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 #include "deflate.h" 51 52 const char deflate_copyright[] = 53 " deflate 1.2.11 Copyright 1995-2017 Jean-loup Gailly and Mark Adler "; 54 /* 55 If you use the zlib library in a product, an acknowledgment is welcome 56 in the documentation of your product. If for some reason you cannot 57 include such an acknowledgment, I would appreciate that you keep this 58 copyright string in the executable of your product. 59 */ 60 61 /* =========================================================================== 62 * Function prototypes. 63 */ 64 typedef enum { 65 need_more, /* block not completed, need more input or more output */ 66 block_done, /* block flush performed */ 67 finish_started, /* finish started, need only more output at next deflate */ 68 finish_done /* finish done, accept no more input or output */ 69 } block_state; 70 71 typedef block_state (*compress_func) OF((deflate_state *s, int flush)); 72 /* Compression function. Returns the block state after the call. */ 73 74 local int deflateStateCheck OF((z_streamp strm)); 75 local void slide_hash OF((deflate_state *s)); 76 local void fill_window OF((deflate_state *s)); 77 local block_state deflate_stored OF((deflate_state *s, int flush)); 78 local block_state deflate_fast OF((deflate_state *s, int flush)); 79 #ifndef FASTEST 80 local block_state deflate_slow OF((deflate_state *s, int flush)); 81 #endif 82 local block_state deflate_rle OF((deflate_state *s, int flush)); 83 local block_state deflate_huff OF((deflate_state *s, int flush)); 84 local void lm_init OF((deflate_state *s)); 85 local void putShortMSB OF((deflate_state *s, uInt b)); 86 local void flush_pending OF((z_streamp strm)); 87 local unsigned read_buf OF((z_streamp strm, Bytef *buf, unsigned size)); 88 #ifdef ASMV 89 # pragma message("Assembler code may have bugs -- use at your own risk") 90 void match_init OF((void)); /* asm code initialization */ 91 uInt longest_match OF((deflate_state *s, IPos cur_match)); 92 #else 93 local uInt longest_match OF((deflate_state *s, IPos cur_match)); 94 #endif 95 96 #ifdef ZLIB_DEBUG 97 local void check_match OF((deflate_state *s, IPos start, IPos match, 98 int length)); 99 #endif 100 101 /* =========================================================================== 102 * Local data 103 */ 104 105 #define NIL 0 106 /* Tail of hash chains */ 107 108 #ifndef TOO_FAR 109 # define TOO_FAR 4096 110 #endif 111 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ 112 113 /* Values for max_lazy_match, good_match and max_chain_length, depending on 114 * the desired pack level (0..9). The values given below have been tuned to 115 * exclude worst case performance for pathological files. Better values may be 116 * found for specific files. 117 */ 118 typedef struct config_s { 119 ush good_length; /* reduce lazy search above this match length */ 120 ush max_lazy; /* do not perform lazy search above this match length */ 121 ush nice_length; /* quit search above this match length */ 122 ush max_chain; 123 compress_func func; 124 } config; 125 126 #ifdef FASTEST 127 local const config configuration_table[2] = { 128 /* good lazy nice chain */ 129 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 130 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ 131 #else 132 local const config configuration_table[10] = { 133 /* good lazy nice chain */ 134 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 135 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ 136 /* 2 */ {4, 5, 16, 8, deflate_fast}, 137 /* 3 */ {4, 6, 32, 32, deflate_fast}, 138 139 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ 140 /* 5 */ {8, 16, 32, 32, deflate_slow}, 141 /* 6 */ {8, 16, 128, 128, deflate_slow}, 142 /* 7 */ {8, 32, 128, 256, deflate_slow}, 143 /* 8 */ {32, 128, 258, 1024, deflate_slow}, 144 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ 145 #endif 146 147 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 148 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different 149 * meaning. 150 */ 151 152 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */ 153 #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0)) 154 155 /* =========================================================================== 156 * Update a hash value with the given input byte 157 * IN assertion: all calls to UPDATE_HASH are made with consecutive input 158 * characters, so that a running hash key can be computed from the previous 159 * key instead of complete recalculation each time. 160 */ 161 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask) 162 163 164 /* =========================================================================== 165 * Insert string str in the dictionary and set match_head to the previous head 166 * of the hash chain (the most recent string with same hash key). Return 167 * the previous length of the hash chain. 168 * If this file is compiled with -DFASTEST, the compression level is forced 169 * to 1, and no hash chains are maintained. 170 * IN assertion: all calls to INSERT_STRING are made with consecutive input 171 * characters and the first MIN_MATCH bytes of str are valid (except for 172 * the last MIN_MATCH-1 bytes of the input file). 173 */ 174 #ifdef FASTEST 175 #define INSERT_STRING(s, str, match_head) \ 176 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 177 match_head = s->head[s->ins_h], \ 178 s->head[s->ins_h] = (Pos)(str)) 179 #else 180 #define INSERT_STRING(s, str, match_head) \ 181 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 182 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ 183 s->head[s->ins_h] = (Pos)(str)) 184 #endif 185 186 /* =========================================================================== 187 * Initialize the hash table (avoiding 64K overflow for 16 bit systems). 188 * prev[] will be initialized on the fly. 189 */ 190 #define CLEAR_HASH(s) \ 191 s->head[s->hash_size-1] = NIL; \ 192 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head)); 193 194 /* =========================================================================== 195 * Slide the hash table when sliding the window down (could be avoided with 32 196 * bit values at the expense of memory usage). We slide even when level == 0 to 197 * keep the hash table consistent if we switch back to level > 0 later. 198 */ 199 local void slide_hash(s) 200 deflate_state *s; 201 { 202 unsigned n, m; 203 Posf *p; 204 uInt wsize = s->w_size; 205 206 n = s->hash_size; 207 p = &s->head[n]; 208 do { 209 m = *--p; 210 *p = (Pos)(m >= wsize ? m - wsize : NIL); 211 } while (--n); 212 n = wsize; 213 #ifndef FASTEST 214 p = &s->prev[n]; 215 do { 216 m = *--p; 217 *p = (Pos)(m >= wsize ? m - wsize : NIL); 218 /* If n is not on any hash chain, prev[n] is garbage but 219 * its value will never be used. 220 */ 221 } while (--n); 222 #endif 223 } 224 225 /* ========================================================================= */ 226 int ZEXPORT deflateInit_(strm, level, version, stream_size) 227 z_streamp strm; 228 int level; 229 const char *version; 230 int stream_size; 231 { 232 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, 233 Z_DEFAULT_STRATEGY, version, stream_size); 234 /* To do: ignore strm->next_in if we use it as window */ 235 } 236 237 /* ========================================================================= */ 238 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy, 239 version, stream_size) 240 z_streamp strm; 241 int level; 242 int method; 243 int windowBits; 244 int memLevel; 245 int strategy; 246 const char *version; 247 int stream_size; 248 { 249 deflate_state *s; 250 int wrap = 1; 251 static const char my_version[] = ZLIB_VERSION; 252 253 ushf *overlay; 254 /* We overlay pending_buf and d_buf+l_buf. This works since the average 255 * output size for (length,distance) codes is <= 24 bits. 256 */ 257 258 if (version == Z_NULL || version[0] != my_version[0] || 259 stream_size != sizeof(z_stream)) { 260 return Z_VERSION_ERROR; 261 } 262 if (strm == Z_NULL) return Z_STREAM_ERROR; 263 264 strm->msg = Z_NULL; 265 if (strm->zalloc == (alloc_func)0) { 266 #ifdef Z_SOLO 267 return Z_STREAM_ERROR; 268 #else 269 strm->zalloc = zcalloc; 270 strm->opaque = (voidpf)0; 271 #endif 272 } 273 if (strm->zfree == (free_func)0) 274 #ifdef Z_SOLO 275 return Z_STREAM_ERROR; 276 #else 277 strm->zfree = zcfree; 278 #endif 279 280 #ifdef FASTEST 281 if (level != 0) level = 1; 282 #else 283 if (level == Z_DEFAULT_COMPRESSION) level = 6; 284 #endif 285 286 if (windowBits < 0) { /* suppress zlib wrapper */ 287 wrap = 0; 288 windowBits = -windowBits; 289 } 290 #ifdef GZIP 291 else if (windowBits > 15) { 292 wrap = 2; /* write gzip wrapper instead */ 293 windowBits -= 16; 294 } 295 #endif 296 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 297 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 298 