly=1,
+                        ndim=ndim, shape=shape, strides=strides,
+                        lst=lst)
+
+            # PyMemoryView_FromBuffer(): no format, shape, strides
+            nd = ndarray(ex, getbuf=PyBUF_SIMPLE)
+            self.assertEqual(nd.format, '')
+            self.assertEqual(nd.shape, ())
+            self.assertEqual(nd.strides, ())
+            m = nd.memoryview_from_buffer()
+
+            lst = [items] if ndim == 0 else items
+            self.verify(m, obj=None,
+                        itemsize=1, fmt='B', readonly=1,
+                        ndim=1, shape=[ex.nbytes], strides=(1,),
+                        lst=lst)
+
+        # NumPy style, Fortran contiguous:
+        for items, shape in items_shape:
+
+            # From PEP-3118 compliant exporter:
+            ex = ndarray(items, shape=shape, flags=ND_FORTRAN)
+            m = memoryview(ex)
+            self.assertTrue(m.f_contiguous)
+            self.assertTrue(m.contiguous)
+
+            ndim = len(shape)
+            strides = strides_from_shape(ndim, shape, 1, 'F')
+            lst = farray(items, shape)
+
+            self.verify(m, obj=ex,
+                        itemsize=1, fmt='B', readonly=1,
+                        ndim=ndim, shape=shape, strides=strides,
+                        lst=lst)
+
+            # From memoryview:
+            m2 = memoryview(m)
+            self.verify(m2, obj=ex,
+                        itemsize=1, fmt='B', readonly=1,
+                        ndim=ndim, shape=shape, strides=strides,
+                        lst=lst)
+
+        # PIL style:
+        for items, shape in items_shape[1:]:
+
+            # From PEP-3118 compliant exporter:
+            ex = ndarray(items, shape=shape, flags=ND_PIL)
+            m = memoryview(ex)
+
+            ndim = len(shape)
+            lst = carray(items, shape)
+
+            self.verify(m, obj=ex,
+                        itemsize=1, fmt='B', readonly=1,
+                        ndim=ndim, shape=shape, strides=ex.strides,
+                        lst=lst)
+
+            # From memoryview:
+            m2 = memoryview(m)
+            self.verify(m2, obj=ex,
+                        itemsize=1, fmt='B', readonly=1,
+                        ndim=ndim, shape=shape, strides=ex.strides,
+                        lst=lst)
+
+        # Invalid number of arguments:
+        self.assertRaises(TypeError, memoryview, b'9', 'x')
+        # Not a buffer provider:
+        self.assertRaises(TypeError, memoryview, {})
+        # Non-compliant buffer provider:
+        ex = ndarray([1,2,3], shape=[3])
+        nd = ndarray(ex, getbuf=PyBUF_SIMPLE)
+        self.assertRaises(BufferError, memoryview, nd)
+        nd = ndarray(ex, getbuf=PyBUF_CONTIG_RO|PyBUF_FORMAT)
+        self.assertRaises(BufferError, memoryview, nd)
+
+        # ndim > 64
+        nd = ndarray([1]*128, shape=[1]*128, format='L')
+        self.assertRaises(ValueError, memoryview, nd)
+        self.assertRaises(ValueError, nd.memoryview_from_buffer)
+        self.assertRaises(ValueError, get_contiguous, nd, PyBUF_READ, 'C')
+        self.assertRaises(ValueError, get_contiguous, nd, PyBUF_READ, 'F')
+        self.assertRaises(ValueError, get_contiguous, nd[::-1], PyBUF_READ, 'C')
+
+    def test_memoryview_cast_zero_shape(self):
+        # Casts are undefined if shape contains zeros. These arrays are
+        # regarded as C-contiguous by Numpy and PyBuffer_GetContiguous(),
+        # so they are not caught by the test for C-contiguity in memory_cast().
+        items = [1,2,3]
+        for shape in ([0,3,3], [3,0,3], [0,3,3]):
+            ex = ndarray(items, shape=shape)
+            self.assertTrue(ex.c_contiguous)
+            msrc = memoryview(ex)
+            self.assertRaises(TypeError, msrc.cast, 'c')
+
+    def test_memoryview_struct_module(self):
+
+        class INT(object):
+            def __init__(self, val):
+                self.val = val
+            def __int__(self):
+                return self.val
+
+        class IDX(object):
+            def __init__(self, val):
+                self.val = val
+            def __index__(self):
+                return self.val
+
+        def f(): return 7
+
+        values = [INT(9), IDX(9),
+                  2.2+3j, Decimal("-21.1"), 12.2, Fraction(5, 2),
+                  [1,2,3], {4,5,6}, {7:8}, (), (9,),
+                  True, False, None, NotImplemented,
+                  b'a', b'abc', bytearray(b'a'), bytearray(b'abc'),
+                  'a', 'abc', r'a', r'abc',
+                  f, lambda x: x]
+
+        for fmt, items, item in iter_format(10, 'memoryview'):
+            ex = ndarray(items, shape=[10], format=fmt, flags=ND_WRITABLE)
+            nd = ndarray(items, shape=[10], format=fmt, flags=ND_WRITABLE)
+            m = memoryview(ex)
+
+            struct.pack_into(fmt, nd, 0, item)
+            m[0] = item
+            self.assertEqual(m[0], nd[0])
+
+            itemsize = struct.calcsize(fmt)
+            if 'P' in fmt:
+                continue
+
+            for v in values:
+                struct_err = None
+                try:
+                    struct.pack_into(fmt, nd, itemsize, v)
+                except struct.error:
+                    struct_err = struct.error
+
+                mv_err = None
+                try:
+                    m[1] = v
+                except (TypeError, ValueError) as e:
+                    mv_err = e.__class__
+
+                if struct_err or mv_err:
+                    self.assertIsNot(struct_err, None)
+                    self.assertIsNot(mv_err, None)
+                else:
+                    self.assertEqual(m[1], nd[1])
+
+    def test_memoryview_cast_zero_strides(self):
+        # Casts are undefined if strides contains zeros. These arrays are
+        # (sometimes!) regarded as C-contiguous by Numpy, but not by
+        # PyBuffer_GetContiguous().
+        ex = ndarray([1,2,3], shape=[3], strides=[0])
+        self.assertFalse(ex.c_contiguous)
+        msrc = memoryview(ex)
+        self.assertRaises(TypeError, msrc.cast, 'c')
+
+    def test_memoryview_cast_invalid(self):
+        # invalid format
+        for sfmt in NON_BYTE_FORMAT:
+            sformat = '@' + sfmt if randrange(2) else sfmt
+            ssize = struct.calcsize(sformat)
+            for dfmt in NON_BYTE_FORMAT:
+                dformat = '@' + dfmt if randrange(2) else dfmt
+                dsize = struct.calcsize(dformat)
+                ex = ndarray(list(range(32)), shape=[32//ssize], format=sformat)
+                msrc = memoryview(ex)
+                self.assertRaises(TypeError, msrc.cast, dfmt, [32//dsize])
+
+        for sfmt, sitems, _ in iter_format(1):
+            ex = ndarray(sitems, shape=[1], format=sfmt)
+            msrc = memoryview(ex)
+            for dfmt, _, _ in iter_format(1):
+                if (not is_memoryview_format(sfmt) or
+                    not is_memoryview_format(dfmt)):
+                    self.assertRaises(ValueError, msrc.cast, dfmt,
+                                      [32//dsize])
+                else:
+                    if not is_byte_format(sfmt) and not is_byte_format(dfmt):
+                        self.assertRaises(TypeError, msrc.cast, dfmt,
+                                          [32//dsize])
+
+        # invalid shape
+        size_h = struct.calcsize('h')
+        size_d = struct.calcsize('d')
+        ex = ndarray(list(range(2*2*size_d)), shape=[2,2,size_d], format='h')
+        msrc = memoryview(ex)
+        self.assertRaises(TypeError, msrc.cast, shape=[2,2,size_h], format='d')
+
+        ex = ndarray(list(range(120)), shape=[1,2,3,4,5])
+        m = memoryview(ex)
+
+        # incorrect number of args
+        self.assertRaises(TypeError, m.cast)
+        self.assertRaises(TypeError, m.cast, 1, 2, 3)
+
+        # incorrect dest format type
+        self.assertRaises(TypeError, m.cast, {})
+
+        # incorrect dest format
+        self.assertRaises(ValueError, m.cast, "X")
+        self.assertRaises(ValueError, m.cast, "@X")
+        self.assertRaises(ValueError, m.cast, "@XY")
+
+        # dest format not implemented
+        self.assertRaises(ValueError, m.cast, "=B")
+        self.assertRaises(ValueError, m.cast, "!L")
+        self.assertRaises(ValueError, m.cast, "<P")
+        self.assertRaises(ValueError, m.cast, ">l")
+        self.assertRaises(ValueError, m.cast, "BI")
+        self.assertRaises(ValueError, m.cast, "xBI")
+
+        # src format not implemented
+        ex = ndarray([(1,2), (3,4)], shape=[2], format="II")
+        m = memoryview(ex)
+        self.assertRaises(NotImplementedError, m.__getitem__, 0)
+        self.assertRaises(NotImplementedError, m.__setitem__, 0, 8)
+        self.assertRaises(NotImplementedError, m.tolist)
+
+        # incorrect shape type
+        ex = ndarray(list(range(120)), shape=[1,2,3,4,5])
+        m = memoryview(ex)
+        self.assertRaises(TypeError, m.cast, "B", shape={})
+
+        # incorrect shape elements
+        ex = ndarray(list(range(120)), shape=[2*3*4*5])
+        m = memoryview(ex)
+        self.assertRaises(OverflowError, m.cast, "B", shape=[2**64])
+        self.assertRaises(ValueError, m.cast, "B", shape=[-1])
+        self.assertRaises(ValueError, m.cast, "B", shape=[2,3,4,5,6,7,-1])
+        self.assertRaises(ValueError, m.cast, "B", shape=[2,3,4,5,6,7,0])
+        self.assertRaises(TypeError, m.cast, "B", shape=[2,3,4,5,6,7,'x'])
+
+        # N-D -> N-D cast
+        ex = ndarray(list([9 for _ in range(3*5*7*11)]), shape=[3,5,7,11])
+        m = memoryview(ex)
+        self.assertRaises(TypeError, m.cast, "I", shape=[2,3,4,5])
+
+        # cast with ndim > 64
+        nd = ndarray(list(range(128)), shape=[128], format='I')
+        m = memoryview(nd)
+        self.assertRaises(ValueError, m.cast, 'I', [1]*128)
+
+        # view->len not a multiple of itemsize
+        ex = ndarray(list([9 for _ in range(3*5*7*11)]), shape=[3*5*7*11])
+        m = memoryview(ex)
+        self.assertRaises(TypeError, m.cast, "I", shape=[2,3,4,5])
+
+        # product(shape) * itemsize != buffer size
+        ex = ndarray(list([9 for _ in range(3*5*7*11)]), shape=[3*5*7*11])
+        m = memoryview(ex)
+        self.assertRaises(TypeError, m.cast, "B", shape=[2,3,4,5])
+
+        # product(shape) * itemsize overflow
+        nd = ndarray(list(range(128)), shape=[128], format='I')
+        m1 = memoryview(nd)
+        nd = ndarray(list(range(128)), shape=[128], format='B')
+        m2 = memoryview(nd)
+        if sys.maxsize == 2**63-1:
+            self.assertRaises(TypeError, m1.cast, 'B',
+                              [7, 7, 73, 127, 337, 92737, 649657])
+            self.assertRaises(ValueError, m1.cast, 'B',
+                              [2**20, 2**20, 2**10, 2**10, 2**3])
+            self.assertRaises(ValueError, m2.cast, 'I',
+                              [2**20, 2**20, 2**10, 2**10, 2**1])
+        else:
+            self.assertRaises(TypeError, m1.cast, 'B',
+                              [1, 2147483647])
+            self.assertRaises(ValueError, m1.cast, 'B',
+                              [2**10, 2**10, 2**5, 2**5, 2**1])
+            self.assertRaises(ValueError, m2.cast, 'I',
+                              [2**10, 2**10, 2**5, 2**3, 2**1])
+
+    def test_memoryview_cast(self):
+        bytespec = (
+          ('B', lambda ex: list(ex.tobytes())),
+          ('b', lambda ex: [x-256 if x > 127 else x for x in list(ex.tobytes())]),
+          ('c', lambda ex: [bytes(chr(x), 'latin-1') for x in list(ex.tobytes())]),
+        )
+
+        def iter_roundtrip(ex, m, items, fmt):
+            srcsize = struct.calcsize(fmt)
+            for bytefmt, to_bytelist in bytespec:
+
+                m2 = m.cast(bytefmt)
+                lst = to_bytelist(ex)
+                self.verify(m2, obj=ex,
+                            itemsize=1, fmt=bytefmt, readonly=0,
+                            ndim=1, shape=[31*srcsize], strides=(1,),
+                            lst=lst, cast=True)
+
+                m3 = m2.cast(fmt)
+                self.assertEqual(m3, ex)
+                lst = ex.tolist()
+                self.verify(m3, obj=ex,
+                            itemsize=srcsize, fmt=fmt, readonly=0,
+                            ndim=1, shape=[31], strides=(srcsize,),
+                            lst=lst, cast=True)
+
+        # cast from ndim = 0 to ndim = 1
+        srcsize = struct.calcsize('I')
+        ex = ndarray(9, shape=[], format='I')
+        destitems, destshape = cast_items(ex, 'B', 1)
+        m = memoryview(ex)
+        m2 = m.cast('B')
+        self.verify(m2, obj=ex,
+                    itemsize=1, fmt='B', readonly=1,
+                    ndim=1, shape=destshape, strides=(1,),
+                    lst=destitems, cast=True)
+
+        # cast from ndim = 1 to ndim = 0
+        destsize = struct.calcsize('I')
+        ex = ndarray([9]*destsize, shape=[destsize], format='B')
+        destitems, destshape = cast_items(ex, 'I', destsize, shape=[])
+        m = memoryview(ex)
+        m2 = m.cast('I', shape=[])
+        self.verify(m2, obj=ex,
+                    itemsize=destsize, fmt='I', readonly=1,
+                    ndim=0, shape=(), strides=(),
+                    lst=destitems, cast=True)
+
+        # array.array: roundtrip to/from bytes
+        for fmt, items, _ in iter_format(31, 'array'):
+            ex = array.array(fmt, items)
+            m = memoryview(ex)
+            iter_roundtrip(ex, m, items, fmt)
+
+        # ndarray: roundtrip to/from bytes
+        for fmt, items, _ in iter_format(31, 'memoryview'):
+            ex = ndarray(items, shape=[31], format=fmt, flags=ND_WRITABLE)
+            m = memoryview(ex)
+            iter_roundtrip(ex, m, items, fmt)
+
+    def test_memoryview_cast_1D_ND(self):
+        # Cast between C-contiguous buffers. At least one buffer must
+        # be 1D, at least one format must be 'c', 'b' or 'B'.
+        for _tshape in gencastshapes():
+            for char in fmtdict['@']:
+                tfmt = ('', '@')[randrange(2)] + char
+                tsize = struct.calcsize(tfmt)
+                n = prod(_tshape) * tsize
+                obj = 'memoryview' if is_byte_format(tfmt) else 'bytefmt'
+                for fmt, items, _ in iter_format(n, obj):
+                    size = struct.calcsize(fmt)
+                    shape = [n] if n > 0 else []
+                    tshape = _tshape + [size]
+
+                    ex = ndarray(items, shape=shape, format=fmt)
+                    m = memoryview(ex)
+
+                    titems, tshape = cast_items(ex, tfmt, tsize, shape=tshape)
+
+                    if titems is None:
+                        self.assertRaises(TypeError, m.cast, tfmt, tshape)
+                        continue
+                    if titems == 'nan':
+                        continue # NaNs in lists are a recipe for trouble.
+
+                    # 1D -> ND
+                    nd = ndarray(titems, shape=tshape, format=tfmt)
+
+                    m2 = m.cast(tfmt, shape=tshape)
+                    ndim = len(tshape)
+                    strides = nd.strides
+                    lst = nd.tolist()
+                    self.verify(m2, obj=ex,
+                                itemsize=tsize, fmt=tfmt, readonly=1,
+                                ndim=ndim, shape=tshape, strides=strides,
+                                lst=lst, cast=True)
+
+                    # ND -> 1D
+                    m3 = m2.cast(fmt)
+                    m4 = m2.cast(fmt, shape=shape)
+                    ndim = len(shape)
+                    strides = ex.strides
+                    lst = ex.tolist()
+
+                    self.verify(m3, obj=ex,
+                                itemsize=size, fmt=fmt, readonly=1,
+                                ndim=ndim, shape=shape, strides=strides,
+                                lst=lst, cast=True)
+
+                    self.verify(m4, obj=ex,
+                                itemsize=size, fmt=fmt, readonly=1,
+                                ndim=ndim, shape=shape, strides=strides,
+                                lst=lst, cast=True)
+
+    def test_memoryview_tolist(self):
+
+        # Most tolist() tests are in self.verify() etc.
+
+        a = array.array('h', list(range(-6, 6)))
+        m = memoryview(a)
+        self.assertEqual(m, a)
+        self.assertEqual(m.tolist(), a.tolist())
+
+        a = a[2::3]
+        m = m[2::3]
+        self.assertEqual(m, a)
+        self.assertEqual(m.tolist(), a.tolist())
+
+        ex = ndarray(list(range(2*3*5*7*11)), shape=[11,2,7,3,5], format='L')
+        m = memoryview(ex)
+        self.assertEqual(m.tolist(), ex.tolist())
+
+        ex = ndarray([(2, 5), (7, 11)], shape=[2], format='lh')
+        m = memoryview(ex)
+        self.assertRaises(NotImplementedError, m.tolist)
+
+        ex = ndarray([b'12345'], shape=[1], format="s")
+        m = memoryview(ex)
+        self.assertRaises(NotImplementedError, m.tolist)
+
+        ex = ndarray([b"a",b"b",b"c",b"d",b"e",b"f"], shape=[2,3], format='s')
+        m = memoryview(ex)
+        self.assertRaises(NotImplementedError, m.tolist)
+
+    def test_memoryview_repr(self):
+        m = memoryview(bytearray(9))
+        r = m.__repr__()
+        self.assertTrue(r.startswith("<memory"))
+
+        m.release()
+        r = m.__repr__()
+        self.assertTrue(r.startswith("<released"))
+
+    def test_memoryview_sequence(self):
+
+        for fmt in ('d', 'f'):
+            inf = float(3e400)
+            ex = array.array(fmt, [1.0, inf, 3.0])
+            m = memoryview(ex)
+            self.assertIn(1.0, m)
+            self.assertIn(5e700, m)
+            self.assertIn(3.0, m)
+
+        ex = ndarray(9.0, [], format='f')
+        m = memoryview(ex)
+        self.assertRaises(TypeError, eval, "9.0 in m", locals())
+
+    def test_memoryview_index(self):
+
+        # ndim = 0
+        ex = ndarray(12.5, shape=[], format='d')
+        m = memoryview(ex)
+        self.assertEqual(m[()], 12.5)
+        self.assertEqual(m[...], m)
+        self.assertEqual(m[...], ex)
+        self.assertRaises(TypeError, m.__getitem__, 0)
+
+        ex = ndarray((1,2,3), shape=[], format='iii')
+        m = memoryview(ex)
+        self.assertRaises(NotImplementedError, m.__getitem__, ())
+
+        # range
+        ex = ndarray(list(range(7)), shape=[7], flags=ND_WRITABLE)
+        m = memoryview(ex)
+
+        self.assertRaises(IndexError, m.__getitem__, 2**64)
+        self.assertRaises(TypeError, m.__getitem__, 2.0)
+        self.assertRaises(TypeError, m.__getitem__, 0.0)
+
+        # out of bounds
+        self.assertRaises(IndexError, m.__getitem__, -8)
+        self.assertRaises(IndexError, m.__getitem__, 8)
+
+        # Not implemented: multidimensional sub-views
+        ex = ndarray(list(range(12)), shape=[3,4], flags=ND_WRITABLE)
+        m = memoryview(ex)
+
+        self.assertRaises(NotImplementedError, m.__getitem__, 0)
+        self.assertRaises(NotImplementedError, m.__setitem__, 0, 9)
+        self.assertRaises(NotImplementedError, m.__getitem__, 0)
+
+    def test_memoryview_assign(self):
+
+        # ndim = 0
+        ex = ndarray(12.5, shape=[], format='f', flags=ND_WRITABLE)
+        m = memoryview(ex)
+        m[()] = 22.5
+        self.assertEqual(m[()], 22.5)
+        m[...] = 23.5
+        self.assertEqual(m[()], 23.5)
+        self.assertRaises(TypeError, m.__setitem__, 0, 24.7)
+
+        # read-only
+        ex = ndarray(list(range(7)), shape=[7])
+        m = memoryview(ex)
+        self.assertRaises(TypeError, m.__setitem__, 2, 10)
+
+        # range
+        ex = ndarray(list(range(7)), shape=[7], flags=ND_WRITABLE)
+        m = memoryview(ex)
+
+        self.assertRaises(IndexError, m.__setitem__, 2**64, 9)
+        self.assertRaises(TypeError, m.__setitem__, 2.0, 10)
+        self.assertRaises(TypeError, m.__setitem__, 0.0, 11)
+
+        # out of bounds
+        self.assertRaises(IndexError, m.__setitem__, -8, 20)
+        self.assertRaises(IndexError, m.__setitem__, 8, 25)
+
+        # pack_single() success:
+        for fmt in fmtdict['@']:
+            if fmt == 'c' or fmt == '?':
+                continue
+            ex = ndarray([1,2,3], shape=[3], format=fmt, flags=ND_WRITABLE)
+            m = memoryview(ex)
+            i = randrange(-3, 3)
+            m[i] = 8
+            self.assertEqual(m[i], 8)
+            self.assertEqual(m[i], ex[i])
+
+        ex = ndarray([b'1', b'2', b'3'], shape=[3], format='c',
+                     flags=ND_WRITABLE)
+        m = memoryview(ex)
+        m[2] = b'9'
+        self.assertEqual(m[2], b'9')
+
+        ex = ndarray([True, False, True], shape=[3], format='?',
+                     flags=ND_WRITABLE)
+        m = memoryview(ex)
+        m[1] = True
+        self.assertEqual(m[1], True)
+
+        # pack_single() exceptions:
+        nd = ndarray([b'x'], shape=[1], format='c', flags=ND_WRITABLE)
+        m = memoryview(nd)
+        self.assertRaises(TypeError, m.__setitem__, 0, 100)
+
+        ex = ndarray(list(range(120)), shape=[1,2,3,4,5], flags=ND_WRITABLE)
+        m1 = memoryview(ex)
+
+        for fmt, _range in fmtdict['@'].items():
+            if (fmt == '?'): # PyObject_IsTrue() accepts anything
+                continue
+            if fmt == 'c': # special case tested above
+                continue
+            m2 = m1.cast(fmt)
+            lo, hi = _range
+            if fmt == 'd' or fmt == 'f':
+                lo, hi = -2**1024, 2**1024
+            if fmt != 'P': # PyLong_AsVoidPtr() accepts negative numbers
+                self.assertRaises(ValueError, m2.__setitem__, 0, lo-1)
+                self.assertRaises(TypeError, m2.__setitem__, 0, "xyz")
+            self.assertRaises(ValueError, m2.__setitem__, 0, hi)
+
+        # invalid item
+        m2 = m1.cast('c')
+        self.assertRaises(ValueError, m2.__setitem__, 0, b'\xff\xff')
+
+        # format not implemented
+        ex = ndarray(list(range(1)), shape=[1], format="xL", flags=ND_WRITABLE)
+        m = memoryview(ex)
+        self.assertRaises(NotImplementedError, m.__setitem__, 0, 1)
+
+        ex = ndarray([b'12345'], shape=[1], format="s", flags=ND_WRITABLE)
+        m = memoryview(ex)
+        self.assertRaises(NotImplementedError, m.__setitem__, 0, 1)
+
+        # Not implemented: multidimensional sub-views
+        ex = ndarray(list(range(12)), shape=[3,4], flags=ND_WRITABLE)
+        m = memoryview(ex)
+
+        self.assertRaises(NotImplementedError, m.__setitem__, 0, [2, 3])
+
+    def test_memoryview_slice(self):
+
+        ex = ndarray(list(range(12)), shape=[12], flags=ND_WRITABLE)
+        m = memoryview(ex)
+
+        # zero step
+        self.assertRaises(ValueError, m.__getitem__, slice(0,2,0))
+        self.assertRaises(ValueError, m.__setitem__, slice(0,2,0),
+                          bytearray([1,2]))
+
+        # invalid slice key
+        self.assertRaises(TypeError, m.__getitem__, ())
+
+        # multidimensional slices
+        ex = ndarray(list(range(12)), shape=[12], flags=ND_WRITABLE)
+        m = memoryview(ex)
+
+        self.assertRaises(NotImplementedError, m.__getitem__,
+                          (slice(0,2,1), slice(0,2,1)))
+        self.assertRaises(NotImplementedError, m.__setitem__,
+                          (slice(0,2,1), slice(0,2,1)), bytearray([1,2]))
+
+        # invalid slice tuple
+        self.assertRaises(TypeError, m.__getitem__, (slice(0,2,1), {}))
+        self.assertRaises(TypeError, m.__setitem__, (slice(0,2,1), {}),
+                          bytearray([1,2]))
+
+        # rvalue is not an exporter
+        self.assertRaises(TypeError, m.__setitem__, slice(0,1,1), [1])
+
+        # non-contiguous slice assignment
+        for flags in (0, ND_PIL):
+            ex1 = ndarray(list(range(12)), shape=[12], strides=[-1], offset=11,
+                          flags=ND_WRITABLE|flags)
+            ex2 = ndarray(list(range(24)), shape=[12], strides=[2], flags=flags)
+            m1 = memoryview(ex1)
+            m2 = memoryview(ex2)
+
+            ex1[2:5] = ex1[2:5]
+            m1[2:5] = m2[2:5]
+
+            self.assertEqual(m1, ex1)
+            self.assertEqual(m2, ex2)
+
+            ex1[1:3][::-1] = ex2[0:2][::1]
+            m1[1:3][::-1] = m2[0:2][::1]
+
+            self.assertEqual(m1, ex1)
+            self.assertEqual(m2, ex2)
+
+            ex1[4:1:-2][::-1] = ex1[1:4:2][::1]
+            m1[4:1:-2][::-1] = m1[1:4:2][::1]
+
+            self.assertEqual(m1, ex1)
+            self.assertEqual(m2, ex2)
+
+    def test_memoryview_array(self):
+
+        def cmptest(testcase, a, b, m, singleitem):
+            for i, _ in enumerate(a):
+                ai = a[i]
+                mi = m[i]
+                testcase.assertEqual(ai, mi)
+                a[i] = singleitem
+                if singleitem != ai:
+                    testcase.assertNotEqual(a, m)
+                    testcase.assertNotEqual(a, b)
+                else:
+                    testcase.assertEqual(a, m)
+                    testcase.assertEqual(a, b)
+                m[i] = singleitem
+                testcase.assertEqual(a, m)
+                testcase.assertEqual(b, m)
+                a[i] = ai
+                m[i] = mi
+
+        for n in range(1, 5):
+            for fmt, items, singleitem in iter_format(n, 'array'):
+                for lslice in genslices(n):
+                    for rslice in genslices(n):
+
+                        a = array.array(fmt, items)
+                        b = array.array(fmt, items)
+                        m = memoryview(b)
+
+                        self.assertEqual(m, a)
+                        self.assertEqual(m.tolist(), a.tolist())
+                        self.assertEqual(m.tobytes(), a.tobytes())
+                        self.assertEqual(len(m), len(a))
+
+                        cmptest(self, a, b, m, singleitem)
+
+                        array_err = None
+                        have_resize = None
+                        try:
+                            al = a[lslice]
+                            ar = a[rslice]
+                            a[lslice] = a[rslice]
+                            have_resize = len(al) != len(ar)
+                        except Exception as e:
+                            array_err = e.__class__
+
+                        m_err = None
+                        try:
+                            m[lslice] = m[rslice]
+                        except Exception as e:
+                            m_err = e.__class__
+
+                        if have_resize: # memoryview cannot change shape
+                            self.assertIs(m_err, ValueError)
+                        elif m_err or array_err:
+                            self.assertIs(m_err, array_err)
+                        else:
+                            self.assertEqual(m, a)
+                            self.assertEqual(m.tolist(), a.tolist())
+                            self.assertEqual(m.tobytes(), a.tobytes())
+                            cmptest(self, a, b, m, singleitem)
+
+    def test_memoryview_compare(self):
+
+        a = array.array('L', [1, 2, 3])
+        b = array.array('L', [1, 2, 7])
+
+        # Ordering comparisons raise:
+        v = memoryview(a)
+        w = memoryview(b)
+        for attr in ('__lt__', '__le__', '__gt__', '__ge__'):
+            self.assertIs(getattr(v, attr)(w), NotImplemented)
+            self.assertIs(getattr(a, attr)(v), NotImplemented)
+
+        # Released views compare equal to themselves:
+        v = memoryview(a)
+        v.release()
+        self.assertEqual(v, v)
+        self.assertNotEqual(v, a)
+        self.assertNotEqual(a, v)
+
+        v = memoryview(a)
+        w = memoryview(a)
+        w.release()
+        self.assertNotEqual(v, w)
+        self.assertNotEqual(w, v)
+
+        # Operand does not implement the buffer protocol:
+        v = memoryview(a)
+        self.assertNotEqual(v, [1, 2, 3])
+
+        # Different formats:
+        c = array.array('l', [1, 2, 3])
+        v = memoryview(a)
+        self.assertNotEqual(v, c)
+        self.assertNotEqual(c, v)
+
+        # Not implemented formats. Ugly, but inevitable. This is the same as
+        # issue #2531: equality is also used for membership testing and must
+        # return a result.
+        a = ndarray([(1, 1.5), (2, 2.7)], shape=[2], format='ld')
+        v = memoryview(a)
+        self.assertNotEqual(v, a)
+        self.assertNotEqual(a, v)
+
+        a = ndarray([b'12345'], shape=[1], format="s")
+        v = memoryview(a)
+        self.assertNotEqual(v, a)
+        self.assertNotEqual(a, v)
+
+        nd = ndarray([(1,1,1), (2,2,2), (3,3,3)], shape=[3], format='iii')
+        v = memoryview(nd)
+        self.assertNotEqual(v, nd)
+        self.assertNotEqual(nd, v)
+
+        # '@' prefix can be dropped:
+        nd1 = ndarray([1,2,3], shape=[3], format='@i')
+        nd2 = ndarray([1,2,3], shape=[3], format='i')
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+        self.assertEqual(v, w)
+        self.assertEqual(w, v)
+        self.assertEqual(v, nd2)
+        self.assertEqual(nd2, v)
+        self.assertEqual(w, nd1)
+        self.assertEqual(nd1, w)
+
+        # ndim = 0
+        nd1 = ndarray(1729, shape=[], format='@L')
+        nd2 = ndarray(1729, shape=[], format='L', flags=ND_WRITABLE)
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+        self.assertEqual(v, w)
+        self.assertEqual(w, v)
+        self.assertEqual(v, nd2)
+        self.assertEqual(nd2, v)
+        self.assertEqual(w, nd1)
+        self.assertEqual(nd1, w)
+
+        self.assertFalse(v.__ne__(w))
+        self.assertFalse(w.__ne__(v))
+
+        w[()] = 1728
+        self.assertNotEqual(v, w)
+        self.assertNotEqual(w, v)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(nd2, v)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(nd1, w)
+
+        self.assertFalse(v.__eq__(w))
+        self.assertFalse(w.__eq__(v))
+
+        nd = ndarray(list(range(12)), shape=[12], flags=ND_WRITABLE|ND_PIL)
+        ex = ndarray(list(range(12)), shape=[12], flags=ND_WRITABLE|ND_PIL)
+        m = memoryview(ex)
+
+        self.assertEqual(m, nd)
+        m[9] = 100
+        self.assertNotEqual(m, nd)
+
+        # ndim = 1: contiguous
+        nd1 = ndarray([-529, 576, -625, 676, -729], shape=[5], format='@h')
+        nd2 = ndarray([-529, 576, -625, 676, 729], shape=[5], format='@h')
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        # ndim = 1: non-contiguous
+        nd1 = ndarray([-529, -625, -729], shape=[3], format='@h')
+        nd2 = ndarray([-529, 576, -625, 676, -729], shape=[5], format='@h')
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd2[::2])
+        self.assertEqual(w[::2], nd1)
+        self.assertEqual(v, w[::2])
+        self.assertEqual(v[::-1], w[::-2])
+
+        # ndim = 1: non-contiguous, suboffsets
+        nd1 = ndarray([-529, -625, -729], shape=[3], format='@h')
+        nd2 = ndarray([-529, 576, -625, 676, -729], shape=[5], format='@h',
+                      flags=ND_PIL)
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd2[::2])
+        self.assertEqual(w[::2], nd1)
+        self.assertEqual(v, w[::2])
+        self.assertEqual(v[::-1], w[::-2])
+
+        # ndim = 1: zeros in shape
+        nd1 = ndarray([900, 961], shape=[0], format='@h')
+        nd2 = ndarray([-900, -961], shape=[0], format='@h')
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertEqual(v, nd2)
+        self.assertEqual(w, nd1)
+        self.assertEqual(v, w)
+
+        # ndim = 1: zero strides
+        nd1 = ndarray([900, 900, 900, 900], shape=[4], format='@L')
+        nd2 = ndarray([900], shape=[4], strides=[0], format='L')
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertEqual(v, nd2)
+        self.assertEqual(w, nd1)
+        self.assertEqual(v, w)
+
+        n = 10
+        for char in fmtdict['@m']:
+            fmt, items, singleitem = randitems(n, 'memoryview', '@', char)
+            for flags in (0, ND_PIL):
+                nd = ndarray(items, shape=[n], format=fmt, flags=flags)
+                m = memoryview(nd)
+                self.assertEqual(m, nd)
+
+                nd = nd[::-3]
+                m = memoryview(nd)
+                self.assertEqual(m, nd)
+
+        ##### ndim > 1: C-contiguous
+        # different values
+        nd1 = ndarray(list(range(-15, 15)), shape=[3, 2, 5], format='@h')
+        nd2 = ndarray(list(range(0, 30)), shape=[3, 2, 5], format='@h')
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        # different shape
+        nd1 = ndarray(list(range(30)), shape=[2, 3, 5], format='L')
+        nd2 = ndarray(list(range(30)), shape=[3, 2, 5], format='L')
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        # different format
+        nd1 = ndarray(list(range(30)), shape=[2, 3, 5], format='L')
+        nd2 = ndarray(list(range(30)), shape=[2, 3, 5], format='l')
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        ##### ndim > 1: Fortran contiguous
+        # different values
+        nd1 = ndarray(list(range(-15, 15)), shape=[5, 2, 3], format='@h',
+                      flags=ND_FORTRAN)
+        nd2 = ndarray(list(range(0, 30)), shape=[5, 2, 3], format='@h',
+                      flags=ND_FORTRAN)
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        # different shape
+        nd1 = ndarray(list(range(-15, 15)), shape=[2, 3, 5], format='l',
+                      flags=ND_FORTRAN)
+        nd2 = ndarray(list(range(-15, 15)), shape=[3, 2, 5], format='l',
+                      flags=ND_FORTRAN)
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        # different format
+        nd1 = ndarray(list(range(30)), shape=[5, 2, 3], format='@h',
+                      flags=ND_FORTRAN)
+        nd2 = ndarray(list(range(30)), shape=[5, 2, 3], format='@b',
+                      flags=ND_FORTRAN)
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        ##### ndim > 1: mixed C/Fortran contiguous
+        lst1 = list(range(-15, 15))
+        lst2 = transpose(lst1, [3, 2, 5])
+        nd1 = ndarray(lst1, shape=[3, 2, 5], format='@l')
+        nd2 = ndarray(lst2, shape=[3, 2, 5], format='l', flags=ND_FORTRAN)
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertEqual(v, w)
+
+        ##### ndim > 1: non-contiguous
+        # different values
+        ex1 = ndarray(list(range(40)), shape=[5, 8], format='@I')
+        nd1 = ex1[3:1:-1, ::-2]
+        ex2 = ndarray(list(range(40)), shape=[5, 8], format='I')
+        nd2 = ex2[1:3:1, ::-2]
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        # different shape
+        ex1 = ndarray(list(range(30)), shape=[2, 3, 5], format='b')
+        nd1 = ex1[1:3:, ::-2]
+        nd2 = ndarray(list(range(30)), shape=[3, 2, 5], format='b')
+        nd2 = ex2[1:3:, ::-2]
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        # different format
+        ex1 = ndarray(list(range(30)), shape=[5, 3, 2], format='i')
+        nd1 = ex1[1:3:, ::-2]
+        nd2 = ndarray(list(range(30)), shape=[5, 3, 2], format='@I')
+        nd2 = ex2[1:3:, ::-2]
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        ##### ndim > 1: zeros in shape
+        nd1 = ndarray(list(range(30)), shape=[0, 3, 2], format='i')
+        nd2 = ndarray(list(range(30)), shape=[5, 0, 2], format='@i')
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        # ndim > 1: zero strides
+        nd1 = ndarray([900]*80, shape=[4, 5, 4], format='@L')
+        nd2 = ndarray([900], shape=[4, 5, 4], strides=[0, 0, 0], format='L')
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertEqual(v, nd2)
+        self.assertEqual(w, nd1)
+        self.assertEqual(v, w)
+        self.assertEqual(v.tolist(), w.tolist())
+
+        ##### ndim > 1: suboffsets
+        ex1 = ndarray(list(range(40)), shape=[5, 8], format='@I')
+        nd1 = ex1[3:1:-1, ::-2]
+        ex2 = ndarray(list(range(40)), shape=[5, 8], format='I', flags=ND_PIL)
+        nd2 = ex2[1:3:1, ::-2]
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        # different shape
+        ex1 = ndarray(list(range(30)), shape=[2, 3, 5], format='b', flags=ND_PIL)
+        nd1 = ex1[1:3:, ::-2]
+        nd2 = ndarray(list(range(30)), shape=[3, 2, 5], format='b')
+        nd2 = ex2[1:3:, ::-2]
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        # different format
+        ex1 = ndarray(list(range(30)), shape=[5, 3, 2], format='i', flags=ND_PIL)
+        nd1 = ex1[1:3:, ::-2]
+        nd2 = ndarray(list(range(30)), shape=[5, 3, 2], format='@I', flags=ND_PIL)
+        nd2 = ex2[1:3:, ::-2]
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertNotEqual(v, nd2)
+        self.assertNotEqual(w, nd1)
+        self.assertNotEqual(v, w)
+
+        # initialize mixed C/Fortran + suboffsets
+        lst1 = list(range(-15, 15))
+        lst2 = transpose(lst1, [3, 2, 5])
+        nd1 = ndarray(lst1, shape=[3, 2, 5], format='@l', flags=ND_PIL)
+        nd2 = ndarray(lst2, shape=[3, 2, 5], format='l', flags=ND_FORTRAN|ND_PIL)
+        v = memoryview(nd1)
+        w = memoryview(nd2)
+
+        self.assertEqual(v, nd1)
+        self.assertEqual(w, nd2)
+        self.assertEqual(v, w)
+
+    def test_memoryview_check_released(self):
+
+        a = array.array('d', [1.1, 2.2, 3.3])
+
+        m = memoryview(a)
+        m.release()
+
+        # PyMemoryView_FromObject()
+        self.assertRaises(ValueError, memoryview, m)
+        # memoryview.cast()
+        self.assertRaises(ValueError, m.cast, 'c')
+        # getbuffer()
+        self.assertRaises(ValueError, ndarray, m)
+        # memoryview.tolist()
+        self.assertRaises(ValueError, m.tolist)
+        # memoryview.tobytes()
+        self.assertRaises(ValueError, m.tobytes)
+        # sequence
+        self.assertRaises(ValueError, eval, "1.0 in m", locals())
+        # subscript
+        self.assertRaises(ValueError, m.__getitem__, 0)
+        # assignment
+        self.assertRaises(ValueError, m.__setitem__, 0, 1)
+
+        for attr in ('obj', 'nbytes', 'readonly', 'itemsize', 'format', 'ndim',
+                     'shape', 'strides', 'suboffsets', 'c_contiguous',
+                     'f_contiguous', 'contiguous'):
+            self.assertRaises(ValueError, m.__getattribute__, attr)
+
+        # richcompare
+        b = array.array('d', [1.1, 2.2, 3.3])
+        m1 = memoryview(a)
+        m2 = memoryview(b)
+
+        self.assertEqual(m1, m2)
+        m1.release()
+        self.assertNotEqual(m1, m2)
+        self.assertNotEqual(m1, a)
+        self.assertEqual(m1, m1)
+
+    def test_memoryview_tobytes(self):
+        # Many implicit tests are already in self.verify().
+
+        nd = ndarray([-529, 576, -625, 676, -729], shape=[5], format='@h')
+
+        m = memoryview(nd)
+        self.assertEqual(m.tobytes(), nd.tobytes())
+
+    def test_memoryview_get_contiguous(self):
+        # Many implicit tests are already in self.verify().
+
+        # no buffer interface
+        self.assertRaises(TypeError, get_contiguous, {}, PyBUF_READ, 'F')
+
+        # writable request to read-only object
+        self.assertRaises(BufferError, get_contiguous, b'x', PyBUF_WRITE, 'C')
+
+        # writable request to non-contiguous object
+        nd = ndarray([1, 2, 3], shape=[2], strides=[2])
+        self.assertRaises(BufferError, get_contiguous, nd, PyBUF_WRITE, 'A')
+
+        # scalar, read-only request from read-only exporter
+        nd = ndarray(9, shape=(), format="L")
+        for order in ['C', 'F', 'A']:
+            m = get_contiguous(nd, PyBUF_READ, order)
+            self.assertEqual(m, nd)
+            self.assertEqual(m[()], 9)
+
+        # scalar, read-only request from writable exporter
+        nd = ndarray(9, shape=(), format="L", flags=ND_WRITABLE)
+        for order in ['C', 'F', 'A']:
+            m = get_contiguous(nd, PyBUF_READ, order)
+            self.assertEqual(m, nd)
+            self.assertEqual(m[()], 9)
+
+        # scalar, writable request
+        for order in ['C', 'F', 'A']:
+            nd[()] = 9
+            m = get_contiguous(nd, PyBUF_WRITE, order)
+            self.assertEqual(m, nd)
+            self.assertEqual(m[()], 9)
+
+            m[()] = 10
+            self.assertEqual(m[()], 10)
+            self.assertEqual(nd[()], 10)
+
+        # zeros in shape
+        nd = ndarray([1], shape=[0], format="L", flags=ND_WRITABLE)
+        for order in ['C', 'F', 'A']:
+            m = get_contiguous(nd, PyBUF_READ, order)
+            self.assertRaises(IndexError, m.__getitem__, 0)
+            self.assertEqual(m, nd)
+            self.assertEqual(m.tolist(), [])
+
+        nd = ndarray(list(range(8)), shape=[2, 0, 7], format="L",
+                     flags=ND_WRITABLE)
+        for order in ['C', 'F', 'A']:
+            m = get_contiguous(nd, PyBUF_READ, order)
+            self.assertEqual(ndarray(m).tolist(), [[], []])
+
+        # one-dimensional
+        nd = ndarray([1], shape=[1], format="h", flags=ND_WRITABLE)
+        for order in ['C', 'F', 'A']:
+            m = get_contiguous(nd, PyBUF_WRITE, order)
+            self.assertEqual(m, nd)
+            self.assertEqual(m.tolist(), nd.tolist())
+
+        nd = ndarray([1, 2, 3], shape=[3], format="b", flags=ND_WRITABLE)
+        for order in ['C', 'F', 'A']:
+            m = get_contiguous(nd, PyBUF_WRITE, order)
+            self.assertEqual(m, nd)
+            self.assertEqual(m.tolist(), nd.tolist())
+
+        # one-dimensional, non-contiguous
+        nd = ndarray([1, 2, 3], shape=[2], strides=[2], flags=ND_WRITABLE)
+        for order in ['C', 'F', 'A']:
+            m = get_contiguous(nd, PyBUF_READ, order)
+            self.assertEqual(m, nd)
+            self.assertEqual(m.tolist(), nd.tolist())
+            self.assertRaises(TypeError, m.__setitem__, 1, 20)
+            self.assertEqual(m[1], 3)
+            self.assertEqual(nd[1], 3)
+
+        nd = nd[::-1]
+        for order in ['C', 'F', 'A']:
+            m = get_contiguous(nd, PyBUF_READ, order)
+            self.assertEqual(m, nd)
+            self.assertEqual(m.tolist(), nd.tolist())
+            self.assertRaises(TypeError, m.__setitem__, 1, 20)
+            self.assertEqual(m[1], 1)
+            self.assertEqual(nd[1], 1)
+
+        # multi-dimensional, contiguous input
+        nd = ndarray(list(range(12)), shape=[3, 4], flags=ND_WRITABLE)
+        for order in ['C', 'A']:
+            m = get_contiguous(nd, PyBUF_WRITE, order)
+            self.assertEqual(ndarray(m).tolist(), nd.tolist())
+
+        self.assertRaises(BufferError, get_contiguous, nd, PyBUF_WRITE, 'F')
+        m = get_contiguous(nd, PyBUF_READ, order)
+        self.assertEqual(ndarray(m).tolist(), nd.tolist())
+
+        nd = ndarray(list(range(12)), shape=[3, 4],
+                     flags=ND_WRITABLE|ND_FORTRAN)
+        for order in ['F', 'A']:
+            m = get_contiguous(nd, PyBUF_WRITE, order)
+            self.assertEqual(ndarray(m).tolist(), nd.tolist())
+
+        self.assertRaises(BufferError, get_contiguous, nd, PyBUF_WRITE, 'C')
+        m = get_contiguous(nd, PyBUF_READ, order)
+        self.assertEqual(ndarray(m).tolist(), nd.tolist())
+
+        # multi-dimensional, non-contiguous input
+        nd = ndarray(list(range(12)), shape=[3, 4], flags=ND_WRITABLE|ND_PIL)
+        for order in ['C', 'F', 'A']:
+            self.assertRaises(BufferError, get_contiguous, nd, PyBUF_WRITE,
+                              order)
+            m = get_contiguous(nd, PyBUF_READ, order)
+            self.assertEqual(ndarray(m).tolist(), nd.tolist())
+
+        # flags
+        nd = ndarray([1,2,3,4,5], shape=[3], strides=[2])
+        m = get_contiguous(nd, PyBUF_READ, 'C')
+        self.assertTrue(m.c_contiguous)
+
+    def test_memoryview_serializing(self):
+
+        # C-contiguous
+        size = struct.calcsize('i')
+        a = array.array('i', [1,2,3,4,5])
+        m = memoryview(a)
+        buf = io.BytesIO(m)
+        b = bytearray(5*size)
+        buf.readinto(b)
+        self.assertEqual(m.tobytes(), b)
+
+        # C-contiguous, multi-dimensional
+        size = struct.calcsize('L')
+        nd = ndarray(list(range(12)), shape=[2,3,2], format="L")
+        m = memoryview(nd)
+        buf = io.BytesIO(m)
+        b = bytearray(2*3*2*size)
+        buf.readinto(b)
+        self.assertEqual(m.tobytes(), b)
+
+        # Fortran contiguous, multi-dimensional
+        #size = struct.calcsize('L')
+        #nd = ndarray(list(range(12)), shape=[2,3,2], format="L",
+        #             flags=ND_FORTRAN)
+        #m = memoryview(nd)
+        #buf = io.BytesIO(m)
+        #b = bytearray(2*3*2*size)
+        #buf.readinto(b)
+        #self.assertEqual(m.tobytes(), b)
+
+    def test_memoryview_hash(self):
+
+        # bytes exporter
+        b = bytes(list(range(12)))
+        m = memoryview(b)
+        self.assertEqual(hash(b), hash(m))
+
+        # C-contiguous
+        mc = m.cast('c', shape=[3,4])
+        self.assertEqual(hash(mc), hash(b))
+
+        # non-contiguous
+        mx = m[::-2]
+        b = bytes(list(range(12))[::-2])
+        self.assertEqual(hash(mx), hash(b))
+
+        # Fortran contiguous
+        nd = ndarray(list(range(30)), shape=[3,2,5], flags=ND_FORTRAN)
+        m = memoryview(nd)
+        self.assertEqual(hash(m), hash(nd))
+
+        # multi-dimensional slice
+        nd = ndarray(list(range(30)), shape=[3,2,5])
+        x = nd[::2, ::, ::-1]
+        m = memoryview(x)
+        self.assertEqual(hash(m), hash(x))
+
+        # multi-dimensional slice with suboffsets
+        nd = ndarray(list(range(30)), shape=[2,5,3], flags=ND_PIL)
+        x = nd[::2, ::, ::-1]
+        m = memoryview(x)
+        self.assertEqual(hash(m), hash(x))
+
+        # non-byte formats
+        nd = ndarray(list(range(12)), shape=[2,2,3], format='L')
+        m = memoryview(nd)
+        self.assertEqual(hash(m), hash(nd.tobytes()))
+
+        nd = ndarray(list(range(-6, 6)), shape=[2,2,3], format='h')
+        m = memoryview(nd)
+        self.assertEqual(hash(m), hash(nd.tobytes()))
+
+    def test_memoryview_release(self):
+
+        # Create re-exporter from getbuffer(memoryview), then release the view.
+        a = bytearray([1,2,3])
+        m = memoryview(a)
+        nd = ndarray(m) # re-exporter
+        self.assertRaises(BufferError, m.release)
+        del nd
+        m.release()
+
+        # chained views
+        a = bytearray([1,2,3])
+        m1 = memoryview(a)
+        m2 = memoryview(m1)
+        nd = ndarray(m2) # re-exporter
+        m1.release()
+        self.assertRaises(BufferError, m2.release)
+        del nd
+        m2.release()
+
+        # Allow changing layout while buffers are exported.
+        nd = ndarray([1,2,3], shape=[3], flags=ND_VAREXPORT)
+        m1 = memoryview(nd)
+
+        nd.push([4,5,6,7,8], shape=[5]) # mutate nd
+        m2 = memoryview(nd)
+
+        x = memoryview(m1)
+        self.assertEqual(x.tolist(), m1.tolist())
+
+        y = memoryview(m2)
+        self.assertEqual(y.tolist(), m2.tolist())
+        self.assertEqual(y.tolist(), nd.tolist())
+        m2.release()
+        y.release()
+
+        nd.pop() # pop the current view
+        self.assertEqual(x.tolist(), nd.tolist())
+
+        del nd
+        m1.release()
+        x.release()
+
+        # If multiple memoryviews share the same managed buffer, implicit
+        # release() in the context manager's __exit__() method should still
+        # work.
+        def catch22(b):
+            with memoryview(b) as m2:
+                pass
+
+        x = bytearray(b'123')
+        with memoryview(x) as m1:
+            catch22(m1)
+            self.assertEqual(m1[0], ord(b'1'))
+
+        # XXX If m1 has exports, raise BufferError.
+        # x = bytearray(b'123')
+        # with memoryview(x) as m1:
+        #     ex = ndarray(m1)
+        #     m1[0] == ord(b'1')
+
+    def test_issue_7385(self):
+        x = ndarray([1,2,3], shape=[3], flags=ND_GETBUF_FAIL)
+        self.assertRaises(BufferError, memoryview, x)
+
+
+def test_main():
+    support.run_unittest(TestBufferProtocol)
+
+
+if __name__ == "__main__":
+    test_main()
diff --git a/Lib/test/test_memoryview.py b/Lib/test/test_memoryview.py
index a5a0ca1b83..8809930acb 100644
--- a/Lib/test/test_memoryview.py
+++ b/Lib/test/test_memoryview.py
@@ -24,15 +24,14 @@ class AbstractMemoryTests:
         return filter(None, [self.ro_type, self.rw_type])
 
