1 /* deflate.c -- compress data using the deflation algorithm 2 * Copyright (C) 1995-2017 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 54 const char deflate_copyright[] = 55 " deflate 1.2.11 Copyright 1995-2017 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 63 /* =========================================================================== 64 * Function prototypes. 65 */ 66 typedef enum { 67 need_more, /* block not completed, need more input or more output */ 68 block_done, /* block flush performed */ 69 finish_started, /* finish started, need only more output at next deflate */ 70 finish_done /* finish done, accept no more input or output */ 71 } block_state; 72 73 typedef block_state (*compress_func) OF((deflate_state *s, int flush)); 74 /* Compression function. Returns the block state after the call. */ 75 76 local int deflateStateCheck OF((z_streamp strm)); 77 local void slide_hash OF((deflate_state *s)); 78 local void fill_window OF((deflate_state *s)); 79 local block_state deflate_stored OF((deflate_state *s, int flush)); 80 local block_state deflate_fast OF((deflate_state *s, int flush)); 81 #ifndef FASTEST 82 local block_state deflate_slow OF((deflate_state *s, int flush)); 83 #endif 84 local block_state deflate_rle OF((deflate_state *s, int flush)); 85 local block_state deflate_huff OF((deflate_state *s, int flush)); 86 local void lm_init OF((deflate_state *s)); 87 local void putShortMSB OF((deflate_state *s, uInt b)); 88 local void flush_pending OF((z_streamp strm)); 89 local unsigned read_buf OF((z_streamp strm, Bytef *buf, unsigned size)); 90 #ifdef ASMV 91 # pragma message("Assembler code may have bugs -- use at your own risk") 92 void match_init OF((void)); /* asm code initialization */ 93 uInt longest_match OF((deflate_state *s, IPos cur_match)); 94 #else 95 local uInt longest_match OF((deflate_state *s, IPos cur_match)); 96 #endif 97 98 #ifdef ZLIB_DEBUG 99 local void check_match OF((deflate_state *s, IPos start, IPos match, 100 int length)); 101 #endif 102 103 /* =========================================================================== 104 * Local data 105 */ 106 107 #define NIL 0 108 /* Tail of hash chains */ 109 110 #ifndef TOO_FAR 111 # define TOO_FAR 4096 112 #endif 113 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ 114 115 /* Values for max_lazy_match, good_match and max_chain_length, depending on 116 * the desired pack level (0..9). The values given below have been tuned to 117 * exclude worst case performance for pathological files. Better values may be 118 * found for specific files. 119 */ 120 typedef struct config_s { 121 ush good_length; /* reduce lazy search above this match length */ 122 ush max_lazy; /* do not perform lazy search above this match length */ 123 ush nice_length; /* quit search above this match length */ 124 ush max_chain; 125 compress_func func; 126 } config; 127 128 #ifdef FASTEST 129 local const config configuration_table[2] = { 130 /* good lazy nice chain */ 131 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 132 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ 133 #else 134 local const config configuration_table[10] = { 135 /* good lazy nice chain */ 136 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 137 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ 138 /* 2 */ {4, 5, 16, 8, deflate_fast}, 139 /* 3 */ {4, 6, 32, 32, deflate_fast}, 140 141 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ 142 /* 5 */ {8, 16, 32, 32, deflate_slow}, 143 /* 6 */ {8, 16, 128, 128, deflate_slow}, 144 /* 7 */ {8, 32, 128, 256, deflate_slow}, 145 /* 8 */ {32, 128, 258, 1024, deflate_slow}, 146 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ 147 #endif 148 149 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 150 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different 151 * meaning. 152 */ 153 154 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */ 155 #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0)) 156 157 /* =========================================================================== 158 * Update a hash value with the given input byte 159 * IN assertion: all calls to UPDATE_HASH are made with consecutive input 160 * characters, so that a running hash key can be computed from the previous 161 * key instead of complete recalculation each time. 162 */ 163 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask) 164 165 166 /* =========================================================================== 167 * Insert string str in the dictionary and set match_head to the previous head 168 * of the hash chain (the most recent string with same hash key). Return 169 * the previous length of the hash chain. 170 * If this file is compiled with -DFASTEST, the compression level is forced 171 * to 1, and no hash chains are maintained. 172 * IN assertion: all calls to INSERT_STRING are made with consecutive input 173 * characters and the first MIN_MATCH bytes of str are valid (except for 174 * the last MIN_MATCH-1 bytes of the input file). 175 */ 176 #ifdef FASTEST 177 #define INSERT_STRING(s, str, match_head) \ 178 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 179 match_head = s->head[s->ins_h], \ 180 s->head[s->ins_h] = (Pos)(str)) 181 #else 182 #define INSERT_STRING(s, str, match_head) \ 183 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 184 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ 185 s->head[s->ins_h] = (Pos)(str)) 186 #endif 187 188 /* =========================================================================== 189 * Initialize the hash table (avoiding 64K overflow for 16 bit systems). 190 * prev[] will be initialized on the fly. 191 */ 192 #define CLEAR_HASH(s) \ 193 s->head[s->hash_size-1] = NIL; \ 194 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head)); 195 196 /* =========================================================================== 197 * Slide the hash table when sliding the window down (could be avoided with 32 198 * bit values at the expense of memory usage). We slide even when level == 0 to 199 * keep the hash table consistent if we switch back to level > 0 later. 200 */ 201 local void slide_hash( 202 deflate_state *s) 203 { 204 unsigned n, m; 205 Posf *p; 206 uInt wsize = s->w_size; 207 208 n = s->hash_size; 209 p = &s->head[n]; 210 do { 211 m = *--p; 212 *p = (Pos)(m >= wsize ? m - wsize : NIL); 213 } while (--n); 214 n = wsize; 215 #ifndef FASTEST 216 p = &s->prev[n]; 217 do { 218 m = *--p; 219 *p = (Pos)(m >= wsize ? m - wsize : NIL); 220 /* If n is not on any hash chain, prev[n] is garbage but 221 * its value will never be used. 222 */ 223 } while (--n); 224 #endif 225 } 226 227 /* ========================================================================= */ 228 int ZEXPORT deflateInit_( 229 z_streamp strm, 230 int level, 231 const char *version, 232 int stream_size) 233 { 234 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, 235 Z_DEFAULT_STRATEGY, version, stream_size); 236 /* To do: ignore strm->next_in if we use it as window */ 237 } 238 239 /* ========================================================================= */ 240 int ZEXPORT deflateInit2_( 241 z_streamp strm, 242 int level, 243 int method, 244 int windowBits, 245 int memLevel, 246 int strategy, 247 const char *version, 248 int stream_size) 249 { 250 deflate_state *s; 251 int wrap = 1; 252 static const char my_version[] = ZLIB_VERSION; 253 254 ushf *overlay; 255 /* We overlay pending_buf and d_buf+l_buf. This works since the average 256 * output size for (length,distance) codes is <= 24 bits. 257 */ 258 259 if (version == Z_NULL || version[0] != my_version[0] || 260 stream_size != sizeof(z_stream)) { 261 return Z_VERSION_ERROR; 262 } 263 if (strm == Z_NULL) return Z_STREAM_ERROR; 264 265 strm->msg = Z_NULL; 266 if (strm->zalloc == (alloc_func)0) { 267 #ifdef Z_SOLO 268 return Z_STREAM_ERROR; 269 #else 270 strm->zalloc = zcalloc; 271 strm->opaque = (voidpf)0; 272 #endif 273 } 274 if (strm->zfree == (free_func)0) 275 #ifdef Z_SOLO 276 return Z_STREAM_ERROR; 277 #else 278 strm->zfree = zcfree; 279 #endif 280 281 #ifdef FASTEST 282 if (level != 0) level = 1; 283 #else 284 if (level == Z_DEFAULT_COMPRESSION) level = 6; 285 #endif 286 287 if (windowBits < 0) { /* suppress zlib wrapper */ 288 wrap = 0; 289 windowBits = -windowBits; 290 } 291 #ifdef GZIP 292 else if (windowBits > 15) { 293 wrap = 2; /* write gzip wrapper instead */ 294 windowBits -= 16; 295 } 296 #endif 297 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 298 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 299 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) { 300 return Z_STREAM_ERROR; 301 } 302 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 303 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 304 if (s == Z_NULL) return Z_MEM_ERROR; 305 strm->state = (struct internal_state FAR *)s; 306 s->strm = strm; 307 s->status = INIT_STATE; /* to pass state test in deflateReset() */ 308 309 s->wrap = wrap; 310 s->gzhead = Z_NULL; 311 s->w_bits = (uInt)windowBits; 312 s->w_size = 1 << s->w_bits; 313 s->w_mask = s->w_size - 1; 314 315 s->hash_bits = (uInt)memLevel + 7; 316 s->hash_size = 1 << s->hash_bits; 317 s->hash_mask = s->hash_size - 1; 318 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); 319 320 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 321 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 322 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 323 324 s->high_water = 0; /* nothing written to s->window yet */ 325 326 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 327 328 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); 329 s->pending_buf = (uchf *) overlay; 330 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); 331 332 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 333 s->pending_buf == Z_NULL) { 334 s->status = FINISH_STATE; 335 strm->msg = ERR_MSG(Z_MEM_ERROR); 336 deflateEnd (strm); 337 return Z_MEM_ERROR; 338 } 339 s->d_buf = overlay + s->lit_bufsize/sizeof(ush); 340 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; 341 342 s->level = level; 343 s->strategy = strategy; 344 s->method = (Byte)method; 345 346 return deflateReset(strm); 347 } 348 349 /* ========================================================================= 350 * Check for a valid deflate stream state. Return 0 if ok, 1 if not. 351 */ 352 local int deflateStateCheck ( 353 z_streamp strm) 354 { 355 deflate_state *s; 356 if (strm == Z_NULL || 357 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) 358 return 1; 359 s = strm->state; 360 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE && 361 #ifdef GZIP 362 s->status != GZIP_STATE && 363 #endif 364 s->status != EXTRA_STATE && 365 s->status != NAME_STATE && 366 s->status != COMMENT_STATE && 367 s->status != HCRC_STATE && 368 s->status != BUSY_STATE && 369 s->status != FINISH_STATE)) 370 return 1; 371 return 0; 372 } 373 374 /* ========================================================================= */ 375 int ZEXPORT deflateSetDictionary ( 376 z_streamp strm, 377 const Bytef *dictionary, 378 uInt dictLength) 379 { 380 deflate_state *s; 381 uInt str, n; 382 int wrap; 383 unsigned avail; 384 z_const unsigned char *next; 385 386 if (deflateStateCheck(strm) || dictionary == Z_NULL) 387 return Z_STREAM_ERROR; 388 s = strm->state; 389 wrap = s->wrap; 390 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) 391 return Z_STREAM_ERROR; 392 393 /* when using zlib wrappers, compute Adler-32 for provided dictionary */ 394 if (wrap == 1) 395 strm->adler = adler32(strm->adler, dictionary, dictLength); 396 s->wrap = 0; /* avoid computing Adler-32 in read_buf */ 397 398 /* if dictionary would fill window, just replace the history */ 399 if (dictLength >= s->w_size) { 400 if (wrap == 0) { /* already empty otherwise */ 401 CLEAR_HASH(s); 402 s->strstart = 0; 403 s->block_start = 0L; 404 s->insert = 0; 405 } 406 dictionary += dictLength - s->w_size; /* use the tail */ 407 dictLength = s->w_size; 408 } 409 410 /* insert dictionary into window and hash */ 411 avail = strm->avail_in; 412 next = strm->next_in; 413 strm->avail_in = dictLength; 414 strm->next_in = (z_const Bytef *)dictionary; 415 fill_window(s); 416 while (s->lookahead >= MIN_MATCH) { 417 str = s->strstart; 418 n = s->lookahead - (MIN_MATCH-1); 419 do { 420 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 421 #ifndef FASTEST 422 s->prev[str & s->w_mask] = s->head[s->ins_h]; 423 #endif 424 s->head[s->ins_h] = (Pos)str; 425 str++; 426 } while (--n); 427 s->strstart = str; 428 s->lookahead = MIN_MATCH-1; 429 fill_window(s); 430 } 431 s->strstart += s->lookahead; 432 s->block_start = (long)s->strstart; 433 s->insert = s->lookahead; 434 s->lookahead = 0; 435 s->match_length = s->prev_length = MIN_MATCH-1; 436 s->match_available = 0; 437 strm->next_in = next; 438 strm->avail_in = avail; 439 s->wrap = wrap; 440 return Z_OK; 441 } 442 443 /* ========================================================================= */ 444 int ZEXPORT deflateGetDictionary ( 445 z_streamp strm, 446 Bytef *dictionary, 447 uInt *dictLength) 448 { 449 deflate_state *s; 450 uInt len; 451 452 if (deflateStateCheck(strm)) 453 return Z_STREAM_ERROR; 454 s = strm->state; 455 len = s->strstart + s->lookahead; 456 if (len > s->w_size) 457 len = s->w_size; 458 if (dictionary != Z_NULL && len) 459 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len); 460 if (dictLength != Z_NULL) 461 *dictLength = len; 462 return Z_OK; 463 } 464 465 /* ========================================================================= */ 466 int ZEXPORT deflateResetKeep ( 467 z_streamp strm) 468 { 469 deflate_state *s; 470 471 if (deflateStateCheck(strm)) { 472 return Z_STREAM_ERROR; 473 } 474 475 strm->total_in = strm->total_out = 0; 476 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 477 strm->data_type = Z_UNKNOWN; 478 479 s = (deflate_state *)strm->state; 480 s->pending = 0; 481 s->pending_out = s->pending_buf; 482 483 if (s->wrap < 0) { 484 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 485 } 486 s->status = 487 #ifdef GZIP 488 s->wrap == 2 ? GZIP_STATE : 489 #endif 490 s->wrap ? INIT_STATE : BUSY_STATE; 491 strm->adler = 492 #ifdef GZIP 493 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 494 #endif 495 adler32(0L, Z_NULL, 0); 496 s->last_flush = Z_NO_FLUSH; 497 498 _tr_init(s); 499 500 return Z_OK; 501 } 502 503 /* ========================================================================= */ 504 int ZEXPORT deflateReset ( 505 z_streamp strm) 506 { 507 int ret; 508 509 ret = deflateResetKeep(strm); 510 if (ret == Z_OK) 511 lm_init(strm->state); 512 return ret; 513 } 514 515 /* ========================================================================= */ 516 int ZEXPORT deflateSetHeader ( 517 z_streamp strm, 518 gz_headerp head) 519 { 520 if (deflateStateCheck(strm) || strm->state->wrap != 2) 521 return Z_STREAM_ERROR; 522 strm->state->gzhead = head; 523 return Z_OK; 524 } 525 526 /* ========================================================================= */ 527 int ZEXPORT deflatePending ( 528 z_streamp strm, 529 unsigned *pending, 530 int *bits) 531 { 532 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 533 if (pending != Z_NULL) 534 *pending = strm->state->pending; 535 if (bits != Z_NULL) 536 *bits = strm->state->bi_valid; 537 return Z_OK; 538 } 539 540 /* ========================================================================= */ 541 int ZEXPORT deflatePrime ( 542 z_streamp strm, 543 int bits, 544 int value) 545 { 546 deflate_state *s; 547 int put; 548 549 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 550 s = strm->state; 551 if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3)) 552 return Z_BUF_ERROR; 553 do { 554 put = Buf_size - s->bi_valid; 555 if (put > bits) 556 put = bits; 557 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); 558 s->bi_valid += put; 559 _tr_flush_bits(s); 560 value >>= put; 561 bits -= put; 562 } while (bits); 563 return Z_OK; 564 } 565 566 /* ========================================================================= */ 567 int ZEXPORT deflateParams( 568 z_streamp strm, 569 int level, 570 int strategy) 571 { 572 deflate_state *s; 573 compress_func func; 574 575 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 576 s = strm->state; 577 578 #ifdef FASTEST 579 if (level != 0) level = 1; 580 #else 581 if (level == Z_DEFAULT_COMPRESSION) level = 6; 582 #endif 583 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 584 return Z_STREAM_ERROR; 585 } 586 func = configuration_table[s->level].func; 587 588 if ((strategy != s->strategy || func != configuration_table[level].func) && 589 s->high_water) { 590 /* Flush the last buffer: */ 591 int err = deflate(strm, Z_BLOCK); 592 if (err == Z_STREAM_ERROR) 593 return err; 594 if (strm->avail_out == 0) 595 return Z_BUF_ERROR; 596 } 597 if (s->level != level) { 598 if (s->level == 0 && s->matches != 0) { 599 if (s->matches == 1) 600 slide_hash(s); 601 else 602 CLEAR_HASH(s); 603 s->matches = 0; 604 } 605 s->level = level; 606 s->max_lazy_match = configuration_table[level].max_lazy; 607 s->good_match = configuration_table[level].good_length; 608 s->nice_match = configuration_table[level].nice_length; 609 s->max_chain_length = configuration_table[level].max_chain; 610 } 611 s->strategy = strategy; 612 return Z_OK; 613 } 614 615 /* ========================================================================= */ 616 int ZEXPORT deflateTune( 617 z_streamp strm, 618 int good_length, 619 int max_lazy, 620 int nice_length, 621 int max_chain) 622 { 623 deflate_state *s; 624 625 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 626 s = strm->state; 627 s->good_match = (uInt)good_length; 628 s->max_lazy_match = (uInt)max_lazy; 629 s->nice_match = nice_length; 630 s->max_chain_length = (uInt)max_chain; 631 return Z_OK; 632 } 633 634 /* ========================================================================= 635 * For the default windowBits of 15 and memLevel of 8, this function returns 636 * a close to exact, as well as small, upper bound on the compressed size. 637 * They are coded as constants here for a reason--if the #define's are 638 * changed, then this function needs to be changed as well. The return 639 * value for 15 and 8 only works for those exact settings. 