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zlib.h
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00001 /* zlib.h -- interface of the 'zlib' general purpose compression library
00002   version 1.2.1, November 17th, 2003
00003 
00004   Copyright (C) 1995-2003 Jean-loup Gailly and Mark Adler
00005 
00006   This software is provided 'as-is', without any express or implied
00007   warranty.  In no event will the authors be held liable for any damages
00008   arising from the use of this software.
00009 
00010   Permission is granted to anyone to use this software for any purpose,
00011   including commercial applications, and to alter it and redistribute it
00012   freely, subject to the following restrictions:
00013 
00014   1. The origin of this software must not be misrepresented; you must not
00015      claim that you wrote the original software. If you use this software
00016      in a product, an acknowledgment in the product documentation would be
00017      appreciated but is not required.
00018   2. Altered source versions must be plainly marked as such, and must not be
00019      misrepresented as being the original software.
00020   3. This notice may not be removed or altered from any source distribution.
00021 
00022   Jean-loup Gailly        Mark Adler
00023   jloup@gzip.org          madler@alumni.caltech.edu
00024 
00025 
00026   The data format used by the zlib library is described by RFCs (Request for
00027   Comments) 1950 to 1952 in the files http://www.ietf.org/rfc/rfc1950.txt
00028   (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
00029 */
00030 
00031 #ifndef ZLIB_H
00032 #define ZLIB_H
00033 
00034 #include "zconf.h"
00035 
00036 #ifdef __cplusplus
00037 extern "C" {
00038 #endif
00039 
00040 #define ZLIB_VERSION "1.2.1"
00041 #define ZLIB_VERNUM 0x1210
00042 
00043 /*
00044      The 'zlib' compression library provides in-memory compression and
00045   decompression functions, including integrity checks of the uncompressed
00046   data.  This version of the library supports only one compression method
00047   (deflation) but other algorithms will be added later and will have the same
00048   stream interface.
00049 
00050      Compression can be done in a single step if the buffers are large
00051   enough (for example if an input file is mmap'ed), or can be done by
00052   repeated calls of the compression function.  In the latter case, the
00053   application must provide more input and/or consume the output
00054   (providing more output space) before each call.
00055 
00056      The compressed data format used by the in-memory functions is the zlib
00057   format, which is a zlib wrapper documented in RFC 1950, wrapped around a
00058   deflate stream, which is itself documented in RFC 1951.
00059 
00060      The library also supports reading and writing files in gzip (.gz) format
00061   with an interface similar to that of stdio using the functions that start
00062   with "gz".  The gzip format is different from the zlib format.  gzip is a
00063   gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
00064 
00065      The zlib format was designed to be compact and fast for use in memory
00066   and on communications channels.  The gzip format was designed for single-
00067   file compression on file systems, has a larger header than zlib to maintain
00068   directory information, and uses a different, slower check method than zlib.
00069 
00070      This library does not provide any functions to write gzip files in memory.
00071   However such functions could be easily written using zlib's deflate function,
00072   the documentation in the gzip RFC, and the examples in gzio.c.
00073 
00074      The library does not install any signal handler. The decoder checks
00075   the consistency of the compressed data, so the library should never
00076   crash even in case of corrupted input.
00077 */
00078 
00079 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
00080 typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
00081 
00082 struct internal_state;
00083 
00084 typedef struct z_stream_s {
00085     Bytef    *next_in;  /* next input byte */
00086     uInt     avail_in;  /* number of bytes available at next_in */
00087     uLong    total_in;  /* total nb of input bytes read so far */
00088 
00089     Bytef    *next_out; /* next output byte should be put there */
00090     uInt     avail_out; /* remaining free space at next_out */
00091     uLong    total_out; /* total nb of bytes output so far */
00092 
00093     char     *msg;      /* last error message, NULL if no error */
00094     struct internal_state FAR *state; /* not visible by applications */
00095 
00096     alloc_func zalloc;  /* used to allocate the internal state */
00097     free_func  zfree;   /* used to free the internal state */
00098     voidpf     opaque;  /* private data object passed to zalloc and zfree */
00099 
00100     int     data_type;  /* best guess about the data type: ascii or binary */
00101     uLong   adler;      /* adler32 value of the uncompressed data */
00102     uLong   reserved;   /* reserved for future use */
00103 } z_stream;
00104 
00105 typedef z_stream FAR *z_streamp;
00106 
00107 /*
00108    The application must update next_in and avail_in when avail_in has
00109    dropped to zero. It must update next_out and avail_out when avail_out
00110    has dropped to zero. The application must initialize zalloc, zfree and
00111    opaque before calling the init function. All other fields are set by the
00112    compression library and must not be updated by the application.
00113 
00114    The opaque value provided by the application will be passed as the first
00115    parameter for calls of zalloc and zfree. This can be useful for custom
00116    memory management. The compression library attaches no meaning to the
00117    opaque value.
00118 
00119    zalloc must return Z_NULL if there is not enough memory for the object.
00120    If zlib is used in a multi-threaded application, zalloc and zfree must be
00121    thread safe.
00122 
00123    On 16-bit systems, the functions zalloc and zfree must be able to allocate
00124    exactly 65536 bytes, but will not be required to allocate more than this
00125    if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
00126    pointers returned by zalloc for objects of exactly 65536 bytes *must*
00127    have their offset normalized to zero. The default allocation function
00128    provided by this library ensures this (see zutil.c). To reduce memory
00129    requirements and avoid any allocation of 64K objects, at the expense of
00130    compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
00131 
00132    The fields total_in and total_out can be used for statistics or
00133    progress reports. After compression, total_in holds the total size of
00134    the uncompressed data and may be saved for use in the decompressor
00135    (particularly if the decompressor wants to decompress everything in
00136    a single step).
00137 */
00138 
00139                         /* constants */
00140 
00141 #define Z_NO_FLUSH      0
00142 #define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
00143 #define Z_SYNC_FLUSH    2
00144 #define Z_FULL_FLUSH    3
00145 #define Z_FINISH        4
00146 #define Z_BLOCK         5
00147 /* Allowed flush values; see deflate() and inflate() below for details */
00148 
00149 #define Z_OK            0
00150 #define Z_STREAM_END    1
00151 #define Z_NEED_DICT     2
00152 #define Z_ERRNO        (-1)
00153 #define Z_STREAM_ERROR (-2)
00154 #define Z_DATA_ERROR   (-3)
00155 #define Z_MEM_ERROR    (-4)
00156 #define Z_BUF_ERROR    (-5)
00157 #define Z_VERSION_ERROR (-6)
00158 /* Return codes for the compression/decompression functions. Negative
00159  * values are errors, positive values are used for special but normal events.
