/jcl/source/common/zlib.h
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1/* zlib.h -- interface of the 'zlib' general purpose compression library 2 version 1.2.5, April 19th, 2010 3 4 Copyright (C) 1995-2010 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 http://www.ietf.org/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 "1.2.5" 41#define ZLIB_VERNUM 0x1250 42#define ZLIB_VER_MAJOR 1 43#define ZLIB_VER_MINOR 2 44#define ZLIB_VER_REVISION 5 45#define ZLIB_VER_SUBREVISION 0 46 47/* 48 The 'zlib' compression library provides in-memory compression and 49 decompression functions, including integrity checks of the uncompressed data. 50 This version of the library supports only one compression method (deflation) 51 but other algorithms will be added later and will have the same stream 52 interface. 53 54 Compression can be done in a single step if the buffers are large enough, 55 or can be done by repeated calls of the compression function. In the latter 56 case, the application must provide more input and/or consume the output 57 (providing more output space) before each call. 58 59 The compressed data format used by default by the in-memory functions is 60 the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped 61 around a deflate stream, which is itself documented in RFC 1951. 62 63 The library also supports reading and writing files in gzip (.gz) format 64 with an interface similar to that of stdio using the functions that start 65 with "gz". The gzip format is different from the zlib format. gzip is a 66 gzip wrapper, documented in RFC 1952, wrapped around a deflate stream. 67 68 This library can optionally read and write gzip streams in memory as well. 69 70 The zlib format was designed to be compact and fast for use in memory 71 and on communications channels. The gzip format was designed for single- 72 file compression on file systems, has a larger header than zlib to maintain 73 directory information, and uses a different, slower check method than zlib. 74 75 The library does not install any signal handler. The decoder checks 76 the consistency of the compressed data, so the library should never crash 77 even in case of corrupted input. 78*/ 79 80typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size)); 81typedef void (*free_func) OF((voidpf opaque, voidpf address)); 82 83struct internal_state; 84 85typedef struct z_stream_s { 86 Bytef *next_in; /* next input byte */ 87 uInt avail_in; /* number of bytes available at next_in */ 88 uLong total_in; /* total nb of input bytes read so far */ 89 90 Bytef *next_out; /* next output byte should be put there */ 91 uInt avail_out; /* remaining free space at next_out */ 92 uLong total_out; /* total nb of bytes output so far */ 93 94 char *msg; /* last error message, NULL if no error */ 95 struct internal_state FAR *state; /* not visible by applications */ 96 97 alloc_func zalloc; /* used to allocate the internal state */ 98 free_func zfree; /* used to free the internal state */ 99 voidpf opaque; /* private data object passed to zalloc and zfree */ 100 101 int data_type; /* best guess about the data type: binary or text */ 102 uLong adler; /* adler32 value of the uncompressed data */ 103 uLong reserved; /* reserved for future use */ 104} z_stream; 105 106typedef z_stream FAR *z_streamp; 107 108/* 109 gzip header information passed to and from zlib routines. See RFC 1952 110 for more details on the meanings of these fields. 111*/ 112typedef struct gz_header_s { 113 int text; /* true if compressed data believed to be text */ 114 uLong time; /* modification time */ 115 int xflags; /* extra flags (not used when writing a gzip file) */ 116 int os; /* operating system */ 117 Bytef *extra; /* pointer to extra field or Z_NULL if none */ 118 uInt extra_len; /* extra field length (valid if extra != Z_NULL) */ 119 uInt extra_max; /* space at extra (only when reading header) */ 120 Bytef *name; /* pointer to zero-terminated file name or Z_NULL */ 121 uInt name_max; /* space at name (only when reading header) */ 122 Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */ 123 uInt comm_max; /* space at comment (only when reading header) */ 124 int hcrc; /* true if there was or will be a header crc */ 125 int done; /* true when done reading gzip header (not used 126 when writing a gzip file) */ 127} gz_header; 128 129typedef gz_header FAR *gz_headerp; 130 131/* 132 The application must update next_in and avail_in when avail_in has dropped 133 to zero. It must update next_out and avail_out when avail_out has dropped 134 to zero. The application must initialize zalloc, zfree and opaque before 135 calling the init function. All other fields are set by the compression 136 library and must not be updated by the application. 137 138 The opaque value provided by the application will be passed as the first 139 parameter for calls of zalloc and zfree. This can be useful for custom 140 memory management. The compression library attaches no meaning to the 141 opaque value. 142 143 zalloc must return Z_NULL if there is not enough memory for the object. 144 If zlib is used in a multi-threaded application, zalloc and zfree must be 145 thread safe. 146 147 On 16-bit systems, the functions zalloc and zfree must be able to allocate 148 exactly 65536 bytes, but will not be required to allocate more than this if 149 the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers 150 returned by zalloc for objects of exactly 65536 bytes *must* have their 151 offset normalized to zero. The default allocation function provided by this 152 library ensures this (see zutil.c). To reduce memory requirements and avoid 153 any allocation of 64K objects, at the expense of compression ratio, compile 154 the library with -DMAX_WBITS=14 (see zconf.h). 155 156 The fields total_in and total_out can be used for statistics or progress 157 reports. After compression, total_in holds the total size of the 158 uncompressed data and may be saved for use in the decompressor (particularly 159 if the decompressor wants to decompress everything in a single step). 