640 * 641 * For any setting other than those defaults for windowBits and memLevel, 642 * the value returned is a conservative worst case for the maximum expansion 643 * resulting from using fixed blocks instead of stored blocks, which deflate 644 * can emit on compressed data for some combinations of the parameters. 645 * 646 * This function could be more sophisticated to provide closer upper bounds for 647 * every combination of windowBits and memLevel. But even the conservative 648 * upper bound of about 14% expansion does not seem onerous for output buffer 649 * allocation. 650 */ 651 uLong ZEXPORT deflateBound( 652 z_streamp strm, 653 uLong sourceLen) 654 { 655 deflate_state *s; 656 uLong complen, wraplen; 657 658 /* conservative upper bound for compressed data */ 659 complen = sourceLen + 660 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5; 661 662 /* if can't get parameters, return conservative bound plus zlib wrapper */ 663 if (deflateStateCheck(strm)) 664 return complen + 6; 665 666 /* compute wrapper length */ 667 s = strm->state; 668 switch (s->wrap) { 669 case 0: /* raw deflate */ 670 wraplen = 0; 671 break; 672 case 1: /* zlib wrapper */ 673 wraplen = 6 + (s->strstart ? 4 : 0); 674 break; 675 #ifdef GZIP 676 case 2: /* gzip wrapper */ 677 wraplen = 18; 678 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 679 Bytef *str; 680 if (s->gzhead->extra != Z_NULL) 681 wraplen += 2 + s->gzhead->extra_len; 682 str = s->gzhead->name; 683 if (str != Z_NULL) 684 do { 685 wraplen++; 686 } while (*str++); 687 str = s->gzhead->comment; 688 if (str != Z_NULL) 689 do { 690 wraplen++; 691 } while (*str++); 692 if (s->gzhead->hcrc) 693 wraplen += 2; 694 } 695 break; 696 #endif 697 default: /* for compiler happiness */ 698 wraplen = 6; 699 } 700 701 /* if not default parameters, return conservative bound */ 702 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 703 return complen + wraplen; 704 705 /* default settings: return tight bound for that case */ 706 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 707 (sourceLen >> 25) + 13 - 6 + wraplen; 708 } 709 710 /* ========================================================================= 711 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 712 * IN assertion: the stream state is correct and there is enough room in 713 * pending_buf. 714 */ 715 local void putShortMSB ( 716 deflate_state *s, 717 uInt b) 718 { 719 put_byte(s, (Byte)(b >> 8)); 720 put_byte(s, (Byte)(b & 0xff)); 721 } 722 723 /* ========================================================================= 724 * Flush as much pending output as possible. All deflate() output, except for 725 * some deflate_stored() output, goes through this function so some 726 * applications may wish to modify it to avoid allocating a large 727 * strm->next_out buffer and copying into it. (See also read_buf()). 728 */ 729 local void flush_pending( 730 z_streamp strm) 731 { 732 unsigned len; 733 deflate_state *s = strm->state; 734 735 _tr_flush_bits(s); 736 len = s->pending; 737 if (len > strm->avail_out) len = strm->avail_out; 738 if (len == 0) return; 739 740 zmemcpy(strm->next_out, s->pending_out, len); 741 strm->next_out += len; 742 s->pending_out += len; 743 strm->total_out += len; 744 strm->avail_out -= len; 745 s->pending -= len; 746 if (s->pending == 0) { 747 s->pending_out = s->pending_buf; 748 } 749 } 750 751 /* =========================================================================== 752 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1]. 753 */ 754 #define HCRC_UPDATE(beg) \ 755 do { \ 756 if (s->gzhead->hcrc && s->pending > (beg)) \ 757 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \ 758 s->pending - (beg)); \ 759 } while (0) 760 761 /* ========================================================================= */ 762 int ZEXPORT deflate ( 763 z_streamp strm, 764 int flush) 765 { 766 int old_flush; /* value of flush param for previous deflate call */ 767 deflate_state *s; 768 769 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { 770 return Z_STREAM_ERROR; 771 } 772 s = strm->state; 773 774 if (strm->next_out == Z_NULL || 775 (strm->avail_in != 0 && strm->next_in == Z_NULL) || 776 (s->status == FINISH_STATE && flush != Z_FINISH)) { 777 ERR_RETURN(strm, Z_STREAM_ERROR); 778 } 779 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 780 781 old_flush = s->last_flush; 782 s->last_flush = flush; 783 784 /* Flush as much pending output as possible */ 785 if (s->pending != 0) { 786 flush_pending(strm); 787 if (strm->avail_out == 0) { 788 /* Since avail_out is 0, deflate will be called again with 789 * more output space, but possibly with both pending and 790 * avail_in equal to zero. There won't be anything to do, 791 * but this is not an error situation so make sure we 792 * return OK instead of BUF_ERROR at next call of deflate: 793 */ 794 s->last_flush = -1; 795 return Z_OK; 796 } 797 798 /* Make sure there is something to do and avoid duplicate consecutive 799 * flushes. For repeated and useless calls with Z_FINISH, we keep 800 * returning Z_STREAM_END instead of Z_BUF_ERROR. 801 */ 802 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 803 flush != Z_FINISH) { 804 ERR_RETURN(strm, Z_BUF_ERROR); 805 } 806 807 /* User must not provide more input after the first FINISH: */ 808 if (s->status == FINISH_STATE && strm->avail_in != 0) { 809 ERR_RETURN(strm, Z_BUF_ERROR); 810 } 811 812 /* Write the header */ 813 if (s->status == INIT_STATE) { 814 /* zlib header */ 815 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; 816 uInt level_flags; 817 818 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 819 level_flags = 0; 820 else if (s->level < 6) 821 level_flags = 1; 822 else if (s->level == 6) 823 level_flags = 2; 824 else 825 level_flags = 3; 826 header |= (level_flags << 6); 827 if (s->strstart != 0) header |= PRESET_DICT; 828 header += 31 - (header % 31); 829 830 putShortMSB(s, header); 831 832 /* Save the adler32 of the preset dictionary: */ 833 if (s->strstart != 0) { 834 putShortMSB(s, (uInt)(strm->adler >> 16)); 835 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 836 } 837 strm->adler = adler32(0L, Z_NULL, 0); 838 s->status = BUSY_STATE; 839 840 /* Compression must start with an empty pending buffer */ 841 flush_pending(strm); 842 if (s->pending != 0) { 843 s->last_flush = -1; 844 return Z_OK; 845 } 846 } 847 #ifdef GZIP 848 if (s->status == GZIP_STATE) { 849 /* gzip header */ 850 strm->adler = crc32(0L, Z_NULL, 0); 851 put_byte(s, 31); 852 put_byte(s, 139); 853 put_byte(s, 8); 854 if (s->gzhead == Z_NULL) { 855 put_byte(s, 0); 856 put_byte(s, 0); 857 put_byte(s, 0); 858 put_byte(s, 0); 859 put_byte(s, 0); 860 put_byte(s, s->level == 9 ? 2 : 861 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 862 4 : 0)); 863 put_byte(s, OS_CODE); 864 s->status = BUSY_STATE; 865 866 /* Compression must start with an empty pending buffer */ 867 flush_pending(strm); 868 if (s->pending != 0) { 869 s->last_flush = -1; 870 return Z_OK; 871 } 872 } 873 else { 874 put_byte(s, (s->gzhead->text ? 1 : 0) + 875 (s->gzhead->hcrc ? 2 : 0) + 876 (s->gzhead->extra == Z_NULL ? 0 : 4) + 877 (s->gzhead->name == Z_NULL ? 0 : 8) + 878 (s->gzhead->comment == Z_NULL ? 0 : 16) 879 ); 880 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 881 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 882 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 883 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 884 put_byte(s, s->level == 9 ? 