zlib.h

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00001 // $Id: zlib.h 751 2006-03-31 15:43:49Z alex $
00002 
00003 /* @@tag:xara-cn-tp@@ THIRD PARTY COPYRIGHT */
00004 /* zlib.h -- interface of the 'zlib' general purpose compression library
00005   version 1.2.2, October 3rd, 2004
00006 
00007   MODIFIED FOR USE IN XARA LX - THIS IS NOT THE ORIGINAL UNMODIFIED SOURCE CODE
00008 
00009   Copyright (C) 1995-2004 Jean-loup Gailly and Mark Adler
00010 
00011   This software is provided 'as-is', without any express or implied
00012   warranty.  In no event will the authors be held liable for any damages
00013   arising from the use of this software.
00014 
00015   Permission is granted to anyone to use this software for any purpose,
00016   including commercial applications, and to alter it and redistribute it
00017   freely, subject to the following restrictions:
00018 
00019   1. The origin of this software must not be misrepresented; you must not
00020      claim that you wrote the original software. If you use this software
00021      in a product, an acknowledgment in the product documentation would be
00022      appreciated but is not required.
00023   2. Altered source versions must be plainly marked as such, and must not be
00024      misrepresented as being the original software.
00025   3. This notice may not be removed or altered from any source distribution.
00026 
00027   Jean-loup Gailly        Mark Adler
00028   jloup@gzip.org          madler@alumni.caltech.edu
00029 
00030 
00031   The data format used by the zlib library is described by RFCs (Request for
00032   Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt
00033   (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
00034 */
00035 
00036 #ifndef ZLIB_H
00037 #define ZLIB_H
00038 
00039 #include "zconf.h"
00040 
00041 #ifdef __cplusplus
00042 extern "C" {
00043 #endif
00044 
00045 #define ZLIB_VERSION "1.2.2"
00046 #define ZLIB_VERNUM 0x1220
00047 
00048 /*
00049      The 'zlib' compression library provides in-memory compression and
00050   decompression functions, including integrity checks of the uncompressed
00051   data.  This version of the library supports only one compression method
00052   (deflation) but other algorithms will be added later and will have the same
00053   stream interface.
00054 
00055      Compression can be done in a single step if the buffers are large
00056   enough (for example if an input file is mmap'ed), or can be done by
00057   repeated calls of the compression function.  In the latter case, the
00058   application must provide more input and/or consume the output
00059   (providing more output space) before each call.
00060 
00061      The compressed data format used by default by the in-memory functions is
00062   the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
00063   around a deflate stream, which is itself documented in RFC 1951.
00064 
00065      The library also supports reading and writing files in gzip (.gz) format
00066   with an interface similar to that of stdio using the functions that start
00067   with "gz".  The gzip format is different from the zlib format.  gzip is a
00068   gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
00069 
00070      This library can optionally read and write gzip streams in memory as well.
00071 
00072      The zlib format was designed to be compact and fast for use in memory
00073   and on communications channels.  The gzip format was designed for single-
00074   file compression on file systems, has a larger header than zlib to maintain
00075   directory information, and uses a different, slower check method than zlib.
00076 
00077      The library does not install any signal handler. The decoder checks
00078   the consistency of the compressed data, so the library should never
00079   crash even in case of corrupted input.
00080 */
00081 
00082 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
00083 typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
00084 
00085 struct internal_state;
00086 
00087 typedef struct z_stream_s {
00088     Bytef    *next_in;  /* next input byte */
00089     uInt     avail_in;  /* number of bytes available at next_in */
00090     uLong    total_in;  /* total nb of input bytes read so far */
00091 
00092     Bytef    *next_out; /* next output byte should be put there */
00093     uInt     avail_out; /* remaining free space at next_out */
00094     uLong    total_out; /* total nb of bytes output so far */
00095 
00096     char     *msg;      /* last error message, NULL if no error */
00097     struct internal_state FAR *state; /* not visible by applications */
00098 
00099     alloc_func zalloc;  /* used to allocate the internal state */
00100     free_func  zfree;   /* used to free the internal state */
00101     voidpf     opaque;  /* private data object passed to zalloc and zfree */
00102 
00103     INT32     data_type;  /* best guess about the data type: ascii or binary */
00104     uLong   adler;      /* adler32 value of the uncompressed data */
00105     uLong   reserved;   /* reserved for future use */
00106 } z_stream;
00107 
00108 typedef z_stream FAR *z_streamp;
00109 
00110 /*
00111    The application must update next_in and avail_in when avail_in has
00112    dropped to zero. It must update next_out and avail_out when avail_out
00113    has dropped to zero. The application must initialize zalloc, zfree and
00114    opaque before calling the init function. All other fields are set by the
00115    compression library and must not be updated by the application.
00116 
00117    The opaque value provided by the application will be passed as the first
00118    parameter for calls of zalloc and zfree. This can be useful for custom
00119    memory management. The compression library attaches no meaning to the
00120    opaque value.
00121 
00122    zalloc must return Z_NULL if there is not enough memory for the object.
00123    If zlib is used in a multi-threaded application, zalloc and zfree must be
00124    thread safe.
00125 
00126    On 16-bit systems, the functions zalloc and zfree must be able to allocate
00127    exactly 65536 bytes, but will not be required to allocate more than this
00128    if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
00129    pointers returned by zalloc for objects of exactly 65536 bytes *must*
00130    have their offset normalized to zero. The default allocation function
00131    provided by this library ensures this (see zutil.c). To reduce memory
00132    requirements and avoid any allocation of 64K objects, at the expense of
00133    compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
00134 
00135    The fields total_in and total_out can be used for statistics or
00136    progress reports. After compression, total_in holds the total size of
00137    the uncompressed data and may be saved for use in the decompressor
00138    (particularly if the decompressor wants to decompress everything in
00139    a single step).
00140 */
00141 
00142                         /* constants */
00143 
00144 #define Z_NO_FLUSH      0
00145 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
00146 #define Z_SYNC_FLUSH    2
00147 #define Z_FULL_FLUSH    3
00148 #define Z_FINISH        4
00149 #define Z_BLOCK         5
00150 /* Allowed flush values; see deflate() and inflate() below for details */
00151 
00152 #define Z_OK            0
00153 #define Z_STREAM_END    1
00154 #define Z_NEED_DICT     2
00155 #define Z_ERRNO        (-1)
00156 #define Z_STREAM_ERROR (-2)
00157 #define Z_DATA_ERROR   (-3)
00158 #define Z_MEM_ERROR    (-4)
00159 #define Z_BUF_ERROR    (-5)
00160 #define Z_VERSION_ERROR (-6)
00161 /* Return codes for the compression/decompression functions. Negative
00162  * values are errors, positive values are used for special but normal events.
