1/* deflate.c -- compress data using the deflation algorithm 2 * Copyright (C) 1995-2024 Jean-loup Gailly and Mark Adler 3 * For conditions of distribution and use, see copyright notice in zlib.h 4 */ 5 6/* 7 * ALGORITHM 8 * 9 * The "deflation" process depends on being able to identify portions 10 * of the input text which are identical to earlier input (within a 11 * sliding window trailing behind the input currently being processed). 12 * 13 * The most straightforward technique turns out to be the fastest for 14 * most input files: try all possible matches and select the longest. 15 * The key feature of this algorithm is that insertions into the string 16 * dictionary are very simple and thus fast, and deletions are avoided 17 * completely. Insertions are performed at each input character, whereas 18 * string matches are performed only when the previous match ends. So it 19 * is preferable to spend more time in matches to allow very fast string 20 * insertions and avoid deletions. The matching algorithm for small 21 * strings is inspired from that of Rabin & Karp. A brute force approach 22 * is used to find longer strings when a small match has been found. 23 * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze 24 * (by Leonid Broukhis). 25 * A previous version of this file used a more sophisticated algorithm 26 * (by Fiala and Greene) which is guaranteed to run in linear amortized 27 * time, but has a larger average cost, uses more memory and is patented. 28 * However the F&G algorithm may be faster for some highly redundant 29 * files if the parameter max_chain_length (described below) is too large. 30 * 31 * ACKNOWLEDGEMENTS 32 * 33 * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and 34 * I found it in 'freeze' written by Leonid Broukhis. 35 * Thanks to many people for bug reports and testing. 36 * 37 * REFERENCES 38 * 39 * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification". 40 * Available in http://tools.ietf.org/html/rfc1951 41 * 42 * A description of the Rabin and Karp algorithm is given in the book 43 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252. 44 * 45 * Fiala,E.R., and Greene,D.H. 46 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595 47 * 48 */ 49 50/* @(#) $Id$ */ 51 52#include "deflate.h" 53 54const char deflate_copyright[] = 55 " deflate 1.3.1 Copyright 1995-2024 Jean-loup Gailly and Mark Adler "; 56/* 57 If you use the zlib library in a product, an acknowledgment is welcome 58 in the documentation of your product. If for some reason you cannot 59 include such an acknowledgment, I would appreciate that you keep this 60 copyright string in the executable of your product. 61 */ 62 63typedef enum { 64 need_more, /* block not completed, need more input or more output */ 65 block_done, /* block flush performed */ 66 finish_started, /* finish started, need only more output at next deflate */ 67 finish_done /* finish done, accept no more input or output */ 68} block_state; 69 70typedef block_state (*compress_func)(deflate_state *s, int flush); 71/* Compression function. Returns the block state after the call. */ 72 73local block_state deflate_stored(deflate_state *s, int flush); 74local block_state deflate_fast(deflate_state *s, int flush); 75#ifndef FASTEST 76local block_state deflate_slow(deflate_state *s, int flush); 77#endif 78local block_state deflate_rle(deflate_state *s, int flush); 79local block_state deflate_huff(deflate_state *s, int flush); 80 81/* =========================================================================== 82 * Local data 83 */ 84 85#define NIL 0 86/* Tail of hash chains */ 87 88#ifndef TOO_FAR 89# define TOO_FAR 4096 90#endif 91/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ 92 93/* Values for max_lazy_match, good_match and max_chain_length, depending on 94 * the desired pack level (0..9). The values given below have been tuned to 95 * exclude worst case performance for pathological files. Better values may be 96 * found for specific files. 97 */ 98typedef struct config_s { 99 ush good_length; /* reduce lazy search above this match length */ 100 ush max_lazy; /* do not perform lazy search above this match length */ 101 ush nice_length; /* quit search above this match length */ 102 ush max_chain; 103 compress_func func; 104} config; 105 106#ifdef FASTEST 107local const config configuration_table[2] = { 108/* good lazy nice chain */ 109/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 110/* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ 111#else 112local const config configuration_table[10] = { 113/* good lazy nice chain */ 114/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 115/* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ 116/* 2 */ {4, 5, 16, 8, deflate_fast}, 117/* 3 */ {4, 6, 32, 32, deflate_fast}, 118 119/* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ 120/* 5 */ {8, 16, 32, 32, deflate_slow}, 121/* 6 */ {8, 16, 128, 128, deflate_slow}, 122/* 7 */ {8, 32, 128, 256, deflate_slow}, 123/* 8 */ {32, 128, 258, 1024, deflate_slow}, 124/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ 125#endif 126 127/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 128 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different 129 * meaning. 130 */ 131 132/* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */ 133#define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0)) 134 135/* =========================================================================== 136 * Update a hash value with the given input byte 137 * IN assertion: all calls to UPDATE_HASH are made with consecutive input 138 * characters, so that a running hash key can be computed from the previous 139 * key instead of complete recalculation each time. 140 */ 141#define UPDATE_HASH(s,h,c) (h = (((h) << s->hash_shift) ^ (c)) & s->hash_mask) 142 143 144/* =========================================================================== 145 * Insert string str in the dictionary and set match_head to the previous head 146 * of the hash chain (the most recent string with same hash key). Return 147 * the previous length of the hash chain. 148 * If this file is compiled with -DFASTEST, the compression level is forced 149 * to 1, and no hash chains are maintained. 150 * IN assertion: all calls to INSERT_STRING are made with consecutive input 151 * characters and the first MIN_MATCH bytes of str are valid (except for 152 * the last MIN_MATCH-1 bytes of the input file). 153 */ 154#ifdef FASTEST 155#define INSERT_STRING(s, str, match_head) \ 156 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 157 match_head = s->head[s->ins_h], \ 158 s->head[s->ins_h] = (Pos)(str)) 159#else 160#define INSERT_STRING(s, str, match_head) \ 161 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 162 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ 163 s->head[s->ins_h] = (Pos)(str)) 164#endif 165 166/* =========================================================================== 167 * Initialize the hash table (avoiding 64K overflow for 16 bit systems). 168 * prev[] will be initialized on the fly. 169 */ 170#define CLEAR_HASH(s) \ 171 do { \ 172 s->head[s->hash_size - 1] = NIL; \ 173 zmemzero((Bytef *)s->head, \ 174 (unsigned)(s->hash_size - 1)*sizeof(*s->head)); \ 175 } while (0) 176 177/* =========================================================================== 178 * Slide the hash table when sliding the window down (could be avoided with 32 179 * bit values at the expense of memory usage). We slide even when level == 0 to 180 * keep the hash table consistent if we switch back to level > 0 later. 181 */ 182#if defined(__has_feature) 183# if __has_feature(memory_sanitizer) 184 __attribute__((no_sanitize("memory"))) 185# endif 186#endif 187local void slide_hash(deflate_state *s) 188{ 189 unsigned n, m; 190 Posf *p; 191 uInt wsize = s->w_size; 192 193 n = s->hash_size; 194 p = &s->head[n]; 195 do { 196 m = *--p; 197 *p = (Pos)(m >= wsize ? m - wsize : NIL); 198 } while (--n); 199 n = wsize; 200#ifndef FASTEST 201 p = &s->prev[n]; 202 do { 203 m = *--p; 204 *p = (Pos)(m >= wsize ? m - wsize : NIL); 205 /* If n is not on any hash chain, prev[n] is garbage but 206 * its value will never be used. 207 */ 208 } while (--n); 209#endif 210} 211 212/* =========================================================================== 213 * Read a new buffer from the current input stream, update the adler32 214 * and total number of bytes read. All deflate() input goes through 215 * this function so some applications may wish to modify it to avoid 216 * allocating a large strm->next_in buffer and copying from it. 217 * (See also flush_pending()). 218 */ 219local unsigned read_buf(z_streamp strm, Bytef *buf, unsigned size) 220{ 221 unsigned len = strm->avail_in; 222 223 if (len > size) len = size; 224 if (len == 0) return 0; 225 226 strm->avail_in -= len; 227 228 zmemcpy(buf, strm->next_in, len); 229 if (strm->state->wrap == 1) { 230 strm->adler = adler32(strm->adler, buf, len); 231 } 232#ifdef GZIP 233 else if (strm->state->wrap == 2) { 234 strm->adler = crc32(strm->adler, buf, len); 235 } 236#endif 237 strm->next_in += len; 238 strm->total_in += len; 239 240 return len; 241} 242 243/* =========================================================================== 244 * Fill the window when the lookahead becomes insufficient. 245 * Updates strstart and lookahead. 