zlib.h 27 KB

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  1. /* $Id: zlib.h,v 1.1 1999/03/23 03:21:58 paulus Exp $ */
  2. /*
  3. * This file is derived from zlib.h and zconf.h from the zlib-0.95
  4. * distribution by Jean-loup Gailly and Mark Adler, with some additions
  5. * by Paul Mackerras to aid in implementing Deflate compression and
  6. * decompression for PPP packets.
  7. */
  8. /* zlib.h -- interface of the 'zlib' general purpose compression library
  9. version 0.95, Aug 16th, 1995.
  10. Copyright (C) 1995 Jean-loup Gailly and Mark Adler
  11. This software is provided 'as-is', without any express or implied
  12. warranty. In no event will the authors be held liable for any damages
  13. arising from the use of this software.
  14. Permission is granted to anyone to use this software for any purpose,
  15. including commercial applications, and to alter it and redistribute it
  16. freely, subject to the following restrictions:
  17. 1. The origin of this software must not be misrepresented; you must not
  18. claim that you wrote the original software. If you use this software
  19. in a product, an acknowledgment in the product documentation would be
  20. appreciated but is not required.
  21. 2. Altered source versions must be plainly marked as such, and must not be
  22. misrepresented as being the original software.
  23. 3. This notice may not be removed or altered from any source distribution.
  24. Jean-loup Gailly Mark Adler
  25. gzip@prep.ai.mit.edu madler@alumni.caltech.edu
  26. */
  27. #ifndef _ZLIB_H
  28. #define _ZLIB_H
  29. /* #include "zconf.h" */ /* included directly here */
  30. /* zconf.h -- configuration of the zlib compression library
  31. * Copyright (C) 1995 Jean-loup Gailly.
  32. * For conditions of distribution and use, see copyright notice in zlib.h
  33. */
  34. /* From: zconf.h,v 1.12 1995/05/03 17:27:12 jloup Exp */
  35. /*
  36. The library does not install any signal handler. It is recommended to
  37. add at least a handler for SIGSEGV when decompressing; the library checks
  38. the consistency of the input data whenever possible but may go nuts
  39. for some forms of corrupted input.
  40. */
  41. /*
  42. * Compile with -DMAXSEG_64K if the alloc function cannot allocate more
  43. * than 64k bytes at a time (needed on systems with 16-bit int).
  44. * Compile with -DUNALIGNED_OK if it is OK to access shorts or ints
  45. * at addresses which are not a multiple of their size.
  46. * Under DOS, -DFAR=far or -DFAR=__far may be needed.
  47. */
  48. #ifndef STDC
  49. # if defined(MSDOS) || defined(__STDC__) || defined(__cplusplus)
  50. # define STDC
  51. # endif
  52. #endif
  53. #ifdef __MWERKS__ /* Metrowerks CodeWarrior declares fileno() in unix.h */
  54. # include <unix.h>
  55. #endif
  56. /* Maximum value for memLevel in deflateInit2 */
  57. #ifndef MAX_MEM_LEVEL
  58. # ifdef MAXSEG_64K
  59. # define MAX_MEM_LEVEL 8
  60. # else
  61. # define MAX_MEM_LEVEL 9
  62. # endif
  63. #endif
  64. #ifndef FAR
  65. # define FAR
  66. #endif
  67. /* Maximum value for windowBits in deflateInit2 and inflateInit2 */
  68. #ifndef MAX_WBITS
  69. # define MAX_WBITS 15 /* 32K LZ77 window */
  70. #endif
  71. /* The memory requirements for deflate are (in bytes):
  72. 1 << (windowBits+2) + 1 << (memLevel+9)
  73. that is: 128K for windowBits=15 + 128K for memLevel = 8 (default values)
  74. plus a few kilobytes for small objects. For example, if you want to reduce
  75. the default memory requirements from 256K to 128K, compile with
  76. make CFLAGS="-O -DMAX_WBITS=14 -DMAX_MEM_LEVEL=7"
  77. Of course this will generally degrade compression (there's no free lunch).
  78. The memory requirements for inflate are (in bytes) 1 << windowBits
  79. that is, 32K for windowBits=15 (default value) plus a few kilobytes
  80. for small objects.