00163  */
00164 
00165 #define Z_NO_COMPRESSION         0
00166 #define Z_BEST_SPEED             1
00167 #define Z_BEST_COMPRESSION       9
00168 #define Z_DEFAULT_COMPRESSION  (-1)
00169 /* compression levels */
00170 
00171 #define Z_FILTERED            1
00172 #define Z_HUFFMAN_ONLY        2
00173 #define Z_RLE                 3
00174 #define Z_DEFAULT_STRATEGY    0
00175 /* compression strategy; see deflateInit2() below for details */
00176 
00177 #define Z_BINARY   0
00178 #define Z_ASCII    1
00179 #define Z_UNKNOWN  2
00180 /* Possible values of the data_type field (though see inflate()) */
00181 
00182 #define Z_DEFLATED   8
00183 /* The deflate compression method (the only one supported in this version) */
00184 
00185 #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
00186 
00187 #define zlib_version zlibVersion()
00188 /* for compatibility with versions < 1.0.2 */
00189 
00190                         /* basic functions */
00191 
00192 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
00193 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
00194    If the first character differs, the library code actually used is
00195    not compatible with the zlib.h header file used by the application.
00196    This check is automatically made by deflateInit and inflateInit.
00197  */
00198 
00199 /*
00200 ZEXTERN INT32 ZEXPORT deflateInit OF((z_streamp strm, INT32 level));
00201 
00202      Initializes the internal stream state for compression. The fields
00203    zalloc, zfree and opaque must be initialized before by the caller.
00204    If zalloc and zfree are set to Z_NULL, deflateInit updates them to
00205    use default allocation functions.
00206 
00207      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
00208    1 gives best speed, 9 gives best compression, 0 gives no compression at
00209    all (the input data is simply copied a block at a time).
00210    Z_DEFAULT_COMPRESSION requests a default compromise between speed and
00211    compression (currently equivalent to level 6).
00212 
00213      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
00214    enough memory, Z_STREAM_ERROR if level is not a valid compression level,
00215    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
00216    with the version assumed by the caller (ZLIB_VERSION).
00217    msg is set to null if there is no error message.  deflateInit does not
00218    perform any compression: this will be done by deflate().
00219 */
00220 
00221 
00222 ZEXTERN INT32 ZEXPORT deflate OF((z_streamp strm, INT32 flush));
00223 /*
00224     deflate compresses as much data as possible, and stops when the input
00225   buffer becomes empty or the output buffer becomes full. It may introduce some
00226   output latency (reading input without producing any output) except when
00227   forced to flush.
00228 
00229     The detailed semantics are as follows. deflate performs one or both of the
00230   following actions:
00231 
00232   - Compress more input starting at next_in and update next_in and avail_in
00233     accordingly. If not all input can be processed (because there is not
00234     enough room in the output buffer), next_in and avail_in are updated and
00235     processing will resume at this point for the next call of deflate().
00236 
00237   - Provide more output starting at next_out and update next_out and avail_out
00238     accordingly. This action is forced if the parameter flush is non zero.
00239     Forcing flush frequently degrades the compression ratio, so this parameter
00240     should be set only when necessary (in interactive applications).
00241     Some output may be provided even if flush is not set.
00242 
00243   Before the call of deflate(), the application should ensure that at least
00244   one of the actions is possible, by providing more input and/or consuming
00245   more output, and updating avail_in or avail_out accordingly; avail_out
00246   should never be zero before the call. The application can consume the
00247   compressed output when it wants, for example when the output buffer is full
00248   (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
00249   and with zero avail_out, it must be called again after making room in the
00250   output buffer because there might be more output pending.
00251 
00252     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
00253   flushed to the output buffer and the output is aligned on a byte boundary, so
00254   that the decompressor can get all input data available so far. (In particular
00255   avail_in is zero after the call if enough output space has been provided
00256   before the call.)  Flushing may degrade compression for some compression
00257   algorithms and so it should be used only when necessary.
00258 
00259     If flush is set to Z_FULL_FLUSH, all output is flushed as with
00260   Z_SYNC_FLUSH, and the compression state is reset so that decompression can
00261   restart from this point if previous compressed data has been damaged or if
00262   random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
00263   the compression.
00264 
00265     If deflate returns with avail_out == 0, this function must be called again
00266   with the same value of the flush parameter and more output space (updated
00267   avail_out), until the flush is complete (deflate returns with non-zero
00268   avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
00269   avail_out is greater than six to avoid repeated flush markers due to
00270   avail_out == 0 on return.
00271 
00272     If the parameter flush is set to Z_FINISH, pending input is processed,
00273   pending output is flushed and deflate returns with Z_STREAM_END if there
00274   was enough output space; if deflate returns with Z_OK, this function must be
00275   called again with Z_FINISH and more output space (updated avail_out) but no
00276   more input data, until it returns with Z_STREAM_END or an error. After
00277   deflate has returned Z_STREAM_END, the only possible operations on the
00278   stream are deflateReset or deflateEnd.
00279 
00280     Z_FINISH can be used immediately after deflateInit if all the compression
00281   is to be done in a single step. In this case, avail_out must be at least
00282   the value returned by deflateBound (see below). If deflate does not return
00283   Z_STREAM_END, then it must be called again as described above.
00284 
00285     deflate() sets strm->adler to the adler32 checksum of all input read
00286   so far (that is, total_in bytes).
00287 
00288     deflate() may update data_type if it can make a good guess about
00289   the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
00290   binary. This field is only for information purposes and does not affect
00291   the compression algorithm in any manner.
00292 
00293     deflate() returns Z_OK if some progress has been made (more input
00294   processed or more output produced), Z_STREAM_END if all input has been
00295   consumed and all output has been produced (only when flush is set to
00296   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
00297   if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
00298   (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
00299   fatal, and deflate() can be called again with more input and more output
00300   space to continue compressing.
00301 */
00302 
00303 
00304 ZEXTERN INT32 ZEXPORT deflateEnd OF((z_streamp strm));
00305 /*
00306      All dynamically allocated data structures for this stream are freed.
00307    This function discards any unprocessed input and does not flush any
00308    pending output.