246 * 247 * IN assertion: lookahead < MIN_LOOKAHEAD 248 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 249 * At least one byte has been read, or avail_in == 0; reads are 250 * performed for at least two bytes (required for the zip translate_eol 251 * option -- not supported here). 252 */ 253local void fill_window(deflate_state *s) 254{ 255 unsigned n; 256 unsigned more; /* Amount of free space at the end of the window. */ 257 uInt wsize = s->w_size; 258 259 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); 260 261 do { 262 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 263 264 /* Deal with !@#$% 64K limit: */ 265 if (sizeof(int) <= 2) { 266 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 267 more = wsize; 268 269 } else if (more == (unsigned)(-1)) { 270 /* Very unlikely, but possible on 16 bit machine if 271 * strstart == 0 && lookahead == 1 (input done a byte at time) 272 */ 273 more--; 274 } 275 } 276 277 /* If the window is almost full and there is insufficient lookahead, 278 * move the upper half to the lower one to make room in the upper half. 279 */ 280 if (s->strstart >= wsize + MAX_DIST(s)) { 281 282 zmemcpy(s->window, s->window + wsize, (unsigned)wsize - more); 283 s->match_start -= wsize; 284 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 285 s->block_start -= (long) wsize; 286 if (s->insert > s->strstart) 287 s->insert = s->strstart; 288 slide_hash(s); 289 more += wsize; 290 } 291 if (s->strm->avail_in == 0) break; 292 293 /* If there was no sliding: 294 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 295 * more == window_size - lookahead - strstart 296 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 297 * => more >= window_size - 2*WSIZE + 2 298 * In the BIG_MEM or MMAP case (not yet supported), 299 * window_size == input_size + MIN_LOOKAHEAD && 300 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 301 * Otherwise, window_size == 2*WSIZE so more >= 2. 302 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 303 */ 304 Assert(more >= 2, "more < 2"); 305 306 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 307 s->lookahead += n; 308 309 /* Initialize the hash value now that we have some input: */ 310 if (s->lookahead + s->insert >= MIN_MATCH) { 311 uInt str = s->strstart - s->insert; 312 s->ins_h = s->window[str]; 313 UPDATE_HASH(s, s->ins_h, s->window[str + 1]); 314#if MIN_MATCH != 3 315 Call UPDATE_HASH() MIN_MATCH-3 more times 316#endif 317 while (s->insert) { 318 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 319#ifndef FASTEST 320 s->prev[str & s->w_mask] = s->head[s->ins_h]; 321#endif 322 s->head[s->ins_h] = (Pos)str; 323 str++; 324 s->insert--; 325 if (s->lookahead + s->insert < MIN_MATCH) 326 break; 327 } 328 } 329 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 330 * but this is not important since only literal bytes will be emitted. 331 */ 332 333 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 334 335 /* If the WIN_INIT bytes after the end of the current data have never been 336 * written, then zero those bytes in order to avoid memory check reports of 337 * the use of uninitialized (or uninitialised as Julian writes) bytes by 338 * the longest match routines. Update the high water mark for the next 339 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 340 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 341 */ 342 if (s->high_water < s->window_size) { 343 ulg curr = s->strstart + (ulg)(s->lookahead); 344 ulg init; 345 346 if (s->high_water < curr) { 347 /* Previous high water mark below current data -- zero WIN_INIT 348 * bytes or up to end of window, whichever is less. 349 */ 350 init = s->window_size - curr; 351 if (init > WIN_INIT) 352 init = WIN_INIT; 353 zmemzero(s->window + curr, (unsigned)init); 354 s->high_water = curr + init; 355 } 356 else if (s->high_water < (ulg)curr + WIN_INIT) { 357 /* High water mark at or above current data, but below current data 358 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 359 * to end of window, whichever is less. 360 */ 361 init = (ulg)curr + WIN_INIT - s->high_water; 362 if (init > s->window_size - s->high_water) 363 init = s->window_size - s->high_water; 364 zmemzero(s->window + s->high_water, (unsigned)init); 365 s->high_water += init; 366 } 367 } 368 369 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 370 "not enough room for search"); 371} 372 373/* ========================================================================= */ 374int ZEXPORT deflateInit_(z_streamp strm, int level, const char *version, 375 int stream_size) { 376 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, 377 Z_DEFAULT_STRATEGY, version, stream_size); 378 /* To do: ignore strm->next_in if we use it as window */ 379} 380 381/* ========================================================================= */ 382int ZEXPORT deflateInit2_(z_streamp strm, int level, int method, 383 int windowBits, int memLevel, int strategy, 384 const char *version, int stream_size) { 385 deflate_state *s; 386 int wrap = 1; 387 static const char my_version[] = ZLIB_VERSION; 388 389 if (version == Z_NULL || version[0] != my_version[0] || 390 stream_size != sizeof(z_stream)) { 391 return Z_VERSION_ERROR; 392 } 393 if (strm == Z_NULL) return Z_STREAM_ERROR; 394 395 strm->msg = Z_NULL; 396 if (strm->zalloc == (alloc_func)0) { 397#ifdef Z_SOLO 398 return Z_STREAM_ERROR; 399#else 400 strm->zalloc = zcalloc; 401 strm->opaque = (voidpf)0; 402#endif 403 } 404 if (strm->zfree == (free_func)0) 405#ifdef Z_SOLO 406 return Z_STREAM_ERROR; 407#else 408 strm->zfree = zcfree; 409#endif 410 411#ifdef FASTEST 412 if (level != 0) level = 1; 413#else 414 if (level == Z_DEFAULT_COMPRESSION) level = 6; 415#endif 416 417 if (windowBits < 0) { /* suppress zlib wrapper */ 418 wrap = 0; 419 if (windowBits < -15) 420 return Z_STREAM_ERROR; 421 windowBits = -windowBits; 422 } 423#ifdef GZIP 424 else if (windowBits > 15) { 425 wrap = 2; /* write gzip wrapper instead */ 426 windowBits -= 16; 427 } 428#endif 429 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 430 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 431 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) { 432 return Z_STREAM_ERROR; 433 } 434 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 435 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 436 if (s == Z_NULL) return Z_MEM_ERROR; 437 strm->state = (struct internal_state FAR *)s; 438 s->strm = strm; 439 s->status = INIT_STATE; /* to pass state test in deflateReset() */ 440 441 s->wrap = wrap; 442 s->gzhead = Z_NULL; 443 s->w_bits = (uInt)windowBits; 444 s->w_size = 1 << s->w_bits; 445 s->w_mask = s->w_size - 1; 446 447 s->hash_bits = (uInt)memLevel + 7; 448 s->hash_size = 1 << s->hash_bits; 449 s->hash_mask = s->hash_size - 1; 450 s->hash_shift = ((s->hash_bits + MIN_MATCH-1) / MIN_MATCH); 451 452 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 453 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 454 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 455 456 s->high_water = 0; /* nothing written to s->window yet */ 457 458 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 459 460 /* We overlay pending_buf and sym_buf. This works since the average size 461 * for length/distance pairs over any compressed block is assured to be 31 462 * bits or less. 463 * 464 * Analysis: The longest fixed codes are a length code of 8 bits plus 5 465 * extra bits, for lengths 131 to 257. The longest fixed distance codes are 466 * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest 467 * possible fixed-codes length/distance pair is then 31 bits total. 468 * 469 * sym_buf starts one-fourth of the way into pending_buf. So there are 470 * three bytes in sym_buf for every four bytes in pending_buf. Each symbol 471 * in sym_buf is three bytes -- two for the distance and one for the 472 * literal/length. As each symbol is consumed, the pointer to the next 473 * sym_buf value to read moves forward three bytes. From that symbol, up to 474 * 31 bits are written to pending_buf. The closest the written pending_buf 475 * bits gets to the next sym_buf symbol to read is just before the last 476 * code is written. At that time, 31*(n - 2) bits have been written, just 477 * after 24*(n - 2) bits have been consumed from sym_buf. sym_buf starts at 478 * 8*n bits into pending_buf. (Note that the symbol buffer fills when n - 1 479 * symbols are written.) The closest the writing gets to what is unread is 480 * then n + 14 bits. Here n is lit_bufsize, which is 16384 by default, and 481 * can range from 128 to 32768. 482 * 483 * Therefore, at a minimum, there are 142 bits of space between what is 484 * written and what is read in the overlain buffers, so the symbols cannot 485 * be overwritten by the compressed data. That space is actually 139 bits, 486 * due to the three-bit fixed-code block header. 487 * 488 * That covers the case where either Z_FIXED is specified, forcing fixed 489 * codes, or when the use of fixed codes is chosen, because that choice 490 * results in a smaller compressed block than dynamic codes. That latter 491 * condition then assures that the above analysis also covers all dynamic 492 * blocks. A dynamic-code block will only be chosen to be emitted if it has 493 * fewer bits than a fixed-code block would for the same set of symbols. 494 * Therefore its average symbol length is assured to be less than 31. So 495 * the compressed data for a dynamic block also cannot overwrite the 496 * symbols from which it is being constructed. 