00160  */
00161 
00162 #define Z_NO_COMPRESSION         0
00163 #define Z_BEST_SPEED             1
00164 #define Z_BEST_COMPRESSION       9
00165 #define Z_DEFAULT_COMPRESSION  (-1)
00166 /* compression levels */
00167 
00168 #define Z_FILTERED            1
00169 #define Z_HUFFMAN_ONLY        2
00170 #define Z_RLE                 3
00171 #define Z_DEFAULT_STRATEGY    0
00172 /* compression strategy; see deflateInit2() below for details */
00173 
00174 #define Z_BINARY   0
00175 #define Z_ASCII    1
00176 #define Z_UNKNOWN  2
00177 /* Possible values of the data_type field (though see inflate()) */
00178 
00179 #define Z_DEFLATED   8
00180 /* The deflate compression method (the only one supported in this version) */
00181 
00182 #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
00183 
00184 #define zlib_version zlibVersion()
00185 /* for compatibility with versions < 1.0.2 */
00186 
00187                         /* basic functions */
00188 
00189 ZEXTERN const char * ZEXPORT zlibVersion OF((void));
00190 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
00191    If the first character differs, the library code actually used is
00192    not compatible with the zlib.h header file used by the application.
00193    This check is automatically made by deflateInit and inflateInit.
00194  */
00195 
00196 /*
00197 ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level));
00198 
00199      Initializes the internal stream state for compression. The fields
00200    zalloc, zfree and opaque must be initialized before by the caller.
00201    If zalloc and zfree are set to Z_NULL, deflateInit updates them to
00202    use default allocation functions.
00203 
00204      The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
00205    1 gives best speed, 9 gives best compression, 0 gives no compression at
00206    all (the input data is simply copied a block at a time).
00207    Z_DEFAULT_COMPRESSION requests a default compromise between speed and
00208    compression (currently equivalent to level 6).
00209 
00210      deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
00211    enough memory, Z_STREAM_ERROR if level is not a valid compression level,
00212    Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
00213    with the version assumed by the caller (ZLIB_VERSION).
00214    msg is set to null if there is no error message.  deflateInit does not
00215    perform any compression: this will be done by deflate().
00216 */
00217 
00218 
00219 ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
00220 /*
00221     deflate compresses as much data as possible, and stops when the input
00222   buffer becomes empty or the output buffer becomes full. It may introduce some
00223   output latency (reading input without producing any output) except when
00224   forced to flush.
00225 
00226     The detailed semantics are as follows. deflate performs one or both of the
00227   following actions:
00228 
00229   - Compress more input starting at next_in and update next_in and avail_in
00230     accordingly. If not all input can be processed (because there is not
00231     enough room in the output buffer), next_in and avail_in are updated and
00232     processing will resume at this point for the next call of deflate().
00233 
00234   - Provide more output starting at next_out and update next_out and avail_out
00235     accordingly. This action is forced if the parameter flush is non zero.
00236     Forcing flush frequently degrades the compression ratio, so this parameter
00237     should be set only when necessary (in interactive applications).
00238     Some output may be provided even if flush is not set.
00239 
00240   Before the call of deflate(), the application should ensure that at least
00241   one of the actions is possible, by providing more input and/or consuming
00242   more output, and updating avail_in or avail_out accordingly; avail_out
00243   should never be zero before the call. The application can consume the
00244   compressed output when it wants, for example when the output buffer is full
00245   (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
00246   and with zero avail_out, it must be called again after making room in the
00247   output buffer because there might be more output pending.
00248 
00249     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
00250   flushed to the output buffer and the output is aligned on a byte boundary, so
00251   that the decompressor can get all input data available so far. (In particular
00252   avail_in is zero after the call if enough output space has been provided
00253   before the call.)  Flushing may degrade compression for some compression
00254   algorithms and so it should be used only when necessary.
00255 
00256     If flush is set to Z_FULL_FLUSH, all output is flushed as with
00257   Z_SYNC_FLUSH, and the compression state is reset so that decompression can
00258   restart from this point if previous compressed data has been damaged or if
00259   random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
00260   the compression.
00261 
00262     If deflate returns with avail_out == 0, this function must be called again
00263   with the same value of the flush parameter and more output space (updated
00264   avail_out), until the flush is complete (deflate returns with non-zero
00265   avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
00266   avail_out is greater than six to avoid repeated flush markers due to
00267   avail_out == 0 on return.
00268 
00269     If the parameter flush is set to Z_FINISH, pending input is processed,
00270   pending output is flushed and deflate returns with Z_STREAM_END if there
00271   was enough output space; if deflate returns with Z_OK, this function must be
00272   called again with Z_FINISH and more output space (updated avail_out) but no
00273   more input data, until it returns with Z_STREAM_END or an error. After
00274   deflate has returned Z_STREAM_END, the only possible operations on the
00275   stream are deflateReset or deflateEnd.
00276 
00277     Z_FINISH can be used immediately after deflateInit if all the compression
00278   is to be done in a single step. In this case, avail_out must be at least
00279   the value returned by deflateBound (see below). If deflate does not return
00280   Z_STREAM_END, then it must be called again as described above.
00281 
00282     deflate() sets strm->adler to the adler32 checksum of all input read
00283   so far (that is, total_in bytes).
00284 
00285     deflate() may update data_type if it can make a good guess about
00286   the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
00287   binary. This field is only for information purposes and does not affect
00288   the compression algorithm in any manner.
00289 
00290     deflate() returns Z_OK if some progress has been made (more input
00291   processed or more output produced), Z_STREAM_END if all input has been
00292   consumed and all output has been produced (only when flush is set to
00293   Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
00294   if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
00295   (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
00296   fatal, and deflate() can be called again with more input and more output
00297   space to continue compressing.
00298 */
00299 
00300 
00301 ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm));
00302 /*
00303      All dynamically allocated data structures for this stream are freed.
00304    This function discards any unprocessed input and does not flush any
00305    pending output.
