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/src/freetype/src/gzip/zlib.h

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  1/* zlib.h -- interface of the 'zlib' general purpose compression library
  2  version 1.1.4, March 11th, 2002
  3
  4  Copyright (C) 1995-2002 Jean-loup Gailly and Mark Adler
  5
  6  This software is provided 'as-is', without any express or implied
  7  warranty.  In no event will the authors be held liable for any damages
  8  arising from the use of this software.
  9
 10  Permission is granted to anyone to use this software for any purpose,
 11  including commercial applications, and to alter it and redistribute it
 12  freely, subject to the following restrictions:
 13
 14  1. The origin of this software must not be misrepresented; you must not
 15     claim that you wrote the original software. If you use this software
 16     in a product, an acknowledgment in the product documentation would be
 17     appreciated but is not required.
 18  2. Altered source versions must be plainly marked as such, and must not be
 19     misrepresented as being the original software.
 20  3. This notice may not be removed or altered from any source distribution.
 21
 22  Jean-loup Gailly        Mark Adler
 23  jloup@gzip.org          madler@alumni.caltech.edu
 24
 25
 26  The data format used by the zlib library is described by RFCs (Request for
 27  Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt
 28  (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
 29*/
 30
 31#ifndef _ZLIB_H
 32#define _ZLIB_H
 33
 34#include "zconf.h"
 35
 36#ifdef __cplusplus
 37extern "C" {
 38#endif
 39
 40#define ZLIB_VERSION "1.1.4"
 41
 42/*
 43     The 'zlib' compression library provides in-memory compression and
 44  decompression functions, including integrity checks of the uncompressed
 45  data.  This version of the library supports only one compression method
 46  (deflation) but other algorithms will be added later and will have the same
 47  stream interface.
 48
 49     Compression can be done in a single step if the buffers are large
 50  enough (for example if an input file is mmap'ed), or can be done by
 51  repeated calls of the compression function.  In the latter case, the
 52  application must provide more input and/or consume the output
 53  (providing more output space) before each call.
 54
 55     The library also supports reading and writing files in gzip (.gz) format
 56  with an interface similar to that of stdio.
 57
 58     The library does not install any signal handler. The decoder checks
 59  the consistency of the compressed data, so the library should never
 60  crash even in case of corrupted input.
 61*/
 62
 63typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
 64typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
 65
 66struct internal_state;
 67
 68typedef struct z_stream_s {
 69    Bytef    *next_in;  /* next input byte */
 70    uInt     avail_in;  /* number of bytes available at next_in */
 71    uLong    total_in;  /* total nb of input bytes read so far */
 72
 73    Bytef    *next_out; /* next output byte should be put there */
 74    uInt     avail_out; /* remaining free space at next_out */
 75    uLong    total_out; /* total nb of bytes output so far */
 76
 77    char     *msg;      /* last error message, NULL if no error */
 78    struct internal_state FAR *state; /* not visible by applications */
 79
 80    alloc_func zalloc;  /* used to allocate the internal state */
 81    free_func  zfree;   /* used to free the internal state */
 82    voidpf     opaque;  /* private data object passed to zalloc and zfree */
 83
 84    int     data_type;  /* best guess about the data type: ascii or binary */
 85    uLong   adler;      /* adler32 value of the uncompressed data */
 86    uLong   reserved;   /* reserved for future use */
 87} z_stream;
 88
 89typedef z_stream FAR *z_streamp;
 90
 91/*
 92   The application must update next_in and avail_in when avail_in has
 93   dropped to zero. It must update next_out and avail_out when avail_out
 94   has dropped to zero. The application must initialize zalloc, zfree and
 95   opaque before calling the init function. All other fields are set by the
 96   compression library and must not be updated by the application.
 97
 98   The opaque value provided by the application will be passed as the first
 99   parameter for calls of zalloc and zfree. This can be useful for custom
100   memory management. The compression library attaches no meaning to the
101   opaque value.
