deflate.c revision ac3d58cff7c80b0ef56bf55130d91da17cbaa3c4
1/* deflate.c -- compress data using the deflation algorithm 2 * Copyright (C) 1995-2013 Jean-loup Gailly and Mark Adler 3 * For conditions of distribution and use, see copyright notice in zlib.h 4 */ 5 6/* 7 * ALGORITHM 8 * 9 * The "deflation" process depends on being able to identify portions 10 * of the input text which are identical to earlier input (within a 11 * sliding window trailing behind the input currently being processed). 12 * 13 * The most straightforward technique turns out to be the fastest for 14 * most input files: try all possible matches and select the longest. 15 * The key feature of this algorithm is that insertions into the string 16 * dictionary are very simple and thus fast, and deletions are avoided 17 * completely. Insertions are performed at each input character, whereas 18 * string matches are performed only when the previous match ends. So it 19 * is preferable to spend more time in matches to allow very fast string 20 * insertions and avoid deletions. The matching algorithm for small 21 * strings is inspired from that of Rabin & Karp. A brute force approach 22 * is used to find longer strings when a small match has been found. 23 * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze 24 * (by Leonid Broukhis). 25 * A previous version of this file used a more sophisticated algorithm 26 * (by Fiala and Greene) which is guaranteed to run in linear amortized 27 * time, but has a larger average cost, uses more memory and is patented. 28 * However the F&G algorithm may be faster for some highly redundant 29 * files if the parameter max_chain_length (described below) is too large. 30 * 31 * ACKNOWLEDGEMENTS 32 * 33 * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and 34 * I found it in 'freeze' written by Leonid Broukhis. 35 * Thanks to many people for bug reports and testing. 36 * 37 * REFERENCES 38 * 39 * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification". 40 * Available in http://tools.ietf.org/html/rfc1951 41 * 42 * A description of the Rabin and Karp algorithm is given in the book 43 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252. 44 * 45 * Fiala,E.R., and Greene,D.H. 46 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595 47 * 48 */ 49 50/* @(#) $Id$ */ 51 52#include "deflate.h" 53 54const char deflate_copyright[] = 55 " deflate 1.2.8 Copyright 1995-2013 Jean-loup Gailly and Mark Adler "; 56/* 57 If you use the zlib library in a product, an acknowledgment is welcome 58 in the documentation of your product. If for some reason you cannot 59 include such an acknowledgment, I would appreciate that you keep this 60 copyright string in the executable of your product. 61 */ 62 63/* =========================================================================== 64 * Function prototypes. 65 */ 66typedef enum { 67 need_more, /* block not completed, need more input or more output */ 68 block_done, /* block flush performed */ 69 finish_started, /* finish started, need only more output at next deflate */ 70 finish_done /* finish done, accept no more input or output */ 71} block_state; 72 73typedef block_state (*compress_func) OF((deflate_state *s, int flush)); 74/* Compression function. Returns the block state after the call. */ 75 76local void fill_window OF((deflate_state *s)); 77local block_state deflate_stored OF((deflate_state *s, int flush)); 78local block_state deflate_fast OF((deflate_state *s, int flush)); 79#ifndef FASTEST 80local block_state deflate_slow OF((deflate_state *s, int flush)); 81#endif 82local block_state deflate_rle OF((deflate_state *s, int flush)); 83local block_state deflate_huff OF((deflate_state *s, int flush)); 84local void lm_init OF((deflate_state *s)); 85local void putShortMSB OF((deflate_state *s, uInt b)); 86local void flush_pending OF((z_streamp strm)); 87local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size)); 88#ifdef ASMV 89 void match_init OF((void)); /* asm code initialization */ 90 uInt longest_match OF((deflate_state *s, IPos cur_match)); 91#else 92local uInt longest_match OF((deflate_state *s, IPos cur_match)); 93#endif 94 95#ifdef DEBUG 96local 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 */ 117typedef 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 126local 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 131local 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#define EQUAL 0 152/* result of memcmp for equal strings */ 153 154#ifndef NO_DUMMY_DECL 155struct static_tree_desc_s {int dummy;}; /* for buggy compilers */ 156#endif 157 158/* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */ 159#define RANK(f) (((f) << 1) - ((f) > 4 ? 9 : 0)) 160 161/* =========================================================================== 162 * Update a hash value with the given input byte 163 * IN assertion: all calls to to UPDATE_HASH are made with consecutive 164 * input characters, so that a running hash key can be computed from the 165 * previous key instead of complete recalculation each time. 166 */ 167#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask) 168 169 170/* =========================================================================== 171 * Insert string str in the dictionary and set match_head to the previous head 172 * of the hash chain (the most recent string with same hash key). Return 173 * the previous length of the hash chain. 174 * If this file is compiled with -DFASTEST, the compression level is forced 175 * to 1, and no hash chains are maintained. 