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 do { \ 194 s->head[s->hash_size-1] = NIL; \ 195 zmemzero((Bytef *)s->head, \ 196 (unsigned)(s->hash_size-1)*sizeof(*s->head)); \ 197 } while (0) 198 199 /* =========================================================================== 200 * Slide the hash table when sliding the window down (could be avoided with 32 201 * bit values at the expense of memory usage). We slide even when level == 0 to 202 * keep the hash table consistent if we switch back to level > 0 later. 203 */ 204 local void slide_hash( 205 deflate_state *s) 206 { 207 unsigned n, m; 208 Posf *p; 209 uInt wsize = s->w_size; 210 211 n = s->hash_size; 212 p = &s->head[n]; 213 do { 214 m = *--p; 215 *p = (Pos)(m >= wsize ? m - wsize : NIL); 216 } while (--n); 217 n = wsize; 218 #ifndef FASTEST 219 p = &s->prev[n]; 220 do { 221 m = *--p; 222 *p = (Pos)(m >= wsize ? m - wsize : NIL); 223 /* If n is not on any hash chain, prev[n] is garbage but 224 * its value will never be used. 225 */ 226 } while (--n); 227 #endif 228 } 229 230 /* ========================================================================= */ 231 int ZEXPORT deflateInit_( 232 z_streamp strm, 233 int level, 234 const char *version, 235 int stream_size) 236 { 237 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, 238 Z_DEFAULT_STRATEGY, version, stream_size); 239 /* To do: ignore strm->next_in if we use it as window */ 240 } 241 242 /* ========================================================================= */ 243 int ZEXPORT deflateInit2_( 244 z_streamp strm, 245 int level, 246 int method, 247 int windowBits, 248 int memLevel, 249 int strategy, 250 const char *version, 251 int stream_size) 252 { 253 deflate_state *s; 254 int wrap = 1; 255 static const char my_version[] = ZLIB_VERSION; 256 257 ushf *overlay; 258 /* We overlay pending_buf and d_buf+l_buf. This works since the average 259 * output size for (length,distance) codes is <= 24 bits. 260 */ 261 262 if (version == Z_NULL || version[0] != my_version[0] || 263 stream_size != sizeof(z_stream)) { 264 return Z_VERSION_ERROR; 265 } 266 if (strm == Z_NULL) return Z_STREAM_ERROR; 267 268 strm->msg = Z_NULL; 269 if (strm->zalloc == (alloc_func)0) { 270 #ifdef Z_SOLO 271 return Z_STREAM_ERROR; 272 #else 273 strm->zalloc = zcalloc; 274 strm->opaque = (voidpf)0; 275 #endif 276 } 277 if (strm->zfree == (free_func)0) 278 #ifdef Z_SOLO 279 return Z_STREAM_ERROR; 280 #else 281 strm->zfree = zcfree; 282 #endif 283 284 #ifdef FASTEST 285 if (level != 0) level = 1; 286 #else 287 if (level == Z_DEFAULT_COMPRESSION) level = 6; 288 #endif 289 290 if (windowBits < 0) { /* suppress zlib wrapper */ 291 wrap = 0; 292 windowBits = -windowBits; 293 } 294 #ifdef GZIP 295 else if (windowBits > 15) { 296 wrap = 2; /* write gzip wrapper instead */ 297 windowBits -= 16; 298 } 299 #endif 300 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 301 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 302 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) { 303 return Z_STREAM_ERROR; 304 } 305 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 306 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 307 if (s == Z_NULL) return Z_MEM_ERROR; 308 strm->state = (struct internal_state FAR *)s; 309 s->strm = strm; 310 s->status = INIT_STATE; /* to pass state test in deflateReset() */ 311 312 s->wrap = wrap; 313 s->gzhead = Z_NULL; 314 s->w_bits = (uInt)windowBits; 315 s->w_size = 1 << s->w_bits; 316 s->w_mask = s->w_size - 1; 317 318 s->hash_bits = (uInt)memLevel + 7; 319 s->hash_size = 1 << s->hash_bits; 320 s->hash_mask = s->hash_size - 1; 321 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); 322 323 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 324 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 325 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 326 327 s->high_water = 0; /* nothing written to s->window yet */ 328 329 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 330 331 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); 332 s->pending_buf = (uchf *) overlay; 333 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); 334 335 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 336 s->pending_buf == Z_NULL) { 337 s->status = FINISH_STATE; 338 strm->msg = ERR_MSG(Z_MEM_ERROR); 339 deflateEnd (strm); 340 return Z_MEM_ERROR; 341 } 342 s->d_buf = overlay + s->lit_bufsize/sizeof(ush); 343 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; 344 345 s->level = level; 346 s->strategy = strategy; 347 s->method = (Byte)method; 348 349 return deflateReset(strm); 350 } 351 352 /* ========================================================================= 353 * Check for a valid deflate stream state. Return 0 if ok, 1 if not. 354 */ 355 local int deflateStateCheck ( 356 z_streamp strm) 357 { 358 deflate_state *s; 359 if (strm == Z_NULL || 360 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) 361 return 1; 362 s = strm->state; 363 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE && 364 #ifdef GZIP 365 s->status != GZIP_STATE && 366 #endif 367 s->status != EXTRA_STATE && 368 s->status != NAME_STATE && 369 s->status != COMMENT_STATE && 370 s->status != HCRC_STATE && 371 s->status != BUSY_STATE && 372 s->status != FINISH_STATE)) 373 return 1; 374 return 0; 375 } 376 377 /* ========================================================================= */ 378 int ZEXPORT deflateSetDictionary ( 379 z_streamp strm, 380 const Bytef *dictionary, 381 uInt dictLength) 382 { 383 deflate_state *s; 384 uInt str, n; 385 int wrap; 386 unsigned avail; 387 z_const unsigned char *next; 388 389 if (deflateStateCheck(strm) || dictionary == Z_NULL) 390 return Z_STREAM_ERROR; 391 s = strm->state; 392 wrap = s->wrap; 393 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) 394 return Z_STREAM_ERROR; 395 396 /* when using zlib wrappers, compute Adler-32 for provided dictionary */ 397 if (wrap == 1) 398 strm->adler = adler32(strm->adler, dictionary, dictLength); 399 s->wrap = 0; /* avoid computing Adler-32 in read_buf */ 400 401 /* if dictionary would fill window, just replace the history */ 402 if (dictLength >= s->w_size) { 403 if (wrap == 0) { /* already empty otherwise */ 404 CLEAR_HASH(s); 405 s->strstart = 0; 406 s->block_start = 0L; 407 s->insert = 0; 408 } 409 dictionary += dictLength - s->w_size; /* use the tail */ 410 dictLength = s->w_size; 411 } 412 413 /* insert dictionary into window and hash */ 414 avail = strm->avail_in; 415 next = strm->next_in; 416 strm->avail_in = dictLength; 417 strm->next_in = (z_const Bytef *)dictionary; 418 fill_window(s); 419 while (s->lookahead >= MIN_MATCH) { 420 str = s->strstart; 421 n = s->lookahead - (MIN_MATCH-1); 422 do { 423 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 424 #ifndef FASTEST 425 s->prev[str & s->w_mask] = s->head[s->ins_h]; 426 #endif 427 s->head[s->ins_h] = (Pos)str; 428 str++; 429 } while (--n); 430 s->strstart = str; 431 s->lookahead = MIN_MATCH-1; 432 fill_window(s); 433 } 434 s->strstart += s->lookahead; 435 s->block_start = (long)s->strstart; 436 s->insert = s->lookahead; 437 s->lookahead = 0; 438 s->match_length = s->prev_length = MIN_MATCH-1; 439 s->match_available = 0; 440 strm->next_in = next; 441 strm->avail_in = avail; 442 s->wrap = wrap; 443 return Z_OK; 444 } 445 446 /* ========================================================================= */ 447 int ZEXPORT deflateGetDictionary ( 448 z_streamp strm, 449 Bytef *dictionary, 450 uInt *dictLength) 451 { 452 deflate_state *s; 453 uInt len; 454 455 if (deflateStateCheck(strm)) 456 return Z_STREAM_ERROR; 457 s = strm->state; 458 len = s->strstart + s->lookahead; 459 if (len > s->w_size) 460 len = s->w_size; 461 if (dictionary != Z_NULL && len) 462 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len); 463 if (dictLength != Z_NULL) 464 *dictLength = len; 465 return Z_OK; 466 } 467 468 /* ========================================================================= */ 469 int ZEXPORT deflateResetKeep ( 470 z_streamp strm) 471 { 472 deflate_state *s; 473 474 if (deflateStateCheck(strm)) { 475 return Z_STREAM_ERROR; 476 } 477 478 strm->total_in = strm->total_out = 0; 479 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 480 strm->data_type = Z_UNKNOWN; 481 482 s = (deflate_state *)strm->state; 483 s->pending = 0; 484 s->pending_out = s->pending_buf; 485 486 if (s->wrap < 0) { 487 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 488 } 489 s->status = 490 #ifdef GZIP 491 s->wrap == 2 ? GZIP_STATE : 492 #endif 493 s->wrap ? INIT_STATE : BUSY_STATE; 494 strm->adler = 495 #ifdef GZIP 496 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 497 #endif 498 adler32(0L, Z_NULL, 0); 499 s->last_flush = Z_NO_FLUSH; 500 501 _tr_init(s); 502 503 return Z_OK; 504 } 505 506 /* ========================================================================= */ 507 int ZEXPORT deflateReset ( 508 z_streamp strm) 509 { 510 int ret; 511 512 ret = deflateResetKeep(strm); 513 if (ret == Z_OK) 514 lm_init(strm->state); 515 return ret; 516 } 517 518 /* ========================================================================= */ 519 int ZEXPORT deflateSetHeader ( 520 z_streamp strm, 521 gz_headerp head) 522 { 523 if (deflateStateCheck(strm) || strm->state->wrap != 2) 524 return Z_STREAM_ERROR; 525 strm->state->gzhead = head; 526 return Z_OK; 527 } 528 529 /* ========================================================================= */ 530 int ZEXPORT deflatePending ( 531 z_streamp strm, 532 unsigned *pending, 533 int *bits) 534 { 535 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 536 if (pending != Z_NULL) 537 *pending = strm->state->pending; 538 if (bits != Z_NULL) 539 *bits = strm->state->bi_valid; 540 return Z_OK; 541 } 542 543 /* ========================================================================= */ 544 int ZEXPORT deflatePrime ( 545 z_streamp strm, 546 int bits, 547 int value) 548 { 549 deflate_state *s; 550 int put; 551 552 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 553 s = strm->state; 554 if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3)) 555 return Z_BUF_ERROR; 556 do { 557 put = Buf_size - s->bi_valid; 558 if (put > bits) 559 put = bits; 560 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); 561 s->bi_valid += put; 562 _tr_flush_bits(s); 563 value >>= put; 564 bits -= put; 565 } while (bits); 566 return Z_OK; 567 } 568 569 /* ========================================================================= */ 570 int ZEXPORT deflateParams( 571 z_streamp strm, 572 int level, 573 int strategy) 574 { 575 deflate_state *s; 576 compress_func func; 577 578 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 579 s = strm->state; 580 581 #ifdef FASTEST 582 if (level != 0) level = 1; 583 #else 584 if (level == Z_DEFAULT_COMPRESSION) level = 6; 585 #endif 586 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 587 return Z_STREAM_ERROR; 588 } 589 func = configuration_table[s->level].func; 590 591 if ((strategy != s->strategy || func != configuration_table[level].func) && 592 s->high_water) { 593 /* Flush the last buffer: */ 594 int err = deflate(strm, Z_BLOCK); 595 if (err == Z_STREAM_ERROR) 596 return err; 597 if (strm->avail_out == 0) 598 return Z_BUF_ERROR; 599 } 600 if (s->level != level) { 601 if (s->level == 0 && s->matches != 0) { 602 if (s->matches == 1) 603 slide_hash(s); 604 else 605 CLEAR_HASH(s); 606 s->matches = 0; 607 } 608 s->level = level; 609 s->max_lazy_match = configuration_table[level].max_lazy; 610 s->good_match = configuration_table[level].good_length; 611 s->nice_match = configuration_table[level].nice_length; 612 s->max_chain_length = configuration_table[level].max_chain; 613 } 614 s->strategy = strategy; 615 return Z_OK; 616 } 617 618 /* ========================================================================= */ 619 int ZEXPORT deflateTune( 620 z_streamp strm, 621 int good_length, 622 int max_lazy, 623 int nice_length, 624 int max_chain) 625 { 626 deflate_state *s; 627 628 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 629 s = strm->state; 630 s->good_match = (uInt)good_length; 631 s->max_lazy_match = (uInt)max_lazy; 632 s->nice_match = nice_length; 633 s->max_chain_length = (uInt)max_chain; 634 return Z_OK; 635 } 636 637 /* ========================================================================= 638 * For the default windowBits of 15 and memLevel of 8, this function returns 639 * a close to exact, as well as small, upper bound on the compressed size. 640 * They are coded as constants here for a reason--if the #define's are 641 * changed, then this function needs to be changed as well. The return 642 * value for 15 and 8 only works for those exact settings. 643 * 644 * For any setting other than those defaults for windowBits and memLevel, 645 * the value returned is a conservative worst case for the maximum expansion 646 * resulting from using fixed blocks instead of stored blocks, which deflate 647 * can emit on compressed data for some combinations of the parameters. 648 * 649 * This function could be more sophisticated to provide closer upper bounds for 650 * every combination of windowBits and memLevel. But even the conservative 651 * upper bound of about 14% expansion does not seem onerous for output buffer 652 * allocation. 653 */ 654 uLong ZEXPORT deflateBound( 655 z_streamp strm, 656 uLong sourceLen) 657 { 658 deflate_state *s; 659 uLong complen, wraplen; 660 661 /* conservative upper bound for compressed data */ 662 complen = sourceLen + 663 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5; 664 665 /* if can't get parameters, return conservative bound plus zlib wrapper */ 666 if (deflateStateCheck(strm)) 667 return complen + 6; 668 669 /* compute wrapper length */ 670 s = strm->state; 671 switch (s->wrap) { 672 case 0: /* raw deflate */ 673 wraplen = 0; 674 break; 675 case 1: /* zlib wrapper */ 676 wraplen = 6 + (s->strstart ? 4 : 0); 677 break; 678 #ifdef GZIP 679 case 2: /* gzip wrapper */ 680 wraplen = 18; 681 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 682 Bytef *str; 683 if (s->gzhead->extra != Z_NULL) 684 wraplen += 2 + s->gzhead->extra_len; 685 str = s->gzhead->name; 686 if (str != Z_NULL) 687 do { 688 wraplen++; 689 } while (*str++); 690 str = s->gzhead->comment; 691 if (str != Z_NULL) 692 do { 693 wraplen++; 694 } while (*str++); 695 if (s->gzhead->hcrc) 696 wraplen += 2; 697 } 698 break; 699 #endif 700 default: /* for compiler happiness */ 701 wraplen = 6; 702 } 703 704 /* if not default parameters, return conservative bound */ 705 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 706 return complen + wraplen; 707 708 /* default settings: return tight bound for that case */ 709 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 710 (sourceLen >> 25) + 13 - 6 + wraplen; 711 } 712 713 /* ========================================================================= 714 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 715 * IN assertion: the stream state is correct and there is enough room in 716 * pending_buf. 717 */ 718 local void putShortMSB ( 719 deflate_state *s, 720 uInt b) 721 { 722 put_byte(s, (Byte)(b >> 8)); 723 put_byte(s, (Byte)(b & 0xff)); 724 } 725 726 /* ========================================================================= 727 * Flush as much pending output as possible. All deflate() output, except for 728 * some deflate_stored() output, goes through this function so some 729 * applications may wish to modify it to avoid allocating a large 730 * strm->next_out buffer and copying into it. (See also read_buf()). 731 */ 732 local void flush_pending( 733 z_streamp strm) 734 { 735 unsigned len; 736 deflate_state *s = strm->state; 737 738 _tr_flush_bits(s); 739 len = s->pending; 740 if (len > strm->avail_out) len = strm->avail_out; 741 if (len == 0) return; 742 743 zmemcpy(strm->next_out, s->pending_out, len); 744 strm->next_out += len; 745 s->pending_out += len; 746 strm->total_out += len; 747 strm->avail_out -= len; 748 s->pending -= len; 749 if (s->pending == 0) { 750 s->pending_out = s->pending_buf; 751 } 752 } 753 754 /* =========================================================================== 755 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1]. 