160*/ 161 162 /* constants */ 163 164#define Z_NO_FLUSH 0 165#define Z_PARTIAL_FLUSH 1 166#define Z_SYNC_FLUSH 2 167#define Z_FULL_FLUSH 3 168#define Z_FINISH 4 169#define Z_BLOCK 5 170#define Z_TREES 6 171/* Allowed flush values; see deflate() and inflate() below for details */ 172 173#define Z_OK 0 174#define Z_STREAM_END 1 175#define Z_NEED_DICT 2 176#define Z_ERRNO (-1) 177#define Z_STREAM_ERROR (-2) 178#define Z_DATA_ERROR (-3) 179#define Z_MEM_ERROR (-4) 180#define Z_BUF_ERROR (-5) 181#define Z_VERSION_ERROR (-6) 182/* Return codes for the compression/decompression functions. Negative values 183 * are errors, positive values are used for special but normal events. 184 */ 185 186#define Z_NO_COMPRESSION 0 187#define Z_BEST_SPEED 1 188#define Z_BEST_COMPRESSION 9 189#define Z_DEFAULT_COMPRESSION (-1) 190/* compression levels */ 191 192#define Z_FILTERED 1 193#define Z_HUFFMAN_ONLY 2 194#define Z_RLE 3 195#define Z_FIXED 4 196#define Z_DEFAULT_STRATEGY 0 197/* compression strategy; see deflateInit2() below for details */ 198 199#define Z_BINARY 0 200#define Z_TEXT 1 201#define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */ 202#define Z_UNKNOWN 2 203/* Possible values of the data_type field (though see inflate()) */ 204 205#define Z_DEFLATED 8 206/* The deflate compression method (the only one supported in this version) */ 207 208#define Z_NULL 0 /* for initializing zalloc, zfree, opaque */ 209 210#define zlib_version zlibVersion() 211/* for compatibility with versions < 1.0.2 */ 212 213 214 /* basic functions */ 215 216ZEXTERN const char * ZEXPORT zlibVersion OF((void)); 217/* The application can compare zlibVersion and ZLIB_VERSION for consistency. 218 If the first character differs, the library code actually used is not 219 compatible with the zlib.h header file used by the application. This check 220 is automatically made by deflateInit and inflateInit. 221 */ 222 223/* 224ZEXTERN int ZEXPORT deflateInit OF((z_streamp strm, int level)); 225 226 Initializes the internal stream state for compression. The fields 227 zalloc, zfree and opaque must be initialized before by the caller. If 228 zalloc and zfree are set to Z_NULL, deflateInit updates them to use default 229 allocation functions. 230 231 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9: 232 1 gives best speed, 9 gives best compression, 0 gives no compression at all 233 (the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION 234 requests a default compromise between speed and compression (currently 235 equivalent to level 6). 236 237 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough 238 memory, Z_STREAM_ERROR if level is not a valid compression level, or 239 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible 240 with the version assumed by the caller (ZLIB_VERSION). msg is set to null 241 if there is no error message. deflateInit does not perform any compression: 242 this will be done by deflate(). 243*/ 244 245 246ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush)); 247/* 248 deflate compresses as much data as possible, and stops when the input 249 buffer becomes empty or the output buffer becomes full. It may introduce 250 some output latency (reading input without producing any output) except when 251 forced to flush. 252 253 The detailed semantics are as follows. deflate performs one or both of the 254 following actions: 255 256 - Compress more input starting at next_in and update next_in and avail_in 257 accordingly. If not all input can be processed (because there is not 258 enough room in the output buffer), next_in and avail_in are updated and 259 processing will resume at this point for the next call of deflate(). 260 261 - Provide more output starting at next_out and update next_out and avail_out 262 accordingly. This action is forced if the parameter flush is non zero. 263 Forcing flush frequently degrades the compression ratio, so this parameter 264 should be set only when necessary (in interactive applications). Some 265 output may be provided even if flush is not set. 266 267 Before the call of deflate(), the application should ensure that at least 268 one of the actions is possible, by providing more input and/or consuming more 269 output, and updating avail_in or avail_out accordingly; avail_out should 270 never be zero before the call. The application can consume the compressed 271 output when it wants, for example when the output buffer is full (avail_out 272 == 0), or after each call of deflate(). If deflate returns Z_OK and with 273 zero avail_out, it must be called again after making room in the output 274 buffer because there might be more output pending. 275 276 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to 277 decide how much data to accumulate before producing output, in order to 278 maximize compression. 279 280 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is 281 flushed to the output buffer and the output is aligned on a byte boundary, so 282 that the decompressor can get all input data available so far. (In 283 particular avail_in is zero after the call if enough output space has been 284 provided before the call.) Flushing may degrade compression for some 285 compression algorithms and so it should be used only when necessary. This 286 completes the current deflate block and follows it with an empty stored block 287 that is three bits plus filler bits to the next byte, followed by four bytes 288 (00 00 ff ff). 289 290 If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the 291 output buffer, but the output is not aligned to a byte boundary. All of the 292 input data so far will be available to the decompressor, as for Z_SYNC_FLUSH. 293 This completes the current deflate block and follows it with an empty fixed 294 codes block that is 10 bits long. This assures that enough bytes are output 295 in order for the decompressor to finish the block before the empty fixed code 296 block. 