00306 
00307      deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
00308    stream state was inconsistent, Z_DATA_ERROR if the stream was freed
00309    prematurely (some input or output was discarded). In the error case,
00310    msg may be set but then points to a static string (which must not be
00311    deallocated).
00312 */
00313 
00314 
00315 /*
00316 ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
00317 
00318      Initializes the internal stream state for decompression. The fields
00319    next_in, avail_in, zalloc, zfree and opaque must be initialized before by
00320    the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
00321    value depends on the compression method), inflateInit determines the
00322    compression method from the zlib header and allocates all data structures
00323    accordingly; otherwise the allocation will be deferred to the first call of
00324    inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
00325    use default allocation functions.
00326 
00327      inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
00328    memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
00329    version assumed by the caller.  msg is set to null if there is no error
00330    message. inflateInit does not perform any decompression apart from reading
00331    the zlib header if present: this will be done by inflate().  (So next_in and
00332    avail_in may be modified, but next_out and avail_out are unchanged.)
00333 */
00334 
00335 
00336 ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
00337 /*
00338     inflate decompresses as much data as possible, and stops when the input
00339   buffer becomes empty or the output buffer becomes full. It may introduce
00340   some output latency (reading input without producing any output) except when
00341   forced to flush.
00342 
00343   The detailed semantics are as follows. inflate performs one or both of the
00344   following actions:
00345 
00346   - Decompress more input starting at next_in and update next_in and avail_in
00347     accordingly. If not all input can be processed (because there is not
00348     enough room in the output buffer), next_in is updated and processing
00349     will resume at this point for the next call of inflate().
00350 
00351   - Provide more output starting at next_out and update next_out and avail_out
00352     accordingly.  inflate() provides as much output as possible, until there
00353     is no more input data or no more space in the output buffer (see below
00354     about the flush parameter).
00355 
00356   Before the call of inflate(), the application should ensure that at least
00357   one of the actions is possible, by providing more input and/or consuming
00358   more output, and updating the next_* and avail_* values accordingly.
00359   The application can consume the uncompressed output when it wants, for
00360   example when the output buffer is full (avail_out == 0), or after each
00361   call of inflate(). If inflate returns Z_OK and with zero avail_out, it
00362   must be called again after making room in the output buffer because there
00363   might be more output pending.
00364 
00365     The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH,
00366   Z_FINISH, or Z_BLOCK. Z_SYNC_FLUSH requests that inflate() flush as much
00367   output as possible to the output buffer. Z_BLOCK requests that inflate() stop
00368   if and when it get to the next deflate block boundary. When decoding the zlib
00369   or gzip format, this will cause inflate() to return immediately after the
00370   header and before the first block. When doing a raw inflate, inflate() will
00371   go ahead and process the first block, and will return when it gets to the end
00372   of that block, or when it runs out of data.
00373 
00374     The Z_BLOCK option assists in appending to or combining deflate streams.
00375   Also to assist in this, on return inflate() will set strm->data_type to the
00376   number of unused bits in the last byte taken from strm->next_in, plus 64
00377   if inflate() is currently decoding the last block in the deflate stream,
00378   plus 128 if inflate() returned immediately after decoding an end-of-block
00379   code or decoding the complete header up to just before the first byte of the
00380   deflate stream. The end-of-block will not be indicated until all of the
00381   uncompressed data from that block has been written to strm->next_out.  The
00382   number of unused bits may in general be greater than seven, except when
00383   bit 7 of data_type is set, in which case the number of unused bits will be
00384   less than eight.
00385 
00386     inflate() should normally be called until it returns Z_STREAM_END or an
00387   error. However if all decompression is to be performed in a single step
00388   (a single call of inflate), the parameter flush should be set to
00389   Z_FINISH. In this case all pending input is processed and all pending
00390   output is flushed; avail_out must be large enough to hold all the
00391   uncompressed data. (The size of the uncompressed data may have been saved
00392   by the compressor for this purpose.) The next operation on this stream must
00393   be inflateEnd to deallocate the decompression state. The use of Z_FINISH
00394   is never required, but can be used to inform inflate that a faster approach
00395   may be used for the single inflate() call.
00396 
00397      In this implementation, inflate() always flushes as much output as
00398   possible to the output buffer, and always uses the faster approach on the
00399   first call. So the only effect of the flush parameter in this implementation
00400   is on the return value of inflate(), as noted below, or when it returns early
00401   because Z_BLOCK is used.
00402 
00403      If a preset dictionary is needed after this call (see inflateSetDictionary
00404   below), inflate sets strm-adler to the adler32 checksum of the dictionary
00405   chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
00406   strm->adler to the adler32 checksum of all output produced so far (that is,
00407   total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
00408   below. At the end of the stream, inflate() checks that its computed adler32
00409   checksum is equal to that saved by the compressor and returns Z_STREAM_END
00410   only if the checksum is correct.
00411 
00412     inflate() will decompress and check either zlib-wrapped or gzip-wrapped
00413   deflate data.  The header type is detected automatically.  Any information
00414   contained in the gzip header is not retained, so applications that need that
00415   information should instead use raw inflate, see inflateInit2() below, or
00416   inflateBack() and perform their own processing of the gzip header and
00417   trailer.
00418 
00419     inflate() returns Z_OK if some progress has been made (more input processed
00420   or more output produced), Z_STREAM_END if the end of the compressed data has
00421   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
00422   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
00423   corrupted (input stream not conforming to the zlib format or incorrect check
00424   value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
00425   if next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
00426   Z_BUF_ERROR if no progress is possible or if there was not enough room in the
00427   output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
00428   inflate() can be called again with more input and more output space to
00429   continue decompressing. If Z_DATA_ERROR is returned, the application may then
00430   call inflateSync() to look for a good compression block if a partial recovery
00431   of the data is desired.
00432 */
00433 
00434 
00435 ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm));
00436 /*
00437      All dynamically allocated data structures for this stream are freed.
00438    This function discards any unprocessed input and does not flush any
00439    pending output.
00440 
00441      inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
00442    was inconsistent. In the error case, msg may be set but then points to a
00443    static string (which must not be deallocated).
00444 */
00445 
00446                         /* Advanced functions */
00447 
00448 /*
00449     The following functions are needed only in some special applications.
00450 */
00451 
00452 /*
00453 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,
00454                                      int  level,
00455                                      int  method,
00456                                      int  windowBits,
00457                                      int  memLevel,
00458                                      int  strategy));
00459 
00460      This is another version of deflateInit with more compression options. The
00461    fields next_in, zalloc, zfree and opaque must be initialized before by
00462    the caller.