756 */ 757 #define HCRC_UPDATE(beg) \ 758 do { \ 759 if (s->gzhead->hcrc && s->pending > (beg)) \ 760 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \ 761 s->pending - (beg)); \ 762 } while (0) 763 764 /* ========================================================================= */ 765 int ZEXPORT deflate ( 766 z_streamp strm, 767 int flush) 768 { 769 int old_flush; /* value of flush param for previous deflate call */ 770 deflate_state *s; 771 772 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { 773 return Z_STREAM_ERROR; 774 } 775 s = strm->state; 776 777 if (strm->next_out == Z_NULL || 778 (strm->avail_in != 0 && strm->next_in == Z_NULL) || 779 (s->status == FINISH_STATE && flush != Z_FINISH)) { 780 ERR_RETURN(strm, Z_STREAM_ERROR); 781 } 782 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 783 784 old_flush = s->last_flush; 785 s->last_flush = flush; 786 787 /* Flush as much pending output as possible */ 788 if (s->pending != 0) { 789 flush_pending(strm); 790 if (strm->avail_out == 0) { 791 /* Since avail_out is 0, deflate will be called again with 792 * more output space, but possibly with both pending and 793 * avail_in equal to zero. There won't be anything to do, 794 * but this is not an error situation so make sure we 795 * return OK instead of BUF_ERROR at next call of deflate: 796 */ 797 s->last_flush = -1; 798 return Z_OK; 799 } 800 801 /* Make sure there is something to do and avoid duplicate consecutive 802 * flushes. For repeated and useless calls with Z_FINISH, we keep 803 * returning Z_STREAM_END instead of Z_BUF_ERROR. 804 */ 805 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 806 flush != Z_FINISH) { 807 ERR_RETURN(strm, Z_BUF_ERROR); 808 } 809 810 /* User must not provide more input after the first FINISH: */ 811 if (s->status == FINISH_STATE && strm->avail_in != 0) { 812 ERR_RETURN(strm, Z_BUF_ERROR); 813 } 814 815 /* Write the header */ 816 if (s->status == INIT_STATE) { 817 /* zlib header */ 818 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; 819 uInt level_flags; 820 821 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 822 level_flags = 0; 823 else if (s->level < 6) 824 level_flags = 1; 825 else if (s->level == 6) 826 level_flags = 2; 827 else 828 level_flags = 3; 829 header |= (level_flags << 6); 830 if (s->strstart != 0) header |= PRESET_DICT; 831 header += 31 - (header % 31); 832 833 putShortMSB(s, header); 834 835 /* Save the adler32 of the preset dictionary: */ 836 if (s->strstart != 0) { 837 putShortMSB(s, (uInt)(strm->adler >> 16)); 838 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 839 } 840 strm->adler = adler32(0L, Z_NULL, 0); 841 s->status = BUSY_STATE; 842 843 /* Compression must start with an empty pending buffer */ 844 flush_pending(strm); 845 if (s->pending != 0) { 846 s->last_flush = -1; 847 return Z_OK; 848 } 849 } 850 #ifdef GZIP 851 if (s->status == GZIP_STATE) { 852 /* gzip header */ 853 strm->adler = crc32(0L, Z_NULL, 0); 854 put_byte(s, 31); 855 put_byte(s, 139); 856 put_byte(s, 8); 857 if (s->gzhead == Z_NULL) { 858 put_byte(s, 0); 859 put_byte(s, 0); 860 put_byte(s, 0); 861 put_byte(s, 0); 862 put_byte(s, 0); 863 put_byte(s, s->level == 9 ? 2 : 864 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 865 4 : 0)); 866 put_byte(s, OS_CODE); 867 s->status = BUSY_STATE; 868 869 /* Compression must start with an empty pending buffer */ 870 flush_pending(strm); 871 if (s->pending != 0) { 872 s->last_flush = -1; 873 return Z_OK; 874 } 875 } 876 else { 877 put_byte(s, (s->gzhead->text ? 1 : 0) + 878 (s->gzhead->hcrc ? 2 : 0) + 879 (s->gzhead->extra == Z_NULL ? 0 : 4) + 880 (s->gzhead->name == Z_NULL ? 0 : 8) + 881 (s->gzhead->comment == Z_NULL ? 0 : 16) 882 ); 883 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 884 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 885 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 886 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 887 put_byte(s, s->level == 9 ? 2 : 888 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 889 4 : 0)); 890 put_byte(s, s->gzhead->os & 0xff); 891 if (s->gzhead->extra != Z_NULL) { 892 put_byte(s, s->gzhead->extra_len & 0xff); 893 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 894 } 895 if (s->gzhead->hcrc) 896 strm->adler = crc32(strm->adler, s->pending_buf, 897 s->pending); 898 s->gzindex = 0; 899 s->status = EXTRA_STATE; 900 } 901 } 902 if (s->status == EXTRA_STATE) { 903 if (s->gzhead->extra != Z_NULL) { 904 ulg beg = s->pending; /* start of bytes to update crc */ 905 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex; 906 while (s->pending + left > s->pending_buf_size) { 907 uInt copy = s->pending_buf_size - s->pending; 908 zmemcpy(s->pending_buf + s->pending, 909 s->gzhead->extra + s->gzindex, copy); 910 s->pending = s->pending_buf_size; 911 HCRC_UPDATE(beg); 912 s->gzindex += copy; 913 flush_pending(strm); 914 if (s->pending != 0) { 915 s->last_flush = -1; 916 return Z_OK; 917 } 918 beg = 0; 919 left -= copy; 920 } 921 zmemcpy(s->pending_buf + s->pending, 922 s->gzhead->extra + s->gzindex, left); 923 s->pending += left; 924 HCRC_UPDATE(beg); 925 s->gzindex = 0; 926 } 927 s->status = NAME_STATE; 928 } 929 if (s->status == NAME_STATE) { 930 if (s->gzhead->name != Z_NULL) { 931 ulg beg = s->pending; /* start of bytes to update crc */ 932 int val; 933 do { 934 if (s->pending == s->pending_buf_size) { 935 HCRC_UPDATE(beg); 936 flush_pending(strm); 937 if (s->pending != 0) { 938 s->last_flush = -1; 939 return Z_OK; 940 } 941 beg = 0; 942 } 943 val = s->gzhead->name[s->gzindex++]; 944 put_byte(s, val); 945 } while (val != 0); 946 HCRC_UPDATE(beg); 947 s->gzindex = 0; 948 } 949 s->status = COMMENT_STATE; 950 } 951 if (s->status == COMMENT_STATE) { 952 if (s->gzhead->comment != Z_NULL) { 953 ulg beg = s->pending; /* start of bytes to update crc */ 954 int val; 955 do { 956 if (s->pending == s->pending_buf_size) { 957 HCRC_UPDATE(beg); 958 flush_pending(strm); 959 if (s->pending != 0) { 960 s->last_flush = -1; 961 return Z_OK; 962 } 963 beg = 0; 964 } 965 val = s->gzhead->comment[s->gzindex++]; 966 put_byte(s, val); 967 } while (val != 0); 968 HCRC_UPDATE(beg); 969 } 970 s->status = HCRC_STATE; 971 } 972 if (s->status == HCRC_STATE) { 973 if (s->gzhead->hcrc) { 974 if (s->pending + 2 > s->pending_buf_size) { 975 flush_pending(strm); 976 if (s->pending != 0) { 977 s->last_flush = -1; 978 return Z_OK; 979 } 980 } 981 put_byte(s, (Byte)(strm->adler & 0xff)); 982 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 983 strm->adler = crc32(0L, Z_NULL, 0); 984 } 985 s->status = BUSY_STATE; 986 987 /* Compression must start with an empty pending buffer */ 988 flush_pending(strm); 989 if (s->pending != 0) { 990 s->last_flush = -1; 991 return Z_OK; 992 } 993 } 994 #endif 995 996 /* Start a new block or continue the current one. 997 */ 998 if (strm->avail_in != 0 || s->lookahead != 0 || 999 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 1000 block_state bstate; 1001 1002 bstate = s->level == 0 ? deflate_stored(s, flush) : 1003 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 1004 s->strategy == Z_RLE ? deflate_rle(s, flush) : 1005 (*(configuration_table[s->level].func))(s, flush); 1006 1007 if (bstate == finish_started || bstate == finish_done) { 1008 s->status = FINISH_STATE; 1009 } 1010 if (bstate == need_more || bstate == finish_started) { 1011 if (strm->avail_out == 0) { 1012 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 1013 } 1014 return Z_OK; 1015 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 1016 * of deflate should use the same flush parameter to make sure 1017 * that the flush is complete. So we don't have to output an 1018 * empty block here, this will be done at next call. This also 1019 * ensures that for a very small output buffer, we emit at most 1020 * one empty block. 1021 */ 1022 } 1023 if (bstate == block_done) { 1024 if (flush == Z_PARTIAL_FLUSH) { 1025 _tr_align(s); 1026 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 1027 _tr_stored_block(s, (char*)0, 0L, 0); 1028 /* For a full flush, this empty block will be recognized 1029 * as a special marker by inflate_sync(). 