297 298 If flush is set to Z_BLOCK, a deflate block is completed and emitted, as 299 for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to 300 seven bits of the current block are held to be written as the next byte after 301 the next deflate block is completed. In this case, the decompressor may not 302 be provided enough bits at this point in order to complete decompression of 303 the data provided so far to the compressor. It may need to wait for the next 304 block to be emitted. This is for advanced applications that need to control 305 the emission of deflate blocks. 306 307 If flush is set to Z_FULL_FLUSH, all output is flushed as with 308 Z_SYNC_FLUSH, and the compression state is reset so that decompression can 309 restart from this point if previous compressed data has been damaged or if 310 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade 311 compression. 312 313 If deflate returns with avail_out == 0, this function must be called again 314 with the same value of the flush parameter and more output space (updated 315 avail_out), until the flush is complete (deflate returns with non-zero 316 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that 317 avail_out is greater than six to avoid repeated flush markers due to 318 avail_out == 0 on return. 319 320 If the parameter flush is set to Z_FINISH, pending input is processed, 321 pending output is flushed and deflate returns with Z_STREAM_END if there was 322 enough output space; if deflate returns with Z_OK, this function must be 323 called again with Z_FINISH and more output space (updated avail_out) but no 324 more input data, until it returns with Z_STREAM_END or an error. After 325 deflate has returned Z_STREAM_END, the only possible operations on the stream 326 are deflateReset or deflateEnd. 327 328 Z_FINISH can be used immediately after deflateInit if all the compression 329 is to be done in a single step. In this case, avail_out must be at least the 330 value returned by deflateBound (see below). If deflate does not return 331 Z_STREAM_END, then it must be called again as described above. 332 333 deflate() sets strm->adler to the adler32 checksum of all input read 334 so far (that is, total_in bytes). 335 336 deflate() may update strm->data_type if it can make a good guess about 337 the input data type (Z_BINARY or Z_TEXT). In doubt, the data is considered 338 binary. This field is only for information purposes and does not affect the 339 compression algorithm in any manner. 340 341 deflate() returns Z_OK if some progress has been made (more input 342 processed or more output produced), Z_STREAM_END if all input has been 343 consumed and all output has been produced (only when flush is set to 344 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example 345 if next_in or next_out was Z_NULL), Z_BUF_ERROR if no progress is possible 346 (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not 347 fatal, and deflate() can be called again with more input and more output 348 space to continue compressing. 349*/ 350 351 352ZEXTERN int ZEXPORT deflateEnd OF((z_streamp strm)); 353/* 354 All dynamically allocated data structures for this stream are freed. 355 This function discards any unprocessed input and does not flush any pending 356 output. 357 358 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the 359 stream state was inconsistent, Z_DATA_ERROR if the stream was freed 360 prematurely (some input or output was discarded). In the error case, msg 361 may be set but then points to a static string (which must not be 362 deallocated). 363*/ 364 365 366/* 367ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm)); 368 369 Initializes the internal stream state for decompression. The fields 370 next_in, avail_in, zalloc, zfree and opaque must be initialized before by 371 the caller. If next_in is not Z_NULL and avail_in is large enough (the 372 exact value depends on the compression method), inflateInit determines the 373 compression method from the zlib header and allocates all data structures 374 accordingly; otherwise the allocation will be deferred to the first call of 375 inflate. If zalloc and zfree are set to Z_NULL, inflateInit updates them to 376 use default allocation functions. 377 378 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough 379 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the 380 version assumed by the caller, or Z_STREAM_ERROR if the parameters are 381 invalid, such as a null pointer to the structure. msg is set to null if 382 there is no error message. inflateInit does not perform any decompression 383 apart from possibly reading the zlib header if present: actual decompression 384 will be done by inflate(). (So next_in and avail_in may be modified, but 385 next_out and avail_out are unused and unchanged.) The current implementation 386 of inflateInit() does not process any header information -- that is deferred 387 until inflate() is called. 388*/ 389 390 391ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush)); 392/* 393 inflate decompresses as much data as possible, and stops when the input 394 buffer becomes empty or the output buffer becomes full. It may introduce 395 some output latency (reading input without producing any output) except when 396 forced to flush. 397 398 The detailed semantics are as follows. inflate performs one or both of the 399 following actions: 400 401 - Decompress more input starting at next_in and update next_in and avail_in 402 accordingly. If not all input can be processed (because there is not 403 enough room in the output buffer), next_in is updated and processing will 404 resume at this point for the next call of inflate(). 405 406 - Provide more output starting at next_out and update next_out and avail_out 407 accordingly. inflate() provides as much output as possible, until there is 408 no more input data or no more space in the output buffer (see below about 409 the flush parameter). 