00309 
00310      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
00311    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
00312    prematurely (some input or output was discarded). In the error case,
00313    msg may be set but then points to a static string (which must not be
00314    deallocated).
00315 */
00316 
00317 
00318 /*
00319 ZEXTERN INT32 ZEXPORT inflateInit OF((z_streamp strm));
00320 
00321      Initializes the internal stream state for decompression. The fields
00322    next_in, avail_in, zalloc, zfree and opaque must be initialized before by
00323    the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
00324    value depends on the compression method), inflateInit determines the
00325    compression method from the zlib header and allocates all data structures
00326    accordingly; otherwise the allocation will be deferred to the first call of
00327    inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
00328    use default allocation functions.
00329 
00330      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
00331    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
00332    version assumed by the caller.  msg is set to null if there is no error
00333    message. inflateInit does not perform any decompression apart from reading
00334    the zlib header if present: this will be done by inflate().  (So next_in and
00335    avail_in may be modified, but next_out and avail_out are unchanged.)
00336 */
00337 
00338 
00339 ZEXTERN INT32 ZEXPORT inflate OF((z_streamp strm, INT32 flush));
00340 /*
00341     inflate decompresses as much data as possible, and stops when the input
00342   buffer becomes empty or the output buffer becomes full. It may introduce
00343   some output latency (reading input without producing any output) except when
00344   forced to flush.
00345 
00346   The detailed semantics are as follows. inflate performs one or both of the
00347   following actions:
00348 
00349   - Decompress more input starting at next_in and update next_in and avail_in
00350     accordingly. If not all input can be processed (because there is not
00351     enough room in the output buffer), next_in is updated and processing
00352     will resume at this point for the next call of inflate().
00353 
00354   - Provide more output starting at next_out and update next_out and avail_out
00355     accordingly.  inflate() provides as much output as possible, until there
00356     is no more input data or no more space in the output buffer (see below
00357     about the flush parameter).
00358 
00359   Before the call of inflate(), the application should ensure that at least
00360   one of the actions is possible, by providing more input and/or consuming
00361   more output, and updating the next_* and avail_* values accordingly.
00362   The application can consume the uncompressed output when it wants, for
00363   example when the output buffer is full (avail_out == 0), or after each
00364   call of inflate(). If inflate returns Z_OK and with zero avail_out, it
00365   must be called again after making room in the output buffer because there
00366   might be more output pending.
00367 
00368     The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
00369   Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
00370   output as possible to the output buffer. Z_BLOCK requests that inflate() stop
00371   if and when it get to the next deflate block boundary. When decoding the zlib
00372   or gzip format, this will cause inflate() to return immediately after the
00373   header and before the first block. When doing a raw inflate, inflate() will
00374   go ahead and process the first block, and will return when it gets to the end
00375   of that block, or when it runs out of data.
00376 
00377     The Z_BLOCK option assists in appending to or combining deflate streams.
00378   Also to assist in this, on return inflate() will set strm->data_type to the
00379   number of unused bits in the last byte taken from strm->next_in, plus 64
00380   if inflate() is currently decoding the last block in the deflate stream,
00381   plus 128 if inflate() returned immediately after decoding an end-of-block
00382   code or decoding the complete header up to just before the first byte of the
00383   deflate stream. The end-of-block will not be indicated until all of the
00384   uncompressed data from that block has been written to strm->next_out.  The
00385   number of unused bits may in general be greater than seven, except when
00386   bit 7 of data_type is set, in which case the number of unused bits will be
00387   less than eight.
00388 
00389     inflate() should normally be called until it returns Z_STREAM_END or an
00390   error. However if all decompression is to be performed in a single step
00391   (a single call of inflate), the parameter flush should be set to
00392   Z_FINISH. In this case all pending input is processed and all pending
00393   output is flushed; avail_out must be large enough to hold all the
00394   uncompressed data. (The size of the uncompressed data may have been saved
00395   by the compressor for this purpose.) The next operation on this stream must
00396   be inflateEnd to deallocate the decompression state. The use of Z_FINISH
00397   is never required, but can be used to inform inflate that a faster approach
00398   may be used for the single inflate() call.
00399 
00400      In this implementation, inflate() always flushes as much output as
00401   possible to the output buffer, and always uses the faster approach on the
00402   first call. So the only effect of the flush parameter in this implementation
00403   is on the return value of inflate(), as noted below, or when it returns early
00404   because Z_BLOCK is used.
00405 
00406      If a preset dictionary is needed after this call (see inflateSetDictionary
00407   below), inflate sets strm->adler to the adler32 checksum of the dictionary
00408   chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
00409   strm->adler to the adler32 checksum of all output produced so far (that is,
00410   total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
00411   below. At the end of the stream, inflate() checks that its computed adler32
00412   checksum is equal to that saved by the compressor and returns Z_STREAM_END
00413   only if the checksum is correct.
00414 
00415     inflate() will decompress and check either zlib-wrapped or gzip-wrapped
00416   deflate data.  The header type is detected automatically.  Any information
00417   contained in the gzip header is not retained, so applications that need that
00418   information should instead use raw inflate, see inflateInit2() below, or
00419   inflateBack() and perform their own processing of the gzip header and
00420   trailer.
00421 
00422     inflate() returns Z_OK if some progress has been made (more input processed
00423   or more output produced), Z_STREAM_END if the end of the compressed data has
00424   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
00425   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
00426   corrupted (input stream not conforming to the zlib format or incorrect check
00427   value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
00428   if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
00429   Z_BUF_ERROR if no progress is possible or if there was not enough room in the
00430   output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
00431   inflate() can be called again with more input and more output space to
00432   continue decompressing. If Z_DATA_ERROR is returned, the application may then
00433   call inflateSync() to look for a good compression block if a partial recovery
00434   of the data is desired.
00435 */
00436 
00437 
00438 ZEXTERN INT32 ZEXPORT inflateEnd OF((z_streamp strm));
00439 /*
00440      All dynamically allocated data structures for this stream are freed.
00441    This function discards any unprocessed input and does not flush any
00442    pending output.
00443 
00444      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
00445    was inconsistent. In the error case, msg may be set but then points to a
00446    static string (which must not be deallocated).
00447 */
00448 
00449                         /* Advanced functions */
00450 
00451 /*
00452     The following functions are needed only in some special applications.
00453 */
00454 
00455 /*
00456 ZEXTERN INT32 ZEXPORT deflateInit2 OF((z_streamp strm,
00457                                      INT32  level,
00458                                      INT32  method,
00459                                      INT32  windowBits,
00460                                      INT32  memLevel,
00461                                      INT32  strategy));
00462 
00463      This is another version of deflateInit with more compression options. The
00464    fields next_in, zalloc, zfree and opaque must be initialized before by
00465    the caller.