497 */ 498 499 s->pending_buf = (uchf *) ZALLOC(strm, s->lit_bufsize, LIT_BUFS); 500 s->pending_buf_size = (ulg)s->lit_bufsize * 4; 501 502 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 503 s->pending_buf == Z_NULL) { 504 s->status = FINISH_STATE; 505 strm->msg = ERR_MSG(Z_MEM_ERROR); 506 deflateEnd (strm); 507 return Z_MEM_ERROR; 508 } 509#ifdef LIT_MEM 510 s->d_buf = (ushf *)(s->pending_buf + (s->lit_bufsize << 1)); 511 s->l_buf = s->pending_buf + (s->lit_bufsize << 2); 512 s->sym_end = s->lit_bufsize - 1; 513#else 514 s->sym_buf = s->pending_buf + s->lit_bufsize; 515 s->sym_end = (s->lit_bufsize - 1) * 3; 516#endif 517 /* We avoid equality with lit_bufsize*3 because of wraparound at 64K 518 * on 16 bit machines and because stored blocks are restricted to 519 * 64K-1 bytes. 520 */ 521 522 s->level = level; 523 s->strategy = strategy; 524 s->method = (Byte)method; 525 526 return deflateReset(strm); 527} 528 529/* ========================================================================= 530 * Check for a valid deflate stream state. Return 0 if ok, 1 if not. 531 */ 532local int deflateStateCheck(z_streamp strm) 533{ 534 deflate_state *s; 535 if (strm == Z_NULL || 536 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) 537 return 1; 538 s = strm->state; 539 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE && 540#ifdef GZIP 541 s->status != GZIP_STATE && 542#endif 543 s->status != EXTRA_STATE && 544 s->status != NAME_STATE && 545 s->status != COMMENT_STATE && 546 s->status != HCRC_STATE && 547 s->status != BUSY_STATE && 548 s->status != FINISH_STATE)) 549 return 1; 550 return 0; 551} 552 553/* ========================================================================= */ 554int ZEXPORT deflateSetDictionary(z_streamp strm, const Bytef *dictionary, 555 uInt dictLength) { 556 deflate_state *s; 557 uInt str, n; 558 int wrap; 559 unsigned avail; 560 z_const unsigned char *next; 561 562 if (deflateStateCheck(strm) || dictionary == Z_NULL) 563 return Z_STREAM_ERROR; 564 s = strm->state; 565 wrap = s->wrap; 566 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) 567 return Z_STREAM_ERROR; 568 569 /* when using zlib wrappers, compute Adler-32 for provided dictionary */ 570 if (wrap == 1) 571 strm->adler = adler32(strm->adler, dictionary, dictLength); 572 s->wrap = 0; /* avoid computing Adler-32 in read_buf */ 573 574 /* if dictionary would fill window, just replace the history */ 575 if (dictLength >= s->w_size) { 576 if (wrap == 0) { /* already empty otherwise */ 577 CLEAR_HASH(s); 578 s->strstart = 0; 579 s->block_start = 0L; 580 s->insert = 0; 581 } 582 dictionary += dictLength - s->w_size; /* use the tail */ 583 dictLength = s->w_size; 584 } 585 586 /* insert dictionary into window and hash */ 587 avail = strm->avail_in; 588 next = strm->next_in; 589 strm->avail_in = dictLength; 590 strm->next_in = (z_const Bytef *)dictionary; 591 fill_window(s); 592 while (s->lookahead >= MIN_MATCH) { 593 str = s->strstart; 594 n = s->lookahead - (MIN_MATCH-1); 595 do { 596 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 597#ifndef FASTEST 598 s->prev[str & s->w_mask] = s->head[s->ins_h]; 599#endif 600 s->head[s->ins_h] = (Pos)str; 601 str++; 602 } while (--n); 603 s->strstart = str; 604 s->lookahead = MIN_MATCH-1; 605 fill_window(s); 606 } 607 s->strstart += s->lookahead; 608 s->block_start = (long)s->strstart; 609 s->insert = s->lookahead; 610 s->lookahead = 0; 611 s->match_length = s->prev_length = MIN_MATCH-1; 612 s->match_available = 0; 613 strm->next_in = next; 614 strm->avail_in = avail; 615 s->wrap = wrap; 616 return Z_OK; 617} 618 619/* ========================================================================= */ 620int ZEXPORT deflateGetDictionary(z_streamp strm, Bytef *dictionary, 621 uInt *dictLength) { 622 deflate_state *s; 623 uInt len; 624 625 if (deflateStateCheck(strm)) 626 return Z_STREAM_ERROR; 627 s = strm->state; 628 len = s->strstart + s->lookahead; 629 if (len > s->w_size) 630 len = s->w_size; 631 if (dictionary != Z_NULL && len) 632 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len); 633 if (dictLength != Z_NULL) 634 *dictLength = len; 635 return Z_OK; 636} 637 638/* ========================================================================= */ 639int ZEXPORT deflateResetKeep(z_streamp strm) { 640 deflate_state *s; 641 642 if (deflateStateCheck(strm)) { 643 return Z_STREAM_ERROR; 644 } 645 646 strm->total_in = strm->total_out = 0; 647 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 648 strm->data_type = Z_UNKNOWN; 649 650 s = (deflate_state *)strm->state; 651 s->pending = 0; 652 s->pending_out = s->pending_buf; 653 654 if (s->wrap < 0) { 655 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 656 } 657 s->status = 658#ifdef GZIP 659 s->wrap == 2 ? GZIP_STATE : 660#endif 661 INIT_STATE; 662 strm->adler = 663#ifdef GZIP 664 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 665#endif 666 adler32(0L, Z_NULL, 0); 667 s->last_flush = -2; 668 669 _tr_init(s); 670 671 return Z_OK; 672} 673 674/* =========================================================================== 675 * Initialize the "longest match" routines for a new zlib stream 676 */ 677local void lm_init(deflate_state *s) 678{ 679 s->window_size = (ulg)2L*s->w_size; 680 681 CLEAR_HASH(s); 682 683 /* Set the default configuration parameters: 684 */ 685 s->max_lazy_match = configuration_table[s->level].max_lazy; 686 s->good_match = configuration_table[s->level].good_length; 687 s->nice_match = configuration_table[s->level].nice_length; 688 s->max_chain_length = configuration_table[s->level].max_chain; 689 690 s->strstart = 0; 691 s->block_start = 0L; 692 s->lookahead = 0; 693 s->insert = 0; 694 s->match_length = s->prev_length = MIN_MATCH-1; 695 s->match_available = 0; 696 s->ins_h = 0; 697} 698 699/* ========================================================================= */ 700int ZEXPORT deflateReset(z_streamp strm) { 701 int ret; 702 703 ret = deflateResetKeep(strm); 704 if (ret == Z_OK) 705 lm_init(strm->state); 706 return ret; 707} 708 709/* ========================================================================= */ 710int ZEXPORT deflateSetHeader(z_streamp strm, gz_headerp head) { 711 if (deflateStateCheck(strm) || strm->state->wrap != 2) 712 return Z_STREAM_ERROR; 713 strm->state->gzhead = head; 714 return Z_OK; 715} 716 717/* ========================================================================= */ 718int ZEXPORT deflatePending(z_streamp strm, unsigned *pending, int *bits) { 719 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 720 if (pending != Z_NULL) 721 *pending = strm->state->pending; 722 if (bits != Z_NULL) 723 *bits = strm->state->bi_valid; 724 return Z_OK; 725} 726 727/* ========================================================================= */ 728int ZEXPORT deflatePrime(z_streamp strm, int bits, int value) { 729 deflate_state *s; 730 int put; 731 732 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 733 s = strm->state; 734#ifdef LIT_MEM 735 if (bits < 0 || bits > 16 || 736 (uchf *)s->d_buf < s->pending_out + ((Buf_size + 7) >> 3)) 737 return Z_BUF_ERROR; 738#else 739 if (bits < 0 || bits > 16 || 740 s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3)) 741 return Z_BUF_ERROR; 742#endif 743 do { 744 put = Buf_size - s->bi_valid; 745 if (put > bits) 746 put = bits; 747 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); 748 s->bi_valid += put; 749 _tr_flush_bits(s); 750 value >>= put; 751 bits -= put; 752 } while (bits); 753 return Z_OK; 754} 755 756/* ========================================================================= */ 757int ZEXPORT deflateParams(z_streamp strm, int level, int strategy) { 758 deflate_state *s; 759 compress_func func; 760 761 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 762 s = strm->state; 763 764#ifdef FASTEST 765 if (level != 0) level = 1; 766#else 767 if (level == Z_DEFAULT_COMPRESSION) level = 6; 768#endif 769 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 770 return Z_STREAM_ERROR; 771 } 772 func = configuration_table[s->level].func; 773 774 if ((strategy != s->strategy || func != configuration_table[level].func) && 775 s->last_flush != -2) { 776 /* Flush the last buffer: */ 777 int err = deflate(strm, Z_BLOCK); 778 if (err == Z_STREAM_ERROR) 779 return err; 780 if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead) 781 return Z_BUF_ERROR; 782 } 783 if (s->level != level) { 784 if (s->level == 0 && s->matches != 0) { 785 if (s->matches == 1) 786 slide_hash(s); 787 else 788 CLEAR_HASH(s); 789 s->matches = 0; 790 } 791 s->level = level; 792 s->max_lazy_match = configuration_table[level].max_lazy; 793 s->good_match = configuration_table[level].good_length; 794 s->nice_match = configuration_table[level].nice_length; 795 s->max_chain_length = configuration_table[level].max_chain; 796 } 797 s->strategy = strategy; 798 return Z_OK; 799} 800 801/* ========================================================================= */ 802int ZEXPORT deflateTune(z_streamp strm, int good_length, int max_lazy, 803 int nice_length, int max_chain) { 804 deflate_state *s; 805 806 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 807 s = strm->state; 808 s->good_match = (uInt)good_length; 809 s->max_lazy_match = (uInt)max_lazy; 810 s->nice_match = nice_length; 811 s->max_chain_length = (uInt)max_chain; 812 return Z_OK; 813} 814 815/* ========================================================================= 816 * For the default windowBits of 15 and memLevel of 8, this function returns a 817 * close to exact, as well as small, upper bound on the compressed size. This 818 * is an expansion of ~0.03%, plus a small constant. 