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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- S Y S T E M . M E M O R Y --
-- --
-- S p e c --
-- --
-- Copyright (C) 2001-2003 Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 2, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
-- Boston, MA 02110-1301, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- This package provides the low level memory allocation/deallocation
-- mechanisms used by GNAT.
-- To provide an alternate implementation, simply recompile the modified
-- body of this package with gnatmake -u -a -g s-memory.adb and make sure
-- that the ali and object files for this unit are found in the object
-- search path.
-- This unit may be used directly from an application program by providing
-- an appropriate WITH, and the interface can be expected to remain stable.
package System.Memory is
pragma Elaborate_Body;
type size_t is mod 2 ** Standard'Address_Size;
-- Note: the reason we redefine this here instead of using the
-- definition in Interfaces.C is that we do not want to drag in
-- all of Interfaces.C just because System.Memory is used.
function Alloc (Size : size_t) return System.Address;
-- This is the low level allocation routine. Given a size in storage
-- units, it returns the address of a maximally aligned block of
-- memory. The implementation of this routine is guaranteed to be
-- task safe, and also aborts are deferred if necessary.
--
-- If size_t is set to size_t'Last on entry, then a Storage_Error
-- exception is raised with a message "object too large".
--
-- If size_t is set to zero on entry, then a minimal (but non-zero)
-- size block is allocated.
--
-- Note: this is roughly equivalent to the standard C malloc call
-- with the additional semantics as described above.
procedure Free (Ptr : System.Address);
-- This is the low level free routine. It frees a block previously
-- allocated with a call to Alloc. As in the case of Alloc, this
-- call is guaranteed task safe, and aborts are deferred.
--
-- Note: this is roughly equivalent to the standard C free call
-- with the additional semantics as described above.
function Realloc
(Ptr : System.Address;
Size : size_t)
return System.Address;
-- This is the low level reallocation routine. It takes an existing
-- block address returned by a previous call to Alloc or Realloc,
-- and reallocates the block. The size can either be increased or
-- decreased. If possible the reallocation is done in place, so that
-- the returned result is the same as the value of Ptr on entry.
-- However, it may be necessary to relocate the block to another
-- address, in which case the information is copied to the new
-- block, and the old block is freed. The implementation of this
-- routine is guaranteed to be task safe, and also aborts are
-- deferred as necessary.
--
-- If size_t is set to size_t'Last on entry, then a Storage_Error
-- exception is raised with a message "object too large".
--
-- If size_t is set to zero on entry, then a minimal (but non-zero)
-- size block is allocated.
--
-- Note: this is roughly equivalent to the standard C realloc call
-- with the additional semantics as described above.
private
-- The following names are used from the generated compiler code
pragma Export (C, Alloc, "__gnat_malloc");
pragma Export (C, Free, "__gnat_free");
pragma Export (C, Realloc, "__gnat_realloc");
end System.Memory;
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