2 : 885 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 886 4 : 0)); 887 put_byte(s, s->gzhead->os & 0xff); 888 if (s->gzhead->extra != Z_NULL) { 889 put_byte(s, s->gzhead->extra_len & 0xff); 890 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 891 } 892 if (s->gzhead->hcrc) 893 strm->adler = crc32(strm->adler, s->pending_buf, 894 s->pending); 895 s->gzindex = 0; 896 s->status = EXTRA_STATE; 897 } 898 } 899 if (s->status == EXTRA_STATE) { 900 if (s->gzhead->extra != Z_NULL) { 901 ulg beg = s->pending; /* start of bytes to update crc */ 902 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex; 903 while (s->pending + left > s->pending_buf_size) { 904 uInt copy = s->pending_buf_size - s->pending; 905 zmemcpy(s->pending_buf + s->pending, 906 s->gzhead->extra + s->gzindex, copy); 907 s->pending = s->pending_buf_size; 908 HCRC_UPDATE(beg); 909 s->gzindex += copy; 910 flush_pending(strm); 911 if (s->pending != 0) { 912 s->last_flush = -1; 913 return Z_OK; 914 } 915 beg = 0; 916 left -= copy; 917 } 918 zmemcpy(s->pending_buf + s->pending, 919 s->gzhead->extra + s->gzindex, left); 920 s->pending += left; 921 HCRC_UPDATE(beg); 922 s->gzindex = 0; 923 } 924 s->status = NAME_STATE; 925 } 926 if (s->status == NAME_STATE) { 927 if (s->gzhead->name != Z_NULL) { 928 ulg beg = s->pending; /* start of bytes to update crc */ 929 int val; 930 do { 931 if (s->pending == s->pending_buf_size) { 932 HCRC_UPDATE(beg); 933 flush_pending(strm); 934 if (s->pending != 0) { 935 s->last_flush = -1; 936 return Z_OK; 937 } 938 beg = 0; 939 } 940 val = s->gzhead->name[s->gzindex++]; 941 put_byte(s, val); 942 } while (val != 0); 943 HCRC_UPDATE(beg); 944 s->gzindex = 0; 945 } 946 s->status = COMMENT_STATE; 947 } 948 if (s->status == COMMENT_STATE) { 949 if (s->gzhead->comment != Z_NULL) { 950 ulg beg = s->pending; /* start of bytes to update crc */ 951 int val; 952 do { 953 if (s->pending == s->pending_buf_size) { 954 HCRC_UPDATE(beg); 955 flush_pending(strm); 956 if (s->pending != 0) { 957 s->last_flush = -1; 958 return Z_OK; 959 } 960 beg = 0; 961 } 962 val = s->gzhead->comment[s->gzindex++]; 963 put_byte(s, val); 964 } while (val != 0); 965 HCRC_UPDATE(beg); 966 } 967 s->status = HCRC_STATE; 968 } 969 if (s->status == HCRC_STATE) { 970 if (s->gzhead->hcrc) { 971 if (s->pending + 2 > s->pending_buf_size) { 972 flush_pending(strm); 973 if (s->pending != 0) { 974 s->last_flush = -1; 975 return Z_OK; 976 } 977 } 978 put_byte(s, (Byte)(strm->adler & 0xff)); 979 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 980 strm->adler = crc32(0L, Z_NULL, 0); 981 } 982 s->status = BUSY_STATE; 983 984 /* Compression must start with an empty pending buffer */ 985 flush_pending(strm); 986 if (s->pending != 0) { 987 s->last_flush = -1; 988 return Z_OK; 989 } 990 } 991 #endif 992 993 /* Start a new block or continue the current one. 994 */ 995 if (strm->avail_in != 0 || s->lookahead != 0 || 996 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 997 block_state bstate; 998 999 bstate = s->level == 0 ? deflate_stored(s, flush) : 1000 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 1001 s->strategy == Z_RLE ? deflate_rle(s, flush) : 1002 (*(configuration_table[s->level].func))(s, flush); 1003 1004 if (bstate == finish_started || bstate == finish_done) { 1005 s->status = FINISH_STATE; 1006 } 1007 if (bstate == need_more || bstate == finish_started) { 1008 if (strm->avail_out == 0) { 1009 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 1010 } 1011 return Z_OK; 1012 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 1013 * of deflate should use the same flush parameter to make sure 1014 * that the flush is complete. So we don't have to output an 1015 * empty block here, this will be done at next call. This also 1016 * ensures that for a very small output buffer, we emit at most 1017 * one empty block. 1018 */ 1019 } 1020 if (bstate == block_done) { 1021 if (flush == Z_PARTIAL_FLUSH) { 1022 _tr_align(s); 1023 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 1024 _tr_stored_block(s, (char*)0, 0L, 0); 1025 /* For a full flush, this empty block will be recognized 1026 * as a special marker by inflate_sync(). 1027 */ 1028 if (flush == Z_FULL_FLUSH) { 1029 CLEAR_HASH(s); /* forget history */ 1030 if (s->lookahead == 0) { 1031 s->strstart = 0; 1032 s->block_start = 0L; 1033 s->insert = 0; 1034 } 1035 } 1036 } 1037 flush_pending(strm); 1038 if (strm->avail_out == 0) { 1039 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 1040 return Z_OK; 1041 } 1042 } 1043 } 1044 1045 if (flush != Z_FINISH) return Z_OK; 1046 if (s->wrap <= 0) return Z_STREAM_END; 1047 1048 /* Write the trailer */ 1049 #ifdef GZIP 1050 if (s->wrap == 2) { 1051 put_byte(s, (Byte)(strm->adler & 0xff)); 1052 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1053 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 1054 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 1055 put_byte(s, (Byte)(strm->total_in & 0xff)); 1056 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 1057 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 1058 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 1059 } 1060 else 1061 #endif 1062 { 1063 putShortMSB(s, (uInt)(strm->adler >> 16)); 1064 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1065 } 1066 flush_pending(strm); 1067 /* If avail_out is zero, the application will call deflate again 1068 * to flush the rest. 1069 */ 1070 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 1071 return s->pending != 0 ? Z_OK : Z_STREAM_END; 1072 } 1073 1074 /* ========================================================================= */ 1075 int ZEXPORT deflateEnd ( 1076 z_streamp strm) 1077 { 1078 int status; 1079 1080 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 1081 1082 status = strm->state->status; 1083 1084 /* Deallocate in reverse order of allocations: */ 1085 TRY_FREE(strm, strm->state->pending_buf); 1086 TRY_FREE(strm, strm->state->head); 1087 TRY_FREE(strm, strm->state->prev); 1088 TRY_FREE(strm, strm->state->window); 1089 1090 ZFREE(strm, strm->state); 1091 strm->state = Z_NULL; 1092 1093 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1094 } 1095 1096 /* ========================================================================= 1097 * Copy the source state to the destination state. 1098 * To simplify the source, this is not supported for 16-bit MSDOS (which 1099 * doesn't have enough memory anyway to duplicate compression states). 1100 */ 1101 int ZEXPORT deflateCopy ( 1102 z_streamp dest, 1103 z_streamp source) 1104 { 1105 #ifdef MAXSEG_64K 1106 return Z_STREAM_ERROR; 1107 #else 1108 deflate_state *ds; 1109 deflate_state *ss; 1110 ushf *overlay; 1111 1112 1113 if (deflateStateCheck(source) || dest == Z_NULL) { 1114 return Z_STREAM_ERROR; 1115 } 1116 1117 ss = source->state; 1118 1119 zmemcpy((Bytef*)dest, (Bytef*)source, sizeof(z_stream)); 1120 1121 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1122 if (ds == Z_NULL) return Z_MEM_ERROR; 1123 dest->state = (struct internal_state FAR *) ds; 1124 zmemcpy((Bytef*)ds, (Bytef*)ss, sizeof(deflate_state)); 1125 ds->strm = dest; 1126 1127 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1128 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1129 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1130 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); 1131 ds->pending_buf = (uchf *) overlay; 1132 1133 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1134 ds->pending_buf == Z_NULL) { 1135 deflateEnd (dest); 1136 return Z_MEM_ERROR; 1137 } 1138 /* following zmemcpy do not work for 16-bit MSDOS */ 1139 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1140 zmemcpy((Bytef*)ds->prev, (Bytef*)ss->prev, ds->w_size * sizeof(Pos)); 1141 zmemcpy((Bytef*)ds->head, (Bytef*)ss->head, ds->hash_size * sizeof(Pos)); 1142 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); 1143 1144 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1145 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); 1146 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; 1147 1148 ds->l_desc.dyn_tree = ds->dyn_ltree; 1149 ds->d_desc.dyn_tree = ds->dyn_dtree; 1150 ds->bl_desc.dyn_tree = ds->bl_tree; 1151 1152 return Z_OK; 1153 #endif /* MAXSEG_64K */ 1154 } 1155 1156 /* =========================================================================== 1157 * Read a new buffer from the current input stream, update the adler32 1158 * and total number of bytes read. All deflate() input goes through 1159 * this function so some applications may wish to modify it to avoid 1160 * allocating a large strm->next_in buffer and copying from it. 1161 * (See also flush_pending()). 