     def check_getitem_with_type(self, tp):
-        item = self.getitem_type
         b = tp(self._source)
         oldrefcount = sys.getrefcount(b)
         m = self._view(b)
-        self.assertEqual(m[0], item(b"a"))
-        self.assertIsInstance(m[0], bytes)
-        self.assertEqual(m[5], item(b"f"))
-        self.assertEqual(m[-1], item(b"f"))
-        self.assertEqual(m[-6], item(b"a"))
+        self.assertEqual(m[0], ord(b"a"))
+        self.assertIsInstance(m[0], int)
+        self.assertEqual(m[5], ord(b"f"))
+        self.assertEqual(m[-1], ord(b"f"))
+        self.assertEqual(m[-6], ord(b"a"))
         # Bounds checking
         self.assertRaises(IndexError, lambda: m[6])
         self.assertRaises(IndexError, lambda: m[-7])
@@ -76,7 +75,9 @@ class AbstractMemoryTests:
         b = self.rw_type(self._source)
         oldrefcount = sys.getrefcount(b)
         m = self._view(b)
-        m[0] = tp(b"0")
+        m[0] = ord(b'1')
+        self._check_contents(tp, b, b"1bcdef")
+        m[0:1] = tp(b"0")
         self._check_contents(tp, b, b"0bcdef")
         m[1:3] = tp(b"12")
         self._check_contents(tp, b, b"012def")
@@ -102,10 +103,17 @@ class AbstractMemoryTests:
         # Wrong index/slice types
         self.assertRaises(TypeError, setitem, 0.0, b"a")
         self.assertRaises(TypeError, setitem, (0,), b"a")
+        self.assertRaises(TypeError, setitem, (slice(0,1,1), 0), b"a")
+        self.assertRaises(TypeError, setitem, (0, slice(0,1,1)), b"a")
+        self.assertRaises(TypeError, setitem, (0,), b"a")
         self.assertRaises(TypeError, setitem, "a", b"a")
+        # Not implemented: multidimensional slices
+        slices = (slice(0,1,1), slice(0,1,2))
+        self.assertRaises(NotImplementedError, setitem, slices, b"a")
         # Trying to resize the memory object
-        self.assertRaises(ValueError, setitem, 0, b"")
-        self.assertRaises(ValueError, setitem, 0, b"ab")
+        exc = ValueError if m.format == 'c' else TypeError
+        self.assertRaises(exc, setitem, 0, b"")
+        self.assertRaises(exc, setitem, 0, b"ab")
         self.assertRaises(ValueError, setitem, slice(1,1), b"a")
         self.assertRaises(ValueError, setitem, slice(0,2), b"a")
 
@@ -175,7 +183,7 @@ class AbstractMemoryTests:
         self.assertEqual(m.shape, (6,))
         self.assertEqual(len(m), 6)
         self.assertEqual(m.strides, (self.itemsize,))
-        self.assertEqual(m.suboffsets, None)
+        self.assertEqual(m.suboffsets, ())
         return m
 
     def test_attributes_readonly(self):
@@ -209,12 +217,16 @@ class AbstractMemoryTests:
                 # If tp is a factory rather than a plain type, skip
                 continue
 
+            class MyView():
+                def __init__(self, base):
+                    self.m = memoryview(base)
             class MySource(tp):
                 pass
             class MyObject:
                 pass
 
-            # Create a reference cycle through a memoryview object
+            # Create a reference cycle through a memoryview object.
+            # This exercises mbuf_clear().
             b = MySource(tp(b'abc'))
             m = self._view(b)
             o = MyObject()
@@ -226,6 +238,17 @@ class AbstractMemoryTests:
             gc.collect()
             self.assertTrue(wr() is None, wr())
 
+            # This exercises memory_clear().
+            m = MyView(tp(b'abc'))
+            o = MyObject()
+            m.x = m
+            m.o = o
+            wr = weakref.ref(o)
+            m = o = None
+            # The cycle must be broken
+            gc.collect()
+            self.assertTrue(wr() is None, wr())
+
     def _check_released(self, m, tp):
         check = self.assertRaisesRegex(ValueError, "released")
         with check: bytes(m)
@@ -283,9 +306,12 @@ class AbstractMemoryTests:
         i = io.BytesIO(b'ZZZZ')
         self.assertRaises(TypeError, i.readinto, m)
 
+    def test_getbuf_fail(self):
+        self.assertRaises(TypeError, self._view, {})
+
     def test_hash(self):
         # Memoryviews of readonly (hashable) types are hashable, and they
-        # hash as the corresponding object.
+        # hash as hash(obj.tobytes()).
         tp = self.ro_type
         if tp is None:
             self.skipTest("no read-only type to test")
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index bf22df2269..551c3a5a4a 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -773,8 +773,8 @@ class SizeofTest(unittest.TestCase):
         check(int(PyLong_BASE), size(vh) + 2*self.longdigit)
         check(int(PyLong_BASE**2-1), size(vh) + 2*self.longdigit)
         check(int(PyLong_BASE**2), size(vh) + 3*self.longdigit)
-        # memory (Py_buffer + hash value)
-        check(memoryview(b''), size(h + 'PP2P2i7P' + 'P'))
+        # memoryview
+        check(memoryview(b''), size(h + 'PPiP4P2i5P3cP'))
         # module
         check(unittest, size(h + '3P'))
         # None
diff --git a/Misc/ACKS b/Misc/ACKS
index 2e37b419a1..48ef08061e 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1041,6 +1041,7 @@ John Viega
 Kannan Vijayan
 Kurt Vile
 Norman Vine
+Pauli Virtanen
 Frank Visser
 Johannes Vogel
 Sjoerd de Vries
diff --git a/Misc/NEWS b/Misc/NEWS
index 047f272386..3d5a711305 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,23 @@ What's New in Python 3.3 Alpha 1?
 Core and Builtins
 -----------------
 
+- Issue #10181: New memoryview implementation fixes multiple ownership
+  and lifetime issues of dynamically allocated Py_buffer members (#9990)
+  as well as crashes (#8305, #7433). Many new features have been added
+  (See whatsnew/3.3), and the documentation has been updated extensively.
+  The ndarray test object from _testbuffer.c implements all aspects of
+  PEP-3118, so further development towards the complete implementation
+  of the PEP can proceed in a test-driven manner.
+
+  Thanks to Nick Coghlan, Antoine Pitrou and Pauli Virtanen for review
+  and many ideas.
+
+- Issue #12834: Fix incorrect results of memoryview.tobytes() for
+  non-contiguous arrays.
+
+- Issue #5231: Introduce memoryview.cast() method that allows changing
+  format and shape without making a copy of the underlying memory.
+
 - Issue #14084: Fix a file descriptor leak when importing a module with a
   bad encoding.
 
diff --git a/Misc/valgrind-python.supp b/Misc/valgrind-python.supp
index 194ecbf2b9..20dbf1e7b8 100644
--- a/Misc/valgrind-python.supp
+++ b/Misc/valgrind-python.supp
@@ -412,4 +412,15 @@
    fun:SHA1_Update
 }
 
+{
+   test_buffer_non_debug
+   Memcheck:Addr4
+   fun:PyUnicodeUCS2_FSConverter
+}
+
+{
+   test_buffer_non_debug
+   Memcheck:Addr4
+   fun:PyUnicode_FSConverter
+}
 
