1 /* $OpenBSD: deflate.c,v 1.6 2021/07/28 07:36:06 tb Exp $ */ 2 /* deflate.c -- compress data using the deflation algorithm 3 * Copyright (C) 1995-2017 Jean-loup Gailly and Mark Adler 4 * For conditions of distribution and use, see copyright notice in zlib.h 5 */ 6 7 /* 8 * ALGORITHM 9 * 10 * The "deflation" process depends on being able to identify portions 11 * of the input text which are identical to earlier input (within a 12 * sliding window trailing behind the input currently being processed). 13 * 14 * The most straightforward technique turns out to be the fastest for 15 * most input files: try all possible matches and select the longest. 16 * The key feature of this algorithm is that insertions into the string 17 * dictionary are very simple and thus fast, and deletions are avoided 18 * completely. Insertions are performed at each input character, whereas 19 * string matches are performed only when the previous match ends. So it 20 * is preferable to spend more time in matches to allow very fast string 21 * insertions and avoid deletions. The matching algorithm for small 22 * strings is inspired from that of Rabin & Karp. A brute force approach 23 * is used to find longer strings when a small match has been found. 24 * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze 25 * (by Leonid Broukhis). 26 * A previous version of this file used a more sophisticated algorithm 27 * (by Fiala and Greene) which is guaranteed to run in linear amortized 28 * time, but has a larger average cost, uses more memory and is patented. 29 * However the F&G algorithm may be faster for some highly redundant 30 * files if the parameter max_chain_length (described below) is too large. 31 * 32 * ACKNOWLEDGEMENTS 33 * 34 * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and 35 * I found it in 'freeze' written by Leonid Broukhis. 36 * Thanks to many people for bug reports and testing. 37 * 38 * REFERENCES 39 * 40 * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification". 41 * Available in http://tools.ietf.org/html/rfc1951 42 * 43 * A description of the Rabin and Karp algorithm is given in the book 44 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252. 45 * 46 * Fiala,E.R., and Greene,D.H. 47 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595 48 * 49 */ 50 51 #include "deflate.h" 52 53 /* 54 If you use the zlib library in a product, an acknowledgment is welcome 55 in the documentation of your product. If for some reason you cannot 56 include such an acknowledgment, I would appreciate that you keep this 57 copyright string in the executable of your product. 58 */ 59 60 /* =========================================================================== 61 * Function prototypes. 62 */ 63 typedef enum { 64 need_more, /* block not completed, need more input or more output */ 65 block_done, /* block flush performed */ 66 finish_started, /* finish started, need only more output at next deflate */ 67 finish_done /* finish done, accept no more input or output */ 68 } block_state; 69 70 typedef block_state (*compress_func) OF((deflate_state *s, int flush)); 71 /* Compression function. Returns the block state after the call. */ 72 73 local int deflateStateCheck OF((z_streamp strm)); 74 local void slide_hash OF((deflate_state *s)); 75 local void fill_window OF((deflate_state *s)); 76 local block_state deflate_stored OF((deflate_state *s, int flush)); 77 local block_state deflate_fast OF((deflate_state *s, int flush)); 78 #ifndef FASTEST 79 local block_state deflate_slow OF((deflate_state *s, int flush)); 80 #endif 81 local block_state deflate_rle OF((deflate_state *s, int flush)); 82 local block_state deflate_huff OF((deflate_state *s, int flush)); 83 local void lm_init OF((deflate_state *s)); 84 local void putShortMSB OF((deflate_state *s, uInt b)); 85 local void flush_pending OF((z_streamp strm)); 86 local unsigned read_buf OF((z_streamp strm, Bytef *buf, unsigned size)); 87 #ifdef ASMV 88 # pragma message("Assembler code may have bugs -- use at your own risk") 89 void match_init OF((void)); /* asm code initialization */ 90 uInt longest_match OF((deflate_state *s, IPos cur_match)); 91 #else 92 local uInt longest_match OF((deflate_state *s, IPos cur_match)); 93 #endif 94 95 #ifdef ZLIB_DEBUG 96 local void check_match OF((deflate_state *s, IPos start, IPos match, 97 int length)); 98 #endif 99 100 /* =========================================================================== 101 * Local data 102 */ 103 104 #define NIL 0 105 /* Tail of hash chains */ 106 107 #ifndef TOO_FAR 108 # define TOO_FAR 4096 109 #endif 110 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ 111 112 /* Values for max_lazy_match, good_match and max_chain_length, depending on 113 * the desired pack level (0..9). The values given below have been tuned to 114 * exclude worst case performance for pathological files. Better values may be 115 * found for specific files. 116 */ 117 typedef struct config_s { 118 ush good_length; /* reduce lazy search above this match length */ 119 ush max_lazy; /* do not perform lazy search above this match length */ 120 ush nice_length; /* quit search above this match length */ 121 ush max_chain; 122 compress_func func; 123 } config; 124 125 #ifdef FASTEST 126 local const config configuration_table[2] = { 127 /* good lazy nice chain */ 128 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 129 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ 130 #else 131 local const config configuration_table[10] = { 132 /* good lazy nice chain */ 133 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 134 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ 135 /* 2 */ {4, 5, 16, 8, deflate_fast}, 136 /* 3 */ {4, 6, 32, 32, deflate_fast}, 137 138 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ 139 /* 5 */ {8, 16, 32, 32, deflate_slow}, 140 /* 6 */ {8, 16, 128, 128, deflate_slow}, 141 /* 7 */ {8, 32, 128, 256, deflate_slow}, 142 /* 8 */ {32, 128, 258, 1024, deflate_slow}, 143 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ 144 #endif 145 146 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 147 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different 148 * meaning. 149 */ 150 151 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */ 152 #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0)) 153 154 /* =========================================================================== 155 * Update a hash value with the given input byte 156 * IN assertion: all calls to UPDATE_HASH are made with consecutive input 157 * characters, so that a running hash key can be computed from the previous 158 * key instead of complete recalculation each time. 159 */ 160 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask) 161 162 163 /* =========================================================================== 164 * Insert string str in the dictionary and set match_head to the previous head 165 * of the hash chain (the most recent string with same hash key). Return 166 * the previous length of the hash chain. 167 * If this file is compiled with -DFASTEST, the compression level is forced 168 * to 1, and no hash chains are maintained. 169 * IN assertion: all calls to INSERT_STRING are made with consecutive input 170 * characters and the first MIN_MATCH bytes of str are valid (except for 171 * the last MIN_MATCH-1 bytes of the input file). 172 */ 173 #ifdef FASTEST 174 #define INSERT_STRING(s, str, match_head) \ 175 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 176 match_head = s->head[s->ins_h], \ 177 s->head[s->ins_h] = (Pos)(str)) 178 #else 179 #define INSERT_STRING(s, str, match_head) \ 180 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 181 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ 182 s->head[s->ins_h] = (Pos)(str)) 183 #endif 184 185 /* =========================================================================== 186 * Initialize the hash table (avoiding 64K overflow for 16 bit systems). 187 * prev[] will be initialized on the fly. 188 */ 189 #define CLEAR_HASH(s) \ 190 s->head[s->hash_size-1] = NIL; \ 191 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head)); 192 193 /* =========================================================================== 194 * Slide the hash table when sliding the window down (could be avoided with 32 195 * bit values at the expense of memory usage). We slide even when level == 0 to 196 * keep the hash table consistent if we switch back to level > 0 later. 