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) { 299 return Z_STREAM_ERROR; 300 } 301 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 302 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 303 if (s == Z_NULL) return Z_MEM_ERROR; 304 strm->state = (struct internal_state FAR *)s; 305 s->strm = strm; 306 s->status = INIT_STATE; /* to pass state test in deflateReset() */ 307 308 s->wrap = wrap; 309 s->gzhead = Z_NULL; 310 s->w_bits = (uInt)windowBits; 311 s->w_size = 1 << s->w_bits; 312 s->w_mask = s->w_size - 1; 313 314 s->hash_bits = (uInt)memLevel + 7; 315 s->hash_size = 1 << s->hash_bits; 316 s->hash_mask = s->hash_size - 1; 317 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); 318 319 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 320 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 321 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 322 323 s->high_water = 0; /* nothing written to s->window yet */ 324 325 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 326 327 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); 328 s->pending_buf = (uchf *) overlay; 329 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); 330 331 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 332 s->pending_buf == Z_NULL) { 333 s->status = FINISH_STATE; 334 strm->msg = ERR_MSG(Z_MEM_ERROR); 335 deflateEnd (strm); 336 return Z_MEM_ERROR; 337 } 338 s->d_buf = overlay + s->lit_bufsize/sizeof(ush); 339 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; 340 341 s->level = level; 342 s->strategy = strategy; 343 s->method = (Byte)method; 344 345 return deflateReset(strm); 346 } 347 348 /* ========================================================================= 349 * Check for a valid deflate stream state. Return 0 if ok, 1 if not. 350 */ 351 local int deflateStateCheck (strm) 352 z_streamp strm; 353 { 354 deflate_state *s; 355 if (strm == Z_NULL || 356 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) 357 return 1; 358 s = strm->state; 359 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE && 360 #ifdef GZIP 361 s->status != GZIP_STATE && 362 #endif 363 s->status != EXTRA_STATE && 364 s->status != NAME_STATE && 365 s->status != COMMENT_STATE && 366 s->status != HCRC_STATE && 367 s->status != BUSY_STATE && 368 s->status != FINISH_STATE)) 369 return 1; 370 return 0; 371 } 372 373 /* ========================================================================= */ 374 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength) 375 z_streamp strm; 376 const Bytef *dictionary; 377 uInt dictLength; 378 { 379 deflate_state *s; 380 uInt str, n; 381 int wrap; 382 unsigned avail; 383 z_const unsigned char *next; 384 385 if (deflateStateCheck(strm) || dictionary == Z_NULL) 386 return Z_STREAM_ERROR; 387 s = strm->state; 388 wrap = s->wrap; 389 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) 390 return Z_STREAM_ERROR; 391 392 /* when using zlib wrappers, compute Adler-32 for provided dictionary */ 393 if (wrap == 1) 394 strm->adler = adler32(strm->adler, dictionary, dictLength); 395 s->wrap = 0; /* avoid computing Adler-32 in read_buf */ 396 397 /* if dictionary would fill window, just replace the history */ 398 if (dictLength >= s->w_size) { 399 if (wrap == 0) { /* already empty otherwise */ 400 CLEAR_HASH(s); 401 s->strstart = 0; 402 s->block_start = 0L; 403 s->insert = 0; 404 } 405 dictionary += dictLength - s->w_size; /* use the tail */ 406 dictLength = s->w_size; 407 } 408 409 /* insert dictionary into window and hash */ 410 avail = strm->avail_in; 411 next = strm->next_in; 412 strm->avail_in = dictLength; 413 strm->next_in = (z_const Bytef *)dictionary; 414 fill_window(s); 415 while (s->lookahead >= MIN_MATCH) { 416 str = s->strstart; 417 n = s->lookahead - (MIN_MATCH-1); 418 do { 419 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 420 #ifndef FASTEST 421 s->prev[str & s->w_mask] = s->head[s->ins_h]; 422 #endif 423 s->head[s->ins_h] = (Pos)str; 424 str++; 425 } while (--n); 426 s->strstart = str; 427 s->lookahead = MIN_MATCH-1; 428 fill_window(s); 429 } 430 s->strstart += s->lookahead; 431 s->block_start = (long)s->strstart; 432 s->insert = s->lookahead; 433 s->lookahead = 0; 434 s->match_length = s->prev_length = MIN_MATCH-1; 435 s->match_available = 0; 436 strm->next_in = next; 437 strm->avail_in = avail; 438 s->wrap = wrap; 439 return Z_OK; 440 } 441 442 /* ========================================================================= */ 443 int ZEXPORT deflateGetDictionary (strm, dictionary, dictLength) 444 z_streamp strm; 445 Bytef *dictionary; 446 uInt *dictLength; 447 { 448 deflate_state *s; 449 uInt len; 450 451 if (deflateStateCheck(strm)) 452 return Z_STREAM_ERROR; 453 s = strm->state; 454 len = s->strstart + s->lookahead; 455 if (len > s->w_size) 456 len = s->w_size; 457 if (dictionary != Z_NULL && len) 458 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len); 459 if (dictLength != Z_NULL) 460 *dictLength = len; 461 return Z_OK; 462 } 463 464 /* ========================================================================= */ 465 int ZEXPORT deflateResetKeep (strm) 466 z_streamp strm; 467 { 468 deflate_state *s; 469 470 if (deflateStateCheck(strm)) { 471 return Z_STREAM_ERROR; 472 } 473 474 strm->total_in = strm->total_out = 0; 475 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 476 strm->data_type = Z_UNKNOWN; 477 478 s = (deflate_state *)strm->state; 479 s->pending = 0; 480 s->pending_out = s->pending_buf; 481 482 if (s->wrap < 0) { 483 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 484 } 485 s->status = 486 #ifdef GZIP 487 s->wrap == 2 ? GZIP_STATE : 488 #endif 489 s->wrap ? INIT_STATE : BUSY_STATE; 490 strm->adler = 491 #ifdef GZIP 492 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 493 #endif 494 adler32(0L, Z_NULL, 0); 495 s->last_flush = Z_NO_FLUSH; 496 497 _tr_init(s); 498 499 return Z_OK; 500 } 501 502 /* ========================================================================= */ 503 int ZEXPORT deflateReset (strm) 504 z_streamp strm; 505 { 506 int ret; 507 508 ret = deflateResetKeep(strm); 509 if (ret == Z_OK) 510 lm_init(strm->state); 511 return ret; 512 } 513 514 /* ========================================================================= */ 515 int ZEXPORT deflateSetHeader (strm, head) 516 z_streamp strm; 517 gz_headerp head; 518 { 519 if (deflateStateCheck(strm) || strm->state->wrap != 2) 520 return Z_STREAM_ERROR; 521 strm->state->gzhead = head; 522 return Z_OK; 523 } 524 525 /* ========================================================================= */ 526 int ZEXPORT deflatePending (strm, pending, bits) 527 unsigned *pending; 528 int *bits; 529 z_streamp strm; 530 { 531 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 532 if (pending != Z_NULL) 533 *pending = strm->state->pending; 534 if (bits != Z_NULL) 535 *bits = strm->state->bi_valid; 536 return Z_OK; 537 } 538 539 /* ========================================================================= */ 540 int ZEXPORT deflatePrime (strm, bits, value) 541 z_streamp strm; 542 int bits; 543 int value; 544 { 545 deflate_state *s; 546 int put; 547 548 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 549 s = strm->state; 550 if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3)) 551 return Z_BUF_ERROR; 552 do { 553 put = Buf_size - s->bi_valid; 554 if (put > bits) 555 put = bits; 556 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); 557 s->bi_valid += put; 558 _tr_flush_bits(s); 559 value >>= put; 560 bits -= put; 561 } while (bits); 562 return Z_OK; 563 } 564 565 /* ========================================================================= */ 566 int ZEXPORT deflateParams(strm, level, strategy) 567 z_streamp strm; 568 int level; 569 int strategy; 570 { 571 deflate_state *s; 572 compress_func func; 573 574 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 575 s = strm->state; 576 577 #ifdef FASTEST 578 if (level != 0) level = 1; 579 #else 580 if (level == Z_DEFAULT_COMPRESSION) level = 6; 581 #endif 582 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 583 return Z_STREAM_ERROR; 584 } 585 func = configuration_table[s->level].func; 586 587 if ((strategy != s->strategy || func != configuration_table[level].func) && 588 s->high_water) { 589 /* Flush the last buffer: */ 590 int err = deflate(strm, Z_BLOCK); 591 if (err == Z_STREAM_ERROR) 592 return err; 593 if (strm->avail_out == 0) 594 return Z_BUF_ERROR; 595 } 596 if (s->level != level) { 597 if (s->level == 0 && s->matches != 0) { 598 if (s->matches == 1) 599 slide_hash(s); 600 else 601 CLEAR_HASH(s); 602 s->matches = 0; 603 } 604 s->level = level; 605 s->max_lazy_match = configuration_table[level].max_lazy; 606 s->good_match = configuration_table[level].good_length; 607 s->nice_match = configuration_table[level].nice_length; 608 s->max_chain_length = configuration_table[level].max_chain; 609 } 610 s->strategy = strategy; 611 return Z_OK; 612 } 613 614 /* ========================================================================= */ 615 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain) 616 z_streamp strm; 617 int good_length; 618 int max_lazy; 619 int nice_length; 620 int max_chain; 621 { 622 deflate_state *s; 623 624 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 625 s = strm->state; 626 s->good_match = (uInt)good_length; 627 s->max_lazy_match = (uInt)max_lazy; 628 s->nice_match = nice_length; 629 s->max_chain_length = (uInt)max_chain; 630 return Z_OK; 631 } 632 633 /* ========================================================================= 634 * For the default windowBits of 15 and memLevel of 8, this function returns 635 * a close to exact, as well as small, upper bound on the compressed size. 636 * They are coded as constants here for a reason--if the #define's are 637 * changed, then this function needs to be changed as well. The return 638 * value for 15 and 8 only works for those exact settings. 