00463 
00464      The method parameter is the compression method. It must be Z_DEFLATED in
00465    this version of the library.
00466 
00467      The windowBits parameter is the base two logarithm of the window size
00468    (the size of the history buffer). It should be in the range 8..15 for this
00469    version of the library. Larger values of this parameter result in better
00470    compression at the expense of memory usage. The default value is 15 if
00471    deflateInit is used instead.
00472 
00473      windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
00474    determines the window size. deflate() will then generate raw deflate data
00475    with no zlib header or trailer, and will not compute an adler32 check value.
00476 
00477      windowBits can also be greater than 15 for optional gzip encoding. Add
00478    16 to windowBits to write a simple gzip header and trailer around the
00479    compressed data instead of a zlib wrapper. The gzip header will have no
00480    file name, no extra data, no comment, no modification time (set to zero),
00481    no header crc, and the operating system will be set to 255 (unknown).
00482 
00483      The memLevel parameter specifies how much memory should be allocated
00484    for the internal compression state. memLevel=1 uses minimum memory but
00485    is slow and reduces compression ratio; memLevel=9 uses maximum memory
00486    for optimal speed. The default value is 8. See zconf.h for total memory
00487    usage as a function of windowBits and memLevel.
00488 
00489      The strategy parameter is used to tune the compression algorithm. Use the
00490    value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
00491    filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
00492    string match), or Z_RLE to limit match distances to one (run-length
00493    encoding). Filtered data consists mostly of small values with a somewhat
00494    random distribution. In this case, the compression algorithm is tuned to
00495    compress them better. The effect of Z_FILTERED is to force more Huffman
00496    coding and less string matching; it is somewhat intermediate between
00497    Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as
00498    Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy
00499    parameter only affects the compression ratio but not the correctness of the
00500    compressed output even if it is not set appropriately.
00501 
00502       deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
00503    memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
00504    method). msg is set to null if there is no error message.  deflateInit2 does
00505    not perform any compression: this will be done by deflate().
00506 */
00507 
00508 ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
00509                                              const Bytef *dictionary,
00510                                              uInt  dictLength));
00511 /*
00512      Initializes the compression dictionary from the given byte sequence
00513    without producing any compressed output. This function must be called
00514    immediately after deflateInit, deflateInit2 or deflateReset, before any
00515    call of deflate. The compressor and decompressor must use exactly the same
00516    dictionary (see inflateSetDictionary).
00517 
00518      The dictionary should consist of strings (byte sequences) that are likely
00519    to be encountered later in the data to be compressed, with the most commonly
00520    used strings preferably put towards the end of the dictionary. Using a
00521    dictionary is most useful when the data to be compressed is short and can be
00522    predicted with good accuracy; the data can then be compressed better than
00523    with the default empty dictionary.
00524 
00525      Depending on the size of the compression data structures selected by
00526    deflateInit or deflateInit2, a part of the dictionary may in effect be
00527    discarded, for example if the dictionary is larger than the window size in
00528    deflate or deflate2. Thus the strings most likely to be useful should be
00529    put at the end of the dictionary, not at the front.
00530 
00531      Upon return of this function, strm->adler is set to the adler32 value
00532    of the dictionary; the decompressor may later use this value to determine
00533    which dictionary has been used by the compressor. (The adler32 value
00534    applies to the whole dictionary even if only a subset of the dictionary is
00535    actually used by the compressor.) If a raw deflate was requested, then the
00536    adler32 value is not computed and strm->adler is not set.
00537 
00538      deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
00539    parameter is invalid (such as NULL dictionary) or the stream state is
00540    inconsistent (for example if deflate has already been called for this stream
00541    or if the compression method is bsort). deflateSetDictionary does not
00542    perform any compression: this will be done by deflate().
00543 */
00544 
00545 ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
00546                                     z_streamp source));
00547 /*
00548      Sets the destination stream as a complete copy of the source stream.
00549 
00550      This function can be useful when several compression strategies will be
00551    tried, for example when there are several ways of pre-processing the input
00552    data with a filter. The streams that will be discarded should then be freed
00553    by calling deflateEnd.  Note that deflateCopy duplicates the internal
00554    compression state which can be quite large, so this strategy is slow and
00555    can consume lots of memory.
00556 
00557      deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
00558    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
00559    (such as zalloc being NULL). msg is left unchanged in both source and
00560    destination.
00561 */
00562 
00563 ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm));
00564 /*
00565      This function is equivalent to deflateEnd followed by deflateInit,
00566    but does not free and reallocate all the internal compression state.
00567    The stream will keep the same compression level and any other attributes
00568    that may have been set by deflateInit2.
00569 
00570       deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
00571    stream state was inconsistent (such as zalloc or state being NULL).
00572 */
00573 
00574 ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
00575                                       int level,
00576                                       int strategy));
00577 /*
00578      Dynamically update the compression level and compression strategy.  The
00579    interpretation of level and strategy is as in deflateInit2.  This can be
00580    used to switch between compression and straight copy of the input data, or
00581    to switch to a different kind of input data requiring a different
00582    strategy. If the compression level is changed, the input available so far
00583    is compressed with the old level (and may be flushed); the new level will
00584    take effect only at the next call of deflate().
00585 
00586      Before the call of deflateParams, the stream state must be set as for
00587    a call of deflate(), since the currently available input may have to
00588    be compressed and flushed. In particular, strm->avail_out must be non-zero.
00589 
00590      deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
00591    stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
00592    if strm->avail_out was zero.
00593 */
00594 
00595 ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
00596                                        uLong sourceLen));
00597 /*
00598      deflateBound() returns an upper bound on the compressed size after
00599    deflation of sourceLen bytes.  It must be called after deflateInit()
00600    or deflateInit2().  This would be used to allocate an output buffer
00601    for deflation in a single pass, and so would be called before deflate().
00602 */
00603 
00604 ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
00605                                      int bits,
00606                                      int value));
00607 /*
00608      deflatePrime() inserts bits in the deflate output stream.  The intent
00609   is that this function is used to start off the deflate output with the
00610   bits leftover from a previous deflate stream when appending to it.  As such,
00611   this function can only be used for raw deflate, and must be used before the
00612   first deflate() call after a deflateInit2() or deflateReset().  bits must be
00613   less than or equal to 16, and that many of the least significant bits of
00614   value will be inserted in the output.