819 * 820 * For any setting other than those defaults for windowBits and memLevel, one 821 * of two worst case bounds is returned. This is at most an expansion of ~4% or 822 * ~13%, plus a small constant. 823 * 824 * Both the 0.03% and 4% derive from the overhead of stored blocks. The first 825 * one is for stored blocks of 16383 bytes (memLevel == 8), whereas the second 826 * is for stored blocks of 127 bytes (the worst case memLevel == 1). The 827 * expansion results from five bytes of header for each stored block. 828 * 829 * The larger expansion of 13% results from a window size less than or equal to 830 * the symbols buffer size (windowBits <= memLevel + 7). In that case some of 831 * the data being compressed may have slid out of the sliding window, impeding 832 * a stored block from being emitted. Then the only choice is a fixed or 833 * dynamic block, where a fixed block limits the maximum expansion to 9 bits 834 * per 8-bit byte, plus 10 bits for every block. The smallest block size for 835 * which this can occur is 255 (memLevel == 2). 836 * 837 * Shifts are used to approximate divisions, for speed. 838 */ 839uLong ZEXPORT deflateBound(z_streamp strm, uLong sourceLen) 840{ 841 deflate_state *s; 842 uLong fixedlen, storelen, wraplen; 843 844 /* upper bound for fixed blocks with 9-bit literals and length 255 845 (memLevel == 2, which is the lowest that may not use stored blocks) -- 846 ~13% overhead plus a small constant */ 847 fixedlen = sourceLen + (sourceLen >> 3) + (sourceLen >> 8) + 848 (sourceLen >> 9) + 4; 849 850 /* upper bound for stored blocks with length 127 (memLevel == 1) -- 851 ~4% overhead plus a small constant */ 852 storelen = sourceLen + (sourceLen >> 5) + (sourceLen >> 7) + 853 (sourceLen >> 11) + 7; 854 855 /* if can't get parameters, return larger bound plus a zlib wrapper */ 856 if (deflateStateCheck(strm)) 857 return (fixedlen > storelen ? fixedlen : storelen) + 6; 858 859 /* compute wrapper length */ 860 s = strm->state; 861 switch (s->wrap) { 862 case 0: /* raw deflate */ 863 wraplen = 0; 864 break; 865 case 1: /* zlib wrapper */ 866 wraplen = 6 + (s->strstart ? 4 : 0); 867 break; 868#ifdef GZIP 869 case 2: /* gzip wrapper */ 870 wraplen = 18; 871 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 872 Bytef *str; 873 if (s->gzhead->extra != Z_NULL) 874 wraplen += 2 + s->gzhead->extra_len; 875 str = s->gzhead->name; 876 if (str != Z_NULL) 877 do { 878 wraplen++; 879 } while (*str++); 880 str = s->gzhead->comment; 881 if (str != Z_NULL) 882 do { 883 wraplen++; 884 } while (*str++); 885 if (s->gzhead->hcrc) 886 wraplen += 2; 887 } 888 break; 889#endif 890 default: /* for compiler happiness */ 891 wraplen = 6; 892 } 893 894 /* if not default parameters, return one of the conservative bounds */ 895 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 896 return (s->w_bits <= s->hash_bits && s->level ? fixedlen : storelen) + 897 wraplen; 898 899 /* default settings: return tight bound for that case -- ~0.03% overhead 900 plus a small constant */ 901 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 902 (sourceLen >> 25) + 13 - 6 + wraplen; 903} 904 905/* ========================================================================= 906 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 907 * IN assertion: the stream state is correct and there is enough room in 908 * pending_buf. 909 */ 910local void putShortMSB(deflate_state *s, uInt b) 911{ 912 put_byte(s, (Byte)(b >> 8)); 913 put_byte(s, (Byte)(b & 0xff)); 914} 915 916/* ========================================================================= 917 * Flush as much pending output as possible. All deflate() output, except for 918 * some deflate_stored() output, goes through this function so some 919 * applications may wish to modify it to avoid allocating a large 920 * strm->next_out buffer and copying into it. (See also read_buf()). 921 */ 922local void flush_pending(z_streamp strm) 923{ 924 unsigned len; 925 deflate_state *s = strm->state; 926 927 _tr_flush_bits(s); 928 len = s->pending; 929 if (len > strm->avail_out) len = strm->avail_out; 930 if (len == 0) return; 931 932 zmemcpy(strm->next_out, s->pending_out, len); 933 strm->next_out += len; 934 s->pending_out += len; 935 strm->total_out += len; 936 strm->avail_out -= len; 937 s->pending -= len; 938 if (s->pending == 0) { 939 s->pending_out = s->pending_buf; 940 } 941} 942 943/* =========================================================================== 944 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1]. 945 */ 946#define HCRC_UPDATE(beg) \ 947 do { \ 948 if (s->gzhead->hcrc && s->pending > (beg)) \ 949 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \ 950 s->pending - (beg)); \ 951 } while (0) 952 953/* ========================================================================= */ 954int ZEXPORT deflate(z_streamp strm, int flush) { 955 int old_flush; /* value of flush param for previous deflate call */ 956 deflate_state *s; 957 958 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { 959 return Z_STREAM_ERROR; 960 } 961 s = strm->state; 962 963 if (strm->next_out == Z_NULL || 964 (strm->avail_in != 0 && strm->next_in == Z_NULL) || 965 (s->status == FINISH_STATE && flush != Z_FINISH)) { 966 ERR_RETURN(strm, Z_STREAM_ERROR); 967 } 968 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 969 970 old_flush = s->last_flush; 971 s->last_flush = flush; 972 973 /* Flush as much pending output as possible */ 974 if (s->pending != 0) { 975 flush_pending(strm); 976 if (strm->avail_out == 0) { 977 /* Since avail_out is 0, deflate will be called again with 978 * more output space, but possibly with both pending and 979 * avail_in equal to zero. There won't be anything to do, 980 * but this is not an error situation so make sure we 981 * return OK instead of BUF_ERROR at next call of deflate: 982 */ 983 s->last_flush = -1; 984 return Z_OK; 985 } 986 987 /* Make sure there is something to do and avoid duplicate consecutive 988 * flushes. For repeated and useless calls with Z_FINISH, we keep 989 * returning Z_STREAM_END instead of Z_BUF_ERROR. 990 */ 991 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 992 flush != Z_FINISH) { 993 ERR_RETURN(strm, Z_BUF_ERROR); 994 } 995 996 /* User must not provide more input after the first FINISH: */ 997 if (s->status == FINISH_STATE && strm->avail_in != 0) { 998 ERR_RETURN(strm, Z_BUF_ERROR); 999 } 1000 1001 /* Write the header */ 1002 if (s->status == INIT_STATE && s->wrap == 0) 1003 s->status = BUSY_STATE; 1004 if (s->status == INIT_STATE) { 1005 /* zlib header */ 1006 uInt header = (Z_DEFLATED + ((s->w_bits - 8) << 4)) << 8; 1007 uInt level_flags; 1008 1009 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 1010 level_flags = 0; 1011 else if (s->level < 6) 1012 level_flags = 1; 1013 else if (s->level == 6) 1014 level_flags = 2; 1015 else 1016 level_flags = 3; 1017 header |= (level_flags << 6); 1018 if (s->strstart != 0) header |= PRESET_DICT; 1019 header += 31 - (header % 31); 1020 1021 putShortMSB(s, header); 1022 1023 /* Save the adler32 of the preset dictionary: */ 1024 if (s->strstart != 0) { 1025 putShortMSB(s, (uInt)(strm->adler >> 16)); 1026 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1027 } 1028 strm->adler = adler32(0L, Z_NULL, 0); 1029 s->status = BUSY_STATE; 1030 1031 /* Compression must start with an empty pending buffer */ 1032 flush_pending(strm); 1033 if (s->pending != 0) { 1034 s->last_flush = -1; 1035 return Z_OK; 1036 } 1037 } 1038#ifdef GZIP 1039 if (s->status == GZIP_STATE) { 1040 /* gzip header */ 1041 strm->adler = crc32(0L, Z_NULL, 0); 1042 put_byte(s, 31); 1043 put_byte(s, 139); 1044 put_byte(s, 8); 1045 if (s->gzhead == Z_NULL) { 1046 put_byte(s, 0); 1047 put_byte(s, 0); 1048 put_byte(s, 0); 1049 put_byte(s, 0); 1050 put_byte(s, 0); 1051 put_byte(s, s->level == 9 ? 2 : 1052 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 1053 4 : 0)); 1054 put_byte(s, OS_CODE); 1055 s->status = BUSY_STATE; 1056 1057 /* Compression must start with an empty pending buffer */ 1058 flush_pending(strm); 1059 if (s->pending != 0) { 1060 s->last_flush = -1; 1061 return Z_OK; 1062 } 1063 } 1064 else { 1065 put_byte(s, (s->gzhead->text ? 1 : 0) + 1066 (s->gzhead->hcrc ? 2 : 0) + 1067 (s->gzhead->extra == Z_NULL ? 0 : 4) + 1068 (s->gzhead->name == Z_NULL ? 0 : 8) + 1069 (s->gzhead->comment == Z_NULL ? 0 : 16) 1070 ); 1071 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 1072 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 1073 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 1074 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 1075 put_byte(s, s->level == 9 ? 