176 * IN assertion: all calls to to INSERT_STRING are made with consecutive 177 * input characters and the first MIN_MATCH bytes of str are valid 178 * (except for the last MIN_MATCH-1 bytes of the input file). 179 */ 180#ifdef FASTEST 181#define INSERT_STRING(s, str, match_head) \ 182 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 183 match_head = s->head[s->ins_h], \ 184 s->head[s->ins_h] = (Pos)(str)) 185#else 186#define INSERT_STRING(s, str, match_head) \ 187 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 188 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ 189 s->head[s->ins_h] = (Pos)(str)) 190#endif 191 192/* =========================================================================== 193 * Initialize the hash table (avoiding 64K overflow for 16 bit systems). 194 * prev[] will be initialized on the fly. 195 */ 196#define CLEAR_HASH(s) \ 197 s->head[s->hash_size-1] = NIL; \ 198 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head)); 199 200/* ========================================================================= */ 201int ZEXPORT deflateInit_( 202 z_streamp strm, 203 int level, 204 const char *version, 205 int stream_size) 206{ 207 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, 208 Z_DEFAULT_STRATEGY, version, stream_size); 209 /* To do: ignore strm->next_in if we use it as window */ 210} 211 212/* ========================================================================= */ 213int ZEXPORT deflateInit2_( 214 z_streamp strm, 215 int level, 216 int method, 217 int windowBits, 218 int memLevel, 219 int strategy, 220 const char *version, 221 int stream_size) 222{ 223 deflate_state *s; 224 int wrap = 1; 225 static const char my_version[] = ZLIB_VERSION; 226 227 ushf *overlay; 228 /* We overlay pending_buf and d_buf+l_buf. This works since the average 229 * output size for (length,distance) codes is <= 24 bits. 230 */ 231 232 if (version == Z_NULL || version[0] != my_version[0] || 233 stream_size != sizeof(z_stream)) { 234 return Z_VERSION_ERROR; 235 } 236 if (strm == Z_NULL) return Z_STREAM_ERROR; 237 238 strm->msg = Z_NULL; 239 if (strm->zalloc == (alloc_func)0) { 240#ifdef Z_SOLO 241 return Z_STREAM_ERROR; 242#else 243 strm->zalloc = zcalloc; 244 strm->opaque = (voidpf)0; 245#endif 246 } 247 if (strm->zfree == (free_func)0) 248#ifdef Z_SOLO 249 return Z_STREAM_ERROR; 250#else 251 strm->zfree = zcfree; 252#endif 253 254#ifdef FASTEST 255 if (level != 0) level = 1; 256#else 257 if (level == Z_DEFAULT_COMPRESSION) level = 6; 258#endif 259 260 if (windowBits < 0) { /* suppress zlib wrapper */ 261 wrap = 0; 262 windowBits = -windowBits; 263 } 264#ifdef GZIP 265 else if (windowBits > 15) { 266 wrap = 2; /* write gzip wrapper instead */ 267 windowBits -= 16; 268 } 269#endif 270 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 271 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 272 strategy < 0 || strategy > Z_FIXED) { 273 return Z_STREAM_ERROR; 274 } 275 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 276 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 277 if (s == Z_NULL) return Z_MEM_ERROR; 278 strm->state = (struct internal_state FAR *)s; 279 s->strm = strm; 280 281 s->wrap = wrap; 282 s->gzhead = Z_NULL; 283 s->w_bits = windowBits; 284 s->w_size = 1 << s->w_bits; 285 s->w_mask = s->w_size - 1; 286 287 s->hash_bits = memLevel + 7; 288 s->hash_size = 1 << s->hash_bits; 289 s->hash_mask = s->hash_size - 1; 290 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); 291 292 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 293 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 294 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 295 296 s->high_water = 0; /* nothing written to s->window yet */ 297 298 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 299 300 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); 301 s->pending_buf = (uchf *) overlay; 302 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); 303 304 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 305 s->pending_buf == Z_NULL) { 306 s->status = FINISH_STATE; 307 strm->msg = ERR_MSG(Z_MEM_ERROR); 308 deflateEnd (strm); 309 return Z_MEM_ERROR; 310 } 311 s->d_buf = overlay + s->lit_bufsize/sizeof(ush); 312 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; 313 314 s->level = level; 315 s->strategy = strategy; 316 s->method = (Byte)method; 317 318 return deflateReset(strm); 319} 320 321/* ========================================================================= */ 322int ZEXPORT deflateSetDictionary ( 323 z_streamp strm, 324 const Bytef *dictionary, 325 uInt dictLength) 326{ 327 deflate_state *s; 328 uInt str, n; 329 int wrap; 330 unsigned avail; 331 z_const unsigned char *next; 332 333 if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL) 334 return Z_STREAM_ERROR; 335 s = strm->state; 336 wrap = s->wrap; 337 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) 338 return Z_STREAM_ERROR; 339 340 /* when using zlib wrappers, compute Adler-32 for provided dictionary */ 341 if (wrap == 1) 342 strm->adler = adler32(strm->adler, dictionary, dictLength); 343 s->wrap = 0; /* avoid computing Adler-32 in read_buf */ 344 345 /* if dictionary would fill window, just replace the history */ 346 if (dictLength >= s->w_size) { 347 if (wrap == 0) { /* already empty otherwise */ 348 CLEAR_HASH(s); 349 s->strstart = 0; 350 s->block_start = 0L; 351 s->insert = 0; 352 } 353 dictionary += dictLength - s->w_size; /* use the tail */ 354 dictLength = s->w_size; 355 } 356 357 /* insert dictionary