  81. */
  82. /* Type declarations */
  83. #ifndef OF /* function prototypes */
  84. # ifdef STDC
  85. # define OF(args) args
  86. # else
  87. # define OF(args) ()
  88. # endif
  89. #endif
  90. typedef unsigned char Byte; /* 8 bits */
  91. typedef unsigned int uInt; /* 16 bits or more */
  92. typedef unsigned long uLong; /* 32 bits or more */
  93. typedef Byte FAR Bytef;
  94. typedef char FAR charf;
  95. typedef int FAR intf;
  96. typedef uInt FAR uIntf;
  97. typedef uLong FAR uLongf;
  98. #ifdef STDC
  99. typedef void FAR *voidpf;
  100. typedef void *voidp;
  101. #else
  102. typedef Byte FAR *voidpf;
  103. typedef Byte *voidp;
  104. #endif
  105. /* end of original zconf.h */
  106. #define ZLIB_VERSION "0.95P"
  107. /*
  108. The 'zlib' compression library provides in-memory compression and
  109. decompression functions, including integrity checks of the uncompressed
  110. data. This version of the library supports only one compression method
  111. (deflation) but other algorithms may be added later and will have the same
  112. stream interface.
  113. For compression the application must provide the output buffer and
  114. may optionally provide the input buffer for optimization. For decompression,
  115. the application must provide the input buffer and may optionally provide
  116. the output buffer for optimization.
  117. Compression can be done in a single step if the buffers are large
  118. enough (for example if an input file is mmap'ed), or can be done by
  119. repeated calls of the compression function. In the latter case, the
  120. application must provide more input and/or consume the output
  121. (providing more output space) before each call.
  122. */
  123. typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
  124. typedef void (*free_func) OF((voidpf opaque, voidpf address, uInt nbytes));
  125. struct internal_state;
  126. typedef struct z_stream_s {
  127. Bytef *next_in; /* next input byte */
  128. uInt avail_in; /* number of bytes available at next_in */
  129. uLong total_in; /* total nb of input bytes read so far */
  130. Bytef *next_out; /* next output byte should be put there */
  131. uInt avail_out; /* remaining free space at next_out */
  132. uLong total_out; /* total nb of bytes output so far */
  133. char *msg; /* last error message, NULL if no error */
  134. struct internal_state FAR *state; /* not visible by applications */
  135. alloc_func zalloc; /* used to allocate the internal state */
  136. free_func zfree; /* used to free the internal state */
  137. voidp opaque; /* private data object passed to zalloc and zfree */
  138. Byte data_type; /* best guess about the data type: ascii or binary */
  139. } z_stream;
  140. /*
  141. The application must update next_in and avail_in when avail_in has
  142. dropped to zero. It must update next_out and avail_out when avail_out
  143. has dropped to zero. The application must initialize zalloc, zfree and
  144. opaque before calling the init function. All other fields are set by the
  145. compression library and must not be updated by the application.
  146. The opaque value provided by the application will be passed as the first
  147. parameter for calls of zalloc and zfree. This can be useful for custom
  148. memory management. The compression library attaches no meaning to the
  149. opaque value.
  150. zalloc must return Z_NULL if there is not enough memory for the object.
  151. On 16-bit systems, the functions zalloc and zfree must be able to allocate
  152. exactly 65536 bytes, but will not be required to allocate more than this
  153. if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
  154. pointers returned by zalloc for objects of exactly 65536 bytes *must*
  155. have their offset normalized to zero. The default allocation function
  156. provided by this library ensures this (see zutil.c). To reduce memory
  157. requirements and avoid any allocation of 64K objects, at the expense of
  158. compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
  159. The fields total_in and total_out can be used for statistics or
  160. progress reports. After compression, total_in holds the total size of
  161. the uncompressed data and may be saved for use in the decompressor
  162. (particularly if the decompressor wants to decompress everything in
  163. a single step).