00466 
00467      The method parameter is the compression method. It must be Z_DEFLATED in
00468    this version of the library.
00469 
00470      The windowBits parameter is the base two logarithm of the window size
00471    (the size of the history buffer). It should be in the range 8..15 for this
00472    version of the library. Larger values of this parameter result in better
00473    compression at the expense of memory usage. The default value is 15 if
00474    deflateInit is used instead.
00475 
00476      windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
00477    determines the window size. deflate() will then generate raw deflate data
00478    with no zlib header or trailer, and will not compute an adler32 check value.
00479 
00480      windowBits can also be greater than 15 for optional gzip encoding. Add
00481    16 to windowBits to write a simple gzip header and trailer around the
00482    compressed data instead of a zlib wrapper. The gzip header will have no
00483    file name, no extra data, no comment, no modification time (set to zero),
00484    no header crc, and the operating system will be set to 255 (unknown).  If a
00485    gzip stream is being written, strm->adler is a crc32 instead of an adler32.
00486 
00487      The memLevel parameter specifies how much memory should be allocated
00488    for the internal compression state. memLevel=1 uses minimum memory but
00489    is slow and reduces compression ratio; memLevel=9 uses maximum memory
00490    for optimal speed. The default value is 8. See zconf.h for total memory
00491    usage as a function of windowBits and memLevel.
00492 
00493      The strategy parameter is used to tune the compression algorithm. Use the
00494    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
00495    filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
00496    string match), or Z_RLE to limit match distances to one (run-length
00497    encoding). Filtered data consists mostly of small values with a somewhat
00498    random distribution. In this case, the compression algorithm is tuned to
00499    compress them better. The effect of Z_FILTERED is to force more Huffman
00500    coding and less string matching; it is somewhat intermediate between
00501    Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
00502    Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
00503    parameter only affects the compression ratio but not the correctness of the
00504    compressed output even if it is not set appropriately.
00505 
00506       deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
00507    memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
00508    method). msg is set to null if there is no error message.  deflateInit2 does
00509    not perform any compression: this will be done by deflate().
00510 */
00511 
00512 ZEXTERN INT32 ZEXPORT deflateSetDictionary OF((z_streamp strm,
00513                                              const Bytef *dictionary,
00514                                              uInt  dictLength));
00515 /*
00516      Initializes the compression dictionary from the given byte sequence
00517    without producing any compressed output. This function must be called
00518    immediately after deflateInit, deflateInit2 or deflateReset, before any
00519    call of deflate. The compressor and decompressor must use exactly the same
00520    dictionary (see inflateSetDictionary).
00521 
00522      The dictionary should consist of strings (byte sequences) that are likely
00523    to be encountered later in the data to be compressed, with the most commonly
00524    used strings preferably put towards the end of the dictionary. Using a
00525    dictionary is most useful when the data to be compressed is short and can be
00526    predicted with good accuracy; the data can then be compressed better than
00527    with the default empty dictionary.
00528 
00529      Depending on the size of the compression data structures selected by
00530    deflateInit or deflateInit2, a part of the dictionary may in effect be
00531    discarded, for example if the dictionary is larger than the window size in
00532    deflate or deflate2. Thus the strings most likely to be useful should be
00533    put at the end of the dictionary, not at the front.
00534 
00535      Upon return of this function, strm->adler is set to the adler32 value
00536    of the dictionary; the decompressor may later use this value to determine
00537    which dictionary has been used by the compressor. (The adler32 value
00538    applies to the whole dictionary even if only a subset of the dictionary is
00539    actually used by the compressor.) If a raw deflate was requested, then the
00540    adler32 value is not computed and strm->adler is not set.
00541 
00542      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
00543    parameter is invalid (such as NULL dictionary) or the stream state is
00544    inconsistent (for example if deflate has already been called for this stream
00545    or if the compression method is bsort). deflateSetDictionary does not
00546    perform any compression: this will be done by deflate().
00547 */
00548 
00549 ZEXTERN INT32 ZEXPORT deflateCopy OF((z_streamp dest,
00550                                     z_streamp source));
00551 /*
00552      Sets the destination stream as a complete copy of the source stream.
00553 
00554      This function can be useful when several compression strategies will be
00555    tried, for example when there are several ways of pre-processing the input
00556    data with a filter. The streams that will be discarded should then be freed
00557    by calling deflateEnd.  Note that deflateCopy duplicates the internal
00558    compression state which can be quite large, so this strategy is slow and
00559    can consume lots of memory.
00560 
00561      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
00562    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
00563    (such as zalloc being NULL). msg is left unchanged in both source and
00564    destination.
00565 */
00566 
00567 ZEXTERN INT32 ZEXPORT deflateReset OF((z_streamp strm));
00568 /*
00569      This function is equivalent to deflateEnd followed by deflateInit,
00570    but does not free and reallocate all the internal compression state.
00571    The stream will keep the same compression level and any other attributes
00572    that may have been set by deflateInit2.
00573 
00574       deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
00575    stream state was inconsistent (such as zalloc or state being NULL).
00576 */
00577 
00578 ZEXTERN INT32 ZEXPORT deflateParams OF((z_streamp strm,
00579                                       INT32 level,
00580                                       INT32 strategy));
00581 /*
00582      Dynamically update the compression level and compression strategy.  The
00583    interpretation of level and strategy is as in deflateInit2.  This can be
00584    used to switch between compression and straight copy of the input data, or
00585    to switch to a different kind of input data requiring a different
00586    strategy. If the compression level is changed, the input available so far
00587    is compressed with the old level (and may be flushed); the new level will
00588    take effect only at the next call of deflate().
00589 
00590      Before the call of deflateParams, the stream state must be set as for
00591    a call of deflate(), since the currently available input may have to
00592    be compressed and flushed. In particular, strm->avail_out must be non-zero.
00593 
00594      deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
00595    stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
00596    if strm->avail_out was zero.
00597 */
00598 
00599 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
00600                                        uLong sourceLen));
00601 /*
00602      deflateBound() returns an upper bound on the compressed size after
00603    deflation of sourceLen bytes.  It must be called after deflateInit()
00604    or deflateInit2().  This would be used to allocate an output buffer
00605    for deflation in a single pass, and so would be called before deflate().