197 */ 198 local void slide_hash(s) 199 deflate_state *s; 200 { 201 unsigned n, m; 202 Posf *p; 203 uInt wsize = s->w_size; 204 205 n = s->hash_size; 206 p = &s->head[n]; 207 do { 208 m = *--p; 209 *p = (Pos)(m >= wsize ? m - wsize : NIL); 210 } while (--n); 211 n = wsize; 212 #ifndef FASTEST 213 p = &s->prev[n]; 214 do { 215 m = *--p; 216 *p = (Pos)(m >= wsize ? m - wsize : NIL); 217 /* If n is not on any hash chain, prev[n] is garbage but 218 * its value will never be used. 219 */ 220 } while (--n); 221 #endif 222 } 223 224 /* ========================================================================= */ 225 int ZEXPORT deflateInit_(strm, level, version, stream_size) 226 z_streamp strm; 227 int level; 228 const char *version; 229 int stream_size; 230 { 231 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, 232 Z_DEFAULT_STRATEGY, version, stream_size); 233 /* To do: ignore strm->next_in if we use it as window */ 234 } 235 236 /* ========================================================================= */ 237 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy, 238 version, stream_size) 239 z_streamp strm; 240 int level; 241 int method; 242 int windowBits; 243 int memLevel; 244 int strategy; 245 const char *version; 246 int stream_size; 247 { 248 deflate_state *s; 249 int wrap = 1; 250 static const char my_version[] = ZLIB_VERSION; 251 252 ushf *overlay; 253 /* We overlay pending_buf and d_buf+l_buf. This works since the average 254 * output size for (length,distance) codes is <= 24 bits. 255 */ 256 257 if (version == Z_NULL || version[0] != my_version[0] || 258 stream_size != sizeof(z_stream)) { 259 return Z_VERSION_ERROR; 260 } 261 if (strm == Z_NULL) return Z_STREAM_ERROR; 262 263 strm->msg = Z_NULL; 264 if (strm->zalloc == (alloc_func)0) { 265 #ifdef Z_SOLO 266 return Z_STREAM_ERROR; 267 #else 268 strm->zalloc = zcalloc; 269 strm->opaque = (voidpf)0; 270 #endif 271 } 272 if (strm->zfree == (free_func)0) 273 #ifdef Z_SOLO 274 return Z_STREAM_ERROR; 275 #else 276 strm->zfree = zcfree; 277 #endif 278 279 #ifdef FASTEST 280 if (level != 0) level = 1; 281 #else 282 if (level == Z_DEFAULT_COMPRESSION) level = 6; 283 #endif 284 285 if (windowBits < 0) { /* suppress zlib wrapper */ 286 wrap = 0; 287 windowBits = -windowBits; 288 } 289 #ifdef GZIP 290 else if (windowBits > 15) { 291 wrap = 2; /* write gzip wrapper instead */ 292 windowBits -= 16; 293 } 294 #endif 295 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 296 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 297 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) { 298 return Z_STREAM_ERROR; 299 } 300 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 301 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 302 if (s == Z_NULL) return Z_MEM_ERROR; 303 strm->state = (struct internal_state FAR *)s; 304 s->strm = strm; 305 s->status = INIT_STATE; /* to pass state test in deflateReset() */ 306 307 s->wrap = wrap; 308 s->gzhead = Z_NULL; 309 s->w_bits = (uInt)windowBits; 310 s->w_size = 1 << s->w_bits; 311 s->w_mask = s->w_size - 1; 312 313 s->hash_bits = (uInt)memLevel + 7; 314 s->hash_size = 1 << s->hash_bits; 315 s->hash_mask = s->hash_size - 1; 316 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); 317 318 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 319 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 320 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 321 322 s->high_water = 0; /* nothing written to s->window yet */ 323 324 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 325 326 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); 327 s->pending_buf = (uchf *) overlay; 328 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); 329 330 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 331 s->pending_buf == Z_NULL) { 332 s->status = FINISH_STATE; 333 strm->msg = ERR_MSG(Z_MEM_ERROR); 334 deflateEnd (strm); 335 return Z_MEM_ERROR; 336 } 337 s->d_buf = overlay + s->lit_bufsize/sizeof(ush); 338 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; 339 340 s->level = level; 341 s->strategy = strategy; 342 s->method = (Byte)method; 343 344 return deflateReset(strm); 345 } 346 347 /* ========================================================================= 348 * Check for a valid deflate stream state. Return 0 if ok, 1 if not. 349 */ 350 local int deflateStateCheck (strm) 351 z_streamp strm; 352 { 353 deflate_state *s; 354 if (strm == Z_NULL || 355 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) 356 return 1; 357 s = strm->state; 358 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE && 359 #ifdef GZIP 360 s->status != GZIP_STATE && 361 #endif 362 s->status != EXTRA_STATE && 363 s->status != NAME_STATE && 364 s->status != COMMENT_STATE && 365 s->status != HCRC_STATE && 366 s->status != BUSY_STATE && 367 s->status != FINISH_STATE)) 368 return 1; 369 return 0; 370 } 371 372 /* ========================================================================= */ 373 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength) 374 z_streamp strm; 375 const Bytef *dictionary; 376 uInt dictLength; 377 { 378 deflate_state *s; 379 uInt str, n; 380 int wrap; 381 unsigned avail; 382 z_const unsigned char *next; 383 384 if (deflateStateCheck(strm) || dictionary == Z_NULL) 385 return Z_STREAM_ERROR; 386 s = strm->state; 387 wrap = s->wrap; 388 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) 389 return Z_STREAM_ERROR; 390 391 /* when using zlib wrappers, compute Adler-32 for provided dictionary */ 392 if (wrap == 1) 393 strm->adler = adler32(strm->adler, dictionary, dictLength); 394 s->wrap = 0; /* avoid computing Adler-32 in read_buf */ 395 396 /* if dictionary would fill window, just replace the history */ 397 if (dictLength >= s->w_size) { 398 if (wrap == 0) { /* already empty otherwise */ 399 CLEAR_HASH(s); 400 s->strstart = 0; 401 s->block_start = 0L; 402 s->insert = 0; 403 } 404 dictionary += dictLength - s->w_size; /* use the tail */ 405 dictLength = s->w_size; 406 } 407 408 /* insert dictionary into window and hash */ 409 avail = strm->avail_in; 410 next = strm->next_in; 411 strm->avail_in = dictLength; 412 strm->next_in = (z_const Bytef *)dictionary; 413 fill_window(s); 414 while (s->lookahead >= MIN_MATCH) { 415 str = s->strstart; 416 n = s->lookahead - (MIN_MATCH-1); 417 do { 418 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 419 #ifndef FASTEST 420 s->prev[str & s->w_mask] = s->head[s->ins_h]; 421 #endif 422 s->head[s->ins_h] = (Pos)str; 423 str++; 424 } while (--n); 425 s->strstart = str; 426 s->lookahead = MIN_MATCH-1; 427 fill_window(s); 428 } 429 s->strstart += s->lookahead; 430 s->block_start = (long)s->strstart; 431 s->insert = s->lookahead; 432 s->lookahead = 0; 433 s->match_length = s->prev_length = MIN_MATCH-1; 434 s->match_available = 0; 435 strm->next_in = next; 436 strm->avail_in = avail; 437 s->wrap = wrap; 438 return Z_OK; 439 } 440 441 /* ========================================================================= */ 442 int ZEXPORT deflateGetDictionary (strm, dictionary, dictLength) 443 z_streamp strm; 444 Bytef *dictionary; 445 uInt *dictLength; 446 { 447 deflate_state *s; 448 uInt len; 449 450 if (deflateStateCheck(strm)) 451 return Z_STREAM_ERROR; 452 s = strm->state; 453 len = s->strstart + s->lookahead; 454 if (len > s->w_size) 455 len = s->w_size; 456 if (dictionary != Z_NULL && len) 457 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len); 458 if (dictLength != Z_NULL) 459 *dictLength = len; 460 return Z_OK; 461 } 462 463 /* ========================================================================= */ 464 int ZEXPORT deflateResetKeep (strm) 465 z_streamp strm; 466 { 467 deflate_state *s; 468 469 if (deflateStateCheck(strm)) { 470 return Z_STREAM_ERROR; 471 } 472 473 strm->total_in = strm->total_out = 0; 474 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 475 strm->data_type = Z_UNKNOWN; 476 477 s = (deflate_state *)strm->state; 478 s->pending = 0; 479 s->pending_out = s->pending_buf; 480 481 if (s->wrap < 0) { 482 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 483 } 484 s->status = 485 #ifdef GZIP 486 s->wrap == 2 ? GZIP_STATE : 487 #endif 488 s->wrap ? INIT_STATE : BUSY_STATE; 489 strm->adler = 490 #ifdef GZIP 491 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 492 #endif 493 adler32(0L, Z_NULL, 0); 494 s->last_flush = Z_NO_FLUSH; 495 496 _tr_init(s); 497 498 return Z_OK; 499 } 500 501 /* ========================================================================= */ 502 int ZEXPORT deflateReset (strm) 503 z_streamp strm; 504 { 505 int ret; 506 507 ret = deflateResetKeep(strm); 508 if (ret == Z_OK) 509 lm_init(strm->state); 510 return ret; 511 } 512 513 /* ========================================================================= */ 514 int ZEXPORT deflateSetHeader (strm, head) 515 z_streamp strm; 516 gz_headerp head; 517 { 518 if (deflateStateCheck(strm) || strm->state->wrap != 2) 519 return Z_STREAM_ERROR; 520 strm->state->gzhead = head; 521 return Z_OK; 522 } 523 524 /* ========================================================================= */ 525 int ZEXPORT deflatePending (strm, pending, bits) 526 unsigned *pending; 527 int *bits; 528 z_streamp strm; 529 { 530 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 531 if (pending != Z_NULL) 532 *pending = strm->state->pending; 533 if (bits != Z_NULL) 534 *bits = strm->state->bi_valid; 535 return Z_OK; 536 } 537 538 /* ========================================================================= */ 539 int ZEXPORT deflatePrime (strm, bits, value) 540 z_streamp strm; 541 int bits; 542 int value; 543 { 544 deflate_state *s; 545 int put; 546 547 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 548 s = strm->state; 549 if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3)) 550 return Z_BUF_ERROR; 551 do { 552 put = Buf_size - s->bi_valid; 553 if (put > bits) 554 put = bits; 555 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); 556 s->bi_valid += put; 557 _tr_flush_bits(s); 558 value >>= put; 559 bits -= put; 560 } while (bits); 561 return Z_OK; 562 } 563 564 /* ========================================================================= */ 565 int ZEXPORT deflateParams(strm, level, strategy) 566 z_streamp strm; 567 int level; 568 int strategy; 569 { 570 deflate_state *s; 571 compress_func func; 572 573 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 574 s = strm->state; 575 576 #ifdef FASTEST 577 if (level != 0) level = 1; 578 #else 579 if (level == Z_DEFAULT_COMPRESSION) level = 6; 580 #endif 581 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 582 return Z_STREAM_ERROR; 583 } 584 func = configuration_table[s->level].func; 585 586 if ((strategy != s->strategy || func != configuration_table[level].func) && 587 s->high_water) { 588 /* Flush the last buffer: */ 589 int err = deflate(strm, Z_BLOCK); 590 if (err == Z_STREAM_ERROR) 591 return err; 592 if (strm->avail_out == 0) 593 return Z_BUF_ERROR; 594 } 595 if (s->level != level) { 596 if (s->level == 0 && s->matches != 0) { 597 if (s->matches == 1) 598 slide_hash(s); 599 else 600 CLEAR_HASH(s); 601 s->matches = 0; 602 } 603 s->level = level; 604 s->max_lazy_match = configuration_table[level].max_lazy; 605 s->good_match = configuration_table[level].good_length; 606 s->nice_match = configuration_table[level].nice_length; 607 s->max_chain_length = configuration_table[level].max_chain; 608 } 609 s->strategy = strategy; 610 return Z_OK; 611 } 612 613 /* ========================================================================= */ 614 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain) 615 z_streamp strm; 616 int good_length; 617 int max_lazy; 618 int nice_length; 619 int max_chain; 620 { 621 deflate_state *s; 622 623 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 624 s = strm->state; 625 s->good_match = (uInt)good_length; 626 s->max_lazy_match = (uInt)max_lazy; 627 s->nice_match = nice_length; 628 s->max_chain_length = (uInt)max_chain; 629 return Z_OK; 630 } 631 632 /* ========================================================================= 633 * For the default windowBits of 15 and memLevel of 8, this function returns 634 * a close to exact, as well as small, upper bound on the compressed size. 635 * They are coded as constants here for a reason--if the #define's are 636 * changed, then this function needs to be changed as well. The return 637 * value for 15 and 8 only works for those exact settings. 638 * 639 * For any setting other than those defaults for windowBits and memLevel, 640 * the value returned is a conservative worst case for the maximum expansion 641 * resulting from using fixed blocks instead of stored blocks, which deflate 642 * can emit on compressed data for some combinations of the parameters. 643 * 644 * This function could be more sophisticated to provide closer upper bounds for 645 * every combination of windowBits and memLevel. But even the conservative 646 * upper bound of about 14% expansion does not seem onerous for output buffer 647 * allocation. 648 */ 649 uLong ZEXPORT deflateBound(strm, sourceLen) 650 z_streamp strm; 651 uLong sourceLen; 652 { 653 deflate_state *s; 654 uLong complen, wraplen; 655 656 /* conservative upper bound for compressed data */ 657 complen = sourceLen + 658 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5; 659 660 /* if can't get parameters, return conservative bound plus zlib wrapper */ 661 if (deflateStateCheck(strm)) 662 return complen + 6; 663 664 /* compute wrapper length */ 665 s = strm->state; 666 switch (s->wrap) { 667 case 0: /* raw deflate */ 668 wraplen = 0; 669 break; 670 case 1: /* zlib wrapper */ 671 wraplen = 6 + (s->strstart ? 4 : 0); 672 break; 673 #ifdef GZIP 674 case 2: /* gzip wrapper */ 675 wraplen = 18; 676 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 677 Bytef *str; 678 if (s->gzhead->extra != Z_NULL) 679 wraplen += 2 + s->gzhead->extra_len; 680 str = s->gzhead->name; 681 if (str != Z_NULL) 682 do { 683 wraplen++; 684 } while (*str++); 685 str = s->gzhead->comment; 686 if (str != Z_NULL) 687 do { 688 wraplen++; 689 } while (*str++); 690 if (s->gzhead->hcrc) 691 wraplen += 2; 692 } 693 break; 694 #endif 695 default: /* for compiler happiness */ 696 wraplen = 6; 697 } 698 699 /* if not default parameters, return conservative bound */ 700 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 701 return complen + wraplen; 702 703 /* default settings: return tight bound for that case */ 704 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 705 (sourceLen >> 25) + 13 - 6 + wraplen; 706 } 707 708 /* ========================================================================= 709 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 710 * IN assertion: the stream state is correct and there is enough room in 711 * pending_buf. 712 */ 713 local void putShortMSB (s, b) 714 deflate_state *s; 715 uInt b; 716 { 717 put_byte(s, (Byte)(b >> 8)); 718 put_byte(s, (Byte)(b & 0xff)); 719 } 720 721 /* ========================================================================= 722 * Flush as much pending output as possible. All deflate() output, except for 723 * some deflate_stored() output, goes through this function so some 724 * applications may wish to modify it to avoid allocating a large 725 * strm->next_out buffer and copying into it. (See also read_buf()). 726 */ 727 local void flush_pending(strm) 728 z_streamp strm; 729 { 730 unsigned len; 731 deflate_state *s = strm->state; 732 733 _tr_flush_bits(s); 734 len = s->pending; 735 if (len > strm->avail_out) len = strm->avail_out; 736 if (len == 0) return; 737 738 zmemcpy(strm->next_out, s->pending_out, len); 739 strm->next_out += len; 740 s->pending_out += len; 741 strm->total_out += len; 742 strm->avail_out -= len; 743 s->pending -= len; 744 if (s->pending == 0) { 745 s->pending_out = s->pending_buf; 746 } 747 } 748 749 /* =========================================================================== 750 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1]. 751 */ 752 #define HCRC_UPDATE(beg) \ 753 do { \ 754 if (s->gzhead->hcrc && s->pending > (beg)) \ 755 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \ 756 s->pending - (beg)); \ 757 } while (0) 758 759 /* ========================================================================= */ 760 int ZEXPORT deflate (strm, flush) 761 z_streamp strm; 762 int flush; 763 { 764 int old_flush; /* value of flush param for previous deflate call */ 765 deflate_state *s; 766 767 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { 768 return Z_STREAM_ERROR; 769 } 770 s = strm->state; 771 772 if (strm->next_out == Z_NULL || 773 (strm->avail_in != 0 && strm->next_in == Z_NULL) || 774 (s->status == FINISH_STATE && flush != Z_FINISH)) { 775 ERR_RETURN(strm, Z_STREAM_ERROR); 776 } 777 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 778 779 old_flush = s->last_flush; 780 s->last_flush = flush; 781 782 /* Flush as much pending output as possible */ 783 if (s->pending != 0) { 784 flush_pending(strm); 785 if (strm->avail_out == 0) { 786 /* Since avail_out is 0, deflate will be called again with 787 * more output space, but possibly with both pending and 788 * avail_in equal to zero. There won't be anything to do, 789 * but this is not an error situation so make sure we 790 * return OK instead of BUF_ERROR at next call of deflate: 791 */ 792 s->last_flush = -1; 793 return Z_OK; 794 } 795 796 /* Make sure there is something to do and avoid duplicate consecutive 797 * flushes. For repeated and useless calls with Z_FINISH, we keep 798 * returning Z_STREAM_END instead of Z_BUF_ERROR. 799 */ 800 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 801 flush != Z_FINISH) { 802 ERR_RETURN(strm, Z_BUF_ERROR); 803 } 804 805 /* User must not provide more input after the first FINISH: */ 806 if (s->status == FINISH_STATE && strm->avail_in != 0) { 807 ERR_RETURN(strm, Z_BUF_ERROR); 808 } 809 810 /* Write the header */ 811 if (s->status == INIT_STATE) { 812 /* zlib header */ 813 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; 814 uInt level_flags; 815 816 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 817 level_flags = 0; 818 else if (s->level < 6) 819 level_flags = 1; 820 else if (s->level == 6) 821 level_flags = 2; 822 else 823 level_flags = 3; 824 header |= (level_flags << 6); 825 if (s->strstart != 0) header |= PRESET_DICT; 826 header += 31 - (header % 31); 827 828 putShortMSB(s, header); 829 830 /* Save the adler32 of the preset dictionary: */ 831 if (s->strstart != 0) { 832 putShortMSB(s, (uInt)(strm->adler >> 16)); 833 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 834 } 835 strm->adler = adler32(0L, Z_NULL, 0); 836 s->status = BUSY_STATE; 837 838 /* Compression must start with an empty pending buffer */ 839 flush_pending(strm); 840 if (s->pending != 0) { 841 s->last_flush = -1; 842 return Z_OK; 843 } 844 } 845 #ifdef GZIP 846 if (s->status == GZIP_STATE) { 847 /* gzip header */ 848 strm->adler = crc32(0L, Z_NULL, 0); 849 put_byte(s, 31); 850 put_byte(s, 139); 851 put_byte(s, 8); 852 if (s->gzhead == Z_NULL) { 853 put_byte(s, 0); 854 put_byte(s, 0); 855 put_byte(s, 0); 856 put_byte(s, 0); 857 put_byte(s, 0); 858 put_byte(s, s->level == 9 ? 