  164. */
  165. /* constants */
  166. #define Z_NO_FLUSH 0
  167. #define Z_PARTIAL_FLUSH 1
  168. #define Z_FULL_FLUSH 2
  169. #define Z_SYNC_FLUSH 3 /* experimental: partial_flush + byte align */
  170. #define Z_FINISH 4
  171. #define Z_PACKET_FLUSH 5
  172. /* See deflate() below for the usage of these constants */
  173. #define Z_OK 0
  174. #define Z_STREAM_END 1
  175. #define Z_ERRNO (-1)
  176. #define Z_STREAM_ERROR (-2)
  177. #define Z_DATA_ERROR (-3)
  178. #define Z_MEM_ERROR (-4)
  179. #define Z_BUF_ERROR (-5)
  180. /* error codes for the compression/decompression functions */
  181. #define Z_BEST_SPEED 1
  182. #define Z_BEST_COMPRESSION 9
  183. #define Z_DEFAULT_COMPRESSION (-1)
  184. /* compression levels */
  185. #define Z_FILTERED 1
  186. #define Z_HUFFMAN_ONLY 2
  187. #define Z_DEFAULT_STRATEGY 0
  188. #define Z_BINARY 0
  189. #define Z_ASCII 1
  190. #define Z_UNKNOWN 2
  191. /* Used to set the data_type field */
  192. #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
  193. extern char *zlib_version;
  194. /* The application can compare zlib_version and ZLIB_VERSION for consistency.
  195. If the first character differs, the library code actually used is
  196. not compatible with the zlib.h header file used by the application.
  197. */
  198. /* basic functions */
  199. extern int deflateInit OF((z_stream *strm, int level));
  200. /*
  201. Initializes the internal stream state for compression. The fields
  202. zalloc, zfree and opaque must be initialized before by the caller.
  203. If zalloc and zfree are set to Z_NULL, deflateInit updates them to
  204. use default allocation functions.
  205. The compression level must be Z_DEFAULT_COMPRESSION, or between 1 and 9:
  206. 1 gives best speed, 9 gives best compression. Z_DEFAULT_COMPRESSION requests
  207. a default compromise between speed and compression (currently equivalent
  208. to level 6).
  209. deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
  210. enough memory, Z_STREAM_ERROR if level is not a valid compression level.
  211. msg is set to null if there is no error message. deflateInit does not
  212. perform any compression: this will be done by deflate().
  213. */
  214. extern int deflate OF((z_stream *strm, int flush));
  215. /*
  216. Performs one or both of the following actions:
  217. - Compress more input starting at next_in and update next_in and avail_in
  218. accordingly. If not all input can be processed (because there is not
  219. enough room in the output buffer), next_in and avail_in are updated and
  220. processing will resume at this point for the next call of deflate().
  221. - Provide more output starting at next_out and update next_out and avail_out
  222. accordingly. This action is forced if the parameter flush is non zero.
  223. Forcing flush frequently degrades the compression ratio, so this parameter
  224. should be set only when necessary (in interactive applications).
  225. Some output may be provided even if flush is not set.
  226. Before the call of deflate(), the application should ensure that at least
  227. one of the actions is possible, by providing more input and/or consuming
  228. more output, and updating avail_in or avail_out accordingly; avail_out
  229. should never be zero before the call. The application can consume the
  230. compressed output when it wants, for example when the output buffer is full
  231. (avail_out == 0), or after each call of deflate().
  232. If the parameter flush is set to Z_PARTIAL_FLUSH, the current compression
  233. block is terminated and flushed to the output buffer so that the
  234. decompressor can get all input data available so far. For method 9, a future
  235. variant on method 8, the current block will be flushed but not terminated.
  236. If flush is set to Z_FULL_FLUSH, the compression block is terminated, a
  237. special marker is output and the compression dictionary is discarded; this
  238. is useful to allow the decompressor to synchronize if one compressed block
  239. has been damaged (see inflateSync below). Flushing degrades compression and
  240. so should be used only when necessary. Using Z_FULL_FLUSH too often can
  241. seriously degrade the compression. If deflate returns with avail_out == 0,
  242. this function must be called again with the same value of the flush
  243. parameter and more output space (updated avail_out), until the flush is
  244. complete (deflate returns with non-zero avail_out).
  245. If the parameter flush is set to Z_PACKET_FLUSH, the compression
  246. block is terminated, and a zero-length stored block is output,
  247. omitting the length bytes (the effect of this is that the 3-bit type
  248. code 000 for a stored block is output, and the output is then
  249. byte-aligned). This is designed for use at the end of a PPP packet.
  250. In addition, if the current compression block contains all the data
  251. since the last Z_PACKET_FLUSH, it is never output as a stored block.