00615 
00616       deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
00617    stream state was inconsistent.
00618 */
00619 
00620 /*
00621 ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm,
00622                                      int  windowBits));
00623 
00624      This is another version of inflateInit with an extra parameter. The
00625    fields next_in, avail_in, zalloc, zfree and opaque must be initialized
00626    before by the caller.
00627 
00628      The windowBits parameter is the base two logarithm of the maximum window
00629    size (the size of the history buffer).  It should be in the range 8..15 for
00630    this version of the library. The default value is 15 if inflateInit is used
00631    instead. windowBits must be greater than or equal to the windowBits value
00632    provided to deflateInit2() while compressing, or it must be equal to 15 if
00633    deflateInit2() was not used. If a compressed stream with a larger window
00634    size is given as input, inflate() will return with the error code
00635    Z_DATA_ERROR instead of trying to allocate a larger window.
00636 
00637      windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
00638    determines the window size. inflate() will then process raw deflate data,
00639    not looking for a zlib or gzip header, not generating a check value, and not
00640    looking for any check values for comparison at the end of the stream. This
00641    is for use with other formats that use the deflate compressed data format
00642    such as zip.  Those formats provide their own check values. If a custom
00643    format is developed using the raw deflate format for compressed data, it is
00644    recommended that a check value such as an adler32 or a crc32 be applied to
00645    the uncompressed data as is done in the zlib, gzip, and zip formats.  For
00646    most applications, the zlib format should be used as is. Note that comments
00647    above on the use in deflateInit2() applies to the magnitude of windowBits.
00648 
00649      windowBits can also be greater than 15 for optional gzip decoding. Add
00650    32 to windowBits to enable zlib and gzip decoding with automatic header
00651    detection, or add 16 to decode only the gzip format (the zlib format will
00652    return a Z_DATA_ERROR).
00653 
00654      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
00655    memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
00656    memLevel). msg is set to null if there is no error message.  inflateInit2
00657    does not perform any decompression apart from reading the zlib header if
00658    present: this will be done by inflate(). (So next_in and avail_in may be
00659    modified, but next_out and avail_out are unchanged.)
00660 */
00661 
00662 ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
00663                                              const Bytef *dictionary,
00664                                              uInt  dictLength));
00665 /*
00666      Initializes the decompression dictionary from the given uncompressed byte
00667    sequence. This function must be called immediately after a call of inflate
00668    if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
00669    can be determined from the adler32 value returned by this call of
00670    inflate. The compressor and decompressor must use exactly the same
00671    dictionary (see deflateSetDictionary).
00672 
00673      inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
00674    parameter is invalid (such as NULL dictionary) or the stream state is
00675    inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
00676    expected one (incorrect adler32 value). inflateSetDictionary does not
00677    perform any decompression: this will be done by subsequent calls of
00678    inflate().
00679 */
00680 
00681 ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
00682 /*
00683     Skips invalid compressed data until a full flush point (see above the
00684   description of deflate with Z_FULL_FLUSH) can be found, or until all
00685   available input is skipped. No output is provided.
00686 
00687     inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
00688   if no more input was provided, Z_DATA_ERROR if no flush point has been found,
00689   or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
00690   case, the application may save the current current value of total_in which
00691   indicates where valid compressed data was found. In the error case, the
00692   application may repeatedly call inflateSync, providing more input each time,
00693   until success or end of the input data.
00694 */
00695 
00696 ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
00697                                     z_streamp source));
00698 /*
00699      Sets the destination stream as a complete copy of the source stream.
00700 
00701      This function can be useful when randomly accessing a large stream.  The
00702    first pass through the stream can periodically record the inflate state,
00703    allowing restarting inflate at those points when randomly accessing the
00704    stream.
00705 
00706      inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
00707    enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
00708    (such as zalloc being NULL). msg is left unchanged in both source and
00709    destination.
00710 */
00711 
00712 ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm));
00713 /*
00714      This function is equivalent to inflateEnd followed by inflateInit,
00715    but does not free and reallocate all the internal decompression state.
00716    The stream will keep attributes that may have been set by inflateInit2.
00717 
00718       inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
00719    stream state was inconsistent (such as zalloc or state being NULL).
00720 */
00721 
00722 /*
00723 ZEXTERN int ZEXPORT inflateBackInit OF((z_stream FAR *strm, int windowBits,
00724                                         unsigned char FAR *window));
00725 
00726      Initialize the internal stream state for decompression using inflateBack()
00727    calls.  The fields zalloc, zfree and opaque in strm must be initialized
00728    before the call.  If zalloc and zfree are Z_NULL, then the default library-
00729    derived memory allocation routines are used.  windowBits is the base two
00730    logarithm of the window size, in the range 8..15.  window is a caller
00731    supplied buffer of that size.  Except for special applications where it is
00732    assured that deflate was used with small window sizes, windowBits must be 15
00733    and a 32K byte window must be supplied to be able to decompress general
00734    deflate streams.
00735 
00736      See inflateBack() for the usage of these routines.
00737 
00738      inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
00739    the paramaters are invalid, Z_MEM_ERROR if the internal state could not
00740    be allocated, or Z_VERSION_ERROR if the version of the library does not
00741    match the version of the header file.
00742 */
00743 
00744 typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
00745 typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
00746 
00747 ZEXTERN int ZEXPORT inflateBack OF((z_stream FAR *strm,
00748                                     in_func in, void FAR *in_desc,
00749                                     out_func out, void FAR *out_desc));
00750 /*
00751      inflateBack() does a raw inflate with a single call using a call-back
00752    interface for input and output.  This is more efficient than inflate() for
00753    file i/o applications in that it avoids copying between the output and the
00754    sliding window by simply making the window itself the output buffer.  This
00755    function trusts the application to not change the output buffer passed by
00756    the output function, at least until inflateBack() returns.
00757 
00758      inflateBackInit() must be called first to allocate the internal state
00759    and to initialize the state with the user-provided window buffer.
00760    inflateBack() may then be used multiple times to inflate a complete, raw
00761    deflate stream with each call.  inflateBackEnd() is then called to free
00762    the allocated state.