00606 */
00607 
00608 ZEXTERN INT32 ZEXPORT deflatePrime OF((z_streamp strm,
00609                                      INT32 bits,
00610                                      INT32 value));
00611 /*
00612      deflatePrime() inserts bits in the deflate output stream.  The intent
00613   is that this function is used to start off the deflate output with the
00614   bits leftover from a previous deflate stream when appending to it.  As such,
00615   this function can only be used for raw deflate, and must be used before the
00616   first deflate() call after a deflateInit2() or deflateReset().  bits must be
00617   less than or equal to 16, and that many of the least significant bits of
00618   value will be inserted in the output.
00619 
00620       deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
00621    stream state was inconsistent.
00622 */
00623 
00624 /*
00625 ZEXTERN INT32 ZEXPORT inflateInit2 OF((z_streamp strm,
00626                                      INT32  windowBits));
00627 
00628      This is another version of inflateInit with an extra parameter. The
00629    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
00630    before by the caller.
00631 
00632      The windowBits parameter is the base two logarithm of the maximum window
00633    size (the size of the history buffer).  It should be in the range 8..15 for
00634    this version of the library. The default value is 15 if inflateInit is used
00635    instead. windowBits must be greater than or equal to the windowBits value
00636    provided to deflateInit2() while compressing, or it must be equal to 15 if
00637    deflateInit2() was not used. If a compressed stream with a larger window
00638    size is given as input, inflate() will return with the error code
00639    Z_DATA_ERROR instead of trying to allocate a larger window.
00640 
00641      windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
00642    determines the window size. inflate() will then process raw deflate data,
00643    not looking for a zlib or gzip header, not generating a check value, and not
00644    looking for any check values for comparison at the end of the stream. This
00645    is for use with other formats that use the deflate compressed data format
00646    such as zip.  Those formats provide their own check values. If a custom
00647    format is developed using the raw deflate format for compressed data, it is
00648    recommended that a check value such as an adler32 or a crc32 be applied to
00649    the uncompressed data as is done in the zlib, gzip, and zip formats.  For
00650    most applications, the zlib format should be used as is. Note that comments
00651    above on the use in deflateInit2() applies to the magnitude of windowBits.
00652 
00653      windowBits can also be greater than 15 for optional gzip decoding. Add
00654    32 to windowBits to enable zlib and gzip decoding with automatic header
00655    detection, or add 16 to decode only the gzip format (the zlib format will
00656    return a Z_DATA_ERROR.  If a gzip stream is being decoded, strm->adler is
00657    a crc32 instead of an adler32.
00658 
00659      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
00660    memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
00661    memLevel). msg is set to null if there is no error message.  inflateInit2
00662    does not perform any decompression apart from reading the zlib header if
00663    present: this will be done by inflate(). (So next_in and avail_in may be
00664    modified, but next_out and avail_out are unchanged.)
00665 */
00666 
00667 ZEXTERN INT32 ZEXPORT inflateSetDictionary OF((z_streamp strm,
00668                                              const Bytef *dictionary,
00669                                              uInt  dictLength));
00670 /*
00671      Initializes the decompression dictionary from the given uncompressed byte
00672    sequence. This function must be called immediately after a call of inflate
00673    if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
00674    can be determined from the adler32 value returned by this call of
00675    inflate. The compressor and decompressor must use exactly the same
00676    dictionary (see deflateSetDictionary).
00677 
00678      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
00679    parameter is invalid (such as NULL dictionary) or the stream state is
00680    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
00681    expected one (incorrect adler32 value). inflateSetDictionary does not
00682    perform any decompression: this will be done by subsequent calls of
00683    inflate().
00684 */
00685 
00686 ZEXTERN INT32 ZEXPORT inflateSync OF((z_streamp strm));
00687 /*
00688     Skips invalid compressed data until a full flush point (see above the
00689   description of deflate with Z_FULL_FLUSH) can be found, or until all
00690   available input is skipped. No output is provided.
00691 
00692     inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
00693   if no more input was provided, Z_DATA_ERROR if no flush point has been found,
00694   or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
00695   case, the application may save the current current value of total_in which
00696   indicates where valid compressed data was found. In the error case, the
00697   application may repeatedly call inflateSync, providing more input each time,
00698   until success or end of the input data.
00699 */
00700 
00701 ZEXTERN INT32 ZEXPORT inflateCopy OF((z_streamp dest,
00702                                     z_streamp source));
00703 /*
00704      Sets the destination stream as a complete copy of the source stream.
00705 
00706      This function can be useful when randomly accessing a large stream.  The
00707    first pass through the stream can periodically record the inflate state,
00708    allowing restarting inflate at those points when randomly accessing the
00709    stream.
00710 
00711      inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
00712    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
00713    (such as zalloc being NULL). msg is left unchanged in both source and
00714    destination.
00715 */
00716 
00717 ZEXTERN INT32 ZEXPORT inflateReset OF((z_streamp strm));
00718 /*
00719      This function is equivalent to inflateEnd followed by inflateInit,
00720    but does not free and reallocate all the internal decompression state.
00721    The stream will keep attributes that may have been set by inflateInit2.
00722 
00723       inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
00724    stream state was inconsistent (such as zalloc or state being NULL).
00725 */
00726 
00727 /*
00728 ZEXTERN INT32 ZEXPORT inflateBackInit OF((z_stream FAR *strm, INT32 windowBits,
00729                                         unsigned char FAR *window));
00730 
00731      Initialize the internal stream state for decompression using inflateBack()
00732    calls.  The fields zalloc, zfree and opaque in strm must be initialized
00733    before the call.  If zalloc and zfree are Z_NULL, then the default library-
00734    derived memory allocation routines are used.  windowBits is the base two
00735    logarithm of the window size, in the range 8..15.  window is a caller
00736    supplied buffer of that size.  Except for special applications where it is
00737    assured that deflate was used with small window sizes, windowBits must be 15
00738    and a 32K byte window must be supplied to be able to decompress general
00739    deflate streams.
00740 
00741      See inflateBack() for the usage of these routines.
00742 
00743      inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
00744    the paramaters are invalid, Z_MEM_ERROR if the internal state could not
00745    be allocated, or Z_VERSION_ERROR if the version of the library does not
00746    match the version of the header file.