639 * 640 * For any setting other than those defaults for windowBits and memLevel, 641 * the value returned is a conservative worst case for the maximum expansion 642 * resulting from using fixed blocks instead of stored blocks, which deflate 643 * can emit on compressed data for some combinations of the parameters. 644 * 645 * This function could be more sophisticated to provide closer upper bounds for 646 * every combination of windowBits and memLevel. But even the conservative 647 * upper bound of about 14% expansion does not seem onerous for output buffer 648 * allocation. 649 */ 650 uLong ZEXPORT deflateBound(strm, sourceLen) 651 z_streamp strm; 652 uLong sourceLen; 653 { 654 deflate_state *s; 655 uLong complen, wraplen; 656 657 /* conservative upper bound for compressed data */ 658 complen = sourceLen + 659 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5; 660 661 /* if can't get parameters, return conservative bound plus zlib wrapper */ 662 if (deflateStateCheck(strm)) 663 return complen + 6; 664 665 /* compute wrapper length */ 666 s = strm->state; 667 switch (s->wrap) { 668 case 0: /* raw deflate */ 669 wraplen = 0; 670 break; 671 case 1: /* zlib wrapper */ 672 wraplen = 6 + (s->strstart ? 4 : 0); 673 break; 674 #ifdef GZIP 675 case 2: /* gzip wrapper */ 676 wraplen = 18; 677 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 678 Bytef *str; 679 if (s->gzhead->extra != Z_NULL) 680 wraplen += 2 + s->gzhead->extra_len; 681 str = s->gzhead->name; 682 if (str != Z_NULL) 683 do { 684 wraplen++; 685 } while (*str++); 686 str = s->gzhead->comment; 687 if (str != Z_NULL) 688 do { 689 wraplen++; 690 } while (*str++); 691 if (s->gzhead->hcrc) 692 wraplen += 2; 693 } 694 break; 695 #endif 696 default: /* for compiler happiness */ 697 wraplen = 6; 698 } 699 700 /* if not default parameters, return conservative bound */ 701 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 702 return complen + wraplen; 703 704 /* default settings: return tight bound for that case */ 705 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 706 (sourceLen >> 25) + 13 - 6 + wraplen; 707 } 708 709 /* ========================================================================= 710 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 711 * IN assertion: the stream state is correct and there is enough room in 712 * pending_buf. 713 */ 714 local void putShortMSB (s, b) 715 deflate_state *s; 716 uInt b; 717 { 718 put_byte(s, (Byte)(b >> 8)); 719 put_byte(s, (Byte)(b & 0xff)); 720 } 721 722 /* ========================================================================= 723 * Flush as much pending output as possible. All deflate() output, except for 724 * some deflate_stored() output, goes through this function so some 725 * applications may wish to modify it to avoid allocating a large 726 * strm->next_out buffer and copying into it. (See also read_buf()). 727 */ 728 local void flush_pending(strm) 729 z_streamp strm; 730 { 731 unsigned len; 732 deflate_state *s = strm->state; 733 734 _tr_flush_bits(s); 735 len = s->pending; 736 if (len > strm->avail_out) len = strm->avail_out; 737 if (len == 0) return; 738 739 zmemcpy(strm->next_out, s->pending_out, len); 740 strm->next_out += len; 741 s->pending_out += len; 742 strm->total_out += len; 743 strm->avail_out -= len; 744 s->pending -= len; 745 if (s->pending == 0) { 746 s->pending_out = s->pending_buf; 747 } 748 } 749 750 /* =========================================================================== 751 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1]. 752 */ 753 #define HCRC_UPDATE(beg) \ 754 do { \ 755 if (s->gzhead->hcrc && s->pending > (beg)) \ 756 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \ 757 s->pending - (beg)); \ 758 } while (0) 759 760 /* ========================================================================= */ 761 int ZEXPORT deflate (strm, flush) 762 z_streamp strm; 763 int flush; 764 { 765 int old_flush; /* value of flush param for previous deflate call */ 766 deflate_state *s; 767 768 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { 769 return Z_STREAM_ERROR; 770 } 771 s = strm->state; 772 773 if (strm->next_out == Z_NULL || 774 (strm->avail_in != 0 && strm->next_in == Z_NULL) || 775 (s->status == FINISH_STATE && flush != Z_FINISH)) { 776 ERR_RETURN(strm, Z_STREAM_ERROR); 777 } 778 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 779 780 old_flush = s->last_flush; 781 s->last_flush = flush; 782 783 /* Flush as much pending output as possible */ 784 if (s->pending != 0) { 785 flush_pending(strm); 786 if (strm->avail_out == 0) { 787 /* Since avail_out is 0, deflate will be called again with 788 * more output space, but possibly with both pending and 789 * avail_in equal to zero. There won't be anything to do, 790 * but this is not an error situation so make sure we 791 * return OK instead of BUF_ERROR at next call of deflate: 792 */ 793 s->last_flush = -1; 794 return Z_OK; 795 } 796 797 /* Make sure there is something to do and avoid duplicate consecutive 798 * flushes. For repeated and useless calls with Z_FINISH, we keep 799 * returning Z_STREAM_END instead of Z_BUF_ERROR. 800 */ 801 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 802 flush != Z_FINISH) { 803 ERR_RETURN(strm, Z_BUF_ERROR); 804 } 805 806 /* User must not provide more input after the first FINISH: */ 807 if (s->status == FINISH_STATE && strm->avail_in != 0) { 808 ERR_RETURN(strm, Z_BUF_ERROR); 809 } 810 811 /* Write the header */ 812 if (s->status == INIT_STATE) { 813 /* zlib header */ 814 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; 815 uInt level_flags; 816 817 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 818 level_flags = 0; 819 else if (s->level < 6) 820 level_flags = 1; 821 else if (s->level == 6) 822 level_flags = 2; 823 else 824 level_flags = 3; 825 header |= (level_flags << 6); 826 if (s->strstart != 0) header |= PRESET_DICT; 827 header += 31 - (header % 31); 828 829 putShortMSB(s, header); 830 831 /* Save the adler32 of the preset dictionary: */ 832 if (s->strstart != 0) { 833 putShortMSB(s, (uInt)(strm->adler >> 16)); 834 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 835 } 836 strm->adler = adler32(0L, Z_NULL, 0); 837 s->status = BUSY_STATE; 838 839 /* Compression must start with an empty pending buffer */ 840 flush_pending(strm); 841 if (s->pending != 0) { 842 s->last_flush = -1; 843 return Z_OK; 844 } 845 } 846 #ifdef GZIP 847 if (s->status == GZIP_STATE) { 848 /* gzip header */ 849 strm->adler = crc32(0L, Z_NULL, 0); 850 put_byte(s, 31); 851 put_byte(s, 139); 852 put_byte(s, 8); 853 if (s->gzhead == Z_NULL) { 854 put_byte(s, 0); 855 put_byte(s, 0); 856 put_byte(s, 0); 857 put_byte(s, 0); 858 put_byte(s, 0); 859 put_byte(s, s->level == 9 ? 2 : 860 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 861 4 : 0)); 862 put_byte(s, OS_CODE); 863 s->status = BUSY_STATE; 864 865 /* Compression must start with an empty pending buffer */ 866 flush_pending(strm); 867 if (s->pending != 0) { 868 s->last_flush = -1; 869 return Z_OK; 870 } 871 } 872 else { 873 put_byte(s, (s->gzhead->text ? 1 : 0) + 874 (s->gzhead->hcrc ? 2 : 0) + 875 (s->gzhead->extra == Z_NULL ? 0 : 4) + 876 (s->gzhead->name == Z_NULL ? 0 : 8) + 877 (s->gzhead->comment == Z_NULL ? 0 : 16) 878 ); 879 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 880 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 881 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 882 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 883 put_byte(s, s->level == 9 ? 