00763 
00764      A raw deflate stream is one with no zlib or gzip header or trailer.
00765    This routine would normally be used in a utility that reads zip or gzip
00766    files and writes out uncompressed files.  The utility would decode the
00767    header and process the trailer on its own, hence this routine expects
00768    only the raw deflate stream to decompress.  This is different from the
00769    normal behavior of inflate(), which expects either a zlib or gzip header and
00770    trailer around the deflate stream.
00771 
00772      inflateBack() uses two subroutines supplied by the caller that are then
00773    called by inflateBack() for input and output.  inflateBack() calls those
00774    routines until it reads a complete deflate stream and writes out all of the
00775    uncompressed data, or until it encounters an error.  The function's
00776    parameters and return types are defined above in the in_func and out_func
00777    typedefs.  inflateBack() will call in(in_desc, &buf) which should return the
00778    number of bytes of provided input, and a pointer to that input in buf.  If
00779    there is no input available, in() must return zero--buf is ignored in that
00780    case--and inflateBack() will return a buffer error.  inflateBack() will call
00781    out(out_desc, buf, len) to write the uncompressed data buf[0..len-1].  out()
00782    should return zero on success, or non-zero on failure.  If out() returns
00783    non-zero, inflateBack() will return with an error.  Neither in() nor out()
00784    are permitted to change the contents of the window provided to
00785    inflateBackInit(), which is also the buffer that out() uses to write from.
00786    The length written by out() will be at most the window size.  Any non-zero
00787    amount of input may be provided by in().
00788 
00789      For convenience, inflateBack() can be provided input on the first call by
00790    setting strm->next_in and strm->avail_in.  If that input is exhausted, then
00791    in() will be called.  Therefore strm->next_in must be initialized before
00792    calling inflateBack().  If strm->next_in is Z_NULL, then in() will be called
00793    immediately for input.  If strm->next_in is not Z_NULL, then strm->avail_in
00794    must also be initialized, and then if strm->avail_in is not zero, input will
00795    initially be taken from strm->next_in[0 .. strm->avail_in - 1].
00796 
00797      The in_desc and out_desc parameters of inflateBack() is passed as the
00798    first parameter of in() and out() respectively when they are called.  These
00799    descriptors can be optionally used to pass any information that the caller-
00800    supplied in() and out() functions need to do their job.
00801 
00802      On return, inflateBack() will set strm->next_in and strm->avail_in to
00803    pass back any unused input that was provided by the last in() call.  The
00804    return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
00805    if in() or out() returned an error, Z_DATA_ERROR if there was a format
00806    error in the deflate stream (in which case strm->msg is set to indicate the
00807    nature of the error), or Z_STREAM_ERROR if the stream was not properly
00808    initialized.  In the case of Z_BUF_ERROR, an input or output error can be
00809    distinguished using strm->next_in which will be Z_NULL only if in() returned
00810    an error.  If strm->next is not Z_NULL, then the Z_BUF_ERROR was due to
00811    out() returning non-zero.  (in() will always be called before out(), so
00812    strm->next_in is assured to be defined if out() returns non-zero.)  Note
00813    that inflateBack() cannot return Z_OK.
00814 */
00815 
00816 ZEXTERN int ZEXPORT inflateBackEnd OF((z_stream FAR *strm));
00817 /*
00818      All memory allocated by inflateBackInit() is freed.
00819 
00820      inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
00821    state was inconsistent.
00822 */
00823 
00824 ZEXTERN uLong ZEXPORT zlibCompileFlags OF((void));
00825 /* Return flags indicating compile-time options.
00826 
00827     Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
00828      1.0: size of uInt
00829      3.2: size of uLong
00830      5.4: size of voidpf (pointer)
00831      7.6: size of z_off_t
00832 
00833     Compiler, assembler, and debug options:
00834      8: DEBUG
00835      9: ASMV or ASMINF -- use ASM code
00836      10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
00837      11: 0 (reserved)
00838 
00839     One-time table building (smaller code, but not thread-safe if true):
00840      12: BUILDFIXED -- build static block decoding tables when needed
00841      13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
00842      14,15: 0 (reserved)
00843 
00844     Library content (indicates missing functionality):
00845      16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
00846                           deflate code when not needed)
00847      17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
00848                     and decode gzip streams (to avoid linking crc code)
00849      18-19: 0 (reserved)
00850 
00851     Operation variations (changes in library functionality):
00852      20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
00853      21: FASTEST -- deflate algorithm with only one, lowest compression level
00854      22,23: 0 (reserved)
00855 
00856     The sprintf variant used by gzprintf (zero is best):
00857      24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
00858      25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
00859      26: 0 = returns value, 1 = void -- 1 means inferred string length returned
00860 
00861     Remainder:
00862      27-31: 0 (reserved)
00863  */
00864 
00865 
00866                         /* utility functions */
00867 
00868 /*
00869      The following utility functions are implemented on top of the
00870    basic stream-oriented functions. To simplify the interface, some
00871    default options are assumed (compression level and memory usage,
00872    standard memory allocation functions). The source code of these
00873    utility functions can easily be modified if you need special options.
00874 */
00875 
00876 ZEXTERN int ZEXPORT compress OF((Bytef *dest,   uLongf *destLen,
00877                                  const Bytef *source, uLong sourceLen));
00878 /*
00879      Compresses the source buffer into the destination buffer.  sourceLen is
00880    the byte length of the source buffer. Upon entry, destLen is the total
00881    size of the destination buffer, which must be at least the value returned
00882    by compressBound(sourceLen). Upon exit, destLen is the actual size of the
00883    compressed buffer.
00884      This function can be used to compress a whole file at once if the
00885    input file is mmap'ed.
00886      compress returns Z_OK if success, Z_MEM_ERROR if there was not
00887    enough memory, Z_BUF_ERROR if there was not enough room in the output
00888    buffer.
00889 */
00890 
00891 ZEXTERN int ZEXPORT compress2 OF((Bytef *dest,   uLongf *destLen,
00892                                   const Bytef *source, uLong sourceLen,
00893                                   int level));
00894 /*
00895      Compresses the source buffer into the destination buffer. The level
00896    parameter has the same meaning as in deflateInit.  sourceLen is the byte
00897    length of the source buffer. Upon entry, destLen is the total size of the
00898    destination buffer, which must be at least the value returned by
00899    compressBound(sourceLen). Upon exit, destLen is the actual size of the
00900    compressed buffer.