410 411 Before the call of inflate(), the application should ensure that at least 412 one of the actions is possible, by providing more input and/or consuming more 413 output, and updating the next_* and avail_* values accordingly. The 414 application can consume the uncompressed output when it wants, for example 415 when the output buffer is full (avail_out == 0), or after each call of 416 inflate(). If inflate returns Z_OK and with zero avail_out, it must be 417 called again after making room in the output buffer because there might be 418 more output pending. 419 420 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH, 421 Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much 422 output as possible to the output buffer. Z_BLOCK requests that inflate() 423 stop if and when it gets to the next deflate block boundary. When decoding 424 the zlib or gzip format, this will cause inflate() to return immediately 425 after the header and before the first block. When doing a raw inflate, 426 inflate() will go ahead and process the first block, and will return when it 427 gets to the end of that block, or when it runs out of data. 428 429 The Z_BLOCK option assists in appending to or combining deflate streams. 430 Also to assist in this, on return inflate() will set strm->data_type to the 431 number of unused bits in the last byte taken from strm->next_in, plus 64 if 432 inflate() is currently decoding the last block in the deflate stream, plus 433 128 if inflate() returned immediately after decoding an end-of-block code or 434 decoding the complete header up to just before the first byte of the deflate 435 stream. The end-of-block will not be indicated until all of the uncompressed 436 data from that block has been written to strm->next_out. The number of 437 unused bits may in general be greater than seven, except when bit 7 of 438 data_type is set, in which case the number of unused bits will be less than 439 eight. data_type is set as noted here every time inflate() returns for all 440 flush options, and so can be used to determine the amount of currently 441 consumed input in bits. 442 443 The Z_TREES option behaves as Z_BLOCK does, but it also returns when the 444 end of each deflate block header is reached, before any actual data in that 445 block is decoded. This allows the caller to determine the length of the 446 deflate block header for later use in random access within a deflate block. 447 256 is added to the value of strm->data_type when inflate() returns 448 immediately after reaching the end of the deflate block header. 449 450 inflate() should normally be called until it returns Z_STREAM_END or an 451 error. However if all decompression is to be performed in a single step (a 452 single call of inflate), the parameter flush should be set to Z_FINISH. In 453 this case all pending input is processed and all pending output is flushed; 454 avail_out must be large enough to hold all the uncompressed data. (The size 455 of the uncompressed data may have been saved by the compressor for this 456 purpose.) The next operation on this stream must be inflateEnd to deallocate 457 the decompression state. The use of Z_FINISH is never required, but can be 458 used to inform inflate that a faster approach may be used for the single 459 inflate() call. 460 461 In this implementation, inflate() always flushes as much output as 462 possible to the output buffer, and always uses the faster approach on the 463 first call. So the only effect of the flush parameter in this implementation 464 is on the return value of inflate(), as noted below, or when it returns early 465 because Z_BLOCK or Z_TREES is used. 466 467 If a preset dictionary is needed after this call (see inflateSetDictionary 468 below), inflate sets strm->adler to the adler32 checksum of the dictionary 469 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets 470 strm->adler to the adler32 checksum of all output produced so far (that is, 471 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described 472 below. At the end of the stream, inflate() checks that its computed adler32 473 checksum is equal to that saved by the compressor and returns Z_STREAM_END 474 only if the checksum is correct. 475 476 inflate() can decompress and check either zlib-wrapped or gzip-wrapped 477 deflate data. The header type is detected automatically, if requested when 478 initializing with inflateInit2(). Any information contained in the gzip 479 header is not retained, so applications that need that information should 480 instead use raw inflate, see inflateInit2() below, or inflateBack() and 481 perform their own processing of the gzip header and trailer. 482 483 inflate() returns Z_OK if some progress has been made (more input processed 484 or more output produced), Z_STREAM_END if the end of the compressed data has 485 been reached and all uncompressed output has been produced, Z_NEED_DICT if a 486 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was 487 corrupted (input stream not conforming to the zlib format or incorrect check 488 value), Z_STREAM_ERROR if the stream structure was inconsistent (for example 489 next_in or next_out was Z_NULL), Z_MEM_ERROR if there was not enough memory, 490 Z_BUF_ERROR if no progress is possible or if there was not enough room in the 491 output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and 492 inflate() can be called again with more input and more output space to 493 continue decompressing. If Z_DATA_ERROR is returned, the application may 494 then call inflateSync() to look for a good compression block if a partial 495 recovery of the data is desired. 496*/ 497 498 499ZEXTERN int ZEXPORT inflateEnd OF((z_streamp strm)); 500/* 501 All dynamically allocated data structures for this stream are freed. 502 This function discards any unprocessed input and does not flush any pending 503 output. 