2 : 884 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 885 4 : 0)); 886 put_byte(s, s->gzhead->os & 0xff); 887 if (s->gzhead->extra != Z_NULL) { 888 put_byte(s, s->gzhead->extra_len & 0xff); 889 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 890 } 891 if (s->gzhead->hcrc) 892 strm->adler = crc32(strm->adler, s->pending_buf, 893 s->pending); 894 s->gzindex = 0; 895 s->status = EXTRA_STATE; 896 } 897 } 898 if (s->status == EXTRA_STATE) { 899 if (s->gzhead->extra != Z_NULL) { 900 ulg beg = s->pending; /* start of bytes to update crc */ 901 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex; 902 while (s->pending + left > s->pending_buf_size) { 903 uInt copy = s->pending_buf_size - s->pending; 904 zmemcpy(s->pending_buf + s->pending, 905 s->gzhead->extra + s->gzindex, copy); 906 s->pending = s->pending_buf_size; 907 HCRC_UPDATE(beg); 908 s->gzindex += copy; 909 flush_pending(strm); 910 if (s->pending != 0) { 911 s->last_flush = -1; 912 return Z_OK; 913 } 914 beg = 0; 915 left -= copy; 916 } 917 zmemcpy(s->pending_buf + s->pending, 918 s->gzhead->extra + s->gzindex, left); 919 s->pending += left; 920 HCRC_UPDATE(beg); 921 s->gzindex = 0; 922 } 923 s->status = NAME_STATE; 924 } 925 if (s->status == NAME_STATE) { 926 if (s->gzhead->name != Z_NULL) { 927 ulg beg = s->pending; /* start of bytes to update crc */ 928 int val; 929 do { 930 if (s->pending == s->pending_buf_size) { 931 HCRC_UPDATE(beg); 932 flush_pending(strm); 933 if (s->pending != 0) { 934 s->last_flush = -1; 935 return Z_OK; 936 } 937 beg = 0; 938 } 939 val = s->gzhead->name[s->gzindex++]; 940 put_byte(s, val); 941 } while (val != 0); 942 HCRC_UPDATE(beg); 943 s->gzindex = 0; 944 } 945 s->status = COMMENT_STATE; 946 } 947 if (s->status == COMMENT_STATE) { 948 if (s->gzhead->comment != Z_NULL) { 949 ulg beg = s->pending; /* start of bytes to update crc */ 950 int val; 951 do { 952 if (s->pending == s->pending_buf_size) { 953 HCRC_UPDATE(beg); 954 flush_pending(strm); 955 if (s->pending != 0) { 956 s->last_flush = -1; 957 return Z_OK; 958 } 959 beg = 0; 960 } 961 val = s->gzhead->comment[s->gzindex++]; 962 put_byte(s, val); 963 } while (val != 0); 964 HCRC_UPDATE(beg); 965 } 966 s->status = HCRC_STATE; 967 } 968 if (s->status == HCRC_STATE) { 969 if (s->gzhead->hcrc) { 970 if (s->pending + 2 > s->pending_buf_size) { 971 flush_pending(strm); 972 if (s->pending != 0) { 973 s->last_flush = -1; 974 return Z_OK; 975 } 976 } 977 put_byte(s, (Byte)(strm->adler & 0xff)); 978 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 979 strm->adler = crc32(0L, Z_NULL, 0); 980 } 981 s->status = BUSY_STATE; 982 983 /* Compression must start with an empty pending buffer */ 984 flush_pending(strm); 985 if (s->pending != 0) { 986 s->last_flush = -1; 987 return Z_OK; 988 } 989 } 990 #endif 991 992 /* Start a new block or continue the current one. 993 */ 994 if (strm->avail_in != 0 || s->lookahead != 0 || 995 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 996 block_state bstate; 997 998 bstate = s->level == 0 ? deflate_stored(s, flush) : 999 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 1000 s->strategy == Z_RLE ? deflate_rle(s, flush) : 1001 (*(configuration_table[s->level].func))(s, flush); 1002 1003 if (bstate == finish_started || bstate == finish_done) { 1004 s->status = FINISH_STATE; 1005 } 1006 if (bstate == need_more || bstate == finish_started) { 1007 if (strm->avail_out == 0) { 1008 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 1009 } 1010 return Z_OK; 1011 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 1012 * of deflate should use the same flush parameter to make sure 1013 * that the flush is complete. So we don't have to output an 1014 * empty block here, this will be done at next call. This also 1015 * ensures that for a very small output buffer, we emit at most 1016 * one empty block. 1017 */ 1018 } 1019 if (bstate == block_done) { 1020 if (flush == Z_PARTIAL_FLUSH) { 1021 _tr_align(s); 1022 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 1023 _tr_stored_block(s, (char*)0, 0L, 0); 1024 /* For a full flush, this empty block will be recognized 1025 * as a special marker by inflate_sync(). 1026 */ 1027 if (flush == Z_FULL_FLUSH) { 1028 CLEAR_HASH(s); /* forget history */ 1029 if (s->lookahead == 0) { 1030 s->strstart = 0; 1031 s->block_start = 0L; 1032 s->insert = 0; 1033 } 1034 } 1035 } 1036 flush_pending(strm); 1037 if (strm->avail_out == 0) { 1038 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 1039 return Z_OK; 1040 } 1041 } 1042 } 1043 1044 if (flush != Z_FINISH) return Z_OK; 1045 if (s->wrap <= 0) return Z_STREAM_END; 1046 1047 /* Write the trailer */ 1048 #ifdef GZIP 1049 if (s->wrap == 2) { 1050 put_byte(s, (Byte)(strm->adler & 0xff)); 1051 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1052 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 1053 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 1054 put_byte(s, (Byte)(strm->total_in & 0xff)); 1055 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 1056 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 1057 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 1058 } 1059 else 1060 #endif 1061 { 1062 putShortMSB(s, (uInt)(strm->adler >> 16)); 1063 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1064 } 1065 flush_pending(strm); 1066 /* If avail_out is zero, the application will call deflate again 1067 * to flush the rest. 1068 */ 1069 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 1070 return s->pending != 0 ? Z_OK : Z_STREAM_END; 1071 } 1072 1073 /* ========================================================================= */ 1074 int ZEXPORT deflateEnd (strm) 1075 z_streamp strm; 1076 { 1077 int status; 1078 1079 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 1080 1081 status = strm->state->status; 1082 1083 /* Deallocate in reverse order of allocations: */ 1084 TRY_FREE(strm, strm->state->pending_buf); 1085 TRY_FREE(strm, strm->state->head); 1086 TRY_FREE(strm, strm->state->prev); 1087 TRY_FREE(strm, strm->state->window); 1088 1089 ZFREE(strm, strm->state); 1090 strm->state = Z_NULL; 1091 1092 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1093 } 1094 1095 /* ========================================================================= 1096 * Copy the source state to the destination state. 1097 * To simplify the source, this is not supported for 16-bit MSDOS (which 1098 * doesn't have enough memory anyway to duplicate compression states). 1099 */ 1100 int ZEXPORT deflateCopy (dest, source) 1101 z_streamp dest; 1102 z_streamp source; 1103 { 1104 #ifdef MAXSEG_64K 1105 return Z_STREAM_ERROR; 1106 #else 1107 deflate_state *ds; 1108 deflate_state *ss; 1109 ushf *overlay; 1110 1111 1112 if (deflateStateCheck(source) || dest == Z_NULL) { 1113 return Z_STREAM_ERROR; 1114 } 1115 1116 ss = source->state; 1117 1118 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream)); 1119 1120 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1121 if (ds == Z_NULL) return Z_MEM_ERROR; 1122 dest->state = (struct internal_state FAR *) ds; 1123 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state)); 1124 ds->strm = dest; 1125 1126 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1127 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1128 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1129 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); 1130 ds->pending_buf = (uchf *) overlay; 1131 1132 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1133 ds->pending_buf == Z_NULL) { 1134 deflateEnd (dest); 1135 return Z_MEM_ERROR; 1136 } 1137 /* following zmemcpy do not work for 16-bit MSDOS */ 1138 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1139 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos)); 1140 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos)); 1141 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); 1142 1143 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1144 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); 1145 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; 1146 1147 ds->l_desc.dyn_tree = ds->dyn_ltree; 1148 ds->d_desc.dyn_tree = ds->dyn_dtree; 1149 ds->bl_desc.dyn_tree = ds->bl_tree; 1150 1151 return Z_OK; 1152 #endif /* MAXSEG_64K */ 1153 } 1154 1155 /* =========================================================================== 1156 * Read a new buffer from the current input stream, update the adler32 1157 * and total number of bytes read. All deflate() input goes through 1158 * this function so some applications may wish to modify it to avoid 1159 * allocating a large strm->next_in buffer and copying from it. 1160 * (See also flush_pending()). 