into window and hash */ 358 avail = strm->avail_in; 359 next = strm->next_in; 360 strm->avail_in = dictLength; 361 strm->next_in = (z_const Bytef *)dictionary; 362 fill_window(s); 363 while (s->lookahead >= MIN_MATCH) { 364 str = s->strstart; 365 n = s->lookahead - (MIN_MATCH-1); 366 do { 367 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 368#ifndef FASTEST 369 s->prev[str & s->w_mask] = s->head[s->ins_h]; 370#endif 371 s->head[s->ins_h] = (Pos)str; 372 str++; 373 } while (--n); 374 s->strstart = str; 375 s->lookahead = MIN_MATCH-1; 376 fill_window(s); 377 } 378 s->strstart += s->lookahead; 379 s->block_start = (long)s->strstart; 380 s->insert = s->lookahead; 381 s->lookahead = 0; 382 s->match_length = s->prev_length = MIN_MATCH-1; 383 s->match_available = 0; 384 strm->next_in = next; 385 strm->avail_in = avail; 386 s->wrap = wrap; 387 return Z_OK; 388} 389 390/* ========================================================================= */ 391int ZEXPORT deflateResetKeep ( 392 z_streamp strm) 393{ 394 deflate_state *s; 395 396 if (strm == Z_NULL || strm->state == Z_NULL || 397 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) { 398 return Z_STREAM_ERROR; 399 } 400 401 strm->total_in = strm->total_out = 0; 402 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 403 strm->data_type = Z_UNKNOWN; 404 405 s = (deflate_state *)strm->state; 406 s->pending = 0; 407 s->pending_out = s->pending_buf; 408 409 if (s->wrap < 0) { 410 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 411 } 412 s->status = s->wrap ? INIT_STATE : BUSY_STATE; 413 strm->adler = 414#ifdef GZIP 415 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 416#endif 417 adler32(0L, Z_NULL, 0); 418 s->last_flush = Z_NO_FLUSH; 419 420 _tr_init(s); 421 422 return Z_OK; 423} 424 425/* ========================================================================= */ 426int ZEXPORT deflateReset ( 427 z_streamp strm) 428{ 429 int ret; 430 431 ret = deflateResetKeep(strm); 432 if (ret == Z_OK) 433 lm_init(strm->state); 434 return ret; 435} 436 437/* ========================================================================= */ 438int ZEXPORT deflateSetHeader (strm, head) 439 z_streamp strm; 440 gz_headerp head; 441{ 442 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 443 if (strm->state->wrap != 2) return Z_STREAM_ERROR; 444 strm->state->gzhead = head; 445 return Z_OK; 446} 447 448/* ========================================================================= */ 449int ZEXPORT deflatePending ( 450 z_streamp strm, 451 unsigned *pending, 452 int *bits) 453{ 454 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 455 if (pending != Z_NULL) 456 *pending = strm->state->pending; 457 if (bits != Z_NULL) 458 *bits = strm->state->bi_valid; 459 return Z_OK; 460} 461 462/* ========================================================================= */ 463int ZEXPORT deflatePrime (strm, bits, value) 464 z_streamp strm; 465 int bits; 466 int value; 467{ 468 deflate_state *s; 469 int put; 470 471 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 472 s = strm->state; 473 if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3)) 474 return Z_BUF_ERROR; 475 do { 476 put = Buf_size - s->bi_valid; 477 if (put > bits) 478 put = bits; 479 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); 480 s->bi_valid += put; 481 _tr_flush_bits(s); 482 value >>= put; 483 bits -= put; 484 } while (bits); 485 return Z_OK; 486} 487 488/* ========================================================================= */ 489int ZEXPORT deflateParams( 490 z_streamp strm, 491 int level, 492 int strategy) 493{ 494 deflate_state *s; 495 compress_func func; 496 int err = Z_OK; 497 498 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 499 s = strm->state; 500 501#ifdef FASTEST 502 if (level != 0) level = 1; 503#else 504 if (level == Z_DEFAULT_COMPRESSION) level = 6; 505#endif 506 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 507 return Z_STREAM_ERROR; 508 } 509 func = configuration_table[s->level].func; 510 511 if ((strategy != s->strategy || func != configuration_table[level].func) && 512 strm->total_in != 0) { 513 /* Flush the last buffer: */ 514 err = deflate(strm, Z_BLOCK); 515 if (err == Z_BUF_ERROR && s->pending == 0) 516 err = Z_OK; 517 } 518 if (s->level != level) { 519 s->level = level; 520 s->max_lazy_match = configuration_table[level].max_lazy; 521 s->good_match = configuration_table[level].good_length; 522 s->nice_match = configuration_table[level].nice_length; 523 s->max_chain_length = configuration_table[level].max_chain; 524 } 525 s->strategy = strategy; 526 return err; 527} 528 529/* ========================================================================= */ 530int ZEXPORT deflateTune( 531 z_streamp strm, 532 int good_length, 533 int max_lazy, 534 int nice_length, 535 int max_chain) 536{ 537 deflate_state *s; 538 539 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 540 s = strm->state; 541 s->good_match = good_length; 542 s->max_lazy_match = max_lazy; 543 s->nice_match = nice_length; 544 s->max_chain_length = max_chain; 545 return Z_OK; 546} 547 548/* ========================================================================= 549 * For the default windowBits of 15 and memLevel of 8, this function returns 550 * a close to exact, as well as small, upper bound on the compressed size. 551 * They are coded as constants here for a reason--if the #define's are 552 * changed, then this function needs to be changed as well. The return 553 * value for 15 and 8 only works for those exact settings. 