2 : 859 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 860 4 : 0)); 861 put_byte(s, OS_CODE); 862 s->status = BUSY_STATE; 863 864 /* Compression must start with an empty pending buffer */ 865 flush_pending(strm); 866 if (s->pending != 0) { 867 s->last_flush = -1; 868 return Z_OK; 869 } 870 } 871 else { 872 put_byte(s, (s->gzhead->text ? 1 : 0) + 873 (s->gzhead->hcrc ? 2 : 0) + 874 (s->gzhead->extra == Z_NULL ? 0 : 4) + 875 (s->gzhead->name == Z_NULL ? 0 : 8) + 876 (s->gzhead->comment == Z_NULL ? 0 : 16) 877 ); 878 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 879 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 880 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 881 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 882 put_byte(s, s->level == 9 ? 2 : 883 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 884 4 : 0)); 885 put_byte(s, s->gzhead->os & 0xff); 886 if (s->gzhead->extra != Z_NULL) { 887 put_byte(s, s->gzhead->extra_len & 0xff); 888 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 889 } 890 if (s->gzhead->hcrc) 891 strm->adler = crc32(strm->adler, s->pending_buf, 892 s->pending); 893 s->gzindex = 0; 894 s->status = EXTRA_STATE; 895 } 896 } 897 if (s->status == EXTRA_STATE) { 898 if (s->gzhead->extra != Z_NULL) { 899 ulg beg = s->pending; /* start of bytes to update crc */ 900 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex; 901 while (s->pending + left > s->pending_buf_size) { 902 uInt copy = s->pending_buf_size - s->pending; 903 zmemcpy(s->pending_buf + s->pending, 904 s->gzhead->extra + s->gzindex, copy); 905 s->pending = s->pending_buf_size; 906 HCRC_UPDATE(beg); 907 s->gzindex += copy; 908 flush_pending(strm); 909 if (s->pending != 0) { 910 s->last_flush = -1; 911 return Z_OK; 912 } 913 beg = 0; 914 left -= copy; 915 } 916 zmemcpy(s->pending_buf + s->pending, 917 s->gzhead->extra + s->gzindex, left); 918 s->pending += left; 919 HCRC_UPDATE(beg); 920 s->gzindex = 0; 921 } 922 s->status = NAME_STATE; 923 } 924 if (s->status == NAME_STATE) { 925 if (s->gzhead->name != Z_NULL) { 926 ulg beg = s->pending; /* start of bytes to update crc */ 927 int val; 928 do { 929 if (s->pending == s->pending_buf_size) { 930 HCRC_UPDATE(beg); 931 flush_pending(strm); 932 if (s->pending != 0) { 933 s->last_flush = -1; 934 return Z_OK; 935 } 936 beg = 0; 937 } 938 val = s->gzhead->name[s->gzindex++]; 939 put_byte(s, val); 940 } while (val != 0); 941 HCRC_UPDATE(beg); 942 s->gzindex = 0; 943 } 944 s->status = COMMENT_STATE; 945 } 946 if (s->status == COMMENT_STATE) { 947 if (s->gzhead->comment != Z_NULL) { 948 ulg beg = s->pending; /* start of bytes to update crc */ 949 int val; 950 do { 951 if (s->pending == s->pending_buf_size) { 952 HCRC_UPDATE(beg); 953 flush_pending(strm); 954 if (s->pending != 0) { 955 s->last_flush = -1; 956 return Z_OK; 957 } 958 beg = 0; 959 } 960 val = s->gzhead->comment[s->gzindex++]; 961 put_byte(s, val); 962 } while (val != 0); 963 HCRC_UPDATE(beg); 964 } 965 s->status = HCRC_STATE; 966 } 967 if (s->status == HCRC_STATE) { 968 if (s->gzhead->hcrc) { 969 if (s->pending + 2 > s->pending_buf_size) { 970 flush_pending(strm); 971 if (s->pending != 0) { 972 s->last_flush = -1; 973 return Z_OK; 974 } 975 } 976 put_byte(s, (Byte)(strm->adler & 0xff)); 977 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 978 strm->adler = crc32(0L, Z_NULL, 0); 979 } 980 s->status = BUSY_STATE; 981 982 /* Compression must start with an empty pending buffer */ 983 flush_pending(strm); 984 if (s->pending != 0) { 985 s->last_flush = -1; 986 return Z_OK; 987 } 988 } 989 #endif 990 991 /* Start a new block or continue the current one. 992 */ 993 if (strm->avail_in != 0 || s->lookahead != 0 || 994 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 995 block_state bstate; 996 997 bstate = s->level == 0 ? deflate_stored(s, flush) : 998 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 999 s->strategy == Z_RLE ? deflate_rle(s, flush) : 1000 (*(configuration_table[s->level].func))(s, flush); 1001 1002 if (bstate == finish_started || bstate == finish_done) { 1003 s->status = FINISH_STATE; 1004 } 1005 if (bstate == need_more || bstate == finish_started) { 1006 if (strm->avail_out == 0) { 1007 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 1008 } 1009 return Z_OK; 1010 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 1011 * of deflate should use the same flush parameter to make sure 1012 * that the flush is complete. So we don't have to output an 1013 * empty block here, this will be done at next call. This also 1014 * ensures that for a very small output buffer, we emit at most 1015 * one empty block. 1016 */ 1017 } 1018 if (bstate == block_done) { 1019 if (flush == Z_PARTIAL_FLUSH) { 1020 _tr_align(s); 1021 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 1022 _tr_stored_block(s, (char*)0, 0L, 0); 1023 /* For a full flush, this empty block will be recognized 1024 * as a special marker by inflate_sync(). 1025 */ 1026 if (flush == Z_FULL_FLUSH) { 1027 CLEAR_HASH(s); /* forget history */ 1028 if (s->lookahead == 0) { 1029 s->strstart = 0; 1030 s->block_start = 0L; 1031 s->insert = 0; 1032 } 1033 } 1034 } 1035 flush_pending(strm); 1036 if (strm->avail_out == 0) { 1037 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 1038 return Z_OK; 1039 } 1040 } 1041 } 1042 1043 if (flush != Z_FINISH) return Z_OK; 1044 if (s->wrap <= 0) return Z_STREAM_END; 1045 1046 /* Write the trailer */ 1047 #ifdef GZIP 1048 if (s->wrap == 2) { 1049 put_byte(s, (Byte)(strm->adler & 0xff)); 1050 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1051 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 1052 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 1053 put_byte(s, (Byte)(strm->total_in & 0xff)); 1054 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 1055 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 1056 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 1057 } 1058 else 1059 #endif 1060 { 1061 putShortMSB(s, (uInt)(strm->adler >> 16)); 1062 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1063 } 1064 flush_pending(strm); 1065 /* If avail_out is zero, the application will call deflate again 1066 * to flush the rest. 1067 */ 1068 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 1069 return s->pending != 0 ? Z_OK : Z_STREAM_END; 1070 } 1071 1072 /* ========================================================================= */ 1073 int ZEXPORT deflateEnd (strm) 1074 z_streamp strm; 1075 { 1076 int status; 1077 1078 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 1079 1080 status = strm->state->status; 1081 1082 /* Deallocate in reverse order of allocations: */ 1083 TRY_FREE(strm, strm->state->pending_buf, strm->state->pending_buf_size); 1084 TRY_FREE(strm, strm->state->head, strm->state->hash_size * sizeof(Pos)); 1085 TRY_FREE(strm, strm->state->prev, strm->state->w_size * sizeof(Pos)); 1086 TRY_FREE(strm, strm->state->window, strm->state->w_size * 2 * sizeof(Byte)); 1087 1088 ZFREE(strm, strm->state, sizeof(deflate_state)); 1089 strm->state = Z_NULL; 1090 1091 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1092 } 1093 1094 /* ========================================================================= 1095 * Copy the source state to the destination state. 1096 * To simplify the source, this is not supported for 16-bit MSDOS (which 1097 * doesn't have enough memory anyway to duplicate compression states). 1098 */ 1099 int ZEXPORT deflateCopy (dest, source) 1100 z_streamp dest; 1101 z_streamp source; 1102 { 1103 #ifdef MAXSEG_64K 1104 return Z_STREAM_ERROR; 1105 #else 1106 deflate_state *ds; 1107 deflate_state *ss; 1108 ushf *overlay; 1109 1110 1111 if (deflateStateCheck(source) || dest == Z_NULL) { 1112 return Z_STREAM_ERROR; 1113 } 1114 1115 ss = source->state; 1116 1117 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream)); 1118 1119 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1120 if (ds == Z_NULL) return Z_MEM_ERROR; 1121 dest->state = (struct internal_state FAR *) ds; 1122 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state)); 1123 ds->strm = dest; 1124 1125 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1126 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1127 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1128 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); 1129 ds->pending_buf = (uchf *) overlay; 1130 1131 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1132 ds->pending_buf == Z_NULL) { 1133 deflateEnd (dest); 1134 return Z_MEM_ERROR; 1135 } 1136 /* following zmemcpy do not work for 16-bit MSDOS */ 1137 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1138 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos)); 1139 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos)); 1140 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); 1141 1142 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1143 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); 1144 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; 1145 1146 ds->l_desc.dyn_tree = ds->dyn_ltree; 1147 ds->d_desc.dyn_tree = ds->dyn_dtree; 1148 ds->bl_desc.dyn_tree = ds->bl_tree; 1149 1150 return Z_OK; 1151 #endif /* MAXSEG_64K */ 1152 } 1153 1154 /* =========================================================================== 1155 * Read a new buffer from the current input stream, update the adler32 1156 * and total number of bytes read. All deflate() input goes through 1157 * this function so some applications may wish to modify it to avoid 1158 * allocating a large strm->next_in buffer and copying from it. 1159 * (See also flush_pending()). 