1161 */ 1162 local unsigned read_buf(strm, buf, size) 1163 z_streamp strm; 1164 Bytef *buf; 1165 unsigned size; 1166 { 1167 unsigned len = strm->avail_in; 1168 1169 if (len > size) len = size; 1170 if (len == 0) return 0; 1171 1172 strm->avail_in -= len; 1173 1174 zmemcpy(buf, strm->next_in, len); 1175 if (strm->state->wrap == 1) { 1176 strm->adler = adler32(strm->adler, buf, len); 1177 } 1178 #ifdef GZIP 1179 else if (strm->state->wrap == 2) { 1180 strm->adler = crc32(strm->adler, buf, len); 1181 } 1182 #endif 1183 strm->next_in += len; 1184 strm->total_in += len; 1185 1186 return len; 1187 } 1188 1189 /* =========================================================================== 1190 * Initialize the "longest match" routines for a new zlib stream 1191 */ 1192 local void lm_init (s) 1193 deflate_state *s; 1194 { 1195 s->window_size = (ulg)2L*s->w_size; 1196 1197 CLEAR_HASH(s); 1198 1199 /* Set the default configuration parameters: 1200 */ 1201 s->max_lazy_match = configuration_table[s->level].max_lazy; 1202 s->good_match = configuration_table[s->level].good_length; 1203 s->nice_match = configuration_table[s->level].nice_length; 1204 s->max_chain_length = configuration_table[s->level].max_chain; 1205 1206 s->strstart = 0; 1207 s->block_start = 0L; 1208 s->lookahead = 0; 1209 s->insert = 0; 1210 s->match_length = s->prev_length = MIN_MATCH-1; 1211 s->match_available = 0; 1212 s->ins_h = 0; 1213 #ifndef FASTEST 1214 #ifdef ASMV 1215 match_init(); /* initialize the asm code */ 1216 #endif 1217 #endif 1218 } 1219 1220 #ifndef FASTEST 1221 /* =========================================================================== 1222 * Set match_start to the longest match starting at the given string and 1223 * return its length. Matches shorter or equal to prev_length are discarded, 1224 * in which case the result is equal to prev_length and match_start is 1225 * garbage. 1226 * IN assertions: cur_match is the head of the hash chain for the current 1227 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1228 * OUT assertion: the match length is not greater than s->lookahead. 1229 */ 1230 #ifndef ASMV 1231 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or 1232 * match.S. The code will be functionally equivalent. 1233 */ 1234 local uInt longest_match(s, cur_match) 1235 deflate_state *s; 1236 IPos cur_match; /* current match */ 1237 { 1238 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1239 register Bytef *scan = s->window + s->strstart; /* current string */ 1240 register Bytef *match; /* matched string */ 1241 register int len; /* length of current match */ 1242 int best_len = (int)s->prev_length; /* best match length so far */ 1243 int nice_match = s->nice_match; /* stop if match long enough */ 1244 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1245 s->strstart - (IPos)MAX_DIST(s) : NIL; 1246 /* Stop when cur_match becomes <= limit. To simplify the code, 1247 * we prevent matches with the string of window index 0. 1248 */ 1249 Posf *prev = s->prev; 1250 uInt wmask = s->w_mask; 1251 1252 #ifdef UNALIGNED_OK 1253 /* Compare two bytes at a time. Note: this is not always beneficial. 1254 * Try with and without -DUNALIGNED_OK to check. 1255 */ 1256 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1257 register ush scan_start = *(ushf*)scan; 1258 register ush scan_end = *(ushf*)(scan+best_len-1); 1259 #else 1260 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1261 register Byte scan_end1 = scan[best_len-1]; 1262 register Byte scan_end = scan[best_len]; 1263 #endif 1264 1265 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1266 * It is easy to get rid of this optimization if necessary. 1267 */ 1268 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1269 1270 /* Do not waste too much time if we already have a good match: */ 1271 if (s->prev_length >= s->good_match) { 1272 chain_length >>= 2; 1273 } 1274 /* Do not look for matches beyond the end of the input. This is necessary 1275 * to make deflate deterministic. 1276 */ 1277 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead; 1278 1279 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1280 1281 do { 1282 Assert(cur_match < s->strstart, "no future"); 1283 match = s->window + cur_match; 1284 1285 /* Skip to next match if the match length cannot increase 1286 * or if the match length is less than 2. Note that the checks below 1287 * for insufficient lookahead only occur occasionally for performance 1288 * reasons. Therefore uninitialized memory will be accessed, and 1289 * conditional jumps will be made that depend on those values. 1290 * However the length of the match is limited to the lookahead, so 1291 * the output of deflate is not affected by the uninitialized values. 1292 */ 1293 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1294 /* This code assumes sizeof(unsigned short) == 2. Do not use 1295 * UNALIGNED_OK if your compiler uses a different size. 1296 */ 1297 if (*(ushf*)(match+best_len-1) != scan_end || 1298 *(ushf*)match != scan_start) continue; 1299 1300 /* It is not necessary to compare scan[2] and match[2] since they are 1301 * always equal when the other bytes match, given that the hash keys 1302 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1303 * strstart+3, +5, ... up to strstart+257. We check for insufficient 1304 * lookahead only every 4th comparison; the 128th check will be made 1305 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is 1306 * necessary to put more guard bytes at the end of the window, or 1307 * to check more often for insufficient lookahead. 1308 */ 1309 Assert(scan[2] == match[2], "scan[2]?"); 1310 scan++, match++; 1311 do { 1312 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1313 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1314 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1315 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1316 scan < strend); 1317 /* The funny "do {}" generates better code on most compilers */ 1318 1319 /* Here, scan <= window+strstart+257 */ 1320 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1321 if (*scan == *match) scan++; 1322 1323 len = (MAX_MATCH - 1) - (int)(strend-scan); 1324 scan = strend - (MAX_MATCH-1); 1325 1326 #else /* UNALIGNED_OK */ 1327 1328 if (match[best_len] != scan_end || 1329 match[best_len-1] != scan_end1 || 1330 *match != *scan || 1331 *++match != scan[1]) continue; 1332 1333 /* The check at best_len-1 can be removed because it will be made 1334 * again later. (This heuristic is not always a win.) 1335 * It is not necessary to compare scan[2] and match[2] since they 1336 * are always equal when the other bytes match, given that 1337 * the hash keys are equal and that HASH_BITS >= 8. 1338 */ 1339 scan += 2, match++; 1340 Assert(*scan == *match, "match[2]?"); 1341 1342 /* We check for insufficient lookahead only every 8th comparison; 1343 * the 256th check will be made at strstart+258. 1344 */ 1345 do { 1346 } while (*++scan == *++match && *++scan == *++match && 1347 *++scan == *++match && *++scan == *++match && 1348 *++scan == *++match && *++scan == *++match && 1349 *++scan == *++match && *++scan == *++match && 1350 scan < strend); 1351 1352 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1353 1354 len = MAX_MATCH - (int)(strend - scan); 1355 scan = strend - MAX_MATCH; 1356 1357 #endif /* UNALIGNED_OK */ 1358 1359 if (len > best_len) { 1360 s->match_start = cur_match; 1361 best_len = len; 1362 if (len >= nice_match) break; 1363 #ifdef UNALIGNED_OK 1364 scan_end = *(ushf*)(scan+best_len-1); 1365 #else 1366 scan_end1 = scan[best_len-1]; 1367 scan_end = scan[best_len]; 1368 #endif 1369 } 1370 } while ((cur_match = prev[cur_match & wmask]) > limit 1371 && --chain_length != 0); 1372 1373 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1374 return s->lookahead; 1375 } 1376 #endif /* ASMV */ 1377 1378 #else /* FASTEST */ 1379 1380 /* --------------------------------------------------------------------------- 1381 * Optimized version for FASTEST only 1382 */ 1383 local uInt longest_match(s, cur_match) 1384 deflate_state *s; 1385 IPos cur_match; /* current match */ 1386 { 1387 register Bytef *scan = s->window + s->strstart; /* current string */ 1388 register Bytef *match; /* matched string */ 1389 register int len; /* length of current match */ 1390 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1391 1392 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1393 * It is easy to get rid of this optimization if necessary. 1394 */ 1395 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1396 1397 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1398 1399 Assert(cur_match < s->strstart, "no future"); 1400 1401 match = s->window + cur_match; 1402 1403 /* Return failure if the match length is less than 2: 1404 */ 1405 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1406 1407 /* The check at best_len-1 can be removed because it will be made 1408 * again later. (This heuristic is not always a win.) 1409 * It is not necessary to compare scan[2] and match[2] since they 1410 * are always equal when the other bytes match, given that 1411 * the hash keys are equal and that HASH_BITS >= 8. 1412 */ 1413 scan += 2, match += 2; 1414 Assert(*scan == *match, "match[2]?"); 1415 1416 /* We check for insufficient lookahead only every 8th comparison; 1417 * the 256th check will be made at strstart+258. 