504 505 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state 506 was inconsistent. In the error case, msg may be set but then points to a 507 static string (which must not be deallocated). 508*/ 509 510 511 /* Advanced functions */ 512 513/* 514 The following functions are needed only in some special applications. 515*/ 516 517/* 518ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm, 519 int level, 520 int method, 521 int windowBits, 522 int memLevel, 523 int strategy)); 524 525 This is another version of deflateInit with more compression options. The 526 fields next_in, zalloc, zfree and opaque must be initialized before by the 527 caller. 528 529 The method parameter is the compression method. It must be Z_DEFLATED in 530 this version of the library. 531 532 The windowBits parameter is the base two logarithm of the window size 533 (the size of the history buffer). It should be in the range 8..15 for this 534 version of the library. Larger values of this parameter result in better 535 compression at the expense of memory usage. The default value is 15 if 536 deflateInit is used instead. 537 538 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits 539 determines the window size. deflate() will then generate raw deflate data 540 with no zlib header or trailer, and will not compute an adler32 check value. 541 542 windowBits can also be greater than 15 for optional gzip encoding. Add 543 16 to windowBits to write a simple gzip header and trailer around the 544 compressed data instead of a zlib wrapper. The gzip header will have no 545 file name, no extra data, no comment, no modification time (set to zero), no 546 header crc, and the operating system will be set to 255 (unknown). If a 547 gzip stream is being written, strm->adler is a crc32 instead of an adler32. 548 549 The memLevel parameter specifies how much memory should be allocated 550 for the internal compression state. memLevel=1 uses minimum memory but is 551 slow and reduces compression ratio; memLevel=9 uses maximum memory for 552 optimal speed. The default value is 8. See zconf.h for total memory usage 553 as a function of windowBits and memLevel. 554 555 The strategy parameter is used to tune the compression algorithm. Use the 556 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a 557 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no 558 string match), or Z_RLE to limit match distances to one (run-length 559 encoding). Filtered data consists mostly of small values with a somewhat 560 random distribution. In this case, the compression algorithm is tuned to 561 compress them better. The effect of Z_FILTERED is to force more Huffman 562 coding and less string matching; it is somewhat intermediate between 563 Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as 564 fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The 565 strategy parameter only affects the compression ratio but not the 566 correctness of the compressed output even if it is not set appropriately. 567 Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler 568 decoder for special applications. 569 570 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough 571 memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid 572 method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is 573 incompatible with the version assumed by the caller (ZLIB_VERSION). msg is 574 set to null if there is no error message. deflateInit2 does not perform any 575 compression: this will be done by deflate(). 576*/ 577 578ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm, 579 const Bytef *dictionary, 580 uInt dictLength)); 581/* 582 Initializes the compression dictionary from the given byte sequence 583 without producing any compressed output. This function must be called 584 immediately after deflateInit, deflateInit2 or deflateReset, before any call 585 of deflate. The compressor and decompressor must use exactly the same 586 dictionary (see inflateSetDictionary). 587 588 The dictionary should consist of strings (byte sequences) that are likely 589 to be encountered later in the data to be compressed, with the most commonly 590 used strings preferably put towards the end of the dictionary. Using a 591 dictionary is most useful when the data to be compressed is short and can be 592 predicted with good accuracy; the data can then be compressed better than 593 with the default empty dictionary. 594 595 Depending on the size of the compression data structures selected by 596 deflateInit or deflateInit2, a part of the dictionary may in effect be 597 discarded, for example if the dictionary is larger than the window size 598 provided in deflateInit or deflateInit2. Thus the strings most likely to be 599 useful should be put at the end of the dictionary, not at the front. In 600 addition, the current implementation of deflate will use at most the window 601 size minus 262 bytes of the provided dictionary. 602 603 Upon return of this function, strm->adler is set to the adler32 value 604 of the dictionary; the decompressor may later use this value to determine 605 which dictionary has been used by the compressor. (The adler32 value 606 applies to the whole dictionary even if only a subset of the dictionary is 607 actually used by the compressor.) If a raw deflate was requested, then the 608 adler32 value is not computed and strm->adler is not set. 609 610 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a 611 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is 612 inconsistent (for example if deflate has already been called for this stream 613 or if the compression method is bsort). deflateSetDictionary does not 614 perform any compression: this will be done by deflate(). 615*/ 616 617ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest, 618 z_streamp source)); 619/* 620 Sets the destination stream as a complete copy of the source stream. 