102
103   zalloc must return Z_NULL if there is not enough memory for the object.
104   If zlib is used in a multi-threaded application, zalloc and zfree must be
105   thread safe.
106
107   On 16-bit systems, the functions zalloc and zfree must be able to allocate
108   exactly 65536 bytes, but will not be required to allocate more than this
109   if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
110   pointers returned by zalloc for objects of exactly 65536 bytes *must*
111   have their offset normalized to zero. The default allocation function
112   provided by this library ensures this (see zutil.c). To reduce memory
113   requirements and avoid any allocation of 64K objects, at the expense of
114   compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
115
116   The fields total_in and total_out can be used for statistics or
117   progress reports. After compression, total_in holds the total size of
118   the uncompressed data and may be saved for use in the decompressor
119   (particularly if the decompressor wants to decompress everything in
120   a single step).
121*/
122
123                        /* constants */
124
125#define Z_NO_FLUSH      0
126#define Z_PARTIAL_FLUSH 1 /* will be removed, use Z_SYNC_FLUSH instead */
127#define Z_SYNC_FLUSH    2
128#define Z_FULL_FLUSH    3
129#define Z_FINISH        4
130/* Allowed flush values; see deflate() below for details */
131
132#define Z_OK            0
133#define Z_STREAM_END    1
134#define Z_NEED_DICT     2
135#define Z_ERRNO        (-1)
136#define Z_STREAM_ERROR (-2)
137#define Z_DATA_ERROR   (-3)
138#define Z_MEM_ERROR    (-4)
139#define Z_BUF_ERROR    (-5)
140#define Z_VERSION_ERROR (-6)
141/* Return codes for the compression/decompression functions. Negative
142 * values are errors, positive values are used for special but normal events.
143 */
144
145#define Z_NO_COMPRESSION         0
146#define Z_BEST_SPEED             1
147#define Z_BEST_COMPRESSION       9
148#define Z_DEFAULT_COMPRESSION  (-1)
149/* compression levels */
150
151#define Z_FILTERED            1
152#define Z_HUFFMAN_ONLY        2
153#define Z_DEFAULT_STRATEGY    0
154/* compression strategy; see deflateInit2() below for details */
155
156#define Z_BINARY   0
157#define Z_ASCII    1
158#define Z_UNKNOWN  2
159/* Possible values of the data_type field */
160
161#define Z_DEFLATED   8
162/* The deflate compression method (the only one supported in this version) */
163
164#define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
165
166
167                        /* basic functions */
168
169/* The application can compare zlibVersion and ZLIB_VERSION for consistency.
170   If the first character differs, the library code actually used is
171   not compatible with the zlib.h header file used by the application.
172   This check is automatically made by deflateInit and inflateInit.
173 */
174
175/*
176ZEXTERN(int)  deflateInit OF((z_streamp strm, int level));
177
178     Initializes the internal stream state for compression. The fields
179   zalloc, zfree and opaque must be initialized before by the caller.
180   If zalloc and zfree are set to Z_NULL, deflateInit updates them to
181   use default allocation functions.
182
183     The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
184   1 gives best speed, 9 gives best compression, 0 gives no compression at
185   all (the input data is simply copied a block at a time).
186   Z_DEFAULT_COMPRESSION requests a default compromise between speed and
187   compression (currently equivalent to level 6).
188
189     deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
190   enough memory, Z_STREAM_ERROR if level is not a valid compression level,
191   Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
192   with the version assumed by the caller (ZLIB_VERSION).
193   msg is set to null if there is no error message.  deflateInit does not
194   perform any compression: this will be done by deflate().
195*/
196
197
198/*
199    deflate compresses as much data as possible, and stops when the input
200  buffer becomes empty or the output buffer becomes full. It may introduce some
201  output latency (reading input without producing any output) except when
202  forced to flush.
203
204    The detailed semantics are as follows. deflate performs one or both of the
205  following actions:
206
207  - Compress more input starting at next_in and update next_in and avail_in
208    accordingly. If not all input can be processed (because there is not
209    enough room in the output buffer), next_in and avail_in are updated and
210    processing will resume at this point for the next call of deflate().