554 * 555 * For any setting other than those defaults for windowBits and memLevel, 556 * the value returned is a conservative worst case for the maximum expansion 557 * resulting from using fixed blocks instead of stored blocks, which deflate 558 * can emit on compressed data for some combinations of the parameters. 559 * 560 * This function could be more sophisticated to provide closer upper bounds for 561 * every combination of windowBits and memLevel. But even the conservative 562 * upper bound of about 14% expansion does not seem onerous for output buffer 563 * allocation. 564 */ 565uLong ZEXPORT deflateBound( 566 z_streamp strm, 567 uLong sourceLen) 568{ 569 deflate_state *s; 570 uLong complen, wraplen; 571 Bytef *str; 572 573 /* conservative upper bound for compressed data */ 574 complen = sourceLen + 575 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5; 576 577 /* if can't get parameters, return conservative bound plus zlib wrapper */ 578 if (strm == Z_NULL || strm->state == Z_NULL) 579 return complen + 6; 580 581 /* compute wrapper length */ 582 s = strm->state; 583 switch (s->wrap) { 584 case 0: /* raw deflate */ 585 wraplen = 0; 586 break; 587 case 1: /* zlib wrapper */ 588 wraplen = 6 + (s->strstart ? 4 : 0); 589 break; 590 case 2: /* gzip wrapper */ 591 wraplen = 18; 592 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 593 if (s->gzhead->extra != Z_NULL) 594 wraplen += 2 + s->gzhead->extra_len; 595 str = s->gzhead->name; 596 if (str != Z_NULL) 597 do { 598 wraplen++; 599 } while (*str++); 600 str = s->gzhead->comment; 601 if (str != Z_NULL) 602 do { 603 wraplen++; 604 } while (*str++); 605 if (s->gzhead->hcrc) 606 wraplen += 2; 607 } 608 break; 609 default: /* for compiler happiness */ 610 wraplen = 6; 611 } 612 613 /* if not default parameters, return conservative bound */ 614 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 615 return complen + wraplen; 616 617 /* default settings: return tight bound for that case */ 618 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 619 (sourceLen >> 25) + 13 - 6 + wraplen; 620} 621 622/* ========================================================================= 623 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 624 * IN assertion: the stream state is correct and there is enough room in 625 * pending_buf. 626 */ 627local void putShortMSB ( 628 deflate_state *s, 629 uInt b) 630{ 631 put_byte(s, (Byte)(b >> 8)); 632 put_byte(s, (Byte)(b & 0xff)); 633} 634 635/* ========================================================================= 636 * Flush as much pending output as possible. All deflate() output goes 637 * through this function so some applications may wish to modify it 638 * to avoid allocating a large strm->next_out buffer and copying into it. 639 * (See also read_buf()). 640 */ 641local void flush_pending( 642 z_streamp strm) 643{ 644 unsigned len; 645 deflate_state *s = strm->state; 646 647 _tr_flush_bits(s); 648 len = s->pending; 649 if (len > strm->avail_out) len = strm->avail_out; 650 if (len == 0) return; 651 652 zmemcpy(strm->next_out, s->pending_out, len); 653 strm->next_out += len; 654 s->pending_out += len; 655 strm->total_out += len; 656 strm->avail_out -= len; 657 s->pending -= len; 658 if (s->pending == 0) { 659 s->pending_out = s->pending_buf; 660 } 661} 662 663/* ========================================================================= */ 664int ZEXPORT deflate ( 665 z_streamp strm, 666 int flush) 667{ 668 int old_flush; /* value of flush param for previous deflate call */ 669 deflate_state *s; 670 671 if (strm == Z_NULL || strm->state == Z_NULL || 672 flush > Z_BLOCK || flush < 0) { 673 return Z_STREAM_ERROR; 674 } 675 s = strm->state; 676 677 if (strm->next_out == Z_NULL || 678 (strm->next_in == Z_NULL && strm->avail_in != 0) || 679 (s->status == FINISH_STATE && flush != Z_FINISH)) { 680 ERR_RETURN(strm, Z_STREAM_ERROR); 681 } 682 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 683 684 s->strm = strm; /* just in case */ 685 old_flush = s->last_flush; 686 s->last_flush = flush; 687 688 /* Write the header */ 689 if (s->status == INIT_STATE) { 690#ifdef GZIP 691 if (s->wrap == 2) { 692 strm->adler = crc32(0L, Z_NULL, 0); 693 put_byte(s, 31); 694 put_byte(s, 139); 695 put_byte(s, 8); 696 if (s->gzhead == Z_NULL) { 697 put_byte(s, 0); 698 put_byte(s, 0); 699 put_byte(s, 0); 700 put_byte(s, 0); 701 put_byte(s, 0); 702 put_byte(s, s->level == 9 ? 2 : 703 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 704 4 : 0)); 705 put_byte(s, OS_CODE); 706 s->status = BUSY_STATE; 707 } 708 else { 709 put_byte(s, (s->gzhead->text ? 1 : 0) + 710 (s->gzhead->hcrc ? 2 : 0) + 711 (s->gzhead->extra == Z_NULL ? 0 : 4) + 712 (s->gzhead->name == Z_NULL ? 0 : 8) + 713 (s->gzhead->comment == Z_NULL ? 0 : 16) 714 ); 715 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 716 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 717 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 718 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 719 put_byte(s, s->level == 9 ? 