621 622 This function can be useful when several compression strategies will be 623 tried, for example when there are several ways of pre-processing the input 624 data with a filter. The streams that will be discarded should then be freed 625 by calling deflateEnd. Note that deflateCopy duplicates the internal 626 compression state which can be quite large, so this strategy is slow and can 627 consume lots of memory. 628 629 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not 630 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent 631 (such as zalloc being Z_NULL). msg is left unchanged in both source and 632 destination. 633*/ 634 635ZEXTERN int ZEXPORT deflateReset OF((z_streamp strm)); 636/* 637 This function is equivalent to deflateEnd followed by deflateInit, 638 but does not free and reallocate all the internal compression state. The 639 stream will keep the same compression level and any other attributes that 640 may have been set by deflateInit2. 641 642 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source 643 stream state was inconsistent (such as zalloc or state being Z_NULL). 644*/ 645 646ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm, 647 int level, 648 int strategy)); 649/* 650 Dynamically update the compression level and compression strategy. The 651 interpretation of level and strategy is as in deflateInit2. This can be 652 used to switch between compression and straight copy of the input data, or 653 to switch to a different kind of input data requiring a different strategy. 654 If the compression level is changed, the input available so far is 655 compressed with the old level (and may be flushed); the new level will take 656 effect only at the next call of deflate(). 657 658 Before the call of deflateParams, the stream state must be set as for 659 a call of deflate(), since the currently available input may have to be 660 compressed and flushed. In particular, strm->avail_out must be non-zero. 661 662 deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source 663 stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR if 664 strm->avail_out was zero. 665*/ 666 667ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm, 668 int good_length, 669 int max_lazy, 670 int nice_length, 671 int max_chain)); 672/* 673 Fine tune deflate's internal compression parameters. This should only be 674 used by someone who understands the algorithm used by zlib's deflate for 675 searching for the best matching string, and even then only by the most 676 fanatic optimizer trying to squeeze out the last compressed bit for their 677 specific input data. Read the deflate.c source code for the meaning of the 678 max_lazy, good_length, nice_length, and max_chain parameters. 679 680 deflateTune() can be called after deflateInit() or deflateInit2(), and 681 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream. 682 */ 683 684ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm, 685 uLong sourceLen)); 686/* 687 deflateBound() returns an upper bound on the compressed size after 688 deflation of sourceLen bytes. It must be called after deflateInit() or 689 deflateInit2(), and after deflateSetHeader(), if used. This would be used 690 to allocate an output buffer for deflation in a single pass, and so would be 691 called before deflate(). 692*/ 693 694ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm, 695 int bits, 696 int value)); 697/* 698 deflatePrime() inserts bits in the deflate output stream. The intent 699 is that this function is used to start off the deflate output with the bits 700 leftover from a previous deflate stream when appending to it. As such, this 701 function can only be used for raw deflate, and must be used before the first 702 deflate() call after a deflateInit2() or deflateReset(). bits must be less 703 than or equal to 16, and that many of the least significant bits of value 704 will be inserted in the output. 705 706 deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source 707 stream state was inconsistent. 708*/ 709 710ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm, 711 gz_headerp head)); 712/* 713 deflateSetHeader() provides gzip header information for when a gzip 714 stream is requested by deflateInit2(). deflateSetHeader() may be called 715 after deflateInit2() or deflateReset() and before the first call of 716 deflate(). The text, time, os, extra field, name, and comment information 717 in the provided gz_header structure are written to the gzip header (xflag is 718 ignored -- the extra flags are set according to the compression level). The 719 caller must assure that, if not Z_NULL, name and comment are terminated with 720 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are 721 available there. If hcrc is true, a gzip header crc is included. Note that 722 the current versions of the command-line version of gzip (up through version 723 1.3.x) do not support header crc's, and will report that it is a "multi-part 724 gzip file" and give up. 725 726 If deflateSetHeader is not used, the default gzip header has text false, 727 the time set to zero, and os set to 255, with no extra, name, or comment 728 fields. The gzip header is returned to the default state by deflateReset(). 729 730 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source 731 stream state was inconsistent. 732*/ 733 734/* 735ZEXTERN int ZEXPORT inflateInit2 OF((z_streamp strm, 736 int windowBits)); 737 738 This is another version of inflateInit with an extra parameter. The 739 fields next_in, avail_in, zalloc, zfree and opaque must be initialized 740 before by the caller. 741 742 The windowBits parameter is the base two logarithm of the maximum window 743 size (the size of the history buffer). It should be in the range 8..15 for 744 this version of the library. The default value is 15 if inflateInit is used 745 instead. windowBits must be greater than or equal to the windowBits value 746 provided to deflateInit2() while compressing, or it must be equal to 15 if 747 deflateInit2() was not used. If a compressed stream with a larger window 748 size is given as input, inflate() will return with the error code 749 Z_DATA_ERROR instead of trying to allocate a larger window. 