1160 */ 1161 local unsigned read_buf(strm, buf, size) 1162 z_streamp strm; 1163 Bytef *buf; 1164 unsigned size; 1165 { 1166 unsigned len = strm->avail_in; 1167 1168 if (len > size) len = size; 1169 if (len == 0) return 0; 1170 1171 strm->avail_in -= len; 1172 1173 zmemcpy(buf, strm->next_in, len); 1174 if (strm->state->wrap == 1) { 1175 strm->adler = adler32(strm->adler, buf, len); 1176 } 1177 #ifdef GZIP 1178 else if (strm->state->wrap == 2) { 1179 strm->adler = crc32(strm->adler, buf, len); 1180 } 1181 #endif 1182 strm->next_in += len; 1183 strm->total_in += len; 1184 1185 return len; 1186 } 1187 1188 /* =========================================================================== 1189 * Initialize the "longest match" routines for a new zlib stream 1190 */ 1191 local void lm_init (s) 1192 deflate_state *s; 1193 { 1194 s->window_size = (ulg)2L*s->w_size; 1195 1196 CLEAR_HASH(s); 1197 1198 /* Set the default configuration parameters: 1199 */ 1200 s->max_lazy_match = configuration_table[s->level].max_lazy; 1201 s->good_match = configuration_table[s->level].good_length; 1202 s->nice_match = configuration_table[s->level].nice_length; 1203 s->max_chain_length = configuration_table[s->level].max_chain; 1204 1205 s->strstart = 0; 1206 s->block_start = 0L; 1207 s->lookahead = 0; 1208 s->insert = 0; 1209 s->match_length = s->prev_length = MIN_MATCH-1; 1210 s->match_available = 0; 1211 s->ins_h = 0; 1212 #ifndef FASTEST 1213 #ifdef ASMV 1214 match_init(); /* initialize the asm code */ 1215 #endif 1216 #endif 1217 } 1218 1219 #ifndef FASTEST 1220 /* =========================================================================== 1221 * Set match_start to the longest match starting at the given string and 1222 * return its length. Matches shorter or equal to prev_length are discarded, 1223 * in which case the result is equal to prev_length and match_start is 1224 * garbage. 1225 * IN assertions: cur_match is the head of the hash chain for the current 1226 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1227 * OUT assertion: the match length is not greater than s->lookahead. 1228 */ 1229 #ifndef ASMV 1230 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or 1231 * match.S. The code will be functionally equivalent. 1232 */ 1233 local uInt longest_match(s, cur_match) 1234 deflate_state *s; 1235 IPos cur_match; /* current match */ 1236 { 1237 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1238 register Bytef *scan = s->window + s->strstart; /* current string */ 1239 register Bytef *match; /* matched string */ 1240 register int len; /* length of current match */ 1241 int best_len = (int)s->prev_length; /* best match length so far */ 1242 int nice_match = s->nice_match; /* stop if match long enough */ 1243 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1244 s->strstart - (IPos)MAX_DIST(s) : NIL; 1245 /* Stop when cur_match becomes <= limit. To simplify the code, 1246 * we prevent matches with the string of window index 0. 1247 */ 1248 Posf *prev = s->prev; 1249 uInt wmask = s->w_mask; 1250 1251 #ifdef UNALIGNED_OK 1252 /* Compare two bytes at a time. Note: this is not always beneficial. 1253 * Try with and without -DUNALIGNED_OK to check. 1254 */ 1255 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1256 register ush scan_start = *(ushf*)scan; 1257 register ush scan_end = *(ushf*)(scan+best_len-1); 1258 #else 1259 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1260 register Byte scan_end1 = scan[best_len-1]; 1261 register Byte scan_end = scan[best_len]; 1262 #endif 1263 1264 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1265 * It is easy to get rid of this optimization if necessary. 1266 */ 1267 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1268 1269 /* Do not waste too much time if we already have a good match: */ 1270 if (s->prev_length >= s->good_match) { 1271 chain_length >>= 2; 1272 } 1273 /* Do not look for matches beyond the end of the input. This is necessary 1274 * to make deflate deterministic. 1275 */ 1276 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead; 1277 1278 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1279 1280 do { 1281 Assert(cur_match < s->strstart, "no future"); 1282 match = s->window + cur_match; 1283 1284 /* Skip to next match if the match length cannot increase 1285 * or if the match length is less than 2. Note that the checks below 1286 * for insufficient lookahead only occur occasionally for performance 1287 * reasons. Therefore uninitialized memory will be accessed, and 1288 * conditional jumps will be made that depend on those values. 1289 * However the length of the match is limited to the lookahead, so 1290 * the output of deflate is not affected by the uninitialized values. 1291 */ 1292 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1293 /* This code assumes sizeof(unsigned short) == 2. Do not use 1294 * UNALIGNED_OK if your compiler uses a different size. 1295 */ 1296 if (*(ushf*)(match+best_len-1) != scan_end || 1297 *(ushf*)match != scan_start) continue; 1298 1299 /* It is not necessary to compare scan[2] and match[2] since they are 1300 * always equal when the other bytes match, given that the hash keys 1301 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1302 * strstart+3, +5, ... up to strstart+257. We check for insufficient 1303 * lookahead only every 4th comparison; the 128th check will be made 1304 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is 1305 * necessary to put more guard bytes at the end of the window, or 1306 * to check more often for insufficient lookahead. 1307 */ 1308 Assert(scan[2] == match[2], "scan[2]?"); 1309 scan++, match++; 1310 do { 1311 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1312 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1313 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1314 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1315 scan < strend); 1316 /* The funny "do {}" generates better code on most compilers */ 1317 1318 /* Here, scan <= window+strstart+257 */ 1319 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1320 if (*scan == *match) scan++; 1321 1322 len = (MAX_MATCH - 1) - (int)(strend-scan); 1323 scan = strend - (MAX_MATCH-1); 1324 1325 #else /* UNALIGNED_OK */ 1326 1327 if (match[best_len] != scan_end || 1328 match[best_len-1] != scan_end1 || 1329 *match != *scan || 1330 *++match != scan[1]) continue; 1331 1332 /* The check at best_len-1 can be removed because it will be made 1333 * again later. (This heuristic is not always a win.) 1334 * It is not necessary to compare scan[2] and match[2] since they 1335 * are always equal when the other bytes match, given that 1336 * the hash keys are equal and that HASH_BITS >= 8. 1337 */ 1338 scan += 2, match++; 1339 Assert(*scan == *match, "match[2]?"); 1340 1341 /* We check for insufficient lookahead only every 8th comparison; 1342 * the 256th check will be made at strstart+258. 1343 */ 1344 do { 1345 } while (*++scan == *++match && *++scan == *++match && 1346 *++scan == *++match && *++scan == *++match && 1347 *++scan == *++match && *++scan == *++match && 1348 *++scan == *++match && *++scan == *++match && 1349 scan < strend); 1350 1351 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1352 1353 len = MAX_MATCH - (int)(strend - scan); 1354 scan = strend - MAX_MATCH; 1355 1356 #endif /* UNALIGNED_OK */ 1357 1358 if (len > best_len) { 1359 s->match_start = cur_match; 1360 best_len = len; 1361 if (len >= nice_match) break; 1362 #ifdef UNALIGNED_OK 1363 scan_end = *(ushf*)(scan+best_len-1); 1364 #else 1365 scan_end1 = scan[best_len-1]; 1366 scan_end = scan[best_len]; 1367 #endif 1368 } 1369 } while ((cur_match = prev[cur_match & wmask]) > limit 1370 && --chain_length != 0); 1371 1372 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1373 return s->lookahead; 1374 } 1375 #endif /* ASMV */ 1376 1377 #else /* FASTEST */ 1378 1379 /* --------------------------------------------------------------------------- 1380 * Optimized version for FASTEST only 1381 */ 1382 local uInt longest_match(s, cur_match) 1383 deflate_state *s; 1384 IPos cur_match; /* current match */ 1385 { 1386 register Bytef *scan = s->window + s->strstart; /* current string */ 1387 register Bytef *match; /* matched string */ 1388 register int len; /* length of current match */ 1389 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1390 1391 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1392 * It is easy to get rid of this optimization if necessary. 