diff --git a/Modules/_testbuffer.c b/Modules/_testbuffer.c
new file mode 100644
index 0000000000..39a7bcc9f0
--- /dev/null
+++ b/Modules/_testbuffer.c
@@ -0,0 +1,2683 @@
+/* C Extension module to test all aspects of PEP-3118.
+   Written by Stefan Krah. */
+
+
+#define PY_SSIZE_T_CLEAN
+
+#include "Python.h"
+
+
+/* struct module */
+PyObject *structmodule = NULL;
+PyObject *Struct = NULL;
+PyObject *calcsize = NULL;
+
+/* cache simple format string */
+static const char *simple_fmt = "B";
+PyObject *simple_format = NULL;
+#define SIMPLE_FORMAT(fmt) (fmt == NULL || strcmp(fmt, "B") == 0)
+
+
+/**************************************************************************/
+/*                             NDArray Object                             */
+/**************************************************************************/
+
+static PyTypeObject NDArray_Type;
+#define NDArray_Check(v) (Py_TYPE(v) == &NDArray_Type)
+
+#define CHECK_LIST_OR_TUPLE(v) \
+    if (!PyList_Check(v) && !PyTuple_Check(v)) { \
+        PyErr_SetString(PyExc_TypeError,         \
+            #v " must be a list or a tuple");    \
+        return NULL;                             \
+    }                                            \
+
+#define PyMem_XFree(v) \
+    do { if (v) PyMem_Free(v); } while (0)
+
+/* Maximum number of dimensions. */
+#define ND_MAX_NDIM (2 * PyBUF_MAX_NDIM)
+
+/* Check for the presence of suboffsets in the first dimension. */
+#define HAVE_PTR(suboffsets) (suboffsets && suboffsets[0] >= 0)
+/* Adjust ptr if suboffsets are present. */
+#define ADJUST_PTR(ptr, suboffsets) \
+    (HAVE_PTR(suboffsets) ? *((char**)ptr) + suboffsets[0] : ptr)
+
+/* User configurable flags for the ndarray */
+#define ND_VAREXPORT    0x001   /* change layout while buffers are exported */
+
+/* User configurable flags for each base buffer */
+#define ND_WRITABLE     0x002   /* mark base buffer as writable */
+#define ND_FORTRAN      0x004   /* Fortran contiguous layout */
+#define ND_SCALAR       0x008   /* scalar: ndim = 0 */
+#define ND_PIL          0x010   /* convert to PIL-style array (suboffsets) */
+#define ND_GETBUF_FAIL  0x020   /* test issue 7385 */
+
+/* Default: NumPy style (strides), read-only, no var-export, C-style layout */
+#define ND_DEFAULT      0x0
+
+/* Internal flags for the base buffer */
+#define ND_C            0x040   /* C contiguous layout (default) */
+#define ND_OWN_ARRAYS   0x080   /* consumer owns arrays */
+#define ND_UNUSED       0x100   /* initializer */
+
+/* ndarray properties */
+#define ND_IS_CONSUMER(nd) \
+    (((NDArrayObject *)nd)->head == &((NDArrayObject *)nd)->staticbuf)
+
+/* ndbuf->flags properties */
+#define ND_C_CONTIGUOUS(flags) (!!(flags&(ND_SCALAR|ND_C)))
+#define ND_FORTRAN_CONTIGUOUS(flags) (!!(flags&(ND_SCALAR|ND_FORTRAN)))
+#define ND_ANY_CONTIGUOUS(flags) (!!(flags&(ND_SCALAR|ND_C|ND_FORTRAN)))
+
+/* getbuffer() requests */
+#define REQ_INDIRECT(flags) ((flags&PyBUF_INDIRECT) == PyBUF_INDIRECT)
+#define REQ_C_CONTIGUOUS(flags) ((flags&PyBUF_C_CONTIGUOUS) == PyBUF_C_CONTIGUOUS)
+#define REQ_F_CONTIGUOUS(flags) ((flags&PyBUF_F_CONTIGUOUS) == PyBUF_F_CONTIGUOUS)
+#define REQ_ANY_CONTIGUOUS(flags) ((flags&PyBUF_ANY_CONTIGUOUS) == PyBUF_ANY_CONTIGUOUS)
+#define REQ_STRIDES(flags) ((flags&PyBUF_STRIDES) == PyBUF_STRIDES)
+#define REQ_SHAPE(flags) ((flags&PyBUF_ND) == PyBUF_ND)
+#define REQ_WRITABLE(flags) (flags&PyBUF_WRITABLE)
+#define REQ_FORMAT(flags) (flags&PyBUF_FORMAT)
+
+
+/* Single node of a list of base buffers. The list is needed to implement
+   changes in memory layout while exported buffers are active. */
+static PyTypeObject NDArray_Type;
+
+struct ndbuf;
+typedef struct ndbuf {
+    struct ndbuf *next;
+    struct ndbuf *prev;
+    Py_ssize_t len;     /* length of data */
+    Py_ssize_t offset;  /* start of the array relative to data */
+    char *data;         /* raw data */
+    int flags;          /* capabilities of the base buffer */
+    Py_ssize_t exports; /* number of exports */
+    Py_buffer base;     /* base buffer */
+} ndbuf_t;
+
+typedef struct {
+    PyObject_HEAD
+    int flags;          /* ndarray flags */
+    ndbuf_t staticbuf;  /* static buffer for re-exporting mode */
+    ndbuf_t *head;      /* currently active base buffer */
+} NDArrayObject;
+
+
+static ndbuf_t *
+ndbuf_new(Py_ssize_t nitems, Py_ssize_t itemsize, Py_ssize_t offset, int flags)
+{
+    ndbuf_t *ndbuf;
+    Py_buffer *base;
+    Py_ssize_t len;
+
+    len = nitems * itemsize;
+    if (offset % itemsize) {
+        PyErr_SetString(PyExc_ValueError,
+            "offset must be a multiple of itemsize");
+        return NULL;
+    }
+    if (offset < 0 || offset+itemsize > len) {
+        PyErr_SetString(PyExc_ValueError, "offset out of bounds");
+        return NULL;
+    }
+
+    ndbuf = PyMem_Malloc(sizeof *ndbuf);
+    if (ndbuf == NULL) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+
+    ndbuf->next = NULL;
+    ndbuf->prev = NULL;
+    ndbuf->len = len;
+    ndbuf->offset= offset;
+
+    ndbuf->data = PyMem_Malloc(len);
+    if (ndbuf->data == NULL) {
+        PyErr_NoMemory();
+        PyMem_Free(ndbuf);
+        return NULL;
+    }
+
+    ndbuf->flags = flags;
+    ndbuf->exports = 0;
+
+    base = &ndbuf->base;
+    base->obj = NULL;
+    base->buf = ndbuf->data;
+    base->len = len;
+    base->itemsize = 1;
+    base->readonly = 0;
+    base->format = NULL;
+    base->ndim = 1;
+    base->shape = NULL;
+    base->strides = NULL;
+    base->suboffsets = NULL;
+    base->internal = ndbuf;
+
+    return ndbuf;
+}
+
+static void
+ndbuf_free(ndbuf_t *ndbuf)
+{
+    Py_buffer *base = &ndbuf->base;
+
+    PyMem_XFree(ndbuf->data);
+    PyMem_XFree(base->format);
+    PyMem_XFree(base->shape);
+    PyMem_XFree(base->strides);
+    PyMem_XFree(base->suboffsets);
+
+    PyMem_Free(ndbuf);
+}
+
+static void
+ndbuf_push(NDArrayObject *nd, ndbuf_t *elt)
+{
+    elt->next = nd->head;
+    if (nd->head) nd->head->prev = elt;
+    nd->head = elt;
+    elt->prev = NULL;
+}
+
+static void
+ndbuf_delete(NDArrayObject *nd, ndbuf_t *elt)
+{
+    if (elt->prev)
+        elt->prev->next = elt->next;
+    else
+        nd->head = elt->next;
+    
+    if (elt->next)
+        elt->next->prev = elt->prev;
+
+    ndbuf_free(elt);
+}
+
+static void
+ndbuf_pop(NDArrayObject *nd)
+{
+    ndbuf_delete(nd, nd->head);
+}
+
+
+static PyObject *
+ndarray_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    NDArrayObject *nd;
+
+    nd = PyObject_New(NDArrayObject, &NDArray_Type);
+    if (nd == NULL)
+        return NULL;
+
+    nd->flags = 0;
+    nd->head = NULL;
+    return (PyObject *)nd;
+}
+
+static void
+ndarray_dealloc(NDArrayObject *self)
+{
+    if (self->head) {
+        if (ND_IS_CONSUMER(self)) {
+            Py_buffer *base = &self->head->base;
+            if (self->head->flags & ND_OWN_ARRAYS) {
+                PyMem_XFree(base->shape);
+                PyMem_XFree(base->strides);
+                PyMem_XFree(base->suboffsets);
+            }
+            PyBuffer_Release(base);
+        }
+        else {
+            while (self->head)
+                ndbuf_pop(self);
+        }
+    }
+    PyObject_Del(self);
+}
+
+static int
+ndarray_init_staticbuf(PyObject *exporter, NDArrayObject *nd, int flags)
+{
+    Py_buffer *base = &nd->staticbuf.base;
+
+    if (PyObject_GetBuffer(exporter, base, flags) < 0)
+        return -1;
+
+    nd->head = &nd->staticbuf;
+
+    nd->head->next = NULL;
+    nd->head->prev = NULL;
+    nd->head->len = -1;
+    nd->head->offset = -1;
+    nd->head->data = NULL;
+
+    nd->head->flags = base->readonly ? 0 : ND_WRITABLE;
+    nd->head->exports = 0;
+
+    return 0;
+}
+
+static void
+init_flags(ndbuf_t *ndbuf)
+{
+    if (ndbuf->base.ndim == 0)
+        ndbuf->flags |= ND_SCALAR;
+    if (ndbuf->base.suboffsets)
+        ndbuf->flags |= ND_PIL;
+    if (PyBuffer_IsContiguous(&ndbuf->base, 'C'))
+        ndbuf->flags |= ND_C;
+    if (PyBuffer_IsContiguous(&ndbuf->base, 'F'))
+        ndbuf->flags |= ND_FORTRAN;
+}
+
+
+/****************************************************************************/
+/*                          Buffer/List conversions                         */
+/****************************************************************************/
+
+static Py_ssize_t *strides_from_shape(const ndbuf_t *, int flags);
+
+/* Get number of members in a struct: see issue #12740 */
+typedef struct {
+    PyObject_HEAD
+    Py_ssize_t s_size;
+    Py_ssize_t s_len;
+} PyPartialStructObject;
+
+static Py_ssize_t
+get_nmemb(PyObject *s)
+{
+    return ((PyPartialStructObject *)s)->s_len;
+}
+
+/* Pack all items into the buffer of 'obj'. The 'format' parameter must be
+   in struct module syntax. For standard C types, a single item is an integer.
+   For compound types, a single item is a tuple of integers. */
+static int
+pack_from_list(PyObject *obj, PyObject *items, PyObject *format,
+               Py_ssize_t itemsize)
+{
+    PyObject *structobj, *pack_into;
+    PyObject *args, *offset;
+    PyObject *item, *tmp;
+    Py_ssize_t nitems; /* number of items */
+    Py_ssize_t nmemb;  /* number of members in a single item */
+    Py_ssize_t i, j;
+    int ret = 0;
+
+    assert(PyObject_CheckBuffer(obj));
+    assert(PyList_Check(items) || PyTuple_Check(items));
+
+    structobj = PyObject_CallFunctionObjArgs(Struct, format, NULL);
+    if (structobj == NULL)
+        return -1;
+
+    nitems = PySequence_Fast_GET_SIZE(items);
+    nmemb = get_nmemb(structobj);
+    assert(nmemb >= 1);
+
+    pack_into = PyObject_GetAttrString(structobj, "pack_into");
+    if (pack_into == NULL) {
+        Py_DECREF(structobj);
+        return -1;
+    }
+
+    /* nmemb >= 1 */
+    args = PyTuple_New(2 + nmemb);
+    if (args == NULL) {
+        Py_DECREF(pack_into);
+        Py_DECREF(structobj);
+        return -1;
+    }
+
+    offset = NULL;
+    for (i = 0; i < nitems; i++) {
+        /* Loop invariant: args[j] are borrowed references or NULL. */
+        PyTuple_SET_ITEM(args, 0, obj);
+        for (j = 1; j < 2+nmemb; j++)
+            PyTuple_SET_ITEM(args, j, NULL);
+
+        Py_XDECREF(offset);
+        offset = PyLong_FromSsize_t(i*itemsize);
+        if (offset == NULL) {
+            ret = -1;
+            break;
+        }
+        PyTuple_SET_ITEM(args, 1, offset);
+
+        item = PySequence_Fast_GET_ITEM(items, i);
+        if ((PyBytes_Check(item) || PyLong_Check(item) ||
+             PyFloat_Check(item)) && nmemb == 1) {
+            PyTuple_SET_ITEM(args, 2, item);
+        }
+        else if ((PyList_Check(item) || PyTuple_Check(item)) &&
+                 PySequence_Length(item) == nmemb) {
+            for (j = 0; j < nmemb; j++) {
+                tmp = PySequence_Fast_GET_ITEM(item, j);
+                PyTuple_SET_ITEM(args, 2+j, tmp);
+            }
+        }
+        else {
+            PyErr_SetString(PyExc_ValueError,
+                "mismatch between initializer element and format string");
+            ret = -1;
+            break;
+        }
+
+        tmp = PyObject_CallObject(pack_into, args);
+        if (tmp == NULL) {
+            ret = -1;
+            break;
+        }
+        Py_DECREF(tmp);
+    }
+
+    Py_INCREF(obj); /* args[0] */
+    /* args[1]: offset is either NULL or should be dealloc'd */
+    for (i = 2; i < 2+nmemb; i++) {
+        tmp = PyTuple_GET_ITEM(args, i);
+        Py_XINCREF(tmp);
+    }
+    Py_DECREF(args);
+
+    Py_DECREF(pack_into);
+    Py_DECREF(structobj);
+    return ret;
+
+}
+
+/* Pack single element */
+static int
+pack_single(char *ptr, PyObject *item, const char *fmt, Py_ssize_t itemsize)
+{
+    PyObject *structobj = NULL, *pack_into = NULL, *args = NULL;
+    PyObject *format = NULL, *mview = NULL, *zero = NULL;
+    Py_ssize_t i, nmemb;
+    int ret = -1;
+    PyObject *x;
+
+    if (fmt == NULL) fmt = "B";
+
+    format = PyUnicode_FromString(fmt);
+    if (format == NULL)
+        goto out;
+
+    structobj = PyObject_CallFunctionObjArgs(Struct, format, NULL);
+    if (structobj == NULL)
+        goto out;
+
+    nmemb = get_nmemb(structobj);
+    assert(nmemb >= 1);
+
+    mview = PyMemoryView_FromMemory(ptr, itemsize, PyBUF_WRITE);
+    if (mview == NULL)
+        goto out;
+
+    zero = PyLong_FromLong(0);
+    if (zero == NULL)
+        goto out;
+
+    pack_into = PyObject_GetAttrString(structobj, "pack_into");
+    if (pack_into == NULL)
+        goto out;
+
+    args = PyTuple_New(2+nmemb);
+    if (args == NULL)
+        goto out;
+
+    PyTuple_SET_ITEM(args, 0, mview);
+    PyTuple_SET_ITEM(args, 1, zero);
+
+    if ((PyBytes_Check(item) || PyLong_Check(item) ||
+         PyFloat_Check(item)) && nmemb == 1) {
+         PyTuple_SET_ITEM(args, 2, item);
+    }
+    else if ((PyList_Check(item) || PyTuple_Check(item)) &&
+             PySequence_Length(item) == nmemb) {
+        for (i = 0; i < nmemb; i++) {
+            x = PySequence_Fast_GET_ITEM(item, i);
+            PyTuple_SET_ITEM(args, 2+i, x);
+        }
+    }
+    else {
+        PyErr_SetString(PyExc_ValueError,
+            "mismatch between initializer element and format string");
+        goto args_out;
+    }
+
+    x = PyObject_CallObject(pack_into, args);
+    if (x != NULL) {
+        Py_DECREF(x);
+        ret = 0;
+    }
+
+
+args_out:
+    for (i = 0; i < 2+nmemb; i++)
+        Py_XINCREF(PyTuple_GET_ITEM(args, i));
+    Py_XDECREF(args);
+out:
+    Py_XDECREF(pack_into);
+    Py_XDECREF(zero);
+    Py_XDECREF(mview);
+    Py_XDECREF(structobj);
+    Py_XDECREF(format);
+    return ret;
+}
+
+static void
+copy_rec(const Py_ssize_t *shape, Py_ssize_t ndim, Py_ssize_t itemsize,
+         char *dptr, const Py_ssize_t *dstrides, const Py_ssize_t *dsuboffsets,
+         char *sptr, const Py_ssize_t *sstrides, const Py_ssize_t *ssuboffsets,
+         char *mem)
+{
+    Py_ssize_t i;
+
+    assert(ndim >= 1);
+
+    if (ndim == 1) {
+        if (!HAVE_PTR(dsuboffsets) && !HAVE_PTR(ssuboffsets) &&
+            dstrides[0] == itemsize && sstrides[0] == itemsize) {
+            memmove(dptr, sptr, shape[0] * itemsize);
+        }
+        else {
+            char *p;
+            assert(mem != NULL);
+            for (i=0, p=mem; i<shape[0]; p+=itemsize, sptr+=sstrides[0], i++) {
+                char *xsptr = ADJUST_PTR(sptr, ssuboffsets);
+                memcpy(p, xsptr, itemsize);
+            }
+            for (i=0, p=mem; i<shape[0]; p+=itemsize, dptr+=dstrides[0], i++) {
+                char *xdptr = ADJUST_PTR(dptr, dsuboffsets);
+                memcpy(xdptr, p, itemsize);
+            }
+        }
+        return;
+    }
+
+    for (i = 0; i < shape[0]; dptr+=dstrides[0], sptr+=sstrides[0], i++) {
+        char *xdptr = ADJUST_PTR(dptr, dsuboffsets);
+        char *xsptr = ADJUST_PTR(sptr, ssuboffsets);
+
+        copy_rec(shape+1, ndim-1, itemsize,
+                 xdptr, dstrides+1, dsuboffsets ? dsuboffsets+1 : NULL,
+                 xsptr, sstrides+1, ssuboffsets ? ssuboffsets+1 : NULL,
+                 mem);
+    }
+}
+
+static int
+cmp_structure(Py_buffer *dest, Py_buffer *src)
+{
+    Py_ssize_t i;
+    int same_fmt = ((dest->format == NULL && src->format == NULL) || \
+                    (strcmp(dest->format, src->format) == 0));
+
+    if (!same_fmt ||
+        dest->itemsize != src->itemsize ||
+        dest->ndim != src->ndim)
+        return -1;
+
+    for (i = 0; i < dest->ndim; i++) {
+        if (dest->shape[i] != src->shape[i])
+            return -1;
+        if (dest->shape[i] == 0)
+            break;
+    }
+
+    return 0;
+}
+
+/* Copy src to dest. Both buffers must have the same format, itemsize,
+   ndim and shape. Copying is atomic, the function never fails with
+   a partial copy. */
+static int
+copy_buffer(Py_buffer *dest, Py_buffer *src)
+{
+    char *mem = NULL;
+
+    assert(dest->ndim > 0);
+
+    if (cmp_structure(dest, src) < 0) {
+        PyErr_SetString(PyExc_ValueError,
+            "ndarray assignment: lvalue and rvalue have different structures");
+        return -1;
+    }
+
+    if ((dest->suboffsets && dest->suboffsets[dest->ndim-1] >= 0) ||
+        (src->suboffsets && src->suboffsets[src->ndim-1] >= 0) ||
+        dest->strides[dest->ndim-1] != dest->itemsize ||
+        src->strides[src->ndim-1] != src->itemsize) {
+        mem = PyMem_Malloc(dest->shape[dest->ndim-1] * dest->itemsize);
+        if (mem == NULL) {
+            PyErr_NoMemory();
+            return -1;
+        }
+    }
+
+    copy_rec(dest->shape, dest->ndim, dest->itemsize,
+             dest->buf, dest->strides, dest->suboffsets,
+             src->buf, src->strides, src->suboffsets,
+             mem);
+
+    PyMem_XFree(mem);
+    return 0;
+}
+
+
+/* Unpack single element */
+static PyObject *
+unpack_single(char *ptr, const char *fmt, Py_ssize_t itemsize)
+{
+    PyObject *x, *unpack_from, *mview;
+
+    if (fmt == NULL) {
+        fmt = "B";
+        itemsize = 1;
+    }
+
+    unpack_from = PyObject_GetAttrString(structmodule, "unpack_from");
+    if (unpack_from == NULL)
+        return NULL;
+
+    mview = PyMemoryView_FromMemory(ptr, itemsize, PyBUF_READ);
+    if (mview == NULL) {
+        Py_DECREF(unpack_from);
+        return NULL;
+    }
+
+    x = PyObject_CallFunction(unpack_from, "sO", fmt, mview);
+    Py_DECREF(unpack_from);
+    Py_DECREF(mview);
+    if (x == NULL)
+        return NULL;
+
+    if (PyTuple_GET_SIZE(x) == 1) {
+        PyObject *tmp = PyTuple_GET_ITEM(x, 0);
+        Py_INCREF(tmp);
+        Py_DECREF(x);
+        return tmp;
+    }
+
+    return x;
+}
+
+/* Unpack a multi-dimensional matrix into a nested list. Return a scalar
+   for ndim = 0. */
+static PyObject *
+unpack_rec(PyObject *unpack_from, char *ptr, PyObject *mview, char *item,
+           const Py_ssize_t *shape, const Py_ssize_t *strides,
+           const Py_ssize_t *suboffsets, Py_ssize_t ndim, Py_ssize_t itemsize)
+{
+    PyObject *lst, *x;
+    Py_ssize_t i;
+
+    assert(ndim >= 0);
+    assert(shape != NULL);
+    assert(strides != NULL);
+
+    if (ndim == 0) {
+        memcpy(item, ptr, itemsize);
+        x = PyObject_CallFunctionObjArgs(unpack_from, mview, NULL);
+        if (x == NULL)
+            return NULL;
+        if (PyTuple_GET_SIZE(x) == 1) {
+            PyObject *tmp = PyTuple_GET_ITEM(x, 0);
+            Py_INCREF(tmp);
+            Py_DECREF(x);
+            return tmp;
+        }
+        return x;
+    }
+
+    lst = PyList_New(shape[0]);
+    if (lst == NULL)
+        return NULL;
+
+    for (i = 0; i < shape[0]; ptr+=strides[0], i++) {
+        char *nextptr = ADJUST_PTR(ptr, suboffsets);
+
+        x = unpack_rec(unpack_from, nextptr, mview, item,
+                       shape+1, strides+1, suboffsets ? suboffsets+1 : NULL,
+                       ndim-1, itemsize);
+        if (x == NULL) {
+            Py_DECREF(lst);
+            return NULL;
+        }
+
+        PyList_SET_ITEM(lst, i, x);
+    }
+
+    return lst;
+}
+
+
+static PyObject *
+ndarray_as_list(NDArrayObject *nd)
+{
+    PyObject *structobj = NULL, *unpack_from = NULL;
+    PyObject *lst = NULL, *mview = NULL;
+    Py_buffer *base = &nd->head->base;
+    Py_ssize_t *shape = base->shape;
+    Py_ssize_t *strides = base->strides;
+    Py_ssize_t simple_shape[1];
+    Py_ssize_t simple_strides[1];
+    char *item = NULL;
+    PyObject *format;
+    char *fmt = base->format;
+
+    base = &nd->head->base;
+
+    if (fmt == NULL) {
+        PyErr_SetString(PyExc_ValueError,
+            "ndarray: tolist() does not support format=NULL, use "
+            "tobytes()");
+        return NULL;
+    }
+    if (shape == NULL) {
+        assert(ND_C_CONTIGUOUS(nd->head->flags));
+        assert(base->strides == NULL);
+        assert(base->ndim <= 1);
+        shape = simple_shape;
+        shape[0] = base->len;
+        strides = simple_strides;
+        strides[0] = base->itemsize;
+    }
+    else if (strides == NULL) {
+        assert(ND_C_CONTIGUOUS(nd->head->flags));
+        strides = strides_from_shape(nd->head, 0);
+        if (strides == NULL)
+            return NULL;
+    }
+
+    format = PyUnicode_FromString(fmt);
+    if (format == NULL)
+        goto out;
+
+    structobj = PyObject_CallFunctionObjArgs(Struct, format, NULL);
+    Py_DECREF(format);
+    if (structobj == NULL)
+        goto out;
+
+    unpack_from = PyObject_GetAttrString(structobj, "unpack_from");
+    if (unpack_from == NULL)
+        goto out;
+
+    item = PyMem_Malloc(base->itemsize);
+    if (item == NULL) {
+        PyErr_NoMemory();
+        goto out;
+    }
+
+    mview = PyMemoryView_FromMemory(item, base->itemsize, PyBUF_WRITE);
+    if (mview == NULL)
+        goto out;
+
+    lst = unpack_rec(unpack_from, base->buf, mview, item,
+                     shape, strides, base->suboffsets,
+                     base->ndim, base->itemsize);
+
+out:
+    Py_XDECREF(mview);
+    PyMem_XFree(item);
+    Py_XDECREF(unpack_from);
+    Py_XDECREF(structobj);
+    if (strides != base->strides && strides != simple_strides)
+        PyMem_XFree(strides);
+
+    return lst;
+}
+
+
+/****************************************************************************/
+/*                            Initialize ndbuf                              */
+/****************************************************************************/
+
+/*
+   State of a new ndbuf during initialization. 'OK' means that initialization
+   is complete. 'PTR' means that a pointer has been initialized, but the
+   state of the memory is still undefined and ndbuf->offset is disregarded.
+
+  +-----------------+-----------+-------------+----------------+
+  |                 | ndbuf_new | init_simple | init_structure |
+  +-----------------+-----------+-------------+----------------+
+  | next            | OK (NULL) |     OK      |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | prev            | OK (NULL) |     OK      |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | len             |    OK     |     OK      |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | offset          |    OK     |     OK      |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | data            |    PTR    |     OK      |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | flags           |    user   |    user     |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | exports         |   OK (0)  |     OK      |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | base.obj        | OK (NULL) |     OK      |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | base.buf        |    PTR    |     PTR     |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | base.len        | len(data) |  len(data)  |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | base.itemsize   |     1     |     OK      |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | base.readonly   |     0     |     OK      |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | base.format     |    NULL   |     OK      |       OK       |  
+  +-----------------+-----------+-------------+----------------+
+  | base.ndim       |     1     |      1      |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | base.shape      |    NULL   |    NULL     |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | base.strides    |    NULL   |    NULL     |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | base.suboffsets |    NULL   |    NULL     |       OK       |
+  +-----------------+-----------+-------------+----------------+
+  | base.internal   |    OK     |    OK       |       OK       |
+  +-----------------+-----------+-------------+----------------+
+
+*/
+
+static Py_ssize_t
+get_itemsize(PyObject *format)
+{
+    PyObject *tmp;
+    Py_ssize_t itemsize;
+
+    tmp = PyObject_CallFunctionObjArgs(calcsize, format, NULL);
+    if (tmp == NULL)
+        return -1;
+    itemsize = PyLong_AsSsize_t(tmp);
+    Py_DECREF(tmp);
+
+    return itemsize;
+}
+
+static char *
+get_format(PyObject *format)
+{
+    PyObject *tmp;
+    char *fmt;
+
+    tmp = PyUnicode_AsASCIIString(format);
+    if (tmp == NULL)
+        return NULL;
+    fmt = PyMem_Malloc(PyBytes_GET_SIZE(tmp)+1);
+    if (fmt == NULL) {
+        PyErr_NoMemory();
+        Py_DECREF(tmp);
+        return NULL;
+    }
+    strcpy(fmt, PyBytes_AS_STRING(tmp));
+    Py_DECREF(tmp);
+
+    return fmt;
+}
+
+static int
+init_simple(ndbuf_t *ndbuf, PyObject *items, PyObject *format,
+            Py_ssize_t itemsize)
+{
+    PyObject *mview;
+    Py_buffer *base = &ndbuf->base;
+    int ret;
+
+    mview = PyMemoryView_FromBuffer(base);
+    if (mview == NULL)
+        return -1;
+
+    ret = pack_from_list(mview, items, format, itemsize);
+    Py_DECREF(mview);
+    if (ret < 0)
+        return -1;
+
+    base->readonly = !(ndbuf->flags & ND_WRITABLE);
+    base->itemsize = itemsize;
+    base->format = get_format(format);
+    if (base->format == NULL)
+        return -1;
+
+    return 0;
+}
+
+static Py_ssize_t *
+seq_as_ssize_array(PyObject *seq, Py_ssize_t len, int is_shape)
+{
+    Py_ssize_t *dest;
+    Py_ssize_t x, i;
+
+    dest = PyMem_Malloc(len * (sizeof *dest));
+    if (dest == NULL) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+
+    for (i = 0; i < len; i++) {
+        PyObject *tmp = PySequence_Fast_GET_ITEM(seq, i);
+        if (!PyLong_Check(tmp)) {
+            PyErr_Format(PyExc_ValueError,
+                "elements of %s must be integers",
+                is_shape ? "shape" : "strides");
+            PyMem_Free(dest);
+            return NULL;
+        }
+        x = PyLong_AsSsize_t(tmp);
+        if (PyErr_Occurred()) {
+            PyMem_Free(dest);
+            return NULL;
+        }
+        if (is_shape && x < 0) {
+            PyErr_Format(PyExc_ValueError,
+                "elements of shape must be integers >= 0");
+            PyMem_Free(dest);
+            return NULL;
+        }
+        dest[i] = x;
+    }
+
+    return dest;
+}
+
+static Py_ssize_t *
+strides_from_shape(const ndbuf_t *ndbuf, int flags)
+{
+    const Py_buffer *base = &ndbuf->base;
+    Py_ssize_t *s, i;
+
+    s = PyMem_Malloc(base->ndim * (sizeof *s));
+    if (s == NULL) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+
+    if (flags & ND_FORTRAN) {
+        s[0] = base->itemsize;
+        for (i = 1; i < base->ndim; i++)
+            s[i] = s[i-1] * base->shape[i-1];
+    }
+    else {
+        s[base->ndim-1] = base->itemsize;
+        for (i = base->ndim-2; i >= 0; i--)
+            s[i] = s[i+1] * base->shape[i+1];
+    }
+
+    return s;
+}
+
+/* Bounds check:
+
+     len := complete length of allocated memory
+     offset := start of the array
+
+     A single array element is indexed by:
+
+       i = indices[0] * strides[0] + indices[1] * strides[1] + ...
+
+     imin is reached when all indices[n] combined with positive strides are 0
+     and all indices combined with negative strides are shape[n]-1, which is
+     the maximum index for the nth dimension.
+
+     imax is reached when all indices[n] combined with negative strides are 0
+     and all indices combined with positive strides are shape[n]-1.
+*/
+static int
+verify_structure(Py_ssize_t len, Py_ssize_t itemsize, Py_ssize_t offset,
+                 const Py_ssize_t *shape, const Py_ssize_t *strides,
+                 Py_ssize_t ndim)
+{
+    Py_ssize_t imin, imax;
+    Py_ssize_t n;
+
+    assert(ndim >= 0);
+
+    if (ndim == 0 && (offset < 0 || offset+itemsize > len))
+        goto invalid_combination;
+
+    for (n = 0; n < ndim; n++)
+        if (strides[n] % itemsize) {
+            PyErr_SetString(PyExc_ValueError,
+            "strides must be a multiple of itemsize");
+            return -1;
+        }
+
+    for (n = 0; n < ndim; n++)
+        if (shape[n] == 0)
+            return 0;
+
+    imin = imax = 0;
+    for (n = 0; n < ndim; n++)
+        if (strides[n] <= 0)
+            imin += (shape[n]-1) * strides[n];
+        else
+            imax += (shape[n]-1) * strides[n];
+
+    if (imin + offset < 0 || imax + offset + itemsize > len)
+        goto invalid_combination;
+
+    return 0;
+
+
+invalid_combination:
+    PyErr_SetString(PyExc_ValueError,
+        "invalid combination of buffer, shape and strides");
+    return -1;
+}
+
+/*
+   Convert a NumPy-style array to an array using suboffsets to stride in
+   the first dimension. Requirements: ndim > 0.
+
+   Contiguous example
+   ==================
+
+     Input:
+     ------
+       shape      = {2, 2, 3};
+       strides    = {6, 3, 1};
+       suboffsets = NULL;
+       data       = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
+       buf        = &data[0]
+
+     Output:
+     -------
+       shape      = {2, 2, 3};
+       strides    = {sizeof(char *), 3, 1};
+       suboffsets = {0, -1, -1};
+       data       = {p1, p2, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
+                     |   |   ^                 ^
+                     `---'---'                 |
+                         |                     |
+                         `---------------------'
+       buf        = &data[0]
+
+     So, in the example the input resembles the three-dimensional array
+     char v[2][2][3], while the output resembles an array of two pointers
+     to two-dimensional arrays: char (*v[2])[2][3].
+
+
+   Non-contiguous example:
+   =======================
+
+     Input (with offset and negative strides):
+     -----------------------------------------
+       shape      = {2, 2, 3};
+       strides    = {-6, 3, -1};
+       offset     = 8
+       suboffsets = NULL;
+       data       = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
+
+     Output:
+     -------
+       shape      = {2, 2, 3};
+       strides    = {-sizeof(char *), 3, -1};
+       suboffsets = {2, -1, -1};
+       newdata    = {p1, p2, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
+                     |   |   ^     ^           ^     ^
+                     `---'---'     |           |     `- p2+suboffsets[0]
+                         |         `-----------|--- p1+suboffsets[0]
+                         `---------------------'
+       buf        = &newdata[1]  # striding backwards over the pointers.
+
+     suboffsets[0] is the same as the offset that one would specify if
+     the two {2, 3} subarrays were created directly, hence the name.
+*/
+static int
+init_suboffsets(ndbuf_t *ndbuf)
+{
+    Py_buffer *base = &ndbuf->base;
+    Py_ssize_t start, step;
+    Py_ssize_t imin, suboffset0;
+    Py_ssize_t addsize;
+    Py_ssize_t n;
+    char *data;
+
+    assert(base->ndim > 0);
+    assert(base->suboffsets == NULL);
+
+    /* Allocate new data with additional space for shape[0] pointers. */
+    addsize = base->shape[0] * (sizeof (char *));
+
+    /* Align array start to a multiple of 8. */
+    addsize = 8 * ((addsize + 7) / 8);
+
+    data = PyMem_Malloc(ndbuf->len + addsize);
+    if (data == NULL) {
+        PyErr_NoMemory();
+        return -1;
+    }
+
+    memcpy(data + addsize, ndbuf->data, ndbuf->len);
+
+    PyMem_Free(ndbuf->data);
+    ndbuf->data = data;
+    ndbuf->len += addsize;
+    base->buf = ndbuf->data;
+
+    /* imin: minimum index of the input array relative to ndbuf->offset.
+       suboffset0: offset for each sub-array of the output. This is the
+                   same as calculating -imin' for a sub-array of ndim-1. */
+    imin = suboffset0 = 0;
+    for (n = 0; n < base->ndim; n++) {
+        if (base->shape[n] == 0)
+            break;
+        if (base->strides[n] <= 0) {
+            Py_ssize_t x = (base->shape[n]-1) * base->strides[n];
+            imin += x;
+            suboffset0 += (n >= 1) ? -x : 0;
+        }
+    }
+
+    /* Initialize the array of pointers to the sub-arrays. */
+    start = addsize + ndbuf->offset + imin;
+    step = base->strides[0] < 0 ? -base->strides[0] : base->strides[0];
+
+    for (n = 0; n < base->shape[0]; n++)
+        ((char **)base->buf)[n] = (char *)base->buf + start + n*step;
+
+    /* Initialize suboffsets. */
+    base->suboffsets = PyMem_Malloc(base->ndim * (sizeof *base->suboffsets));
+    if (base->suboffsets == NULL) {
+        PyErr_NoMemory();
+        return -1;
+    }
+    base->suboffsets[0] = suboffset0;
+    for (n = 1; n < base->ndim; n++)
+        base->suboffsets[n] = -1;
+
+    /* Adjust strides for the first (zeroth) dimension. */
+    if (base->strides[0] >= 0) {
+        base->strides[0] = sizeof(char *);
+    }
+    else {
+        /* Striding backwards. */
+        base->strides[0] = -(Py_ssize_t)sizeof(char *);
+        if (base->shape[0] > 0)
+            base->buf = (char *)base->buf + (base->shape[0]-1) * sizeof(char *);
+    }
+
+    ndbuf->flags &= ~(ND_C|ND_FORTRAN);
+    ndbuf->offset = 0;
+    return 0;
+}
+
+static void
+init_len(Py_buffer *base)
+{
+    Py_ssize_t i;
+
+    base->len = 1;
+    for (i = 0; i < base->ndim; i++)
+        base->len *= base->shape[i];
+    base->len *= base->itemsize;
+}
+
+static int
+init_structure(ndbuf_t *ndbuf, PyObject *shape, PyObject *strides,
+               Py_ssize_t ndim)
+{
+    Py_buffer *base = &ndbuf->base;
+
+    base->ndim = (int)ndim;
+    if (ndim == 0) {
+        if (ndbuf->flags & ND_PIL) {
+            PyErr_SetString(PyExc_TypeError,
+                "ndim = 0 cannot be used in conjunction with ND_PIL");
+            return -1;
+        }
+        ndbuf->flags |= (ND_SCALAR|ND_C|ND_FORTRAN);
+        return 0;
+    }
+
+    /* shape */
+    base->shape = seq_as_ssize_array(shape, ndim, 1);
+    if (base->shape == NULL)
+        return -1;
+
+    /* strides */
+    if (strides) {
+        base->strides = seq_as_ssize_array(strides, ndim, 0);
+    }
+    else {
+        base->strides = strides_from_shape(ndbuf, ndbuf->flags);
+    }
+    if (base->strides == NULL)
+        return -1;
+    if (verify_structure(base->len, base->itemsize, ndbuf->offset,
+                         base->shape, base->strides, ndim) < 0)
+        return -1;
+
+    /* buf */
+    base->buf = ndbuf->data + ndbuf->offset;
+
+    /* len */
+    init_len(base);
+
+    /* ndbuf->flags */
+    if (PyBuffer_IsContiguous(base, 'C'))
+        ndbuf->flags |= ND_C;
+    if (PyBuffer_IsContiguous(base, 'F'))
+        ndbuf->flags |= ND_FORTRAN;
+
+
+    /* convert numpy array to suboffset representation */
+    if (ndbuf->flags & ND_PIL) {
+        /* modifies base->buf, base->strides and base->suboffsets **/
+        return init_suboffsets(ndbuf);
+    }
+
+    return 0;
+}
+
+static ndbuf_t *
+init_ndbuf(PyObject *items, PyObject *shape, PyObject *strides,
+           Py_ssize_t offset, PyObject *format, int flags)
+{
+    ndbuf_t *ndbuf;
+    Py_ssize_t ndim;
+    Py_ssize_t nitems;
+    Py_ssize_t itemsize;
+
+    /* ndim = len(shape) */
+    CHECK_LIST_OR_TUPLE(shape)
+    ndim = PySequence_Fast_GET_SIZE(shape);
+    if (ndim > ND_MAX_NDIM) {
+        PyErr_Format(PyExc_ValueError,
+            "ndim must not exceed %d", ND_MAX_NDIM);
+        return NULL;
+    }
+
+    /* len(strides) = len(shape) */
+    if (strides) {
+        CHECK_LIST_OR_TUPLE(strides)
+        if (PySequence_Fast_GET_SIZE(strides) == 0)
+            strides = NULL;
+        else if (flags & ND_FORTRAN) {
+            PyErr_SetString(PyExc_TypeError,
+                "ND_FORTRAN cannot be used together with strides");
+            return NULL;
+        }
+        else if (PySequence_Fast_GET_SIZE(strides) != ndim) {
+            PyErr_SetString(PyExc_ValueError,
+                "len(shape) != len(strides)");
+            return NULL;
+        }
+    }
+
+    /* itemsize */
+    itemsize = get_itemsize(format);
+    if (itemsize <= 0) {
+        if (itemsize == 0) {
+            PyErr_SetString(PyExc_ValueError,
+                "itemsize must not be zero");
+        }
+        return NULL;
+    }
+
+    /* convert scalar to list */
+    if (ndim == 0) {
+        items = Py_BuildValue("(O)", items);
+        if (items == NULL)
+            return NULL;
+    }
+    else {
+        CHECK_LIST_OR_TUPLE(items)
+        Py_INCREF(items);
+    }
+
+    /* number of items */
+    nitems = PySequence_Fast_GET_SIZE(items);
+    if (nitems == 0) {
+        PyErr_SetString(PyExc_ValueError,
+            "initializer list or tuple must not be empty");
+        Py_DECREF(items);
+        return NULL;
+    }
+
+    ndbuf = ndbuf_new(nitems, itemsize, offset, flags);
+    if (ndbuf == NULL) {
+        Py_DECREF(items);
+        return NULL;
+    }
+
+
+    if (init_simple(ndbuf, items, format, itemsize) < 0)
+        goto error;
+    if (init_structure(ndbuf, shape, strides, ndim) < 0)
+        goto error;
+
+    Py_DECREF(items);
+    return ndbuf;
+
+error:
+    Py_DECREF(items);
+    ndbuf_free(ndbuf);
+    return NULL;
+}
+
+/* initialize and push a new base onto the linked list */
+static int
+ndarray_push_base(NDArrayObject *nd, PyObject *items,
+                  PyObject *shape, PyObject *strides,
+                  Py_ssize_t offset, PyObject *format, int flags)
+{
+    ndbuf_t *ndbuf;
+
+    ndbuf = init_ndbuf(items, shape, strides, offset, format, flags);
+    if (ndbuf == NULL)
+        return -1;
+
+    ndbuf_push(nd, ndbuf);
+    return 0;
+}
+
+#define PyBUF_UNUSED 0x10000
+static int
+ndarray_init(PyObject *self, PyObject *args, PyObject *kwds)
+{
+    NDArrayObject *nd = (NDArrayObject *)self;
+    static char *kwlist[] = {
+        "obj", "shape", "strides", "offset", "format", "flags", "getbuf", NULL
+    };
+    PyObject *v = NULL;  /* initializer: scalar, list, tuple or base object */
+    PyObject *shape = NULL;   /* size of each dimension */
+    PyObject *strides = NULL; /* number of bytes to the next elt in each dim */
+    Py_ssize_t offset = 0;            /* buffer offset */
+    PyObject *format = simple_format; /* struct module specifier: "B" */
+    int flags = ND_UNUSED;            /* base buffer and ndarray flags */
+
+    int getbuf = PyBUF_UNUSED; /* re-exporter: getbuffer request flags */
+
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|OOnOii", kwlist,
+            &v, &shape, &strides, &offset, &format, &flags, &getbuf))
+        return -1;
+
+    /* NDArrayObject is re-exporter */
+    if (PyObject_CheckBuffer(v) && shape == NULL) {
+        if (strides || offset || format != simple_format ||
+            flags != ND_UNUSED) {
+            PyErr_SetString(PyExc_TypeError,
+               "construction from exporter object only takes a single "
+               "additional getbuf argument");
+            return -1;
+        }
+
+        getbuf = (getbuf == PyBUF_UNUSED) ? PyBUF_FULL_RO : getbuf;
+
+        if (ndarray_init_staticbuf(v, nd, getbuf) < 0)
+            return -1;
+
+        init_flags(nd->head);
+
+        return 0;
+    }
+
+    /* NDArrayObject is the original base object. */
+    if (getbuf != PyBUF_UNUSED) {
+        PyErr_SetString(PyExc_TypeError,
+            "getbuf argument only valid for construction from exporter "
+            "object");
+        return -1;
+    }
+    if (shape == NULL) {
+        PyErr_SetString(PyExc_TypeError,
+            "shape is a required argument when constructing from "
+            "list, tuple or scalar");
+        return -1;
+    }
+
+    if (flags == ND_UNUSED)
+        flags = ND_DEFAULT;
+    if (flags & ND_VAREXPORT) {
+        nd->flags |= ND_VAREXPORT;
+        flags &= ~ND_VAREXPORT;
+    }
+
+    /* Initialize and push the first base buffer onto the linked list. */
+    return ndarray_push_base(nd, v, shape, strides, offset, format, flags);
+}
+
+/* Push an additional base onto the linked list. */
+static PyObject *
+ndarray_push(PyObject *self, PyObject *args, PyObject *kwds)
+{
+    NDArrayObject *nd = (NDArrayObject *)self;
+    static char *kwlist[] = {
+        "items", "shape", "strides", "offset", "format", "flags", NULL
+    };
+    PyObject *items = NULL;   /* initializer: scalar, list or tuple */
+    PyObject *shape = NULL;   /* size of each dimension */
+    PyObject *strides = NULL; /* number of bytes to the next elt in each dim */
+    PyObject *format = simple_format;  /* struct module specifier: "B" */
+    Py_ssize_t offset = 0;             /* buffer offset */
+    int flags = ND_UNUSED;             /* base buffer flags */
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "OO|OnOi", kwlist,
+            &items, &shape, &strides, &offset, &format, &flags))
+        return NULL;
+
+    if (flags & ND_VAREXPORT) {
+        PyErr_SetString(PyExc_ValueError,
+            "ND_VAREXPORT flag can only be used during object creation");
+        return NULL;
+    }
+    if (ND_IS_CONSUMER(nd)) {
+        PyErr_SetString(PyExc_BufferError,
+            "structure of re-exporting object is immutable");
+        return NULL;
+    }
+    if (!(nd->flags&ND_VAREXPORT) && nd->head->exports > 0) {
+        PyErr_Format(PyExc_BufferError,
+            "cannot change structure: %zd exported buffer%s",
+            nd->head->exports, nd->head->exports==1 ? "" : "s");
+        return NULL;
+    }
+
+    if (ndarray_push_base(nd, items, shape, strides,
+                          offset, format, flags) < 0)
+        return NULL;
+    Py_RETURN_NONE;
+}
+
+/* Pop a base from the linked list (if possible). */
+static PyObject *
+ndarray_pop(PyObject *self, PyObject *dummy)
+{
+    NDArrayObject *nd = (NDArrayObject *)self;
+    if (ND_IS_CONSUMER(nd)) {
+        PyErr_SetString(PyExc_BufferError,
+            "structure of re-exporting object is immutable");
+        return NULL;
+    }
+    if (nd->head->exports > 0) {
+        PyErr_Format(PyExc_BufferError,
+            "cannot change structure: %zd exported buffer%s",
+            nd->head->exports, nd->head->exports==1 ? "" : "s");
+        return NULL;
+    }
+    if (nd->head->next == NULL) {
+        PyErr_SetString(PyExc_BufferError,
+            "list only has a single base");
+        return NULL;
+    }
+
+    ndbuf_pop(nd);
+    Py_RETURN_NONE;
+}
+
+/**************************************************************************/
+/*                               getbuffer                                */
+/**************************************************************************/
+
+static int
+ndarray_getbuf(NDArrayObject *self, Py_buffer *view, int flags)
+{
+    ndbuf_t *ndbuf = self->head;
+    Py_buffer *base = &ndbuf->base;
+    int baseflags = ndbuf->flags;
+
+    /* start with complete information */
+    *view = *base;
+    view->obj = NULL;
+
+    /* reconstruct format */
+    if (view->format == NULL)
+        view->format = "B";
+
+    if (base->ndim != 0 &&
+        ((REQ_SHAPE(flags) && base->shape == NULL) ||
+         (REQ_STRIDES(flags) && base->strides == NULL))) {
+        /* The ndarray is a re-exporter that has been created without full
+           information for testing purposes. In this particular case the
+           ndarray is not a PEP-3118 compliant buffer provider. */
+        PyErr_SetString(PyExc_BufferError,
+            "re-exporter does not provide format, shape or strides");
+        return -1;
+    }
+
+    if (baseflags & ND_GETBUF_FAIL) {
+        PyErr_SetString(PyExc_BufferError,
+            "ND_GETBUF_FAIL: forced test exception");
+        return -1;
+    }
+
+    if (REQ_WRITABLE(flags) && base->readonly) {
+        PyErr_SetString(PyExc_BufferError,
+            "ndarray is not writable");
+        return -1;
+    }
+    if (!REQ_FORMAT(flags)) {
+        /* NULL indicates that the buffer's data type has been cast to 'B'.
+           view->itemsize is the _previous_ itemsize. If shape is present,
+           the equality product(shape) * itemsize = len still holds at this
+           point. The equality calcsize(format) = itemsize does _not_ hold
+           from here on! */
+        view->format = NULL;
+    }
+
+    if (REQ_C_CONTIGUOUS(flags) && !ND_C_CONTIGUOUS(baseflags)) {
+        PyErr_SetString(PyExc_BufferError,
+            "ndarray is not C-contiguous");
+        return -1;
+    }
+    if (REQ_F_CONTIGUOUS(flags) && !ND_FORTRAN_CONTIGUOUS(baseflags)) {
+        PyErr_SetString(PyExc_BufferError,
+            "ndarray is not Fortran contiguous");
+        return -1;
+    }
+    if (REQ_ANY_CONTIGUOUS(flags) && !ND_ANY_CONTIGUOUS(baseflags)) {
+        PyErr_SetString(PyExc_BufferError,
+            "ndarray is not contiguous");
+        return -1;
+    }
+    if (!REQ_INDIRECT(flags) && (baseflags & ND_PIL)) {
+        PyErr_SetString(PyExc_BufferError,
+            "ndarray cannot be represented without suboffsets");
+        return -1;
+    }
+    if (!REQ_STRIDES(flags)) {
+        if (!ND_C_CONTIGUOUS(baseflags)) {
+            PyErr_SetString(PyExc_BufferError,
+                "ndarray is not C-contiguous");
+            return -1;
+        }
+        view->strides = NULL;
+    }
+    if (!REQ_SHAPE(flags)) {
+        /* PyBUF_SIMPLE or PyBUF_WRITABLE: at this point buf is C-contiguous,
+           so base->buf = ndbuf->data. */
+        if (view->format != NULL) {
+            /* PyBUF_SIMPLE|PyBUF_FORMAT and PyBUF_WRITABLE|PyBUF_FORMAT do
+               not make sense. */
+            PyErr_Format(PyExc_BufferError,
+                "ndarray: cannot cast to unsigned bytes if the format flag "
+                "is present");
+            return -1;
+        }
+        /* product(shape) * itemsize = len and calcsize(format) = itemsize
+           do _not_ hold from here on! */
+        view->ndim = 1;
+        view->shape = NULL;
+    }
+
+    view->obj = (PyObject *)self;
+    Py_INCREF(view->obj);
+    self->head->exports++;
+
+    return 0;
+}
+
+static int
+ndarray_releasebuf(NDArrayObject *self, Py_buffer *view)
+{
+    if (!ND_IS_CONSUMER(self)) {
+        ndbuf_t *ndbuf = view->internal;
+        if (--ndbuf->exports == 0 && ndbuf != self->head)
+            ndbuf_delete(self, ndbuf);
+    }
+
+    return 0;
+}
+
+static PyBufferProcs ndarray_as_buffer = {
+    (getbufferproc)ndarray_getbuf,        /* bf_getbuffer */
+    (releasebufferproc)ndarray_releasebuf /* bf_releasebuffer */
+};
+
+
+/**************************************************************************/
+/*                           indexing/slicing                             */
+/**************************************************************************/
+
+static char *
+ptr_from_index(Py_buffer *base, Py_ssize_t index)
+{
+    char *ptr;
+    Py_ssize_t nitems; /* items in the first dimension */
+
+    if (base->shape)
+        nitems = base->shape[0];
+    else {
+        assert(base->ndim == 1 && SIMPLE_FORMAT(base->format));
+        nitems = base->len;
+    }
+
+    if (index < 0) {
+        index += nitems;
+    }
+    if (index < 0 || index >= nitems) {
+        PyErr_SetString(PyExc_IndexError, "index out of bounds");
+        return NULL;
+    }
+
+    ptr = (char *)base->buf;
+
+    if (base->strides == NULL)
+         ptr += base->itemsize * index;
+    else
+         ptr += base->strides[0] * index;
+
+    ptr = ADJUST_PTR(ptr, base->suboffsets);
+
+    return ptr;
+}
+
+static PyObject *
+ndarray_item(NDArrayObject *self, Py_ssize_t index)
+{
+    ndbuf_t *ndbuf = self->head;
+    Py_buffer *base = &ndbuf->base;
+    char *ptr;
+
+    if (base->ndim == 0) {
+        PyErr_SetString(PyExc_TypeError, "invalid indexing of scalar");
+        return NULL;
+    }
+
+    ptr = ptr_from_index(base, index);
+    if (ptr == NULL)
+        return NULL;
+
+    if (base->ndim == 1) {
+        return unpack_single(ptr, base->format, base->itemsize);
+    }
+    else {
+        NDArrayObject *nd;
+        Py_buffer *subview;
+
+        nd = (NDArrayObject *)ndarray_new(&NDArray_Type, NULL, NULL);
+        if (nd == NULL)
+            return NULL;
+
+        if (ndarray_init_staticbuf((PyObject *)self, nd, PyBUF_FULL_RO) < 0) {
+            Py_DECREF(nd);
+            return NULL;
+        }
+
+        subview = &nd->staticbuf.base;
+
+        subview->buf = ptr;
+        subview->len /= subview->shape[0];
+
+        subview->ndim--;
+        subview->shape++;
+        if (subview->strides) subview->strides++;
+        if (subview->suboffsets) subview->suboffsets++;
+
+        init_flags(&nd->staticbuf);
+
+        return (PyObject *)nd;
+    }
+}
+
+/*
+  For each dimension, we get valid (start, stop, step, slicelength) quadruples
+  from PySlice_GetIndicesEx().
+
+  Slicing NumPy arrays
+  ====================
+
+    A pointer to an element in a NumPy array is defined by:
+
+      ptr = (char *)buf + indices[0] * strides[0] +
+                          ... +
+                          indices[ndim-1] * strides[ndim-1]
+
+    Adjust buf:
+    -----------
+      Adding start[n] for each dimension effectively adds the constant:
+
+        c = start[0] * strides[0] + ... + start[ndim-1] * strides[ndim-1]
+
+      Therefore init_slice() adds all start[n] directly to buf.
+
+    Adjust shape:
+    -------------
+      Obviously shape[n] = slicelength[n]
+
+    Adjust strides:
+    ---------------
+      In the original array, the next element in a dimension is reached
+      by adding strides[n] to the pointer. In the sliced array, elements
+      may be skipped, so the next element is reached by adding:
+
+        strides[n] * step[n]
+
+  Slicing PIL arrays
+  ==================
+
+    Layout:
+    -------
+      In the first (zeroth) dimension, PIL arrays have an array of pointers
+      to sub-arrays of ndim-1. Striding in the first dimension is done by
+      getting the index of the nth pointer, dereference it and then add a
+      suboffset to it. The arrays pointed to can best be seen a regular
+      NumPy arrays.
+
+    Adjust buf:
+    -----------
+      In the original array, buf points to a location (usually the start)
+      in the array of pointers. For the sliced array, start[0] can be
+      added to buf in the same manner as for NumPy arrays.
+
+    Adjust suboffsets:
+    ------------------
+      Due to the dereferencing step in the addressing scheme, it is not
+      possible to adjust buf for higher dimensions. Recall that the
+      sub-arrays pointed to are regular NumPy arrays, so for each of
+      those arrays adding start[n] effectively adds the constant:
+
+        c = start[1] * strides[1] + ... + start[ndim-1] * strides[ndim-1]
+
+      This constant is added to suboffsets[0]. suboffsets[0] in turn is
+      added to each pointer right after dereferencing.
+
+    Adjust shape and strides:
+    -------------------------
+      Shape and strides are not influenced by the dereferencing step, so
+      they are adjusted in the same manner as for NumPy arrays.
+
+  Multiple levels of suboffsets
+  =============================
+
+      For a construct like an array of pointers to array of pointers to
+      sub-arrays of ndim-2:
+
+        suboffsets[0] = start[1] * strides[1]
+        suboffsets[1] = start[2] * strides[2] + ...
+*/
+static int
+init_slice(Py_buffer *base, PyObject *key, int dim)
+{
+    Py_ssize_t start, stop, step, slicelength;
+
+    if (PySlice_GetIndicesEx(key, base->shape[dim],
+                             &start, &stop, &step, &slicelength) < 0) {
+        return -1;
+    }
+
+
+    if (base->suboffsets == NULL || dim == 0) {
+    adjust_buf:
+        base->buf = (char *)base->buf + base->strides[dim] * start;
+    }
+    else {
+        Py_ssize_t n = dim-1;
+        while (n >= 0 && base->suboffsets[n] < 0)
+            n--;
+        if (n < 0)
+            goto adjust_buf; /* all suboffsets are negative */
+        base->suboffsets[n] = base->suboffsets[n] + base->strides[dim] * start;
+    }
+    base->shape[dim] = slicelength;
+    base->strides[dim] = base->strides[dim] * step;
+
+    return 0;
+}
+
+static int
+copy_structure(Py_buffer *base)
+{
+    Py_ssize_t *shape = NULL, *strides = NULL, *suboffsets = NULL;
+    Py_ssize_t i;
+
+    shape = PyMem_Malloc(base->ndim * (sizeof *shape));
+    strides = PyMem_Malloc(base->ndim * (sizeof *strides));
+    if (shape == NULL || strides == NULL)
+        goto err_nomem;
+
+    suboffsets = NULL;
+    if (base->suboffsets) {
+        suboffsets = PyMem_Malloc(base->ndim * (sizeof *suboffsets));
+        if (suboffsets == NULL)
+            goto err_nomem;
+    }
+
+    for (i = 0; i < base->ndim; i++) {
+        shape[i] = base->shape[i];
+        strides[i] = base->strides[i];
+        if (suboffsets)
+            suboffsets[i] = base->suboffsets[i];
+    }
+
+    base->shape = shape;
+    base->strides = strides;
+    base->suboffsets = suboffsets;
+
+    return 0;
+
+err_nomem:
+    PyErr_NoMemory();
+    PyMem_XFree(shape);
+    PyMem_XFree(strides);
+    PyMem_XFree(suboffsets);
+    return -1;
+}
+
+static PyObject *
+ndarray_subscript(NDArrayObject *self, PyObject *key)
+{
+    NDArrayObject *nd;
+    ndbuf_t *ndbuf;
+    Py_buffer *base = &self->head->base;
+
+    if (base->ndim == 0) {
+        if (PyTuple_Check(key) && PyTuple_GET_SIZE(key) == 0) {
+            return unpack_single(base->buf, base->format, base->itemsize);
+        }
+        else if (key == Py_Ellipsis) {
+            Py_INCREF(self);
+            return (PyObject *)self;
+        }
+        else {
+            PyErr_SetString(PyExc_TypeError, "invalid indexing of scalar");
+            return NULL;
+        }
+    }
+    if (PyIndex_Check(key)) {
+        Py_ssize_t index = PyLong_AsSsize_t(key);
+        if (index == -1 && PyErr_Occurred())
+            return NULL;
+        return ndarray_item(self, index);
+    }
+
+    nd = (NDArrayObject *)ndarray_new(&NDArray_Type, NULL, NULL);
+    if (nd == NULL)
+        return NULL;
+
+    /* new ndarray is a consumer */
+    if (ndarray_init_staticbuf((PyObject *)self, nd, PyBUF_FULL_RO) < 0) {
+        Py_DECREF(nd);
+        return NULL;
+    }
+
+    /* copy shape, strides and suboffsets */
+    ndbuf = nd->head;
+    base = &ndbuf->base;
+    if (copy_structure(base) < 0) {
+        Py_DECREF(nd);
+        return NULL;
+    }
+    ndbuf->flags |= ND_OWN_ARRAYS;
+
+    if (PySlice_Check(key)) {
+        /* one-dimensional slice */
+        if (init_slice(base, key, 0) < 0)
+            goto err_occurred;
+    }
+    else if PyTuple_Check(key) {
+        /* multi-dimensional slice */
+        PyObject *tuple = key;
+        Py_ssize_t i, n;
+
+        n = PyTuple_GET_SIZE(tuple);
+        for (i = 0; i < n; i++) {
+            key = PyTuple_GET_ITEM(tuple, i);
+            if (!PySlice_Check(key))
+                goto type_error;
+            if (init_slice(base, key, (int)i) < 0)
+                goto err_occurred;
+        }
+    }
+    else {
+        goto type_error;
+    }
+
+    init_len(base);
+    init_flags(ndbuf);
+
+    return (PyObject *)nd;
+
+
+type_error:
+    PyErr_Format(PyExc_TypeError,
+        "cannot index memory using \"%.200s\"",
+        key->ob_type->tp_name);
+err_occurred:
+    Py_DECREF(nd);
+    return NULL;
+}
+
+
+static int
+ndarray_ass_subscript(NDArrayObject *self, PyObject *key, PyObject *value)
+{
+    NDArrayObject *nd;
+    Py_buffer *dest = &self->head->base;
+    Py_buffer src;
+    char *ptr;
+    Py_ssize_t index;
+    int ret = -1;
+
+    if (dest->readonly) {
+        PyErr_SetString(PyExc_TypeError, "ndarray is not writable");
+        return -1;
+    }
+    if (value == NULL) {
+        PyErr_SetString(PyExc_TypeError, "ndarray data cannot be deleted");
+        return -1;
+    }
+    if (dest->ndim == 0) {
+        if (key == Py_Ellipsis ||
+            (PyTuple_Check(key) && PyTuple_GET_SIZE(key) == 0)) {
+            ptr = (char *)dest->buf;
+            return pack_single(ptr, value, dest->format, dest->itemsize);
+        }
+        else {
+            PyErr_SetString(PyExc_TypeError, "invalid indexing of scalar");
+            return -1;
+        }
+    }
+    if (dest->ndim == 1 && PyIndex_Check(key)) {
+        /* rvalue must be a single item */
+        index = PyLong_AsSsize_t(key);
+        if (index == -1 && PyErr_Occurred())
+            return -1;
+        else {
+            ptr = ptr_from_index(dest, index);
+            if (ptr == NULL)
+                return -1;
+        }
+        return pack_single(ptr, value, dest->format, dest->itemsize);
+    }
+
+    /* rvalue must be an exporter */
+    if (PyObject_GetBuffer(value, &src, PyBUF_FULL_RO) == -1)
+        return -1;
+
+    nd = (NDArrayObject *)ndarray_subscript(self, key);
+    if (nd != NULL) {
+        dest = &nd->head->base;
+        ret = copy_buffer(dest, &src);
+        Py_DECREF(nd);
+    }
+
+    PyBuffer_Release(&src);
+    return ret;
+}
+
+static PyObject *
+slice_indices(PyObject *self, PyObject *args)
+{
+    PyObject *ret, *key, *tmp;
+    Py_ssize_t s[4]; /* start, stop, step, slicelength */
+    Py_ssize_t i, len;
+
+    if (!PyArg_ParseTuple(args, "On", &key, &len)) {
+        return NULL;
+    }
+    if (!PySlice_Check(key)) {
+        PyErr_SetString(PyExc_TypeError,
+            "first argument must be a slice object");
+        return NULL;
+    }
+    if (PySlice_GetIndicesEx(key, len, &s[0], &s[1], &s[2], &s[3]) < 0) {
+        return NULL;
+    }
+
+    ret = PyTuple_New(4);
+    if (ret == NULL)
+        return NULL;
+
+    for (i = 0; i < 4; i++) {
+        tmp = PyLong_FromSsize_t(s[i]);
+        if (tmp == NULL)
+            goto error;
+        PyTuple_SET_ITEM(ret, i, tmp);
+    }
+
+    return ret;
+
+error:
+    Py_DECREF(ret);
+    return NULL;
+}
+
+
+static PyMappingMethods ndarray_as_mapping = {
+    NULL,                                 /* mp_length */
+    (binaryfunc)ndarray_subscript,        /* mp_subscript */
+    (objobjargproc)ndarray_ass_subscript  /* mp_ass_subscript */
+};
+
+static PySequenceMethods ndarray_as_sequence = {
+        0,                                /* sq_length */
+        0,                                /* sq_concat */
+        0,                                /* sq_repeat */
+        (ssizeargfunc)ndarray_item,       /* sq_item */
+};
+
+
+/**************************************************************************/
+/*                                 getters                                */
+/**************************************************************************/
+
+static PyObject *
+ssize_array_as_tuple(Py_ssize_t *array, Py_ssize_t len)
+{
+    PyObject *tuple, *x;
+    Py_ssize_t i;
+
+    if (array == NULL)
+        return PyTuple_New(0);
+
+    tuple = PyTuple_New(len);
+    if (tuple == NULL)
+        return NULL;
+
+    for (i = 0; i < len; i++) {
+        x = PyLong_FromSsize_t(array[i]);
+        if (x == NULL) {
+            Py_DECREF(tuple);
+            return NULL;
+        }
+        PyTuple_SET_ITEM(tuple, i, x);
+    }
+
+    return tuple;
+}
+
+static PyObject *
+ndarray_get_flags(NDArrayObject *self, void *closure)
+{
+    return PyLong_FromLong(self->head->flags);
+}
+
+static PyObject *
+ndarray_get_offset(NDArrayObject *self, void *closure)
+{
+    ndbuf_t *ndbuf = self->head;
+    return PyLong_FromSsize_t(ndbuf->offset);
+}
+
+static PyObject *
+ndarray_get_obj(NDArrayObject *self, void *closure)
+{
+    Py_buffer *base = &self->head->base;
+
+    if (base->obj == NULL) { 
+        Py_RETURN_NONE;
+    }
+    Py_INCREF(base->obj);
+    return base->obj;
+}
+
+static PyObject *
+ndarray_get_nbytes(NDArrayObject *self, void *closure)
+{
+    Py_buffer *base = &self->head->base;
+    return PyLong_FromSsize_t(base->len);
+}
+
+static PyObject *
+ndarray_get_readonly(NDArrayObject *self, void *closure)
+{
+    Py_buffer *base = &self->head->base;
+    return PyLong_FromLong(base->readonly);
+}
+
+static PyObject *
+ndarray_get_itemsize(NDArrayObject *self, void *closure)
+{
+    Py_buffer *base = &self->head->base;
+    return PyLong_FromSsize_t(base->itemsize);
+}
+
+static PyObject *
+ndarray_get_format(NDArrayObject *self, void *closure)
+{
+    Py_buffer *base = &self->head->base;
+    char *fmt = base->format ? base->format : "";
+    return PyUnicode_FromString(fmt);
+}
+
+static PyObject *
+ndarray_get_ndim(NDArrayObject *self, void *closure)
+{
+    Py_buffer *base = &self->head->base;
+    return PyLong_FromSsize_t(base->ndim);
+}
+
+static PyObject *
+ndarray_get_shape(NDArrayObject *self, void *closure)
+{
+    Py_buffer *base = &self->head->base;
+    return ssize_array_as_tuple(base->shape, base->ndim);
+}
+
+static PyObject *
+ndarray_get_strides(NDArrayObject *self, void *closure)
+{
+    Py_buffer *base = &self->head->base;
+    return ssize_array_as_tuple(base->strides, base->ndim);
+}
+
+static PyObject *
+ndarray_get_suboffsets(NDArrayObject *self, void *closure)
+{
+    Py_buffer *base = &self->head->base;
+    return ssize_array_as_tuple(base->suboffsets, base->ndim);
+}
+
+static PyObject *
+ndarray_c_contig(PyObject *self, PyObject *dummy)
+{
+    NDArrayObject *nd = (NDArrayObject *)self;
+    int ret = PyBuffer_IsContiguous(&nd->head->base, 'C');
+
+    if (ret != ND_C_CONTIGUOUS(nd->head->flags)) {
+        PyErr_SetString(PyExc_RuntimeError,
+            "results from PyBuffer_IsContiguous() and flags differ");
+        return NULL;
+    }
+    return PyBool_FromLong(ret);
+}
+
+static PyObject *
+ndarray_fortran_contig(PyObject *self, PyObject *dummy)
+{
+    NDArrayObject *nd = (NDArrayObject *)self;
+    int ret = PyBuffer_IsContiguous(&nd->head->base, 'F');
+
+    if (ret != ND_FORTRAN_CONTIGUOUS(nd->head->flags)) {
+        PyErr_SetString(PyExc_RuntimeError,
+            "results from PyBuffer_IsContiguous() and flags differ");
+        return NULL;
+    }
+    return PyBool_FromLong(ret);
+}
+
+static PyObject *
+ndarray_contig(PyObject *self, PyObject *dummy)
+{
+    NDArrayObject *nd = (NDArrayObject *)self;
+    int ret = PyBuffer_IsContiguous(&nd->head->base, 'A');
+
+    if (ret != ND_ANY_CONTIGUOUS(nd->head->flags)) {
+        PyErr_SetString(PyExc_RuntimeError,
+            "results from PyBuffer_IsContiguous() and flags differ");
+        return NULL;
+    }
+    return PyBool_FromLong(ret);
+}
+
+
+static PyGetSetDef ndarray_getset [] =
+{
+  /* ndbuf */
+  { "flags",        (getter)ndarray_get_flags,      NULL, NULL, NULL},
+  { "offset",       (getter)ndarray_get_offset,     NULL, NULL, NULL},
+  /* ndbuf.base */
+  { "obj",          (getter)ndarray_get_obj,        NULL, NULL, NULL},
+  { "nbytes",       (getter)ndarray_get_nbytes,     NULL, NULL, NULL},
+  { "readonly",     (getter)ndarray_get_readonly,   NULL, NULL, NULL},
+  { "itemsize",     (getter)ndarray_get_itemsize,   NULL, NULL, NULL},
+  { "format",       (getter)ndarray_get_format,     NULL, NULL, NULL},
+  { "ndim",         (getter)ndarray_get_ndim,       NULL, NULL, NULL},
+  { "shape",        (getter)ndarray_get_shape,      NULL, NULL, NULL},
+  { "strides",      (getter)ndarray_get_strides,    NULL, NULL, NULL},
+  { "suboffsets",   (getter)ndarray_get_suboffsets, NULL, NULL, NULL},
+  { "c_contiguous", (getter)ndarray_c_contig,       NULL, NULL, NULL},
+  { "f_contiguous", (getter)ndarray_fortran_contig, NULL, NULL, NULL},
+  { "contiguous",   (getter)ndarray_contig,         NULL, NULL, NULL},
+  {NULL}
+};
+
+static PyObject *
+ndarray_tolist(PyObject *self, PyObject *dummy)
+{
+    return ndarray_as_list((NDArrayObject *)self);
+}
+
+static PyObject *
+ndarray_tobytes(PyObject *self, PyObject *dummy)
+{
+    ndbuf_t *ndbuf = ((NDArrayObject *)self)->head;
+    Py_buffer *src = &ndbuf->base;
+    Py_buffer dest;
+    PyObject *ret = NULL;
+    char *mem;
+
+    if (ND_C_CONTIGUOUS(ndbuf->flags))
+        return PyBytes_FromStringAndSize(src->buf, src->len);
+
+    assert(src->shape != NULL);
+    assert(src->strides != NULL);
+    assert(src->ndim > 0);
+
+    mem = PyMem_Malloc(src->len);
+    if (mem == NULL) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+
+    dest = *src;
+    dest.buf = mem;
+    dest.suboffsets = NULL;
+    dest.strides = strides_from_shape(ndbuf, 0);
+    if (dest.strides == NULL)
+        goto out;
+    if (copy_buffer(&dest, src) < 0)
+        goto out;
+
+    ret = PyBytes_FromStringAndSize(mem, src->len);
+
+out:
+    PyMem_XFree(dest.strides);
+    PyMem_Free(mem);
+    return ret;
+}
+
+/* add redundant (negative) suboffsets for testing */
+static PyObject *
+ndarray_add_suboffsets(PyObject *self, PyObject *dummy)
+{
+    NDArrayObject *nd = (NDArrayObject *)self;
+    Py_buffer *base = &nd->head->base;
+    Py_ssize_t i;
+
+    if (base->suboffsets != NULL) {
+        PyErr_SetString(PyExc_TypeError,
+            "cannot add suboffsets to PIL-style array");
+            return NULL;
+    }
+    if (base->strides == NULL) {
+        PyErr_SetString(PyExc_TypeError,
+            "cannot add suboffsets to array without strides");
+            return NULL;
+    }
+
+    base->suboffsets = PyMem_Malloc(base->ndim * (sizeof *base->suboffsets));
+    if (base->suboffsets == NULL) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+
+    for (i = 0; i < base->ndim; i++)
+        base->suboffsets[i] = -1;
+
+    Py_RETURN_NONE;
+}
+
+/* Test PyMemoryView_FromBuffer(): return a memoryview from a static buffer.
+   Obviously this is fragile and only one such view may be active at any
+   time. Never use anything like this in real code! */
+static char *infobuf = NULL;
+static PyObject *
+ndarray_memoryview_from_buffer(PyObject *self, PyObject *dummy)
+{
+    const NDArrayObject *nd = (NDArrayObject *)self;
+    const Py_buffer *view = &nd->head->base;
+    const ndbuf_t *ndbuf;
+    static char format[ND_MAX_NDIM+1];
+    static Py_ssize_t shape[ND_MAX_NDIM];
+    static Py_ssize_t strides[ND_MAX_NDIM];
+    static Py_ssize_t suboffsets[ND_MAX_NDIM];
+    static Py_buffer info;
+    char *p;
+
+    if (!ND_IS_CONSUMER(nd))
+        ndbuf = nd->head; /* self is ndarray/original exporter */
+    else if (NDArray_Check(view->obj) && !ND_IS_CONSUMER(view->obj))
+        /* self is ndarray and consumer from ndarray/original exporter */
+        ndbuf = ((NDArrayObject *)view->obj)->head;
+    else {
+        PyErr_SetString(PyExc_TypeError,
+        "memoryview_from_buffer(): ndarray must be original exporter or "
+        "consumer from ndarray/original exporter");
+         return NULL;
+    }
+
+    info = *view;
+    p = PyMem_Realloc(infobuf, ndbuf->len);
+    if (p == NULL) {
+        PyMem_Free(infobuf);
+        PyErr_NoMemory();
+        infobuf = NULL;
+        return NULL;
+    }
+    else {
+        infobuf = p;
+    }
+    /* copy the complete raw data */
+    memcpy(infobuf, ndbuf->data, ndbuf->len);
+    info.buf = infobuf + ((char *)view->buf - ndbuf->data);
+
+    if (view->format) {
+        if (strlen(view->format) > ND_MAX_NDIM) {
+            PyErr_Format(PyExc_TypeError,
+                "memoryview_from_buffer: format is limited to %d characters",
+                ND_MAX_NDIM);
+                return NULL;
+        }
+        strcpy(format, view->format);
+        info.format = format;
+    }
+    if (view->ndim > ND_MAX_NDIM) {
+        PyErr_Format(PyExc_TypeError,
+            "memoryview_from_buffer: ndim is limited to %d", ND_MAX_NDIM);
+            return NULL;
+    }
+    if (view->shape) {
+        memcpy(shape, view->shape, view->ndim * sizeof(Py_ssize_t));
+        info.shape = shape;
+    }
+    if (view->strides) {
+        memcpy(strides, view->strides, view->ndim * sizeof(Py_ssize_t));
+        info.strides = strides;
+    }
+    if (view->suboffsets) {
+        memcpy(suboffsets, view->suboffsets, view->ndim * sizeof(Py_ssize_t));
+        info.suboffsets = suboffsets;
+    }
+
+    return PyMemoryView_FromBuffer(&info);
+}
+
+/* Get a single item from bufobj at the location specified by seq.
+   seq is a list or tuple of indices. The purpose of this function
+   is to check other functions against PyBuffer_GetPointer(). */
+static PyObject *
+get_pointer(PyObject *self, PyObject *args)
+{
+    PyObject *ret = NULL, *bufobj, *seq;
+    Py_buffer view;
+    Py_ssize_t indices[ND_MAX_NDIM];
+    Py_ssize_t i;
+    void *ptr;
+
+    if (!PyArg_ParseTuple(args, "OO", &bufobj, &seq)) {
+        return NULL;
+    }
+
+    CHECK_LIST_OR_TUPLE(seq);
+    if (PyObject_GetBuffer(bufobj, &view, PyBUF_FULL_RO) < 0)
+        return NULL;
+
+    if (view.ndim > ND_MAX_NDIM) {
+        PyErr_Format(PyExc_ValueError,
+            "get_pointer(): ndim > %d", ND_MAX_NDIM);
+        goto out;
+    }
+    if (PySequence_Fast_GET_SIZE(seq) != view.ndim) {
+        PyErr_SetString(PyExc_ValueError,
+            "get_pointer(): len(indices) != ndim");
+        goto out;
+    }
+
+    for (i = 0; i < view.ndim; i++) {
+        PyObject *x = PySequence_Fast_GET_ITEM(seq, i);
+        indices[i] = PyLong_AsSsize_t(x);
+        if (PyErr_Occurred())
+            goto out;
+        if (indices[i] < 0 || indices[i] >= view.shape[i]) {
+            PyErr_Format(PyExc_ValueError,
+                "get_pointer(): invalid index %zd at position %zd",
+                indices[i], i);
+            goto out;
+        }
+    }
+
+    ptr = PyBuffer_GetPointer(&view, indices);
+    ret = unpack_single(ptr, view.format, view.itemsize);
+
+out:
+    PyBuffer_Release(&view);
+    return ret;
+}
+
+static char
+get_ascii_order(PyObject *order)
+{
+    PyObject *ascii_order;
+    char ord;
+
+    if (!PyUnicode_Check(order)) {
+        PyErr_SetString(PyExc_TypeError,
+            "order must be a string");
+        return CHAR_MAX;
+    }
+
+    ascii_order = PyUnicode_AsASCIIString(order);
+    if (ascii_order == NULL) {
+        return CHAR_MAX;
+    }
+
+    ord = PyBytes_AS_STRING(ascii_order)[0];
+    Py_DECREF(ascii_order);
+    return ord;
+}
+
+/* Get a contiguous memoryview. */
+static PyObject *
+get_contiguous(PyObject *self, PyObject *args)
+{
+    PyObject *obj;
+    PyObject *buffertype;
+    PyObject *order;
+    long type;
+    char ord;
+
+    if (!PyArg_ParseTuple(args, "OOO", &obj, &buffertype, &order)) {
+        return NULL;
+    }
+
+    if (!PyLong_Check(buffertype)) {
+        PyErr_SetString(PyExc_TypeError,
+            "buffertype must be PyBUF_READ or PyBUF_WRITE");
+        return NULL;
+    }
+    type = PyLong_AsLong(buffertype);
+    if (type == -1 && PyErr_Occurred()) {
+        return NULL;
+    }
+
+    ord = get_ascii_order(order);
+    if (ord == CHAR_MAX) {
+        return NULL;
+    }
+
+    return PyMemoryView_GetContiguous(obj, (int)type, ord);
+}
+
+static int
+fmtcmp(const char *fmt1, const char *fmt2)
+{
+    if (fmt1 == NULL) {
+        return fmt2 == NULL || strcmp(fmt2, "B") == 0;
+    }
+    if (fmt2 == NULL) {
+        return fmt1 == NULL || strcmp(fmt1, "B") == 0;
+    }
+    return strcmp(fmt1, fmt2) == 0;
+}
+
+static int
+arraycmp(const Py_ssize_t *a1, const Py_ssize_t *a2, const Py_ssize_t *shape,
+         Py_ssize_t ndim)
+{
+    Py_ssize_t i;
+
+    if (ndim == 1 && shape && shape[0] == 1) {
+        /* This is for comparing strides: For example, the array
+           [175], shape=[1], strides=[-5] is considered contiguous. */
+        return 1;
+    }
+
+    for (i = 0; i < ndim; i++) {
+        if (a1[i] != a2[i]) {
+            return 0;
+        }
+    }
+
+    return 1;
+}
+
+/* Compare two contiguous buffers for physical equality. */
+static PyObject *
+cmp_contig(PyObject *self, PyObject *args)
+{
+    PyObject *b1, *b2; /* buffer objects */
+    Py_buffer v1, v2;
+    PyObject *ret;
+    int equal = 0;
+
+    if (!PyArg_ParseTuple(args, "OO", &b1, &b2)) {
+        return NULL;
+    }
+
+    if (PyObject_GetBuffer(b1, &v1, PyBUF_FULL_RO) < 0) {
+        PyErr_SetString(PyExc_TypeError,
+            "cmp_contig: first argument does not implement the buffer "
+            "protocol");
+        return NULL;
+    }
+    if (PyObject_GetBuffer(b2, &v2, PyBUF_FULL_RO) < 0) {
+        PyErr_SetString(PyExc_TypeError,
+            "cmp_contig: second argument does not implement the buffer "
+            "protocol");
+        PyBuffer_Release(&v1);
+        return NULL;
+    }
+
+    if (!(PyBuffer_IsContiguous(&v1, 'C')&&PyBuffer_IsContiguous(&v2, 'C')) &&
+        !(PyBuffer_IsContiguous(&v1, 'F')&&PyBuffer_IsContiguous(&v2, 'F'))) {
+        goto result;
+    }
+
+    /* readonly may differ if created from non-contiguous */
+    if (v1.len != v2.len ||
+        v1.itemsize != v2.itemsize ||
+        v1.ndim != v2.ndim ||
+        !fmtcmp(v1.format, v2.format) ||
+        !!v1.shape != !!v2.shape ||
+        !!v1.strides != !!v2.strides ||
+        !!v1.suboffsets != !!v2.suboffsets) {
+        goto result;
+    }
+
+    if ((v1.shape && !arraycmp(v1.shape, v2.shape, NULL, v1.ndim)) ||
+        (v1.strides && !arraycmp(v1.strides, v2.strides, v1.shape, v1.ndim)) ||
+        (v1.suboffsets && !arraycmp(v1.suboffsets, v2.suboffsets, NULL,
+                                    v1.ndim))) {
+        goto result;
+    }
+
+    if (memcmp((char *)v1.buf, (char *)v2.buf, v1.len) != 0) {
+        goto result;
+    }
+
+    equal = 1;
+
+result:
+    PyBuffer_Release(&v1);
+    PyBuffer_Release(&v2);
+
+    ret = equal ? Py_True : Py_False; 
+    Py_INCREF(ret);
+    return ret;
+}
+
+static PyObject *
+is_contiguous(PyObject *self, PyObject *args)
+{
+    PyObject *obj;
+    PyObject *order;
+    PyObject *ret = NULL;
+    Py_buffer view;
+    char ord;
+
+    if (!PyArg_ParseTuple(args, "OO", &obj, &order)) {
+        return NULL;
+    }
+
+    if (PyObject_GetBuffer(obj, &view, PyBUF_FULL_RO) < 0) {
+        PyErr_SetString(PyExc_TypeError,
+            "is_contiguous: object does not implement the buffer "
+            "protocol");
+        return NULL;
+    }
+
+    ord = get_ascii_order(order);
+    if (ord == CHAR_MAX) {
+        goto release;
+    }
+
+    ret = PyBuffer_IsContiguous(&view, ord) ? Py_True : Py_False;
+    Py_INCREF(ret);
+
+release:
+    PyBuffer_Release(&view);
+    return ret;
+}
+
+static Py_hash_t
+ndarray_hash(PyObject *self)
+{
+    const NDArrayObject *nd = (NDArrayObject *)self;
+    const Py_buffer *view = &nd->head->base;
+    PyObject *bytes;
+    Py_hash_t hash;
+
+    if (!view->readonly) {
+         PyErr_SetString(PyExc_ValueError,
+             "cannot hash writable ndarray object");
+         return -1;
+    }
+    if (view->obj != NULL && PyObject_Hash(view->obj) == -1) {
+         return -1;
+    }
+
+    bytes = ndarray_tobytes(self, NULL);
+    if (bytes == NULL) {
+        return -1;
+    }
+
+    hash = PyObject_Hash(bytes);
+    Py_DECREF(bytes);
+    return hash;
+}
+
+
+static PyMethodDef ndarray_methods [] =
+{
+    { "tolist", ndarray_tolist, METH_NOARGS, NULL },
+    { "tobytes", ndarray_tobytes, METH_NOARGS, NULL },
+    { "push", (PyCFunction)ndarray_push, METH_VARARGS|METH_KEYWORDS, NULL },
+    { "pop", ndarray_pop, METH_NOARGS, NULL },
+    { "add_suboffsets", ndarray_add_suboffsets, METH_NOARGS, NULL },
+    { "memoryview_from_buffer", ndarray_memoryview_from_buffer, METH_NOARGS, NULL },
+    {NULL}
+};
+
+static PyTypeObject NDArray_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "ndarray",                   /* Name of this type */
+    sizeof(NDArrayObject),       /* Basic object size */
+    0,                           /* Item size for varobject */
+    (destructor)ndarray_dealloc, /* tp_dealloc */
+    0,                           /* tp_print */
+    0,                           /* tp_getattr */
+    0,                           /* tp_setattr */
+    0,                           /* tp_compare */
+    0,                           /* tp_repr */
+    0,                           /* tp_as_number */
+    &ndarray_as_sequence,        /* tp_as_sequence */
+    &ndarray_as_mapping,         /* tp_as_mapping */
+    (hashfunc)ndarray_hash,      /* tp_hash */
+    0,                           /* tp_call */
+    0,                           /* tp_str */
+    PyObject_GenericGetAttr,     /* tp_getattro */
+    0,                           /* tp_setattro */
+    &ndarray_as_buffer,          /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT,          /* tp_flags */
+    0,                           /* tp_doc */
+    0,                           /* tp_traverse */
+    0,                           /* tp_clear */
+    0,                           /* tp_richcompare */
+    0,                           /* tp_weaklistoffset */
+    0,                           /* tp_iter */
+    0,                           /* tp_iternext */
+    ndarray_methods,             /* tp_methods */
+    0,                           /* tp_members */
+    ndarray_getset,              /* tp_getset */
+    0,                           /* tp_base */
+    0,                           /* tp_dict */
+    0,                           /* tp_descr_get */
+    0,                           /* tp_descr_set */
+    0,                           /* tp_dictoffset */
+    ndarray_init,                /* tp_init */
+    0,                           /* tp_alloc */
+    ndarray_new,                 /* tp_new */
+};
+
+
+static struct PyMethodDef _testbuffer_functions[] = {
+    {"slice_indices", slice_indices, METH_VARARGS, NULL},
+    {"get_pointer", get_pointer, METH_VARARGS, NULL},
+    {"get_contiguous", get_contiguous, METH_VARARGS, NULL},
+    {"is_contiguous", is_contiguous, METH_VARARGS, NULL},
+    {"cmp_contig", cmp_contig, METH_VARARGS, NULL},
+    {NULL, NULL}
+};
+
+static struct PyModuleDef _testbuffermodule = {
+    PyModuleDef_HEAD_INIT,
+    "_testbuffer",
+    NULL,
+    -1,
+    _testbuffer_functions,
+    NULL,
+    NULL,
+    NULL,
+    NULL
+};
+
+
+PyMODINIT_FUNC
+PyInit__testbuffer(void)
+{
+    PyObject *m;
+
+    m = PyModule_Create(&_testbuffermodule);
+    if (m == NULL)
+        return NULL;
+
+    Py_TYPE(&NDArray_Type)=&PyType_Type;
+    Py_INCREF(&NDArray_Type);
+    PyModule_AddObject(m, "ndarray", (PyObject *)&NDArray_Type);
+
+    structmodule = PyImport_ImportModule("struct");
+    if (structmodule == NULL)
+        return NULL;
+
+    Struct = PyObject_GetAttrString(structmodule, "Struct");
+    calcsize = PyObject_GetAttrString(structmodule, "calcsize");
+    if (Struct == NULL || calcsize == NULL)
+        return NULL;
+
+    simple_format = PyUnicode_FromString(simple_fmt);
+    if (simple_format == NULL)
+        return NULL;
+
+    PyModule_AddIntConstant(m, "ND_MAX_NDIM", ND_MAX_NDIM);
+    PyModule_AddIntConstant(m, "ND_VAREXPORT", ND_VAREXPORT);
+    PyModule_AddIntConstant(m, "ND_WRITABLE", ND_WRITABLE);
+    PyModule_AddIntConstant(m, "ND_FORTRAN", ND_FORTRAN);
+    PyModule_AddIntConstant(m, "ND_SCALAR", ND_SCALAR);
+    PyModule_AddIntConstant(m, "ND_PIL", ND_PIL);
+    PyModule_AddIntConstant(m, "ND_GETBUF_FAIL", ND_GETBUF_FAIL);
+
+    PyModule_AddIntConstant(m, "PyBUF_SIMPLE", PyBUF_SIMPLE);
+    PyModule_AddIntConstant(m, "PyBUF_WRITABLE", PyBUF_WRITABLE);
+    PyModule_AddIntConstant(m, "PyBUF_FORMAT", PyBUF_FORMAT);
+    PyModule_AddIntConstant(m, "PyBUF_ND", PyBUF_ND);
+    PyModule_AddIntConstant(m, "PyBUF_STRIDES", PyBUF_STRIDES);
+    PyModule_AddIntConstant(m, "PyBUF_INDIRECT", PyBUF_INDIRECT);
+    PyModule_AddIntConstant(m, "PyBUF_C_CONTIGUOUS", PyBUF_C_CONTIGUOUS);
+    PyModule_AddIntConstant(m, "PyBUF_F_CONTIGUOUS", PyBUF_F_CONTIGUOUS);
+    PyModule_AddIntConstant(m, "PyBUF_ANY_CONTIGUOUS", PyBUF_ANY_CONTIGUOUS);
+    PyModule_AddIntConstant(m, "PyBUF_FULL", PyBUF_FULL);
+    PyModule_AddIntConstant(m, "PyBUF_FULL_RO", PyBUF_FULL_RO);
+    PyModule_AddIntConstant(m, "PyBUF_RECORDS", PyBUF_RECORDS);
+    PyModule_AddIntConstant(m, "PyBUF_RECORDS_RO", PyBUF_RECORDS_RO);
+    PyModule_AddIntConstant(m, "PyBUF_STRIDED", PyBUF_STRIDED);
+    PyModule_AddIntConstant(m, "PyBUF_STRIDED_RO", PyBUF_STRIDED_RO);
+    PyModule_AddIntConstant(m, "PyBUF_CONTIG", PyBUF_CONTIG);
+    PyModule_AddIntConstant(m, "PyBUF_CONTIG_RO", PyBUF_CONTIG_RO);
+
+    PyModule_AddIntConstant(m, "PyBUF_READ", PyBUF_READ);
+    PyModule_AddIntConstant(m, "PyBUF_WRITE", PyBUF_WRITE);
+
+    return m;
+}
+
+
+
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index bcb3a0fcbf..23a4d5ac9b 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -275,95 +275,6 @@ test_lazy_hash_inheritance(PyObject* self)
 }
 
