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First entry of Paradise Server 2.9 patch 10 Beta
author darius
date Sat, 06 Dec 1997 04:37:18 +0000
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1 /* zlib.h -- interface of the 'zlib' general purpose compression library
2 version 0.95, Aug 16th, 1995.
3
4 Copyright (C) 1995 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 gzip@prep.ai.mit.edu madler@alumni.caltech.edu
24 */
25
26 #ifndef _ZLIB_H
27 #define _ZLIB_H
28
29 #include "zconf.h"
30
31 #define ZLIB_VERSION "0.95"
32
33 /*
34 The 'zlib' compression library provides in-memory compression and
35 decompression functions, including integrity checks of the uncompressed
36 data. This version of the library supports only one compression method
37 (deflation) but other algorithms may be added later and will have the same
38 stream interface.
39
40 For compression the application must provide the output buffer and
41 may optionally provide the input buffer for optimization. For decompression,
42 the application must provide the input buffer and may optionally provide
43 the output buffer for optimization.
44
45 Compression can be done in a single step if the buffers are large
46 enough (for example if an input file is mmap'ed), or can be done by
47 repeated calls of the compression function. In the latter case, the
48 application must provide more input and/or consume the output
49 (providing more output space) before each call.
50 */
51
52 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
53 typedef void (*free_func) OF((voidpf opaque, voidpf address));
54
55 struct internal_state;
56
57 typedef struct z_stream_s {
58 Bytef *next_in; /* next input byte */
59 uInt avail_in; /* number of bytes available at next_in */
60 uLong total_in; /* total nb of input bytes read so far */
61
62 Bytef *next_out; /* next output byte should be put there */
63 uInt avail_out; /* remaining free space at next_out */
64 uLong total_out; /* total nb of bytes output so far */
65
66 char *msg; /* last error message, NULL if no error */
67 struct internal_state FAR *state; /* not visible by applications */
68
69 alloc_func zalloc; /* used to allocate the internal state */
70 free_func zfree; /* used to free the internal state */
71 voidp opaque; /* private data object passed to zalloc and zfree */
72
73 Byte data_type; /* best guess about the data type: ascii or binary */
74
75 } z_stream;
76
77 /*
78 The application must update next_in and avail_in when avail_in has
79 dropped to zero. It must update next_out and avail_out when avail_out
80 has dropped to zero. The application must initialize zalloc, zfree and
81 opaque before calling the init function. All other fields are set by the
82 compression library and must not be updated by the application.
83
84 The opaque value provided by the application will be passed as the first
85 parameter for calls of zalloc and zfree. This can be useful for custom
86 memory management. The compression library attaches no meaning to the
87 opaque value.
88
89 zalloc must return Z_NULL if there is not enough memory for the object.
90 On 16-bit systems, the functions zalloc and zfree must be able to allocate
91 exactly 65536 bytes, but will not be required to allocate more than this
92 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
93 pointers returned by zalloc for objects of exactly 65536 bytes *must*
94 have their offset normalized to zero. The default allocation function
95 provided by this library ensures this (see zutil.c). To reduce memory
96 requirements and avoid any allocation of 64K objects, at the expense of
97 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
98
99 The fields total_in and total_out can be used for statistics or
100 progress reports. After compression, total_in holds the total size of
101 the uncompressed data and may be saved for use in the decompressor
102 (particularly if the decompressor wants to decompress everything in
103 a single step).