1393 */ 1394 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1395 1396 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1397 1398 Assert(cur_match < s->strstart, "no future"); 1399 1400 match = s->window + cur_match; 1401 1402 /* Return failure if the match length is less than 2: 1403 */ 1404 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1405 1406 /* The check at best_len-1 can be removed because it will be made 1407 * again later. (This heuristic is not always a win.) 1408 * It is not necessary to compare scan[2] and match[2] since they 1409 * are always equal when the other bytes match, given that 1410 * the hash keys are equal and that HASH_BITS >= 8. 1411 */ 1412 scan += 2, match += 2; 1413 Assert(*scan == *match, "match[2]?"); 1414 1415 /* We check for insufficient lookahead only every 8th comparison; 1416 * the 256th check will be made at strstart+258. 1417 */ 1418 do { 1419 } while (*++scan == *++match && *++scan == *++match && 1420 *++scan == *++match && *++scan == *++match && 1421 *++scan == *++match && *++scan == *++match && 1422 *++scan == *++match && *++scan == *++match && 1423 scan < strend); 1424 1425 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1426 1427 len = MAX_MATCH - (int)(strend - scan); 1428 1429 if (len < MIN_MATCH) return MIN_MATCH - 1; 1430 1431 s->match_start = cur_match; 1432 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1433 } 1434 1435 #endif /* FASTEST */ 1436 1437 #ifdef ZLIB_DEBUG 1438 1439 #define EQUAL 0 1440 /* result of memcmp for equal strings */ 1441 1442 /* =========================================================================== 1443 * Check that the match at match_start is indeed a match. 1444 */ 1445 local void check_match(s, start, match, length) 1446 deflate_state *s; 1447 IPos start, match; 1448 int length; 1449 { 1450 /* check that the match is indeed a match */ 1451 if (zmemcmp(s->window + match, 1452 s->window + start, length) != EQUAL) { 1453 fprintf(stderr, " start %u, match %u, length %d\n", 1454 start, match, length); 1455 do { 1456 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); 1457 } while (--length != 0); 1458 z_error("invalid match"); 1459 } 1460 if (z_verbose > 1) { 1461 fprintf(stderr,"\\[%d,%d]", start-match, length); 1462 do { putc(s->window[start++], stderr); } while (--length != 0); 1463 } 1464 } 1465 #else 1466 # define check_match(s, start, match, length) 1467 #endif /* ZLIB_DEBUG */ 1468 1469 /* =========================================================================== 1470 * Fill the window when the lookahead becomes insufficient. 1471 * Updates strstart and lookahead. 1472 * 1473 * IN assertion: lookahead < MIN_LOOKAHEAD 1474 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 1475 * At least one byte has been read, or avail_in == 0; reads are 1476 * performed for at least two bytes (required for the zip translate_eol 1477 * option -- not supported here). 1478 */ 1479 local void fill_window(s) 1480 deflate_state *s; 1481 { 1482 unsigned n; 1483 unsigned more; /* Amount of free space at the end of the window. */ 1484 uInt wsize = s->w_size; 1485 1486 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); 1487 1488 do { 1489 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 1490 1491 /* Deal with !@#$% 64K limit: */ 1492 if (sizeof(int) <= 2) { 1493 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 1494 more = wsize; 1495 1496 } else if (more == (unsigned)(-1)) { 1497 /* Very unlikely, but possible on 16 bit machine if 1498 * strstart == 0 && lookahead == 1 (input done a byte at time) 1499 */ 1500 more--; 1501 } 1502 } 1503 1504 /* If the window is almost full and there is insufficient lookahead, 1505 * move the upper half to the lower one to make room in the upper half. 1506 */ 1507 if (s->strstart >= wsize+MAX_DIST(s)) { 1508 1509 zmemcpy(s->window, s->window+wsize, (unsigned)wsize - more); 1510 s->match_start -= wsize; 1511 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 1512 s->block_start -= (long) wsize; 1513 slide_hash(s); 1514 more += wsize; 1515 } 1516 if (s->strm->avail_in == 0) break; 1517 1518 /* If there was no sliding: 1519 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 1520 * more == window_size - lookahead - strstart 1521 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 1522 * => more >= window_size - 2*WSIZE + 2 1523 * In the BIG_MEM or MMAP case (not yet supported), 1524 * window_size == input_size + MIN_LOOKAHEAD && 1525 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 1526 * Otherwise, window_size == 2*WSIZE so more >= 2. 1527 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 1528 */ 1529 Assert(more >= 2, "more < 2"); 1530 1531 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 1532 s->lookahead += n; 1533 1534 /* Initialize the hash value now that we have some input: */ 1535 if (s->lookahead + s->insert >= MIN_MATCH) { 1536 uInt str = s->strstart - s->insert; 1537 s->ins_h = s->window[str]; 1538 UPDATE_HASH(s, s->ins_h, s->window[str + 1]); 1539 #if MIN_MATCH != 3 1540 Call UPDATE_HASH() MIN_MATCH-3 more times 1541 #endif 1542 while (s->insert) { 1543 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 1544 #ifndef FASTEST 1545 s->prev[str & s->w_mask] = s->head[s->ins_h]; 1546 #endif 1547 s->head[s->ins_h] = (Pos)str; 1548 str++; 1549 s->insert--; 1550 if (s->lookahead + s->insert < MIN_MATCH) 1551 break; 1552 } 1553 } 1554 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 1555 * but this is not important since only literal bytes will be emitted. 1556 */ 1557 1558 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 1559 1560 /* If the WIN_INIT bytes after the end of the current data have never been 1561 * written, then zero those bytes in order to avoid memory check reports of 1562 * the use of uninitialized (or uninitialised as Julian writes) bytes by 1563 * the longest match routines. Update the high water mark for the next 1564 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 1565 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 1566 */ 1567 if (s->high_water < s->window_size) { 1568 ulg curr = s->strstart + (ulg)(s->lookahead); 1569 ulg init; 1570 1571 if (s->high_water < curr) { 1572 /* Previous high water mark below current data -- zero WIN_INIT 1573 * bytes or up to end of window, whichever is less. 1574 */ 1575 init = s->window_size - curr; 1576 if (init > WIN_INIT) 1577 init = WIN_INIT; 1578 zmemzero(s->window + curr, (unsigned)init); 1579 s->high_water = curr + init; 1580 } 1581 else if (s->high_water < (ulg)curr + WIN_INIT) { 1582 /* High water mark at or above current data, but below current data 1583 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 1584 * to end of window, whichever is less. 1585 */ 1586 init = (ulg)curr + WIN_INIT - s->high_water; 1587 if (init > s->window_size - s->high_water) 1588 init = s->window_size - s->high_water; 1589 zmemzero(s->window + s->high_water, (unsigned)init); 1590 s->high_water += init; 1591 } 1592 } 1593 1594 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1595 "not enough room for search"); 1596 } 1597 1598 /* =========================================================================== 1599 * Flush the current block, with given end-of-file flag. 1600 * IN assertion: strstart is set to the end of the current match. 1601 */ 1602 #define FLUSH_BLOCK_ONLY(s, last) { \ 1603 _tr_flush_block(s, (s->block_start >= 0L ? \ 1604 (charf *)&s->window[(unsigned)s->block_start] : \ 1605 (charf *)Z_NULL), \ 1606 (ulg)((long)s->strstart - s->block_start), \ 1607 (last)); \ 1608 s->block_start = s->strstart; \ 1609 flush_pending(s->strm); \ 1610 Tracev((stderr,"[FLUSH]")); \ 1611 } 1612 1613 /* Same but force premature exit if necessary. */ 1614 #define FLUSH_BLOCK(s, last) { \ 1615 FLUSH_BLOCK_ONLY(s, last); \ 1616 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1617 } 1618 1619 /* Maximum stored block length in deflate format (not including header). */ 1620 #define MAX_STORED 65535 1621 1622 #ifndef MIN 1623 /* Minimum of a and b. */ 1624 #define MIN(a, b) ((a) > (b) ? (b) : (a)) 1625 #endif 1626 1627 /* =========================================================================== 1628 * Copy without compression as much as possible from the input stream, return 1629 * the current block state. 1630 * 1631 * In case deflateParams() is used to later switch to a non-zero compression 1632 * level, s->matches (otherwise unused when storing) keeps track of the number 1633 * of hash table slides to perform. If s->matches is 1, then one hash table 1634 * slide will be done when switching. If s->matches is 2, the maximum value 1635 * allowed here, then the hash table will be cleared, since two or more slides 1636 * is the same as a clear. 1637 * 1638 * deflate_stored() is written to minimize the number of times an input byte is 1639 * copied. It is most efficient with large input and output buffers, which 1640 * maximizes the opportunites to have a single copy from next_in to next_out. 1641 */ 1642 local block_state deflate_stored(s, flush) 1643 deflate_state *s; 1644 int flush; 1645 { 1646 /* Smallest worthy block size when not flushing or finishing. By default 1647 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For 1648 * large input and output buffers, the stored block size will be larger. 