1030 */ 1031 if (flush == Z_FULL_FLUSH) { 1032 CLEAR_HASH(s); /* forget history */ 1033 if (s->lookahead == 0) { 1034 s->strstart = 0; 1035 s->block_start = 0L; 1036 s->insert = 0; 1037 } 1038 } 1039 } 1040 flush_pending(strm); 1041 if (strm->avail_out == 0) { 1042 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 1043 return Z_OK; 1044 } 1045 } 1046 } 1047 1048 if (flush != Z_FINISH) return Z_OK; 1049 if (s->wrap <= 0) return Z_STREAM_END; 1050 1051 /* Write the trailer */ 1052 #ifdef GZIP 1053 if (s->wrap == 2) { 1054 put_byte(s, (Byte)(strm->adler & 0xff)); 1055 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1056 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 1057 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 1058 put_byte(s, (Byte)(strm->total_in & 0xff)); 1059 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 1060 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 1061 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 1062 } 1063 else 1064 #endif 1065 { 1066 putShortMSB(s, (uInt)(strm->adler >> 16)); 1067 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1068 } 1069 flush_pending(strm); 1070 /* If avail_out is zero, the application will call deflate again 1071 * to flush the rest. 1072 */ 1073 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 1074 return s->pending != 0 ? Z_OK : Z_STREAM_END; 1075 } 1076 1077 /* ========================================================================= */ 1078 int ZEXPORT deflateEnd ( 1079 z_streamp strm) 1080 { 1081 int status; 1082 1083 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 1084 1085 status = strm->state->status; 1086 1087 /* Deallocate in reverse order of allocations: */ 1088 TRY_FREE(strm, strm->state->pending_buf); 1089 TRY_FREE(strm, strm->state->head); 1090 TRY_FREE(strm, strm->state->prev); 1091 TRY_FREE(strm, strm->state->window); 1092 1093 ZFREE(strm, strm->state); 1094 strm->state = Z_NULL; 1095 1096 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1097 } 1098 1099 /* ========================================================================= 1100 * Copy the source state to the destination state. 1101 * To simplify the source, this is not supported for 16-bit MSDOS (which 1102 * doesn't have enough memory anyway to duplicate compression states). 1103 */ 1104 int ZEXPORT deflateCopy ( 1105 z_streamp dest, 1106 z_streamp source) 1107 { 1108 #ifdef MAXSEG_64K 1109 return Z_STREAM_ERROR; 1110 #else 1111 deflate_state *ds; 1112 deflate_state *ss; 1113 ushf *overlay; 1114 1115 1116 if (deflateStateCheck(source) || dest == Z_NULL) { 1117 return Z_STREAM_ERROR; 1118 } 1119 1120 ss = source->state; 1121 1122 zmemcpy((Bytef*)dest, (Bytef*)source, sizeof(z_stream)); 1123 1124 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1125 if (ds == Z_NULL) return Z_MEM_ERROR; 1126 dest->state = (struct internal_state FAR *) ds; 1127 zmemcpy((Bytef*)ds, (Bytef*)ss, sizeof(deflate_state)); 1128 ds->strm = dest; 1129 1130 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1131 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1132 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1133 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); 1134 ds->pending_buf = (uchf *) overlay; 1135 1136 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1137 ds->pending_buf == Z_NULL) { 1138 deflateEnd (dest); 1139 return Z_MEM_ERROR; 1140 } 1141 /* following zmemcpy do not work for 16-bit MSDOS */ 1142 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1143 zmemcpy((Bytef*)ds->prev, (Bytef*)ss->prev, ds->w_size * sizeof(Pos)); 1144 zmemcpy((Bytef*)ds->head, (Bytef*)ss->head, ds->hash_size * sizeof(Pos)); 1145 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); 1146 1147 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1148 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); 1149 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; 1150 1151 ds->l_desc.dyn_tree = ds->dyn_ltree; 1152 ds->d_desc.dyn_tree = ds->dyn_dtree; 1153 ds->bl_desc.dyn_tree = ds->bl_tree; 1154 1155 return Z_OK; 1156 #endif /* MAXSEG_64K */ 1157 } 1158 1159 /* =========================================================================== 1160 * Read a new buffer from the current input stream, update the adler32 1161 * and total number of bytes read. All deflate() input goes through 1162 * this function so some applications may wish to modify it to avoid 1163 * allocating a large strm->next_in buffer and copying from it. 1164 * (See also flush_pending()). 1165 */ 1166 local unsigned read_buf( 1167 z_streamp strm, 1168 Bytef *buf, 1169 unsigned size) 1170 { 1171 unsigned len = strm->avail_in; 1172 1173 if (len > size) len = size; 1174 if (len == 0) return 0; 1175 1176 strm->avail_in -= len; 1177 1178 zmemcpy(buf, strm->next_in, len); 1179 if (strm->state->wrap == 1) { 1180 strm->adler = adler32(strm->adler, buf, len); 1181 } 1182 #ifdef GZIP 1183 else if (strm->state->wrap == 2) { 1184 strm->adler = crc32(strm->adler, buf, len); 1185 } 1186 #endif 1187 strm->next_in += len; 1188 strm->total_in += len; 1189 1190 return len; 1191 } 1192 1193 /* =========================================================================== 1194 * Initialize the "longest match" routines for a new zlib stream 1195 */ 1196 local void lm_init ( 1197 deflate_state *s) 1198 { 1199 s->window_size = (ulg)2L*s->w_size; 1200 1201 CLEAR_HASH(s); 1202 1203 /* Set the default configuration parameters: 1204 */ 1205 s->max_lazy_match = configuration_table[s->level].max_lazy; 1206 s->good_match = configuration_table[s->level].good_length; 1207 s->nice_match = configuration_table[s->level].nice_length; 1208 s->max_chain_length = configuration_table[s->level].max_chain; 1209 1210 s->strstart = 0; 1211 s->block_start = 0L; 1212 s->lookahead = 0; 1213 s->insert = 0; 1214 s->match_length = s->prev_length = MIN_MATCH-1; 1215 s->match_available = 0; 1216 s->ins_h = 0; 1217 #ifndef FASTEST 1218 #ifdef ASMV 1219 match_init(); /* initialize the asm code */ 1220 #endif 1221 #endif 1222 } 1223 1224 #ifndef FASTEST 1225 /* =========================================================================== 1226 * Set match_start to the longest match starting at the given string and 1227 * return its length. Matches shorter or equal to prev_length are discarded, 1228 * in which case the result is equal to prev_length and match_start is 1229 * garbage. 1230 * IN assertions: cur_match is the head of the hash chain for the current 1231 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1232 * OUT assertion: the match length is not greater than s->lookahead. 1233 */ 1234 #ifndef ASMV 1235 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or 1236 * match.S. The code will be functionally equivalent. 1237 */ 1238 local uInt longest_match( 1239 deflate_state *s, 1240 IPos cur_match) 1241 { 1242 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1243 register Bytef *scan = s->window + s->strstart; /* current string */ 1244 register Bytef *match; /* matched string */ 1245 register int len; /* length of current match */ 1246 int best_len = (int)s->prev_length; /* best match length so far */ 1247 int nice_match = s->nice_match; /* stop if match long enough */ 1248 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1249 s->strstart - (IPos)MAX_DIST(s) : NIL; 1250 /* Stop when cur_match becomes <= limit. To simplify the code, 1251 * we prevent matches with the string of window index 0. 1252 */ 1253 Posf *prev = s->prev; 1254 uInt wmask = s->w_mask; 1255 1256 #ifdef UNALIGNED_OK 1257 /* Compare two bytes at a time. Note: this is not always beneficial. 1258 * Try with and without -DUNALIGNED_OK to check. 1259 */ 1260 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1261 register ush scan_start = *(ushf*)scan; 1262 register ush scan_end = *(ushf*)(scan+best_len-1); 1263 #else 1264 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1265 register Byte scan_end1 = scan[best_len-1]; 1266 register Byte scan_end = scan[best_len]; 1267 #endif 1268 1269 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1270 * It is easy to get rid of this optimization if necessary. 