211
212  - Provide more output starting at next_out and update next_out and avail_out
213    accordingly. This action is forced if the parameter flush is non zero.
214    Forcing flush frequently degrades the compression ratio, so this parameter
215    should be set only when necessary (in interactive applications).
216    Some output may be provided even if flush is not set.
217
218  Before the call of deflate(), the application should ensure that at least
219  one of the actions is possible, by providing more input and/or consuming
220  more output, and updating avail_in or avail_out accordingly; avail_out
221  should never be zero before the call. The application can consume the
222  compressed output when it wants, for example when the output buffer is full
223  (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
224  and with zero avail_out, it must be called again after making room in the
225  output buffer because there might be more output pending.
226
227    If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
228  flushed to the output buffer and the output is aligned on a byte boundary, so
229  that the decompressor can get all input data available so far. (In particular
230  avail_in is zero after the call if enough output space has been provided
231  before the call.)  Flushing may degrade compression for some compression
232  algorithms and so it should be used only when necessary.
233
234    If flush is set to Z_FULL_FLUSH, all output is flushed as with
235  Z_SYNC_FLUSH, and the compression state is reset so that decompression can
236  restart from this point if previous compressed data has been damaged or if
237  random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
238  the compression.
239
240    If deflate returns with avail_out == 0, this function must be called again
241  with the same value of the flush parameter and more output space (updated
242  avail_out), until the flush is complete (deflate returns with non-zero
243  avail_out).
244
245    If the parameter flush is set to Z_FINISH, pending input is processed,
246  pending output is flushed and deflate returns with Z_STREAM_END if there
247  was enough output space; if deflate returns with Z_OK, this function must be
248  called again with Z_FINISH and more output space (updated avail_out) but no
249  more input data, until it returns with Z_STREAM_END or an error. After
250  deflate has returned Z_STREAM_END, the only possible operations on the
251  stream are deflateReset or deflateEnd.
252
253    Z_FINISH can be used immediately after deflateInit if all the compression
254  is to be done in a single step. In this case, avail_out must be at least
255  0.1% larger than avail_in plus 12 bytes.  If deflate does not return
256  Z_STREAM_END, then it must be called again as described above.
257
258    deflate() sets strm->adler to the adler32 checksum of all input read
259  so far (that is, total_in bytes).
260
261    deflate() may update data_type if it can make a good guess about
262  the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
263  binary. This field is only for information purposes and does not affect
264  the compression algorithm in any manner.
265
266    deflate() returns Z_OK if some progress has been made (more input
267  processed or more output produced), Z_STREAM_END if all input has been
268  consumed and all output has been produced (only when flush is set to
269  Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
270  if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
271  (for example avail_in or avail_out was zero).
272*/
273
274
275/*
276     All dynamically allocated data structures for this stream are freed.
277   This function discards any unprocessed input and does not flush any
278   pending output.
279
280     deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
281   stream state was inconsistent, Z_DATA_ERROR if the stream was freed
282   prematurely (some input or output was discarded). In the error case,
283   msg may be set but then points to a static string (which must not be
284   deallocated).
285*/
286
287
288/*
289ZEXTERN(int)  inflateInit OF((z_streamp strm));
290
291     Initializes the internal stream state for decompression. The fields
292   next_in, avail_in, zalloc, zfree and opaque must be initialized before by
293   the caller. If next_in is not Z_NULL and avail_in is large enough (the exact
294   value depends on the compression method), inflateInit determines the
295   compression method from the zlib header and allocates all data structures
296   accordingly; otherwise the allocation will be deferred to the first call of
297   inflate.  If zalloc and zfree are set to Z_NULL, inflateInit updates them to
298   use default allocation functions.
299
300     inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
301   memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
302   version assumed by the caller.  msg is set to null if there is no error
303   message. inflateInit does not perform any decompression apart from reading
304   the zlib header if present: this will be done by inflate().  (So next_in and
305   avail_in may be modified, but next_out and avail_out are unchanged.)