1162 */ 1163 local unsigned read_buf( 1164 z_streamp strm, 1165 Bytef *buf, 1166 unsigned size) 1167 { 1168 unsigned len = strm->avail_in; 1169 1170 if (len > size) len = size; 1171 if (len == 0) return 0; 1172 1173 strm->avail_in -= len; 1174 1175 zmemcpy(buf, strm->next_in, len); 1176 if (strm->state->wrap == 1) { 1177 strm->adler = adler32(strm->adler, buf, len); 1178 } 1179 #ifdef GZIP 1180 else if (strm->state->wrap == 2) { 1181 strm->adler = crc32(strm->adler, buf, len); 1182 } 1183 #endif 1184 strm->next_in += len; 1185 strm->total_in += len; 1186 1187 return len; 1188 } 1189 1190 /* =========================================================================== 1191 * Initialize the "longest match" routines for a new zlib stream 1192 */ 1193 local void lm_init ( 1194 deflate_state *s) 1195 { 1196 s->window_size = (ulg)2L*s->w_size; 1197 1198 CLEAR_HASH(s); 1199 1200 /* Set the default configuration parameters: 1201 */ 1202 s->max_lazy_match = configuration_table[s->level].max_lazy; 1203 s->good_match = configuration_table[s->level].good_length; 1204 s->nice_match = configuration_table[s->level].nice_length; 1205 s->max_chain_length = configuration_table[s->level].max_chain; 1206 1207 s->strstart = 0; 1208 s->block_start = 0L; 1209 s->lookahead = 0; 1210 s->insert = 0; 1211 s->match_length = s->prev_length = MIN_MATCH-1; 1212 s->match_available = 0; 1213 s->ins_h = 0; 1214 #ifndef FASTEST 1215 #ifdef ASMV 1216 match_init(); /* initialize the asm code */ 1217 #endif 1218 #endif 1219 } 1220 1221 #ifndef FASTEST 1222 /* =========================================================================== 1223 * Set match_start to the longest match starting at the given string and 1224 * return its length. Matches shorter or equal to prev_length are discarded, 1225 * in which case the result is equal to prev_length and match_start is 1226 * garbage. 1227 * IN assertions: cur_match is the head of the hash chain for the current 1228 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1229 * OUT assertion: the match length is not greater than s->lookahead. 1230 */ 1231 #ifndef ASMV 1232 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or 1233 * match.S. The code will be functionally equivalent. 1234 */ 1235 local uInt longest_match( 1236 deflate_state *s, 1237 IPos cur_match) 1238 { 1239 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1240 register Bytef *scan = s->window + s->strstart; /* current string */ 1241 register Bytef *match; /* matched string */ 1242 register int len; /* length of current match */ 1243 int best_len = (int)s->prev_length; /* best match length so far */ 1244 int nice_match = s->nice_match; /* stop if match long enough */ 1245 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1246 s->strstart - (IPos)MAX_DIST(s) : NIL; 1247 /* Stop when cur_match becomes <= limit. To simplify the code, 1248 * we prevent matches with the string of window index 0. 1249 */ 1250 Posf *prev = s->prev; 1251 uInt wmask = s->w_mask; 1252 1253 #ifdef UNALIGNED_OK 1254 /* Compare two bytes at a time. Note: this is not always beneficial. 1255 * Try with and without -DUNALIGNED_OK to check. 1256 */ 1257 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1258 register ush scan_start = *(ushf*)scan; 1259 register ush scan_end = *(ushf*)(scan+best_len-1); 1260 #else 1261 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1262 register Byte scan_end1 = scan[best_len-1]; 1263 register Byte scan_end = scan[best_len]; 1264 #endif 1265 1266 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1267 * It is easy to get rid of this optimization if necessary. 1268 */ 1269 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1270 1271 /* Do not waste too much time if we already have a good match: */ 1272 if (s->prev_length >= s->good_match) { 1273 chain_length >>= 2; 1274 } 1275 /* Do not look for matches beyond the end of the input. This is necessary 1276 * to make deflate deterministic. 1277 */ 1278 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead; 1279 1280 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1281 1282 do { 1283 Assert(cur_match < s->strstart, "no future"); 1284 match = s->window + cur_match; 1285 1286 /* Skip to next match if the match length cannot increase 1287 * or if the match length is less than 2. Note that the checks below 1288 * for insufficient lookahead only occur occasionally for performance 1289 * reasons. Therefore uninitialized memory will be accessed, and 1290 * conditional jumps will be made that depend on those values. 1291 * However the length of the match is limited to the lookahead, so 1292 * the output of deflate is not affected by the uninitialized values. 1293 */ 1294 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1295 /* This code assumes sizeof(unsigned short) == 2. Do not use 1296 * UNALIGNED_OK if your compiler uses a different size. 1297 */ 1298 if (*(ushf*)(match+best_len-1) != scan_end || 1299 *(ushf*)match != scan_start) continue; 1300 1301 /* It is not necessary to compare scan[2] and match[2] since they are 1302 * always equal when the other bytes match, given that the hash keys 1303 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1304 * strstart+3, +5, ... up to strstart+257. We check for insufficient 1305 * lookahead only every 4th comparison; the 128th check will be made 1306 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is 1307 * necessary to put more guard bytes at the end of the window, or 1308 * to check more often for insufficient lookahead. 1309 */ 1310 Assert(scan[2] == match[2], "scan[2]?"); 1311 scan++, match++; 1312 do { 1313 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1314 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1315 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1316 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1317 scan < strend); 1318 /* The funny "do {}" generates better code on most compilers */ 1319 1320 /* Here, scan <= window+strstart+257 */ 1321 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1322 if (*scan == *match) scan++; 1323 1324 len = (MAX_MATCH - 1) - (int)(strend-scan); 1325 scan = strend - (MAX_MATCH-1); 1326 1327 #else /* UNALIGNED_OK */ 1328 1329 if (match[best_len] != scan_end || 1330 match[best_len-1] != scan_end1 || 1331 *match != *scan || 1332 *++match != scan[1]) continue; 1333 1334 /* The check at best_len-1 can be removed because it will be made 1335 * again later. (This heuristic is not always a win.) 1336 * It is not necessary to compare scan[2] and match[2] since they 1337 * are always equal when the other bytes match, given that 1338 * the hash keys are equal and that HASH_BITS >= 8. 1339 */ 1340 scan += 2, match++; 1341 Assert(*scan == *match, "match[2]?"); 1342 1343 /* We check for insufficient lookahead only every 8th comparison; 1344 * the 256th check will be made at strstart+258. 1345 */ 1346 do { 1347 } while (*++scan == *++match && *++scan == *++match && 1348 *++scan == *++match && *++scan == *++match && 1349 *++scan == *++match && *++scan == *++match && 1350 *++scan == *++match && *++scan == *++match && 1351 scan < strend); 1352 1353 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1354 1355 len = MAX_MATCH - (int)(strend - scan); 1356 scan = strend - MAX_MATCH; 1357 1358 #endif /* UNALIGNED_OK */ 1359 1360 if (len > best_len) { 1361 s->match_start = cur_match; 1362 best_len = len; 1363 if (len >= nice_match) break; 1364 #ifdef UNALIGNED_OK 1365 scan_end = *(ushf*)(scan+best_len-1); 1366 #else 1367 scan_end1 = scan[best_len-1]; 1368 scan_end = scan[best_len]; 1369 #endif 1370 } 1371 } while ((cur_match = prev[cur_match & wmask]) > limit 1372 && --chain_length != 0); 1373 1374 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1375 return s->lookahead; 1376 } 1377 #endif /* ASMV */ 1378 1379 #else /* FASTEST */ 1380 1381 /* --------------------------------------------------------------------------- 1382 * Optimized version for FASTEST only 1383 */ 1384 local uInt longest_match( 1385 deflate_state *s, 1386 IPos cur_match) 1387 { 1388 register Bytef *scan = s->window + s->strstart; /* current string */ 1389 register Bytef *match; /* matched string */ 1390 register int len; /* length of current match */ 1391 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1392 1393 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1394 * It is easy to get rid of this optimization if necessary. 1395 */ 1396 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1397 1398 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1399 1400 Assert(cur_match < s->strstart, "no future"); 1401 1402 match = s->window + cur_match; 1403 1404 /* Return failure if the match length is less than 2: 1405 */ 1406 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1407 1408 /* The check at best_len-1 can be removed because it will be made 1409 * again later. (This heuristic is not always a win.) 1410 * It is not necessary to compare scan[2] and match[2] since they 1411 * are always equal when the other bytes match, given that 1412 * the hash keys are equal and that HASH_BITS >= 8. 1413 */ 1414 scan += 2, match += 2; 1415 Assert(*scan == *match, "match[2]?"); 1416 1417 /* We check for insufficient lookahead only every 8th comparison; 1418 * the 256th check will be made at strstart+258. 