2 : 720 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 721 4 : 0)); 722 put_byte(s, s->gzhead->os & 0xff); 723 if (s->gzhead->extra != Z_NULL) { 724 put_byte(s, s->gzhead->extra_len & 0xff); 725 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 726 } 727 if (s->gzhead->hcrc) 728 strm->adler = crc32(strm->adler, s->pending_buf, 729 s->pending); 730 s->gzindex = 0; 731 s->status = EXTRA_STATE; 732 } 733 } 734 else 735#endif 736 { 737 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; 738 uInt level_flags; 739 740 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 741 level_flags = 0; 742 else if (s->level < 6) 743 level_flags = 1; 744 else if (s->level == 6) 745 level_flags = 2; 746 else 747 level_flags = 3; 748 header |= (level_flags << 6); 749 if (s->strstart != 0) header |= PRESET_DICT; 750 header += 31 - (header % 31); 751 752 s->status = BUSY_STATE; 753 putShortMSB(s, header); 754 755 /* Save the adler32 of the preset dictionary: */ 756 if (s->strstart != 0) { 757 putShortMSB(s, (uInt)(strm->adler >> 16)); 758 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 759 } 760 strm->adler = adler32(0L, Z_NULL, 0); 761 } 762 } 763#ifdef GZIP 764 if (s->status == EXTRA_STATE) { 765 if (s->gzhead->extra != Z_NULL) { 766 uInt beg = s->pending; /* start of bytes to update crc */ 767 768 while (s->gzindex < (s->gzhead->extra_len & 0xffff)) { 769 if (s->pending == s->pending_buf_size) { 770 if (s->gzhead->hcrc && s->pending > beg) 771 strm->adler = crc32(strm->adler, s->pending_buf + beg, 772 s->pending - beg); 773 flush_pending(strm); 774 beg = s->pending; 775 if (s->pending == s->pending_buf_size) 776 break; 777 } 778 put_byte(s, s->gzhead->extra[s->gzindex]); 779 s->gzindex++; 780 } 781 if (s->gzhead->hcrc && s->pending > beg) 782 strm->adler = crc32(strm->adler, s->pending_buf + beg, 783 s->pending - beg); 784 if (s->gzindex == s->gzhead->extra_len) { 785 s->gzindex = 0; 786 s->status = NAME_STATE; 787 } 788 } 789 else 790 s->status = NAME_STATE; 791 } 792 if (s->status == NAME_STATE) { 793 if (s->gzhead->name != Z_NULL) { 794 uInt beg = s->pending; /* start of bytes to update crc */ 795 int val; 796 797 do { 798 if (s->pending == s->pending_buf_size) { 799 if (s->gzhead->hcrc && s->pending > beg) 800 strm->adler = crc32(strm->adler, s->pending_buf + beg, 801 s->pending - beg); 802 flush_pending(strm); 803 beg = s->pending; 804 if (s->pending == s->pending_buf_size) { 805 val = 1; 806 break; 807 } 808 } 809 val = s->gzhead->name[s->gzindex++]; 810 put_byte(s, val); 811 } while (val != 0); 812 if (s->gzhead->hcrc && s->pending > beg) 813 strm->adler = crc32(strm->adler, s->pending_buf + beg, 814 s->pending - beg); 815 if (val == 0) { 816 s->gzindex = 0; 817 s->status = COMMENT_STATE; 818 } 819 } 820 else 821 s->status = COMMENT_STATE; 822 } 823 if (s->status == COMMENT_STATE) { 824 if (s->gzhead->comment != Z_NULL) { 825 uInt beg = s->pending; /* start of bytes to update crc */ 826 int val; 827 828 do { 829 if (s->pending == s->pending_buf_size) { 830 if (s->gzhead->hcrc && s->pending > beg) 831 strm->adler = crc32(strm->adler, s->pending_buf + beg, 832 s->pending - beg); 833 flush_pending(strm); 834 beg = s->pending; 835 if (s->pending == s->pending_buf_size) { 836 val = 1; 837 break; 838 } 839 } 840 val = s->gzhead->comment[s->gzindex++]; 841 put_byte(s, val); 842 } while (val != 0); 843 if (s->gzhead->hcrc && s->pending > beg) 844 strm->adler = crc32(strm->adler, s->pending_buf + beg, 845 s->pending - beg); 846 if (val == 0) 847 s->status = HCRC_STATE; 848 } 849 else 850 s->status = HCRC_STATE; 851 } 852 if (s->status == HCRC_STATE) { 853 if (s->gzhead->hcrc) { 854 if (s->pending + 2 > s->pending_buf_size) 855 flush_pending(strm); 856 if (s->pending + 2 <= s->pending_buf_size) { 857 put_byte(s, (Byte)(strm->adler & 0xff)); 858 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 859 strm->adler = crc32(0L, Z_NULL, 0); 860 s->status = BUSY_STATE; 861 } 862 } 863 else 864 s->status = BUSY_STATE; 865 } 866#endif 867 868 /* Flush as much pending output as possible */ 869 if (s->pending != 0) { 870 flush_pending(strm); 871 if (strm->avail_out == 0) { 872 /* Since avail_out is 0, deflate will be called again with 873 * more output space, but possibly with both pending and 874 * avail_in equal to zero. There won't be anything to do, 875 * but this is not an error situation so make sure we 876 * return OK instead of BUF_ERROR at next call of deflate: 877 */ 878 s->last_flush = -1; 879 return Z_OK; 880 } 881 882 /* Make sure there is something to do and avoid duplicate consecutive 883 * flushes. For repeated and useless calls with Z_FINISH, we keep 884 * returning Z_STREAM_END instead of Z_BUF_ERROR. 885 */ 886 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 887 flush != Z_FINISH) { 888 ERR_RETURN(strm, Z_BUF_ERROR); 889 } 890 891 /* User must not provide more input after the first FINISH: */ 892 if (s->status == FINISH_STATE && strm->avail_in != 0) { 893 ERR_RETURN(strm, Z_BUF_ERROR); 894 } 895 896 /* Start a new block or continue the current one. 897 */ 898 if (strm->avail_in != 0 || s->lookahead != 0 || 899 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 900 block_state bstate; 901 902 bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 903 (s->strategy == Z_RLE ? deflate_rle(s, flush) : 904 (*(configuration_table[s->level].func))(s, flush)); 905 906 if (bstate == finish_started || bstate == finish_done) { 907 s->status = FINISH_STATE; 908 } 909 if (bstate == need_more || bstate == finish_started) { 910 if (strm->avail_out == 0) { 911 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 912 } 913 return Z_OK; 914 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 915 * of deflate should use the same flush parameter to make sure 916 * that the flush is complete. So we don't have to output an 917 * empty block here, this will be done at next call. This also 918 * ensures that for a very small output buffer, we emit at most 919 * one empty block. 