00747 */
00748 
00749 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
00750 typedef INT32 (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
00751 
00752 ZEXTERN INT32 ZEXPORT inflateBack OF((z_stream FAR *strm,
00753                                     in_func in, void FAR *in_desc,
00754                                     out_func out, void FAR *out_desc));
00755 /*
00756      inflateBack() does a raw inflate with a single call using a call-back
00757    interface for input and output.  This is more efficient than inflate() for
00758    file i/o applications in that it avoids copying between the output and the
00759    sliding window by simply making the window itself the output buffer.  This
00760    function trusts the application to not change the output buffer passed by
00761    the output function, at least until inflateBack() returns.
00762 
00763      inflateBackInit() must be called first to allocate the internal state
00764    and to initialize the state with the user-provided window buffer.
00765    inflateBack() may then be used multiple times to inflate a complete, raw
00766    deflate stream with each call.  inflateBackEnd() is then called to free
00767    the allocated state.
00768 
00769      A raw deflate stream is one with no zlib or gzip header or trailer.
00770    This routine would normally be used in a utility that reads zip or gzip
00771    files and writes out uncompressed files.  The utility would decode the
00772    header and process the trailer on its own, hence this routine expects
00773    only the raw deflate stream to decompress.  This is different from the
00774    normal behavior of inflate(), which expects either a zlib or gzip header and
00775    trailer around the deflate stream.
00776 
00777      inflateBack() uses two subroutines supplied by the caller that are then
00778    called by inflateBack() for input and output.  inflateBack() calls those
00779    routines until it reads a complete deflate stream and writes out all of the
00780    uncompressed data, or until it encounters an error.  The function's
00781    parameters and return types are defined above in the in_func and out_func
00782    typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
00783    number of bytes of provided input, and a pointer to that input in buf.  If
00784    there is no input available, in() must return zero--buf is ignored in that
00785    case--and inflateBack() will return a buffer error.  inflateBack() will call
00786    out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].  out()
00787    should return zero on success, or non-zero on failure.  If out() returns
00788    non-zero, inflateBack() will return with an error.  Neither in() nor out()
00789    are permitted to change the contents of the window provided to
00790    inflateBackInit(), which is also the buffer that out() uses to write from.
00791    The length written by out() will be at most the window size.  Any non-zero
00792    amount of input may be provided by in().
00793 
00794      For convenience, inflateBack() can be provided input on the first call by
00795    setting strm->next_in and strm->avail_in.  If that input is exhausted, then
00796    in() will be called.  Therefore strm->next_in must be initialized before
00797    calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
00798    immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
00799    must also be initialized, and then if strm->avail_in is not zero, input will
00800    initially be taken from strm->next_in[0 .. strm->avail_in - 1].
00801 
00802      The in_desc and out_desc parameters of inflateBack() is passed as the
00803    first parameter of in() and out() respectively when they are called.  These
00804    descriptors can be optionally used to pass any information that the caller-
00805    supplied in() and out() functions need to do their job.
00806 
00807      On return, inflateBack() will set strm->next_in and strm->avail_in to
00808    pass back any unused input that was provided by the last in() call.  The
00809    return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
00810    if in() or out() returned an error, Z_DATA_ERROR if there was a format
00811    error in the deflate stream (in which case strm->msg is set to indicate the
00812    nature of the error), or Z_STREAM_ERROR if the stream was not properly
00813    initialized.  In the case of Z_BUF_ERROR, an input or output error can be
00814    distinguished using strm->next_in which will be Z_NULL only if in() returned
00815    an error.  If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
00816    out() returning non-zero.  (in() will always be called before out(), so
00817    strm->next_in is assured to be defined if out() returns non-zero.)  Note
00818    that inflateBack() cannot return Z_OK.
00819 */
00820 
00821 ZEXTERN INT32 ZEXPORT inflateBackEnd OF((z_stream FAR *strm));
00822 /*
00823      All memory allocated by inflateBackInit() is freed.
00824 
00825      inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
00826    state was inconsistent.
00827 */
00828 
00829 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
00830 /* Return flags indicating compile-time options.
00831 
00832     Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
00833      1.0: size of uInt
00834      3.2: size of uLong
00835      5.4: size of voidpf (pointer)
00836      7.6: size of z_off_t
00837 
00838     Compiler, assembler, and debug options:
00839      8: DEBUG
00840      9: ASMV or ASMINF -- use ASM code
00841      10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
00842      11: 0 (reserved)
00843 
00844     One-time table building (smaller code, but not thread-safe if true):
00845      12: BUILDFIXED -- build static block decoding tables when needed
00846      13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
00847      14,15: 0 (reserved)
00848 
00849     Library content (indicates missing functionality):
00850      16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
00851                           deflate code when not needed)
00852      17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
00853                     and decode gzip streams (to avoid linking crc code)
00854      18-19: 0 (reserved)
00855 
00856     Operation variations (changes in library functionality):
00857      20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
00858      21: FASTEST -- deflate algorithm with only one, lowest compression level
00859      22,23: 0 (reserved)
00860 
00861     The sprintf variant used by gzprintf (zero is best):
00862      24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
00863      25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
00864      26: 0 = returns value, 1 = void -- 1 means inferred string length returned
00865 
00866     Remainder:
00867      27-31: 0 (reserved)
00868  */
00869 
00870 
00871                         /* utility functions */
00872 
00873 /*
00874      The following utility functions are implemented on top of the
00875    basic stream-oriented functions. To simplify the interface, some
00876    default options are assumed (compression level and memory usage,
00877    standard memory allocation functions). The source code of these
00878    utility functions can easily be modified if you need special options.
00879 */
00880 
00881 ZEXTERN INT32 ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
00882                                  const Bytef *source, uLong sourceLen));
00883 /*
00884      Compresses the source buffer into the destination buffer.  sourceLen is
00885    the byte length of the source buffer. Upon entry, destLen is the total
00886    size of the destination buffer, which must be at least the value returned
00887    by compressBound(sourceLen). Upon exit, destLen is the actual size of the
00888    compressed buffer.
00889      This function can be used to compress a whole file at once if the
00890    input file is mmap'ed.
00891      compress returns Z_OK if success, Z_MEM_ERROR if there was not
00892    enough memory, Z_BUF_ERROR if there was not enough room in the output
00893    buffer.
00894 */
00895 
00896 ZEXTERN INT32 ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
00897                                   const Bytef *source, uLong sourceLen,
00898                                   INT32 level));
00899 /*
00900      Compresses the source buffer into the destination buffer. The level
00901    parameter has the same meaning as in deflateInit.  sourceLen is the byte
00902    length of the source buffer. Upon entry, destLen is the total size of the
00903    destination buffer, which must be at least the value returned by
00904    compressBound(sourceLen). Upon exit, destLen is the actual size of the
00905    compressed buffer.