1271 */ 1272 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1273 1274 /* Do not waste too much time if we already have a good match: */ 1275 if (s->prev_length >= s->good_match) { 1276 chain_length >>= 2; 1277 } 1278 /* Do not look for matches beyond the end of the input. This is necessary 1279 * to make deflate deterministic. 1280 */ 1281 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead; 1282 1283 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1284 1285 do { 1286 Assert(cur_match < s->strstart, "no future"); 1287 match = s->window + cur_match; 1288 1289 /* Skip to next match if the match length cannot increase 1290 * or if the match length is less than 2. Note that the checks below 1291 * for insufficient lookahead only occur occasionally for performance 1292 * reasons. Therefore uninitialized memory will be accessed, and 1293 * conditional jumps will be made that depend on those values. 1294 * However the length of the match is limited to the lookahead, so 1295 * the output of deflate is not affected by the uninitialized values. 1296 */ 1297 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1298 /* This code assumes sizeof(unsigned short) == 2. Do not use 1299 * UNALIGNED_OK if your compiler uses a different size. 1300 */ 1301 if (*(ushf*)(match+best_len-1) != scan_end || 1302 *(ushf*)match != scan_start) continue; 1303 1304 /* It is not necessary to compare scan[2] and match[2] since they are 1305 * always equal when the other bytes match, given that the hash keys 1306 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1307 * strstart+3, +5, ... up to strstart+257. We check for insufficient 1308 * lookahead only every 4th comparison; the 128th check will be made 1309 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is 1310 * necessary to put more guard bytes at the end of the window, or 1311 * to check more often for insufficient lookahead. 1312 */ 1313 Assert(scan[2] == match[2], "scan[2]?"); 1314 scan++, match++; 1315 do { 1316 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1317 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1318 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1319 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1320 scan < strend); 1321 /* The funny "do {}" generates better code on most compilers */ 1322 1323 /* Here, scan <= window+strstart+257 */ 1324 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1325 if (*scan == *match) scan++; 1326 1327 len = (MAX_MATCH - 1) - (int)(strend-scan); 1328 scan = strend - (MAX_MATCH-1); 1329 1330 #else /* UNALIGNED_OK */ 1331 1332 if (match[best_len] != scan_end || 1333 match[best_len-1] != scan_end1 || 1334 *match != *scan || 1335 *++match != scan[1]) continue; 1336 1337 /* The check at best_len-1 can be removed because it will be made 1338 * again later. (This heuristic is not always a win.) 1339 * It is not necessary to compare scan[2] and match[2] since they 1340 * are always equal when the other bytes match, given that 1341 * the hash keys are equal and that HASH_BITS >= 8. 1342 */ 1343 scan += 2, match++; 1344 Assert(*scan == *match, "match[2]?"); 1345 1346 /* We check for insufficient lookahead only every 8th comparison; 1347 * the 256th check will be made at strstart+258. 1348 */ 1349 do { 1350 } while (*++scan == *++match && *++scan == *++match && 1351 *++scan == *++match && *++scan == *++match && 1352 *++scan == *++match && *++scan == *++match && 1353 *++scan == *++match && *++scan == *++match && 1354 scan < strend); 1355 1356 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1357 1358 len = MAX_MATCH - (int)(strend - scan); 1359 scan = strend - MAX_MATCH; 1360 1361 #endif /* UNALIGNED_OK */ 1362 1363 if (len > best_len) { 1364 s->match_start = cur_match; 1365 best_len = len; 1366 if (len >= nice_match) break; 1367 #ifdef UNALIGNED_OK 1368 scan_end = *(ushf*)(scan+best_len-1); 1369 #else 1370 scan_end1 = scan[best_len-1]; 1371 scan_end = scan[best_len]; 1372 #endif 1373 } 1374 } while ((cur_match = prev[cur_match & wmask]) > limit 1375 && --chain_length != 0); 1376 1377 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1378 return s->lookahead; 1379 } 1380 #endif /* ASMV */ 1381 1382 #else /* FASTEST */ 1383 1384 /* --------------------------------------------------------------------------- 1385 * Optimized version for FASTEST only 1386 */ 1387 local uInt longest_match( 1388 deflate_state *s, 1389 IPos cur_match) 1390 { 1391 register Bytef *scan = s->window + s->strstart; /* current string */ 1392 register Bytef *match; /* matched string */ 1393 register int len; /* length of current match */ 1394 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1395 1396 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1397 * It is easy to get rid of this optimization if necessary. 1398 */ 1399 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1400 1401 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1402 1403 Assert(cur_match < s->strstart, "no future"); 1404 1405 match = s->window + cur_match; 1406 1407 /* Return failure if the match length is less than 2: 1408 */ 1409 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1410 1411 /* The check at best_len-1 can be removed because it will be made 1412 * again later. (This heuristic is not always a win.) 1413 * It is not necessary to compare scan[2] and match[2] since they 1414 * are always equal when the other bytes match, given that 1415 * the hash keys are equal and that HASH_BITS >= 8. 1416 */ 1417 scan += 2, match += 2; 1418 Assert(*scan == *match, "match[2]?"); 1419 1420 /* We check for insufficient lookahead only every 8th comparison; 1421 * the 256th check will be made at strstart+258. 1422 */ 1423 do { 1424 } while (*++scan == *++match && *++scan == *++match && 1425 *++scan == *++match && *++scan == *++match && 1426 *++scan == *++match && *++scan == *++match && 1427 *++scan == *++match && *++scan == *++match && 1428 scan < strend); 1429 1430 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1431 1432 len = MAX_MATCH - (int)(strend - scan); 1433 1434 if (len < MIN_MATCH) return MIN_MATCH - 1; 1435 1436 s->match_start = cur_match; 1437 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1438 } 1439 1440 #endif /* FASTEST */ 1441 1442 #ifdef ZLIB_DEBUG 1443 1444 #define EQUAL 0 1445 /* result of memcmp for equal strings */ 1446 1447 /* =========================================================================== 1448 * Check that the match at match_start is indeed a match. 1449 */ 1450 local void check_match( 1451 deflate_state *s, 1452 IPos start, 1453 IPos match, 1454 int length) 1455 { 1456 /* check that the match is indeed a match */ 1457 if (zmemcmp(s->window + match, 1458 s->window + start, length) != EQUAL) { 1459 fprintf(stderr, " start %u, match %u, length %d\n", 1460 start, match, length); 1461 do { 1462 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); 1463 } while (--length != 0); 1464 z_error("invalid match"); 1465 } 1466 if (z_verbose > 1) { 1467 fprintf(stderr,"\\[%d,%d]", start-match, length); 1468 do { putc(s->window[start++], stderr); } while (--length != 0); 1469 } 1470 } 1471 #else 1472 # define check_match(s, start, match, length) 1473 #endif /* ZLIB_DEBUG */ 1474 1475 /* =========================================================================== 1476 * Fill the window when the lookahead becomes insufficient. 1477 * Updates strstart and lookahead. 1478 * 1479 * IN assertion: lookahead < MIN_LOOKAHEAD 1480 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 1481 * At least one byte has been read, or avail_in == 0; reads are 1482 * performed for at least two bytes (required for the zip translate_eol 1483 * option -- not supported here). 1484 */ 1485 local void fill_window( 1486 deflate_state *s) 1487 { 1488 unsigned n; 1489 unsigned more; /* Amount of free space at the end of the window. */ 1490 uInt wsize = s->w_size; 1491 1492 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); 1493 1494 do { 1495 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 1496 1497 /* Deal with !