920 */ 921 } 922 if (bstate == block_done) { 923 if (flush == Z_PARTIAL_FLUSH) { 924 _tr_align(s); 925 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 926 _tr_stored_block(s, (char*)0, 0L, 0); 927 /* For a full flush, this empty block will be recognized 928 * as a special marker by inflate_sync(). 929 */ 930 if (flush == Z_FULL_FLUSH) { 931 CLEAR_HASH(s); /* forget history */ 932 if (s->lookahead == 0) { 933 s->strstart = 0; 934 s->block_start = 0L; 935 s->insert = 0; 936 } 937 } 938 } 939 flush_pending(strm); 940 if (strm->avail_out == 0) { 941 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 942 return Z_OK; 943 } 944 } 945 } 946 Assert(strm->avail_out > 0, "bug2"); 947 948 if (flush != Z_FINISH) return Z_OK; 949 if (s->wrap <= 0) return Z_STREAM_END; 950 951 /* Write the trailer */ 952#ifdef GZIP 953 if (s->wrap == 2) { 954 put_byte(s, (Byte)(strm->adler & 0xff)); 955 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 956 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 957 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 958 put_byte(s, (Byte)(strm->total_in & 0xff)); 959 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 960 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 961 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 962 } 963 else 964#endif 965 { 966 putShortMSB(s, (uInt)(strm->adler >> 16)); 967 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 968 } 969 flush_pending(strm); 970 /* If avail_out is zero, the application will call deflate again 971 * to flush the rest. 972 */ 973 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 974 return s->pending != 0 ? Z_OK : Z_STREAM_END; 975} 976 977/* ========================================================================= */ 978int ZEXPORT deflateEnd ( 979 z_streamp strm) 980{ 981 int status; 982 983 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 984 985 status = strm->state->status; 986 if (status != INIT_STATE && 987 status != EXTRA_STATE && 988 status != NAME_STATE && 989 status != COMMENT_STATE && 990 status != HCRC_STATE && 991 status != BUSY_STATE && 992 status != FINISH_STATE) { 993 return Z_STREAM_ERROR; 994 } 995 996 /* Deallocate in reverse order of allocations: */ 997 TRY_FREE(strm, strm->state->pending_buf); 998 TRY_FREE(strm, strm->state->head); 999 TRY_FREE(strm, strm->state->prev); 1000 TRY_FREE(strm, strm->state->window); 1001 1002 ZFREE(strm, strm->state); 1003 strm->state = Z_NULL; 1004 1005 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1006} 1007 1008/* ========================================================================= 1009 * Copy the source state to the destination state. 1010 * To simplify the source, this is not supported for 16-bit MSDOS (which 1011 * doesn't have enough memory anyway to duplicate compression states). 1012 */ 1013int ZEXPORT deflateCopy ( 1014 z_streamp dest, 1015 z_streamp source) 1016{ 1017#ifdef MAXSEG_64K 1018 return Z_STREAM_ERROR; 1019#else 1020 deflate_state *ds; 1021 deflate_state *ss; 1022 ushf *overlay; 1023 1024 1025 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) { 1026 return Z_STREAM_ERROR; 1027 } 1028 1029 ss = source->state; 1030 1031 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream)); 1032 1033 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1034 if (ds == Z_NULL) return Z_MEM_ERROR; 1035 dest->state = (struct internal_state FAR *) ds; 1036 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state)); 1037 ds->strm = dest; 1038 1039 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1040 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1041 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1042 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); 1043 ds->pending_buf = (uchf *) overlay; 1044 1045 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1046 ds->pending_buf == Z_NULL) { 1047 deflateEnd (dest); 1048 return Z_MEM_ERROR; 1049 } 1050 /* following zmemcpy do not work for 16-bit MSDOS */ 1051 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1052 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos)); 1053 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos)); 1054 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); 1055 1056 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1057 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); 1058 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; 1059 1060 ds->l_desc.dyn_tree = ds->dyn_ltree; 1061 ds->d_desc.dyn_tree = ds->dyn_dtree; 1062 ds->bl_desc.dyn_tree = ds->bl_tree; 1063 1064 return Z_OK; 1065#endif /* MAXSEG_64K */ 1066} 1067 1068/* =========================================================================== 1069 * Read a new buffer from the current input stream, update the adler32 1070 * and total number of bytes read. All deflate() input goes through 1071 * this function so some applications may wish to modify it to avoid 1072 * allocating a large strm->next_in buffer and copying from it. 1073 * (See also flush_pending()). 