2 : 1076 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 1077 4 : 0)); 1078 put_byte(s, s->gzhead->os & 0xff); 1079 if (s->gzhead->extra != Z_NULL) { 1080 put_byte(s, s->gzhead->extra_len & 0xff); 1081 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 1082 } 1083 if (s->gzhead->hcrc) 1084 strm->adler = crc32(strm->adler, s->pending_buf, 1085 s->pending); 1086 s->gzindex = 0; 1087 s->status = EXTRA_STATE; 1088 } 1089 } 1090 if (s->status == EXTRA_STATE) { 1091 if (s->gzhead->extra != Z_NULL) { 1092 ulg beg = s->pending; /* start of bytes to update crc */ 1093 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex; 1094 while (s->pending + left > s->pending_buf_size) { 1095 uInt copy = s->pending_buf_size - s->pending; 1096 zmemcpy(s->pending_buf + s->pending, 1097 s->gzhead->extra + s->gzindex, copy); 1098 s->pending = s->pending_buf_size; 1099 HCRC_UPDATE(beg); 1100 s->gzindex += copy; 1101 flush_pending(strm); 1102 if (s->pending != 0) { 1103 s->last_flush = -1; 1104 return Z_OK; 1105 } 1106 beg = 0; 1107 left -= copy; 1108 } 1109 zmemcpy(s->pending_buf + s->pending, 1110 s->gzhead->extra + s->gzindex, left); 1111 s->pending += left; 1112 HCRC_UPDATE(beg); 1113 s->gzindex = 0; 1114 } 1115 s->status = NAME_STATE; 1116 } 1117 if (s->status == NAME_STATE) { 1118 if (s->gzhead->name != Z_NULL) { 1119 ulg beg = s->pending; /* start of bytes to update crc */ 1120 int val; 1121 do { 1122 if (s->pending == s->pending_buf_size) { 1123 HCRC_UPDATE(beg); 1124 flush_pending(strm); 1125 if (s->pending != 0) { 1126 s->last_flush = -1; 1127 return Z_OK; 1128 } 1129 beg = 0; 1130 } 1131 val = s->gzhead->name[s->gzindex++]; 1132 put_byte(s, val); 1133 } while (val != 0); 1134 HCRC_UPDATE(beg); 1135 s->gzindex = 0; 1136 } 1137 s->status = COMMENT_STATE; 1138 } 1139 if (s->status == COMMENT_STATE) { 1140 if (s->gzhead->comment != Z_NULL) { 1141 ulg beg = s->pending; /* start of bytes to update crc */ 1142 int val; 1143 do { 1144 if (s->pending == s->pending_buf_size) { 1145 HCRC_UPDATE(beg); 1146 flush_pending(strm); 1147 if (s->pending != 0) { 1148 s->last_flush = -1; 1149 return Z_OK; 1150 } 1151 beg = 0; 1152 } 1153 val = s->gzhead->comment[s->gzindex++]; 1154 put_byte(s, val); 1155 } while (val != 0); 1156 HCRC_UPDATE(beg); 1157 } 1158 s->status = HCRC_STATE; 1159 } 1160 if (s->status == HCRC_STATE) { 1161 if (s->gzhead->hcrc) { 1162 if (s->pending + 2 > s->pending_buf_size) { 1163 flush_pending(strm); 1164 if (s->pending != 0) { 1165 s->last_flush = -1; 1166 return Z_OK; 1167 } 1168 } 1169 put_byte(s, (Byte)(strm->adler & 0xff)); 1170 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1171 strm->adler = crc32(0L, Z_NULL, 0); 1172 } 1173 s->status = BUSY_STATE; 1174 1175 /* Compression must start with an empty pending buffer */ 1176 flush_pending(strm); 1177 if (s->pending != 0) { 1178 s->last_flush = -1; 1179 return Z_OK; 1180 } 1181 } 1182#endif 1183 1184 /* Start a new block or continue the current one. 1185 */ 1186 if (strm->avail_in != 0 || s->lookahead != 0 || 1187 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 1188 block_state bstate; 1189 1190 bstate = s->level == 0 ? deflate_stored(s, flush) : 1191 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 1192 s->strategy == Z_RLE ? deflate_rle(s, flush) : 1193 (*(configuration_table[s->level].func))(s, flush); 1194 1195 if (bstate == finish_started || bstate == finish_done) { 1196 s->status = FINISH_STATE; 1197 } 1198 if (bstate == need_more || bstate == finish_started) { 1199 if (strm->avail_out == 0) { 1200 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 1201 } 1202 return Z_OK; 1203 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 1204 * of deflate should use the same flush parameter to make sure 1205 * that the flush is complete. So we don't have to output an 1206 * empty block here, this will be done at next call. This also 1207 * ensures that for a very small output buffer, we emit at most 1208 * one empty block. 1209 */ 1210 } 1211 if (bstate == block_done) { 1212 if (flush == Z_PARTIAL_FLUSH) { 1213 _tr_align(s); 1214 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 1215 _tr_stored_block(s, (char*)0, 0L, 0); 1216 /* For a full flush, this empty block will be recognized 1217 * as a special marker by inflate_sync(). 1218 */ 1219 if (flush == Z_FULL_FLUSH) { 1220 CLEAR_HASH(s); /* forget history */ 1221 if (s->lookahead == 0) { 1222 s->strstart = 0; 1223 s->block_start = 0L; 1224 s->insert = 0; 1225 } 1226 } 1227 } 1228 flush_pending(strm); 1229 if (strm->avail_out == 0) { 1230 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 1231 return Z_OK; 1232 } 1233 } 1234 } 1235 1236 if (flush != Z_FINISH) return Z_OK; 1237 if (s->wrap <= 0) return Z_STREAM_END; 1238 1239 /* Write the trailer */ 1240#ifdef GZIP 1241 if (s->wrap == 2) { 1242 put_byte(s, (Byte)(strm->adler & 0xff)); 1243 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1244 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 1245 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 1246 put_byte(s, (Byte)(strm->total_in & 0xff)); 1247 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 1248 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 1249 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 1250 } 1251 else 1252#endif 1253 { 1254 putShortMSB(s, (uInt)(strm->adler >> 16)); 1255 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1256 } 1257 flush_pending(strm); 1258 /* If avail_out is zero, the application will call deflate again 1259 * to flush the rest. 1260 */ 1261 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 1262 return s->pending != 0 ? Z_OK : Z_STREAM_END; 1263} 1264 1265/* ========================================================================= */ 1266int ZEXPORT deflateEnd(z_streamp strm) { 1267 int status; 1268 1269 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 1270 1271 status = strm->state->status; 1272 1273 /* Deallocate in reverse order of allocations: */ 1274 TRY_FREE(strm, strm->state->pending_buf); 1275 TRY_FREE(strm, strm->state->head); 1276 TRY_FREE(strm, strm->state->prev); 1277 TRY_FREE(strm, strm->state->window); 1278 1279 ZFREE(strm, strm->state); 1280 strm->state = Z_NULL; 1281 1282 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1283} 1284 1285/* ========================================================================= 1286 * Copy the source state to the destination state. 1287 * To simplify the source, this is not supported for 16-bit MSDOS (which 1288 * doesn't have enough memory anyway to duplicate compression states). 1289 */ 1290int ZEXPORT deflateCopy(z_streamp dest, z_streamp source) { 1291#ifdef MAXSEG_64K 1292 (void)dest; 1293 (void)source; 1294 return Z_STREAM_ERROR; 1295#else 1296 deflate_state *ds; 1297 deflate_state *ss; 1298 1299 1300 if (deflateStateCheck(source) || dest == Z_NULL) { 1301 return Z_STREAM_ERROR; 1302 } 1303 1304 ss = source->state; 1305 1306 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream)); 1307 1308 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1309 if (ds == Z_NULL) return Z_MEM_ERROR; 1310 dest->state = (struct internal_state FAR *) ds; 1311 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state)); 1312 ds->strm = dest; 1313 1314 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1315 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1316 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1317 ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, LIT_BUFS); 1318 1319 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1320 ds->pending_buf == Z_NULL) { 1321 deflateEnd (dest); 1322 return Z_MEM_ERROR; 1323 } 1324 /* following zmemcpy do not work for 16-bit MSDOS */ 1325 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1326 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos)); 1327 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos)); 1328 zmemcpy(ds->pending_buf, ss->pending_buf, ds->lit_bufsize * LIT_BUFS); 1329 1330 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1331#ifdef LIT_MEM 1332 ds->d_buf = (ushf *)(ds->pending_buf + (ds->lit_bufsize << 1)); 1333 ds->l_buf = ds->pending_buf + (ds->lit_bufsize << 2); 1334#else 1335 ds->sym_buf = ds->pending_buf + ds->lit_bufsize; 1336#endif 1337 1338 ds->l_desc.dyn_tree = ds->dyn_ltree; 1339 ds->d_desc.dyn_tree = ds->dyn_dtree; 1340 ds->bl_desc.dyn_tree = ds->bl_tree; 1341 1342 return Z_OK; 1343#endif /* MAXSEG_64K */ 1344} 1345 1346#ifndef FASTEST 1347/* =========================================================================== 1348 * Set match_start to the longest match starting at the given string and 1349 * return its length. Matches shorter or equal to prev_length are discarded, 1350 * in which case the result is equal to prev_length and match_start is 1351 * garbage. 1352 * IN assertions: cur_match is the head of the hash chain for the current 1353 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1354 * OUT assertion: the match length is not greater than s->lookahead. 1355 */ 1356local uInt longest_match(deflate_state *s, IPos cur_match) 1357{ 1358 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1359 register Bytef *scan = s->window + s->strstart; /* current string */ 1360 register Bytef *match; /* matched string */ 1361 register int len; /* length of current match */ 1362 int best_len = (int)s->prev_length; /* best match length so far */ 1363 int nice_match = s->nice_match; /* stop if match long enough */ 1364 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1365 s->strstart - (IPos)MAX_DIST(s) : NIL; 1366 /* Stop when cur_match becomes <= limit. To simplify the code, 1367 * we prevent matches with the string of window index 0. 1368 */ 1369 Posf *prev = s->prev; 1370 uInt wmask = s->w_mask; 1371 1372#ifdef UNALIGNED_OK 1373 /* Compare two bytes at a time. Note: this is not always beneficial. 1374 * Try with and without -DUNALIGNED_OK to check. 