750 751 windowBits can also be zero to request that inflate use the window size in 752 the zlib header of the compressed stream. 753 754 windowBits can also be -8..-15 for raw inflate. In this case, -windowBits 755 determines the window size. inflate() will then process raw deflate data, 756 not looking for a zlib or gzip header, not generating a check value, and not 757 looking for any check values for comparison at the end of the stream. This 758 is for use with other formats that use the deflate compressed data format 759 such as zip. Those formats provide their own check values. If a custom 760 format is developed using the raw deflate format for compressed data, it is 761 recommended that a check value such as an adler32 or a crc32 be applied to 762 the uncompressed data as is done in the zlib, gzip, and zip formats. For 763 most applications, the zlib format should be used as is. Note that comments 764 above on the use in deflateInit2() applies to the magnitude of windowBits. 765 766 windowBits can also be greater than 15 for optional gzip decoding. Add 767 32 to windowBits to enable zlib and gzip decoding with automatic header 768 detection, or add 16 to decode only the gzip format (the zlib format will 769 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a 770 crc32 instead of an adler32. 771 772 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough 773 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the 774 version assumed by the caller, or Z_STREAM_ERROR if the parameters are 775 invalid, such as a null pointer to the structure. msg is set to null if 776 there is no error message. inflateInit2 does not perform any decompression 777 apart from possibly reading the zlib header if present: actual decompression 778 will be done by inflate(). (So next_in and avail_in may be modified, but 779 next_out and avail_out are unused and unchanged.) The current implementation 780 of inflateInit2() does not process any header information -- that is 781 deferred until inflate() is called. 782*/ 783 784ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm, 785 const Bytef *dictionary, 786 uInt dictLength)); 787/* 788 Initializes the decompression dictionary from the given uncompressed byte 789 sequence. This function must be called immediately after a call of inflate, 790 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor 791 can be determined from the adler32 value returned by that call of inflate. 792 The compressor and decompressor must use exactly the same dictionary (see 793 deflateSetDictionary). For raw inflate, this function can be called 794 immediately after inflateInit2() or inflateReset() and before any call of 795 inflate() to set the dictionary. The application must insure that the 796 dictionary that was used for compression is provided. 797 798 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a 799 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is 800 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the 801 expected one (incorrect adler32 value). inflateSetDictionary does not 802 perform any decompression: this will be done by subsequent calls of 803 inflate(). 804*/ 805 806ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm)); 807/* 808 Skips invalid compressed data until a full flush point (see above the 809 description of deflate with Z_FULL_FLUSH) can be found, or until all 810 available input is skipped. No output is provided. 811 812 inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR 813 if no more input was provided, Z_DATA_ERROR if no flush point has been 814 found, or Z_STREAM_ERROR if the stream structure was inconsistent. In the 815 success case, the application may save the current current value of total_in 816 which indicates where valid compressed data was found. In the error case, 817 the application may repeatedly call inflateSync, providing more input each 818 time, until success or end of the input data. 819*/ 820 821ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest, 822 z_streamp source)); 823/* 824 Sets the destination stream as a complete copy of the source stream. 825 826 This function can be useful when randomly accessing a large stream. The 827 first pass through the stream can periodically record the inflate state, 828 allowing restarting inflate at those points when randomly accessing the 829 stream. 830 831 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not 832 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent 833 (such as zalloc being Z_NULL). msg is left unchanged in both source and 834 destination. 835*/ 836 837ZEXTERN int ZEXPORT inflateReset OF((z_streamp strm)); 838/* 839 This function is equivalent to inflateEnd followed by inflateInit, 840 but does not free and reallocate all the internal decompression state. The 841 stream will keep attributes that may have been set by inflateInit2. 842 843 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source 844 stream state was inconsistent (such as zalloc or state being Z_NULL). 845*/ 846 847ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm, 848 int windowBits)); 849/* 850 This function is the same as inflateReset, but it also permits changing 851 the wrap and window size requests. The windowBits parameter is interpreted 852 the same as it is for inflateInit2. 853 854 inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source 855 stream state was inconsistent (such as zalloc or state being Z_NULL), or if 856 the windowBits parameter is invalid. 857*/ 858 859ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm, 860 int bits, 861 int value)); 862/* 863 This function inserts bits in the inflate input stream. The intent is 864 that this function is used to start inflating at a bit position in the 865 middle of a byte. The provided bits will be used before any bytes are used 866 from next_in. This function should only be used with raw inflate, and 867 should be used before the first inflate() call after inflateInit2() or 868 inflateReset(). bits must be less than or equal to 16, and that many of the 869 least significant bits of value will be inserted in the input. 