306*/
307
308
309ZEXTERN(int) inflate OF((z_streamp strm, int flush));
310/*
311    inflate decompresses as much data as possible, and stops when the input
312  buffer becomes empty or the output buffer becomes full. It may some
313  introduce some output latency (reading input without producing any output)
314  except when forced to flush.
315
316  The detailed semantics are as follows. inflate performs one or both of the
317  following actions:
318
319  - Decompress more input starting at next_in and update next_in and avail_in
320    accordingly. If not all input can be processed (because there is not
321    enough room in the output buffer), next_in is updated and processing
322    will resume at this point for the next call of inflate().
323
324  - Provide more output starting at next_out and update next_out and avail_out
325    accordingly.  inflate() provides as much output as possible, until there
326    is no more input data or no more space in the output buffer (see below
327    about the flush parameter).
328
329  Before the call of inflate(), the application should ensure that at least
330  one of the actions is possible, by providing more input and/or consuming
331  more output, and updating the next_* and avail_* values accordingly.
332  The application can consume the uncompressed output when it wants, for
333  example when the output buffer is full (avail_out == 0), or after each
334  call of inflate(). If inflate returns Z_OK and with zero avail_out, it
335  must be called again after making room in the output buffer because there
336  might be more output pending.
337
338    If the parameter flush is set to Z_SYNC_FLUSH, inflate flushes as much
339  output as possible to the output buffer. The flushing behavior of inflate is
340  not specified for values of the flush parameter other than Z_SYNC_FLUSH
341  and Z_FINISH, but the current implementation actually flushes as much output
342  as possible anyway.
343
344    inflate() should normally be called until it returns Z_STREAM_END or an
345  error. However if all decompression is to be performed in a single step
346  (a single call of inflate), the parameter flush should be set to
347  Z_FINISH. In this case all pending input is processed and all pending
348  output is flushed; avail_out must be large enough to hold all the
349  uncompressed data. (The size of the uncompressed data may have been saved
350  by the compressor for this purpose.) The next operation on this stream must
351  be inflateEnd to deallocate the decompression state. The use of Z_FINISH
352  is never required, but can be used to inform inflate that a faster routine
353  may be used for the single inflate() call.
354
355     If a preset dictionary is needed at this point (see inflateSetDictionary
356  below), inflate sets strm-adler to the adler32 checksum of the
357  dictionary chosen by the compressor and returns Z_NEED_DICT; otherwise
358  it sets strm->adler to the adler32 checksum of all output produced
359  so far (that is, total_out bytes) and returns Z_OK, Z_STREAM_END or
360  an error code as described below. At the end of the stream, inflate()
361  checks that its computed adler32 checksum is equal to that saved by the
362  compressor and returns Z_STREAM_END only if the checksum is correct.
363
364    inflate() returns Z_OK if some progress has been made (more input processed
365  or more output produced), Z_STREAM_END if the end of the compressed data has
366  been reached and all uncompressed output has been produced, Z_NEED_DICT if a
367  preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
368  corrupted (input stream not conforming to the zlib format or incorrect
369  adler32 checksum), Z_STREAM_ERROR if the stream structure was inconsistent
370  (for example if next_in or next_out was NULL), Z_MEM_ERROR if there was not
371  enough memory, Z_BUF_ERROR if no progress is possible or if there was not
372  enough room in the output buffer when Z_FINISH is used. In the Z_DATA_ERROR
373  case, the application may then call inflateSync to look for a good
374  compression block.
375*/
376
377
378ZEXTERN(int)  inflateEnd OF((z_streamp strm));
379/*
380     All dynamically allocated data structures for this stream are freed.
381   This function discards any unprocessed input and does not flush any
382   pending output.
383
384     inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
385   was inconsistent. In the error case, msg may be set but then points to a
386   static string (which must not be deallocated).