  252. If the current compression block output as a static or dynamic block
  253. would not be at least `minCompression' bytes smaller than the
  254. original data, then nothing is output for that block. (The type
  255. code for the zero-length stored block is still output, resulting in
  256. a single zero byte being output for the whole packet.)
  257. `MinCompression' is a parameter to deflateInit2, or 0 if deflateInit
  258. is used.
  259. If the parameter flush is set to Z_FINISH, all pending input is processed,
  260. all pending output is flushed and deflate returns with Z_STREAM_END if there
  261. was enough output space; if deflate returns with Z_OK, this function must be
  262. called again with Z_FINISH and more output space (updated avail_out) but no
  263. more input data, until it returns with Z_STREAM_END or an error. After
  264. deflate has returned Z_STREAM_END, the only possible operations on the
  265. stream are deflateReset or deflateEnd.
  266. Z_FINISH can be used immediately after deflateInit if all the compression
  267. is to be done in a single step. In this case, avail_out must be at least
  268. 0.1% larger than avail_in plus 12 bytes. If deflate does not return
  269. Z_STREAM_END, then it must be called again as described above.
  270. deflate() may update data_type if it can make a good guess about
  271. the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
  272. binary. This field is only for information purposes and does not affect
  273. the compression algorithm in any manner.
  274. deflate() returns Z_OK if some progress has been made (more input
  275. processed or more output produced), Z_STREAM_END if all input has been
  276. consumed and all output has been produced (only when flush is set to
  277. Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
  278. if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
  279. */
  280. extern int deflateEnd OF((z_stream *strm));
  281. /*
  282. All dynamically allocated data structures for this stream are freed.
  283. This function discards any unprocessed input and does not flush any
  284. pending output.
  285. deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
  286. stream state was inconsistent. In the error case, msg may be set
  287. but then points to a static string (which must not be deallocated).
  288. */
  289. extern int inflateInit OF((z_stream *strm));
  290. /*
  291. Initializes the internal stream state for decompression. The fields
  292. zalloc and zfree must be initialized before by the caller. If zalloc and
  293. zfree are set to Z_NULL, inflateInit updates them to use default allocation
  294. functions.
  295. inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
  296. enough memory. msg is set to null if there is no error message.
  297. inflateInit does not perform any decompression: this will be done by
  298. inflate().
  299. */
  300. extern int inflate OF((z_stream *strm, int flush));
  301. /*
  302. Performs one or both of the following actions:
  303. - Decompress more input starting at next_in and update next_in and avail_in
  304. accordingly. If not all input can be processed (because there is not
  305. enough room in the output buffer), next_in is updated and processing
  306. will resume at this point for the next call of inflate().
  307. - Provide more output starting at next_out and update next_out and avail_out
  308. accordingly. inflate() always provides as much output as possible
  309. (until there is no more input data or no more space in the output buffer).
  310. Before the call of inflate(), the application should ensure that at least
  311. one of the actions is possible, by providing more input and/or consuming
  312. more output, and updating the next_* and avail_* values accordingly.
  313. The application can consume the uncompressed output when it wants, for
  314. example when the output buffer is full (avail_out == 0), or after each
  315. call of inflate().
  316. If the parameter flush is set to Z_PARTIAL_FLUSH or Z_PACKET_FLUSH,
  317. inflate flushes as much output as possible to the output buffer. The
  318. flushing behavior of inflate is not specified for values of the flush
  319. parameter other than Z_PARTIAL_FLUSH, Z_PACKET_FLUSH or Z_FINISH, but the
  320. current implementation actually flushes as much output as possible
  321. anyway. For Z_PACKET_FLUSH, inflate checks that once all the input data
  322. has been consumed, it is expecting to see the length field of a stored
  323. block; if not, it returns Z_DATA_ERROR.
  324. inflate() should normally be called until it returns Z_STREAM_END or an
  325. error. However if all decompression is to be performed in a single step
  326. (a single call of inflate), the parameter flush should be set to
  327. Z_FINISH. In this case all pending input is processed and all pending
  328. output is flushed; avail_out must be large enough to hold all the
  329. uncompressed data. (The size of the uncompressed data may have been saved
  330. by the compressor for this purpose.) The next operation on this stream must
  331. be inflateEnd to deallocate the decompression state. The use of Z_FINISH
  332. is never required, but can be used to inform inflate that a faster routine
  333. may be used for the single inflate() call.