104 */
105
106 /* constants */
107
108 #define Z_NO_FLUSH 0
109 #define Z_PARTIAL_FLUSH 1
110 #define Z_FULL_FLUSH 2
111 #define Z_SYNC_FLUSH 3 /* experimental: partial_flush + byte align */
112 #define Z_FINISH 4
113 /* See deflate() below for the usage of these constants */
114
115 #define Z_OK 0
116 #define Z_STREAM_END 1
117 #define Z_ERRNO (-1)
118 #define Z_STREAM_ERROR (-2)
119 #define Z_DATA_ERROR (-3)
120 #define Z_MEM_ERROR (-4)
121 #define Z_BUF_ERROR (-5)
122 /* error codes for the compression/decompression functions */
123
124 #define Z_BEST_SPEED 1
125 #define Z_BEST_COMPRESSION 9
126 #define Z_DEFAULT_COMPRESSION (-1)
127 /* compression levels */
128
129 #define Z_FILTERED 1
130 #define Z_HUFFMAN_ONLY 2
131 #define Z_DEFAULT_STRATEGY 0
132
133 #define Z_BINARY 0
134 #define Z_ASCII 1
135 #define Z_UNKNOWN 2
136 /* Used to set the data_type field */
137
138 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
139
140 extern char *zlib_version;
141 /* The application can compare zlib_version and ZLIB_VERSION for consistency.
142 If the first character differs, the library code actually used is
143 not compatible with the zlib.h header file used by the application.
144 */
145
146 /* basic functions */
147
148 extern int deflateInit OF((z_stream *strm, int level));
149 /*
150 Initializes the internal stream state for compression. The fields
151 zalloc, zfree and opaque must be initialized before by the caller.
152 If zalloc and zfree are set to Z_NULL, deflateInit updates them to
153 use default allocation functions.
154
155 The compression level must be Z_DEFAULT_COMPRESSION, or between 1 and 9:
156 1 gives best speed, 9 gives best compression. Z_DEFAULT_COMPRESSION requests
157 a default compromise between speed and compression (currently equivalent
158 to level 6).
159
160 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
161 enough memory, Z_STREAM_ERROR if level is not a valid compression level.
162 msg is set to null if there is no error message. deflateInit does not
163 perform any compression: this will be done by deflate().
164 */
165
166
167 extern int deflate OF((z_stream *strm, int flush));
168 /*
169 Performs one or both of the following actions:
170
171 - Compress more input starting at next_in and update next_in and avail_in
172 accordingly. If not all input can be processed (because there is not
173 enough room in the output buffer), next_in and avail_in are updated and
174 processing will resume at this point for the next call of deflate().
175
176 - Provide more output starting at next_out and update next_out and avail_out
177 accordingly. This action is forced if the parameter flush is non zero.
178 Forcing flush frequently degrades the compression ratio, so this parameter
179 should be set only when necessary (in interactive applications).
180 Some output may be provided even if flush is not set.
181
182 Before the call of deflate(), the application should ensure that at least
183 one of the actions is possible, by providing more input and/or consuming
184 more output, and updating avail_in or avail_out accordingly; avail_out
185 should never be zero before the call. The application can consume the
186 compressed output when it wants, for example when the output buffer is full
187 (avail_out == 0), or after each call of deflate().
188
189 If the parameter flush is set to Z_PARTIAL_FLUSH, the current compression
190 block is terminated and flushed to the output buffer so that the
191 decompressor can get all input data available so far. For method 9, a future
192 variant on method 8, the current block will be flushed but not terminated.
193 If flush is set to Z_FULL_FLUSH, the compression block is terminated, a
194 special marker is output and the compression dictionary is discarded; this
195 is useful to allow the decompressor to synchronize if one compressed block
196 has been damaged (see inflateSync below). Flushing degrades compression and
197 so should be used only when necessary. Using Z_FULL_FLUSH too often can
198 seriously degrade the compression. If deflate returns with avail_out == 0,
199 this function must be called again with the same value of the flush
200 parameter and more output space (updated avail_out), until the flush is
201 complete (deflate returns with non-zero avail_out).
202
203 If the parameter flush is set to Z_FINISH, all pending input is processed,
204 all pending output is flushed and deflate returns with Z_STREAM_END if there
205 was enough output space; if deflate returns with Z_OK, this function must be
206 called again with Z_FINISH and more output space (updated avail_out) but no
207 more input data, until it returns with Z_STREAM_END or an error. After
208 deflate has returned Z_STREAM_END, the only possible operations on the
209 stream are deflateReset or deflateEnd.
