/* zlib.h -- interface of the 'zlib' general purpose compression library version 0.7 April 14th, 1995. Copyright (C) 1995 Jean-loup Gailly and Mark Adler This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. 3. This notice may not be removed or altered from any source distribution. Jean-loup Gailly Mark Adler gzip@prep.ai.mit.edu madler@cco.caltech.edu */ #ifndef _ZLIB_H #define _ZLIB_H #include "zconf.h" #define ZLIB_VERSION "0.7" /* The 'zlib' compression library provides in-memory compression and decompression functions, including integrity checks of the uncompressed data. This version of the library supports only one compression method (deflation) but other algorithms may be added later and will have the same stream interface. For compression the application must provide the output buffer and may optionally provide the input buffer for optimization. For decompression, the application must provide the input buffer and may optionally provide the output buffer for optimization. Compression can be done in a single step if the buffers are large enough (for example if an input file is mmap'ed), or can be done by repeated calls of the compression function. In the latter case, the application must provide more input and/or consume the output (providing more output space) before each call. */ typedef voidp (*alloc_func) __P((voidp opaque, uInt items, uInt size)); typedef void (*free_func) __P((voidp opaque, voidp address)); struct internal_state; typedef struct z_stream_s { Byte *next_in; /* next input byte */ uInt avail_in; /* number of bytes available at next_in */ uLong total_in; /* total nb of input bytes read so far */ Byte *next_out; /* next output byte should be put there */ uInt avail_out; /* remaining free space at next_out */ uLong total_out; /* total nb of bytes output so far */ char *msg; /* last error message, NULL if no error */ struct internal_state *state; /* not visible by applications */ alloc_func zalloc; /* used to allocate the internal state */ free_func zfree; /* used to free the internal state */ voidp opaque; /* private data object passed to zalloc and zfree */ Byte data_type; /* best guess about the data type: ascii or binary */ } z_stream; /* The application must update next_in and avail_in when avail_in has dropped to zero. It must update next_out and avail_out when avail_out has dropped to zero. The application must initialize zalloc, zfree and opaque before calling the init function. All other fields are set by the compression library and must not be updated by the application. The opaque value provided by the application will be passed as first parameter for calls of zalloc and zfree. This can be useful for custom memory management. The compression library attaches no meaning to the opaque value. zalloc must return Z_NULL if there is not enough memory for the object. On 16-bit systems, the functions zalloc and zfree must be able to allocate exactly 65536 bytes, but will not be require to allocate more than this if the symbol MAXSEG_64K is defined (see zconf.h). The fields total_in and total_out can be used for statistics or progress reports. After compression, total_in holds the total size of the uncompressed data and may be saved for use in the decompressor (particularly if the decompressor wants to decompress everything in a single step). */ /* constants */ #define Z_NO_FLUSH 0 #define Z_PARTIAL_FLUSH 1 #define Z_FULL_FLUSH 2 #define Z_FINISH 4 /* See deflate() below for the usage of these constants */ #define Z_OK 0 #define Z_STREAM_END 1 #define Z_ERRNO (-1) #define Z_STREAM_ERROR (-2) #define Z_DATA_ERROR (-3) #define Z_MEM_ERROR (-4) #define Z_BUF_ERROR (-5) /* error codes for the compression/decompression functions */ #define Z_BEST_SPEED 1 #define Z_BEST_COMPRESSION 9 #define Z_DEFAULT_COMPRESSION (-1) /* compression levels */ #define Z_FILTERED 1 #define Z_HUFFMAN_ONLY 2 #define Z_DEFAULT_STRATEGY 0 #define Z_BINARY 0 #define Z_ASCII 1 #define Z_UNKNOWN 2 /* Used to set the data_type field */ #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */ extern char *zlib_version; /* The application can compare zlib_version and ZLIB_VERSION for consistency. If the first character differs, the library code actually used is not compatible with the zlib.h header file used by the application. */ /* basic functions */ extern int deflateInit __P((z_stream *strm, int level)); /* Initializes the internal stream state for compression. The fields zalloc, zfree and opaque must be initialized before by the caller. If zalloc and zfree are set to Z_NULL, deflateInit updates them to use default allocation functions. The compression level must be Z_DEFAULT_COMPRESSION, or between 1 and 9: 1 gives best speed, 9 gives best compression. Z_DEFAULT_COMPRESSION requests a default compromise between speed and compression (currently equivalent to level 6). deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough memory, Z_STREAM_ERROR if the stream state was inconsistent (such as zalloc being NULL). msg is set to null if there is no error message. deflateInit does not perform any compression: this will be done by deflate(). */ extern int deflate __P((z_stream *strm, int flush)); /* Performs one or both of the following actions: - Compress more input starting at next_in and update next_in and avail_in accordingly. If not all input can be processed (because there is not enough room in the output buffer), next_in is updated and processing will resume at this point for the next call of deflate(). - Provide more output starting at next_out and update next_out and avail_out accordingly. This action is forced if the parameter flush is non zero. Forcing flush frequently degrades the compression ratio, so this parameter should be set only when necessary (in interactive applications). Some output may be provided even if flush is not set. Before the call of deflate(), the application should ensure that at least one of the actions is possible, by providing more input and/or consuming more output, and updating avail_in or avail_out accordingly. The application can consume the compressed output when the output buffer is full (avail_out == 0), or after each call of deflate(). If the parameter flush is set to Z_PARTIAL_FLUSH, the current compression block is byte aligned and flushed to the output buffer so that the decompressor can get all input data available so far; if the compression method is 8 (deflate without partial flush capability), the current block is terminated. If flush is set to Z_FULL_FLUSH, the compression block is terminated, a special marker is output and the compression dictionary is discarded; this is useful to allow the decompressor to synchronize if one