 
-/* Issue #7385: Check that memoryview() does not crash
- *   when bf_getbuffer returns an error
- */
-
-static int
-broken_buffer_getbuffer(PyObject *self, Py_buffer *view, int flags)
-{
-    PyErr_SetString(
-        TestError,
-        "test_broken_memoryview: expected error in bf_getbuffer");
-    return -1;
-}
-
-static PyBufferProcs memoryviewtester_as_buffer = {
-    (getbufferproc)broken_buffer_getbuffer,     /* bf_getbuffer */
-    0,          /* bf_releasebuffer */
-};
-
-static PyTypeObject _MemoryViewTester_Type = {
-    PyVarObject_HEAD_INIT(NULL, 0)
-    "memoryviewtester",         /* Name of this type */
-    sizeof(PyObject),           /* Basic object size */
-    0,                          /* Item size for varobject */
-    (destructor)PyObject_Del, /* tp_dealloc */
-    0,                          /* tp_print */
-    0,                          /* tp_getattr */
-    0,                          /* tp_setattr */
-    0,                          /* tp_compare */
-    0,                          /* tp_repr */
-    0,                          /* tp_as_number */
-    0,                          /* tp_as_sequence */
-    0,                          /* tp_as_mapping */
-    0,                          /* tp_hash */
-    0,                          /* tp_call */
-    0,                          /* tp_str */
-    PyObject_GenericGetAttr,  /* tp_getattro */
-    0,                          /* tp_setattro */
-    &memoryviewtester_as_buffer,                        /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT,         /* tp_flags */
-    0,                          /* tp_doc */
-    0,                          /* tp_traverse */
-    0,                          /* tp_clear */
-    0,                          /* tp_richcompare */
-    0,                          /* tp_weaklistoffset */
-    0,                          /* tp_iter */
-    0,                          /* tp_iternext */
-    0,                          /* tp_methods */
-    0,                          /* tp_members */
-    0,                          /* tp_getset */
-    0,                          /* tp_base */
-    0,                          /* tp_dict */
-    0,                          /* tp_descr_get */
-    0,                          /* tp_descr_set */
-    0,                          /* tp_dictoffset */
-    0,                          /* tp_init */
-    0,                          /* tp_alloc */
-    PyType_GenericNew,                  /* tp_new */
-};
-
-static PyObject*
-test_broken_memoryview(PyObject* self)
-{
-    PyObject *obj = PyObject_New(PyObject, &_MemoryViewTester_Type);
-    PyObject *res;
-
-    if (obj == NULL) {
-        PyErr_Clear();
-        PyErr_SetString(
-            TestError,
-            "test_broken_memoryview: failed to create object");
-        return NULL;
-    }
-
-    res = PyMemoryView_FromObject(obj);
-    if (res || !PyErr_Occurred()){
-        PyErr_SetString(
-            TestError,
-            "test_broken_memoryview: memoryview() didn't raise an Exception");
-        Py_XDECREF(res);
-        Py_DECREF(obj);
-        return NULL;
-    }
-
-    PyErr_Clear();
-    Py_DECREF(obj);
-    Py_RETURN_NONE;
-}
-
-
 /* Tests of PyLong_{As, From}{Unsigned,}Long(), and (#ifdef HAVE_LONG_LONG)
    PyLong_{As, From}{Unsigned,}LongLong().
 