210
211 Z_FINISH can be used immediately after deflateInit if all the compression
212 is to be done in a single step. In this case, avail_out must be at least
213 0.1% larger than avail_in plus 12 bytes. If deflate does not return
214 Z_STREAM_END, then it must be called again as described above.
215
216 deflate() may update data_type if it can make a good guess about
217 the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
218 binary. This field is only for information purposes and does not affect
219 the compression algorithm in any manner.
220
221 deflate() returns Z_OK if some progress has been made (more input
222 processed or more output produced), Z_STREAM_END if all input has been
223 consumed and all output has been produced (only when flush is set to
224 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
225 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
226 */
227
228
229 extern int deflateEnd OF((z_stream *strm));
230 /*
231 All dynamically allocated data structures for this stream are freed.
232 This function discards any unprocessed input and does not flush any
233 pending output.
234
235 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
236 stream state was inconsistent. In the error case, msg may be set
237 but then points to a static string (which must not be deallocated).
238 */
239
240
241 extern int inflateInit OF((z_stream *strm));
242 /*
243 Initializes the internal stream state for decompression. The fields
244 zalloc and zfree must be initialized before by the caller. If zalloc and
245 zfree are set to Z_NULL, inflateInit updates them to use default allocation
246 functions.
247
248 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
249 enough memory. msg is set to null if there is no error message.
250 inflateInit does not perform any decompression: this will be done by
251 inflate().
252 */
253
254
255 extern int inflate OF((z_stream *strm, int flush));
256 /*
257 Performs one or both of the following actions:
258
259 - Decompress more input starting at next_in and update next_in and avail_in
260 accordingly. If not all input can be processed (because there is not
261 enough room in the output buffer), next_in is updated and processing
262 will resume at this point for the next call of inflate().
263
264 - Provide more output starting at next_out and update next_out and avail_out
265 accordingly. inflate() always provides as much output as possible
266 (until there is no more input data or no more space in the output buffer).
267
268 Before the call of inflate(), the application should ensure that at least
269 one of the actions is possible, by providing more input and/or consuming
270 more output, and updating the next_* and avail_* values accordingly.
271 The application can consume the uncompressed output when it wants, for
272 example when the output buffer is full (avail_out == 0), or after each
273 call of inflate().
274
275 If the parameter flush is set to Z_PARTIAL_FLUSH, inflate flushes as much
276 output as possible to the output buffer. The flushing behavior of inflate is
277 not specified for values of the flush parameter other than Z_PARTIAL_FLUSH
278 and Z_FINISH, but the current implementation actually flushes as much output
279 as possible anyway.
280
281 inflate() should normally be called until it returns Z_STREAM_END or an
282 error. However if all decompression is to be performed in a single step
283 (a single call of inflate), the parameter flush should be set to
284 Z_FINISH. In this case all pending input is processed and all pending
285 output is flushed; avail_out must be large enough to hold all the
286 uncompressed data. (The size of the uncompressed data may have been saved
287 by the compressor for this purpose.) The next operation on this stream must
288 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
289 is never required, but can be used to inform inflate that a faster routine
290 may be used for the single inflate() call.
291
292 inflate() returns Z_OK if some progress has been made (more input
293 processed or more output produced), Z_STREAM_END if the end of the
294 compressed data has been reached and all uncompressed output has been
295 produced, Z_DATA_ERROR if the input data was corrupted, Z_STREAM_ERROR if
296 the stream structure was inconsistent (for example if next_in or next_out
297 was NULL), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR if no
298 progress is possible or if there was not enough room in the output buffer
299 when Z_FINISH is used. In the Z_DATA_ERROR case, the application may then
300 call inflateSync to look for a good compression block.
301 */
302
303
304 extern int inflateEnd OF((z_stream *strm));
305 /*
306 All dynamically allocated data structures for this stream are freed.
307 This function discards any unprocessed input and does not flush any
308 pending output.