387*/
388
389                        /* Advanced functions */
390
391/*
392    The following functions are needed only in some special applications.
393*/
394
395/*
396ZEXTERN(int)  deflateInit2 OF((z_streamp strm,
397                                     int  level,
398                                     int  method,
399                                     int  windowBits,
400                                     int  memLevel,
401                                     int  strategy));
402
403     This is another version of deflateInit with more compression options. The
404   fields next_in, zalloc, zfree and opaque must be initialized before by
405   the caller.
406
407     The method parameter is the compression method. It must be Z_DEFLATED in
408   this version of the library.
409
410     The windowBits parameter is the base two logarithm of the window size
411   (the size of the history buffer).  It should be in the range 8..15 for this
412   version of the library. Larger values of this parameter result in better
413   compression at the expense of memory usage. The default value is 15 if
414   deflateInit is used instead.
415
416     The memLevel parameter specifies how much memory should be allocated
417   for the internal compression state. memLevel=1 uses minimum memory but
418   is slow and reduces compression ratio; memLevel=9 uses maximum memory
419   for optimal speed. The default value is 8. See zconf.h for total memory
420   usage as a function of windowBits and memLevel.
421
422     The strategy parameter is used to tune the compression algorithm. Use the
423   value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
424   filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
425   string match).  Filtered data consists mostly of small values with a
426   somewhat random distribution. In this case, the compression algorithm is
427   tuned to compress them better. The effect of Z_FILTERED is to force more
428   Huffman coding and less string matching; it is somewhat intermediate
429   between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
430   the compression ratio but not the correctness of the compressed output even
431   if it is not set appropriately.
432
433      deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
434   memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid
435   method). msg is set to null if there is no error message.  deflateInit2 does
436   not perform any compression: this will be done by deflate().
437*/
438
439/*
440     Initializes the compression dictionary from the given byte sequence
441   without producing any compressed output. This function must be called
442   immediately after deflateInit, deflateInit2 or deflateReset, before any
443   call of deflate. The compressor and decompressor must use exactly the same
444   dictionary (see inflateSetDictionary).
445
446     The dictionary should consist of strings (byte sequences) that are likely
447   to be encountered later in the data to be compressed, with the most commonly
448   used strings preferably put towards the end of the dictionary. Using a
449   dictionary is most useful when the data to be compressed is short and can be
450   predicted with good accuracy; the data can then be compressed better than
451   with the default empty dictionary.
452
453     Depending on the size of the compression data structures selected by
454   deflateInit or deflateInit2, a part of the dictionary may in effect be
455   discarded, for example if the dictionary is larger than the window size in
456   deflate or deflate2. Thus the strings most likely to be useful should be
457   put at the end of the dictionary, not at the front.
458
459     Upon return of this function, strm->adler is set to the Adler32 value
460   of the dictionary; the decompressor may later use this value to determine
461   which dictionary has been used by the compressor. (The Adler32 value
462   applies to the whole dictionary even if only a subset of the dictionary is
463   actually used by the compressor.)
464
465     deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
466   parameter is invalid (such as NULL dictionary) or the stream state is
467   inconsistent (for example if deflate has already been called for this stream
468   or if the compression method is bsort). deflateSetDictionary does not
469   perform any compression: this will be done by deflate().
470*/
471
472/*
473     Sets the destination stream as a complete copy of the source stream.
474
475     This function can be useful when several compression strategies will be
476   tried, for example when there are several ways of pre-processing the input
477   data with a filter. The streams that will be discarded should then be freed
478   by calling deflateEnd.  Note that deflateCopy duplicates the internal
479   compression state which can be quite large, so this strategy is slow and
480   can consume lots of memory.
481
482     deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
483   enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
484   (such as zalloc being NULL). msg is left unchanged in both source and
485   destination.
486*/
487
488/*
489     This function is equivalent to deflateEnd followed by deflateInit,
490   but does not free and reallocate all the internal compression state.
491   The stream will keep the same compression level and any other attributes
492   that may have been set by deflateInit2.