@@ -2421,7 +2332,6 @@ static PyMethodDef TestMethods[] = {
     {"test_list_api",           (PyCFunction)test_list_api,      METH_NOARGS},
     {"test_dict_iteration",     (PyCFunction)test_dict_iteration,METH_NOARGS},
     {"test_lazy_hash_inheritance",      (PyCFunction)test_lazy_hash_inheritance,METH_NOARGS},
-    {"test_broken_memoryview",          (PyCFunction)test_broken_memoryview,METH_NOARGS},
     {"test_long_api",           (PyCFunction)test_long_api,      METH_NOARGS},
     {"test_long_and_overflow", (PyCFunction)test_long_and_overflow,
      METH_NOARGS},
@@ -2684,7 +2594,6 @@ PyInit__testcapi(void)
         return NULL;
 
     Py_TYPE(&_HashInheritanceTester_Type)=&PyType_Type;
-    Py_TYPE(&_MemoryViewTester_Type)=&PyType_Type;
 
     Py_TYPE(&test_structmembersType)=&PyType_Type;
     Py_INCREF(&test_structmembersType);
diff --git a/Objects/abstract.c b/Objects/abstract.c
index 47010d60e5..62fccdcce6 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -340,7 +340,7 @@ PyObject_GetBuffer(PyObject *obj, Py_buffer *view, int flags)
 }
 
 static int
-_IsFortranContiguous(Py_buffer *view)
+_IsFortranContiguous(const Py_buffer *view)
 {
     Py_ssize_t sd, dim;
     int i;
@@ -361,7 +361,7 @@ _IsFortranContiguous(Py_buffer *view)
 }
 
 static int
-_IsCContiguous(Py_buffer *view)
+_IsCContiguous(const Py_buffer *view)
 {
     Py_ssize_t sd, dim;
     int i;
@@ -382,16 +382,16 @@ _IsCContiguous(Py_buffer *view)
 }
 
 int
-PyBuffer_IsContiguous(Py_buffer *view, char fort)
+PyBuffer_IsContiguous(const Py_buffer *view, char order)
 {
 
     if (view->suboffsets != NULL) return 0;
 
-    if (fort == 'C')
+    if (order == 'C')
         return _IsCContiguous(view);
-    else if (fort == 'F')
+    else if (order == 'F')
         return _IsFortranContiguous(view);
-    else if (fort == 'A')
+    else if (order == 'A')
         return (_IsCContiguous(view) || _IsFortranContiguous(view));
     return 0;
 }
@@ -651,7 +651,7 @@ int
 PyBuffer_FillInfo(Py_buffer *view, PyObject *obj, void *buf, Py_ssize_t len,
               int readonly, int flags)
 {
-    if (view == NULL) return 0;
+    if (view == NULL) return 0; /* XXX why not -1? */
     if (((flags & PyBUF_WRITABLE) == PyBUF_WRITABLE) &&
         (readonly == 1)) {
         PyErr_SetString(PyExc_BufferError,
diff --git a/Objects/memoryobject.c b/Objects/memoryobject.c
index 295a742d6d..e87abf5497 100644
--- a/Objects/memoryobject.c
+++ b/Objects/memoryobject.c
@@ -1,127 +1,918 @@
-
 /* Memoryview object implementation */
 
 #include "Python.h"
+#include <stddef.h>
+
+
+/****************************************************************************/
+/*                           ManagedBuffer Object                           */
+/****************************************************************************/
+
+/*
+   ManagedBuffer Object:
+   ---------------------
+
+     The purpose of this object is to facilitate the handling of chained
+     memoryviews that have the same underlying exporting object. PEP-3118
+     allows the underlying object to change while a view is exported. This
+     could lead to unexpected results when constructing a new memoryview
+     from an existing memoryview.
+
+     Rather than repeatedly redirecting buffer requests to the original base
+     object, all chained memoryviews use a single buffer snapshot. This
+     snapshot is generated by the constructor _PyManagedBuffer_FromObject().
+
+   Ownership rules:
+   ----------------
+
+     The master buffer inside a managed buffer is filled in by the original
+     base object. shape, strides, suboffsets and format are read-only for
+     all consumers.
+
+     A memoryview's buffer is a private copy of the exporter's buffer. shape,
+     strides and suboffsets belong to the memoryview and are thus writable.
+
+     If a memoryview itself exports several buffers via memory_getbuf(), all
+     buffer copies share shape, strides and suboffsets. In this case, the
+     arrays are NOT writable.
+
+   Reference count assumptions:
+   ----------------------------
+
+     The 'obj' member of a Py_buffer must either be NULL or refer to the
+     exporting base object. In the Python codebase, all getbufferprocs
+     return a new reference to view.obj (example: bytes_buffer_getbuffer()).
+
+     PyBuffer_Release() decrements view.obj (if non-NULL), so the
+     releasebufferprocs must NOT decrement view.obj.
+*/
+
 
-#define IS_RELEASED(memobj) \
-    (((PyMemoryViewObject *) memobj)->view.buf == NULL)
+#define XSTRINGIZE(v) #v
+#define STRINGIZE(v) XSTRINGIZE(v)
 
-#define CHECK_RELEASED(memobj) \
-    if (IS_RELEASED(memobj)) { \
-        PyErr_SetString(PyExc_ValueError, \
-                        "operation forbidden on released memoryview object"); \
-        return NULL; \
+#define CHECK_MBUF_RELEASED(mbuf) \
+    if (((_PyManagedBufferObject *)mbuf)->flags&_Py_MANAGED_BUFFER_RELEASED) { \
+        PyErr_SetString(PyExc_ValueError,                                      \
+            "operation forbidden on released memoryview object");              \
+        return NULL;                                                           \
     }
 
-#define CHECK_RELEASED_INT(memobj) \
-    if (IS_RELEASED(memobj)) { \
-        PyErr_SetString(PyExc_ValueError, \
-                        "operation forbidden on released memoryview object"); \
-        return -1; \
+
+Py_LOCAL_INLINE(_PyManagedBufferObject *)
+mbuf_alloc(void)
+{
+    _PyManagedBufferObject *mbuf;
+
+    mbuf = (_PyManagedBufferObject *)
+        PyObject_GC_New(_PyManagedBufferObject, &_PyManagedBuffer_Type);
+    if (mbuf == NULL)
+        return NULL;
+    mbuf->flags = 0;
+    mbuf->exports = 0;
+    mbuf->master.obj = NULL;
+    _PyObject_GC_TRACK(mbuf);
+
+    return mbuf;
+}
+
+static PyObject *
+_PyManagedBuffer_FromObject(PyObject *base)
+{
+    _PyManagedBufferObject *mbuf;
+
+    mbuf = mbuf_alloc();
+    if (mbuf == NULL)
+        return NULL;
+
+    if (PyObject_GetBuffer(base, &mbuf->master, PyBUF_FULL_RO) < 0) {
+        /* mbuf->master.obj must be NULL. */
+        Py_DECREF(mbuf);
+        return NULL;
     }
 
-static Py_ssize_t
-get_shape0(Py_buffer *buf)
-{
-    if (buf->shape != NULL)
-        return buf->shape[0];
-    if (buf->ndim == 0)
-        return 1;
-    PyErr_SetString(PyExc_TypeError,
-        "exported buffer does not have any shape information associated "
-        "to it");
-    return -1;
+    /* Assume that master.obj is a new reference to base. */
+    assert(mbuf->master.obj == base);
+
+    return (PyObject *)mbuf;
 }
 
 static void
-dup_buffer(Py_buffer *dest, Py_buffer *src)
+mbuf_release(_PyManagedBufferObject *self)
 {
-    *dest = *src;
-    if (src->ndim == 1 && src->shape != NULL) {
-        dest->shape = &(dest->smalltable[0]);
-        dest->shape[0] = get_shape0(src);
-    }
-    if (src->ndim == 1 && src->strides != NULL) {
-        dest->strides = &(dest->smalltable[1]);
-        dest->strides[0] = src->strides[0];
-    }
+    if (self->flags&_Py_MANAGED_BUFFER_RELEASED)
+        return;
+
+    /* NOTE: at this point self->exports can still be > 0 if this function
+       is called from mbuf_clear() to break up a reference cycle. */
+    self->flags |= _Py_MANAGED_BUFFER_RELEASED;
+
+    /* PyBuffer_Release() decrements master->obj and sets it to NULL. */
+    _PyObject_GC_UNTRACK(self);
+    PyBuffer_Release(&self->master);
+}
+
+static void
+mbuf_dealloc(_PyManagedBufferObject *self)
+{
+    assert(self->exports == 0);
+    mbuf_release(self);
+    if (self->flags&_Py_MANAGED_BUFFER_FREE_FORMAT)
+        PyMem_Free(self->master.format);
+    PyObject_GC_Del(self);
 }
 
 static int
-memory_getbuf(PyMemoryViewObject *self, Py_buffer *view, int flags)
+mbuf_traverse(_PyManagedBufferObject *self, visitproc visit, void *arg)
 {
-    int res = 0;
-    CHECK_RELEASED_INT(self);
-    if (self->view.obj != NULL)
-        res = PyObject_GetBuffer(self->view.obj, view, flags);
-    if (view)
-        dup_buffer(view, &self->view);
-    return res;
+    Py_VISIT(self->master.obj);
+    return 0;
 }
 
-static void
-memory_releasebuf(PyMemoryViewObject *self, Py_buffer *view)
+static int
+mbuf_clear(_PyManagedBufferObject *self)
 {
-    PyBuffer_Release(view);
+    assert(self->exports >= 0);
+    mbuf_release(self);
+    return 0;
 }
 
+PyTypeObject _PyManagedBuffer_Type = {
+    PyVarObject_HEAD_INIT(&PyType_Type, 0)
+    "managedbuffer",
+    sizeof(_PyManagedBufferObject),
+    0,
+    (destructor)mbuf_dealloc,                /* tp_dealloc */
+    0,                                       /* tp_print */
+    0,                                       /* tp_getattr */
+    0,                                       /* tp_setattr */
+    0,                                       /* tp_reserved */
+    0,                                       /* tp_repr */
+    0,                                       /* tp_as_number */
+    0,                                       /* tp_as_sequence */
+    0,                                       /* tp_as_mapping */
+    0,                                       /* tp_hash */
+    0,                                       /* tp_call */
+    0,                                       /* tp_str */
+    PyObject_GenericGetAttr,                 /* tp_getattro */
+    0,                                       /* tp_setattro */
+    0,                                       /* tp_as_buffer */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
+    0,                                       /* tp_doc */
+    (traverseproc)mbuf_traverse,             /* tp_traverse */
+    (inquiry)mbuf_clear                      /* tp_clear */
+};
+
+
+/****************************************************************************/
+/*                             MemoryView Object                            */
+/****************************************************************************/
+
+/* In the process of breaking reference cycles mbuf_release() can be
+   called before memory_release(). */
+#define BASE_INACCESSIBLE(mv) \
+    (((PyMemoryViewObject *)mv)->flags&_Py_MEMORYVIEW_RELEASED || \
+     ((PyMemoryViewObject *)mv)->mbuf->flags&_Py_MANAGED_BUFFER_RELEASED)
+
+#define CHECK_RELEASED(mv) \
+    if (BASE_INACCESSIBLE(mv)) {                                  \
+        PyErr_SetString(PyExc_ValueError,                         \
+            "operation forbidden on released memoryview object"); \
+        return NULL;                                              \
+    }
+
+#define CHECK_RELEASED_INT(mv) \
+    if (BASE_INACCESSIBLE(mv)) {                                  \
+        PyErr_SetString(PyExc_ValueError,                         \
+            "operation forbidden on released memoryview object"); \
+        return -1;                                                \
+    }
+
+#define CHECK_LIST_OR_TUPLE(v) \
+    if (!PyList_Check(v) && !PyTuple_Check(v)) { \
+        PyErr_SetString(PyExc_TypeError,         \
+            #v " must be a list or a tuple");    \
+        return NULL;                             \
+    }
+
+#define VIEW_ADDR(mv) (&((PyMemoryViewObject *)mv)->view)
+
+/* Check for the presence of suboffsets in the first dimension. */
+#define HAVE_PTR(suboffsets) (suboffsets && suboffsets[0] >= 0)
+/* Adjust ptr if suboffsets are present. */
+#define ADJUST_PTR(ptr, suboffsets) \
+    (HAVE_PTR(suboffsets) ? *((char**)ptr) + suboffsets[0] : ptr)
+
+/* Memoryview buffer properties */
+#define MV_C_CONTIGUOUS(flags) (flags&(_Py_MEMORYVIEW_SCALAR|_Py_MEMORYVIEW_C))
+#define MV_F_CONTIGUOUS(flags) \
+    (flags&(_Py_MEMORYVIEW_SCALAR|_Py_MEMORYVIEW_FORTRAN))
+#define MV_ANY_CONTIGUOUS(flags) \
+    (flags&(_Py_MEMORYVIEW_SCALAR|_Py_MEMORYVIEW_C|_Py_MEMORYVIEW_FORTRAN))
+
+/* Fast contiguity test. Caller must ensure suboffsets==NULL and ndim==1. */
+#define MV_CONTIGUOUS_NDIM1(view) \
+    ((view)->shape[0] == 1 || (view)->strides[0] == (view)->itemsize)
+
+/* getbuffer() requests */
+#define REQ_INDIRECT(flags) ((flags&PyBUF_INDIRECT) == PyBUF_INDIRECT)
+#define REQ_C_CONTIGUOUS(flags) ((flags&PyBUF_C_CONTIGUOUS) == PyBUF_C_CONTIGUOUS)
+#define REQ_F_CONTIGUOUS(flags) ((flags&PyBUF_F_CONTIGUOUS) == PyBUF_F_CONTIGUOUS)
+#define REQ_ANY_CONTIGUOUS(flags) ((flags&PyBUF_ANY_CONTIGUOUS) == PyBUF_ANY_CONTIGUOUS)
+#define REQ_STRIDES(flags) ((flags&PyBUF_STRIDES) == PyBUF_STRIDES)
+#define REQ_SHAPE(flags) ((flags&PyBUF_ND) == PyBUF_ND)
+#define REQ_WRITABLE(flags) (flags&PyBUF_WRITABLE)
+#define REQ_FORMAT(flags) (flags&PyBUF_FORMAT)
+
+
 PyDoc_STRVAR(memory_doc,
 "memoryview(object)\n\
 \n\
 Create a new memoryview object which references the given object.");
 
+
+/**************************************************************************/
+/*                       Copy memoryview buffers                          */
+/**************************************************************************/
+
+/* The functions in this section take a source and a destination buffer
+   with the same logical structure: format, itemsize, ndim and shape
+   are identical, with ndim > 0.
+
+   NOTE: All buffers are assumed to have PyBUF_FULL information, which
+   is the case for memoryviews! */
+
+
+/* Assumptions: ndim >= 1. The macro tests for a corner case that should
+   perhaps be explicitly forbidden in the PEP. */
+#define HAVE_SUBOFFSETS_IN_LAST_DIM(view) \
+    (view->suboffsets && view->suboffsets[dest->ndim-1] >= 0)
+
+Py_LOCAL_INLINE(int)
+last_dim_is_contiguous(Py_buffer *dest, Py_buffer *src)
+{
+    assert(dest->ndim > 0 && src->ndim > 0);
+    return (!HAVE_SUBOFFSETS_IN_LAST_DIM(dest) &&
+            !HAVE_SUBOFFSETS_IN_LAST_DIM(src) &&
+            dest->strides[dest->ndim-1] == dest->itemsize &&
+            src->strides[src->ndim-1] == src->itemsize);
+}
+
+/* Check that the logical structure of the destination and source buffers
+   is identical. */
+static int
+cmp_structure(Py_buffer *dest, Py_buffer *src)
+{
+    const char *dfmt, *sfmt;
+    int i;
+
+    assert(dest->format && src->format);
+    dfmt = dest->format[0] == '@' ? dest->format+1 : dest->format;
+    sfmt = src->format[0] == '@' ? src->format+1 : src->format;
+
+    if (strcmp(dfmt, sfmt) != 0 ||
+        dest->itemsize != src->itemsize ||
+        dest->ndim != src->ndim) {
+        goto value_error;
+    }
+
+    for (i = 0; i < dest->ndim; i++) {
+        if (dest->shape[i] != src->shape[i])
+            goto value_error;
+        if (dest->shape[i] == 0)
+            break;
+    }
+
+    return 0;
+
+value_error:
+    PyErr_SetString(PyExc_ValueError,
+        "ndarray assignment: lvalue and rvalue have different structures");
+    return -1;
+}
+
+/* Base case for recursive multi-dimensional copying. Contiguous arrays are
+   copied with very little overhead. Assumptions: ndim == 1, mem == NULL or
+   sizeof(mem) == shape[0] * itemsize. */
+static void
+copy_base(const Py_ssize_t *shape, Py_ssize_t itemsize,
+          char *dptr, const Py_ssize_t *dstrides, const Py_ssize_t *dsuboffsets,
+          char *sptr, const Py_ssize_t *sstrides, const Py_ssize_t *ssuboffsets,
+          char *mem)
+{
+    if (mem == NULL) { /* contiguous */
+        Py_ssize_t size = shape[0] * itemsize;
+        if (dptr + size < sptr || sptr + size < dptr)
+            memcpy(dptr, sptr, size); /* no overlapping */
+        else
+            memmove(dptr, sptr, size);
+    }
+    else {
+        char *p;
+        Py_ssize_t i;
+        for (i=0, p=mem; i < shape[0]; p+=itemsize, sptr+=sstrides[0], i++) {
+            char *xsptr = ADJUST_PTR(sptr, ssuboffsets);
+            memcpy(p, xsptr, itemsize);
+        }
+        for (i=0, p=mem; i < shape[0]; p+=itemsize, dptr+=dstrides[0], i++) {
+            char *xdptr = ADJUST_PTR(dptr, dsuboffsets);
+            memcpy(xdptr, p, itemsize);
+        }
+    }
+
+}
+
+/* Recursively copy a source buffer to a destination buffer. The two buffers
+   have the same ndim, shape and itemsize. */
+static void
+copy_rec(const Py_ssize_t *shape, Py_ssize_t ndim, Py_ssize_t itemsize,
+         char *dptr, const Py_ssize_t *dstrides, const Py_ssize_t *dsuboffsets,
+         char *sptr, const Py_ssize_t *sstrides, const Py_ssize_t *ssuboffsets,
+         char *mem)
+{
+    Py_ssize_t i;
+
+    assert(ndim >= 1);
+
+    if (ndim == 1) {
+        copy_base(shape, itemsize,
+                  dptr, dstrides, dsuboffsets,
+                  sptr, sstrides, ssuboffsets,
+                  mem);
+        return;
+    }
+
+    for (i = 0; i < shape[0]; dptr+=dstrides[0], sptr+=sstrides[0], i++) {
+        char *xdptr = ADJUST_PTR(dptr, dsuboffsets);
+        char *xsptr = ADJUST_PTR(sptr, ssuboffsets);
+
+        copy_rec(shape+1, ndim-1, itemsize,
+                 xdptr, dstrides+1, dsuboffsets ? dsuboffsets+1 : NULL,
+                 xsptr, sstrides+1, ssuboffsets ? ssuboffsets+1 : NULL,
+                 mem);
+    }
+}
+
+/* Faster copying of one-dimensional arrays. */
+static int
+copy_single(Py_buffer *dest, Py_buffer *src)
+{
+    char *mem = NULL;
+
+    assert(dest->ndim == 1);
+
+    if (cmp_structure(dest, src) < 0)
+        return -1;
+
+    if (!last_dim_is_contiguous(dest, src)) {
+        mem = PyMem_Malloc(dest->shape[0] * dest->itemsize);
+        if (mem == NULL) {
+            PyErr_NoMemory();
+            return -1;
+        }
+    }
+
+    copy_base(dest->shape, dest->itemsize,
+              dest->buf, dest->strides, dest->suboffsets,
+              src->buf, src->strides, src->suboffsets,
+              mem);
+
+    if (mem)
+        PyMem_Free(mem);
+
+    return 0;
+}
+
+/* Recursively copy src to dest. Both buffers must have the same basic
+   structure. Copying is atomic, the function never fails with a partial
+   copy. */
+static int
+copy_buffer(Py_buffer *dest, Py_buffer *src)
+{
+    char *mem = NULL;
+
+    assert(dest->ndim > 0);
+
+    if (cmp_structure(dest, src) < 0)
+        return -1;
+
+    if (!last_dim_is_contiguous(dest, src)) {
+        mem = PyMem_Malloc(dest->shape[dest->ndim-1] * dest->itemsize);
+        if (mem == NULL) {
+            PyErr_NoMemory();
+            return -1;
+        }
+    }
+
+    copy_rec(dest->shape, dest->ndim, dest->itemsize,
+             dest->buf, dest->strides, dest->suboffsets,
+             src->buf, src->strides, src->suboffsets,
+             mem);
+
+    if (mem)
+        PyMem_Free(mem);
+
+    return 0;
+}
+
+/* Initialize strides for a C-contiguous array. */
+Py_LOCAL_INLINE(void)
+init_strides_from_shape(Py_buffer *view)
+{
+    Py_ssize_t i;
+
+    assert(view->ndim > 0);
+
+    view->strides[view->ndim-1] = view->itemsize;
+    for (i = view->ndim-2; i >= 0; i--)
+        view->strides[i] = view->strides[i+1] * view->shape[i+1];
+}
+
+/* Initialize strides for a Fortran-contiguous array. */
+Py_LOCAL_INLINE(void)
+init_fortran_strides_from_shape(Py_buffer *view)
+{
+    Py_ssize_t i;
+
+    assert(view->ndim > 0);
+
+    view->strides[0] = view->itemsize;
+    for (i = 1; i < view->ndim; i++)
+        view->strides[i] = view->strides[i-1] * view->shape[i-1];
+}
+
+/* Copy src to a C-contiguous representation. Assumptions:
+   len(mem) == src->len. */
+static int
+buffer_to_c_contiguous(char *mem, Py_buffer *src)
+{
+    Py_buffer dest;
+    Py_ssize_t *strides;
+    int ret;
+
+    assert(src->shape != NULL);
+    assert(src->strides != NULL);
+
+    strides = PyMem_Malloc(src->ndim * (sizeof *src->strides));
+    if (strides == NULL) {
+        PyErr_NoMemory();
+        return -1;
+    }
+
+    /* initialize dest as a C-contiguous buffer */
+    dest = *src;
+    dest.buf = mem;
+    /* shape is constant and shared */
+    dest.strides = strides;
+    init_strides_from_shape(&dest);
+    dest.suboffsets = NULL;
+
+    ret = copy_buffer(&dest, src);
+
+    PyMem_Free(strides);
+    return ret;
+}
+
+
+/****************************************************************************/
+/*                               Constructors                               */
+/****************************************************************************/
+
+/* Initialize values that are shared with the managed buffer. */
+Py_LOCAL_INLINE(void)
+init_shared_values(Py_buffer *dest, const Py_buffer *src)
+{
+    dest->obj = src->obj;
+    dest->buf = src->buf;
+    dest->len = src->len;
+    dest->itemsize = src->itemsize;
+    dest->readonly = src->readonly;
+    dest->format = src->format ? src->format : "B";
+    dest->internal = src->internal;
+}
+
+/* Copy shape and strides. Reconstruct missing values. */
+static void
+init_shape_strides(Py_buffer *dest, const Py_buffer *src)
+{
+    Py_ssize_t i;
+
+    if (src->ndim == 0) {
+        dest->shape = NULL;
+        dest->strides = NULL;
+        return;
+    }
+    if (src->ndim == 1) {
+        dest->shape[0] = src->shape ? src->shape[0] : src->len / src->itemsize;
+        dest->strides[0] = src->strides ? src->strides[0] : src->itemsize;
+        return;
+    }
+
+    for (i = 0; i < src->ndim; i++)
+        dest->shape[i] = src->shape[i];
+    if (src->strides) {
+        for (i = 0; i < src->ndim; i++)
+            dest->strides[i] = src->strides[i];
+    }
+    else {
+        init_strides_from_shape(dest);
+    }
+}
+
+Py_LOCAL_INLINE(void)
+init_suboffsets(Py_buffer *dest, const Py_buffer *src)
+{
+    Py_ssize_t i;
+
+    if (src->suboffsets == NULL) {
+        dest->suboffsets = NULL;
+        return;
+    }
+    for (i = 0; i < src->ndim; i++)
+        dest->suboffsets[i] = src->suboffsets[i];
+}
+
+/* len = product(shape) * itemsize */
+Py_LOCAL_INLINE(void)
+init_len(Py_buffer *view)
+{
+    Py_ssize_t i, len;
+
+    len = 1;
+    for (i = 0; i < view->ndim; i++)
+        len *= view->shape[i];
+    len *= view->itemsize;
+
+    view->len = len;
+}
+
+/* Initialize memoryview buffer properties. */
+static void
+init_flags(PyMemoryViewObject *mv)
+{
+    const Py_buffer *view = &mv->view;
+    int flags = 0;
+
+    switch (view->ndim) {
+    case 0:
+        flags |= (_Py_MEMORYVIEW_SCALAR|_Py_MEMORYVIEW_C|
+                  _Py_MEMORYVIEW_FORTRAN);
+        break;
+    case 1:
+        if (MV_CONTIGUOUS_NDIM1(view))
+            flags |= (_Py_MEMORYVIEW_C|_Py_MEMORYVIEW_FORTRAN);
+        break;
+    default:
+        if (PyBuffer_IsContiguous(view, 'C'))
+            flags |= _Py_MEMORYVIEW_C;
+        if (PyBuffer_IsContiguous(view, 'F'))
+            flags |= _Py_MEMORYVIEW_FORTRAN;
+        break;
+    }
+
+    if (view->suboffsets) {
+        flags |= _Py_MEMORYVIEW_PIL;
+        flags &= ~(_Py_MEMORYVIEW_C|_Py_MEMORYVIEW_FORTRAN);
+    }
+
+    mv->flags = flags;
+}
+
+/* Allocate a new memoryview and perform basic initialization. New memoryviews
+   are exclusively created through the mbuf_add functions. */
+Py_LOCAL_INLINE(PyMemoryViewObject *)
+memory_alloc(int ndim)
+{
+    PyMemoryViewObject *mv;
+
+    mv = (PyMemoryViewObject *)
+        PyObject_GC_NewVar(PyMemoryViewObject, &PyMemoryView_Type, 3*ndim);
+    if (mv == NULL)
+        return NULL;
+
+    mv->mbuf = NULL;
+    mv->hash = -1;
+    mv->flags = 0;
+    mv->exports = 0;
+    mv->view.ndim = ndim;
+    mv->view.shape = mv->ob_array;
+    mv->view.strides = mv->ob_array + ndim;
+    mv->view.suboffsets = mv->ob_array + 2 * ndim;
+
+    _PyObject_GC_TRACK(mv);
+    return mv;
+}
+
+/*
+   Return a new memoryview that is registered with mbuf. If src is NULL,
+   use mbuf->master as the underlying buffer. Otherwise, use src.
+
+   The new memoryview has full buffer information: shape and strides
+   are always present, suboffsets as needed. Arrays are copied to
+   the memoryview's ob_array field.
+ */
+static PyObject *
+mbuf_add_view(_PyManagedBufferObject *mbuf, const Py_buffer *src)
+{
+    PyMemoryViewObject *mv;
+    Py_buffer *dest;
+
+    if (src == NULL)
+        src = &mbuf->master;
+
+    if (src->ndim > PyBUF_MAX_NDIM) {
+        PyErr_SetString(PyExc_ValueError,
+            "memoryview: number of dimensions must not exceed "
+            STRINGIZE(PyBUF_MAX_NDIM));
+        return NULL;
+    }
+
+    mv = memory_alloc(src->ndim);
+    if (mv == NULL)
+        return NULL;
+
+    dest = &mv->view;
+    init_shared_values(dest, src);
+    init_shape_strides(dest, src);
+    init_suboffsets(dest, src);
+    init_flags(mv);
+
+    mv->mbuf = mbuf;
+    Py_INCREF(mbuf);
+    mbuf->exports++;
+
+    return (PyObject *)mv;
+}
+
+/* Register an incomplete view: shape, strides, suboffsets and flags still
+   need to be initialized. Use 'ndim' instead of src->ndim to determine the
+   size of the memoryview's ob_array.
+
+   Assumption: ndim <= PyBUF_MAX_NDIM. */
+static PyObject *
+mbuf_add_incomplete_view(_PyManagedBufferObject *mbuf, const Py_buffer *src,
+                         int ndim)
+{
+    PyMemoryViewObject *mv;
+    Py_buffer *dest;
+
+    if (src == NULL)
+        src = &mbuf->master;
+
+    assert(ndim <= PyBUF_MAX_NDIM);
+
+    mv = memory_alloc(ndim);
+    if (mv == NULL)
+        return NULL;
+
+    dest = &mv->view;
+    init_shared_values(dest, src);
+
+    mv->mbuf = mbuf;
+    Py_INCREF(mbuf);
+    mbuf->exports++;
+
+    return (PyObject *)mv;
+}
+
+/* Expose a raw memory area as a view of contiguous bytes. flags can be
+   PyBUF_READ or PyBUF_WRITE. view->format is set to "B" (unsigned bytes).
+   The memoryview has complete buffer information. */
+PyObject *
+PyMemoryView_FromMemory(char *mem, Py_ssize_t size, int flags)
+{
+    _PyManagedBufferObject *mbuf;
+    PyObject *mv;
+    int readonly;
+
+    assert(mem != NULL);
+    assert(flags == PyBUF_READ || flags == PyBUF_WRITE);
+
+    mbuf = mbuf_alloc();
+    if (mbuf == NULL)
+        return NULL;
+
+    readonly = (flags == PyBUF_WRITE) ? 0 : 1;
+    (void)PyBuffer_FillInfo(&mbuf->master, NULL, mem, size, readonly,
+                            PyBUF_FULL_RO);
+
+    mv = mbuf_add_view(mbuf, NULL);
+    Py_DECREF(mbuf);
+
+    return mv;
+}
+
+/* Create a memoryview from a given Py_buffer. For simple byte views,
+   PyMemoryView_FromMemory() should be used instead.
+   This function is the only entry point that can create a master buffer
+   without full information. Because of this fact init_shape_strides()
+   must be able to reconstruct missing values.  */
 PyObject *
 PyMemoryView_FromBuffer(Py_buffer *info)
 {
-    PyMemoryViewObject *mview;
+    _PyManagedBufferObject *mbuf;
+    PyObject *mv;
 