309
310 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
311 was inconsistent. In the error case, msg may be set but then points to a
312 static string (which must not be deallocated).
313 */
314
315 /* advanced functions */
316
317 /*
318 The following functions are needed only in some special applications.
319 */
320
321 extern int deflateInit2 OF((z_stream *strm,
322 int level,
323 int method,
324 int windowBits,
325 int memLevel,
326 int strategy));
327 /*
328 This is another version of deflateInit with more compression options. The
329 fields next_in, zalloc and zfree must be initialized before by the caller.
330
331 The method parameter is the compression method. It must be 8 in this
332 version of the library. (Method 9 will allow a 64K history buffer and
333 partial block flushes.)
334
335 The windowBits parameter is the base two logarithm of the window size
336 (the size of the history buffer). It should be in the range 8..15 for this
337 version of the library (the value 16 will be allowed for method 9). Larger
338 values of this parameter result in better compression at the expense of
339 memory usage. The default value is 15 if deflateInit is used instead.
340
341 The memLevel parameter specifies how much memory should be allocated
342 for the internal compression state. memLevel=1 uses minimum memory but
343 is slow and reduces compression ratio; memLevel=9 uses maximum memory
344 for optimal speed. The default value is 8. See zconf.h for total memory
345 usage as a function of windowBits and memLevel.
346
347 The strategy parameter is used to tune the compression algorithm. Use
348 the value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data
349 produced by a filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman
350 encoding only (no string match). Filtered data consists mostly of small
351 values with a somewhat random distribution. In this case, the
352 compression algorithm is tuned to compress them better. The strategy
353 parameter only affects the compression ratio but not the correctness of
354 the compressed output even if it is not set appropriately.
355
356 If next_in is not null, the library will use this buffer to hold also
357 some history information; the buffer must either hold the entire input
358 data, or have at least 1<<(windowBits+1) bytes and be writable. If next_in
359 is null, the library will allocate its own history buffer (and leave next_in
360 null). next_out need not be provided here but must be provided by the
361 application for the next call of deflate().
362
363 If the history buffer is provided by the application, next_in must
364 must never be changed by the application since the compressor maintains
365 information inside this buffer from call to call; the application
366 must provide more input only by increasing avail_in. next_in is always
367 reset by the library in this case.
368
369 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
370 not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
371 an invalid method). msg is set to null if there is no error message.
372 deflateInit2 does not perform any compression: this will be done by
373 deflate().
374 */
375
376 extern int deflateCopy OF((z_stream *dest,
377 z_stream *source));
378 /*
379 Sets the destination stream as a complete copy of the source stream. If
380 the source stream is using an application-supplied history buffer, a new
381 buffer is allocated for the destination stream. The compressed output
382 buffer is always application-supplied. It's the responsibility of the
383 application to provide the correct values of next_out and avail_out for the
384 next call of deflate.
385
386 This function is useful when several compression strategies will be
387 tried, for example when there are several ways of pre-processing the input
388 data with a filter. The streams that will be discarded should then be freed
389 by calling deflateEnd. Note that deflateCopy duplicates the internal
390 compression state which can be quite large, so this strategy is slow and
391 can consume lots of memory.
392
393 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
394 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
395 (such as zalloc being NULL). msg is left unchanged in both source and
396 destination.
397 */
398
399 extern int deflateReset OF((z_stream *strm));
400 /*
401 This function is equivalent to deflateEnd followed by deflateInit,
402 but does not free and reallocate all the internal compression state.
403 The stream will keep the same compression level and any other attributes
404 that may have been set by deflateInit2.
405
406 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
407 stream state was inconsistent (such as zalloc or state being NULL).
408 */
409
410 extern int inflateInit2 OF((z_stream *strm,
411 int windowBits));
412 /*
413 This is another version of inflateInit with more compression options. The
414 fields next_out, zalloc and zfree must be initialized before by the caller.