1375 */ 1376 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1377 register ush scan_start = *(ushf*)scan; 1378 register ush scan_end = *(ushf*)(scan + best_len - 1); 1379#else 1380 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1381 register Byte scan_end1 = scan[best_len - 1]; 1382 register Byte scan_end = scan[best_len]; 1383#endif 1384 1385 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1386 * It is easy to get rid of this optimization if necessary. 1387 */ 1388 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1389 1390 /* Do not waste too much time if we already have a good match: */ 1391 if (s->prev_length >= s->good_match) { 1392 chain_length >>= 2; 1393 } 1394 /* Do not look for matches beyond the end of the input. This is necessary 1395 * to make deflate deterministic. 1396 */ 1397 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead; 1398 1399 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1400 "need lookahead"); 1401 1402 do { 1403 Assert(cur_match < s->strstart, "no future"); 1404 match = s->window + cur_match; 1405 1406 /* Skip to next match if the match length cannot increase 1407 * or if the match length is less than 2. Note that the checks below 1408 * for insufficient lookahead only occur occasionally for performance 1409 * reasons. Therefore uninitialized memory will be accessed, and 1410 * conditional jumps will be made that depend on those values. 1411 * However the length of the match is limited to the lookahead, so 1412 * the output of deflate is not affected by the uninitialized values. 1413 */ 1414#if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1415 /* This code assumes sizeof(unsigned short) == 2. Do not use 1416 * UNALIGNED_OK if your compiler uses a different size. 1417 */ 1418 if (*(ushf*)(match + best_len - 1) != scan_end || 1419 *(ushf*)match != scan_start) continue; 1420 1421 /* It is not necessary to compare scan[2] and match[2] since they are 1422 * always equal when the other bytes match, given that the hash keys 1423 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1424 * strstart + 3, + 5, up to strstart + 257. We check for insufficient 1425 * lookahead only every 4th comparison; the 128th check will be made 1426 * at strstart + 257. If MAX_MATCH-2 is not a multiple of 8, it is 1427 * necessary to put more guard bytes at the end of the window, or 1428 * to check more often for insufficient lookahead. 1429 */ 1430 Assert(scan[2] == match[2], "scan[2]?"); 1431 scan++, match++; 1432 do { 1433 } while (*(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1434 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1435 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1436 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1437 scan < strend); 1438 /* The funny "do {}" generates better code on most compilers */ 1439 1440 /* Here, scan <= window + strstart + 257 */ 1441 Assert(scan <= s->window + (unsigned)(s->window_size - 1), 1442 "wild scan"); 1443 if (*scan == *match) scan++; 1444 1445 len = (MAX_MATCH - 1) - (int)(strend - scan); 1446 scan = strend - (MAX_MATCH-1); 1447 1448#else /* UNALIGNED_OK */ 1449 1450 if (match[best_len] != scan_end || 1451 match[best_len - 1] != scan_end1 || 1452 *match != *scan || 1453 *++match != scan[1]) continue; 1454 1455 /* The check at best_len - 1 can be removed because it will be made 1456 * again later. (This heuristic is not always a win.) 1457 * It is not necessary to compare scan[2] and match[2] since they 1458 * are always equal when the other bytes match, given that 1459 * the hash keys are equal and that HASH_BITS >= 8. 1460 */ 1461 scan += 2, match++; 1462 Assert(*scan == *match, "match[2]?"); 1463 1464 /* We check for insufficient lookahead only every 8th comparison; 1465 * the 256th check will be made at strstart + 258. 1466 */ 1467 do { 1468 } while (*++scan == *++match && *++scan == *++match && 1469 *++scan == *++match && *++scan == *++match && 1470 *++scan == *++match && *++scan == *++match && 1471 *++scan == *++match && *++scan == *++match && 1472 scan < strend); 1473 1474 Assert(scan <= s->window + (unsigned)(s->window_size - 1), 1475 "wild scan"); 1476 1477 len = MAX_MATCH - (int)(strend - scan); 1478 scan = strend - MAX_MATCH; 1479 1480#endif /* UNALIGNED_OK */ 1481 1482 if (len > best_len) { 1483 s->match_start = cur_match; 1484 best_len = len; 1485 if (len >= nice_match) break; 1486#ifdef UNALIGNED_OK 1487 scan_end = *(ushf*)(scan + best_len - 1); 1488#else 1489 scan_end1 = scan[best_len - 1]; 1490 scan_end = scan[best_len]; 1491#endif 1492 } 1493 } while ((cur_match = prev[cur_match & wmask]) > limit 1494 && --chain_length != 0); 1495 1496 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1497 return s->lookahead; 1498} 1499 1500#else /* FASTEST */ 1501 1502/* --------------------------------------------------------------------------- 1503 * Optimized version for FASTEST only 1504 */ 1505local uInt longest_match(deflate_state *s, IPos cur_match) 1506{ 1507 register Bytef *scan = s->window + s->strstart; /* current string */ 1508 register Bytef *match; /* matched string */ 1509 register int len; /* length of current match */ 1510 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1511 1512 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1513 * It is easy to get rid of this optimization if necessary. 1514 */ 1515 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1516 1517 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1518 "need lookahead"); 1519 1520 Assert(cur_match < s->strstart, "no future"); 1521 1522 match = s->window + cur_match; 1523 1524 /* Return failure if the match length is less than 2: 1525 */ 1526 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1527 1528 /* The check at best_len - 1 can be removed because it will be made 1529 * again later. (This heuristic is not always a win.) 1530 * It is not necessary to compare scan[2] and match[2] since they 1531 * are always equal when the other bytes match, given that 1532 * the hash keys are equal and that HASH_BITS >= 8. 1533 */ 1534 scan += 2, match += 2; 1535 Assert(*scan == *match, "match[2]?"); 1536 1537 /* We check for insufficient lookahead only every 8th comparison; 1538 * the 256th check will be made at strstart + 258. 1539 */ 1540 do { 1541 } while (*++scan == *++match && *++scan == *++match && 1542 *++scan == *++match && *++scan == *++match && 1543 *++scan == *++match && *++scan == *++match && 1544 *++scan == *++match && *++scan == *++match && 1545 scan < strend); 1546 1547 Assert(scan <= s->window + (unsigned)(s->window_size - 1), "wild scan"); 1548 1549 len = MAX_MATCH - (int)(strend - scan); 1550 1551 if (len < MIN_MATCH) return MIN_MATCH - 1; 1552 1553 s->match_start = cur_match; 1554 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1555} 1556 1557#endif /* FASTEST */ 1558 1559#ifdef ZLIB_DEBUG 1560 1561#define EQUAL 0 1562/* result of memcmp for equal strings */ 1563 1564/* =========================================================================== 1565 * Check that the match at match_start is indeed a match. 1566 */ 1567local void check_match(deflate_state *s, IPos start, IPos match, int length) 1568{ 1569 /* check that the match is indeed a match */ 1570 Bytef *back = s->window + (int)match, *here = s->window + start; 1571 IPos len = length; 1572 if (match == (IPos)-1) { 1573 /* match starts one byte before the current window -- just compare the 1574 subsequent length-1 bytes */ 1575 back++; 1576 here++; 1577 len--; 1578 } 1579 if (zmemcmp(back, here, len) != EQUAL) { 1580 fprintf(stderr, " start %u, match %d, length %d\n", 1581 start, (int)match, length); 1582 do { 1583 fprintf(stderr, "(%02x %02x)", *back++, *here++); 1584 } while (--len != 0); 1585 z_error("invalid match"); 1586 } 1587 if (z_verbose > 1) { 1588 fprintf(stderr,"\\[%d,%d]", start - match, length); 1589 do { putc(s->window[start++], stderr); } while (--length != 0); 1590 } 1591} 1592#else 1593# define check_match(s, start, match, length) 1594#endif /* ZLIB_DEBUG */ 1595 1596/* =========================================================================== 1597 * Flush the current block, with given end-of-file flag. 1598 * IN assertion: strstart is set to the end of the current match. 1599 */ 1600#define FLUSH_BLOCK_ONLY(s, last) { \ 1601 _tr_flush_block(s, (s->block_start >= 0L ? \ 1602 (charf *)&s->window[(unsigned)s->block_start] : \ 1603 (charf *)Z_NULL), \ 1604 (ulg)((long)s->strstart - s->block_start), \ 1605 (last)); \ 1606 s->block_start = s->strstart; \ 1607 flush_pending(s->strm); \ 1608 Tracev((stderr,"[FLUSH]")); \ 1609} 1610 1611/* Same but force premature exit if necessary. */ 1612#define FLUSH_BLOCK(s, last) { \ 1613 FLUSH_BLOCK_ONLY(s, last); \ 1614 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1615} 1616 1617/* Maximum stored block length in deflate format (not including header). */ 1618#define MAX_STORED 65535 1619 1620/* Minimum of a and b. */ 1621#define MIN(a, b) ((a) > (b) ? (b) : (a)) 1622 1623/* =========================================================================== 1624 * Copy without compression as much as possible from the input stream, return 1625 * the current block state. 1626 * 1627 * In case deflateParams() is used to later switch to a non-zero compression 1628 * level, s->matches (otherwise unused when storing) keeps track of the number 1629 * of hash table slides to perform. If s->matches is 1, then one hash table 1630 * slide will be done when switching. If s->matches is 2, the maximum value 1631 * allowed here, then the hash table will be cleared, since two or more slides 1632 * is the same as a clear. 