     if (info->buf == NULL) {
         PyErr_SetString(PyExc_ValueError,
-            "cannot make memory view from a buffer with a NULL data pointer");
+            "PyMemoryView_FromBuffer(): info->buf must not be NULL");
         return NULL;
     }
-    mview = (PyMemoryViewObject *)
-        PyObject_GC_New(PyMemoryViewObject, &PyMemoryView_Type);
-    if (mview == NULL)
+
+    mbuf = mbuf_alloc();
+    if (mbuf == NULL)
         return NULL;
-    mview->hash = -1;
-    dup_buffer(&mview->view, info);
-    /* NOTE: mview->view.obj should already have been incref'ed as
-       part of PyBuffer_FillInfo(). */
-    _PyObject_GC_TRACK(mview);
-    return (PyObject *)mview;
+
+    /* info->obj is either NULL or a borrowed reference. This reference
+       should not be decremented in PyBuffer_Release(). */
+    mbuf->master = *info;
+    mbuf->master.obj = NULL;
+
+    mv = mbuf_add_view(mbuf, NULL);
+    Py_DECREF(mbuf);
+
+    return mv;
 }
 
+/* Create a memoryview from an object that implements the buffer protocol.
+   If the object is a memoryview, the new memoryview must be registered
+   with the same managed buffer. Otherwise, a new managed buffer is created. */
 PyObject *
-PyMemoryView_FromObject(PyObject *base)
+PyMemoryView_FromObject(PyObject *v)
 {
-    PyMemoryViewObject *mview;
-    Py_buffer view;
+    _PyManagedBufferObject *mbuf;
 
-    if (!PyObject_CheckBuffer(base)) {
-        PyErr_SetString(PyExc_TypeError,
-            "cannot make memory view because object does "
-            "not have the buffer interface");
+    if (PyMemoryView_Check(v)) {
+        PyMemoryViewObject *mv = (PyMemoryViewObject *)v;
+        CHECK_RELEASED(mv);
+        return mbuf_add_view(mv->mbuf, &mv->view);
+    }
+    else if (PyObject_CheckBuffer(v)) {
+        PyObject *ret;
+        mbuf = (_PyManagedBufferObject *)_PyManagedBuffer_FromObject(v);
+        if (mbuf == NULL)
+            return NULL;
+        ret = mbuf_add_view(mbuf, NULL);
+        Py_DECREF(mbuf);
+        return ret;
+    }
+
+    PyErr_Format(PyExc_TypeError,
+        "memoryview: %.200s object does not have the buffer interface",
+        Py_TYPE(v)->tp_name);
+    return NULL;
+}
+
+/* Copy the format string from a base object that might vanish. */
+static int
+mbuf_copy_format(_PyManagedBufferObject *mbuf, const char *fmt)
+{
+    if (fmt != NULL) {
+        char *cp = PyMem_Malloc(strlen(fmt)+1);
+        if (cp == NULL) {
+            PyErr_NoMemory();
+            return -1;
+        }
+        mbuf->master.format = strcpy(cp, fmt);
+        mbuf->flags |= _Py_MANAGED_BUFFER_FREE_FORMAT;
+    }
+
+    return 0;
+}
+
+/*
+   Return a memoryview that is based on a contiguous copy of src.
+   Assumptions: src has PyBUF_FULL_RO information, src->ndim > 0.
+
+   Ownership rules:
+     1) As usual, the returned memoryview has a private copy
+        of src->shape, src->strides and src->suboffsets.
+     2) src->format is copied to the master buffer and released
+        in mbuf_dealloc(). The releasebufferproc of the bytes
+        object is NULL, so it does not matter that mbuf_release()
+        passes the altered format pointer to PyBuffer_Release().
+*/
+static PyObject *
+memory_from_contiguous_copy(Py_buffer *src, char order)
+{
+    _PyManagedBufferObject *mbuf;
+    PyMemoryViewObject *mv;
+    PyObject *bytes;
+    Py_buffer *dest;
+    int i;
+
+    assert(src->ndim > 0);
+    assert(src->shape != NULL);
+
+    bytes = PyBytes_FromStringAndSize(NULL, src->len);
+    if (bytes == NULL)
+        return NULL;
+
+    mbuf = (_PyManagedBufferObject *)_PyManagedBuffer_FromObject(bytes);
+    Py_DECREF(bytes);
+    if (mbuf == NULL)
+        return NULL;
+
+    if (mbuf_copy_format(mbuf, src->format) < 0) {
+        Py_DECREF(mbuf);
+        return NULL;
+    }
+
+    mv = (PyMemoryViewObject *)mbuf_add_incomplete_view(mbuf, NULL, src->ndim);
+    Py_DECREF(mbuf);
+    if (mv == NULL)
         return NULL;
+
+    dest = &mv->view;
+
+    /* shared values are initialized correctly except for itemsize */
+    dest->itemsize = src->itemsize;
+
+    /* shape and strides */
+    for (i = 0; i < src->ndim; i++) {
+        dest->shape[i] = src->shape[i];
+    }
+    if (order == 'C' || order == 'A') {
+        init_strides_from_shape(dest);
     }
+    else {
+        init_fortran_strides_from_shape(dest);
+    }
+    /* suboffsets */
+    dest->suboffsets = NULL;
+
+    /* flags */
+    init_flags(mv);
+
+    if (copy_buffer(dest, src) < 0) {
+        Py_DECREF(mv);
+        return NULL;
+    }
+
+    return (PyObject *)mv;
+}
+
+/*
+   Return a new memoryview object based on a contiguous exporter with
+   buffertype={PyBUF_READ, PyBUF_WRITE} and order={'C', 'F'ortran, or 'A'ny}.
+   The logical structure of the input and output buffers is the same
+   (i.e. tolist(input) == tolist(output)), but the physical layout in
+   memory can be explicitly chosen.
+ 
+   As usual, if buffertype=PyBUF_WRITE, the exporter's buffer must be writable,
+   otherwise it may be writable or read-only.
+
+   If the exporter is already contiguous with the desired target order,
+   the memoryview will be directly based on the exporter.
+
+   Otherwise, if the buffertype is PyBUF_READ, the memoryview will be
+   based on a new bytes object. If order={'C', 'A'ny}, use 'C' order,
+   'F'ortran order otherwise.
+*/
+PyObject *
+PyMemoryView_GetContiguous(PyObject *obj, int buffertype, char order)
+{
+    PyMemoryViewObject *mv;
+    PyObject *ret;
+    Py_buffer *view;
+
+    assert(buffertype == PyBUF_READ || buffertype == PyBUF_WRITE);
+    assert(order == 'C' || order == 'F' || order == 'A');
 
-    if (PyObject_GetBuffer(base, &view, PyBUF_FULL_RO) < 0)
+    mv = (PyMemoryViewObject *)PyMemoryView_FromObject(obj);
+    if (mv == NULL)
         return NULL;
 
-    mview = (PyMemoryViewObject *)PyMemoryView_FromBuffer(&view);
-    if (mview == NULL) {
-        PyBuffer_Release(&view);
+    view = &mv->view;
+    if (buffertype == PyBUF_WRITE && view->readonly) {
+        PyErr_SetString(PyExc_BufferError,
+            "underlying buffer is not writable");
+        Py_DECREF(mv);
+        return NULL;
+    }
+
+    if (PyBuffer_IsContiguous(view, order))
+        return (PyObject *)mv;
+
+    if (buffertype == PyBUF_WRITE) {
+        PyErr_SetString(PyExc_BufferError,
+            "writable contiguous buffer requested "
+            "for a non-contiguous object.");
+        Py_DECREF(mv);
         return NULL;
     }
 
-    return (PyObject *)mview;
+    ret = memory_from_contiguous_copy(view, order);
+    Py_DECREF(mv);
+    return ret;
 }
 
+
 static PyObject *
 memory_new(PyTypeObject *subtype, PyObject *args, PyObject *kwds)
 {
     PyObject *obj;
-    static char *kwlist[] = {"object", 0};
+    static char *kwlist[] = {"object", NULL};
 
     if (!PyArg_ParseTupleAndKeywords(args, kwds, "O:memoryview", kwlist,
                                      &obj)) {
@@ -132,478 +923,1106 @@ memory_new(PyTypeObject *subtype, PyObject *args, PyObject *kwds)
 }
 
 
+/****************************************************************************/
+/*                           Release/GC management                          */
+/****************************************************************************/
+
+/* Inform the managed buffer that this particular memoryview will not access
+   the underlying buffer again. If no other memoryviews are registered with
+   the managed buffer, the underlying buffer is released instantly and
+   marked as inaccessible for both the memoryview and the managed buffer.
+
+   This function fails if the memoryview itself has exported buffers. */
+static int
+_memory_release(PyMemoryViewObject *self)
+{
+    if (self->flags & _Py_MEMORYVIEW_RELEASED)
+        return 0;
+
+    if (self->exports == 0) {
+        self->flags |= _Py_MEMORYVIEW_RELEASED;
+        assert(self->mbuf->exports > 0);
+        if (--self->mbuf->exports == 0)
+            mbuf_release(self->mbuf);
+        return 0;
+    }
+    if (self->exports > 0) {
+        PyErr_Format(PyExc_BufferError,
+            "memoryview has %zd exported buffer%s", self->exports,
+            self->exports==1 ? "" : "s");
+        return -1;
+    }
+
+    Py_FatalError("_memory_release(): negative export count");
+    return -1;
+}
+
+static PyObject *
+memory_release(PyMemoryViewObject *self)
+{
+    if (_memory_release(self) < 0)
+        return NULL;
+    Py_RETURN_NONE;
+}
+
 static void
-_strided_copy_nd(char *dest, char *src, int nd, Py_ssize_t *shape,
-                 Py_ssize_t *strides, Py_ssize_t itemsize, char fort)
+memory_dealloc(PyMemoryViewObject *self)
 {
-    int k;
-    Py_ssize_t outstride;
+    assert(self->exports == 0);
+    _PyObject_GC_UNTRACK(self);
+    (void)_memory_release(self);
+    Py_CLEAR(self->mbuf);
+    PyObject_GC_Del(self);
+}
 
-    if (nd==0) {
-        memcpy(dest, src, itemsize);
-    }
-    else if (nd == 1) {
-        for (k = 0; k<shape[0]; k++) {
-            memcpy(dest, src, itemsize);
-            dest += itemsize;
-            src += strides[0];
-        }
+static int
+memory_traverse(PyMemoryViewObject *self, visitproc visit, void *arg)
+{
+    Py_VISIT(self->mbuf);
+    return 0;
+}
+
+static int
+memory_clear(PyMemoryViewObject *self)
+{
+    (void)_memory_release(self);
+    Py_CLEAR(self->mbuf);
+    return 0;
+}
+
+static PyObject *
+memory_enter(PyObject *self, PyObject *args)
+{
+    CHECK_RELEASED(self);
+    Py_INCREF(self);
+    return self;
+}
+
+static PyObject *
+memory_exit(PyObject *self, PyObject *args)
+{
+    return memory_release((PyMemoryViewObject *)self);
+}
+
+
+/****************************************************************************/
+/*                         Casting format and shape                         */
+/****************************************************************************/
+
+#define IS_BYTE_FORMAT(f) (f == 'b' || f == 'B' || f == 'c')
+
+Py_LOCAL_INLINE(Py_ssize_t)
+get_native_fmtchar(char *result, const char *fmt)
+{
+    Py_ssize_t size = -1;
+
+    if (fmt[0] == '@') fmt++;
+
+    switch (fmt[0]) {
+    case 'c': case 'b': case 'B': size = sizeof(char); break;
+    case 'h': case 'H': size = sizeof(short); break;
+    case 'i': case 'I': size = sizeof(int); break;
+    case 'l': case 'L': size = sizeof(long); break;
+    #ifdef HAVE_LONG_LONG
+    case 'q': case 'Q': size = sizeof(PY_LONG_LONG); break;
+    #endif
+    case 'n': case 'N': size = sizeof(Py_ssize_t); break;
+    case 'f': size = sizeof(float); break;
+    case 'd': size = sizeof(double); break;
+    #ifdef HAVE_C99_BOOL
+    case '?': size = sizeof(_Bool); break;
+    #else
+    case '?': size = sizeof(char); break;
+    #endif
+    case 'P': size = sizeof(void *); break;
     }
-    else {
-        if (fort == 'F') {
-            /* Copy first dimension first,
-               second dimension second, etc...
-               Set up the recursive loop backwards so that final
-               dimension is actually copied last.
-            */
-            outstride = itemsize;
-            for (k=1; k<nd-1;k++) {
-                outstride *= shape[k];
-            }
-            for (k=0; k<shape[nd-1]; k++) {
-                _strided_copy_nd(dest, src, nd-1, shape,
-                                 strides, itemsize, fort);
-                dest += outstride;
-                src += strides[nd-1];
-            }
-        }
 
-        else {
-            /* Copy last dimension first,
-               second-to-last dimension second, etc.
-               Set up the recursion so that the
-               first dimension is copied last
-            */
-            outstride = itemsize;
-            for (k=1; k < nd; k++) {
-                outstride *= shape[k];
-            }
-            for (k=0; k<shape[0]; k++) {
-                _strided_copy_nd(dest, src, nd-1, shape+1,
-                                 strides+1, itemsize,
-                                 fort);
-                dest += outstride;
-                src += strides[0];
-            }
-        }
+    if (size > 0 && fmt[1] == '\0') {
+        *result = fmt[0];
+        return size;
     }
-    return;
+
+    return -1;
 }
 
+/* Cast a memoryview's data type to 'format'. The input array must be
+   C-contiguous. At least one of input-format, output-format must have
+   byte size. The output array is 1-D, with the same byte length as the
+   input array. Thus, view->len must be a multiple of the new itemsize. */
 static int
-_indirect_copy_nd(char *dest, Py_buffer *view, char fort)
+cast_to_1D(PyMemoryViewObject *mv, PyObject *format)
 {
-    Py_ssize_t *indices;
-    int k;
-    Py_ssize_t elements;
-    char *ptr;
-    void (*func)(int, Py_ssize_t *, const Py_ssize_t *);
+    Py_buffer *view = &mv->view;
+    PyObject *asciifmt;
+    char srcchar, destchar;
+    Py_ssize_t itemsize;
+    int ret = -1;
+
+    assert(view->ndim >= 1);
+    assert(Py_SIZE(mv) == 3*view->ndim);
+    assert(view->shape == mv->ob_array);
+    assert(view->strides == mv->ob_array + view->ndim);
+    assert(view->suboffsets == mv->ob_array + 2*view->ndim);
+
+    if (get_native_fmtchar(&srcchar, view->format) < 0) {
+        PyErr_SetString(PyExc_ValueError,
+            "memoryview: source format must be a native single character "
+            "format prefixed with an optional '@'");
+        return ret;
+    }
 
-    if (view->ndim > PY_SSIZE_T_MAX / sizeof(Py_ssize_t)) {
-        PyErr_NoMemory();
-        return -1;
+    asciifmt = PyUnicode_AsASCIIString(format);
+    if (asciifmt == NULL)
+        return ret;
+
+    itemsize = get_native_fmtchar(&destchar, PyBytes_AS_STRING(asciifmt));
+    if (itemsize < 0) {
+        PyErr_SetString(PyExc_ValueError,
+            "memoryview: destination format must be a native single "
+            "character format prefixed with an optional '@'");
+        goto out;
     }
 
-    indices = (Py_ssize_t *)PyMem_Malloc(sizeof(Py_ssize_t)*view->ndim);
-    if (indices == NULL) {
-        PyErr_NoMemory();
-        return -1;
+    if (!IS_BYTE_FORMAT(srcchar) && !IS_BYTE_FORMAT(destchar)) {
+        PyErr_SetString(PyExc_TypeError,
+            "memoryview: cannot cast between two non-byte formats");
+        goto out;
     }
-    for (k=0; k<view->ndim;k++) {
-        indices[k] = 0;
+    if (view->len % itemsize) {
+        PyErr_SetString(PyExc_TypeError,
+            "memoryview: length is not a multiple of itemsize");
+        goto out;
     }
 
-    elements = 1;
-    for (k=0; k<view->ndim; k++) {
-        elements *= view->shape[k];
+    strncpy(mv->format, PyBytes_AS_STRING(asciifmt),
+            _Py_MEMORYVIEW_MAX_FORMAT);
+    mv->format[_Py_MEMORYVIEW_MAX_FORMAT-1] = '\0';
+    view->format = mv->format;
+    view->itemsize = itemsize;
+
+    view->ndim = 1;
+    view->shape[0] = view->len / view->itemsize;
+    view->strides[0] = view->itemsize;
+    view->suboffsets = NULL;
+
+    init_flags(mv);
+ 
+    ret = 0;
+
+out:
+    Py_DECREF(asciifmt);
+    return ret;
+}
+
+/* The memoryview must have space for 3*len(seq) elements. */
+static Py_ssize_t
+copy_shape(Py_ssize_t *shape, const PyObject *seq, Py_ssize_t ndim,
+           Py_ssize_t itemsize)
+{
+    Py_ssize_t x, i;
+    Py_ssize_t len = itemsize;
+
+    for (i = 0; i < ndim; i++) {
+        PyObject *tmp = PySequence_Fast_GET_ITEM(seq, i);
+        if (!PyLong_Check(tmp)) {
+            PyErr_SetString(PyExc_TypeError,
+                "memoryview.cast(): elements of shape must be integers");
+            return -1;
+        }
+        x = PyLong_AsSsize_t(tmp);
+        if (x == -1 && PyErr_Occurred()) {
+            return -1;
+        }
+        if (x <= 0) {
+            /* In general elements of shape may be 0, but not for casting. */
+            PyErr_Format(PyExc_ValueError,
+                "memoryview.cast(): elements of shape must be integers > 0");
+            return -1;
+        }
+        if (x > PY_SSIZE_T_MAX / len) {
+            PyErr_Format(PyExc_ValueError,
+                "memoryview.cast(): product(shape) > SSIZE_MAX");
+            return -1;
+        }
+        len *= x;
+        shape[i] = x;
     }
-    if (fort == 'F') {
-        func = _Py_add_one_to_index_F;
+
+    return len;
+}
+
+/* Cast a 1-D array to a new shape. The result array will be C-contiguous.
+   If the result array does not have exactly the same byte length as the
+   input array, raise ValueError. */
+static int
+cast_to_ND(PyMemoryViewObject *mv, const PyObject *shape, int ndim)
+{
+    Py_buffer *view = &mv->view;
+    Py_ssize_t len;
+
+    assert(view->ndim == 1); /* ndim from cast_to_1D() */
+    assert(Py_SIZE(mv) == 3*(ndim==0?1:ndim)); /* ndim of result array */
+    assert(view->shape == mv->ob_array);
+    assert(view->strides == mv->ob_array + (ndim==0?1:ndim));
+    assert(view->suboffsets == NULL);
+
+    view->ndim = ndim;
+    if (view->ndim == 0) {
+        view->shape = NULL;
+        view->strides = NULL;
+        len = view->itemsize;
     }
     else {
-        func = _Py_add_one_to_index_C;
+        len = copy_shape(view->shape, shape, ndim, view->itemsize);
+        if (len < 0)
+            return -1;
+        init_strides_from_shape(view);
     }
-    while (elements--) {
-        func(view->ndim, indices, view->shape);
-        ptr = PyBuffer_GetPointer(view, indices);
-        memcpy(dest, ptr, view->itemsize);
-        dest += view->itemsize;
+
+    if (view->len != len) {
+        PyErr_SetString(PyExc_TypeError,
+            "memoryview: product(shape) * itemsize != buffer size");
+        return -1;
     }
 
-    PyMem_Free(indices);
+    init_flags(mv);
+
+    return 0;
+}
+
+static int
+zero_in_shape(PyMemoryViewObject *mv)
+{
+    Py_buffer *view = &mv->view;
+    Py_ssize_t i;
+
+    for (i = 0; i < view->ndim; i++)
+        if (view->shape[i] == 0)
+            return 1;
+
     return 0;
 }
 
 /*
-   Get a the data from an object as a contiguous chunk of memory (in
-   either 'C' or 'F'ortran order) even if it means copying it into a
-   separate memory area.
-
-   Returns a new reference to a Memory view object.  If no copy is needed,
-   the memory view object points to the original memory and holds a
-   lock on the original.  If a copy is needed, then the memory view object
-   points to a brand-new Bytes object (and holds a memory lock on it).
-
-   buffertype
-
-   PyBUF_READ  buffer only needs to be read-only
-   PyBUF_WRITE buffer needs to be writable (give error if not contiguous)
-   PyBUF_SHADOW buffer needs to be writable so shadow it with
-                a contiguous buffer if it is not. The view will point to
-                the shadow buffer which can be written to and then
-                will be copied back into the other buffer when the memory
-                view is de-allocated.  While the shadow buffer is
-                being used, it will have an exclusive write lock on
-                the original buffer.
- */
+   Cast a copy of 'self' to a different view. The input view must
+   be C-contiguous. The function always casts the input view to a
+   1-D output according to 'format'. At least one of input-format,
+   output-format must have byte size.
 
-PyObject *
-PyMemoryView_GetContiguous(PyObject *obj, int buffertype, char fort)
+   If 'shape' is given, the 1-D view from the previous step will
+   be cast to a C-contiguous view with new shape and strides.
+
+   All casts must result in views that will have the exact byte
+   size of the original input. Otherwise, an error is raised.
+*/
+static PyObject *
+memory_cast(PyMemoryViewObject *self, PyObject *args, PyObject *kwds)
 {
-    PyMemoryViewObject *mem;
-    PyObject *bytes;
-    Py_buffer *view;
-    int flags;
-    char *dest;
+    static char *kwlist[] = {"format", "shape", NULL};
+    PyMemoryViewObject *mv = NULL;
+    PyObject *shape = NULL;
+    PyObject *format;
+    Py_ssize_t ndim = 1;
 
-    if (!PyObject_CheckBuffer(obj)) {
+    CHECK_RELEASED(self);
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|O", kwlist,
+                                     &format, &shape)) {
+        return NULL;
+    }
+    if (!PyUnicode_Check(format)) {
         PyErr_SetString(PyExc_TypeError,
-                        "object does not support the buffer interface");
+            "memoryview: format argument must be a string");
         return NULL;
     }
-
-    mem = PyObject_GC_New(PyMemoryViewObject, &PyMemoryView_Type);
-    if (mem == NULL)
+    if (!MV_C_CONTIGUOUS(self->flags)) {
+        PyErr_SetString(PyExc_TypeError,
+            "memoryview: casts are restricted to C-contiguous views");
         return NULL;
-
-    view = &mem->view;
-    flags = PyBUF_FULL_RO;
-    switch(buffertype) {
-    case PyBUF_WRITE:
-        flags = PyBUF_FULL;
-        break;
+    }
+    if (zero_in_shape(self)) {
+        PyErr_SetString(PyExc_TypeError,
+            "memoryview: cannot cast view with zeros in shape or strides");
+        return NULL;
+    }
+    if (shape) {
+        CHECK_LIST_OR_TUPLE(shape)
+        ndim = PySequence_Fast_GET_SIZE(shape);
+        if (ndim > PyBUF_MAX_NDIM) {
+            PyErr_SetString(PyExc_ValueError,
+                "memoryview: number of dimensions must not exceed "
+                STRINGIZE(PyBUF_MAX_NDIM));
+            return NULL;
+        }
+        if (self->view.ndim != 1 && ndim != 1) {
+            PyErr_SetString(PyExc_TypeError,
+                "memoryview: cast must be 1D -> ND or ND -> 1D");
+            return NULL;
+        }
     }
 
-    if (PyObject_GetBuffer(obj, view, flags) != 0) {
-        Py_DECREF(mem);
+    mv = (PyMemoryViewObject *)
+        mbuf_add_incomplete_view(self->mbuf, &self->view, ndim==0 ? 1 : (int)ndim);
+    if (mv == NULL)
         return NULL;
+
+    if (cast_to_1D(mv, format) < 0)
+        goto error;
+    if (shape && cast_to_ND(mv, shape, (int)ndim) < 0)
+        goto error;
+
+    return (PyObject *)mv;
+
+error:
+    Py_DECREF(mv);
+    return NULL;
+}
+
+
+/**************************************************************************/
+/*                               getbuffer                                */
+/**************************************************************************/
+
+static int
+memory_getbuf(PyMemoryViewObject *self, Py_buffer *view, int flags)
+{
+    Py_buffer *base = &self->view;
+    int baseflags = self->flags;
+
+    CHECK_RELEASED_INT(self);
+
+    /* start with complete information */
+    *view = *base;
+    view->obj = NULL;
+
+    if (REQ_WRITABLE(flags) && base->readonly) {
+        PyErr_SetString(PyExc_BufferError,
+            "memoryview: underlying buffer is not writable");
+        return -1;
+    }
+    if (!REQ_FORMAT(flags)) {
+        /* NULL indicates that the buffer's data type has been cast to 'B'.
+           view->itemsize is the _previous_ itemsize. If shape is present,
+           the equality product(shape) * itemsize = len still holds at this
+           point. The equality calcsize(format) = itemsize does _not_ hold
+           from here on! */
+        view->format = NULL;
     }
 
-    if (PyBuffer_IsContiguous(view, fort)) {
-        /* no copy needed */
-        _PyObject_GC_TRACK(mem);
-        return (PyObject *)mem;
+    if (REQ_C_CONTIGUOUS(flags) && !MV_C_CONTIGUOUS(baseflags)) {
+        PyErr_SetString(PyExc_BufferError,
+            "memoryview: underlying buffer is not C-contiguous");
+        return -1;
     }
-    /* otherwise a copy is needed */
-    if (buffertype == PyBUF_WRITE) {
-        Py_DECREF(mem);
+    if (REQ_F_CONTIGUOUS(flags) && !MV_F_CONTIGUOUS(baseflags)) {
         PyErr_SetString(PyExc_BufferError,
-                        "writable contiguous buffer requested "
-                        "for a non-contiguousobject.");
-        return NULL;
+            "memoryview: underlying buffer is not Fortran contiguous");
+        return -1;
     }
-    bytes = PyBytes_FromStringAndSize(NULL, view->len);
-    if (bytes == NULL) {
-        Py_DECREF(mem);
-        return NULL;
+    if (REQ_ANY_CONTIGUOUS(flags) && !MV_ANY_CONTIGUOUS(baseflags)) {
+        PyErr_SetString(PyExc_BufferError,
+            "memoryview: underlying buffer is not contiguous");
+        return -1;
     }
-    dest = PyBytes_AS_STRING(bytes);
-    /* different copying strategy depending on whether
-       or not any pointer de-referencing is needed
-    */
-    /* strided or in-direct copy */
-    if (view->suboffsets==NULL) {
-        _strided_copy_nd(dest, view->buf, view->ndim, view->shape,
-                         view->strides, view->itemsize, fort);
+    if (!REQ_INDIRECT(flags) && (baseflags & _Py_MEMORYVIEW_PIL)) {
+        PyErr_SetString(PyExc_BufferError,
+            "memoryview: underlying buffer requires suboffsets");
+        return -1;
     }
-    else {
-        if (_indirect_copy_nd(dest, view, fort) < 0) {
-            Py_DECREF(bytes);
-            Py_DECREF(mem);
-            return NULL;
+    if (!REQ_STRIDES(flags)) {
+        if (!MV_C_CONTIGUOUS(baseflags)) {
+            PyErr_SetString(PyExc_BufferError,
+                "memoryview: underlying buffer is not C-contiguous");
+            return -1;
         }
-        PyBuffer_Release(view);  /* XXX ? */
+        view->strides = NULL;
+    }
+    if (!REQ_SHAPE(flags)) {
+        /* PyBUF_SIMPLE or PyBUF_WRITABLE: at this point buf is C-contiguous,
+           so base->buf = ndbuf->data. */
+        if (view->format != NULL) {
+            /* PyBUF_SIMPLE|PyBUF_FORMAT and PyBUF_WRITABLE|PyBUF_FORMAT do
+               not make sense. */
+            PyErr_Format(PyExc_BufferError,
+                "ndarray: cannot cast to unsigned bytes if the format flag "
+                "is present");
+            return -1;
+        }
+        /* product(shape) * itemsize = len and calcsize(format) = itemsize
+           do _not_ hold from here on! */
+        view->ndim = 1;
+        view->shape = NULL;
     }
-    _PyObject_GC_TRACK(mem);
-    return (PyObject *)mem;
-}
 
 
-static PyObject *
-memory_format_get(PyMemoryViewObject *self)
+    view->obj = (PyObject *)self;
+    Py_INCREF(view->obj);
+    self->exports++;
+
+    return 0;
+}
+
+static void
+memory_releasebuf(PyMemoryViewObject *self, Py_buffer *view)
 {
-    CHECK_RELEASED(self);
-    return PyUnicode_FromString(self->view.format);
+    self->exports--;
+    return;
+    /* PyBuffer_Release() decrements view->obj after this function returns. */
 }
 