  334. inflate() returns Z_OK if some progress has been made (more input
  335. processed or more output produced), Z_STREAM_END if the end of the
  336. compressed data has been reached and all uncompressed output has been
  337. produced, Z_DATA_ERROR if the input data was corrupted, Z_STREAM_ERROR if
  338. the stream structure was inconsistent (for example if next_in or next_out
  339. was NULL), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR if no
  340. progress is possible or if there was not enough room in the output buffer
  341. when Z_FINISH is used. In the Z_DATA_ERROR case, the application may then
  342. call inflateSync to look for a good compression block. */
  343. extern int inflateEnd OF((z_stream *strm));
  344. /*
  345. All dynamically allocated data structures for this stream are freed.
  346. This function discards any unprocessed input and does not flush any
  347. pending output.
  348. inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
  349. was inconsistent. In the error case, msg may be set but then points to a
  350. static string (which must not be deallocated).
  351. */
  352. /* advanced functions */
  353. /*
  354. The following functions are needed only in some special applications.
  355. */
  356. extern int deflateInit2 OF((z_stream *strm,
  357. int level,
  358. int method,
  359. int windowBits,
  360. int memLevel,
  361. int strategy,
  362. int minCompression));
  363. /*
  364. This is another version of deflateInit with more compression options. The
  365. fields next_in, zalloc and zfree must be initialized before by the caller.
  366. The method parameter is the compression method. It must be 8 in this
  367. version of the library. (Method 9 will allow a 64K history buffer and
  368. partial block flushes.)
  369. The windowBits parameter is the base two logarithm of the window size
  370. (the size of the history buffer). It should be in the range 8..15 for this
  371. version of the library (the value 16 will be allowed for method 9). Larger
  372. values of this parameter result in better compression at the expense of
  373. memory usage. The default value is 15 if deflateInit is used instead.
  374. The memLevel parameter specifies how much memory should be allocated
  375. for the internal compression state. memLevel=1 uses minimum memory but
  376. is slow and reduces compression ratio; memLevel=9 uses maximum memory
  377. for optimal speed. The default value is 8. See zconf.h for total memory
  378. usage as a function of windowBits and memLevel.
  379. The strategy parameter is used to tune the compression algorithm. Use
  380. the value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data
  381. produced by a filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman
  382. encoding only (no string match). Filtered data consists mostly of small
  383. values with a somewhat random distribution. In this case, the
  384. compression algorithm is tuned to compress them better. The strategy
  385. parameter only affects the compression ratio but not the correctness of
  386. the compressed output even if it is not set appropriately.
  387. The minCompression parameter specifies the minimum reduction in size
  388. required for a compressed block to be output when Z_PACKET_FLUSH is
  389. used (see the description of deflate above).
  390. If next_in is not null, the library will use this buffer to hold also
  391. some history information; the buffer must either hold the entire input
  392. data, or have at least 1<<(windowBits+1) bytes and be writable. If next_in
  393. is null, the library will allocate its own history buffer (and leave next_in
  394. null). next_out need not be provided here but must be provided by the
  395. application for the next call of deflate().
  396. If the history buffer is provided by the application, next_in must
  397. must never be changed by the application since the compressor maintains
  398. information inside this buffer from call to call; the application
  399. must provide more input only by increasing avail_in. next_in is always
  400. reset by the library in this case.
  401. deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
  402. not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
  403. an invalid method). msg is set to null if there is no error message.
  404. deflateInit2 does not perform any compression: this will be done by
  405. deflate().
  406. */
  407. extern int deflateCopy OF((z_stream *dest,
  408. z_stream *source));
  409. /*
  410. Sets the destination stream as a complete copy of the source stream. If
  411. the source stream is using an application-supplied history buffer, a new
  412. buffer is allocated for the destination stream. The compressed output
  413. buffer is always application-supplied. It's the responsibility of the
  414. application to provide the correct values of next_out and avail_out for the
  415. next call of deflate.
  416. This function is useful when several compression strategies will be
  417. tried, for example when there are several ways of pre-processing the input
  418. data with a filter. The streams that will be discarded should then be freed
  419. by calling deflateEnd. Note that deflateCopy duplicates the internal
  420. compression state which can be quite large, so this strategy is slow and
  421. can consume lots of memory.