493
494      deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
495   stream state was inconsistent (such as zalloc or state being NULL).
496*/
497
498/*
499     Dynamically update the compression level and compression strategy.  The
500   interpretation of level and strategy is as in deflateInit2.  This can be
501   used to switch between compression and straight copy of the input data, or
502   to switch to a different kind of input data requiring a different
503   strategy. If the compression level is changed, the input available so far
504   is compressed with the old level (and may be flushed); the new level will
505   take effect only at the next call of deflate().
506
507     Before the call of deflateParams, the stream state must be set as for
508   a call of deflate(), since the currently available input may have to
509   be compressed and flushed. In particular, strm->avail_out must be non-zero.
510
511     deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
512   stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
513   if strm->avail_out was zero.
514*/
515
516/*
517ZEXTERN(int)  inflateInit2 OF((z_streamp strm,
518                                     int  windowBits));
519
520     This is another version of inflateInit with an extra parameter. The
521   fields next_in, avail_in, zalloc, zfree and opaque must be initialized
522   before by the caller.
523
524     The windowBits parameter is the base two logarithm of the maximum window
525   size (the size of the history buffer).  It should be in the range 8..15 for
526   this version of the library. The default value is 15 if inflateInit is used
527   instead. If a compressed stream with a larger window size is given as
528   input, inflate() will return with the error code Z_DATA_ERROR instead of
529   trying to allocate a larger window.
530
531      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
532   memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
533   memLevel). msg is set to null if there is no error message.  inflateInit2
534   does not perform any decompression apart from reading the zlib header if
535   present: this will be done by inflate(). (So next_in and avail_in may be
536   modified, but next_out and avail_out are unchanged.)
537*/
538
539/*
540     Initializes the decompression dictionary from the given uncompressed byte
541   sequence. This function must be called immediately after a call of inflate
542   if this call returned Z_NEED_DICT. The dictionary chosen by the compressor
543   can be determined from the Adler32 value returned by this call of
544   inflate. The compressor and decompressor must use exactly the same
545   dictionary (see deflateSetDictionary).
546
547     inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
548   parameter is invalid (such as NULL dictionary) or the stream state is
549   inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
550   expected one (incorrect Adler32 value). inflateSetDictionary does not
551   perform any decompression: this will be done by subsequent calls of
552   inflate().
553*/
554
555/*
556    Skips invalid compressed data until a full flush point (see above the
557  description of deflate with Z_FULL_FLUSH) can be found, or until all
558  available input is skipped. No output is provided.
559
560    inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
561  if no more input was provided, Z_DATA_ERROR if no flush point has been found,
562  or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
563  case, the application may save the current current value of total_in which
564  indicates where valid compressed data was found. In the error case, the
565  application may repeatedly call inflateSync, providing more input each time,
566  until success or end of the input data.
567*/
568
569ZEXTERN(int)  inflateReset OF((z_streamp strm));
570/*
571     This function is equivalent to inflateEnd followed by inflateInit,
572   but does not free and reallocate all the internal decompression state.
573   The stream will keep attributes that may have been set by inflateInit2.
574
575      inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
576   stream state was inconsistent (such as zalloc or state being NULL).
577*/
578
579
580                        /* utility functions */
581
582/*
583     The following utility functions are implemented on top of the
584   basic stream-oriented functions. To simplify the interface, some
585   default options are assumed (compression level and memory usage,
586   standard memory allocation functions). The source code of these
587   utility functions can easily be modified if you need special options.
588*/
589
590/*
591     Compresses the source buffer into the destination buffer.  sourceLen is
592   the byte length of the source buffer. Upon entry, destLen is the total
593   size of the destination buffer, which must be at least 0.1% larger than
594   sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
595   compressed buffer.
596     This function can be used to compress a whole file at once if the
597   input file is mmap'ed.
598     compress returns Z_OK if success, Z_MEM_ERROR if there was not
599   enough memory, Z_BUF_ERROR if there was not enough room in the output
600   buffer.