-static PyObject *
-memory_itemsize_get(PyMemoryViewObject *self)
+/* Buffer methods */
+static PyBufferProcs memory_as_buffer = {
+    (getbufferproc)memory_getbuf,         /* bf_getbuffer */
+    (releasebufferproc)memory_releasebuf, /* bf_releasebuffer */
+};
+
+
+/****************************************************************************/
+/*           Optimized pack/unpack for all native format specifiers         */
+/****************************************************************************/
+
+/*
+  Fix exceptions:
+     1) Include format string in the error message.
+     2) OverflowError -> ValueError.
+     3) The error message from PyNumber_Index() is not ideal.
+*/
+static int
+type_error_int(const char *fmt)
 {
-    CHECK_RELEASED(self);
-    return PyLong_FromSsize_t(self->view.itemsize);
+    PyErr_Format(PyExc_TypeError,
+        "memoryview: invalid type for format '%s'", fmt);
+    return -1;
 }
 
-static PyObject *
-_IntTupleFromSsizet(int len, Py_ssize_t *vals)
+static int
+value_error_int(const char *fmt)
 {
-    int i;
-    PyObject *o;
-    PyObject *intTuple;
+    PyErr_Format(PyExc_ValueError,
+        "memoryview: invalid value for format '%s'", fmt);
+    return -1;
+}
 
-    if (vals == NULL) {
-        Py_INCREF(Py_None);
-        return Py_None;
+static int
+fix_error_int(const char *fmt)
+{
+    assert(PyErr_Occurred());
+    if (PyErr_ExceptionMatches(PyExc_TypeError)) {
+        PyErr_Clear();
+        return type_error_int(fmt);
     }
-    intTuple = PyTuple_New(len);
-    if (!intTuple)
-        return NULL;
-    for (i=0; i<len; i++) {
-        o = PyLong_FromSsize_t(vals[i]);
-        if (!o) {
-            Py_DECREF(intTuple);
-            return NULL;
-        }
-        PyTuple_SET_ITEM(intTuple, i, o);
+    else if (PyErr_ExceptionMatches(PyExc_OverflowError) ||
+             PyErr_ExceptionMatches(PyExc_ValueError)) {
+        PyErr_Clear();
+        return value_error_int(fmt);
     }
-    return intTuple;
+
+    return -1;
 }
 
-static PyObject *
-memory_shape_get(PyMemoryViewObject *self)
+/* Accept integer objects or objects with an __index__() method. */
+static long
+pylong_as_ld(PyObject *item)
 {
-    CHECK_RELEASED(self);
-    return _IntTupleFromSsizet(self->view.ndim, self->view.shape);
+    PyObject *tmp;
+    long ld;
+
+    tmp = PyNumber_Index(item);
+    if (tmp == NULL)
+        return -1;
+
+    ld = PyLong_AsLong(tmp);
+    Py_DECREF(tmp);
+    return ld;
 }
 
-static PyObject *
-memory_strides_get(PyMemoryViewObject *self)
+static unsigned long
+pylong_as_lu(PyObject *item)
 {
-    CHECK_RELEASED(self);
-    return _IntTupleFromSsizet(self->view.ndim, self->view.strides);
+    PyObject *tmp;
+    unsigned long lu;
+
+    tmp = PyNumber_Index(item);
+    if (tmp == NULL)
+        return (unsigned long)-1;
+
+    lu = PyLong_AsUnsignedLong(tmp);
+    Py_DECREF(tmp);
+    return lu;
 }
 
-static PyObject *
-memory_suboffsets_get(PyMemoryViewObject *self)
+#ifdef HAVE_LONG_LONG
+static PY_LONG_LONG
+pylong_as_lld(PyObject *item)
 {
-    CHECK_RELEASED(self);
-    return _IntTupleFromSsizet(self->view.ndim, self->view.suboffsets);
+    PyObject *tmp;
+    PY_LONG_LONG lld;
+
+    tmp = PyNumber_Index(item);
+    if (tmp == NULL)
+        return -1;
+
+    lld = PyLong_AsLongLong(tmp);
+    Py_DECREF(tmp);
+    return lld;
 }
 
-static PyObject *
-memory_readonly_get(PyMemoryViewObject *self)
+static unsigned PY_LONG_LONG
+pylong_as_llu(PyObject *item)
 {
-    CHECK_RELEASED(self);
-    return PyBool_FromLong(self->view.readonly);
+    PyObject *tmp;
+    unsigned PY_LONG_LONG llu;
+
+    tmp = PyNumber_Index(item);
+    if (tmp == NULL)
+        return (unsigned PY_LONG_LONG)-1;
+
+    llu = PyLong_AsUnsignedLongLong(tmp);
+    Py_DECREF(tmp);
+    return llu;
 }
+#endif
 
-static PyObject *
-memory_ndim_get(PyMemoryViewObject *self)
+static Py_ssize_t
+pylong_as_zd(PyObject *item)
 {
-    CHECK_RELEASED(self);
-    return PyLong_FromLong(self->view.ndim);
+    PyObject *tmp;
+    Py_ssize_t zd;
+
+    tmp = PyNumber_Index(item);
+    if (tmp == NULL)
+        return -1;
+
+    zd = PyLong_AsSsize_t(tmp);
+    Py_DECREF(tmp);
+    return zd;
 }
 
-static PyGetSetDef memory_getsetlist[] ={
-    {"format",                (getter)memory_format_get,      NULL, NULL},
-    {"itemsize",        (getter)memory_itemsize_get,    NULL, NULL},
-    {"shape",           (getter)memory_shape_get,       NULL, NULL},
-    {"strides",         (getter)memory_strides_get,     NULL, NULL},
-    {"suboffsets",      (getter)memory_suboffsets_get,  NULL, NULL},
-    {"readonly",        (getter)memory_readonly_get,    NULL, NULL},
-    {"ndim",            (getter)memory_ndim_get,        NULL, NULL},
-    {NULL, NULL, NULL, NULL},
-};
+static size_t
+pylong_as_zu(PyObject *item)
+{
+    PyObject *tmp;
+    size_t zu;
 
+    tmp = PyNumber_Index(item);
+    if (tmp == NULL)
+        return (size_t)-1;
 
-static PyObject *
-memory_tobytes(PyMemoryViewObject *mem, PyObject *noargs)
+    zu = PyLong_AsSize_t(tmp);
+    Py_DECREF(tmp);
+    return zu;
+}
+
+/* Timings with the ndarray from _testbuffer.c indicate that using the
+   struct module is around 15x slower than the two functions below. */
+
+#define UNPACK_SINGLE(dest, ptr, type) \
+    do {                                   \
+        type x;                            \
+        memcpy((char *)&x, ptr, sizeof x); \
+        dest = x;                          \
+    } while (0)
+
+/* Unpack a single item. 'fmt' can be any native format character in struct
+   module syntax. This function is very sensitive to small changes. With this
+   layout gcc automatically generates a fast jump table. */
+Py_LOCAL_INLINE(PyObject *)
+unpack_single(const char *ptr, const char *fmt)
 {
-    CHECK_RELEASED(mem);
-    return PyObject_CallFunctionObjArgs(
-            (PyObject *) &PyBytes_Type, mem, NULL);
+    unsigned PY_LONG_LONG llu;
+    unsigned long lu;
+    size_t zu;
+    PY_LONG_LONG lld;
+    long ld;
+    Py_ssize_t zd;
+    double d;
+    unsigned char uc;
+    void *p;
+
+    switch (fmt[0]) {
+
+    /* signed integers and fast path for 'B' */
+    case 'B': uc = *((unsigned char *)ptr); goto convert_uc;
+    case 'b': ld =   *((signed char *)ptr); goto convert_ld;
+    case 'h': UNPACK_SINGLE(ld, ptr, short); goto convert_ld;
+    case 'i': UNPACK_SINGLE(ld, ptr, int); goto convert_ld;
+    case 'l': UNPACK_SINGLE(ld, ptr, long); goto convert_ld;
+
+    /* boolean */
+    #ifdef HAVE_C99_BOOL
+    case '?': UNPACK_SINGLE(ld, ptr, _Bool); goto convert_bool;
+    #else
+    case '?': UNPACK_SINGLE(ld, ptr, char); goto convert_bool;
+    #endif
+
+    /* unsigned integers */
+    case 'H': UNPACK_SINGLE(lu, ptr, unsigned short); goto convert_lu;
+    case 'I': UNPACK_SINGLE(lu, ptr, unsigned int); goto convert_lu;
+    case 'L': UNPACK_SINGLE(lu, ptr, unsigned long); goto convert_lu;
+
+    /* native 64-bit */
+    #ifdef HAVE_LONG_LONG
+    case 'q': UNPACK_SINGLE(lld, ptr, PY_LONG_LONG); goto convert_lld;
+    case 'Q': UNPACK_SINGLE(llu, ptr, unsigned PY_LONG_LONG); goto convert_llu;
+    #endif
+
+    /* ssize_t and size_t */
+    case 'n': UNPACK_SINGLE(zd, ptr, Py_ssize_t); goto convert_zd;
+    case 'N': UNPACK_SINGLE(zu, ptr, size_t); goto convert_zu;
+
+    /* floats */
+    case 'f': UNPACK_SINGLE(d, ptr, float); goto convert_double;
+    case 'd': UNPACK_SINGLE(d, ptr, double); goto convert_double;
+
+    /* bytes object */
+    case 'c': goto convert_bytes;
+
+    /* pointer */
+    case 'P': UNPACK_SINGLE(p, ptr, void *); goto convert_pointer;
+
+    /* default */
+    default: goto err_format;
+    }
+
+convert_uc:
+    /* PyLong_FromUnsignedLong() is slower */
+    return PyLong_FromLong(uc);
+convert_ld:
+    return PyLong_FromLong(ld);
+convert_lu:
+    return PyLong_FromUnsignedLong(lu);
+convert_lld:
+    return PyLong_FromLongLong(lld);
+convert_llu:
+    return PyLong_FromUnsignedLongLong(llu);
+convert_zd:
+    return PyLong_FromSsize_t(zd);
+convert_zu:
+    return PyLong_FromSize_t(zu);
+convert_double:
+    return PyFloat_FromDouble(d);
+convert_bool:
+    return PyBool_FromLong(ld);
+convert_bytes:
+    return PyBytes_FromStringAndSize(ptr, 1);
+convert_pointer:
+    return PyLong_FromVoidPtr(p);
+err_format:
+    PyErr_Format(PyExc_NotImplementedError,
+        "memoryview: format %s not supported", fmt);
+    return NULL;
 }
 
-/* TODO: rewrite this function using the struct module to unpack
-   each buffer item */
+#define PACK_SINGLE(ptr, src, type) \
+    do {                                     \
+        type x;                              \
+        x = (type)src;                       \
+        memcpy(ptr, (char *)&x, sizeof x);   \
+    } while (0)
+
+/* Pack a single item. 'fmt' can be any native format character in
+   struct module syntax. */
+static int
+pack_single(char *ptr, PyObject *item, const char *fmt)
+{
+    unsigned PY_LONG_LONG llu;
+    unsigned long lu;
+    size_t zu;
+    PY_LONG_LONG lld;
+    long ld;
+    Py_ssize_t zd;
+    double d;
+    void *p;
+
+    switch (fmt[0]) {
+    /* signed integers */
+    case 'b': case 'h': case 'i': case 'l':
+        ld = pylong_as_ld(item);
+        if (ld == -1 && PyErr_Occurred())
+            goto err_occurred;
+        switch (fmt[0]) {
+        case 'b':
+            if (ld < SCHAR_MIN || ld > SCHAR_MAX) goto err_range;
+            *((signed char *)ptr) = (signed char)ld; break;
+        case 'h':
+            if (ld < SHRT_MIN || ld > SHRT_MAX) goto err_range;
+            PACK_SINGLE(ptr, ld, short); break;
+        case 'i':
+            if (ld < INT_MIN || ld > INT_MAX) goto err_range;
+            PACK_SINGLE(ptr, ld, int); break;
+        default: /* 'l' */
+            PACK_SINGLE(ptr, ld, long); break;
+        }
+        break;
+
+    /* unsigned integers */
+    case 'B': case 'H': case 'I': case 'L':
+        lu = pylong_as_lu(item);
+        if (lu == (unsigned long)-1 && PyErr_Occurred())
+            goto err_occurred;
+        switch (fmt[0]) {
+        case 'B':
+            if (lu > UCHAR_MAX) goto err_range;
+            *((unsigned char *)ptr) = (unsigned char)lu; break;
+        case 'H':
+            if (lu > USHRT_MAX) goto err_range;
+            PACK_SINGLE(ptr, lu, unsigned short); break;
+        case 'I':
+            if (lu > UINT_MAX) goto err_range;
+            PACK_SINGLE(ptr, lu, unsigned int); break;
+        default: /* 'L' */
+            PACK_SINGLE(ptr, lu, unsigned long); break;
+        }
+        break;
+
+    /* native 64-bit */
+    #ifdef HAVE_LONG_LONG
+    case 'q':
+        lld = pylong_as_lld(item);
+        if (lld == -1 && PyErr_Occurred())
+            goto err_occurred;
+        PACK_SINGLE(ptr, lld, PY_LONG_LONG);
+        break;
+    case 'Q':
+        llu = pylong_as_llu(item);
+        if (llu == (unsigned PY_LONG_LONG)-1 && PyErr_Occurred())
+            goto err_occurred;
+        PACK_SINGLE(ptr, llu, unsigned PY_LONG_LONG);
+        break;
+    #endif
+
+    /* ssize_t and size_t */
+    case 'n':
+        zd = pylong_as_zd(item);
+        if (zd == -1 && PyErr_Occurred())
+            goto err_occurred;
+        PACK_SINGLE(ptr, zd, Py_ssize_t);
+        break;
+    case 'N':
+        zu = pylong_as_zu(item);
+        if (zu == (size_t)-1 && PyErr_Occurred())
+            goto err_occurred;
+        PACK_SINGLE(ptr, zu, size_t);
+        break;
+
+    /* floats */
+    case 'f': case 'd':
+        d = PyFloat_AsDouble(item);
+        if (d == -1.0 && PyErr_Occurred())
+            goto err_occurred;
+        if (fmt[0] == 'f') {
+            PACK_SINGLE(ptr, d, float);
+        }
+        else {
+            PACK_SINGLE(ptr, d, double);
+        }
+        break;
+
+    /* bool */
+    case '?':
+        ld = PyObject_IsTrue(item);
+        if (ld < 0)
+            return -1; /* preserve original error */
+    #ifdef HAVE_C99_BOOL
+        PACK_SINGLE(ptr, ld, _Bool);
+    #else
+        PACK_SINGLE(ptr, ld, char);
+    #endif
+         break;
+
+    /* bytes object */
+    case 'c':
+        if (!PyBytes_Check(item))
+            return type_error_int(fmt);
+        if (PyBytes_GET_SIZE(item) != 1)
+            return value_error_int(fmt);
+        *ptr = PyBytes_AS_STRING(item)[0];
+        break;
 
+    /* pointer */
+    case 'P':
+        p = PyLong_AsVoidPtr(item);
+        if (p == NULL && PyErr_Occurred())
+            goto err_occurred;
+        PACK_SINGLE(ptr, p, void *);
+        break;
+
+    /* default */
+    default: goto err_format;
+    }
+
+    return 0;
+
+err_occurred:
+    return fix_error_int(fmt);
+err_range:
+    return value_error_int(fmt);
+err_format:
+    PyErr_Format(PyExc_NotImplementedError,
+        "memoryview: format %s not supported", fmt);
+    return -1;
+}
+
+
+/****************************************************************************/
+/*                              Representations                             */
+/****************************************************************************/
+
+/* allow explicit form of native format */
+Py_LOCAL_INLINE(const char *)
+adjust_fmt(const Py_buffer *view)
+{
+    const char *fmt;
+
+    fmt = (view->format[0] == '@') ? view->format+1 : view->format;
+    if (fmt[0] && fmt[1] == '\0')
+        return fmt;
+
+    PyErr_Format(PyExc_NotImplementedError,
+        "memoryview: unsupported format %s", view->format);
+    return NULL;
+}
+
+/* Base case for multi-dimensional unpacking. Assumption: ndim == 1. */
 static PyObject *
-memory_tolist(PyMemoryViewObject *mem, PyObject *noargs)
+tolist_base(const char *ptr, const Py_ssize_t *shape,
+            const Py_ssize_t *strides, const Py_ssize_t *suboffsets,
+            const char *fmt)
 {
-    Py_buffer *view = &(mem->view);
+    PyObject *lst, *item;
     Py_ssize_t i;
-    PyObject *res, *item;
-    char *buf;
 
-    CHECK_RELEASED(mem);
-    if (strcmp(view->format, "B") || view->itemsize != 1) {
-        PyErr_SetString(PyExc_NotImplementedError, 
-                "tolist() only supports byte views");
-        return NULL;
-    }
-    if (view->ndim != 1) {
-        PyErr_SetString(PyExc_NotImplementedError, 
-                "tolist() only supports one-dimensional objects");
-        return NULL;
-    }
-    res = PyList_New(view->len);
-    if (res == NULL)
+    lst = PyList_New(shape[0]);
+    if (lst == NULL)
         return NULL;
-    buf = view->buf;
-    for (i = 0; i < view->len; i++) {
-        item = PyLong_FromUnsignedLong((unsigned char) *buf);
+
+    for (i = 0; i < shape[0]; ptr+=strides[0], i++) {
+        const char *xptr = ADJUST_PTR(ptr, suboffsets);
+        item = unpack_single(xptr, fmt);
         if (item == NULL) {
-            Py_DECREF(res);
+            Py_DECREF(lst);
             return NULL;
         }
-        PyList_SET_ITEM(res, i, item);
-        buf++;
+        PyList_SET_ITEM(lst, i, item);
     }
-    return res;
+
+    return lst;
 }
 
-static void
-do_release(PyMemoryViewObject *self)
+/* Unpack a multi-dimensional array into a nested list.
+   Assumption: ndim >= 1. */
+static PyObject *
+tolist_rec(const char *ptr, Py_ssize_t ndim, const Py_ssize_t *shape,
+           const Py_ssize_t *strides, const Py_ssize_t *suboffsets,
+           const char *fmt)
 {
-    if (self->view.obj != NULL) {
-        PyBuffer_Release(&(self->view));
+    PyObject *lst, *item;
+    Py_ssize_t i;
+
+    assert(ndim >= 1);
+    assert(shape != NULL);
+    assert(strides != NULL);
+
+    if (ndim == 1)
+        return tolist_base(ptr, shape, strides, suboffsets, fmt);
+
+    lst = PyList_New(shape[0]);
+    if (lst == NULL)
+        return NULL;
+
+    for (i = 0; i < shape[0]; ptr+=strides[0], i++) {
+        const char *xptr = ADJUST_PTR(ptr, suboffsets);
+        item = tolist_rec(xptr, ndim-1, shape+1,
+                          strides+1, suboffsets ? suboffsets+1 : NULL,
+                          fmt);
+        if (item == NULL) {
+            Py_DECREF(lst);
+            return NULL;
+        }
+        PyList_SET_ITEM(lst, i, item);
     }
-    self->view.obj = NULL;
-    self->view.buf = NULL;
+
+    return lst;
 }
 
+/* Return a list representation of the memoryview. Currently only buffers
+   with native format strings are supported. */
 static PyObject *
-memory_enter(PyObject *self, PyObject *args)
+memory_tolist(PyMemoryViewObject *mv, PyObject *noargs)
 {
-    CHECK_RELEASED(self);
-    Py_INCREF(self);
-    return self;
+    const Py_buffer *view = &(mv->view);
+    const char *fmt;
+
+    CHECK_RELEASED(mv);
+
+    fmt = adjust_fmt(view);
+    if (fmt == NULL)
+        return NULL;
+    if (view->ndim == 0) {
+        return unpack_single(view->buf, fmt);
+    }
+    else if (view->ndim == 1) {
+        return tolist_base(view->buf, view->shape,
+                           view->strides, view->suboffsets,
+                           fmt);
+    }
+    else {
+        return tolist_rec(view->buf, view->ndim, view->shape,
+                          view->strides, view->suboffsets,
+                          fmt);
+    }
 }
 
 static PyObject *
-memory_exit(PyObject *self, PyObject *args)
+memory_tobytes(PyMemoryViewObject *self, PyObject *dummy)
 {
-    do_release((PyMemoryViewObject *) self);
-    Py_RETURN_NONE;
-}
+    Py_buffer *src = VIEW_ADDR(self);
+    PyObject *bytes = NULL;
 
-static PyMethodDef memory_methods[] = {
-    {"release", memory_exit, METH_NOARGS},
-    {"tobytes", (PyCFunction)memory_tobytes, METH_NOARGS, NULL},
-    {"tolist", (PyCFunction)memory_tolist, METH_NOARGS, NULL},
-    {"__enter__", memory_enter, METH_NOARGS},
-    {"__exit__", memory_exit, METH_VARARGS},
-    {NULL,          NULL}           /* sentinel */
-};
+    CHECK_RELEASED(self);
 
+    if (MV_C_CONTIGUOUS(self->flags)) {
+        return PyBytes_FromStringAndSize(src->buf, src->len);
+    }
 
-static void
-memory_dealloc(PyMemoryViewObject *self)
-{
-    _PyObject_GC_UNTRACK(self);
-    do_release(self);
-    PyObject_GC_Del(self);
+    bytes = PyBytes_FromStringAndSize(NULL, src->len);
+    if (bytes == NULL)
+        return NULL;
+
+    if (buffer_to_c_contiguous(PyBytes_AS_STRING(bytes), src) < 0) {
+        Py_DECREF(bytes);
+        return NULL;
+    }
+
+    return bytes;
 }
 
 static PyObject *
 memory_repr(PyMemoryViewObject *self)
 {
-    if (IS_RELEASED(self))
+    if (self->flags & _Py_MEMORYVIEW_RELEASED)
         return PyUnicode_FromFormat("<released memory at %p>", self);
     else
         return PyUnicode_FromFormat("<memory at %p>", self);
 }
 
-static Py_hash_t
-memory_hash(PyMemoryViewObject *self)
+
+/**************************************************************************/
+/*                          Indexing and slicing                          */
+/**************************************************************************/
+
+/* Get the pointer to the item at index. */
+static char *
+ptr_from_index(Py_buffer *view, Py_ssize_t index)
 {
-    if (self->hash == -1) {
-        Py_buffer *view = &self->view;
-        CHECK_RELEASED_INT(self);
-        if (view->ndim > 1) {
-            PyErr_SetString(PyExc_NotImplementedError,
-                            "can't hash multi-dimensional memoryview object");
-            return -1;
-        }
-        if (view->strides && view->strides[0] != view->itemsize) {
-            PyErr_SetString(PyExc_NotImplementedError,
-                            "can't hash strided memoryview object");
-            return -1;
-        }
-        if (!view->readonly) {
-            PyErr_SetString(PyExc_ValueError,
-                            "can't hash writable memoryview object");
-            return -1;
-        }
-        if (view->obj != NULL && PyObject_Hash(view->obj) == -1) {
-            /* Keep the original error message */
-            return -1;
-        }
-        /* Can't fail */
-        self->hash = _Py_HashBytes((unsigned char *) view->buf, view->len);
+    char *ptr;
+    Py_ssize_t nitems; /* items in the first dimension */
+
+    assert(view->shape);
+    assert(view->strides);
+
+    nitems = view->shape[0];
+    if (index < 0) {
+        index += nitems;
+    }
+    if (index < 0 || index >= nitems) {
+        PyErr_SetString(PyExc_IndexError, "index out of bounds");
+        return NULL;
     }
-    return self->hash;
-}
 
-/* Sequence methods */
-static Py_ssize_t
-memory_length(PyMemoryViewObject *self)
-{
-    CHECK_RELEASED_INT(self);
-    return get_shape0(&self->view);
+    ptr = (char *)view->buf;
+    ptr += view->strides[0] * index;
+
+    ptr = ADJUST_PTR(ptr, view->suboffsets);
+
+    return ptr;
 }
 
-/* Alternate version of memory_subcript that only accepts indices.
-   Used by PySeqIter_New().
-*/
+/* Return the item at index. In a one-dimensional view, this is an object
+   with the type specified by view->format. Otherwise, the item is a sub-view.
+   The function is used in memory_subscript() and memory_as_sequence. */
 static PyObject *
-memory_item(PyMemoryViewObject *self, Py_ssize_t result)
+memory_item(PyMemoryViewObject *self, Py_ssize_t index)
 {
     Py_buffer *view = &(self->view);
+    const char *fmt;
 
     CHECK_RELEASED(self);
+
+    fmt = adjust_fmt(view);
+    if (fmt == NULL)
+        return NULL;
+
     if (view->ndim == 0) {
-        PyErr_SetString(PyExc_IndexError,
-                        "invalid indexing of 0-dim memory");
+        PyErr_SetString(PyExc_TypeError, "invalid indexing of 0-dim memory");
         return NULL;
     }
     if (view->ndim == 1) {
-        /* Return a bytes object */
-        char *ptr;
-        ptr = (char *)view->buf;
-        if (result < 0) {
-            result += get_shape0(view);
-        }
-        if ((result < 0) || (result >= get_shape0(view))) {
-            PyErr_SetString(PyExc_IndexError,
-                                "index out of bounds");
+        char *ptr = ptr_from_index(view, index);
+        if (ptr == NULL)
             return NULL;
-        }
-        if (view->strides == NULL)
-            ptr += view->itemsize * result;
-        else
-            ptr += view->strides[0] * result;
-        if (view->suboffsets != NULL &&
-            view->suboffsets[0] >= 0) {
-            ptr = *((char **)ptr) + view->suboffsets[0];
-        }
-        return PyBytes_FromStringAndSize(ptr, view->itemsize);
-    } else {
-        /* Return a new memory-view object */
-        Py_buffer newview;
-        memset(&newview, 0, sizeof(newview));
-        /* XXX:  This needs to be fixed so it actually returns a sub-view */
-        return PyMemoryView_FromBuffer(&newview);
+        return unpack_single(ptr, fmt);
     }
+
+    PyErr_SetString(PyExc_NotImplementedError,
+        "multi-dimensional sub-views are not implemented");
+    return NULL;
 }
 
-/*
-  mem[obj] returns a bytes object holding the data for one element if
-           obj fully indexes the memory view or another memory-view object
-           if it does not.
+Py_LOCAL_INLINE(int)
+init_slice(Py_buffer *base, PyObject *key, int dim)
+{
+    Py_ssize_t start, stop, step, slicelength;
 
-           0-d memory-view objects can be referenced using ... or () but
-           not with anything else.
- */
+    if (PySlice_GetIndicesEx(key, base->shape[dim],
+                             &start, &stop, &step, &slicelength) < 0) {
+        return -1;
+    }
+
+
+    if (base->suboffsets == NULL || dim == 0) {
+    adjust_buf:
+        base->buf = (char *)base->buf + base->strides[dim] * start;
+    }
+    else {
+        Py_ssize_t n = dim-1;
+        while (n >= 0 && base->suboffsets[n] < 0)
+            n--;
+        if (n < 0)
+            goto adjust_buf; /* all suboffsets are negative */
+        base->suboffsets[n] = base->suboffsets[n] + base->strides[dim] * start;
+    }
+    base->shape[dim] = slicelength;
+    base->strides[dim] = base->strides[dim] * step;
+
+    return 0;
+}
+
+static int
+is_multislice(PyObject *key)
+{
+    Py_ssize_t size, i;
+
+    if (!PyTuple_Check(key))
+        return 0;
+    size = PyTuple_GET_SIZE(key);
+    if (size == 0)
+        return 0;
+
+    for (i = 0; i < size; i++) {
+        PyObject *x = PyTuple_GET_ITEM(key, i);
+        if (!PySlice_Check(x))
+            return 0;
+    }
+    return 1;
+}
+
+/* mv[obj] returns an object holding the data for one element if obj
+   fully indexes the memoryview or another memoryview object if it
+   does not.
+
+   0-d memoryview objects can be referenced using mv[...] or mv[()]
+   but not with anything else. */
 static PyObject *
 memory_subscript(PyMemoryViewObject *self, PyObject *key)
 {
@@ -611,247 +2030,567 @@ memory_subscript(PyMemoryViewObject *self, PyObject *key)
     view = &(self->view);
     
     CHECK_RELEASED(self);
+
     if (view->ndim == 0) {
-        if (key == Py_Ellipsis ||
-            (PyTuple_Check(key) && PyTuple_GET_SIZE(key)==0)) {
+        if (PyTuple_Check(key) && PyTuple_GET_SIZE(key) == 0) {
+            const char *fmt = adjust_fmt(view);
+            if (fmt == NULL)
+                return NULL;
+            return unpack_single(view->buf, fmt);
+        }
+        else if (key == Py_Ellipsis) {
             Py_INCREF(self);
             return (PyObject *)self;
         }
         else {
-            PyErr_SetString(PyExc_IndexError,
-                                "invalid indexing of 0-dim memory");
+            PyErr_SetString(PyExc_TypeError,
+                "invalid indexing of 0-dim memory");
             return NULL;
         }
     }
+
     if (PyIndex_Check(key)) {
-        Py_ssize_t result;
-        result = PyNumber_AsSsize_t(key, NULL);
-        if (result == -1 && PyErr_Occurred())
-                return NULL;
-        return memory_item(self, result);
+        Py_ssize_t index;
+        index = PyNumber_AsSsize_t(key, PyExc_IndexError);
+        if (index == -1 && PyErr_Occurred())
+            return NULL;
+        return memory_item(self, index);
     }
     else if (PySlice_Check(key)) {
-        Py_ssize_t start, stop, step, slicelength;
+        PyMemoryViewObject *sliced;
 
-        if (PySlice_GetIndicesEx(key, get_shape0(view),
-                                 &start, &stop, &step, &slicelength) < 0) {
+        sliced = (PyMemoryViewObject *)mbuf_add_view(self->mbuf, view);
+        if (sliced == NULL)
+            return NULL;
+
+        if (init_slice(&sliced->view, key, 0) < 0) {
+            Py_DECREF(sliced);
             return NULL;
         }
-    
-        if (step == 1 && view->ndim == 1) {
-            Py_buffer newview;
-            void *newbuf = (char *) view->buf
-                                    + start * view->itemsize;
-            int newflags = view->readonly
-                    ? PyBUF_CONTIG_RO : PyBUF_CONTIG;
-    
-            /* XXX There should be an API to create a subbuffer */
-            if (view->obj != NULL) {
-                if (PyObject_GetBuffer(view->obj, &newview, newflags) == -1)
-                    return NULL;
-            }
-            else {
-                newview = *view;
-            }
-            newview.buf = newbuf;
-            newview.len = slicelength * newview.itemsize;
-            newview.format = view->format;
-            newview.shape = &(newview.smalltable[0]);
-            newview.shape[0] = slicelength;
-            newview.strides = &(newview.itemsize);
-            return PyMemoryView_FromBuffer(&newview);
-        }
-        PyErr_SetNone(PyExc_NotImplementedError);
+        init_len(&sliced->view);
+        init_flags(sliced);
+
+        return (PyObject *)sliced;
+    }
+    else if (is_multislice(key)) {
+        PyErr_SetString(PyExc_NotImplementedError,
+            "multi-dimensional slicing is not implemented");
         return NULL;
     }
-    PyErr_Format(PyExc_TypeError,
-        "cannot index memory using \"%.200s\"", 
-        key->ob_type->tp_name);
+
+    PyErr_SetString(PyExc_TypeError, "memoryview: invalid slice key");
     return NULL;
 }
 
-
-/* Need to support assigning memory if we can */
 static int
 memory_ass_sub(PyMemoryViewObject *self, PyObject *key, PyObject *value)
 {
-    Py_ssize_t start, len, bytelen;
-    Py_buffer srcview;
     Py_buffer *view = &(self->view);
-    char *srcbuf, *destbuf;
+    Py_buffer src;
+    const char *fmt;
+    char *ptr;
 
     CHECK_RELEASED_INT(self);
+
+    fmt = adjust_fmt(view);
+    if (fmt == NULL)
+        return -1;
+
     if (view->readonly) {
-        PyErr_SetString(PyExc_TypeError,
-            "cannot modify read-only memory");
+        PyErr_SetString(PyExc_TypeError, "cannot modify read-only memory");
         return -1;
     }
     if (value == NULL) {
-        PyErr_SetString(PyExc_TypeError,
-                        "cannot delete memory");
+        PyErr_SetString(PyExc_TypeError, "cannot delete memory");
         return -1;
     }
-    if (view->ndim != 1) {
-        PyErr_SetNone(PyExc_NotImplementedError);
-        return -1;
-    }
-    if (PyIndex_Check(key)) {
-        start = PyNumber_AsSsize_t(key, NULL);
-        if (start == -1 && PyErr_Occurred())
-            return -1;
-        if (start < 0) {
-            start += get_shape0(view);
+    if (view->ndim == 0) {
+        if (key == Py_Ellipsis ||
+            (PyTuple_Check(key) && PyTuple_GET_SIZE(key)==0)) {
+            ptr = (char *)view->buf;
+            return pack_single(ptr, value, fmt);
         }
-        if ((start < 0) || (start >= get_shape0(view))) {
-            PyErr_SetString(PyExc_IndexError,
-                            "index out of bounds");
+        else {
+            PyErr_SetString(PyExc_TypeError,
+                "invalid indexing of 0-dim memory");
             return -1;
         }
-        len = 1;
     }
-    else if (PySlice_Check(key)) {
-        Py_ssize_t stop, step;
+    if (view->ndim != 1) {
+        PyErr_SetString(PyExc_NotImplementedError,
+            "memoryview assignments are currently restricted to ndim = 1");
+        return -1;
+    }
 