@#$% 64K limit: */ 1498 if (sizeof(int) <= 2) { 1499 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 1500 more = wsize; 1501 1502 } else if (more == (unsigned)(-1)) { 1503 /* Very unlikely, but possible on 16 bit machine if 1504 * strstart == 0 && lookahead == 1 (input done a byte at time) 1505 */ 1506 more--; 1507 } 1508 } 1509 1510 /* If the window is almost full and there is insufficient lookahead, 1511 * move the upper half to the lower one to make room in the upper half. 1512 */ 1513 if (s->strstart >= wsize+MAX_DIST(s)) { 1514 1515 zmemcpy(s->window, s->window+wsize, (unsigned)wsize - more); 1516 s->match_start -= wsize; 1517 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 1518 s->block_start -= (long) wsize; 1519 slide_hash(s); 1520 more += wsize; 1521 } 1522 if (s->strm->avail_in == 0) break; 1523 1524 /* If there was no sliding: 1525 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 1526 * more == window_size - lookahead - strstart 1527 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 1528 * => more >= window_size - 2*WSIZE + 2 1529 * In the BIG_MEM or MMAP case (not yet supported), 1530 * window_size == input_size + MIN_LOOKAHEAD && 1531 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 1532 * Otherwise, window_size == 2*WSIZE so more >= 2. 1533 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 1534 */ 1535 Assert(more >= 2, "more < 2"); 1536 1537 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 1538 s->lookahead += n; 1539 1540 /* Initialize the hash value now that we have some input: */ 1541 if (s->lookahead + s->insert >= MIN_MATCH) { 1542 uInt str = s->strstart - s->insert; 1543 s->ins_h = s->window[str]; 1544 UPDATE_HASH(s, s->ins_h, s->window[str + 1]); 1545 #if MIN_MATCH != 3 1546 Call UPDATE_HASH() MIN_MATCH-3 more times 1547 #endif 1548 while (s->insert) { 1549 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 1550 #ifndef FASTEST 1551 s->prev[str & s->w_mask] = s->head[s->ins_h]; 1552 #endif 1553 s->head[s->ins_h] = (Pos)str; 1554 str++; 1555 s->insert--; 1556 if (s->lookahead + s->insert < MIN_MATCH) 1557 break; 1558 } 1559 } 1560 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 1561 * but this is not important since only literal bytes will be emitted. 1562 */ 1563 1564 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 1565 1566 /* If the WIN_INIT bytes after the end of the current data have never been 1567 * written, then zero those bytes in order to avoid memory check reports of 1568 * the use of uninitialized (or uninitialised as Julian writes) bytes by 1569 * the longest match routines. Update the high water mark for the next 1570 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 1571 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 1572 */ 1573 if (s->high_water < s->window_size) { 1574 ulg curr = s->strstart + (ulg)(s->lookahead); 1575 ulg init; 1576 1577 if (s->high_water < curr) { 1578 /* Previous high water mark below current data -- zero WIN_INIT 1579 * bytes or up to end of window, whichever is less. 1580 */ 1581 init = s->window_size - curr; 1582 if (init > WIN_INIT) 1583 init = WIN_INIT; 1584 zmemzero(s->window + curr, (unsigned)init); 1585 s->high_water = curr + init; 1586 } 1587 else if (s->high_water < (ulg)curr + WIN_INIT) { 1588 /* High water mark at or above current data, but below current data 1589 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 1590 * to end of window, whichever is less. 1591 */ 1592 init = (ulg)curr + WIN_INIT - s->high_water; 1593 if (init > s->window_size - s->high_water) 1594 init = s->window_size - s->high_water; 1595 zmemzero(s->window + s->high_water, (unsigned)init); 1596 s->high_water += init; 1597 } 1598 } 1599 1600 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1601 "not enough room for search"); 1602 } 1603 1604 /* =========================================================================== 1605 * Flush the current block, with given end-of-file flag. 1606 * IN assertion: strstart is set to the end of the current match. 1607 */ 1608 #define FLUSH_BLOCK_ONLY(s, last) { \ 1609 _tr_flush_block(s, (s->block_start >= 0L ? \ 1610 (charf *)&s->window[(unsigned)s->block_start] : \ 1611 (charf *)Z_NULL), \ 1612 (ulg)((long)s->strstart - s->block_start), \ 1613 (last)); \ 1614 s->block_start = s->strstart; \ 1615 flush_pending(s->strm); \ 1616 Tracev((stderr,"[FLUSH]")); \ 1617 } 1618 1619 /* Same but force premature exit if necessary. */ 1620 #define FLUSH_BLOCK(s, last) { \ 1621 FLUSH_BLOCK_ONLY(s, last); \ 1622 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1623 } 1624 1625 /* Maximum stored block length in deflate format (not including header). */ 1626 #define MAX_STORED 65535 1627 1628 /* Minimum of a and b. */ 1629 #define MIN(a, b) ((a) > (b) ? (b) : (a)) 1630 1631 /* =========================================================================== 1632 * Copy without compression as much as possible from the input stream, return 1633 * the current block state. 1634 * 1635 * In case deflateParams() is used to later switch to a non-zero compression 1636 * level, s->matches (otherwise unused when storing) keeps track of the number 1637 * of hash table slides to perform. If s->matches is 1, then one hash table 1638 * slide will be done when switching. If s->matches is 2, the maximum value 1639 * allowed here, then the hash table will be cleared, since two or more slides 1640 * is the same as a clear. 1641 * 1642 * deflate_stored() is written to minimize the number of times an input byte is 1643 * copied. It is most efficient with large input and output buffers, which 1644 * maximizes the opportunites to have a single copy from next_in to next_out. 1645 */ 1646 local block_state deflate_stored( 1647 deflate_state *s, 1648 int flush) 1649 { 1650 /* Smallest worthy block size when not flushing or finishing. By default 1651 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For 1652 * large input and output buffers, the stored block size will be larger. 1653 */ 1654 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size); 1655 1656 /* Copy as many min_block or larger stored blocks directly to next_out as 1657 * possible. If flushing, copy the remaining available input to next_out as 1658 * stored blocks, if there is enough space. 1659 */ 1660 unsigned len, left, have, last = 0; 1661 unsigned used = s->strm->avail_in; 1662 do { 1663 /* Set len to the maximum size block that we can copy directly with the 1664 * available input data and output space. Set left to how much of that 1665 * would be copied from what's left in the window. 1666 */ 1667 len = MAX_STORED; /* maximum deflate stored block length */ 1668 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1669 if (s->strm->avail_out < have) /* need room for header */ 1670 break; 1671 /* maximum stored block length that will fit in avail_out: */ 1672 have = s->strm->avail_out - have; 1673 left = s->strstart - s->block_start; /* bytes left in window */ 1674 if (len > (ulg)left + s->strm->avail_in) 1675 len = left + s->strm->avail_in; /* limit len to the input */ 1676 if (len > have) 1677 len = have; /* limit len to the output */ 1678 1679 /* If the stored block would be less than min_block in length, or if 1680 * unable to copy all of the available input when flushing, then try 1681 * copying to the window and the pending buffer instead. Also don't 1682 * write an empty block when flushing -- deflate() does that. 1683 */ 1684 if (len < min_block && ((len == 0 && flush != Z_FINISH) || 1685 flush == Z_NO_FLUSH || 1686 len != left + s->strm->avail_in)) 1687 break; 1688 1689 /* Make a dummy stored block in pending to get the header bytes, 1690 * including any pending bits. This also updates the debugging counts. 