601*/
602
603/*
604     Compresses the source buffer into the destination buffer. The level
605   parameter has the same meaning as in deflateInit.  sourceLen is the byte
606   length of the source buffer. Upon entry, destLen is the total size of the
607   destination buffer, which must be at least 0.1% larger than sourceLen plus
608   12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
609
610     compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
611   memory, Z_BUF_ERROR if there was not enough room in the output buffer,
612   Z_STREAM_ERROR if the level parameter is invalid.
613*/
614
615/*
616     Decompresses the source buffer into the destination buffer.  sourceLen is
617   the byte length of the source buffer. Upon entry, destLen is the total
618   size of the destination buffer, which must be large enough to hold the
619   entire uncompressed data. (The size of the uncompressed data must have
620   been saved previously by the compressor and transmitted to the decompressor
621   by some mechanism outside the scope of this compression library.)
622   Upon exit, destLen is the actual size of the compressed buffer.
623     This function can be used to decompress a whole file at once if the
624   input file is mmap'ed.
625
626     uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
627   enough memory, Z_BUF_ERROR if there was not enough room in the output
628   buffer, or Z_DATA_ERROR if the input data was corrupted.
629*/
630
631
632/*
633     Opens a gzip (.gz) file for reading or writing. The mode parameter
634   is as in fopen ("rb" or "wb") but can also include a compression level
635   ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for
636   Huffman only compression as in "wb1h". (See the description
637   of deflateInit2 for more information about the strategy parameter.)
638
639     gzopen can be used to read a file which is not in gzip format; in this
640   case gzread will directly read from the file without decompression.
641
642     gzopen returns NULL if the file could not be opened or if there was
643   insufficient memory to allocate the (de)compression state; errno
644   can be checked to distinguish the two cases (if errno is zero, the
645   zlib error is Z_MEM_ERROR).  */
646
647/*
648     gzdopen() associates a gzFile with the file descriptor fd.  File
649   descriptors are obtained from calls like open, dup, creat, pipe or
650   fileno (in the file has been previously opened with fopen).
651   The mode parameter is as in gzopen.
652     The next call of gzclose on the returned gzFile will also close the
653   file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
654   descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
655     gzdopen returns NULL if there was insufficient memory to allocate
656   the (de)compression state.
657*/
658
659/*
660     Dynamically update the compression level or strategy. See the description
661   of deflateInit2 for the meaning of these parameters.
662     gzsetparams returns Z_OK if success, or Z_STREAM_ERROR if the file was not
663   opened for writing.
664*/
665
666/*
667     Reads the given number of uncompressed bytes from the compressed file.
668   If the input file was not in gzip format, gzread copies the given number
669   of bytes into the buffer.
670     gzread returns the number of uncompressed bytes actually read (0 for
671   end of file, -1 for error). */
672
673/*
674     Writes the given number of uncompressed bytes into the compressed file.
675   gzwrite returns the number of uncompressed bytes actually written
676   (0 in case of error).
677*/
678
679/*
680     Converts, formats, and writes the args to the compressed file under
681   control of the format string, as in fprintf. gzprintf returns the number of
682   uncompressed bytes actually written (0 in case of error).
683*/
684
685/*
686      Writes the given null-terminated string to the compressed file, excluding
687   the terminating null character.
688      gzputs returns the number of characters written, or -1 in case of error.
689*/
690
691/*
692      Reads bytes from the compressed file until len-1 characters are read, or
693   a newline character is read and transferred to buf, or an end-of-file
694   condition is encountered.  The string is then terminated with a null
695   character.
696      gzgets returns buf, or Z_NULL in case of error.
697*/
698
699/*
700      Writes c, converted to an unsigned char, into the compressed file.
701   gzputc returns the value that was written, or -1 in case of error.
702*/
703
704/*
705      Reads one byte from the compressed file. gzgetc returns this byte
706   or -1 in case of end of file or error.