1074 */ 1075local int read_buf( 1076 z_streamp strm, 1077 Bytef *buf, 1078 unsigned size) 1079{ 1080 unsigned len = strm->avail_in; 1081 1082 if (len > size) len = size; 1083 if (len == 0) return 0; 1084 1085 strm->avail_in -= len; 1086 1087 zmemcpy(buf, strm->next_in, len); 1088 if (strm->state->wrap == 1) { 1089 strm->adler = adler32(strm->adler, buf, len); 1090 } 1091#ifdef GZIP 1092 else if (strm->state->wrap == 2) { 1093 strm->adler = crc32(strm->adler, buf, len); 1094 } 1095#endif 1096 strm->next_in += len; 1097 strm->total_in += len; 1098 1099 return (int)len; 1100} 1101 1102/* =========================================================================== 1103 * Initialize the "longest match" routines for a new zlib stream 1104 */ 1105local void lm_init ( 1106 deflate_state *s) 1107{ 1108 s->window_size = (ulg)2L*s->w_size; 1109 1110 CLEAR_HASH(s); 1111 1112 /* Set the default configuration parameters: 1113 */ 1114 s->max_lazy_match = configuration_table[s->level].max_lazy; 1115 s->good_match = configuration_table[s->level].good_length; 1116 s->nice_match = configuration_table[s->level].nice_length; 1117 s->max_chain_length = configuration_table[s->level].max_chain; 1118 1119 s->strstart = 0; 1120 s->block_start = 0L; 1121 s->lookahead = 0; 1122 s->insert = 0; 1123 s->match_length = s->prev_length = MIN_MATCH-1; 1124 s->match_available = 0; 1125 s->ins_h = 0; 1126#ifndef FASTEST 1127#ifdef ASMV 1128 match_init(); /* initialize the asm code */ 1129#endif 1130#endif 1131} 1132 1133#ifndef FASTEST 1134/* =========================================================================== 1135 * Set match_start to the longest match starting at the given string and 1136 * return its length. Matches shorter or equal to prev_length are discarded, 1137 * in which case the result is equal to prev_length and match_start is 1138 * garbage. 1139 * IN assertions: cur_match is the head of the hash chain for the current 1140 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1141 * OUT assertion: the match length is not greater than s->lookahead. 1142 */ 1143#ifndef ASMV 1144/* For 80x86 and 680x0, an optimized version will be provided in match.asm or 1145 * match.S. The code will be functionally equivalent. 1146 */ 1147local uInt longest_match( 1148 deflate_state *s, 1149 IPos cur_match) /* current match */ 1150{ 1151 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1152 register Bytef *scan = s->window + s->strstart; /* current string */ 1153 register Bytef *match; /* matched string */ 1154 register int len; /* length of current match */ 1155 int best_len = s->prev_length; /* best match length so far */ 1156 int nice_match = s->nice_match; /* stop if match long enough */ 1157 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1158 s->strstart - (IPos)MAX_DIST(s) : NIL; 1159 /* Stop when cur_match becomes <= limit. To simplify the code, 1160 * we prevent matches with the string of window index 0. 1161 */ 1162 Posf *prev = s->prev; 1163 uInt wmask = s->w_mask; 1164 1165#ifdef UNALIGNED_OK 1166 /* Compare two bytes at a time. Note: this is not always beneficial. 1167 * Try with and without -DUNALIGNED_OK to check. 1168 */ 1169 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1170 register ush scan_start = *(ushf*)scan; 1171 register ush scan_end = *(ushf*)(scan+best_len-1); 1172#else 1173 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1174 register Byte scan_end1 = scan[best_len-1]; 1175 register Byte scan_end = scan[best_len]; 1176#endif 1177 1178 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1179 * It is easy to get rid of this optimization if necessary. 1180 */ 1181 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1182 1183 /* Do not waste too much time if we already have a good match: */ 1184 if (s->prev_length >= s->good_match) { 1185 chain_length >>= 2; 1186 } 1187 /* Do not look for matches beyond the end of the input. This is necessary 1188 * to make deflate deterministic. 1189 */ 1190 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; 1191 1192 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1193 1194 do { 1195 Assert(cur_match < s->strstart, "no future"); 1196 match = s->window + cur_match; 1197 1198 /* Skip to next match if the match length cannot increase 1199 * or if the match length is less than 2. Note that the checks below 1200 * for insufficient lookahead only occur occasionally for performance 1201 * reasons. Therefore uninitialized memory will be accessed, and 1202 * conditional jumps will be made that depend on those values. 1203 * However the length of the match is limited to the lookahead, so 1204 * the output of deflate is not affected by the uninitialized values. 1205 */ 1206#if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1207 /* This code assumes sizeof(unsigned short) == 2. Do not use 1208 * UNALIGNED_OK if your compiler uses a different size. 1209 */ 1210 if (*(ushf*)(match+best_len-1) != scan_end || 1211 *(ushf*)match != scan_start) continue; 1212 1213 /* It is not necessary to compare scan[2] and match[2] since they are 1214 * always equal when the other bytes match, given that the hash keys 1215 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1216 * strstart+3, +5, ... up to strstart+257. We check for insufficient 1217 * lookahead only every 4th comparison; the 128th check will be made 1218 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is 1219 * necessary to put more guard bytes at the end of the window, or 1220 * to check more often for insufficient lookahead. 