00901 
00902      compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
00903    memory, Z_BUF_ERROR if there was not enough room in the output buffer,
00904    Z_STREAM_ERROR if the level parameter is invalid.
00905 */
00906 
00907 ZEXTERN uLong ZEXPORT compressBound OF((uLong sourceLen));
00908 /*
00909      compressBound() returns an upper bound on the compressed size after
00910    compress() or compress2() on sourceLen bytes.  It would be used before
00911    a compress() or compress2() call to allocate the destination buffer.
00912 */
00913 
00914 ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
00915                                    const Bytef *source, uLong sourceLen));
00916 /*
00917      Decompresses the source buffer into the destination buffer.  sourceLen is
00918    the byte length of the source buffer. Upon entry, destLen is the total
00919    size of the destination buffer, which must be large enough to hold the
00920    entire uncompressed data. (The size of the uncompressed data must have
00921    been saved previously by the compressor and transmitted to the decompressor
00922    by some mechanism outside the scope of this compression library.)
00923    Upon exit, destLen is the actual size of the compressed buffer.
00924      This function can be used to decompress a whole file at once if the
00925    input file is mmap'ed.
00926 
00927      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
00928    enough memory, Z_BUF_ERROR if there was not enough room in the output
00929    buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.
00930 */
00931 
00932 
00933 typedef voidp gzFile;
00934 
00935 ZEXTERN gzFile ZEXPORT gzopen  OF((const char *path, const char *mode));
00936 /*
00937      Opens a gzip (.gz) file for reading or writing. The mode parameter
00938    is as in fopen ("rb" or "wb") but can also include a compression level
00939    ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
00940    Huffman only compression as in "wb1h", or 'R' for run-length encoding
00941    as in "wb1R". (See the description of deflateInit2 for more information
00942    about the strategy parameter.)
00943 
00944      gzopen can be used to read a file which is not in gzip format; in this
00945    case gzread will directly read from the file without decompression.
00946 
00947      gzopen returns NULL if the file could not be opened or if there was
00948    insufficient memory to allocate the (de)compression state; errno
00949    can be checked to distinguish the two cases (if errno is zero, the
00950    zlib error is Z_MEM_ERROR).  */
00951 
00952 ZEXTERN gzFile ZEXPORT gzdopen  OF((int fd, const char *mode));
00953 /*
00954      gzdopen() associates a gzFile with the file descriptor fd.  File
00955    descriptors are obtained from calls like open, dup, creat, pipe or
00956    fileno (in the file has been previously opened with fopen).
00957    The mode parameter is as in gzopen.
00958      The next call of gzclose on the returned gzFile will also close the
00959    file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
00960    descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
00961      gzdopen returns NULL if there was insufficient memory to allocate
00962    the (de)compression state.
00963 */
00964 
00965 ZEXTERN int ZEXPORT gzsetparams OF((gzFile file, int level, int strategy));
00966 /*
00967      Dynamically update the compression level or strategy. See the description
00968    of deflateInit2 for the meaning of these parameters.
00969      gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
00970    opened for writing.
00971 */
00972 
00973 ZEXTERN int ZEXPORT    gzread  OF((gzFile file, voidp buf, unsigned len));
00974 /*
00975      Reads the given number of uncompressed bytes from the compressed file.
00976    If the input file was not in gzip format, gzread copies the given number
00977    of bytes into the buffer.
00978      gzread returns the number of uncompressed bytes actually read (0 for
00979    end of file, -1 for error). */
00980 
00981 ZEXTERN int ZEXPORT    gzwrite OF((gzFile file,
00982                                    voidpc buf, unsigned len));
00983 /*
00984      Writes the given number of uncompressed bytes into the compressed file.
00985    gzwrite returns the number of uncompressed bytes actually written
00986    (0 in case of error).
00987 */
00988 
00989 ZEXTERN int ZEXPORTVA   gzprintf OF((gzFile file, const char *format, ...));
00990 /*
00991      Converts, formats, and writes the args to the compressed file under
00992    control of the format string, as in fprintf. gzprintf returns the number of
00993    uncompressed bytes actually written (0 in case of error).  The number of
00994    uncompressed bytes written is limited to 4095. The caller should assure that
00995    this limit is not exceeded. If it is exceeded, then gzprintf() will return
00996    return an error (0) with nothing written. In this case, there may also be a
00997    buffer overflow with unpredictable consequences, which is possible only if
00998    zlib was compiled with the insecure functions sprintf() or vsprintf()
00999    because the secure snprintf() or vsnprintf() functions were not available.
01000 */
01001 
01002 ZEXTERN int ZEXPORT gzputs OF((gzFile file, const char *s));
01003 /*
01004       Writes the given null-terminated string to the compressed file, excluding
01005    the terminating null character.
01006       gzputs returns the number of characters written, or -1 in case of error.
01007 */
01008 
01009 ZEXTERN char * ZEXPORT gzgets OF((gzFile file, char *buf, int len));
01010 /*
01011       Reads bytes from the compressed file until len-1 characters are read, or
01012    a newline character is read and transferred to buf, or an end-of-file
01013    condition is encountered.  The string is then terminated with a null
01014    character.
01015       gzgets returns buf, or Z_NULL in case of error.
01016 */
01017 
01018 ZEXTERN int ZEXPORT    gzputc OF((gzFile file, int c));
01019 /*
01020       Writes c, converted to an unsigned char, into the compressed file.
01021    gzputc returns the value that was written, or -1 in case of error.
01022 */
01023 
01024 ZEXTERN int ZEXPORT    gzgetc OF((gzFile file));
01025 /*
01026       Reads one byte from the compressed file. gzgetc returns this byte
01027    or -1 in case of end of file or error.
01028 */
01029 
01030 ZEXTERN int ZEXPORT    gzungetc OF((int c, gzFile file));
01031 /*
01032       Push one character back onto the stream to be read again later.
01033    Only one character of push-back is allowed.  gzungetc() returns the
01034    character pushed, or -1 on failure.  gzungetc() will fail if a
01035    character has been pushed but not read yet, or if c is -1. The pushed
01036    character will be discarded if the stream is repositioned with gzseek()
01037    or gzrewind().