1418 */ 1419 do { 1420 } while (*++scan == *++match && *++scan == *++match && 1421 *++scan == *++match && *++scan == *++match && 1422 *++scan == *++match && *++scan == *++match && 1423 *++scan == *++match && *++scan == *++match && 1424 scan < strend); 1425 1426 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1427 1428 len = MAX_MATCH - (int)(strend - scan); 1429 1430 if (len < MIN_MATCH) return MIN_MATCH - 1; 1431 1432 s->match_start = cur_match; 1433 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1434 } 1435 1436 #endif /* FASTEST */ 1437 1438 #ifdef ZLIB_DEBUG 1439 1440 #define EQUAL 0 1441 /* result of memcmp for equal strings */ 1442 1443 /* =========================================================================== 1444 * Check that the match at match_start is indeed a match. 1445 */ 1446 local void check_match(s, start, match, length) 1447 deflate_state *s; 1448 IPos start, match; 1449 int length; 1450 { 1451 /* check that the match is indeed a match */ 1452 if (zmemcmp(s->window + match, 1453 s->window + start, length) != EQUAL) { 1454 fprintf(stderr, " start %u, match %u, length %d\n", 1455 start, match, length); 1456 do { 1457 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); 1458 } while (--length != 0); 1459 z_error("invalid match"); 1460 } 1461 if (z_verbose > 1) { 1462 fprintf(stderr,"\\[%d,%d]", start-match, length); 1463 do { putc(s->window[start++], stderr); } while (--length != 0); 1464 } 1465 } 1466 #else 1467 # define check_match(s, start, match, length) 1468 #endif /* ZLIB_DEBUG */ 1469 1470 /* =========================================================================== 1471 * Fill the window when the lookahead becomes insufficient. 1472 * Updates strstart and lookahead. 1473 * 1474 * IN assertion: lookahead < MIN_LOOKAHEAD 1475 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 1476 * At least one byte has been read, or avail_in == 0; reads are 1477 * performed for at least two bytes (required for the zip translate_eol 1478 * option -- not supported here). 1479 */ 1480 local void fill_window(s) 1481 deflate_state *s; 1482 { 1483 unsigned n; 1484 unsigned more; /* Amount of free space at the end of the window. */ 1485 uInt wsize = s->w_size; 1486 1487 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); 1488 1489 do { 1490 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 1491 1492 /* Deal with !@#$% 64K limit: */ 1493 if (sizeof(int) <= 2) { 1494 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 1495 more = wsize; 1496 1497 } else if (more == (unsigned)(-1)) { 1498 /* Very unlikely, but possible on 16 bit machine if 1499 * strstart == 0 && lookahead == 1 (input done a byte at time) 1500 */ 1501 more--; 1502 } 1503 } 1504 1505 /* If the window is almost full and there is insufficient lookahead, 1506 * move the upper half to the lower one to make room in the upper half. 1507 */ 1508 if (s->strstart >= wsize+MAX_DIST(s)) { 1509 1510 zmemcpy(s->window, s->window+wsize, (unsigned)wsize - more); 1511 s->match_start -= wsize; 1512 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 1513 s->block_start -= (long) wsize; 1514 slide_hash(s); 1515 more += wsize; 1516 } 1517 if (s->strm->avail_in == 0) break; 1518 1519 /* If there was no sliding: 1520 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 1521 * more == window_size - lookahead - strstart 1522 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 1523 * => more >= window_size - 2*WSIZE + 2 1524 * In the BIG_MEM or MMAP case (not yet supported), 1525 * window_size == input_size + MIN_LOOKAHEAD && 1526 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 1527 * Otherwise, window_size == 2*WSIZE so more >= 2. 1528 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 1529 */ 1530 Assert(more >= 2, "more < 2"); 1531 1532 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 1533 s->lookahead += n; 1534 1535 /* Initialize the hash value now that we have some input: */ 1536 if (s->lookahead + s->insert >= MIN_MATCH) { 1537 uInt str = s->strstart - s->insert; 1538 s->ins_h = s->window[str]; 1539 UPDATE_HASH(s, s->ins_h, s->window[str + 1]); 1540 #if MIN_MATCH != 3 1541 Call UPDATE_HASH() MIN_MATCH-3 more times 1542 #endif 1543 while (s->insert) { 1544 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 1545 #ifndef FASTEST 1546 s->prev[str & s->w_mask] = s->head[s->ins_h]; 1547 #endif 1548 s->head[s->ins_h] = (Pos)str; 1549 str++; 1550 s->insert--; 1551 if (s->lookahead + s->insert < MIN_MATCH) 1552 break; 1553 } 1554 } 1555 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 1556 * but this is not important since only literal bytes will be emitted. 1557 */ 1558 1559 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 1560 1561 /* If the WIN_INIT bytes after the end of the current data have never been 1562 * written, then zero those bytes in order to avoid memory check reports of 1563 * the use of uninitialized (or uninitialised as Julian writes) bytes by 1564 * the longest match routines. Update the high water mark for the next 1565 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 1566 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 1567 */ 1568 if (s->high_water < s->window_size) { 1569 ulg curr = s->strstart + (ulg)(s->lookahead); 1570 ulg init; 1571 1572 if (s->high_water < curr) { 1573 /* Previous high water mark below current data -- zero WIN_INIT 1574 * bytes or up to end of window, whichever is less. 1575 */ 1576 init = s->window_size - curr; 1577 if (init > WIN_INIT) 1578 init = WIN_INIT; 1579 zmemzero(s->window + curr, (unsigned)init); 1580 s->high_water = curr + init; 1581 } 1582 else if (s->high_water < (ulg)curr + WIN_INIT) { 1583 /* High water mark at or above current data, but below current data 1584 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 1585 * to end of window, whichever is less. 1586 */ 1587 init = (ulg)curr + WIN_INIT - s->high_water; 1588 if (init > s->window_size - s->high_water) 1589 init = s->window_size - s->high_water; 1590 zmemzero(s->window + s->high_water, (unsigned)init); 1591 s->high_water += init; 1592 } 1593 } 1594 1595 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1596 "not enough room for search"); 1597 } 1598 1599 /* =========================================================================== 1600 * Flush the current block, with given end-of-file flag. 1601 * IN assertion: strstart is set to the end of the current match. 1602 */ 1603 #define FLUSH_BLOCK_ONLY(s, last) { \ 1604 _tr_flush_block(s, (s->block_start >= 0L ? \ 1605 (charf *)&s->window[(unsigned)s->block_start] : \ 1606 (charf *)Z_NULL), \ 1607 (ulg)((long)s->strstart - s->block_start), \ 1608 (last)); \ 1609 s->block_start = s->strstart; \ 1610 flush_pending(s->strm); \ 1611 Tracev((stderr,"[FLUSH]")); \ 1612 } 1613 1614 /* Same but force premature exit if necessary. */ 1615 #define FLUSH_BLOCK(s, last) { \ 1616 FLUSH_BLOCK_ONLY(s, last); \ 1617 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1618 } 1619 1620 /* Maximum stored block length in deflate format (not including header). */ 1621 #define MAX_STORED 65535 1622 1623 /* Minimum of a and b. */ 1624 #define MIN(a, b) ((a) > (b) ? (b) : (a)) 1625 1626 /* =========================================================================== 1627 * Copy without compression as much as possible from the input stream, return 1628 * the current block state. 1629 * 1630 * In case deflateParams() is used to later switch to a non-zero compression 1631 * level, s->matches (otherwise unused when storing) keeps track of the number 1632 * of hash table slides to perform. If s->matches is 1, then one hash table 1633 * slide will be done when switching. If s->matches is 2, the maximum value 1634 * allowed here, then the hash table will be cleared, since two or more slides 1635 * is the same as a clear. 1636 * 1637 * deflate_stored() is written to minimize the number of times an input byte is 1638 * copied. It is most efficient with large input and output buffers, which 1639 * maximizes the opportunites to have a single copy from next_in to next_out. 1640 */ 1641 local block_state deflate_stored(s, flush) 1642 deflate_state *s; 1643 int flush; 1644 { 1645 /* Smallest worthy block size when not flushing or finishing. By default 1646 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For 1647 * large input and output buffers, the stored block size will be larger. 1648 */ 1649 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size); 1650 1651 /* Copy as many min_block or larger stored blocks directly to next_out as 1652 * possible. If flushing, copy the remaining available input to next_out as 1653 * stored blocks, if there is enough space. 