707*/
708
709/*
710     Flushes all pending output into the compressed file. The parameter
711   flush is as in the deflate() function. The return value is the zlib
712   error number (see function gzerror below). gzflush returns Z_OK if
713   the flush parameter is Z_FINISH and all output could be flushed.
714     gzflush should be called only when strictly necessary because it can
715   degrade compression.
716*/
717
718/*
719      Sets the starting position for the next gzread or gzwrite on the
720   given compressed file. The offset represents a number of bytes in the
721   uncompressed data stream. The whence parameter is defined as in lseek(2);
722   the value SEEK_END is not supported.
723     If the file is opened for reading, this function is emulated but can be
724   extremely slow. If the file is opened for writing, only forward seeks are
725   supported; gzseek then compresses a sequence of zeroes up to the new
726   starting position.
727
728      gzseek returns the resulting offset location as measured in bytes from
729   the beginning of the uncompressed stream, or -1 in case of error, in
730   particular if the file is opened for writing and the new starting position
731   would be before the current position.
732*/
733
734/*
735     Rewinds the given file. This function is supported only for reading.
736
737   gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET)
738*/
739
740/*
741     Returns the starting position for the next gzread or gzwrite on the
742   given compressed file. This position represents a number of bytes in the
743   uncompressed data stream.
744
745   gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
746*/
747
748/*
749     Returns 1 when EOF has previously been detected reading the given
750   input stream, otherwise zero.
751*/
752
753/*
754     Flushes all pending output if necessary, closes the compressed file
755   and deallocates all the (de)compression state. The return value is the zlib
756   error number (see function gzerror below).
757*/
758
759/*
760     Returns the error message for the last error which occurred on the
761   given compressed file. errnum is set to zlib error number. If an
762   error occurred in the file system and not in the compression library,
763   errnum is set to Z_ERRNO and the application may consult errno
764   to get the exact error code.
765*/
766
767                        /* checksum functions */
768
769/*
770     These functions are not related to compression but are exported
771   anyway because they might be useful in applications using the
772   compression library.
773*/
774
775ZEXTERN(uLong)  adler32 OF((uLong adler, const Bytef *buf, uInt len));
776
777/*
778     Update a running Adler-32 checksum with the bytes buf[0..len-1] and
779   return the updated checksum. If buf is NULL, this function returns
780   the required initial value for the checksum.
781   An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
782   much faster. Usage example:
783
784     uLong adler = adler32(0L, Z_NULL, 0);
785
786     while (read_buffer(buffer, length) != EOF) {
787       adler = adler32(adler, buffer, length);
788     }
789     if (adler != original_adler) error();
790*/
791
792/*
793     Update a running crc with the bytes buf[0..len-1] and return the updated
794   crc. If buf is NULL, this function returns the required initial value
795   for the crc. Pre- and post-conditioning (one's complement) is performed
796   within this function so it shouldn't be done by the application.
797   Usage example:
798
799     uLong crc = crc32(0L, Z_NULL, 0);
800
801     while (read_buffer(buffer, length) != EOF) {
802       crc = crc32(crc, buffer, length);
803     }
804     if (crc != original_crc) error();
805*/
806
807
808                        /* various hacks, don't look :) */
809
810/* deflateInit and inflateInit are macros to allow checking the zlib version
811 * and the compiler's view of z_stream:
812 */
813ZEXTERN(int)  inflateInit2_ OF((z_streamp strm, int  windowBits,
814                                      const char *version, int stream_size));
815#define deflateInit(strm, level) \
816        deflateInit_((strm), (level),       ZLIB_VERSION, sizeof(z_stream))
817#define inflateInit(strm) \
818        inflateInit_((strm),                ZLIB_VERSION, sizeof(z_stream))
819#define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
820        deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
821                      (strategy),           ZLIB_VERSION, sizeof(z_stream))
822#define inflateInit2(strm, windowBits) \
823        inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
824
825
826#ifdef __cplusplus
827}
828#endif
829
830#endif /* _ZLIB_H */