1691 */ 1692 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0; 1693 _tr_stored_block(s, (char *)0, 0L, last); 1694 1695 /* Replace the lengths in the dummy stored block with len. */ 1696 s->pending_buf[s->pending - 4] = len; 1697 s->pending_buf[s->pending - 3] = len >> 8; 1698 s->pending_buf[s->pending - 2] = ~len; 1699 s->pending_buf[s->pending - 1] = ~len >> 8; 1700 1701 /* Write the stored block header bytes. */ 1702 flush_pending(s->strm); 1703 1704 #ifdef ZLIB_DEBUG 1705 /* Update debugging counts for the data about to be copied. */ 1706 s->compressed_len += len << 3; 1707 s->bits_sent += len << 3; 1708 #endif 1709 1710 /* Copy uncompressed bytes from the window to next_out. */ 1711 if (left) { 1712 if (left > len) 1713 left = len; 1714 zmemcpy(s->strm->next_out, s->window + s->block_start, left); 1715 s->strm->next_out += left; 1716 s->strm->avail_out -= left; 1717 s->strm->total_out += left; 1718 s->block_start += left; 1719 len -= left; 1720 } 1721 1722 /* Copy uncompressed bytes directly from next_in to next_out, updating 1723 * the check value. 1724 */ 1725 if (len) { 1726 read_buf(s->strm, s->strm->next_out, len); 1727 s->strm->next_out += len; 1728 s->strm->avail_out -= len; 1729 s->strm->total_out += len; 1730 } 1731 } while (last == 0); 1732 1733 /* Update the sliding window with the last s->w_size bytes of the copied 1734 * data, or append all of the copied data to the existing window if less 1735 * than s->w_size bytes were copied. Also update the number of bytes to 1736 * insert in the hash tables, in the event that deflateParams() switches to 1737 * a non-zero compression level. 1738 */ 1739 used -= s->strm->avail_in; /* number of input bytes directly copied */ 1740 if (used) { 1741 /* If any input was used, then no unused input remains in the window, 1742 * therefore s->block_start == s->strstart. 1743 */ 1744 if (used >= s->w_size) { /* supplant the previous history */ 1745 s->matches = 2; /* clear hash */ 1746 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size); 1747 s->strstart = s->w_size; 1748 } 1749 else { 1750 if (s->window_size - s->strstart <= used) { 1751 /* Slide the window down. */ 1752 s->strstart -= s->w_size; 1753 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1754 if (s->matches < 2) 1755 s->matches++; /* add a pending slide_hash() */ 1756 } 1757 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used); 1758 s->strstart += used; 1759 } 1760 s->block_start = s->strstart; 1761 s->insert += MIN(used, s->w_size - s->insert); 1762 } 1763 if (s->high_water < s->strstart) 1764 s->high_water = s->strstart; 1765 1766 /* If the last block was written to next_out, then done. */ 1767 if (last) 1768 return finish_done; 1769 1770 /* If flushing and all input has been consumed, then done. */ 1771 if (flush != Z_NO_FLUSH && flush != Z_FINISH && 1772 s->strm->avail_in == 0 && (long)s->strstart == s->block_start) 1773 return block_done; 1774 1775 /* Fill the window with any remaining input. */ 1776 have = s->window_size - s->strstart - 1; 1777 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) { 1778 /* Slide the window down. */ 1779 s->block_start -= s->w_size; 1780 s->strstart -= s->w_size; 1781 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1782 if (s->matches < 2) 1783 s->matches++; /* add a pending slide_hash() */ 1784 have += s->w_size; /* more space now */ 1785 } 1786 if (have > s->strm->avail_in) 1787 have = s->strm->avail_in; 1788 if (have) { 1789 read_buf(s->strm, s->window + s->strstart, have); 1790 s->strstart += have; 1791 } 1792 if (s->high_water < s->strstart) 1793 s->high_water = s->strstart; 1794 1795 /* There was not enough avail_out to write a complete worthy or flushed 1796 * stored block to next_out. Write a stored block to pending instead, if we 1797 * have enough input for a worthy block, or if flushing and there is enough 1798 * room for the remaining input as a stored block in the pending buffer. 1799 */ 1800 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1801 /* maximum stored block length that will fit in pending: */ 1802 have = MIN(s->pending_buf_size - have, MAX_STORED); 1803 min_block = MIN(have, s->w_size); 1804 left = s->strstart - s->block_start; 1805 if (left >= min_block || 1806 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH && 1807 s->strm->avail_in == 0 && left <= have)) { 1808 len = MIN(left, have); 1809 last = flush == Z_FINISH && s->strm->avail_in == 0 && 1810 len == left ? 1 : 0; 1811 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last); 1812 s->block_start += len; 1813 flush_pending(s->strm); 1814 } 1815 1816 /* We've done all we can with the available input and output. */ 1817 return last ? finish_started : need_more; 1818 } 1819 1820 /* =========================================================================== 1821 * Compress as much as possible from the input stream, return the current 1822 * block state. 1823 * This function does not perform lazy evaluation of matches and inserts 1824 * new strings in the dictionary only for unmatched strings or for short 1825 * matches. It is used only for the fast compression options. 1826 */ 1827 local block_state deflate_fast( 1828 deflate_state *s, 1829 int flush) 1830 { 1831 IPos hash_head; /* head of the hash chain */ 1832 int bflush; /* set if current block must be flushed */ 1833 1834 for (;;) { 1835 /* Make sure that we always have enough lookahead, except 1836 * at the end of the input file. We need MAX_MATCH bytes 1837 * for the next match, plus MIN_MATCH bytes to insert the 1838 * string following the next match. 1839 */ 1840 if (s->lookahead < MIN_LOOKAHEAD) { 1841 fill_window(s); 1842 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1843 return need_more; 1844 } 1845 if (s->lookahead == 0) break; /* flush the current block */ 1846 } 1847 1848 /* Insert the string window[strstart .. strstart+2] in the 1849 * dictionary, and set hash_head to the head of the hash chain: 1850 */ 1851 hash_head = NIL; 1852 if (s->lookahead >= MIN_MATCH) { 1853 INSERT_STRING(s, s->strstart, hash_head); 1854 } 1855 1856 /* Find the longest match, discarding those <= prev_length. 1857 * At this point we have always match_length < MIN_MATCH 1858 */ 1859 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1860 /* To simplify the code, we prevent matches with the string 1861 * of window index 0 (in particular we have to avoid a match 1862 * of the string with itself at the start of the input file). 1863 */ 1864 s->match_length = longest_match (s, hash_head); 1865 /* longest_match() sets match_start */ 1866 } 1867 if (s->match_length >= MIN_MATCH) { 1868 check_match(s, s->strstart, s->match_start, s->match_length); 1869 1870 _tr_tally_dist(s, s->strstart - s->match_start, 1871 s->match_length - MIN_MATCH, bflush); 1872 1873 s->lookahead -= s->match_length; 1874 1875 /* Insert new strings in the hash table only if the match length 1876 * is not too large. This saves time but degrades compression. 1877 */ 1878 #ifndef FASTEST 1879 if (s->match_length <= s->max_insert_length && 1880 s->lookahead >= MIN_MATCH) { 1881 s->match_length--; /* string at strstart already in table */ 1882 do { 1883 s->strstart++; 1884 INSERT_STRING(s, s->strstart, hash_head); 1885 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1886 * always MIN_MATCH bytes ahead. 1887 */ 1888 } while (--s->match_length != 0); 1889 s->strstart++; 1890 } else 1891 #endif 1892 { 1893 s->strstart += s->match_length; 1894 s->match_length = 0; 1895 s->ins_h = s->window[s->strstart]; 1896 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); 1897 #if MIN_MATCH != 3 1898 Call UPDATE_HASH() MIN_MATCH-3 more times 1899 #endif 1900 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1901 * matter since it will be recomputed at next deflate call. 1902 */ 1903 } 1904 } else { 1905 /* No match, output a literal byte */ 1906 Tracevv((stderr,"%c", s->window[s->strstart])); 1907 _tr_tally_lit (s, s->window[s->strstart], bflush); 1908 s->lookahead--; 1909 s->strstart++; 1910 } 1911 if (bflush) FLUSH_BLOCK(s, 0); 1912 } 1913 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1914 if (flush == Z_FINISH) { 1915 FLUSH_BLOCK(s, 1); 1916 return finish_done; 1917 } 1918 if (s->last_lit) 1919 FLUSH_BLOCK(s, 0); 1920 return block_done; 1921 } 1922 1923 #ifndef FASTEST 1924 /* =========================================================================== 1925 * Same as above, but achieves better compression. We use a lazy 1926 * evaluation for matches: a match is finally adopted only if there is 1927 * no better match at the next window position. 