1654 */ 1655 unsigned len, left, have, last = 0; 1656 unsigned used = s->strm->avail_in; 1657 do { 1658 /* Set len to the maximum size block that we can copy directly with the 1659 * available input data and output space. Set left to how much of that 1660 * would be copied from what's left in the window. 1661 */ 1662 len = MAX_STORED; /* maximum deflate stored block length */ 1663 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1664 if (s->strm->avail_out < have) /* need room for header */ 1665 break; 1666 /* maximum stored block length that will fit in avail_out: */ 1667 have = s->strm->avail_out - have; 1668 left = s->strstart - s->block_start; /* bytes left in window */ 1669 if (len > (ulg)left + s->strm->avail_in) 1670 len = left + s->strm->avail_in; /* limit len to the input */ 1671 if (len > have) 1672 len = have; /* limit len to the output */ 1673 1674 /* If the stored block would be less than min_block in length, or if 1675 * unable to copy all of the available input when flushing, then try 1676 * copying to the window and the pending buffer instead. Also don't 1677 * write an empty block when flushing -- deflate() does that. 1678 */ 1679 if (len < min_block && ((len == 0 && flush != Z_FINISH) || 1680 flush == Z_NO_FLUSH || 1681 len != left + s->strm->avail_in)) 1682 break; 1683 1684 /* Make a dummy stored block in pending to get the header bytes, 1685 * including any pending bits. This also updates the debugging counts. 1686 */ 1687 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0; 1688 _tr_stored_block(s, (char *)0, 0L, last); 1689 1690 /* Replace the lengths in the dummy stored block with len. */ 1691 s->pending_buf[s->pending - 4] = len; 1692 s->pending_buf[s->pending - 3] = len >> 8; 1693 s->pending_buf[s->pending - 2] = ~len; 1694 s->pending_buf[s->pending - 1] = ~len >> 8; 1695 1696 /* Write the stored block header bytes. */ 1697 flush_pending(s->strm); 1698 1699 #ifdef ZLIB_DEBUG 1700 /* Update debugging counts for the data about to be copied. */ 1701 s->compressed_len += len << 3; 1702 s->bits_sent += len << 3; 1703 #endif 1704 1705 /* Copy uncompressed bytes from the window to next_out. */ 1706 if (left) { 1707 if (left > len) 1708 left = len; 1709 zmemcpy(s->strm->next_out, s->window + s->block_start, left); 1710 s->strm->next_out += left; 1711 s->strm->avail_out -= left; 1712 s->strm->total_out += left; 1713 s->block_start += left; 1714 len -= left; 1715 } 1716 1717 /* Copy uncompressed bytes directly from next_in to next_out, updating 1718 * the check value. 1719 */ 1720 if (len) { 1721 read_buf(s->strm, s->strm->next_out, len); 1722 s->strm->next_out += len; 1723 s->strm->avail_out -= len; 1724 s->strm->total_out += len; 1725 } 1726 } while (last == 0); 1727 1728 /* Update the sliding window with the last s->w_size bytes of the copied 1729 * data, or append all of the copied data to the existing window if less 1730 * than s->w_size bytes were copied. Also update the number of bytes to 1731 * insert in the hash tables, in the event that deflateParams() switches to 1732 * a non-zero compression level. 1733 */ 1734 used -= s->strm->avail_in; /* number of input bytes directly copied */ 1735 if (used) { 1736 /* If any input was used, then no unused input remains in the window, 1737 * therefore s->block_start == s->strstart. 1738 */ 1739 if (used >= s->w_size) { /* supplant the previous history */ 1740 s->matches = 2; /* clear hash */ 1741 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size); 1742 s->strstart = s->w_size; 1743 } 1744 else { 1745 if (s->window_size - s->strstart <= used) { 1746 /* Slide the window down. */ 1747 s->strstart -= s->w_size; 1748 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1749 if (s->matches < 2) 1750 s->matches++; /* add a pending slide_hash() */ 1751 } 1752 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used); 1753 s->strstart += used; 1754 } 1755 s->block_start = s->strstart; 1756 s->insert += MIN(used, s->w_size - s->insert); 1757 } 1758 if (s->high_water < s->strstart) 1759 s->high_water = s->strstart; 1760 1761 /* If the last block was written to next_out, then done. */ 1762 if (last) 1763 return finish_done; 1764 1765 /* If flushing and all input has been consumed, then done. */ 1766 if (flush != Z_NO_FLUSH && flush != Z_FINISH && 1767 s->strm->avail_in == 0 && (long)s->strstart == s->block_start) 1768 return block_done; 1769 1770 /* Fill the window with any remaining input. */ 1771 have = s->window_size - s->strstart - 1; 1772 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) { 1773 /* Slide the window down. */ 1774 s->block_start -= s->w_size; 1775 s->strstart -= s->w_size; 1776 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1777 if (s->matches < 2) 1778 s->matches++; /* add a pending slide_hash() */ 1779 have += s->w_size; /* more space now */ 1780 } 1781 if (have > s->strm->avail_in) 1782 have = s->strm->avail_in; 1783 if (have) { 1784 read_buf(s->strm, s->window + s->strstart, have); 1785 s->strstart += have; 1786 } 1787 if (s->high_water < s->strstart) 1788 s->high_water = s->strstart; 1789 1790 /* There was not enough avail_out to write a complete worthy or flushed 1791 * stored block to next_out. Write a stored block to pending instead, if we 1792 * have enough input for a worthy block, or if flushing and there is enough 1793 * room for the remaining input as a stored block in the pending buffer. 1794 */ 1795 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1796 /* maximum stored block length that will fit in pending: */ 1797 have = MIN(s->pending_buf_size - have, MAX_STORED); 1798 min_block = MIN(have, s->w_size); 1799 left = s->strstart - s->block_start; 1800 if (left >= min_block || 1801 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH && 1802 s->strm->avail_in == 0 && left <= have)) { 1803 len = MIN(left, have); 1804 last = flush == Z_FINISH && s->strm->avail_in == 0 && 1805 len == left ? 1 : 0; 1806 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last); 1807 s->block_start += len; 1808 flush_pending(s->strm); 1809 } 1810 1811 /* We've done all we can with the available input and output. */ 1812 return last ? finish_started : need_more; 1813 } 1814 1815 /* =========================================================================== 1816 * Compress as much as possible from the input stream, return the current 1817 * block state. 1818 * This function does not perform lazy evaluation of matches and inserts 1819 * new strings in the dictionary only for unmatched strings or for short 1820 * matches. It is used only for the fast compression options. 1821 */ 1822 local block_state deflate_fast(s, flush) 1823 deflate_state *s; 1824 int flush; 1825 { 1826 IPos hash_head; /* head of the hash chain */ 1827 int bflush; /* set if current block must be flushed */ 1828 1829 for (;;) { 1830 /* Make sure that we always have enough lookahead, except 1831 * at the end of the input file. We need MAX_MATCH bytes 1832 * for the next match, plus MIN_MATCH bytes to insert the 1833 * string following the next match. 1834 */ 1835 if (s->lookahead < MIN_LOOKAHEAD) { 1836 fill_window(s); 1837 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1838 return need_more; 1839 } 1840 if (s->lookahead == 0) break; /* flush the current block */ 1841 } 1842 1843 /* Insert the string window[strstart .. strstart+2] in the 1844 * dictionary, and set hash_head to the head of the hash chain: 1845 */ 1846 hash_head = NIL; 1847 if (s->lookahead >= MIN_MATCH) { 1848 INSERT_STRING(s, s->strstart, hash_head); 1849 } 1850 1851 /* Find the longest match, discarding those <= prev_length. 1852 * At this point we have always match_length < MIN_MATCH 1853 */ 1854 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1855 /* To simplify the code, we prevent matches with the string 1856 * of window index 0 (in particular we have to avoid a match 1857 * of the string with itself at the start of the input file). 1858 */ 1859 s->match_length = longest_match (s, hash_head); 1860 /* longest_match() sets match_start */ 1861 } 1862 if (s->match_length >= MIN_MATCH) { 1863 check_match(s, s->strstart, s->match_start, s->match_length); 1864 1865 _tr_tally_dist(s, s->strstart - s->match_start, 1866 s->match_length - MIN_MATCH, bflush); 1867 1868 s->lookahead -= s->match_length; 1869 1870 /* Insert new strings in the hash table only if the match length 1871 * is not too large. This saves time but degrades compression. 1872 */ 1873 #ifndef FASTEST 1874 if (s->match_length <= s->max_insert_length && 1875 s->lookahead >= MIN_MATCH) { 1876 s->match_length--; /* string at strstart already in table */ 1877 do { 1878 s->strstart++; 1879 INSERT_STRING(s, s->strstart, hash_head); 1880 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1881 * always MIN_MATCH bytes ahead. 