-        if (PySlice_GetIndicesEx(key, get_shape0(view),
-                         &start, &stop, &step, &len) < 0) {
+    if (PyIndex_Check(key)) {
+        Py_ssize_t index = PyNumber_AsSsize_t(key, PyExc_IndexError);
+        if (index == -1 && PyErr_Occurred())
             return -1;
-        }
-        if (step != 1) {
-            PyErr_SetNone(PyExc_NotImplementedError);
+        ptr = ptr_from_index(view, index);
+        if (ptr == NULL)
             return -1;
+        return pack_single(ptr, value, fmt);
+    }
+    /* one-dimensional: fast path */
+    if (PySlice_Check(key) && view->ndim == 1) {
+        Py_buffer dest; /* sliced view */
+        Py_ssize_t arrays[3];
+        int ret = -1;
+
+        /* rvalue must be an exporter */
+        if (PyObject_GetBuffer(value, &src, PyBUF_FULL_RO) < 0)
+            return ret;
+
+        dest = *view;
+        dest.shape = &arrays[0]; dest.shape[0] = view->shape[0];
+        dest.strides = &arrays[1]; dest.strides[0] = view->strides[0];
+        if (view->suboffsets) {
+            dest.suboffsets = &arrays[2]; dest.suboffsets[0] = view->suboffsets[0];
         }
+
+        if (init_slice(&dest, key, 0) < 0)
+            goto end_block;
+        dest.len = dest.shape[0] * dest.itemsize;
+
+        ret = copy_single(&dest, &src);
+
+    end_block:
+        PyBuffer_Release(&src);
+        return ret;
     }
-    else {
-        PyErr_Format(PyExc_TypeError,
-            "cannot index memory using \"%.200s\"", 
-            key->ob_type->tp_name);
+    else if (PySlice_Check(key) || is_multislice(key)) {
+        /* Call memory_subscript() to produce a sliced lvalue, then copy
+           rvalue into lvalue. This is already implemented in _testbuffer.c. */
+        PyErr_SetString(PyExc_NotImplementedError,
+            "memoryview slice assignments are currently restricted "
+            "to ndim = 1");
         return -1;
     }
-    if (PyObject_GetBuffer(value, &srcview, PyBUF_CONTIG_RO) == -1) {
-        return -1;
+
+    PyErr_SetString(PyExc_TypeError, "memoryview: invalid slice key");
+    return -1;
+}
+
+static Py_ssize_t
+memory_length(PyMemoryViewObject *self)
+{
+    CHECK_RELEASED_INT(self);
+    return self->view.ndim == 0 ? 1 : self->view.shape[0];
+}
+
+/* As mapping */
+static PyMappingMethods memory_as_mapping = {
+    (lenfunc)memory_length,               /* mp_length */
+    (binaryfunc)memory_subscript,         /* mp_subscript */
+    (objobjargproc)memory_ass_sub,        /* mp_ass_subscript */
+};
+
+/* As sequence */
+static PySequenceMethods memory_as_sequence = {
+        0,                                /* sq_length */
+        0,                                /* sq_concat */
+        0,                                /* sq_repeat */
+        (ssizeargfunc)memory_item,        /* sq_item */
+};
+
+
+/**************************************************************************/
+/*                             Comparisons                                */
+/**************************************************************************/
+
+#define CMP_SINGLE(p, q, type) \
+    do {                                 \
+        type x;                          \
+        type y;                          \
+        memcpy((char *)&x, p, sizeof x); \
+        memcpy((char *)&y, q, sizeof y); \
+        equal = (x == y);                \
+    } while (0)
+
+Py_LOCAL_INLINE(int)
+unpack_cmp(const char *p, const char *q, const char *fmt)
+{
+    int equal;
+
+    switch (fmt[0]) {
+
+    /* signed integers and fast path for 'B' */
+    case 'B': return *((unsigned char *)p) == *((unsigned char *)q);
+    case 'b': return *((signed char *)p) == *((signed char *)q);
+    case 'h': CMP_SINGLE(p, q, short); return equal;
+    case 'i': CMP_SINGLE(p, q, int); return equal;
+    case 'l': CMP_SINGLE(p, q, long); return equal;
+
+    /* boolean */
+    #ifdef HAVE_C99_BOOL
+    case '?': CMP_SINGLE(p, q, _Bool); return equal;
+    #else
+    case '?': CMP_SINGLE(p, q, char); return equal;
+    #endif
+
+    /* unsigned integers */
+    case 'H': CMP_SINGLE(p, q, unsigned short); return equal;
+    case 'I': CMP_SINGLE(p, q, unsigned int); return equal;
+    case 'L': CMP_SINGLE(p, q, unsigned long); return equal;
+
+    /* native 64-bit */
+    #ifdef HAVE_LONG_LONG
+    case 'q': CMP_SINGLE(p, q, PY_LONG_LONG); return equal;
+    case 'Q': CMP_SINGLE(p, q, unsigned PY_LONG_LONG); return equal;
+    #endif
+
+    /* ssize_t and size_t */
+    case 'n': CMP_SINGLE(p, q, Py_ssize_t); return equal;
+    case 'N': CMP_SINGLE(p, q, size_t); return equal;
+
+    /* floats */
+    /* XXX DBL_EPSILON? */
+    case 'f': CMP_SINGLE(p, q, float); return equal;
+    case 'd': CMP_SINGLE(p, q, double); return equal;
+
+    /* bytes object */
+    case 'c': return *p == *q;
+
+    /* pointer */
+    case 'P': CMP_SINGLE(p, q, void *); return equal;
+
+    /* Py_NotImplemented */
+    default: return -1;
     }
-    /* XXX should we allow assignment of different item sizes
-       as long as the byte length is the same?
-       (e.g. assign 2 shorts to a 4-byte slice) */
-    if (srcview.itemsize != view->itemsize) {
-        PyErr_Format(PyExc_TypeError,
-            "mismatching item sizes for \"%.200s\" and \"%.200s\"", 
-            view->obj->ob_type->tp_name, srcview.obj->ob_type->tp_name);
-        goto _error;
-    }
-    bytelen = len * view->itemsize;
-    if (bytelen != srcview.len) {
-        PyErr_SetString(PyExc_ValueError,
-            "cannot modify size of memoryview object");
-        goto _error;
-    }
-    /* Do the actual copy */
-    destbuf = (char *) view->buf + start * view->itemsize;
-    srcbuf = (char *) srcview.buf;
-    if (destbuf + bytelen < srcbuf || srcbuf + bytelen < destbuf)
-        /* No overlapping */
-        memcpy(destbuf, srcbuf, bytelen);
-    else
-        memmove(destbuf, srcbuf, bytelen);
+}
 
-    PyBuffer_Release(&srcview);
-    return 0;
+/* Base case for recursive array comparisons. Assumption: ndim == 1. */
+static int
+cmp_base(const char *p, const char *q, const Py_ssize_t *shape,
+         const Py_ssize_t *pstrides, const Py_ssize_t *psuboffsets,
+         const Py_ssize_t *qstrides, const Py_ssize_t *qsuboffsets,
+         const char *fmt)
+{
+    Py_ssize_t i;
+    int equal;
+
+    for (i = 0; i < shape[0]; p+=pstrides[0], q+=qstrides[0], i++) {
+        const char *xp = ADJUST_PTR(p, psuboffsets);
+        const char *xq = ADJUST_PTR(q, qsuboffsets);
+        equal = unpack_cmp(xp, xq, fmt);
+        if (equal <= 0)
+            return equal;
+    }
 
-_error:
-    PyBuffer_Release(&srcview);
-    return -1;
+    return 1;
+}
+
+/* Recursively compare two multi-dimensional arrays that have the same
+   logical structure. Assumption: ndim >= 1. */
+static int
+cmp_rec(const char *p, const char *q,
+        Py_ssize_t ndim, const Py_ssize_t *shape,
+        const Py_ssize_t *pstrides, const Py_ssize_t *psuboffsets,
+        const Py_ssize_t *qstrides, const Py_ssize_t *qsuboffsets,
+        const char *fmt)
+{
+    Py_ssize_t i;
+    int equal;
+
+    assert(ndim >= 1);
+    assert(shape != NULL);
+    assert(pstrides != NULL);
+    assert(qstrides != NULL);
+
+    if (ndim == 1) {
+        return cmp_base(p, q, shape,
+                        pstrides, psuboffsets,
+                        qstrides, qsuboffsets,
+                        fmt);
+    }
+
+    for (i = 0; i < shape[0]; p+=pstrides[0], q+=qstrides[0], i++) {
+        const char *xp = ADJUST_PTR(p, psuboffsets);
+        const char *xq = ADJUST_PTR(q, qsuboffsets);
+        equal = cmp_rec(xp, xq, ndim-1, shape+1,
+                        pstrides+1, psuboffsets ? psuboffsets+1 : NULL,
+                        qstrides+1, qsuboffsets ? qsuboffsets+1 : NULL,
+                        fmt);
+        if (equal <= 0)
+            return equal;
+    }
+
+    return 1;
 }
 
 static PyObject *
 memory_richcompare(PyObject *v, PyObject *w, int op)
 {
-    Py_buffer vv, ww;
-    int equal = 0;
     PyObject *res;
+    Py_buffer wbuf, *vv, *ww = NULL;
+    const char *vfmt, *wfmt;
+    int equal = -1; /* Py_NotImplemented */
 
-    vv.obj = NULL;
-    ww.obj = NULL;
     if (op != Py_EQ && op != Py_NE)
-        goto _notimpl;
-    if ((PyMemoryView_Check(v) && IS_RELEASED(v)) ||
-        (PyMemoryView_Check(w) && IS_RELEASED(w))) {
+        goto result; /* Py_NotImplemented */
+
+    assert(PyMemoryView_Check(v));
+    if (BASE_INACCESSIBLE(v)) {
         equal = (v == w);
-        goto _end;
+        goto result;
     }
-    if (PyObject_GetBuffer(v, &vv, PyBUF_CONTIG_RO) == -1) {
-        PyErr_Clear();
-        goto _notimpl;
+    vv = VIEW_ADDR(v);
+
+    if (PyMemoryView_Check(w)) {
+        if (BASE_INACCESSIBLE(w)) {
+            equal = (v == w);
+            goto result;
+        }
+        ww = VIEW_ADDR(w);
+    }
+    else {
+        if (PyObject_GetBuffer(w, &wbuf, PyBUF_FULL_RO) < 0) {
+            PyErr_Clear();
+            goto result; /* Py_NotImplemented */
+        }
+        ww = &wbuf;
     }
-    if (PyObject_GetBuffer(w, &ww, PyBUF_CONTIG_RO) == -1) {
+
+    vfmt = adjust_fmt(vv);
+    wfmt = adjust_fmt(ww);
+    if (vfmt == NULL || wfmt == NULL) {
         PyErr_Clear();
-        goto _notimpl;
+        goto result; /* Py_NotImplemented */
     }
 
-    if (vv.itemsize != ww.itemsize || vv.len != ww.len)
-        goto _end;
+    if (cmp_structure(vv, ww) < 0) {
+        PyErr_Clear();
+        equal = 0;
+        goto result;
+    }
 
-    equal = !memcmp(vv.buf, ww.buf, vv.len);
+    if (vv->ndim == 0) {
+        equal = unpack_cmp(vv->buf, ww->buf, vfmt);
+    }
+    else if (vv->ndim == 1) {
+        equal = cmp_base(vv->buf, ww->buf, vv->shape,
+                         vv->strides, vv->suboffsets,
+                         ww->strides, ww->suboffsets,
+                         vfmt);
+    }
+    else {
+        equal = cmp_rec(vv->buf, ww->buf, vv->ndim, vv->shape,
+                        vv->strides, vv->suboffsets,
+                        ww->strides, ww->suboffsets,
+                        vfmt);
+    }
 
-_end:
-    PyBuffer_Release(&vv);
-    PyBuffer_Release(&ww);
-    if ((equal && op == Py_EQ) || (!equal && op == Py_NE))
+result:
+    if (equal < 0)
+        res = Py_NotImplemented; 
+    else if ((equal && op == Py_EQ) || (!equal && op == Py_NE))
         res = Py_True;
     else
         res = Py_False;
+
+    if (ww == &wbuf)
+        PyBuffer_Release(ww);
     Py_INCREF(res);
     return res;
+}
+
+/**************************************************************************/
+/*                                Hash                                    */
+/**************************************************************************/
+
+static Py_hash_t
+memory_hash(PyMemoryViewObject *self)
+{
+    if (self->hash == -1) {
+        Py_buffer *view = &self->view;
+        char *mem = view->buf;
+
+        CHECK_RELEASED_INT(self);
 
-_notimpl:
-    PyBuffer_Release(&vv);
-    PyBuffer_Release(&ww);
-    Py_RETURN_NOTIMPLEMENTED;
+        if (!view->readonly) {
+            PyErr_SetString(PyExc_ValueError,
+                "cannot hash writable memoryview object");
+            return -1;
+        }
+        if (view->obj != NULL && PyObject_Hash(view->obj) == -1) {
+            /* Keep the original error message */
+            return -1;
+        }
+
+        if (!MV_C_CONTIGUOUS(self->flags)) {
+            mem = PyMem_Malloc(view->len);
+            if (mem == NULL) {
+                PyErr_NoMemory();
+                return -1;
+            }
+            if (buffer_to_c_contiguous(mem, view) < 0) {
+                PyMem_Free(mem);
+                return -1;
+            }
+        }
+
+        /* Can't fail */
+        self->hash = _Py_HashBytes((unsigned char *)mem, view->len);
+
+        if (mem != view->buf)
+            PyMem_Free(mem);
+    }
+
+    return self->hash;
 }
 
 
-static int
-memory_traverse(PyMemoryViewObject *self, visitproc visit, void *arg)
+/**************************************************************************/
+/*                                 getters                                */
+/**************************************************************************/
+
+static PyObject *
+_IntTupleFromSsizet(int len, Py_ssize_t *vals)
 {
-    if (self->view.obj != NULL)
-        Py_VISIT(self->view.obj);
-    return 0;
+    int i;
+    PyObject *o;
+    PyObject *intTuple;
+
+    if (vals == NULL)
+        return PyTuple_New(0);
+
+    intTuple = PyTuple_New(len);
+    if (!intTuple)
+        return NULL;
+    for (i=0; i<len; i++) {
+        o = PyLong_FromSsize_t(vals[i]);
+        if (!o) {
+            Py_DECREF(intTuple);
+            return NULL;
+        }
+        PyTuple_SET_ITEM(intTuple, i, o);
+    }
+    return intTuple;
 }
 
-static int
-memory_clear(PyMemoryViewObject *self)
+static PyObject *
+memory_obj_get(PyMemoryViewObject *self)
 {
-    PyBuffer_Release(&self->view);
-    return 0;
+    Py_buffer *view = &self->view;
+
+    CHECK_RELEASED(self);
+    if (view->obj == NULL) {
+        Py_RETURN_NONE;
+    }
+    Py_INCREF(view->obj);
+    return view->obj;
 }
 
+static PyObject *
+memory_nbytes_get(PyMemoryViewObject *self)
+{
+    CHECK_RELEASED(self);
+    return PyLong_FromSsize_t(self->view.len);
+}
 
-/* As mapping */
-static PyMappingMethods memory_as_mapping = {
-    (lenfunc)memory_length,               /* mp_length */
-    (binaryfunc)memory_subscript,         /* mp_subscript */
-    (objobjargproc)memory_ass_sub,        /* mp_ass_subscript */
-};
+static PyObject *
+memory_format_get(PyMemoryViewObject *self)
+{
+    CHECK_RELEASED(self);
+    return PyUnicode_FromString(self->view.format);
+}
 
-static PySequenceMethods memory_as_sequence = {
-        0,                                  /* sq_length */
-        0,                                  /* sq_concat */
-        0,                                  /* sq_repeat */
-        (ssizeargfunc)memory_item,          /* sq_item */
+static PyObject *
+memory_itemsize_get(PyMemoryViewObject *self)
+{
+    CHECK_RELEASED(self);
+    return PyLong_FromSsize_t(self->view.itemsize);
+}
+
+static PyObject *
+memory_shape_get(PyMemoryViewObject *self)
+{
+    CHECK_RELEASED(self);
+    return _IntTupleFromSsizet(self->view.ndim, self->view.shape);
+}
+
+static PyObject *
+memory_strides_get(PyMemoryViewObject *self)
+{
+    CHECK_RELEASED(self);
+    return _IntTupleFromSsizet(self->view.ndim, self->view.strides);
+}
+
+static PyObject *
+memory_suboffsets_get(PyMemoryViewObject *self)
+{
+    CHECK_RELEASED(self);
+    return _IntTupleFromSsizet(self->view.ndim, self->view.suboffsets);
+}
+
+static PyObject *
+memory_readonly_get(PyMemoryViewObject *self)
+{
+    CHECK_RELEASED(self);
+    return PyBool_FromLong(self->view.readonly);
+}
+
+static PyObject *
+memory_ndim_get(PyMemoryViewObject *self)
+{
+    CHECK_RELEASED(self);
+    return PyLong_FromLong(self->view.ndim);
+}
+
+static PyObject *
+memory_c_contiguous(PyMemoryViewObject *self, PyObject *dummy)
+{
+    CHECK_RELEASED(self);
+    return PyBool_FromLong(MV_C_CONTIGUOUS(self->flags));
+}
+
+static PyObject *
+memory_f_contiguous(PyMemoryViewObject *self, PyObject *dummy)
+{
+    CHECK_RELEASED(self);
+    return PyBool_FromLong(MV_F_CONTIGUOUS(self->flags));
+}
+
+static PyObject *
+memory_contiguous(PyMemoryViewObject *self, PyObject *dummy)
+{
+    CHECK_RELEASED(self);
+    return PyBool_FromLong(MV_ANY_CONTIGUOUS(self->flags));
+}
+
+static PyGetSetDef memory_getsetlist[] = {
+    {"obj",             (getter)memory_obj_get,        NULL, NULL},
+    {"nbytes",          (getter)memory_nbytes_get,     NULL, NULL},
+    {"readonly",        (getter)memory_readonly_get,   NULL, NULL},
+    {"itemsize",        (getter)memory_itemsize_get,   NULL, NULL},
+    {"format",          (getter)memory_format_get,     NULL, NULL},
+    {"ndim",            (getter)memory_ndim_get,       NULL, NULL},
+    {"shape",           (getter)memory_shape_get,      NULL, NULL},
+    {"strides",         (getter)memory_strides_get,    NULL, NULL},
+    {"suboffsets",      (getter)memory_suboffsets_get, NULL, NULL},
+    {"c_contiguous",    (getter)memory_c_contiguous,   NULL, NULL},
+    {"f_contiguous",    (getter)memory_f_contiguous,   NULL, NULL},
+    {"contiguous",      (getter)memory_contiguous,     NULL, NULL},
+    {NULL, NULL, NULL, NULL},
 };
 
-/* Buffer methods */
 
-static PyBufferProcs memory_as_buffer = {
-    (getbufferproc)memory_getbuf,         /* bf_getbuffer */
-    (releasebufferproc)memory_releasebuf, /* bf_releasebuffer */
+static PyMethodDef memory_methods[] = {
+    {"release",     (PyCFunction)memory_release, METH_NOARGS},
+    {"tobytes",     (PyCFunction)memory_tobytes, METH_NOARGS, NULL},
+    {"tolist",      (PyCFunction)memory_tolist, METH_NOARGS, NULL},
+    {"cast",        (PyCFunction)memory_cast, METH_VARARGS|METH_KEYWORDS, NULL},
+    {"__enter__",   memory_enter, METH_NOARGS},
+    {"__exit__",    memory_exit, METH_VARARGS},
+    {NULL,          NULL}
 };
 
 
 PyTypeObject PyMemoryView_Type = {
     PyVarObject_HEAD_INIT(&PyType_Type, 0)
-    "memoryview",
-    sizeof(PyMemoryViewObject),
-    0,
+    "memoryview",                             /* tp_name */
+    offsetof(PyMemoryViewObject, ob_array),   /* tp_basicsize */
+    sizeof(Py_ssize_t),                       /* tp_itemsize */
     (destructor)memory_dealloc,               /* tp_dealloc */
     0,                                        /* tp_print */
     0,                                        /* tp_getattr */
diff --git a/Objects/object.c b/Objects/object.c
index 2665d2135f..70d320ca35 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -1650,6 +1650,9 @@ _Py_ReadyTypes(void)
     if (PyType_Ready(&PyProperty_Type) < 0)
         Py_FatalError("Can't initialize property type");
 
+    if (PyType_Ready(&_PyManagedBuffer_Type) < 0)
+        Py_FatalError("Can't initialize managed buffer type");
+
     if (PyType_Ready(&PyMemoryView_Type) < 0)
         Py_FatalError("Can't initialize memoryview type");
 
diff --git a/PCbuild/_testbuffer.vcproj b/PCbuild/_testbuffer.vcproj
new file mode 100644
index 0000000000..795ea27769
--- /dev/null
+++ b/PCbuild/_testbuffer.vcproj
@@ -0,0 +1,521 @@
+<?xml version="1.0" encoding="Windows-1252"?>

+<VisualStudioProject

+	ProjectType="Visual C++"

+	Version="9.00"

+	Name="_testbuffer"

+	ProjectGUID="{A2697BD3-28C1-4AEC-9106-8B748639FD16}"

+	RootNamespace="_testbuffer"

+	Keyword="Win32Proj"

+	TargetFrameworkVersion="196613"

+	>

+	<Platforms>

+		<Platform

+			Name="Win32"

+		/>

+		<Platform

+			Name="x64"

+		/>

+	</Platforms>

+	<ToolFiles>

+	</ToolFiles>

+	<Configurations>

+		<Configuration

+			Name="Debug|Win32"

+			ConfigurationType="2"

+			InheritedPropertySheets=".\pyd_d.vsprops"

+			CharacterSet="0"

+			>

+			<Tool

+				Name="VCPreBuildEventTool"

+			/>

+			<Tool

+				Name="VCCustomBuildTool"

+			/>

+			<Tool

+				Name="VCXMLDataGeneratorTool"

+			/>

+			<Tool

+				Name="VCWebServiceProxyGeneratorTool"

+			/>

+			<Tool

+				Name="VCMIDLTool"

+			/>

+			<Tool

+				Name="VCCLCompilerTool"

+			/>

+			<Tool

+				Name="VCManagedResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCPreLinkEventTool"

+			/>

+			<Tool

+				Name="VCLinkerTool"

+				BaseAddress="0x1e1F0000"

+			/>

+			<Tool

+				Name="VCALinkTool"

+			/>

+			<Tool

+				Name="VCManifestTool"

+			/>

+			<Tool

+				Name="VCXDCMakeTool"

+			/>

+			<Tool

+				Name="VCBscMakeTool"

+			/>

+			<Tool

+				Name="VCFxCopTool"

+			/>

+			<Tool

+				Name="VCAppVerifierTool"

+			/>

+			<Tool

+				Name="VCPostBuildEventTool"

+			/>

+		</Configuration>

+		<Configuration

+			Name="Debug|x64"

+			ConfigurationType="2"

+			InheritedPropertySheets=".\pyd_d.vsprops;.\x64.vsprops"

+			CharacterSet="0"

+			>

+			<Tool

+				Name="VCPreBuildEventTool"

+			/>

+			<Tool

+				Name="VCCustomBuildTool"

+			/>

+			<Tool

+				Name="VCXMLDataGeneratorTool"

+			/>

+			<Tool

+				Name="VCWebServiceProxyGeneratorTool"

+			/>

+			<Tool

+				Name="VCMIDLTool"

+				TargetEnvironment="3"

+			/>

+			<Tool

+				Name="VCCLCompilerTool"

+			/>

+			<Tool

+				Name="VCManagedResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCPreLinkEventTool"

+			/>

+			<Tool

+				Name="VCLinkerTool"

+				BaseAddress="0x1e1F0000"

+			/>

+			<Tool

+				Name="VCALinkTool"

+			/>

+			<Tool

+				Name="VCManifestTool"

+			/>

+			<Tool

+				Name="VCXDCMakeTool"

+			/>

+			<Tool

+				Name="VCBscMakeTool"

+			/>

+			<Tool

+				Name="VCFxCopTool"

+			/>

+			<Tool

+				Name="VCAppVerifierTool"

+			/>

+			<Tool

+				Name="VCPostBuildEventTool"

+			/>

+		</Configuration>

+		<Configuration

+			Name="Release|Win32"

+			ConfigurationType="2"

+			InheritedPropertySheets=".\pyd.vsprops"

+			CharacterSet="0"

+			WholeProgramOptimization="1"

+			>

+			<Tool

+				Name="VCPreBuildEventTool"

+			/>

+			<Tool

+				Name="VCCustomBuildTool"

+			/>

+			<Tool

+				Name="VCXMLDataGeneratorTool"

+			/>

+			<Tool

+				Name="VCWebServiceProxyGeneratorTool"

+			/>

+			<Tool

+				Name="VCMIDLTool"

+			/>

+			<Tool

+				Name="VCCLCompilerTool"

+			/>

+			<Tool

+				Name="VCManagedResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCPreLinkEventTool"

+			/>

+			<Tool

+				Name="VCLinkerTool"

+				BaseAddress="0x1e1F0000"

+			/>

+			<Tool

+				Name="VCALinkTool"

+			/>

+			<Tool

+				Name="VCManifestTool"

+			/>

+			<Tool

+				Name="VCXDCMakeTool"

+			/>

+			<Tool

+				Name="VCBscMakeTool"

+			/>

+			<Tool

+				Name="VCFxCopTool"

+			/>

+			<Tool

+				Name="VCAppVerifierTool"

+			/>

+			<Tool

+				Name="VCPostBuildEventTool"

+			/>

+		</Configuration>

+		<Configuration

+			Name="Release|x64"

+			ConfigurationType="2"

+			InheritedPropertySheets=".\pyd.vsprops;.\x64.vsprops"

+			CharacterSet="0"

+			WholeProgramOptimization="1"

+			>

+			<Tool

+				Name="VCPreBuildEventTool"

+			/>

+			<Tool

+				Name="VCCustomBuildTool"

+			/>

+			<Tool

+				Name="VCXMLDataGeneratorTool"

+			/>

+			<Tool

+				Name="VCWebServiceProxyGeneratorTool"

+			/>

+			<Tool

+				Name="VCMIDLTool"

+				TargetEnvironment="3"

+			/>

+			<Tool

+				Name="VCCLCompilerTool"

+			/>

+			<Tool

+				Name="VCManagedResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCPreLinkEventTool"

+			/>

+			<Tool

+				Name="VCLinkerTool"

+				BaseAddress="0x1e1F0000"

+			/>

+			<Tool

+				Name="VCALinkTool"

+			/>

+			<Tool

+				Name="VCManifestTool"

+			/>

+			<Tool

+				Name="VCXDCMakeTool"

+			/>

+			<Tool

+				Name="VCBscMakeTool"

+			/>

+			<Tool

+				Name="VCFxCopTool"

+			/>

+			<Tool

+				Name="VCAppVerifierTool"

+			/>

+			<Tool

+				Name="VCPostBuildEventTool"

+			/>

+		</Configuration>

+		<Configuration

+			Name="PGInstrument|Win32"

+			ConfigurationType="2"

+			InheritedPropertySheets=".\pyd.vsprops;.\pginstrument.vsprops"

+			CharacterSet="0"

+			WholeProgramOptimization="1"

+			>

+			<Tool

+				Name="VCPreBuildEventTool"

+			/>

+			<Tool

+				Name="VCCustomBuildTool"

+			/>

+			<Tool

+				Name="VCXMLDataGeneratorTool"

+			/>

+			<Tool

+				Name="VCWebServiceProxyGeneratorTool"

+			/>

+			<Tool

+				Name="VCMIDLTool"

+			/>

+			<Tool

+				Name="VCCLCompilerTool"

+			/>

+			<Tool

+				Name="VCManagedResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCPreLinkEventTool"

+			/>

+			<Tool

+				Name="VCLinkerTool"

+				BaseAddress="0x1e1F0000"

+			/>

+			<Tool

+				Name="VCALinkTool"

+			/>

+			<Tool

+				Name="VCManifestTool"

+			/>

+			<Tool

+				Name="VCXDCMakeTool"

+			/>

+			<Tool

+				Name="VCBscMakeTool"

+			/>

+			<Tool

+				Name="VCFxCopTool"

+			/>

+			<Tool

+				Name="VCAppVerifierTool"

+			/>

+			<Tool

+				Name="VCPostBuildEventTool"

+			/>

+		</Configuration>

+		<Configuration

+			Name="PGInstrument|x64"

+			ConfigurationType="2"

+			InheritedPropertySheets=".\pyd.vsprops;.\x64.vsprops;.\pginstrument.vsprops"

+			CharacterSet="0"

+			WholeProgramOptimization="1"

+			>

+			<Tool

+				Name="VCPreBuildEventTool"

+			/>

+			<Tool

+				Name="VCCustomBuildTool"

+			/>

+			<Tool

+				Name="VCXMLDataGeneratorTool"

+			/>

+			<Tool

+				Name="VCWebServiceProxyGeneratorTool"

+			/>

+			<Tool

+				Name="VCMIDLTool"

+				TargetEnvironment="3"

+			/>

+			<Tool

+				Name="VCCLCompilerTool"

+			/>

+			<Tool

+				Name="VCManagedResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCPreLinkEventTool"

+			/>

+			<Tool

+				Name="VCLinkerTool"

+				BaseAddress="0x1e1F0000"

+				TargetMachine="17"

+			/>

+			<Tool

+				Name="VCALinkTool"

+			/>

+			<Tool

+				Name="VCManifestTool"

+			/>

+			<Tool

+				Name="VCXDCMakeTool"

+			/>

+			<Tool

+				Name="VCBscMakeTool"

+			/>

+			<Tool

+				Name="VCFxCopTool"

+			/>

+			<Tool

+				Name="VCAppVerifierTool"

+			/>

+			<Tool

+				Name="VCPostBuildEventTool"

+			/>

+		</Configuration>

+		<Configuration

+			Name="PGUpdate|Win32"

+			ConfigurationType="2"

+			InheritedPropertySheets=".\pyd.vsprops;.\pgupdate.vsprops"

+			CharacterSet="0"

+			WholeProgramOptimization="1"

+			>

+			<Tool

+				Name="VCPreBuildEventTool"

+			/>

+			<Tool

+				Name="VCCustomBuildTool"

+			/>

+			<Tool

+				Name="VCXMLDataGeneratorTool"

+			/>

+			<Tool

+				Name="VCWebServiceProxyGeneratorTool"

+			/>

+			<Tool

+				Name="VCMIDLTool"

+			/>

+			<Tool

+				Name="VCCLCompilerTool"

+			/>

+			<Tool

+				Name="VCManagedResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCPreLinkEventTool"

+			/>

+			<Tool

+				Name="VCLinkerTool"

+				BaseAddress="0x1e1F0000"

+			/>

+			<Tool

+				Name="VCALinkTool"

+			/>

+			<Tool

+				Name="VCManifestTool"

+			/>

+			<Tool

+				Name="VCXDCMakeTool"

+			/>

+			<Tool

+				Name="VCBscMakeTool"

+			/>

+			<Tool

+				Name="VCFxCopTool"

+			/>

+			<Tool

+				Name="VCAppVerifierTool"

+			/>

+			<Tool

+				Name="VCPostBuildEventTool"

+			/>

+		</Configuration>

+		<Configuration

+			Name="PGUpdate|x64"

+			ConfigurationType="2"

+			InheritedPropertySheets=".\pyd.vsprops;.\x64.vsprops;.\pgupdate.vsprops"

+			CharacterSet="0"

+			WholeProgramOptimization="1"

+			>

+			<Tool

+				Name="VCPreBuildEventTool"

+			/>

+			<Tool

+				Name="VCCustomBuildTool"

+			/>

+			<Tool

+				Name="VCXMLDataGeneratorTool"

+			/>

+			<Tool

+				Name="VCWebServiceProxyGeneratorTool"

+			/>

+			<Tool

+				Name="VCMIDLTool"

+				TargetEnvironment="3"

+			/>

+			<Tool

+				Name="VCCLCompilerTool"

+			/>

+			<Tool

+				Name="VCManagedResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCResourceCompilerTool"

+			/>

+			<Tool

+				Name="VCPreLinkEventTool"

+			/>

+			<Tool

+				Name="VCLinkerTool"

+				BaseAddress="0x1e1F0000"

+				TargetMachine="17"

+			/>

+			<Tool

+				Name="VCALinkTool"

+			/>

+			<Tool

+				Name="VCManifestTool"

+			/>

+			<Tool

+				Name="VCXDCMakeTool"

+			/>

+			<Tool

+				Name="VCBscMakeTool"

+			/>

+			<Tool

+				Name="VCFxCopTool"

+			/>

+			<Tool

+				Name="VCAppVerifierTool"

+			/>

+			<Tool

+				Name="VCPostBuildEventTool"

+			/>

+		</Configuration>

+	</Configurations>

+	<References>

+	</References>

+	<Files>

+		<Filter

+			Name="Source Files"

+			>

+			<File

+				RelativePath="..\Modules\_testbuffer.c"

+				>

+			</File>

+		</Filter>

+	</Files>

+	<Globals>

+	</Globals>

+</VisualStudioProject>

diff --git a/PCbuild/pcbuild.sln b/PCbuild/pcbuild.sln
index 9efb6d9496..992e66a166 100644
--- a/PCbuild/pcbuild.sln
+++ b/PCbuild/pcbuild.sln
@@ -142,6 +142,11 @@ Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "python3dll", "python3dll.vc
 EndProject

 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "xxlimited", "xxlimited.vcproj", "{F749B822-B489-4CA5-A3AD-CE078F5F338A}"

 EndProject

+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "_testbuffer", "_testbuffer.vcproj", "{A2697BD3-28C1-4AEC-9106-8B748639FD16}"

+	ProjectSection(ProjectDependencies) = postProject

+		{CF7AC3D1-E2DF-41D2-BEA6-1E2556CDEA26} = {CF7AC3D1-E2DF-41D2-BEA6-1E2556CDEA26}

+	EndProjectSection

+EndProject

 Global

 	GlobalSection(SolutionConfigurationPlatforms) = preSolution

 		Debug|Win32 = Debug|Win32

@@ -609,6 +614,22 @@ Global
 		{F749B822-B489-4CA5-A3AD-CE078F5F338A}.Release|Win32.Build.0 = Release|Win32

 		{F749B822-B489-4CA5-A3AD-CE078F5F338A}.Release|x64.ActiveCfg = Release|x64

 		{F749B822-B489-4CA5-A3AD-CE078F5F338A}.Release|x64.Build.0 = Release|x64

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.Debug|Win32.ActiveCfg = Debug|Win32

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.Debug|Win32.Build.0 = Debug|Win32

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.Debug|x64.ActiveCfg = Debug|x64

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.Debug|x64.Build.0 = Debug|x64

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.PGInstrument|Win32.ActiveCfg = PGInstrument|Win32

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.PGInstrument|Win32.Build.0 = PGInstrument|Win32

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.PGInstrument|x64.ActiveCfg = PGInstrument|x64

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.PGInstrument|x64.Build.0 = PGInstrument|x64

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.PGUpdate|Win32.ActiveCfg = PGUpdate|Win32

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.PGUpdate|Win32.Build.0 = PGUpdate|Win32

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.PGUpdate|x64.ActiveCfg = PGUpdate|x64

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.PGUpdate|x64.Build.0 = PGUpdate|x64

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.Release|Win32.ActiveCfg = Release|Win32

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.Release|Win32.Build.0 = Release|Win32

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.Release|x64.ActiveCfg = Release|x64

+		{A2697BD3-28C1-4AEC-9106-8B748639FD16}.Release|x64.Build.0 = Release|x64

 	EndGlobalSection

 	GlobalSection(SolutionProperties) = preSolution

 		HideSolutionNode = FALSE

diff --git a/PCbuild/readme.txt b/PCbuild/readme.txt
index f47d555248..2146221b1d 100644
--- a/PCbuild/readme.txt
+++ b/PCbuild/readme.txt
@@ -92,6 +92,9 @@ _socket
 _testcapi
     tests of the Python C API, run via Lib/test/test_capi.py, and
     implemented by module Modules/_testcapimodule.c
+_testbuffer
+    buffer protocol tests, run via Lib/test/test_buffer.py, and
+    implemented by module Modules/_testbuffer.c
 pyexpat
     Python wrapper for accelerated XML parsing, which incorporates stable
     code from the Expat project:  http://sourceforge.net/projects/expat/
diff --git a/setup.py b/setup.py
index 39aff67ab3..cad293b1fa 100644
--- a/setup.py
+++ b/setup.py
@@ -530,6 +530,8 @@ class PyBuildExt(build_ext):
         # Python C API test module
         exts.append( Extension('_testcapi', ['_testcapimodule.c'],
                                depends=['testcapi_long.h']) )
+        # Python PEP-3118 (buffer protocol) test module
+        exts.append( Extension('_testbuffer', ['_testbuffer.c']) )
         # profiler (_lsprof is for cProfile.py)
         exts.append( Extension('_lsprof', ['_lsprof.c', 'rotatingtree.c']) )
         # static Unicode character database