00906 
00907      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
00908    memory, Z_BUF_ERROR if there was not enough room in the output buffer,
00909    Z_STREAM_ERROR if the level parameter is invalid.
00910 */
00911 
00912 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
00913 /*
00914      compressBound() returns an upper bound on the compressed size after
00915    compress() or compress2() on sourceLen bytes.  It would be used before
00916    a compress() or compress2() call to allocate the destination buffer.
00917 */
00918 
00919 ZEXTERN INT32 ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
00920                                    const Bytef *source, uLong sourceLen));
00921 /*
00922      Decompresses the source buffer into the destination buffer.  sourceLen is
00923    the byte length of the source buffer. Upon entry, destLen is the total
00924    size of the destination buffer, which must be large enough to hold the
00925    entire uncompressed data. (The size of the uncompressed data must have
00926    been saved previously by the compressor and transmitted to the decompressor
00927    by some mechanism outside the scope of this compression library.)
00928    Upon exit, destLen is the actual size of the compressed buffer.
00929      This function can be used to decompress a whole file at once if the
00930    input file is mmap'ed.
00931 
00932      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
00933    enough memory, Z_BUF_ERROR if there was not enough room in the output
00934    buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
00935 */
00936 
00937 
00938 typedef voidp gzFile;
00939 
00940 ZEXTERN gzFile ZEXPORT gzopen  OF((const char *path, const char *mode));
00941 /*
00942      Opens a gzip (.gz) file for reading or writing. The mode parameter
00943    is as in fopen ("rb" or "wb") but can also include a compression level
00944    ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
00945    Huffman only compression as in "wb1h", or 'R' for run-length encoding
00946    as in "wb1R". (See the description of deflateInit2 for more information
00947    about the strategy parameter.)
00948 
00949      gzopen can be used to read a file which is not in gzip format; in this
00950    case gzread will directly read from the file without decompression.
00951 
00952      gzopen returns NULL if the file could not be opened or if there was
00953    insufficient memory to allocate the (de)compression state; errno
00954    can be checked to distinguish the two cases (if errno is zero, the
00955    zlib error is Z_MEM_ERROR).  */
00956 
00957 ZEXTERN gzFile ZEXPORT gzdopen  OF((INT32 fd, const char *mode));
00958 /*
00959      gzdopen() associates a gzFile with the file descriptor fd.  File
00960    descriptors are obtained from calls like open, dup, creat, pipe or
00961    fileno (in the file has been previously opened with fopen).
00962    The mode parameter is as in gzopen.
00963      The next call of gzclose on the returned gzFile will also close the
00964    file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
00965    descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
00966      gzdopen returns NULL if there was insufficient memory to allocate
00967    the (de)compression state.
00968 */
00969 
00970 ZEXTERN INT32 ZEXPORT gzsetparams OF((gzFile file, INT32 level, INT32 strategy));
00971 /*
00972      Dynamically update the compression level or strategy. See the description
00973    of deflateInit2 for the meaning of these parameters.
00974      gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
00975    opened for writing.
00976 */
00977 
00978 ZEXTERN INT32 ZEXPORT    gzread  OF((gzFile file, voidp buf, unsigned len));
00979 /*
00980      Reads the given number of uncompressed bytes from the compressed file.
00981    If the input file was not in gzip format, gzread copies the given number
00982    of bytes into the buffer.
00983      gzread returns the number of uncompressed bytes actually read (0 for
00984    end of file, -1 for error). */
00985 
00986 ZEXTERN INT32 ZEXPORT    gzwrite OF((gzFile file,
00987                                    voidpc buf, unsigned len));
00988 /*
00989      Writes the given number of uncompressed bytes into the compressed file.
00990    gzwrite returns the number of uncompressed bytes actually written
00991    (0 in case of error).
00992 */
00993 
00994 ZEXTERN INT32 ZEXPORTVA   gzprintf OF((gzFile file, const char *format, ...));
00995 /*
00996      Converts, formats, and writes the args to the compressed file under
00997    control of the format string, as in fprintf. gzprintf returns the number of
00998    uncompressed bytes actually written (0 in case of error).  The number of
00999    uncompressed bytes written is limited to 4095. The caller should assure that
01000    this limit is not exceeded. If it is exceeded, then gzprintf() will return
01001    return an error (0) with nothing written. In this case, there may also be a
01002    buffer overflow with unpredictable consequences, which is possible only if
01003    zlib was compiled with the insecure functions sprintf() or vsprintf()
01004    because the secure snprintf() or vsnprintf() functions were not available.
01005 */
01006 
01007 ZEXTERN INT32 ZEXPORT gzputs OF((gzFile file, const char *s));
01008 /*
01009       Writes the given null-terminated string to the compressed file, excluding
01010    the terminating null character.
01011       gzputs returns the number of characters written, or -1 in case of error.
01012 */
01013 
01014 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, INT32 len));
01015 /*
01016       Reads bytes from the compressed file until len-1 characters are read, or
01017    a newline character is read and transferred to buf, or an end-of-file
01018    condition is encountered.  The string is then terminated with a null
01019    character.
01020       gzgets returns buf, or Z_NULL in case of error.
01021 */
01022 
01023 ZEXTERN INT32 ZEXPORT    gzputc OF((gzFile file, INT32 c));
01024 /*
01025       Writes c, converted to an unsigned char, into the compressed file.
01026    gzputc returns the value that was written, or -1 in case of error.
01027 */
01028 
01029 ZEXTERN INT32 ZEXPORT    gzgetc OF((gzFile file));
01030 /*
01031       Reads one byte from the compressed file. gzgetc returns this byte
01032    or -1 in case of end of file or error.
01033 */
01034 
01035 ZEXTERN INT32 ZEXPORT    gzungetc OF((INT32 c, gzFile file));
01036 /*
01037       Push one character back onto the stream to be read again later.
01038    Only one character of push-back is allowed.  gzungetc() returns the
01039    character pushed, or -1 on failure.  gzungetc() will fail if a
01040    character has been pushed but not read yet, or if c is -1. The pushed
01041    character will be discarded if the stream is repositioned with gzseek()
01042    or gzrewind().