compressed block has been damaged. Flushing degrades compression and so should be used only when necessary. Using Z_FULL_FLUSH too often can seriously degrade the compression. If the parameter flush is set to Z_FINISH, all pending input is processed and all pending output is flushed. The next operation on this stream must be another call of deflate with Z_FINISH but no more input data (unchanged avail_in) if this call returned with avail_out equal to zero, or a call of deflateEnd to deallocate the compression state. Z_FINISH can be used immediately after deflateInit if all the compression is to be done in a single step. In this case, avail_out must be at least 0.1% larger than avail_in plus 8 bytes. deflate() may update strm->data_type if it can make a good guess about the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered binary. This field is only for information purposes and does not affect the compression algorithm in any manner. deflate() return Z_OK if some progress has been made (more input processed or more output produced), Z_STREAM_ERROR if the stream state was inconsistent (for example if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible or if there was not enough room in the output buffer when Z_FINISH is used. */ extern int deflateEnd __P((z_stream *strm)); /* All dynamically allocated data structures for this stream are freed. This function discards any unprocessed input and does not flush any pending output. deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state was inconsistent. In the error case, msg may be set but then points to a static string (which must not be deallocated). */ extern int inflateInit __P((z_stream *strm)); /* Initializes the internal stream state for decompression. The fields zalloc and zfree must be initialized before by the caller. If zalloc and zfree are set to Z_NULL, deflateInit updates them to use default allocation functions. inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough memory, Z_STREAM_ERROR if the stream state was inconsistent (such as zalloc being NULL). msg is set to null if there is no error message. inflateInit does not perform any decompression: this will be done by inflate(). */ extern int inflate __P((z_stream *strm, int flush)); /* Performs one or both of the following actions: - Decompress more input starting at next_in and update next_in and avail_in accordingly. If not all input can be processed (because there is not enough room in the output buffer), next_in is updated and processing will resume at this point for the next call of inflate(). - Provide more output starting at next_out and update next_out and avail_out accordingly. inflate() always provides as much output as possible (until no more input data or no more space in the output buffer). Before the call of inflate(), the application should ensure that at least one of the actions is possible, by providing more input and/or consuming more output, and updating the next_* and avail_* values accordingly. The application can consume the uncompressed output when the output buffer is full (avail_out == 0), or after each call of inflate(). If the parameter flush is set to Z_PARTIAL_FLUSH, inflate flushes as much output as possible to the output buffer. The flushing behavior of inflate is not specified for values of the flush paramater other than Z_PARTIAL_FLUSH and Z_FINISH, but the current implementation actually flushes as much output as possible anyway. inflate() should normally be called until it returns Z_STREAM_END or an error. However if all decompression is to be performed in a single step (a single call of inflate), the parameter flush should be set to Z_FINISH. In this case all pending input is processed and all pending output is flushed; avail_out must be large enough to hold all the uncompressed data. (The size of the uncompressed data may have been saved by the compressor for this purpose.) The next operation on this stream must be inflateEnd to deallocate the decompression state. inflate() returns Z_OK if some progress has been made (more input processed or more output produced), Z_STREAM_END if the end of the compressed data has been reached, Z_DATA_ERROR if the input data was corrupted, Z_STREAM_ERROR if the stream structure was inconsistent (for example if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR if no progress is possible or if there was not enough room in the output buffer when Z_FINISH is used. In the Z_DATA_ERROR case, the application may then call inflateSync to look for a good compression block. */ extern int inflateEnd __P((z_stream *strm)); /* All dynamically allocated data structures for this stream are freed. This function discards any unprocessed input and does not flush any pending output. inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state was inconsistent. In the error case, msg may be set but then points to a static string (which must not be deallocated). */ /* advanced functions */ /* The following functions are needed only in some special applications. */ extern int deflateInit2 __P((z_stream *strm, int level, int method, int windowBits, int memLevel, int strategy)); /* This is another version of deflateInit with more compression options. The fields next_in, zalloc and zfree must be initialized before by the caller. The method parameter is the compression method. It must be 8 in this version of the library. (Method 9 will allow a 64K history buffer and partial block flushes.) The windowBits parameter is the base two logarithm of the window size (the size of the history buffer). It should be in the range 8..15 for this version of the library (the value 16 will be allowed soon). Larger values of this parameter result in better compression at the expense of memory usage. The default value is 15 if deflateInit is used instead. The memLevel parameter specifies how much memory should be allocated for the internal compression state. memLevel=1 uses minimum memory but is slow and reduces compression ratio; memLevel=9 uses maximum memory for optimal speed. The default value is 8. The strategy parameter is used to tune the compression algorithm. Use the value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no string match). Filtered data consists mostly of small values with a somewhat random distribution. In this case, the compression algorithm is tuned to compress them better. The strategy parameter only affects the compression ratio but not the correctness of the compressed output even if it is not set appropriately. If next_in is not null, the library will use this buffer to hold also some history information; the buffer must either hold the entire input data, or have at least (1<