1649 */ 1650 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size); 1651 1652 /* Copy as many min_block or larger stored blocks directly to next_out as 1653 * possible. If flushing, copy the remaining available input to next_out as 1654 * stored blocks, if there is enough space. 1655 */ 1656 unsigned len, left, have, last = 0; 1657 unsigned used = s->strm->avail_in; 1658 do { 1659 /* Set len to the maximum size block that we can copy directly with the 1660 * available input data and output space. Set left to how much of that 1661 * would be copied from what's left in the window. 1662 */ 1663 len = MAX_STORED; /* maximum deflate stored block length */ 1664 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1665 if (s->strm->avail_out < have) /* need room for header */ 1666 break; 1667 /* maximum stored block length that will fit in avail_out: */ 1668 have = s->strm->avail_out - have; 1669 left = s->strstart - s->block_start; /* bytes left in window */ 1670 if (len > (ulg)left + s->strm->avail_in) 1671 len = left + s->strm->avail_in; /* limit len to the input */ 1672 if (len > have) 1673 len = have; /* limit len to the output */ 1674 1675 /* If the stored block would be less than min_block in length, or if 1676 * unable to copy all of the available input when flushing, then try 1677 * copying to the window and the pending buffer instead. Also don't 1678 * write an empty block when flushing -- deflate() does that. 1679 */ 1680 if (len < min_block && ((len == 0 && flush != Z_FINISH) || 1681 flush == Z_NO_FLUSH || 1682 len != left + s->strm->avail_in)) 1683 break; 1684 1685 /* Make a dummy stored block in pending to get the header bytes, 1686 * including any pending bits. This also updates the debugging counts. 1687 */ 1688 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0; 1689 _tr_stored_block(s, (char *)0, 0L, last); 1690 1691 /* Replace the lengths in the dummy stored block with len. */ 1692 s->pending_buf[s->pending - 4] = len; 1693 s->pending_buf[s->pending - 3] = len >> 8; 1694 s->pending_buf[s->pending - 2] = ~len; 1695 s->pending_buf[s->pending - 1] = ~len >> 8; 1696 1697 /* Write the stored block header bytes. */ 1698 flush_pending(s->strm); 1699 1700 #ifdef ZLIB_DEBUG 1701 /* Update debugging counts for the data about to be copied. */ 1702 s->compressed_len += len << 3; 1703 s->bits_sent += len << 3; 1704 #endif 1705 1706 /* Copy uncompressed bytes from the window to next_out. */ 1707 if (left) { 1708 if (left > len) 1709 left = len; 1710 zmemcpy(s->strm->next_out, s->window + s->block_start, left); 1711 s->strm->next_out += left; 1712 s->strm->avail_out -= left; 1713 s->strm->total_out += left; 1714 s->block_start += left; 1715 len -= left; 1716 } 1717 1718 /* Copy uncompressed bytes directly from next_in to next_out, updating 1719 * the check value. 1720 */ 1721 if (len) { 1722 read_buf(s->strm, s->strm->next_out, len); 1723 s->strm->next_out += len; 1724 s->strm->avail_out -= len; 1725 s->strm->total_out += len; 1726 } 1727 } while (last == 0); 1728 1729 /* Update the sliding window with the last s->w_size bytes of the copied 1730 * data, or append all of the copied data to the existing window if less 1731 * than s->w_size bytes were copied. Also update the number of bytes to 1732 * insert in the hash tables, in the event that deflateParams() switches to 1733 * a non-zero compression level. 1734 */ 1735 used -= s->strm->avail_in; /* number of input bytes directly copied */ 1736 if (used) { 1737 /* If any input was used, then no unused input remains in the window, 1738 * therefore s->block_start == s->strstart. 1739 */ 1740 if (used >= s->w_size) { /* supplant the previous history */ 1741 s->matches = 2; /* clear hash */ 1742 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size); 1743 s->strstart = s->w_size; 1744 } 1745 else { 1746 if (s->window_size - s->strstart <= used) { 1747 /* Slide the window down. */ 1748 s->strstart -= s->w_size; 1749 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1750 if (s->matches < 2) 1751 s->matches++; /* add a pending slide_hash() */ 1752 } 1753 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used); 1754 s->strstart += used; 1755 } 1756 s->block_start = s->strstart; 1757 s->insert += MIN(used, s->w_size - s->insert); 1758 } 1759 if (s->high_water < s->strstart) 1760 s->high_water = s->strstart; 1761 1762 /* If the last block was written to next_out, then done. */ 1763 if (last) 1764 return finish_done; 1765 1766 /* If flushing and all input has been consumed, then done. */ 1767 if (flush != Z_NO_FLUSH && flush != Z_FINISH && 1768 s->strm->avail_in == 0 && (long)s->strstart == s->block_start) 1769 return block_done; 1770 1771 /* Fill the window with any remaining input. */ 1772 have = s->window_size - s->strstart - 1; 1773 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) { 1774 /* Slide the window down. */ 1775 s->block_start -= s->w_size; 1776 s->strstart -= s->w_size; 1777 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1778 if (s->matches < 2) 1779 s->matches++; /* add a pending slide_hash() */ 1780 have += s->w_size; /* more space now */ 1781 } 1782 if (have > s->strm->avail_in) 1783 have = s->strm->avail_in; 1784 if (have) { 1785 read_buf(s->strm, s->window + s->strstart, have); 1786 s->strstart += have; 1787 } 1788 if (s->high_water < s->strstart) 1789 s->high_water = s->strstart; 1790 1791 /* There was not enough avail_out to write a complete worthy or flushed 1792 * stored block to next_out. Write a stored block to pending instead, if we 1793 * have enough input for a worthy block, or if flushing and there is enough 1794 * room for the remaining input as a stored block in the pending buffer. 1795 */ 1796 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1797 /* maximum stored block length that will fit in pending: */ 1798 have = MIN(s->pending_buf_size - have, MAX_STORED); 1799 min_block = MIN(have, s->w_size); 1800 left = s->strstart - s->block_start; 1801 if (left >= min_block || 1802 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH && 1803 s->strm->avail_in == 0 && left <= have)) { 1804 len = MIN(left, have); 1805 last = flush == Z_FINISH && s->strm->avail_in == 0 && 1806 len == left ? 1 : 0; 1807 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last); 1808 s->block_start += len; 1809 flush_pending(s->strm); 1810 } 1811 1812 /* We've done all we can with the available input and output. */ 1813 return last ? finish_started : need_more; 1814 } 1815 1816 /* =========================================================================== 1817 * Compress as much as possible from the input stream, return the current 1818 * block state. 1819 * This function does not perform lazy evaluation of matches and inserts 1820 * new strings in the dictionary only for unmatched strings or for short 1821 * matches. It is used only for the fast compression options. 1822 */ 1823 local block_state deflate_fast(s, flush) 1824 deflate_state *s; 1825 int flush; 1826 { 1827 IPos hash_head; /* head of the hash chain */ 1828 int bflush; /* set if current block must be flushed */ 1829 1830 for (;;) { 1831 /* Make sure that we always have enough lookahead, except 1832 * at the end of the input file. We need MAX_MATCH bytes 1833 * for the next match, plus MIN_MATCH bytes to insert the 1834 * string following the next match. 1835 */ 1836 if (s->lookahead < MIN_LOOKAHEAD) { 1837 fill_window(s); 1838 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1839 return need_more; 1840 } 1841 if (s->lookahead == 0) break; /* flush the current block */ 1842 } 1843 1844 /* Insert the string window[strstart .. strstart+2] in the 1845 * dictionary, and set hash_head to the head of the hash chain: 1846 */ 1847 hash_head = NIL; 1848 if (s->lookahead >= MIN_MATCH) { 1849 INSERT_STRING(s, s->strstart, hash_head); 1850 } 1851 1852 /* Find the longest match, discarding those <= prev_length. 1853 * At this point we have always match_length < MIN_MATCH 1854 */ 1855 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1856 /* To simplify the code, we prevent matches with the string 1857 * of window index 0 (in particular we have to avoid a match 1858 * of the string with itself at the start of the input file). 1859 */ 1860 s->match_length = longest_match (s, hash_head); 1861 /* longest_match() sets match_start */ 1862 } 1863 if (s->match_length >= MIN_MATCH) { 1864 check_match(s, s->strstart, s->match_start, s->match_length); 1865 1866 _tr_tally_dist(s, s->strstart - s->match_start, 1867 s->match_length - MIN_MATCH, bflush); 1868 1869 s->lookahead -= s->match_length; 1870 1871 /* Insert new strings in the hash table only if the match length 1872 * is not too large. This saves time but degrades compression. 1873 */ 1874 #ifndef FASTEST 1875 if (s->match_length <= s->max_insert_length && 1876 s->lookahead >= MIN_MATCH) { 1877 s->match_length--; /* string at strstart already in table */ 1878 do { 1879 s->strstart++; 1880 INSERT_STRING(s, s->strstart, hash_head); 1881 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1882 * always MIN_MATCH bytes ahead. 