01043 */
01044 
01045 ZEXTERN INT32 ZEXPORT    gzflush OF((gzFile file, INT32 flush));
01046 /*
01047      Flushes all pending output into the compressed file. The parameter
01048    flush is as in the deflate() function. The return value is the zlib
01049    error number (see function gzerror below). gzflush returns Z_OK if
01050    the flush parameter is Z_FINISH and all output could be flushed.
01051      gzflush should be called only when strictly necessary because it can
01052    degrade compression.
01053 */
01054 
01055 ZEXTERN z_off_t ZEXPORT    gzseek OF((gzFile file,
01056                                       z_off_t offset, INT32 whence));
01057 /*
01058       Sets the starting position for the next gzread or gzwrite on the
01059    given compressed file. The offset represents a number of bytes in the
01060    uncompressed data stream. The whence parameter is defined as in lseek(2);
01061    the value SEEK_END is not supported.
01062      If the file is opened for reading, this function is emulated but can be
01063    extremely slow. If the file is opened for writing, only forward seeks are
01064    supported; gzseek then compresses a sequence of zeroes up to the new
01065    starting position.
01066 
01067       gzseek returns the resulting offset location as measured in bytes from
01068    the beginning of the uncompressed stream, or -1 in case of error, in
01069    particular if the file is opened for writing and the new starting position
01070    would be before the current position.
01071 */
01072 
01073 ZEXTERN INT32 ZEXPORT    gzrewind OF((gzFile file));
01074 /*
01075      Rewinds the given file. This function is supported only for reading.
01076 
01077    gzrewind(file) is equivalent to (INT32)gzseek(file, 0L, SEEK_SET)
01078 */
01079 
01080 ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
01081 /*
01082      Returns the starting position for the next gzread or gzwrite on the
01083    given compressed file. This position represents a number of bytes in the
01084    uncompressed data stream.
01085 
01086    gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
01087 */
01088 
01089 ZEXTERN INT32 ZEXPORT gzeof OF((gzFile file));
01090 /*
01091      Returns 1 when EOF has previously been detected reading the given
01092    input stream, otherwise zero.
01093 */
01094 
01095 ZEXTERN INT32 ZEXPORT    gzclose OF((gzFile file));
01096 /*
01097      Flushes all pending output if necessary, closes the compressed file
01098    and deallocates all the (de)compression state. The return value is the zlib
01099    error number (see function gzerror below).
01100 */
01101 
01102 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, INT32 *errnum));
01103 /*
01104      Returns the error message for the last error which occurred on the
01105    given compressed file. errnum is set to zlib error number. If an
01106    error occurred in the file system and not in the compression library,
01107    errnum is set to Z_ERRNO and the application may consult errno
01108    to get the exact error code.
01109 */
01110 
01111 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
01112 /*
01113      Clears the error and end-of-file flags for file. This is analogous to the
01114    clearerr() function in stdio. This is useful for continuing to read a gzip
01115    file that is being written concurrently.
01116 */
01117 
01118                         /* checksum functions */
01119 
01120 /*
01121      These functions are not related to compression but are exported
01122    anyway because they might be useful in applications using the
01123    compression library.
01124 */
01125 
01126 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
01127 
01128 /*
01129      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
01130    return the updated checksum. If buf is NULL, this function returns
01131    the required initial value for the checksum.
01132    An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
01133    much faster. Usage example:
01134 
01135      uLong adler = adler32(0L, Z_NULL, 0);
01136 
01137      while (read_buffer(buffer, length) != EOF) {
01138        adler = adler32(adler, buffer, length);
01139      }
01140      if (adler != original_adler) error();
01141 */
01142 
01143 ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
01144 /*
01145      Update a running crc with the bytes buf[0..len-1] and return the updated
01146    crc. If buf is NULL, this function returns the required initial value
01147    for the crc. Pre- and post-conditioning (one's complement) is performed
01148    within this function so it shouldn't be done by the application.
01149    Usage example:
01150 
01151      uLong crc = crc32(0L, Z_NULL, 0);
01152 
01153      while (read_buffer(buffer, length) != EOF) {
01154        crc = crc32(crc, buffer, length);
01155      }
01156      if (crc != original_crc) error();
01157 */
01158 
01159 
01160                         /* various hacks, don't look :) */
01161 
01162 /* deflateInit and inflateInit are macros to allow checking the zlib version
01163  * and the compiler's view of z_stream:
01164  */
01165 ZEXTERN INT32 ZEXPORT deflateInit_ OF((z_streamp strm, INT32 level,
01166                                      const char *version, INT32 stream_size));
01167 ZEXTERN INT32 ZEXPORT inflateInit_ OF((z_streamp strm,
01168                                      const char *version, INT32 stream_size));
01169 ZEXTERN INT32 ZEXPORT deflateInit2_ OF((z_streamp strm, INT32  level, INT32  method,
01170                                       INT32 windowBits, INT32 memLevel,
01171                                       INT32 strategy, const char *version,
01172                                       INT32 stream_size));
01173 ZEXTERN INT32 ZEXPORT inflateInit2_ OF((z_streamp strm, INT32  windowBits,
01174                                       const char *version, INT32 stream_size));
01175 ZEXTERN INT32 ZEXPORT inflateBackInit_ OF((z_stream FAR *strm, INT32 windowBits,
01176                                          unsigned char FAR *window,
01177                                          const char *version,
01178                                          INT32 stream_size));
01179 #define deflateInit(strm, level) \
01180         deflateInit_((strm), (level),       ZLIB_VERSION, sizeof(z_stream))
01181 #define inflateInit(strm) \
01182         inflateInit_((strm),                ZLIB_VERSION, sizeof(z_stream))
01183 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
01184         deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
01185                       (strategy),           ZLIB_VERSION, sizeof(z_stream))
01186 #define inflateInit2(strm, windowBits) \
01187         inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
01188 #define inflateBackInit(strm, windowBits, window) \
01189         inflateBackInit_((strm), (windowBits), (window), \
01190         ZLIB_VERSION, sizeof(z_stream))
01191 
01192 
01193 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
01194     struct internal_state {INT32 dummy;}; /* hack for buggy compilers */
01195 #endif
01196 
01197 ZEXTERN const char   * ZEXPORT zError           OF((INT32));
01198 ZEXTERN INT32            ZEXPORT inflateSyncPoint OF((z_streamp z));
01199 ZEXTERN const uLongf * ZEXPORT get_crc_table    OF((void));
01200 
01201 #ifdef __cplusplus
01202 }
01203 #endif
01204 
01205 #endif /* ZLIB_H */

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