1633 * 1634 * deflate_stored() is written to minimize the number of times an input byte is 1635 * copied. It is most efficient with large input and output buffers, which 1636 * maximizes the opportunities to have a single copy from next_in to next_out. 1637 */ 1638local block_state deflate_stored(deflate_state *s, int flush) 1639{ 1640 /* Smallest worthy block size when not flushing or finishing. By default 1641 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For 1642 * large input and output buffers, the stored block size will be larger. 1643 */ 1644 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size); 1645 1646 /* Copy as many min_block or larger stored blocks directly to next_out as 1647 * possible. If flushing, copy the remaining available input to next_out as 1648 * stored blocks, if there is enough space. 1649 */ 1650 unsigned len, left, have, last = 0; 1651 unsigned used = s->strm->avail_in; 1652 do { 1653 /* Set len to the maximum size block that we can copy directly with the 1654 * available input data and output space. Set left to how much of that 1655 * would be copied from what's left in the window. 1656 */ 1657 len = MAX_STORED; /* maximum deflate stored block length */ 1658 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1659 if (s->strm->avail_out < have) /* need room for header */ 1660 break; 1661 /* maximum stored block length that will fit in avail_out: */ 1662 have = s->strm->avail_out - have; 1663 left = s->strstart - s->block_start; /* bytes left in window */ 1664 if (len > (ulg)left + s->strm->avail_in) 1665 len = left + s->strm->avail_in; /* limit len to the input */ 1666 if (len > have) 1667 len = have; /* limit len to the output */ 1668 1669 /* If the stored block would be less than min_block in length, or if 1670 * unable to copy all of the available input when flushing, then try 1671 * copying to the window and the pending buffer instead. Also don't 1672 * write an empty block when flushing -- deflate() does that. 1673 */ 1674 if (len < min_block && ((len == 0 && flush != Z_FINISH) || 1675 flush == Z_NO_FLUSH || 1676 len != left + s->strm->avail_in)) 1677 break; 1678 1679 /* Make a dummy stored block in pending to get the header bytes, 1680 * including any pending bits. This also updates the debugging counts. 1681 */ 1682 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0; 1683 _tr_stored_block(s, (char *)0, 0L, last); 1684 1685 /* Replace the lengths in the dummy stored block with len. */ 1686 s->pending_buf[s->pending - 4] = len; 1687 s->pending_buf[s->pending - 3] = len >> 8; 1688 s->pending_buf[s->pending - 2] = ~len; 1689 s->pending_buf[s->pending - 1] = ~len >> 8; 1690 1691 /* Write the stored block header bytes. */ 1692 flush_pending(s->strm); 1693 1694#ifdef ZLIB_DEBUG 1695 /* Update debugging counts for the data about to be copied. */ 1696 s->compressed_len += len << 3; 1697 s->bits_sent += len << 3; 1698#endif 1699 1700 /* Copy uncompressed bytes from the window to next_out. */ 1701 if (left) { 1702 if (left > len) 1703 left = len; 1704 zmemcpy(s->strm->next_out, s->window + s->block_start, left); 1705 s->strm->next_out += left; 1706 s->strm->avail_out -= left; 1707 s->strm->total_out += left; 1708 s->block_start += left; 1709 len -= left; 1710 } 1711 1712 /* Copy uncompressed bytes directly from next_in to next_out, updating 1713 * the check value. 1714 */ 1715 if (len) { 1716 read_buf(s->strm, s->strm->next_out, len); 1717 s->strm->next_out += len; 1718 s->strm->avail_out -= len; 1719 s->strm->total_out += len; 1720 } 1721 } while (last == 0); 1722 1723 /* Update the sliding window with the last s->w_size bytes of the copied 1724 * data, or append all of the copied data to the existing window if less 1725 * than s->w_size bytes were copied. Also update the number of bytes to 1726 * insert in the hash tables, in the event that deflateParams() switches to 1727 * a non-zero compression level. 1728 */ 1729 used -= s->strm->avail_in; /* number of input bytes directly copied */ 1730 if (used) { 1731 /* If any input was used, then no unused input remains in the window, 1732 * therefore s->block_start == s->strstart. 1733 */ 1734 if (used >= s->w_size) { /* supplant the previous history */ 1735 s->matches = 2; /* clear hash */ 1736 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size); 1737 s->strstart = s->w_size; 1738 s->insert = s->strstart; 1739 } 1740 else { 1741 if (s->window_size - s->strstart <= used) { 1742 /* Slide the window down. */ 1743 s->strstart -= s->w_size; 1744 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1745 if (s->matches < 2) 1746 s->matches++; /* add a pending slide_hash() */ 1747 if (s->insert > s->strstart) 1748 s->insert = s->strstart; 1749 } 1750 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used); 1751 s->strstart += used; 1752 s->insert += MIN(used, s->w_size - s->insert); 1753 } 1754 s->block_start = s->strstart; 1755 } 1756 if (s->high_water < s->strstart) 1757 s->high_water = s->strstart; 1758 1759 /* If the last block was written to next_out, then done. */ 1760 if (last) 1761 return finish_done; 1762 1763 /* If flushing and all input has been consumed, then done. */ 1764 if (flush != Z_NO_FLUSH && flush != Z_FINISH && 1765 s->strm->avail_in == 0 && (long)s->strstart == s->block_start) 1766 return block_done; 1767 1768 /* Fill the window with any remaining input. */ 1769 have = s->window_size - s->strstart; 1770 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) { 1771 /* Slide the window down. */ 1772 s->block_start -= s->w_size; 1773 s->strstart -= s->w_size; 1774 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1775 if (s->matches < 2) 1776 s->matches++; /* add a pending slide_hash() */ 1777 have += s->w_size; /* more space now */ 1778 if (s->insert > s->strstart) 1779 s->insert = s->strstart; 1780 } 1781 if (have > s->strm->avail_in) 1782 have = s->strm->avail_in; 1783 if (have) { 1784 read_buf(s->strm, s->window + s->strstart, have); 1785 s->strstart += have; 1786 s->insert += MIN(have, s->w_size - s->insert); 1787 } 1788 if (s->high_water < s->strstart) 1789 s->high_water = s->strstart; 1790 1791 /* There was not enough avail_out to write a complete worthy or flushed 1792 * stored block to next_out. Write a stored block to pending instead, if we 1793 * have enough input for a worthy block, or if flushing and there is enough 1794 * room for the remaining input as a stored block in the pending buffer. 1795 */ 1796 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1797 /* maximum stored block length that will fit in pending: */ 1798 have = MIN(s->pending_buf_size - have, MAX_STORED); 1799 min_block = MIN(have, s->w_size); 1800 left = s->strstart - s->block_start; 1801 if (left >= min_block || 1802 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH && 1803 s->strm->avail_in == 0 && left <= have)) { 1804 len = MIN(left, have); 1805 last = flush == Z_FINISH && s->strm->avail_in == 0 && 1806 len == left ? 1 : 0; 1807 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last); 1808 s->block_start += len; 1809 flush_pending(s->strm); 1810 } 1811 1812 /* We've done all we can with the available input and output. */ 1813 return last ? finish_started : need_more; 1814} 1815 1816/* =========================================================================== 1817 * Compress as much as possible from the input stream, return the current 1818 * block state. 1819 * This function does not perform lazy evaluation of matches and inserts 1820 * new strings in the dictionary only for unmatched strings or for short 1821 * matches. It is used only for the fast compression options. 1822 */ 1823local block_state deflate_fast(deflate_state *s, int flush) 1824{ 1825 IPos hash_head; /* head of the hash chain */ 1826 int bflush; /* set if current block must be flushed */ 1827 1828 for (;;) { 1829 /* Make sure that we always have enough lookahead, except 1830 * at the end of the input file. We need MAX_MATCH bytes 1831 * for the next match, plus MIN_MATCH bytes to insert the 1832 * string following the next match. 1833 */ 1834 if (s->lookahead < MIN_LOOKAHEAD) { 1835 fill_window(s); 1836 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1837 return need_more; 1838 } 1839 if (s->lookahead == 0) break; /* flush the current block */ 1840 } 1841 1842 /* Insert the string window[strstart .. strstart + 2] in the 1843 * dictionary, and set hash_head to the head of the hash chain: 1844 */ 1845 hash_head = NIL; 1846 if (s->lookahead >= MIN_MATCH) { 1847 INSERT_STRING(s, s->strstart, hash_head); 1848 } 1849 1850 /* Find the longest match, discarding those <= prev_length. 1851 * At this point we have always match_length < MIN_MATCH 1852 */ 1853 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1854 /* To simplify the code, we prevent matches with the string 1855 * of window index 0 (in particular we have to avoid a match 1856 * of the string with itself at the start of the input file). 1857 */ 1858 s->match_length = longest_match (s, hash_head); 1859 /* longest_match() sets match_start */ 1860 } 1861 if (s->match_length >= MIN_MATCH) { 1862 check_match(s, s->strstart, s->match_start, s->match_length); 1863 1864 _tr_tally_dist(s, s->strstart - s->match_start, 1865 s->match_length - MIN_MATCH, bflush); 1866 1867 s->lookahead -= s->match_length; 1868 1869 /* Insert new strings in the hash table only if the match length 1870 * is not too large. This saves time but degrades compression. 