01038 */
01039 
01040 ZEXTERN int ZEXPORT    gzflush OF((gzFile file, int flush));
01041 /*
01042      Flushes all pending output into the compressed file. The parameter
01043    flush is as in the deflate() function. The return value is the zlib
01044    error number (see function gzerror below). gzflush returns Z_OK if
01045    the flush parameter is Z_FINISH and all output could be flushed.
01046      gzflush should be called only when strictly necessary because it can
01047    degrade compression.
01048 */
01049 
01050 ZEXTERN z_off_t ZEXPORT    gzseek OF((gzFile file,
01051                                       z_off_t offset, int whence));
01052 /*
01053       Sets the starting position for the next gzread or gzwrite on the
01054    given compressed file. The offset represents a number of bytes in the
01055    uncompressed data stream. The whence parameter is defined as in lseek(2);
01056    the value SEEK_END is not supported.
01057      If the file is opened for reading, this function is emulated but can be
01058    extremely slow. If the file is opened for writing, only forward seeks are
01059    supported; gzseek then compresses a sequence of zeroes up to the new
01060    starting position.
01061 
01062       gzseek returns the resulting offset location as measured in bytes from
01063    the beginning of the uncompressed stream, or -1 in case of error, in
01064    particular if the file is opened for writing and the new starting position
01065    would be before the current position.
01066 */
01067 
01068 ZEXTERN int ZEXPORT    gzrewind OF((gzFile file));
01069 /*
01070      Rewinds the given file. This function is supported only for reading.
01071 
01072    gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
01073 */
01074 
01075 ZEXTERN z_off_t ZEXPORT    gztell OF((gzFile file));
01076 /*
01077      Returns the starting position for the next gzread or gzwrite on the
01078    given compressed file. This position represents a number of bytes in the
01079    uncompressed data stream.
01080 
01081    gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
01082 */
01083 
01084 ZEXTERN int ZEXPORT gzeof OF((gzFile file));
01085 /*
01086      Returns 1 when EOF has previously been detected reading the given
01087    input stream, otherwise zero.
01088 */
01089 
01090 ZEXTERN int ZEXPORT    gzclose OF((gzFile file));
01091 /*
01092      Flushes all pending output if necessary, closes the compressed file
01093    and deallocates all the (de)compression state. The return value is the zlib
01094    error number (see function gzerror below).
01095 */
01096 
01097 ZEXTERN const char * ZEXPORT gzerror OF((gzFile file, int *errnum));
01098 /*
01099      Returns the error message for the last error which occurred on the
01100    given compressed file. errnum is set to zlib error number. If an
01101    error occurred in the file system and not in the compression library,
01102    errnum is set to Z_ERRNO and the application may consult errno
01103    to get the exact error code.
01104 */
01105 
01106 ZEXTERN void ZEXPORT gzclearerr OF((gzFile file));
01107 /*
01108      Clears the error and end-of-file flags for file. This is analogous to the
01109    clearerr() function in stdio. This is useful for continuing to read a gzip
01110    file that is being written concurrently.
01111 */
01112 
01113                         /* checksum functions */
01114 
01115 /*
01116      These functions are not related to compression but are exported
01117    anyway because they might be useful in applications using the
01118    compression library.
01119 */
01120 
01121 ZEXTERN uLong ZEXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
01122 
01123 /*
01124      Update a running Adler-32 checksum with the bytes buf[0..len-1] and
01125    return the updated checksum. If buf is NULL, this function returns
01126    the required initial value for the checksum.
01127    An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
01128    much faster. Usage example:
01129 
01130      uLong adler = adler32(0L, Z_NULL, 0);
01131 
01132      while (read_buffer(buffer, length) != EOF) {
01133        adler = adler32(adler, buffer, length);
01134      }
01135      if (adler != original_adler) error();
01136 */
01137 
01138 ZEXTERN uLong ZEXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
01139 /*
01140      Update a running crc with the bytes buf[0..len-1] and return the updated
01141    crc. If buf is NULL, this function returns the required initial value
01142    for the crc. Pre- and post-conditioning (one's complement) is performed
01143    within this function so it shouldn't be done by the application.
01144    Usage example:
01145 
01146      uLong crc = crc32(0L, Z_NULL, 0);
01147 
01148      while (read_buffer(buffer, length) != EOF) {
01149        crc = crc32(crc, buffer, length);
01150      }
01151      if (crc != original_crc) error();
01152 */
01153 
01154 
01155                         /* various hacks, don't look :) */
01156 
01157 /* deflateInit and inflateInit are macros to allow checking the zlib version
01158  * and the compiler's view of z_stream:
01159  */
01160 ZEXTERN int ZEXPORT deflateInit_ OF((z_streamp strm, int level,
01161                                      const char *version, int stream_size));
01162 ZEXTERN int ZEXPORT inflateInit_ OF((z_streamp strm,
01163                                      const char *version, int stream_size));
01164 ZEXTERN int ZEXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
01165                                       int windowBits, int memLevel,
01166                                       int strategy, const char *version,
01167                                       int stream_size));
01168 ZEXTERN int ZEXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
01169                                       const char *version, int stream_size));
01170 ZEXTERN int ZEXPORT inflateBackInit_ OF((z_stream FAR *strm, int windowBits,
01171                                          unsigned char FAR *window,
01172                                          const char *version,
01173                                          int stream_size));
01174 #define deflateInit(strm, level) \
01175         deflateInit_((strm), (level),       ZLIB_VERSION, sizeof(z_stream))
01176 #define inflateInit(strm) \
01177         inflateInit_((strm),                ZLIB_VERSION, sizeof(z_stream))
01178 #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
01179         deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
01180                       (strategy),           ZLIB_VERSION, sizeof(z_stream))
01181 #define inflateInit2(strm, windowBits) \
01182         inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
01183 #define inflateBackInit(strm, windowBits, window) \
01184         inflateBackInit_((strm), (windowBits), (window), \
01185         ZLIB_VERSION, sizeof(z_stream))
01186 
01187 
01188 #if !defined(ZUTIL_H) && !defined(NO_DUMMY_DECL)
01189     struct internal_state {int dummy;}; /* hack for buggy compilers */
01190 #endif
01191 
01192 ZEXTERN const char   * ZEXPORT zError           OF((int err));
01193 ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp z));
01194 ZEXTERN const uLongf * ZEXPORT get_crc_table    OF((void));
01195 
01196 #ifdef __cplusplus
01197 }
01198 #endif
01199 
01200 #endif /* ZLIB_H */