zlib.h

一个国人自己实现图像库的程序（有参考价值）

/* zlib.h -- interface of the 'zlib' general purpose compression library
  version 1.1.3, July 9th, 1998

  Copyright (C) 1995-1998 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
  [e-mail]          [e-mail]


  The data format used by the zlib library is described by RFCs (Request for
  Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt
  (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
*/

#ifndef _ZLIB_H
#define _ZLIB_H

#include "zconf.h"

#ifdef __cplusplus
extern "C" {
#endif

#define ZLIB_VERSION "1.1.3"

/* 
     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 will be added later and will have the same
  stream interface.

     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.

     The library also supports reading and writing files in gzip (.gz) format
  with an interface similar to that of stdio.

     The library does not install any signal handler. The decoder checks
  the consistency of the compressed data, so the library should never
  crash even in case of corrupted input.
*/

typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
typedef void   (*free_func)  OF((voidpf opaque, voidpf address));

struct internal_state;

typedef struct z_stream_s {
    Bytef    *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 */

    Bytef    *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 FAR *state; /* not visible by applications */

    alloc_func zalloc;  /* used to allocate the internal state */
    free_func  zfree;   /* used to free the internal state */
    voidpf     opaque;  /* private data object passed to zalloc and zfree */

    int     data_type;  /* best guess about the data type: ascii or binary */
    uLong   adler;      /* adler32 value of the uncompressed data */
    uLong   reserved;   /* reserved for future use */
} z_stream;

typedef z_stream FAR *z_streamp;

/*
   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 the 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.
   If zlib is used in a multi-threaded application, zalloc and zfree must be
   thread safe.

   On 16-bit systems, the functions zalloc and zfree must be able to allocate
   exactly 65536 bytes, but will not be required to allocate more than this
   if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
   pointers returned by zalloc for objects of exactly 65536 bytes *must*
   have their offset normalized to zero. The default allocation function
   provided by this library ensures this (see zutil.c). To reduce memory
   requirements and avoid any allocation of 64K objects, at the expense of
   compression ratio, compile the library with -DMAX_WBITS=14 (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 /* will be removed, use Z_SYNC_FLUSH instead */
#define Z_SYNC_FLUSH    2
#define Z_FULL_FLUSH    3
#define Z_FINISH        4
/* Allowed flush values; see deflate() below for details */

#define Z_OK            0
#define Z_STREAM_END    1
#define Z_NEED_DICT     2
#define Z_ERRNO        (-1)
#define Z_STREAM_ERROR (-2)
#define Z_DATA_ERROR   (-3)
#define Z_MEM_ERROR    (-4)
#define Z_BUF_ERROR    (-5)
#define Z_VERSION_ERROR (-6)
/* Return codes for the compression/decompression functions. Negative
 * values are errors, positive values are used for special but normal events.
 */

#define Z_NO_COMPRESSION         0
#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
/* compression strategy; see deflateInit2() below for details */

#define Z_BINARY   0
#define Z_ASCII    1
#define Z_UNKNOWN  2
/* Possible values of the data_type field */

#define Z_DEFLATED   8
/* The deflate compression method (the only one supported in this version) */

#define Z_NULL  0  /* for initializing zalloc, zfree, opaque */

#define zlib_version zlibVersion()
/* for compatibility with versions < 1.0.2 */

                        /* basic functions */

ZEXTERN const char * ZEXPORT zlibVersion OF((void));
/* The application can compare zlibVersion 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.
   This check is automatically made by deflateInit and inflateInit.
 */

/* 
ZEXTERN int ZEXPORT deflateInit OF((z_streamp 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 0 and 9:
   1 gives best speed, 9 gives best compression, 0 gives no compression at
   all (the input data is simply copied a block at a time).
   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 level is not a valid compression level,
   Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
   with the version assumed by the caller (ZLIB_VERSION).
   msg is set to null if there is no error message.  deflateInit does not
   perform any compression: this will be done by deflate().
*/


ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
/*
    deflate compresses as much data as possible, and stops when the input
  buffer becomes empty or the output buffer becomes full. It may introduce some
  output latency (reading input without producing any output) except when
  forced to flush.

    The detailed semantics are as follows. deflate 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 and avail_in are 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; avail_out
  should never be zero before the call. The application can consume the
  compressed output when it wants, for example when the output buffer is full
  (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
  and with zero avail_out, it must be called again after making room in the
  output buffer because there might be more output pending.

    If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
  flushed to the output buffer and the output is aligned on a byte boundary, so
  that the decompressor can get all input data available so far. (In particular
  avail_in is zero after the call if enough output space has been provided
  before the call.)  Flushing may degrade compression for some compression
  algorithms and so it should be used only when necessary.

    If flush is set to Z_FULL_FLUSH, all output is flushed as with
  Z_SYNC_FLUSH, and the compression state is reset so that decompression can
  restart from this point if previous compressed data has been damaged or if
  random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
  the compression.

    If deflate returns with avail_out == 0, this function must be called again
  with the same value of the flush parameter and more output space (updated
  avail_out), until the flush is complete (deflate returns with non-zero
  avail_out).

    If the parameter flush is set to Z_FINISH, pending input is processed,
  pending output is flushed and deflate returns with Z_STREAM_END if there
  was enough output space; if deflate returns with Z_OK, this function must be
  called again with Z_FINISH and more output space (updated avail_out) but no
  more input data, until it returns with Z_STREAM_END or an error. After
  deflate has returned Z_STREAM_END, the only possible operations on the
  stream are deflateReset or deflateEnd.
  
    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 12 bytes.  If deflate does not return
  Z_STREAM_END, then it must be called again as described above.

    deflate() sets strm->adler to the adler32 checksum of all input read
  so far (that is, total_in bytes).

    deflate() may update 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() returns Z_OK if some progress has been made (more input
  processed or more output produced), Z_STREAM_END if all input has been
  consumed and all output has been produced (only when flush is set to
  Z_FINISH), 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
  (for example avail_in or avail_out was zero).
*/


ZEXTERN int ZEXPORT deflateEnd OF((z_streamp 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, Z_DATA_ERROR if the stream was freed
   prematurely (some input or output was discarded). In the error case,
   msg may be set but then points to a static string (which must not be
   deallocated).
*/


/* 
ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));

     Initializes the internal stream state for decompression. The fields
   next_in, avail_in, zalloc, zfree and opaque must be initialized before by
   the caller. If next_in is not Z_NULL and avail_in is large enough (the exact