1419 */ 1420 do { 1421 } while (*++scan == *++match && *++scan == *++match && 1422 *++scan == *++match && *++scan == *++match && 1423 *++scan == *++match && *++scan == *++match && 1424 *++scan == *++match && *++scan == *++match && 1425 scan < strend); 1426 1427 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1428 1429 len = MAX_MATCH - (int)(strend - scan); 1430 1431 if (len < MIN_MATCH) return MIN_MATCH - 1; 1432 1433 s->match_start = cur_match; 1434 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1435 } 1436 1437 #endif /* FASTEST */ 1438 1439 #ifdef ZLIB_DEBUG 1440 1441 #define EQUAL 0 1442 /* result of memcmp for equal strings */ 1443 1444 /* =========================================================================== 1445 * Check that the match at match_start is indeed a match. 1446 */ 1447 local void check_match( 1448 deflate_state *s, 1449 IPos start, 1450 IPos match, 1451 int length) 1452 { 1453 /* check that the match is indeed a match */ 1454 if (zmemcmp(s->window + match, 1455 s->window + start, length) != EQUAL) { 1456 fprintf(stderr, " start %u, match %u, length %d\n", 1457 start, match, length); 1458 do { 1459 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); 1460 } while (--length != 0); 1461 z_error("invalid match"); 1462 } 1463 if (z_verbose > 1) { 1464 fprintf(stderr,"\\[%d,%d]", start-match, length); 1465 do { putc(s->window[start++], stderr); } while (--length != 0); 1466 } 1467 } 1468 #else 1469 # define check_match(s, start, match, length) 1470 #endif /* ZLIB_DEBUG */ 1471 1472 /* =========================================================================== 1473 * Fill the window when the lookahead becomes insufficient. 1474 * Updates strstart and lookahead. 1475 * 1476 * IN assertion: lookahead < MIN_LOOKAHEAD 1477 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 1478 * At least one byte has been read, or avail_in == 0; reads are 1479 * performed for at least two bytes (required for the zip translate_eol 1480 * option -- not supported here). 1481 */ 1482 local void fill_window( 1483 deflate_state *s) 1484 { 1485 unsigned n; 1486 unsigned more; /* Amount of free space at the end of the window. */ 1487 uInt wsize = s->w_size; 1488 1489 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); 1490 1491 do { 1492 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 1493 1494 /* Deal with !@#$% 64K limit: */ 1495 if (sizeof(int) <= 2) { 1496 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 1497 more = wsize; 1498 1499 } else if (more == (unsigned)(-1)) { 1500 /* Very unlikely, but possible on 16 bit machine if 1501 * strstart == 0 && lookahead == 1 (input done a byte at time) 1502 */ 1503 more--; 1504 } 1505 } 1506 1507 /* If the window is almost full and there is insufficient lookahead, 1508 * move the upper half to the lower one to make room in the upper half. 1509 */ 1510 if (s->strstart >= wsize+MAX_DIST(s)) { 1511 1512 zmemcpy(s->window, s->window+wsize, (unsigned)wsize - more); 1513 s->match_start -= wsize; 1514 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 1515 s->block_start -= (long) wsize; 1516 slide_hash(s); 1517 more += wsize; 1518 } 1519 if (s->strm->avail_in == 0) break; 1520 1521 /* If there was no sliding: 1522 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 1523 * more == window_size - lookahead - strstart 1524 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 1525 * => more >= window_size - 2*WSIZE + 2 1526 * In the BIG_MEM or MMAP case (not yet supported), 1527 * window_size == input_size + MIN_LOOKAHEAD && 1528 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 1529 * Otherwise, window_size == 2*WSIZE so more >= 2. 1530 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 1531 */ 1532 Assert(more >= 2, "more < 2"); 1533 1534 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 1535 s->lookahead += n; 1536 1537 /* Initialize the hash value now that we have some input: */ 1538 if (s->lookahead + s->insert >= MIN_MATCH) { 1539 uInt str = s->strstart - s->insert; 1540 s->ins_h = s->window[str]; 1541 UPDATE_HASH(s, s->ins_h, s->window[str + 1]); 1542 #if MIN_MATCH != 3 1543 Call UPDATE_HASH() MIN_MATCH-3 more times 1544 #endif 1545 while (s->insert) { 1546 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 1547 #ifndef FASTEST 1548 s->prev[str & s->w_mask] = s->head[s->ins_h]; 1549 #endif 1550 s->head[s->ins_h] = (Pos)str; 1551 str++; 1552 s->insert--; 1553 if (s->lookahead + s->insert < MIN_MATCH) 1554 break; 1555 } 1556 } 1557 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 1558 * but this is not important since only literal bytes will be emitted. 1559 */ 1560 1561 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 1562 1563 /* If the WIN_INIT bytes after the end of the current data have never been 1564 * written, then zero those bytes in order to avoid memory check reports of 1565 * the use of uninitialized (or uninitialised as Julian writes) bytes by 1566 * the longest match routines. Update the high water mark for the next 1567 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 1568 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 1569 */ 1570 if (s->high_water < s->window_size) { 1571 ulg curr = s->strstart + (ulg)(s->lookahead); 1572 ulg init; 1573 1574 if (s->high_water < curr) { 1575 /* Previous high water mark below current data -- zero WIN_INIT 1576 * bytes or up to end of window, whichever is less. 1577 */ 1578 init = s->window_size - curr; 1579 if (init > WIN_INIT) 1580 init = WIN_INIT; 1581 zmemzero(s->window + curr, (unsigned)init); 1582 s->high_water = curr + init; 1583 } 1584 else if (s->high_water < (ulg)curr + WIN_INIT) { 1585 /* High water mark at or above current data, but below current data 1586 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 1587 * to end of window, whichever is less. 1588 */ 1589 init = (ulg)curr + WIN_INIT - s->high_water; 1590 if (init > s->window_size - s->high_water) 1591 init = s->window_size - s->high_water; 1592 zmemzero(s->window + s->high_water, (unsigned)init); 1593 s->high_water += init; 1594 } 1595 } 1596 1597 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1598 "not enough room for search"); 1599 } 1600 1601 /* =========================================================================== 1602 * Flush the current block, with given end-of-file flag. 1603 * IN assertion: strstart is set to the end of the current match. 1604 */ 1605 #define FLUSH_BLOCK_ONLY(s, last) { \ 1606 _tr_flush_block(s, (s->block_start >= 0L ? \ 1607 (charf *)&s->window[(unsigned)s->block_start] : \ 1608 (charf *)Z_NULL), \ 1609 (ulg)((long)s->strstart - s->block_start), \ 1610 (last)); \ 1611 s->block_start = s->strstart; \ 1612 flush_pending(s->strm); \ 1613 Tracev((stderr,"[FLUSH]")); \ 1614 } 1615 1616 /* Same but force premature exit if necessary. */ 1617 #define FLUSH_BLOCK(s, last) { \ 1618 FLUSH_BLOCK_ONLY(s, last); \ 1619 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1620 } 1621 1622 /* Maximum stored block length in deflate format (not including header). */ 1623 #define MAX_STORED 65535 1624 1625 /* Minimum of a and b. */ 1626 #define MIN(a, b) ((a) > (b) ? (b) : (a)) 1627 1628 /* =========================================================================== 1629 * Copy without compression as much as possible from the input stream, return 1630 * the current block state. 1631 * 1632 * In case deflateParams() is used to later switch to a non-zero compression 1633 * level, s->matches (otherwise unused when storing) keeps track of the number 1634 * of hash table slides to perform. If s->matches is 1, then one hash table 1635 * slide will be done when switching. If s->matches is 2, the maximum value 1636 * allowed here, then the hash table will be cleared, since two or more slides 1637 * is the same as a clear. 1638 * 1639 * deflate_stored() is written to minimize the number of times an input byte is 1640 * copied. It is most efficient with large input and output buffers, which 1641 * maximizes the opportunites to have a single copy from next_in to next_out. 1642 */ 1643 local block_state deflate_stored( 1644 deflate_state *s, 1645 int flush) 1646 { 1647 /* Smallest worthy block size when not flushing or finishing. By default 1648 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For 1649 * large input and output buffers, the stored block size will be larger. 1650 */ 1651 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size); 1652 1653 /* Copy as many min_block or larger stored blocks directly to next_out as 1654 * possible. If flushing, copy the remaining available input to next_out as 1655 * stored blocks, if there is enough space. 1656 */ 1657 unsigned len, left, have, last = 0; 1658 unsigned used = s->strm->avail_in; 1659 do { 1660 /* Set len to the maximum size block that we can copy directly with the 1661 * available input data and output space. Set left to how much of that 1662 * would be copied from what's left in the window. 