int compress (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen);

int compress2 (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen, int level);

int uncompress (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen);

typedef voidp gzFile;

gzFile gzopen (const char *path, const char *mode);

gzFile gzdopen (int fd, const char *mode);

int gzsetparams (gzFile file, int level, int strategy);

int gzread (gzFile file, voidp buf, unsigned len);

int gzwrite (gzFile file, const voidp buf, unsigned len);

int VA gzprintf (gzFile file, const char *format, ...);

int gzputs (gzFile file, const char *s);

char * gzgets (gzFile file, char *buf, int len);

int gzputc (gzFile file, int c);

int gzgetc (gzFile file);

int gzflush (gzFile file, int flush);

z_off_t gzseek (gzFile file, z_off_t offset, int whence);

z_off_t gztell (gzFile file);

int gzrewind (gzFile file);

int gzeof (gzFile file);

int gzclose (gzFile file);

const char * gzerror (gzFile file, int *errnum);

 const char * zlibVersion (void);

 int deflateInit (z_streamp strm, int level);

 int deflate (z_streamp strm, int flush);

 int deflateEnd (z_streamp strm);

 int inflateInit (z_streamp strm);

 int inflate (z_streamp strm, int flush);

 int inflateEnd (z_streamp strm);

  int deflateInit2 (z_streamp strm,

  int deflateSetDictionary (z_streamp strm, const Bytef *dictionary, uInt dictLength);

  int deflateCopy (z_streamp dest, z_streamp source);

  int deflateReset (z_streamp strm);

  int deflateParams (z_streamp strm, int level, int strategy);

  int inflateInit2 (z_streamp strm, int windowBits);

  int inflateSetDictionary (z_streamp strm, const Bytef *dictionary, uInt dictLength);

  int inflateSync (z_streamp strm);

  int inflateReset (z_streamp strm);

   uLong adler32 (uLong adler, const Bytef *buf, uInt len);

   uLong crc32 (uLong crc, const Bytef *buf, uInt len);

   struct z_stream_s

   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;

#define Z_NO_FLUSH      0

#define Z_PARTIAL_FLUSH 1      /* †要被删除, 使用Z_SYNC_FLUSH 代替他们 */

#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)    /* 压缩/解压缩的返回值.负值是错误,正值是特殊但是正常的值. */

#define Z_NO_COMPRESSION         0

#define Z_BEST_SPEED             1

#define Z_BEST_COMPRESSION       9

#define Z_DEFAULT_COMPRESSION (-1)     /* 压缩级别 */

#define Z_FILTERED            1

#define Z_HUFFMAN_ONLY        2

#define Z_DEFAULT_STRATEGY    0         /* 压缩策略; 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                     /* 用于初始化zalloc, zfree, opaque */

#define zlib_version zlibVersion()      /* 用于和1.0.2以前的版本兼容*/

const char * zError (int err);

int inflateSyncPoint (z_streamp z);

const uLongf * get_crc_table (void);

    const char * zlibVersion (void); 
    int deflateInit (z_streamp strm, int level); 
    int deflate (z_streamp strm, int flush); 
    int deflateEnd (z_streamp strm); 
    int inflateInit (z_streamp strm); 
    int inflate (z_streamp strm, int flush); 
    int inflateEnd (z_streamp strm); 
    函数说明：

    const char * zlibVersion (void); 
    应用程序会比较zlibVersion和ZLIB_VERSION的一致性。
    如果第一个字不同，说明zlib和应用程序使用的zlib.h是不一致的。这个检查将被defalteInit和infalteInit自动调用。

    int deflateInit (z_streamp strm, int level); 
    为压缩初始化内部流的状态。
    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().


    int deflate (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).


    int deflateEnd (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).


    int inflateInit (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 value depends on the compression method), inflateInit determines the compression method from the zlib header and allocates all data structures accordingly ; otherwise the allocation will be deferred to the first call of inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to use default allocation functions. 
inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough memory, Z_VERSION_ERROR if the zlib library version is incompatible with the version assumed by the caller. msg is set to null if there is no error message. inflateInit does not perform any decompression apart from reading the zlib header if present: this will be done by inflate(). (So next_in and avail_in may be modified, but next_out and avail_out are unchanged.)


    int inflate (z_streamp strm, int flush); 
    inflate decompresses as much data as possible, and stops when the input buffer becomes empty or the output buffer becomes full. It may some introduce some output latency (reading input without producing any output) except when forced to flush. 
    The detailed semantics are as follows. inflate 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() provides as much output as possible, until there is no more input data or no more space in the output buffer (see below about the flush parameter). 
    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 it wants, for example when the output buffer is full (avail_out == 0), or after each call of inflate(). If inflate 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, inflate flushes as much output as possible to the output buffer. The flushing behavior of inflate is not specified for values of the flush parameter other than Z_SYNC_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. The use of Z_FINISH is never required, but can be used to inform inflate that a faster routine may be used for the single inflate() call.

    If a preset dictionary is needed at this point (see inflateSetDictionary below), inflate sets strm-adler to the adler32 checksum of the dictionary chosen by the compressor and returns Z_NEED_DICT ; otherwise it sets strm-> adler to the adler32 checksum of all output produced so far (that is, total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described below. At the end of the stream, inflate() checks that its computed adler32 checksum is equal to that saved by the compressor and returns Z_STREAM_END only if the checksum is correct.

    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 and all uncompressed output has been produced, Z_NEED_DICT if a preset dictionary is needed at this point, Z_DATA_ERROR if the input data was corrupted (input stream not conforming to the zlib format or incorrect adler32 checksum), 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.


    int inflateEnd (z_streamp strm);