415
416 The windowBits parameter is the base two logarithm of the maximum window
417 size (the size of the history buffer). It should be in the range 8..15 for
418 this version of the library (the value 16 will be allowed soon). The
419 default value is 15 if inflateInit is used instead. If a compressed stream
420 with a larger window size is given as input, inflate() will return with
421 the error code Z_DATA_ERROR instead of trying to allocate a larger window.
422
423 If next_out is not null, the library will use this buffer for the history
424 buffer; the buffer must either be large enough to hold the entire output
425 data, or have at least 1<<windowBits bytes. If next_out is null, the
426 library will allocate its own buffer (and leave next_out null). next_in
427 need not be provided here but must be provided by the application for the
428 next call of inflate().
429
430 If the history buffer is provided by the application, next_out must
431 never be changed by the application since the decompressor maintains
432 history information inside this buffer from call to call; the application
433 can only reset next_out to the beginning of the history buffer when
434 avail_out is zero and all output has been consumed.
435
436 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
437 not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
438 windowBits < 8). msg is set to null if there is no error message.
439 inflateInit2 does not perform any decompression: this will be done by
440 inflate().
441 */
442
443 extern int inflateSync OF((z_stream *strm));
444 /*
445 Skips invalid compressed data until the special marker (see deflate()
446 above) can be found, or until all available input is skipped. No output
447 is provided.
448
449 inflateSync returns Z_OK if the special marker has been found, Z_BUF_ERROR
450 if no more input was provided, Z_DATA_ERROR if no marker has been found,
451 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
452 case, the application may save the current current value of total_in which
453 indicates where valid compressed data was found. In the error case, the
454 application may repeatedly call inflateSync, providing more input each time,
455 until success or end of the input data.
456 */
457
458 extern int inflateReset OF((z_stream *strm));
459 /*
460 This function is equivalent to inflateEnd followed by inflateInit,
461 but does not free and reallocate all the internal decompression state.
462 The stream will keep attributes that may have been set by inflateInit2.
463
464 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
465 stream state was inconsistent (such as zalloc or state being NULL).
466 */
467
468
469 /* utility functions */
470
471 /*
472 The following utility functions are implemented on top of the
473 basic stream-oriented functions. To simplify the interface, some
474 default options are assumed (compression level, window size,
475 standard memory allocation functions). The source code of these
476 utility functions can easily be modified if you need special options.
477 */
478
479 extern int compress OF((Bytef *dest, uLongf *destLen,
480 Bytef *source, uLong sourceLen));
481 /*
482 Compresses the source buffer into the destination buffer. sourceLen is
483 the byte length of the source buffer. Upon entry, destLen is the total
484 size of the destination buffer, which must be at least 0.1% larger than
485 sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
486 compressed buffer.
487 This function can be used to compress a whole file at once if the
488 input file is mmap'ed.
489 compress returns Z_OK if success, Z_MEM_ERROR if there was not
490 enough memory, Z_BUF_ERROR if there was not enough room in the output
491 buffer.
492 */
493
494 extern int uncompress OF((Bytef *dest, uLongf *destLen,
495 Bytef *source, uLong sourceLen));
496 /*
497 Decompresses the source buffer into the destination buffer. sourceLen is
498 the byte length of the source buffer. Upon entry, destLen is the total
499 size of the destination buffer, which must be large enough to hold the
500 entire uncompressed data. (The size of the uncompressed data must have
501 been saved previously by the compressor and transmitted to the decompressor
502 by some mechanism outside the scope of this compression library.)
503 Upon exit, destLen is the actual size of the compressed buffer.
504 This function can be used to decompress a whole file at once if the
505 input file is mmap'ed.
506
507 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
508 enough memory, Z_BUF_ERROR if there was not enough room in the output
509 buffer, or Z_DATA_ERROR if the input data was corrupted.