1663 */ 1664 len = MAX_STORED; /* maximum deflate stored block length */ 1665 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1666 if (s->strm->avail_out < have) /* need room for header */ 1667 break; 1668 /* maximum stored block length that will fit in avail_out: */ 1669 have = s->strm->avail_out - have; 1670 left = s->strstart - s->block_start; /* bytes left in window */ 1671 if (len > (ulg)left + s->strm->avail_in) 1672 len = left + s->strm->avail_in; /* limit len to the input */ 1673 if (len > have) 1674 len = have; /* limit len to the output */ 1675 1676 /* If the stored block would be less than min_block in length, or if 1677 * unable to copy all of the available input when flushing, then try 1678 * copying to the window and the pending buffer instead. Also don't 1679 * write an empty block when flushing -- deflate() does that. 1680 */ 1681 if (len < min_block && ((len == 0 && flush != Z_FINISH) || 1682 flush == Z_NO_FLUSH || 1683 len != left + s->strm->avail_in)) 1684 break; 1685 1686 /* Make a dummy stored block in pending to get the header bytes, 1687 * including any pending bits. This also updates the debugging counts. 1688 */ 1689 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0; 1690 _tr_stored_block(s, (char *)0, 0L, last); 1691 1692 /* Replace the lengths in the dummy stored block with len. */ 1693 s->pending_buf[s->pending - 4] = len; 1694 s->pending_buf[s->pending - 3] = len >> 8; 1695 s->pending_buf[s->pending - 2] = ~len; 1696 s->pending_buf[s->pending - 1] = ~len >> 8; 1697 1698 /* Write the stored block header bytes. */ 1699 flush_pending(s->strm); 1700 1701 #ifdef ZLIB_DEBUG 1702 /* Update debugging counts for the data about to be copied. */ 1703 s->compressed_len += len << 3; 1704 s->bits_sent += len << 3; 1705 #endif 1706 1707 /* Copy uncompressed bytes from the window to next_out. */ 1708 if (left) { 1709 if (left > len) 1710 left = len; 1711 zmemcpy(s->strm->next_out, s->window + s->block_start, left); 1712 s->strm->next_out += left; 1713 s->strm->avail_out -= left; 1714 s->strm->total_out += left; 1715 s->block_start += left; 1716 len -= left; 1717 } 1718 1719 /* Copy uncompressed bytes directly from next_in to next_out, updating 1720 * the check value. 1721 */ 1722 if (len) { 1723 read_buf(s->strm, s->strm->next_out, len); 1724 s->strm->next_out += len; 1725 s->strm->avail_out -= len; 1726 s->strm->total_out += len; 1727 } 1728 } while (last == 0); 1729 1730 /* Update the sliding window with the last s->w_size bytes of the copied 1731 * data, or append all of the copied data to the existing window if less 1732 * than s->w_size bytes were copied. Also update the number of bytes to 1733 * insert in the hash tables, in the event that deflateParams() switches to 1734 * a non-zero compression level. 1735 */ 1736 used -= s->strm->avail_in; /* number of input bytes directly copied */ 1737 if (used) { 1738 /* If any input was used, then no unused input remains in the window, 1739 * therefore s->block_start == s->strstart. 1740 */ 1741 if (used >= s->w_size) { /* supplant the previous history */ 1742 s->matches = 2; /* clear hash */ 1743 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size); 1744 s->strstart = s->w_size; 1745 } 1746 else { 1747 if (s->window_size - s->strstart <= used) { 1748 /* Slide the window down. */ 1749 s->strstart -= s->w_size; 1750 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1751 if (s->matches < 2) 1752 s->matches++; /* add a pending slide_hash() */ 1753 } 1754 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used); 1755 s->strstart += used; 1756 } 1757 s->block_start = s->strstart; 1758 s->insert += MIN(used, s->w_size - s->insert); 1759 } 1760 if (s->high_water < s->strstart) 1761 s->high_water = s->strstart; 1762 1763 /* If the last block was written to next_out, then done. */ 1764 if (last) 1765 return finish_done; 1766 1767 /* If flushing and all input has been consumed, then done. */ 1768 if (flush != Z_NO_FLUSH && flush != Z_FINISH && 1769 s->strm->avail_in == 0 && (long)s->strstart == s->block_start) 1770 return block_done; 1771 1772 /* Fill the window with any remaining input. */ 1773 have = s->window_size - s->strstart - 1; 1774 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) { 1775 /* Slide the window down. */ 1776 s->block_start -= s->w_size; 1777 s->strstart -= s->w_size; 1778 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1779 if (s->matches < 2) 1780 s->matches++; /* add a pending slide_hash() */ 1781 have += s->w_size; /* more space now */ 1782 } 1783 if (have > s->strm->avail_in) 1784 have = s->strm->avail_in; 1785 if (have) { 1786 read_buf(s->strm, s->window + s->strstart, have); 1787 s->strstart += have; 1788 } 1789 if (s->high_water < s->strstart) 1790 s->high_water = s->strstart; 1791 1792 /* There was not enough avail_out to write a complete worthy or flushed 1793 * stored block to next_out. Write a stored block to pending instead, if we 1794 * have enough input for a worthy block, or if flushing and there is enough 1795 * room for the remaining input as a stored block in the pending buffer. 1796 */ 1797 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1798 /* maximum stored block length that will fit in pending: */ 1799 have = MIN(s->pending_buf_size - have, MAX_STORED); 1800 min_block = MIN(have, s->w_size); 1801 left = s->strstart - s->block_start; 1802 if (left >= min_block || 1803 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH && 1804 s->strm->avail_in == 0 && left <= have)) { 1805 len = MIN(left, have); 1806 last = flush == Z_FINISH && s->strm->avail_in == 0 && 1807 len == left ? 1 : 0; 1808 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last); 1809 s->block_start += len; 1810 flush_pending(s->strm); 1811 } 1812 1813 /* We've done all we can with the available input and output. */ 1814 return last ? finish_started : need_more; 1815 } 1816 1817 /* =========================================================================== 1818 * Compress as much as possible from the input stream, return the current 1819 * block state. 1820 * This function does not perform lazy evaluation of matches and inserts 1821 * new strings in the dictionary only for unmatched strings or for short 1822 * matches. It is used only for the fast compression options. 1823 */ 1824 local block_state deflate_fast( 1825 deflate_state *s, 1826 int flush) 1827 { 1828 IPos hash_head; /* head of the hash chain */ 1829 int bflush; /* set if current block must be flushed */ 1830 1831 for (;;) { 1832 /* Make sure that we always have enough lookahead, except 1833 * at the end of the input file. We need MAX_MATCH bytes 1834 * for the next match, plus MIN_MATCH bytes to insert the 1835 * string following the next match. 1836 */ 1837 if (s->lookahead < MIN_LOOKAHEAD) { 1838 fill_window(s); 1839 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1840 return need_more; 1841 } 1842 if (s->lookahead == 0) break; /* flush the current block */ 1843 } 1844 1845 /* Insert the string window[strstart .. strstart+2] in the 1846 * dictionary, and set hash_head to the head of the hash chain: 1847 */ 1848 hash_head = NIL; 1849 if (s->lookahead >= MIN_MATCH) { 1850 INSERT_STRING(s, s->strstart, hash_head); 1851 } 1852 1853 /* Find the longest match, discarding those <= prev_length. 1854 * At this point we have always match_length < MIN_MATCH 1855 */ 1856 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1857 /* To simplify the code, we prevent matches with the string 1858 * of window index 0 (in particular we have to avoid a match 1859 * of the string with itself at the start of the input file). 1860 */ 1861 s->match_length = longest_match (s, hash_head); 1862 /* longest_match() sets match_start */ 1863 } 1864 if (s->match_length >= MIN_MATCH) { 1865 check_match(s, s->strstart, s->match_start, s->match_length); 1866 1867 _tr_tally_dist(s, s->strstart - s->match_start, 1868 s->match_length - MIN_MATCH, bflush); 1869 1870 s->lookahead -= s->match_length; 1871 1872 /* Insert new strings in the hash table only if the match length 1873 * is not too large. This saves time but degrades compression. 1874 */ 1875 #ifndef FASTEST 1876 if (s->match_length <= s->max_insert_length && 1877 s->lookahead >= MIN_MATCH) { 1878 s->match_length--; /* string at strstart already in table */ 1879 do { 1880 s->strstart++; 1881 INSERT_STRING(s, s->strstart, hash_head); 1882 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1883 * always MIN_MATCH bytes ahead. 