870 871 If bits is negative, then the input stream bit buffer is emptied. Then 872 inflatePrime() can be called again to put bits in the buffer. This is used 873 to clear out bits leftover after feeding inflate a block description prior 874 to feeding inflate codes. 875 876 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source 877 stream state was inconsistent. 878*/ 879 880ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm)); 881/* 882 This function returns two values, one in the lower 16 bits of the return 883 value, and the other in the remaining upper bits, obtained by shifting the 884 return value down 16 bits. If the upper value is -1 and the lower value is 885 zero, then inflate() is currently decoding information outside of a block. 886 If the upper value is -1 and the lower value is non-zero, then inflate is in 887 the middle of a stored block, with the lower value equaling the number of 888 bytes from the input remaining to copy. If the upper value is not -1, then 889 it is the number of bits back from the current bit position in the input of 890 the code (literal or length/distance pair) currently being processed. In 891 that case the lower value is the number of bytes already emitted for that 892 code. 893 894 A code is being processed if inflate is waiting for more input to complete 895 decoding of the code, or if it has completed decoding but is waiting for 896 more output space to write the literal or match data. 897 898 inflateMark() is used to mark locations in the input data for random 899 access, which may be at bit positions, and to note those cases where the 900 output of a code may span boundaries of random access blocks. The current 901 location in the input stream can be determined from avail_in and data_type 902 as noted in the description for the Z_BLOCK flush parameter for inflate. 903 904 inflateMark returns the value noted above or -1 << 16 if the provided 905 source stream state was inconsistent. 906*/ 907 908ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm, 909 gz_headerp head)); 910/* 911 inflateGetHeader() requests that gzip header information be stored in the 912 provided gz_header structure. inflateGetHeader() may be called after 913 inflateInit2() or inflateReset(), and before the first call of inflate(). 914 As inflate() processes the gzip stream, head->done is zero until the header 915 is completed, at which time head->done is set to one. If a zlib stream is 916 being decoded, then head->done is set to -1 to indicate that there will be 917 no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be 918 used to force inflate() to return immediately after header processing is 919 complete and before any actual data is decompressed. 920 921 The text, time, xflags, and os fields are filled in with the gzip header 922 contents. hcrc is set to true if there is a header CRC. (The header CRC 923 was valid if done is set to one.) If extra is not Z_NULL, then extra_max 924 contains the maximum number of bytes to write to extra. Once done is true, 925 extra_len contains the actual extra field length, and extra contains the 926 extra field, or that field truncated if extra_max is less than extra_len. 927 If name is not Z_NULL, then up to name_max characters are written there, 928 terminated with a zero unless the length is greater than name_max. If 929 comment is not Z_NULL, then up to comm_max characters are written there, 930 terminated with a zero unless the length is greater than comm_max. When any 931 of extra, name, or comment are not Z_NULL and the respective field is not 932 present in the header, then that field is set to Z_NULL to signal its 933 absence. This allows the use of deflateSetHeader() with the returned 934 structure to duplicate the header. However if those fields are set to 935 allocated memory, then the application will need to save those pointers 936 elsewhere so that they can be eventually freed. 937 938 If inflateGetHeader is not used, then the header information is simply 939 discarded. The header is always checked for validity, including the header 940 CRC if present. inflateReset() will reset the process to discard the header 941 information. The application would need to call inflateGetHeader() again to 942 retrieve the header from the next gzip stream. 943 944 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source 945 stream state was inconsistent. 946*/ 947 948/* 949ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits, 950 unsigned char FAR *window)); 951 952 Initialize the internal stream state for decompression using inflateBack() 953 calls. The fields zalloc, zfree and opaque in strm must be initialized 954 before the call. If zalloc and zfree are Z_NULL, then the default library- 955 derived memory allocation routines are used. windowBits is the base two 956 logarithm of the window size, in the range 8..15. window is a caller 957 supplied buffer of that size. Except for special applications where it is 958 assured that deflate was used with small window sizes, windowBits must be 15 959 and a 32K byte window must be supplied to be able to decompress general 960 deflate streams. 961 962 See inflateBack() for the usage of these routines. 963 964 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of 965 the paramaters are invalid, Z_MEM_ERROR if the internal state could not be 966 allocated, or Z_VERSION_ERROR if the version of the library does not match 967 the version of the header file. 968*/ 969 970typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *)); 971typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned)); 972 973ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm, 974 …
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