1871 */ 1872#ifndef FASTEST 1873 if (s->match_length <= s->max_insert_length && 1874 s->lookahead >= MIN_MATCH) { 1875 s->match_length--; /* string at strstart already in table */ 1876 do { 1877 s->strstart++; 1878 INSERT_STRING(s, s->strstart, hash_head); 1879 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1880 * always MIN_MATCH bytes ahead. 1881 */ 1882 } while (--s->match_length != 0); 1883 s->strstart++; 1884 } else 1885#endif 1886 { 1887 s->strstart += s->match_length; 1888 s->match_length = 0; 1889 s->ins_h = s->window[s->strstart]; 1890 UPDATE_HASH(s, s->ins_h, s->window[s->strstart + 1]); 1891#if MIN_MATCH != 3 1892 Call UPDATE_HASH() MIN_MATCH-3 more times 1893#endif 1894 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1895 * matter since it will be recomputed at next deflate call. 1896 */ 1897 } 1898 } else { 1899 /* No match, output a literal byte */ 1900 Tracevv((stderr,"%c", s->window[s->strstart])); 1901 _tr_tally_lit(s, s->window[s->strstart], bflush); 1902 s->lookahead--; 1903 s->strstart++; 1904 } 1905 if (bflush) FLUSH_BLOCK(s, 0); 1906 } 1907 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1908 if (flush == Z_FINISH) { 1909 FLUSH_BLOCK(s, 1); 1910 return finish_done; 1911 } 1912 if (s->sym_next) 1913 FLUSH_BLOCK(s, 0); 1914 return block_done; 1915} 1916 1917#ifndef FASTEST 1918/* =========================================================================== 1919 * Same as above, but achieves better compression. We use a lazy 1920 * evaluation for matches: a match is finally adopted only if there is 1921 * no better match at the next window position. 1922 */ 1923local block_state deflate_slow(deflate_state *s, int flush) 1924{ 1925 IPos hash_head; /* head of hash chain */ 1926 int bflush; /* set if current block must be flushed */ 1927 1928 /* Process the input block. */ 1929 for (;;) { 1930 /* Make sure that we always have enough lookahead, except 1931 * at the end of the input file. We need MAX_MATCH bytes 1932 * for the next match, plus MIN_MATCH bytes to insert the 1933 * string following the next match. 1934 */ 1935 if (s->lookahead < MIN_LOOKAHEAD) { 1936 fill_window(s); 1937 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1938 return need_more; 1939 } 1940 if (s->lookahead == 0) break; /* flush the current block */ 1941 } 1942 1943 /* Insert the string window[strstart .. strstart + 2] in the 1944 * dictionary, and set hash_head to the head of the hash chain: 1945 */ 1946 hash_head = NIL; 1947 if (s->lookahead >= MIN_MATCH) { 1948 INSERT_STRING(s, s->strstart, hash_head); 1949 } 1950 1951 /* Find the longest match, discarding those <= prev_length. 1952 */ 1953 s->prev_length = s->match_length, s->prev_match = s->match_start; 1954 s->match_length = MIN_MATCH-1; 1955 1956 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1957 s->strstart - hash_head <= MAX_DIST(s)) { 1958 /* To simplify the code, we prevent matches with the string 1959 * of window index 0 (in particular we have to avoid a match 1960 * of the string with itself at the start of the input file). 1961 */ 1962 s->match_length = longest_match (s, hash_head); 1963 /* longest_match() sets match_start */ 1964 1965 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1966#if TOO_FAR <= 32767 1967 || (s->match_length == MIN_MATCH && 1968 s->strstart - s->match_start > TOO_FAR) 1969#endif 1970 )) { 1971 1972 /* If prev_match is also MIN_MATCH, match_start is garbage 1973 * but we will ignore the current match anyway. 1974 */ 1975 s->match_length = MIN_MATCH-1; 1976 } 1977 } 1978 /* If there was a match at the previous step and the current 1979 * match is not better, output the previous match: 1980 */ 1981 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1982 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1983 /* Do not insert strings in hash table beyond this. */ 1984 1985 check_match(s, s->strstart - 1, s->prev_match, s->prev_length); 1986 1987 _tr_tally_dist(s, s->strstart - 1 - s->prev_match, 1988 s->prev_length - MIN_MATCH, bflush); 1989 1990 /* Insert in hash table all strings up to the end of the match. 1991 * strstart - 1 and strstart are already inserted. If there is not 1992 * enough lookahead, the last two strings are not inserted in 1993 * the hash table. 1994 */ 1995 s->lookahead -= s->prev_length - 1; 1996 s->prev_length -= 2; 1997 do { 1998 if (++s->strstart <= max_insert) { 1999 INSERT_STRING(s, s->strstart, hash_head); 2000 } 2001 } while (--s->prev_length != 0); 2002 s->match_available = 0; 2003 s->match_length = MIN_MATCH-1; 2004 s->strstart++; 2005 2006 if (bflush) FLUSH_BLOCK(s, 0); 2007 2008 } else if (s->match_available) { 2009 /* If there was no match at the previous position, output a 2010 * single literal. If there was a match but the current match 2011 * is longer, truncate the previous match to a single literal. 2012 */ 2013 Tracevv((stderr,"%c", s->window[s->strstart - 1])); 2014 _tr_tally_lit(s, s->window[s->strstart - 1], bflush); 2015 if (bflush) { 2016 FLUSH_BLOCK_ONLY(s, 0); 2017 } 2018 s->strstart++; 2019 s->lookahead--; 2020 if (s->strm->avail_out == 0) return need_more; 2021 } else { 2022 /* There is no previous match to compare with, wait for 2023 * the next step to decide. 2024 */ 2025 s->match_available = 1; 2026 s->strstart++; 2027 s->lookahead--; 2028 } 2029 } 2030 Assert (flush != Z_NO_FLUSH, "no flush?"); 2031 if (s->match_available) { 2032 Tracevv((stderr,"%c", s->window[s->strstart - 1])); 2033 _tr_tally_lit(s, s->window[s->strstart - 1], bflush); 2034 s->match_available = 0; 2035 } 2036 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 2037 if (flush == Z_FINISH) { 2038 FLUSH_BLOCK(s, 1); 2039 return finish_done; 2040 } 2041 if (s->sym_next) 2042 FLUSH_BLOCK(s, 0); 2043 return block_done; 2044} 2045#endif /* FASTEST */ 2046 2047/* =========================================================================== 2048 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 2049 * one. Do not maintain a hash table. (It will be regenerated if this run of 2050 * deflate switches away from Z_RLE.) 2051 */ 2052local block_state deflate_rle(deflate_state *s, int flush) 2053{ 2054 int bflush; /* set if current block must be flushed */ 2055 uInt prev; /* byte at distance one to match */ 2056 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 2057 2058 for (;;) { 2059 /* Make sure that we always have enough lookahead, except 2060 * at the end of the input file. We need MAX_MATCH bytes 2061 * for the longest run, plus one for the unrolled loop. 2062 */ 2063 if (s->lookahead <= MAX_MATCH) { 2064 fill_window(s); 2065 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 2066 return need_more; 2067 } 2068 if (s->lookahead == 0) break; /* flush the current block */ 2069 } 2070 2071 /* See how many times the previous byte repeats */ 2072 s->match_length = 0; 2073 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 2074 scan = s->window + s->strstart - 1; 2075 prev = *scan; 2076 if (prev == *++scan && prev == *++scan && prev == *++scan) { 2077 strend = s->window + s->strstart + MAX_MATCH; 2078 do { 2079 } while (prev == *++scan && prev == *++scan && 2080 prev == *++scan && prev == *++scan && 2081 prev == *++scan && prev == *++scan && 2082 prev == *++scan && prev == *++scan && 2083 scan < strend); 2084 s->match_length = MAX_MATCH - (uInt)(strend - scan); 2085 if (s->match_length > s->lookahead) 2086 s->match_length = s->lookahead; 2087 } 2088 Assert(scan <= s->window + (uInt)(s->window_size - 1), 2089 "wild scan"); 2090 } 2091 2092 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 2093 if (s->match_length >= MIN_MATCH) { 2094 check_match(s, s->strstart, s->strstart - 1, s->match_length); 2095 2096 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 2097 2098 s->lookahead -= s->match_length; 2099 s->strstart += s->match_length; 2100 s->match_length = 0; 2101 } else { 2102 /* No match, output a literal byte */ 2103 Tracevv((stderr,"%c", s->window[s->strstart])); 2104 _tr_tally_lit(s, s->window[s->strstart], bflush); 2105 s->lookahead--; 2106 s->strstart++; 2107 } 2108 if (bflush) FLUSH_BLOCK(s, 0); 2109 } 2110 s->insert = 0; 2111 if (flush == Z_FINISH) { 2112 FLUSH_BLOCK(s, 1); 2113 return finish_done; 2114 } 2115 if (s->sym_next) 2116 FLUSH_BLOCK(s, 0); 2117 return block_done; 2118} 2119 2120/* =========================================================================== 2121 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 2122 * (It will be regenerated if this run of deflate switches away from Huffman.) 2123 */ 2124local block_state deflate_huff(deflate_state *s, int flush) 2125{ 2126 int bflush; /* set if current block must be flushed */ 2127 2128 for (;;) { 2129 /* Make sure that we have a literal to write. */ 2130 if (s->lookahead == 0) { 2131 fill_window(s); 2132 if (s->lookahead == 0) { 2133 if (flush == Z_NO_FLUSH) 2134 return need_more; 2135 break; /* flush the current block */ 2136 } 2137 } 2138 2139 /* Output a literal byte */ 2140 s->match_length = 0; 2141 Tracevv((stderr,"%c", s->window[s->strstart])); 2142 _tr_tally_lit(s, s->window[s->strstart], bflush); 2143 s->lookahead--; 2144 s->strstart++; 2145 if (bflush) FLUSH_BLOCK(s, 0); 2146 } 2147 s->insert = 0; 2148 if (flush == Z_FINISH) { 2149 FLUSH_BLOCK(s, 1); 2150 return finish_done; 2151 } 2152 if (s->sym_next) 2153 FLUSH_BLOCK(s, 0); 2154 return block_done; 2155} 2156