1928 */ 1929 local block_state deflate_slow( 1930 deflate_state *s, 1931 int flush) 1932 { 1933 IPos hash_head; /* head of hash chain */ 1934 int bflush; /* set if current block must be flushed */ 1935 1936 /* Process the input block. */ 1937 for (;;) { 1938 /* Make sure that we always have enough lookahead, except 1939 * at the end of the input file. We need MAX_MATCH bytes 1940 * for the next match, plus MIN_MATCH bytes to insert the 1941 * string following the next match. 1942 */ 1943 if (s->lookahead < MIN_LOOKAHEAD) { 1944 fill_window(s); 1945 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1946 return need_more; 1947 } 1948 if (s->lookahead == 0) break; /* flush the current block */ 1949 } 1950 1951 /* Insert the string window[strstart .. strstart+2] in the 1952 * dictionary, and set hash_head to the head of the hash chain: 1953 */ 1954 hash_head = NIL; 1955 if (s->lookahead >= MIN_MATCH) { 1956 INSERT_STRING(s, s->strstart, hash_head); 1957 } 1958 1959 /* Find the longest match, discarding those <= prev_length. 1960 */ 1961 s->prev_length = s->match_length, s->prev_match = s->match_start; 1962 s->match_length = MIN_MATCH-1; 1963 1964 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1965 s->strstart - hash_head <= MAX_DIST(s)) { 1966 /* To simplify the code, we prevent matches with the string 1967 * of window index 0 (in particular we have to avoid a match 1968 * of the string with itself at the start of the input file). 1969 */ 1970 s->match_length = longest_match (s, hash_head); 1971 /* longest_match() sets match_start */ 1972 1973 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1974 #if TOO_FAR <= 32767 1975 || (s->match_length == MIN_MATCH && 1976 s->strstart - s->match_start > TOO_FAR) 1977 #endif 1978 )) { 1979 1980 /* If prev_match is also MIN_MATCH, match_start is garbage 1981 * but we will ignore the current match anyway. 1982 */ 1983 s->match_length = MIN_MATCH-1; 1984 } 1985 } 1986 /* If there was a match at the previous step and the current 1987 * match is not better, output the previous match: 1988 */ 1989 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1990 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1991 /* Do not insert strings in hash table beyond this. */ 1992 1993 check_match(s, s->strstart-1, s->prev_match, s->prev_length); 1994 1995 _tr_tally_dist(s, s->strstart -1 - s->prev_match, 1996 s->prev_length - MIN_MATCH, bflush); 1997 1998 /* Insert in hash table all strings up to the end of the match. 1999 * strstart-1 and strstart are already inserted. If there is not 2000 * enough lookahead, the last two strings are not inserted in 2001 * the hash table. 2002 */ 2003 s->lookahead -= s->prev_length-1; 2004 s->prev_length -= 2; 2005 do { 2006 if (++s->strstart <= max_insert) { 2007 INSERT_STRING(s, s->strstart, hash_head); 2008 } 2009 } while (--s->prev_length != 0); 2010 s->match_available = 0; 2011 s->match_length = MIN_MATCH-1; 2012 s->strstart++; 2013 2014 if (bflush) FLUSH_BLOCK(s, 0); 2015 2016 } else if (s->match_available) { 2017 /* If there was no match at the previous position, output a 2018 * single literal. If there was a match but the current match 2019 * is longer, truncate the previous match to a single literal. 2020 */ 2021 Tracevv((stderr,"%c", s->window[s->strstart-1])); 2022 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 2023 if (bflush) { 2024 FLUSH_BLOCK_ONLY(s, 0); 2025 } 2026 s->strstart++; 2027 s->lookahead--; 2028 if (s->strm->avail_out == 0) return need_more; 2029 } else { 2030 /* There is no previous match to compare with, wait for 2031 * the next step to decide. 2032 */ 2033 s->match_available = 1; 2034 s->strstart++; 2035 s->lookahead--; 2036 } 2037 } 2038 Assert (flush != Z_NO_FLUSH, "no flush?"); 2039 if (s->match_available) { 2040 Tracevv((stderr,"%c", s->window[s->strstart-1])); 2041 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 2042 s->match_available = 0; 2043 } 2044 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 2045 if (flush == Z_FINISH) { 2046 FLUSH_BLOCK(s, 1); 2047 return finish_done; 2048 } 2049 if (s->last_lit) 2050 FLUSH_BLOCK(s, 0); 2051 return block_done; 2052 } 2053 #endif /* FASTEST */ 2054 2055 /* =========================================================================== 2056 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 2057 * one. Do not maintain a hash table. (It will be regenerated if this run of 2058 * deflate switches away from Z_RLE.) 2059 */ 2060 local block_state deflate_rle( 2061 deflate_state *s, 2062 int flush) 2063 { 2064 int bflush; /* set if current block must be flushed */ 2065 uInt prev; /* byte at distance one to match */ 2066 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 2067 2068 for (;;) { 2069 /* Make sure that we always have enough lookahead, except 2070 * at the end of the input file. We need MAX_MATCH bytes 2071 * for the longest run, plus one for the unrolled loop. 2072 */ 2073 if (s->lookahead <= MAX_MATCH) { 2074 fill_window(s); 2075 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 2076 return need_more; 2077 } 2078 if (s->lookahead == 0) break; /* flush the current block */ 2079 } 2080 2081 /* See how many times the previous byte repeats */ 2082 s->match_length = 0; 2083 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 2084 scan = s->window + s->strstart - 1; 2085 prev = *scan; 2086 if (prev == *++scan && prev == *++scan && prev == *++scan) { 2087 strend = s->window + s->strstart + MAX_MATCH; 2088 do { 2089 } while (prev == *++scan && prev == *++scan && 2090 prev == *++scan && prev == *++scan && 2091 prev == *++scan && prev == *++scan && 2092 prev == *++scan && prev == *++scan && 2093 scan < strend); 2094 s->match_length = MAX_MATCH - (uInt)(strend - scan); 2095 if (s->match_length > s->lookahead) 2096 s->match_length = s->lookahead; 2097 } 2098 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan"); 2099 } 2100 2101 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 2102 if (s->match_length >= MIN_MATCH) { 2103 check_match(s, s->strstart, s->strstart - 1, s->match_length); 2104 2105 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 2106 2107 s->lookahead -= s->match_length; 2108 s->strstart += s->match_length; 2109 s->match_length = 0; 2110 } else { 2111 /* No match, output a literal byte */ 2112 Tracevv((stderr,"%c", s->window[s->strstart])); 2113 _tr_tally_lit (s, s->window[s->strstart], bflush); 2114 s->lookahead--; 2115 s->strstart++; 2116 } 2117 if (bflush) FLUSH_BLOCK(s, 0); 2118 } 2119 s->insert = 0; 2120 if (flush == Z_FINISH) { 2121 FLUSH_BLOCK(s, 1); 2122 return finish_done; 2123 } 2124 if (s->last_lit) 2125 FLUSH_BLOCK(s, 0); 2126 return block_done; 2127 } 2128 2129 /* =========================================================================== 2130 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 2131 * (It will be regenerated if this run of deflate switches away from Huffman.) 2132 */ 2133 local block_state deflate_huff( 2134 deflate_state *s, 2135 int flush) 2136 { 2137 int bflush; /* set if current block must be flushed */ 2138 2139 for (;;) { 2140 /* Make sure that we have a literal to write. */ 2141 if (s->lookahead == 0) { 2142 fill_window(s); 2143 if (s->lookahead == 0) { 2144 if (flush == Z_NO_FLUSH) 2145 return need_more; 2146 break; /* flush the current block */ 2147 } 2148 } 2149 2150 /* Output a literal byte */ 2151 s->match_length = 0; 2152 Tracevv((stderr,"%c", s->window[s->strstart])); 2153 _tr_tally_lit (s, s->window[s->strstart], bflush); 2154 s->lookahead--; 2155 s->strstart++; 2156 if (bflush) FLUSH_BLOCK(s, 0); 2157 } 2158 s->insert = 0; 2159 if (flush == Z_FINISH) { 2160 FLUSH_BLOCK(s, 1); 2161 return finish_done; 2162 } 2163 if (s->last_lit) 2164 FLUSH_BLOCK(s, 0); 2165 return block_done; 2166 } 2167