  422. deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
  423. enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
  424. (such as zalloc being NULL). msg is left unchanged in both source and
  425. destination.
  426. */
  427. extern int deflateReset OF((z_stream *strm));
  428. /*
  429. This function is equivalent to deflateEnd followed by deflateInit,
  430. but does not free and reallocate all the internal compression state.
  431. The stream will keep the same compression level and any other attributes
  432. that may have been set by deflateInit2.
  433. deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
  434. stream state was inconsistent (such as zalloc or state being NULL).
  435. */
  436. extern int inflateInit2 OF((z_stream *strm,
  437. int windowBits));
  438. /*
  439. This is another version of inflateInit with more compression options. The
  440. fields next_out, zalloc and zfree must be initialized before by the caller.
  441. The windowBits parameter is the base two logarithm of the maximum window
  442. size (the size of the history buffer). It should be in the range 8..15 for
  443. this version of the library (the value 16 will be allowed soon). The
  444. default value is 15 if inflateInit is used instead. If a compressed stream
  445. with a larger window size is given as input, inflate() will return with
  446. the error code Z_DATA_ERROR instead of trying to allocate a larger window.
  447. If next_out is not null, the library will use this buffer for the history
  448. buffer; the buffer must either be large enough to hold the entire output
  449. data, or have at least 1<<windowBits bytes. If next_out is null, the
  450. library will allocate its own buffer (and leave next_out null). next_in
  451. need not be provided here but must be provided by the application for the
  452. next call of inflate().
  453. If the history buffer is provided by the application, next_out must
  454. never be changed by the application since the decompressor maintains
  455. history information inside this buffer from call to call; the application
  456. can only reset next_out to the beginning of the history buffer when
  457. avail_out is zero and all output has been consumed.
  458. inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
  459. not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
  460. windowBits < 8). msg is set to null if there is no error message.
  461. inflateInit2 does not perform any decompression: this will be done by
  462. inflate().
  463. */
  464. extern int inflateSync OF((z_stream *strm));
  465. /*
  466. Skips invalid compressed data until the special marker (see deflate()
  467. above) can be found, or until all available input is skipped. No output
  468. is provided.
  469. inflateSync returns Z_OK if the special marker has been found, Z_BUF_ERROR
  470. if no more input was provided, Z_DATA_ERROR if no marker has been found,
  471. or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
  472. case, the application may save the current current value of total_in which
  473. indicates where valid compressed data was found. In the error case, the
  474. application may repeatedly call inflateSync, providing more input each time,
  475. until success or end of the input data.
  476. */
  477. extern int inflateReset OF((z_stream *strm));
  478. /*
  479. This function is equivalent to inflateEnd followed by inflateInit,
  480. but does not free and reallocate all the internal decompression state.
  481. The stream will keep attributes that may have been set by inflateInit2.
  482. inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
  483. stream state was inconsistent (such as zalloc or state being NULL).
  484. */
  485. extern int inflateIncomp OF((z_stream *strm));
  486. /*
  487. This function adds the data at next_in (avail_in bytes) to the output
  488. history without performing any output. There must be no pending output,
  489. and the decompressor must be expecting to see the start of a block.
  490. Calling this function is equivalent to decompressing a stored block
  491. containing the data at next_in (except that the data is not output).
  492. */
  493. /* checksum functions */
  494. /*
  495. This function is not related to compression but is exported
  496. anyway because it might be useful in applications using the
  497. compression library.
  498. */
  499. extern uLong adler32 OF((uLong adler, Bytef *buf, uInt len));
  500. /*
  501. Update a running Adler-32 checksum with the bytes buf[0..len-1] and
  502. return the updated checksum. If buf is NULL, this function returns
  503. the required initial value for the checksum.
  504. An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
  505. much faster. Usage example:
  506. uLong adler = adler32(0L, Z_NULL, 0);
  507. while (read_buffer(buffer, length) != EOF) {
  508. adler = adler32(adler, buffer, length);
  509. }
  510. if (adler != original_adler) error();
  511. */
  512. #ifndef _Z_UTIL_H
  513. struct internal_state {int dummy;}; /* hack for buggy compilers */
  514. #endif
  515. #endif /* _ZLIB_H */