510 */
511
512
513 typedef voidp gzFile;
514
515 extern gzFile gzopen OF((char *path, char *mode));
516 /*
517 Opens a gzip (.gz) file for reading or writing. The mode parameter
518 is as in fopen ("rb" or "wb") but can also include a compression level
519 ("wb9"). gzopen can be used to read a file which is not in gzip format;
520 in this case gzread will directly read from the file without decompression.
521 gzopen returns NULL if the file could not be opened or if there was
522 insufficient memory to allocate the (de)compression state; errno
523 can be checked to distinguish the two cases (if errno is zero, the
524 zlib error is Z_MEM_ERROR).
525 */
526
527 extern gzFile gzdopen OF((int fd, char *mode));
528 /*
529 gzdopen() associates a gzFile with the file descriptor fd. File
530 descriptors are obtained from calls like open, dup, creat, or pipe.
531 The mode parameter is as in fopen ("rb" or "wb").
532 gzdopen returns NULL if there was insufficient memory to allocate
533 the (de)compression state.
534 */
535
536 extern int gzread OF((gzFile file, voidp buf, unsigned len));
537 /*
538 Reads the given number of uncompressed bytes from the compressed file.
539 If the input file was not in gzip format, gzread copies the given number
540 of bytes into the buffer.
541 gzread returns the number of uncompressed bytes actually read (0 for
542 end of file, -1 for error). */
543
544 extern int gzwrite OF((gzFile file, voidp buf, unsigned len));
545 /*
546 Writes the given number of uncompressed bytes into the compressed file.
547 gzwrite returns the number of uncompressed bytes actually written
548 (0 in case of error).
549 */
550
551 extern int gzflush OF((gzFile file, int flush));
552 /*
553 Flushes all pending output into the compressed file. The parameter
554 flush is as in the deflate() function. The return value is the zlib
555 error number (see function gzerror below). gzflush returns Z_OK if
556 the flush parameter is Z_FINISH and all output could be flushed.
557 gzflush should be called only when strictly necessary because it can
558 degrade compression.
559 */
560
561 extern int gzclose OF((gzFile file));
562 /*
563 Flushes all pending output if necessary, closes the compressed file
564 and deallocates all the (de)compression state. The return value is the zlib
565 error number (see function gzerror below).
566 */
567
568 extern char* gzerror OF((gzFile file, int *errnum));
569 /*
570 Returns the error message for the last error which occurred on the
571 given compressed file. errnum is set to zlib error number. If an
572 error occurred in the file system and not in the compression library,
573 errnum is set to Z_ERRNO and the application may consult errno
574 to get the exact error code.
575 */
576
577 /* checksum functions */
578
579 /*
580 These functions are not related to compression but are exported
581 anyway because they might be useful in applications using the
582 compression library.
583 */
584
585 extern uLong adler32 OF((uLong adler, Bytef *buf, uInt len));
586
587 /*
588 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
589 return the updated checksum. If buf is NULL, this function returns
590 the required initial value for the checksum.
591 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
592 much faster. Usage example:
593
594 uLong adler = adler32(0L, Z_NULL, 0);
595
596 while (read_buffer(buffer, length) != EOF) {
597 adler = adler32(adler, buffer, length);
598 }
599 if (adler != original_adler) error();
600 */
601
602 extern uLong crc32 OF((uLong crc, Bytef *buf, uInt len));
603 /*
604 Update a running crc with the bytes buf[0..len-1] and return the updated
605 crc. If buf is NULL, this function returns the required initial value
606 for the crc. Pre- and post-conditioning (one's complement) is performed
607 within this function so it shouldn't be done by the application.
608 Usage example:
609
610 uLong crc = crc32(0L, Z_NULL, 0);
611
612 while (read_buffer(buffer, length) != EOF) {
613 crc = crc32(crc, buffer, length);
614 }
615 if (crc != original_crc) error();
616 */
617
618 #ifndef _Z_UTIL_H
619 struct internal_state {int dummy;}; /* hack for buggy compilers */
620 #endif
621
622 #endif /* _ZLIB_H */