1883 */ 1884 } while (--s->match_length != 0); 1885 s->strstart++; 1886 } else 1887 #endif 1888 { 1889 s->strstart += s->match_length; 1890 s->match_length = 0; 1891 s->ins_h = s->window[s->strstart]; 1892 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); 1893 #if MIN_MATCH != 3 1894 Call UPDATE_HASH() MIN_MATCH-3 more times 1895 #endif 1896 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1897 * matter since it will be recomputed at next deflate call. 1898 */ 1899 } 1900 } else { 1901 /* No match, output a literal byte */ 1902 Tracevv((stderr,"%c", s->window[s->strstart])); 1903 _tr_tally_lit (s, s->window[s->strstart], bflush); 1904 s->lookahead--; 1905 s->strstart++; 1906 } 1907 if (bflush) FLUSH_BLOCK(s, 0); 1908 } 1909 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1910 if (flush == Z_FINISH) { 1911 FLUSH_BLOCK(s, 1); 1912 return finish_done; 1913 } 1914 if (s->last_lit) 1915 FLUSH_BLOCK(s, 0); 1916 return block_done; 1917 } 1918 1919 #ifndef FASTEST 1920 /* =========================================================================== 1921 * Same as above, but achieves better compression. We use a lazy 1922 * evaluation for matches: a match is finally adopted only if there is 1923 * no better match at the next window position. 1924 */ 1925 local block_state deflate_slow(s, flush) 1926 deflate_state *s; 1927 int flush; 1928 { 1929 IPos hash_head; /* head of hash chain */ 1930 int bflush; /* set if current block must be flushed */ 1931 1932 /* Process the input block. */ 1933 for (;;) { 1934 /* Make sure that we always have enough lookahead, except 1935 * at the end of the input file. We need MAX_MATCH bytes 1936 * for the next match, plus MIN_MATCH bytes to insert the 1937 * string following the next match. 1938 */ 1939 if (s->lookahead < MIN_LOOKAHEAD) { 1940 fill_window(s); 1941 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1942 return need_more; 1943 } 1944 if (s->lookahead == 0) break; /* flush the current block */ 1945 } 1946 1947 /* Insert the string window[strstart .. strstart+2] in the 1948 * dictionary, and set hash_head to the head of the hash chain: 1949 */ 1950 hash_head = NIL; 1951 if (s->lookahead >= MIN_MATCH) { 1952 INSERT_STRING(s, s->strstart, hash_head); 1953 } 1954 1955 /* Find the longest match, discarding those <= prev_length. 1956 */ 1957 s->prev_length = s->match_length, s->prev_match = s->match_start; 1958 s->match_length = MIN_MATCH-1; 1959 1960 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1961 s->strstart - hash_head <= MAX_DIST(s)) { 1962 /* To simplify the code, we prevent matches with the string 1963 * of window index 0 (in particular we have to avoid a match 1964 * of the string with itself at the start of the input file). 1965 */ 1966 s->match_length = longest_match (s, hash_head); 1967 /* longest_match() sets match_start */ 1968 1969 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1970 #if TOO_FAR <= 32767 1971 || (s->match_length == MIN_MATCH && 1972 s->strstart - s->match_start > TOO_FAR) 1973 #endif 1974 )) { 1975 1976 /* If prev_match is also MIN_MATCH, match_start is garbage 1977 * but we will ignore the current match anyway. 1978 */ 1979 s->match_length = MIN_MATCH-1; 1980 } 1981 } 1982 /* If there was a match at the previous step and the current 1983 * match is not better, output the previous match: 1984 */ 1985 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1986 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1987 /* Do not insert strings in hash table beyond this. */ 1988 1989 check_match(s, s->strstart-1, s->prev_match, s->prev_length); 1990 1991 _tr_tally_dist(s, s->strstart -1 - s->prev_match, 1992 s->prev_length - MIN_MATCH, bflush); 1993 1994 /* Insert in hash table all strings up to the end of the match. 1995 * strstart-1 and strstart are already inserted. If there is not 1996 * enough lookahead, the last two strings are not inserted in 1997 * the hash table. 1998 */ 1999 s->lookahead -= s->prev_length-1; 2000 s->prev_length -= 2; 2001 do { 2002 if (++s->strstart <= max_insert) { 2003 INSERT_STRING(s, s->strstart, hash_head); 2004 } 2005 } while (--s->prev_length != 0); 2006 s->match_available = 0; 2007 s->match_length = MIN_MATCH-1; 2008 s->strstart++; 2009 2010 if (bflush) FLUSH_BLOCK(s, 0); 2011 2012 } else if (s->match_available) { 2013 /* If there was no match at the previous position, output a 2014 * single literal. If there was a match but the current match 2015 * is longer, truncate the previous match to a single literal. 2016 */ 2017 Tracevv((stderr,"%c", s->window[s->strstart-1])); 2018 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 2019 if (bflush) { 2020 FLUSH_BLOCK_ONLY(s, 0); 2021 } 2022 s->strstart++; 2023 s->lookahead--; 2024 if (s->strm->avail_out == 0) return need_more; 2025 } else { 2026 /* There is no previous match to compare with, wait for 2027 * the next step to decide. 2028 */ 2029 s->match_available = 1; 2030 s->strstart++; 2031 s->lookahead--; 2032 } 2033 } 2034 Assert (flush != Z_NO_FLUSH, "no flush?"); 2035 if (s->match_available) { 2036 Tracevv((stderr,"%c", s->window[s->strstart-1])); 2037 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 2038 s->match_available = 0; 2039 } 2040 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 2041 if (flush == Z_FINISH) { 2042 FLUSH_BLOCK(s, 1); 2043 return finish_done; 2044 } 2045 if (s->last_lit) 2046 FLUSH_BLOCK(s, 0); 2047 return block_done; 2048 } 2049 #endif /* FASTEST */ 2050 2051 /* =========================================================================== 2052 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 2053 * one. Do not maintain a hash table. (It will be regenerated if this run of 2054 * deflate switches away from Z_RLE.) 2055 */ 2056 local block_state deflate_rle(s, flush) 2057 deflate_state *s; 2058 int flush; 2059 { 2060 int bflush; /* set if current block must be flushed */ 2061 uInt prev; /* byte at distance one to match */ 2062 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 2063 2064 for (;;) { 2065 /* Make sure that we always have enough lookahead, except 2066 * at the end of the input file. We need MAX_MATCH bytes 2067 * for the longest run, plus one for the unrolled loop. 2068 */ 2069 if (s->lookahead <= MAX_MATCH) { 2070 fill_window(s); 2071 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 2072 return need_more; 2073 } 2074 if (s->lookahead == 0) break; /* flush the current block */ 2075 } 2076 2077 /* See how many times the previous byte repeats */ 2078 s->match_length = 0; 2079 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 2080 scan = s->window + s->strstart - 1; 2081 prev = *scan; 2082 if (prev == *++scan && prev == *++scan && prev == *++scan) { 2083 strend = s->window + s->strstart + MAX_MATCH; 2084 do { 2085 } while (prev == *++scan && prev == *++scan && 2086 prev == *++scan && prev == *++scan && 2087 prev == *++scan && prev == *++scan && 2088 prev == *++scan && prev == *++scan && 2089 scan < strend); 2090 s->match_length = MAX_MATCH - (uInt)(strend - scan); 2091 if (s->match_length > s->lookahead) 2092 s->match_length = s->lookahead; 2093 } 2094 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan"); 2095 } 2096 2097 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 2098 if (s->match_length >= MIN_MATCH) { 2099 check_match(s, s->strstart, s->strstart - 1, s->match_length); 2100 2101 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 2102 2103 s->lookahead -= s->match_length; 2104 s->strstart += s->match_length; 2105 s->match_length = 0; 2106 } else { 2107 /* No match, output a literal byte */ 2108 Tracevv((stderr,"%c", s->window[s->strstart])); 2109 _tr_tally_lit (s, s->window[s->strstart], bflush); 2110 s->lookahead--; 2111 s->strstart++; 2112 } 2113 if (bflush) FLUSH_BLOCK(s, 0); 2114 } 2115 s->insert = 0; 2116 if (flush == Z_FINISH) { 2117 FLUSH_BLOCK(s, 1); 2118 return finish_done; 2119 } 2120 if (s->last_lit) 2121 FLUSH_BLOCK(s, 0); 2122 return block_done; 2123 } 2124 2125 /* =========================================================================== 2126 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 2127 * (It will be regenerated if this run of deflate switches away from Huffman.) 2128 */ 2129 local block_state deflate_huff(s, flush) 2130 deflate_state *s; 2131 int flush; 2132 { 2133 int bflush; /* set if current block must be flushed */ 2134 2135 for (;;) { 2136 /* Make sure that we have a literal to write. */ 2137 if (s->lookahead == 0) { 2138 fill_window(s); 2139 if (s->lookahead == 0) { 2140 if (flush == Z_NO_FLUSH) 2141 return need_more; 2142 break; /* flush the current block */ 2143 } 2144 } 2145 2146 /* Output a literal byte */ 2147 s->match_length = 0; 2148 Tracevv((stderr,"%c", s->window[s->strstart])); 2149 _tr_tally_lit (s, s->window[s->strstart], bflush); 2150 s->lookahead--; 2151 s->strstart++; 2152 if (bflush) FLUSH_BLOCK(s, 0); 2153 } 2154 s->insert = 0; 2155 if (flush == Z_FINISH) { 2156 FLUSH_BLOCK(s, 1); 2157 return finish_done; 2158 } 2159 if (s->last_lit) 2160 FLUSH_BLOCK(s, 0); 2161 return block_done; 2162 } 2163