1884 */ 1885 } while (--s->match_length != 0); 1886 s->strstart++; 1887 } else 1888 #endif 1889 { 1890 s->strstart += s->match_length; 1891 s->match_length = 0; 1892 s->ins_h = s->window[s->strstart]; 1893 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); 1894 #if MIN_MATCH != 3 1895 Call UPDATE_HASH() MIN_MATCH-3 more times 1896 #endif 1897 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1898 * matter since it will be recomputed at next deflate call. 1899 */ 1900 } 1901 } else { 1902 /* No match, output a literal byte */ 1903 Tracevv((stderr,"%c", s->window[s->strstart])); 1904 _tr_tally_lit (s, s->window[s->strstart], bflush); 1905 s->lookahead--; 1906 s->strstart++; 1907 } 1908 if (bflush) FLUSH_BLOCK(s, 0); 1909 } 1910 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1911 if (flush == Z_FINISH) { 1912 FLUSH_BLOCK(s, 1); 1913 return finish_done; 1914 } 1915 if (s->last_lit) 1916 FLUSH_BLOCK(s, 0); 1917 return block_done; 1918 } 1919 1920 #ifndef FASTEST 1921 /* =========================================================================== 1922 * Same as above, but achieves better compression. We use a lazy 1923 * evaluation for matches: a match is finally adopted only if there is 1924 * no better match at the next window position. 1925 */ 1926 local block_state deflate_slow( 1927 deflate_state *s, 1928 int flush) 1929 { 1930 IPos hash_head; /* head of hash chain */ 1931 int bflush; /* set if current block must be flushed */ 1932 1933 /* Process the input block. */ 1934 for (;;) { 1935 /* Make sure that we always have enough lookahead, except 1936 * at the end of the input file. We need MAX_MATCH bytes 1937 * for the next match, plus MIN_MATCH bytes to insert the 1938 * string following the next match. 1939 */ 1940 if (s->lookahead < MIN_LOOKAHEAD) { 1941 fill_window(s); 1942 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1943 return need_more; 1944 } 1945 if (s->lookahead == 0) break; /* flush the current block */ 1946 } 1947 1948 /* Insert the string window[strstart .. strstart+2] in the 1949 * dictionary, and set hash_head to the head of the hash chain: 1950 */ 1951 hash_head = NIL; 1952 if (s->lookahead >= MIN_MATCH) { 1953 INSERT_STRING(s, s->strstart, hash_head); 1954 } 1955 1956 /* Find the longest match, discarding those <= prev_length. 1957 */ 1958 s->prev_length = s->match_length, s->prev_match = s->match_start; 1959 s->match_length = MIN_MATCH-1; 1960 1961 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1962 s->strstart - hash_head <= MAX_DIST(s)) { 1963 /* To simplify the code, we prevent matches with the string 1964 * of window index 0 (in particular we have to avoid a match 1965 * of the string with itself at the start of the input file). 1966 */ 1967 s->match_length = longest_match (s, hash_head); 1968 /* longest_match() sets match_start */ 1969 1970 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1971 #if TOO_FAR <= 32767 1972 || (s->match_length == MIN_MATCH && 1973 s->strstart - s->match_start > TOO_FAR) 1974 #endif 1975 )) { 1976 1977 /* If prev_match is also MIN_MATCH, match_start is garbage 1978 * but we will ignore the current match anyway. 1979 */ 1980 s->match_length = MIN_MATCH-1; 1981 } 1982 } 1983 /* If there was a match at the previous step and the current 1984 * match is not better, output the previous match: 1985 */ 1986 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1987 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1988 /* Do not insert strings in hash table beyond this. */ 1989 1990 check_match(s, s->strstart-1, s->prev_match, s->prev_length); 1991 1992 _tr_tally_dist(s, s->strstart -1 - s->prev_match, 1993 s->prev_length - MIN_MATCH, bflush); 1994 1995 /* Insert in hash table all strings up to the end of the match. 1996 * strstart-1 and strstart are already inserted. If there is not 1997 * enough lookahead, the last two strings are not inserted in 1998 * the hash table. 1999 */ 2000 s->lookahead -= s->prev_length-1; 2001 s->prev_length -= 2; 2002 do { 2003 if (++s->strstart <= max_insert) { 2004 INSERT_STRING(s, s->strstart, hash_head); 2005 } 2006 } while (--s->prev_length != 0); 2007 s->match_available = 0; 2008 s->match_length = MIN_MATCH-1; 2009 s->strstart++; 2010 2011 if (bflush) FLUSH_BLOCK(s, 0); 2012 2013 } else if (s->match_available) { 2014 /* If there was no match at the previous position, output a 2015 * single literal. If there was a match but the current match 2016 * is longer, truncate the previous match to a single literal. 2017 */ 2018 Tracevv((stderr,"%c", s->window[s->strstart-1])); 2019 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 2020 if (bflush) { 2021 FLUSH_BLOCK_ONLY(s, 0); 2022 } 2023 s->strstart++; 2024 s->lookahead--; 2025 if (s->strm->avail_out == 0) return need_more; 2026 } else { 2027 /* There is no previous match to compare with, wait for 2028 * the next step to decide. 2029 */ 2030 s->match_available = 1; 2031 s->strstart++; 2032 s->lookahead--; 2033 } 2034 } 2035 Assert (flush != Z_NO_FLUSH, "no flush?"); 2036 if (s->match_available) { 2037 Tracevv((stderr,"%c", s->window[s->strstart-1])); 2038 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 2039 s->match_available = 0; 2040 } 2041 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 2042 if (flush == Z_FINISH) { 2043 FLUSH_BLOCK(s, 1); 2044 return finish_done; 2045 } 2046 if (s->last_lit) 2047 FLUSH_BLOCK(s, 0); 2048 return block_done; 2049 } 2050 #endif /* FASTEST */ 2051 2052 /* =========================================================================== 2053 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 2054 * one. Do not maintain a hash table. (It will be regenerated if this run of 2055 * deflate switches away from Z_RLE.) 2056 */ 2057 local block_state deflate_rle( 2058 deflate_state *s, 2059 int flush) 2060 { 2061 int bflush; /* set if current block must be flushed */ 2062 uInt prev; /* byte at distance one to match */ 2063 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 2064 2065 for (;;) { 2066 /* Make sure that we always have enough lookahead, except 2067 * at the end of the input file. We need MAX_MATCH bytes 2068 * for the longest run, plus one for the unrolled loop. 2069 */ 2070 if (s->lookahead <= MAX_MATCH) { 2071 fill_window(s); 2072 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 2073 return need_more; 2074 } 2075 if (s->lookahead == 0) break; /* flush the current block */ 2076 } 2077 2078 /* See how many times the previous byte repeats */ 2079 s->match_length = 0; 2080 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 2081 scan = s->window + s->strstart - 1; 2082 prev = *scan; 2083 if (prev == *++scan && prev == *++scan && prev == *++scan) { 2084 strend = s->window + s->strstart + MAX_MATCH; 2085 do { 2086 } while (prev == *++scan && prev == *++scan && 2087 prev == *++scan && prev == *++scan && 2088 prev == *++scan && prev == *++scan && 2089 prev == *++scan && prev == *++scan && 2090 scan < strend); 2091 s->match_length = MAX_MATCH - (uInt)(strend - scan); 2092 if (s->match_length > s->lookahead) 2093 s->match_length = s->lookahead; 2094 } 2095 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan"); 2096 } 2097 2098 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 2099 if (s->match_length >= MIN_MATCH) { 2100 check_match(s, s->strstart, s->strstart - 1, s->match_length); 2101 2102 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 2103 2104 s->lookahead -= s->match_length; 2105 s->strstart += s->match_length; 2106 s->match_length = 0; 2107 } else { 2108 /* No match, output a literal byte */ 2109 Tracevv((stderr,"%c", s->window[s->strstart])); 2110 _tr_tally_lit (s, s->window[s->strstart], bflush); 2111 s->lookahead--; 2112 s->strstart++; 2113 } 2114 if (bflush) FLUSH_BLOCK(s, 0); 2115 } 2116 s->insert = 0; 2117 if (flush == Z_FINISH) { 2118 FLUSH_BLOCK(s, 1); 2119 return finish_done; 2120 } 2121 if (s->last_lit) 2122 FLUSH_BLOCK(s, 0); 2123 return block_done; 2124 } 2125 2126 /* =========================================================================== 2127 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 2128 * (It will be regenerated if this run of deflate switches away from Huffman.) 2129 */ 2130 local block_state deflate_huff( 2131 deflate_state *s, 2132 int flush) 2133 { 2134 int bflush; /* set if current block must be flushed */ 2135 2136 for (;;) { 2137 /* Make sure that we have a literal to write. */ 2138 if (s->lookahead == 0) { 2139 fill_window(s); 2140 if (s->lookahead == 0) { 2141 if (flush == Z_NO_FLUSH) 2142 return need_more; 2143 break; /* flush the current block */ 2144 } 2145 } 2146 2147 /* Output a literal byte */ 2148 s->match_length = 0; 2149 Tracevv((stderr,"%c", s->window[s->strstart])); 2150 _tr_tally_lit (s, s->window[s->strstart], bflush); 2151 s->lookahead--; 2152 s->strstart++; 2153 if (bflush) FLUSH_BLOCK(s, 0); 2154 } 2155 s->insert = 0; 2156 if (flush == Z_FINISH) { 2157 FLUSH_BLOCK(s, 1); 2158 return finish_done; 2159 } 2160 if (s->last_lit) 2161 FLUSH_BLOCK(s, 0); 2162 return block_done; 2163 } 2164