1882 */ 1883 } while (--s->match_length != 0); 1884 s->strstart++; 1885 } else 1886 #endif 1887 { 1888 s->strstart += s->match_length; 1889 s->match_length = 0; 1890 s->ins_h = s->window[s->strstart]; 1891 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); 1892 #if MIN_MATCH != 3 1893 Call UPDATE_HASH() MIN_MATCH-3 more times 1894 #endif 1895 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1896 * matter since it will be recomputed at next deflate call. 1897 */ 1898 } 1899 } else { 1900 /* No match, output a literal byte */ 1901 Tracevv((stderr,"%c", s->window[s->strstart])); 1902 _tr_tally_lit (s, s->window[s->strstart], bflush); 1903 s->lookahead--; 1904 s->strstart++; 1905 } 1906 if (bflush) FLUSH_BLOCK(s, 0); 1907 } 1908 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1909 if (flush == Z_FINISH) { 1910 FLUSH_BLOCK(s, 1); 1911 return finish_done; 1912 } 1913 if (s->last_lit) 1914 FLUSH_BLOCK(s, 0); 1915 return block_done; 1916 } 1917 1918 #ifndef FASTEST 1919 /* =========================================================================== 1920 * Same as above, but achieves better compression. We use a lazy 1921 * evaluation for matches: a match is finally adopted only if there is 1922 * no better match at the next window position. 1923 */ 1924 local block_state deflate_slow(s, flush) 1925 deflate_state *s; 1926 int flush; 1927 { 1928 IPos hash_head; /* head of hash chain */ 1929 int bflush; /* set if current block must be flushed */ 1930 1931 /* Process the input block. */ 1932 for (;;) { 1933 /* Make sure that we always have enough lookahead, except 1934 * at the end of the input file. We need MAX_MATCH bytes 1935 * for the next match, plus MIN_MATCH bytes to insert the 1936 * string following the next match. 1937 */ 1938 if (s->lookahead < MIN_LOOKAHEAD) { 1939 fill_window(s); 1940 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1941 return need_more; 1942 } 1943 if (s->lookahead == 0) break; /* flush the current block */ 1944 } 1945 1946 /* Insert the string window[strstart .. strstart+2] in the 1947 * dictionary, and set hash_head to the head of the hash chain: 1948 */ 1949 hash_head = NIL; 1950 if (s->lookahead >= MIN_MATCH) { 1951 INSERT_STRING(s, s->strstart, hash_head); 1952 } 1953 1954 /* Find the longest match, discarding those <= prev_length. 1955 */ 1956 s->prev_length = s->match_length, s->prev_match = s->match_start; 1957 s->match_length = MIN_MATCH-1; 1958 1959 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1960 s->strstart - hash_head <= MAX_DIST(s)) { 1961 /* To simplify the code, we prevent matches with the string 1962 * of window index 0 (in particular we have to avoid a match 1963 * of the string with itself at the start of the input file). 1964 */ 1965 s->match_length = longest_match (s, hash_head); 1966 /* longest_match() sets match_start */ 1967 1968 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1969 #if TOO_FAR <= 32767 1970 || (s->match_length == MIN_MATCH && 1971 s->strstart - s->match_start > TOO_FAR) 1972 #endif 1973 )) { 1974 1975 /* If prev_match is also MIN_MATCH, match_start is garbage 1976 * but we will ignore the current match anyway. 1977 */ 1978 s->match_length = MIN_MATCH-1; 1979 } 1980 } 1981 /* If there was a match at the previous step and the current 1982 * match is not better, output the previous match: 1983 */ 1984 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1985 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1986 /* Do not insert strings in hash table beyond this. */ 1987 1988 check_match(s, s->strstart-1, s->prev_match, s->prev_length); 1989 1990 _tr_tally_dist(s, s->strstart -1 - s->prev_match, 1991 s->prev_length - MIN_MATCH, bflush); 1992 1993 /* Insert in hash table all strings up to the end of the match. 1994 * strstart-1 and strstart are already inserted. If there is not 1995 * enough lookahead, the last two strings are not inserted in 1996 * the hash table. 1997 */ 1998 s->lookahead -= s->prev_length-1; 1999 s->prev_length -= 2; 2000 do { 2001 if (++s->strstart <= max_insert) { 2002 INSERT_STRING(s, s->strstart, hash_head); 2003 } 2004 } while (--s->prev_length != 0); 2005 s->match_available = 0; 2006 s->match_length = MIN_MATCH-1; 2007 s->strstart++; 2008 2009 if (bflush) FLUSH_BLOCK(s, 0); 2010 2011 } else if (s->match_available) { 2012 /* If there was no match at the previous position, output a 2013 * single literal. If there was a match but the current match 2014 * is longer, truncate the previous match to a single literal. 2015 */ 2016 Tracevv((stderr,"%c", s->window[s->strstart-1])); 2017 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 2018 if (bflush) { 2019 FLUSH_BLOCK_ONLY(s, 0); 2020 } 2021 s->strstart++; 2022 s->lookahead--; 2023 if (s->strm->avail_out == 0) return need_more; 2024 } else { 2025 /* There is no previous match to compare with, wait for 2026 * the next step to decide. 2027 */ 2028 s->match_available = 1; 2029 s->strstart++; 2030 s->lookahead--; 2031 } 2032 } 2033 Assert (flush != Z_NO_FLUSH, "no flush?"); 2034 if (s->match_available) { 2035 Tracevv((stderr,"%c", s->window[s->strstart-1])); 2036 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 2037 s->match_available = 0; 2038 } 2039 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 2040 if (flush == Z_FINISH) { 2041 FLUSH_BLOCK(s, 1); 2042 return finish_done; 2043 } 2044 if (s->last_lit) 2045 FLUSH_BLOCK(s, 0); 2046 return block_done; 2047 } 2048 #endif /* FASTEST */ 2049 2050 /* =========================================================================== 2051 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 2052 * one. Do not maintain a hash table. (It will be regenerated if this run of 2053 * deflate switches away from Z_RLE.) 2054 */ 2055 local block_state deflate_rle(s, flush) 2056 deflate_state *s; 2057 int flush; 2058 { 2059 int bflush; /* set if current block must be flushed */ 2060 uInt prev; /* byte at distance one to match */ 2061 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 2062 2063 for (;;) { 2064 /* Make sure that we always have enough lookahead, except 2065 * at the end of the input file. We need MAX_MATCH bytes 2066 * for the longest run, plus one for the unrolled loop. 2067 */ 2068 if (s->lookahead <= MAX_MATCH) { 2069 fill_window(s); 2070 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 2071 return need_more; 2072 } 2073 if (s->lookahead == 0) break; /* flush the current block */ 2074 } 2075 2076 /* See how many times the previous byte repeats */ 2077 s->match_length = 0; 2078 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 2079 scan = s->window + s->strstart - 1; 2080 prev = *scan; 2081 if (prev == *++scan && prev == *++scan && prev == *++scan) { 2082 strend = s->window + s->strstart + MAX_MATCH; 2083 do { 2084 } while (prev == *++scan && prev == *++scan && 2085 prev == *++scan && prev == *++scan && 2086 prev == *++scan && prev == *++scan && 2087 prev == *++scan && prev == *++scan && 2088 scan < strend); 2089 s->match_length = MAX_MATCH - (uInt)(strend - scan); 2090 if (s->match_length > s->lookahead) 2091 s->match_length = s->lookahead; 2092 } 2093 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan"); 2094 } 2095 2096 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 2097 if (s->match_length >= MIN_MATCH) { 2098 check_match(s, s->strstart, s->strstart - 1, s->match_length); 2099 2100 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 2101 2102 s->lookahead -= s->match_length; 2103 s->strstart += s->match_length; 2104 s->match_length = 0; 2105 } else { 2106 /* No match, output a literal byte */ 2107 Tracevv((stderr,"%c", s->window[s->strstart])); 2108 _tr_tally_lit (s, s->window[s->strstart], bflush); 2109 s->lookahead--; 2110 s->strstart++; 2111 } 2112 if (bflush) FLUSH_BLOCK(s, 0); 2113 } 2114 s->insert = 0; 2115 if (flush == Z_FINISH) { 2116 FLUSH_BLOCK(s, 1); 2117 return finish_done; 2118 } 2119 if (s->last_lit) 2120 FLUSH_BLOCK(s, 0); 2121 return block_done; 2122 } 2123 2124 /* =========================================================================== 2125 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 2126 * (It will be regenerated if this run of deflate switches away from Huffman.) 2127 */ 2128 local block_state deflate_huff(s, flush) 2129 deflate_state *s; 2130 int flush; 2131 { 2132 int bflush; /* set if current block must be flushed */ 2133 2134 for (;;) { 2135 /* Make sure that we have a literal to write. */ 2136 if (s->lookahead == 0) { 2137 fill_window(s); 2138 if (s->lookahead == 0) { 2139 if (flush == Z_NO_FLUSH) 2140 return need_more; 2141 break; /* flush the current block */ 2142 } 2143 } 2144 2145 /* Output a literal byte */ 2146 s->match_length = 0; 2147 Tracevv((stderr,"%c", s->window[s->strstart])); 2148 _tr_tally_lit (s, s->window[s->strstart], bflush); 2149 s->lookahead--; 2150 s->strstart++; 2151 if (bflush) FLUSH_BLOCK(s, 0); 2152 } 2153 s->insert = 0; 2154 if (flush == Z_FINISH) { 2155 FLUSH_BLOCK(s, 1); 2156 return finish_done; 2157 } 2158 if (s->last_lit) 2159 FLUSH_BLOCK(s, 0); 2160 return block_done; 2161 } 2162