1221 */ 1222 Assert(scan[2] == match[2], "scan[2]?"); 1223 scan++, match++; 1224 do { 1225 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1226 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1227 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1228 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1229 scan < strend); 1230 /* The funny "do {}" generates better code on most compilers */ 1231 1232 /* Here, scan <= window+strstart+257 */ 1233 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1234 if (*scan == *match) scan++; 1235 1236 len = (MAX_MATCH - 1) - (int)(strend-scan); 1237 scan = strend - (MAX_MATCH-1); 1238 1239#else /* UNALIGNED_OK */ 1240 1241 if (match[best_len] != scan_end || 1242 match[best_len-1] != scan_end1 || 1243 *match != *scan || 1244 *++match != scan[1]) continue; 1245 1246 /* The check at best_len-1 can be removed because it will be made 1247 * again later. (This heuristic is not always a win.) 1248 * It is not necessary to compare scan[2] and match[2] since they 1249 * are always equal when the other bytes match, given that 1250 * the hash keys are equal and that HASH_BITS >= 8. 1251 */ 1252 scan += 2, match++; 1253 Assert(*scan == *match, "match[2]?"); 1254 1255 /* We check for insufficient lookahead only every 8th comparison; 1256 * the 256th check will be made at strstart+258. 1257 */ 1258 do { 1259 } while (*++scan == *++match && *++scan == *++match && 1260 *++scan == *++match && *++scan == *++match && 1261 *++scan == *++match && *++scan == *++match && 1262 *++scan == *++match && *++scan == *++match && 1263 scan < strend); 1264 1265 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1266 1267 len = MAX_MATCH - (int)(strend - scan); 1268 scan = strend - MAX_MATCH; 1269 1270#endif /* UNALIGNED_OK */ 1271 1272 if (len > best_len) { 1273 s->match_start = cur_match; 1274 best_len = len; 1275 if (len >= nice_match) break; 1276#ifdef UNALIGNED_OK 1277 scan_end = *(ushf*)(scan+best_len-1); 1278#else 1279 scan_end1 = scan[best_len-1]; 1280 scan_end = scan[best_len]; 1281#endif 1282 } 1283 } while ((cur_match = prev[cur_match & wmask]) > limit 1284 && --chain_length != 0); 1285 1286 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1287 return s->lookahead; 1288} 1289#endif /* ASMV */ 1290 1291#else /* FASTEST */ 1292 1293/* --------------------------------------------------------------------------- 1294 * Optimized version for FASTEST only 1295 */ 1296local uInt longest_match( 1297 deflate_state *s, 1298 IPos cur_match) /* current match */ 1299{ 1300 register Bytef *scan = s->window + s->strstart; /* current string */ 1301 register Bytef *match; /* matched string */ 1302 register int len; /* length of current match */ 1303 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1304 1305 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1306 * It is easy to get rid of this optimization if necessary. 1307 */ 1308 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1309 1310 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1311 1312 Assert(cur_match < s->strstart, "no future"); 1313 1314 match = s->window + cur_match; 1315 1316 /* Return failure if the match length is less than 2: 1317 */ 1318 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1319 1320 /* The check at best_len-1 can be removed because it will be made 1321 * again later. (This heuristic is not always a win.) 1322 * It is not necessary to compare scan[2] and match[2] since they 1323 * are always equal when the other bytes match, given that 1324 * the hash keys are equal and that HASH_BITS >= 8. 1325 */ 1326 scan += 2, match += 2; 1327 Assert(*scan == *match, "match[2]?"); 1328 1329 /* We check for insufficient lookahead only every 8th comparison; 1330 * the 256th check will be made at strstart+258. 1331 */ 1332 do { 1333 } while (*++scan == *++match && *++scan == *++match && 1334 *++scan == *++match && *++scan == *++match && 1335 *++scan == *++match && *++scan == *++match && 1336 *++scan == *++match && *++scan == *++match && 1337 scan < strend); 1338 1339 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1340 1341 len = MAX_MATCH - (int)(strend - scan); 1342 1343 if (len < MIN_MATCH) return MIN_MATCH - 1; 1344 1345 s->match_start = cur_match; 1346 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1347} 1348 1349#endif /* FASTEST */ 1350 1351#ifdef DEBUG 1352/* =========================================================================== 1353 * Check that the match at match_start is indeed a match. 1354 */ 1355local void check_match( 1356 deflate_state *s, 1357 IPos start, IPos match, 1358 int length) 1359{ 1360 /* check that the match is indeed a match */ 1361 if (zmemcmp(s->window + match, 1362 s->window + start, length) != EQUAL) { 1363 fprintf(stderr, " start %u, match %u, length %d\n", 1364 start, match, length); 1365 do { 1366 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); 1367 } while (--length != 0); 1368 z_error("invalid match"); 1369 } 1370 if (z_verbose > 1) { 1371 fprintf(stderr,"\\[%d,%d]", start-match, length); 1372 do { putc(s->window[start++], stderr); } while (--length != 0); 1373 } 1374} 1375#else 1376# define check_match(s, start, match, length) 1377#endif /* DEBUG */ 1378 1379/* =========================================================================== 1380 * Fill the window when the lookahead becomes insufficient. 1381 * Updates strstart and lookahead. 1382 * 1383 * IN assertion: lookahead < MIN_LOOKAHEAD 1384 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 1385 * At least one byte has been read, or avail_in == 0; reads are 1386 * performed for at least two bytes (required for the zip translate_eol 1387 * option -- not supported here). 1388 */ 1389local void fill_window( 1390 deflate_state *s) 1391{ 1392 register unsigned n, m; 1393 register Posf *p; 1394 unsigned more; /* Amount of free space at the end of the window. */ 1395 uInt wsize = s->w_size; 1396 1397 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); 1398 1399 do { 1400 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 1401 1402 /* Deal with !@#$% 64K limit: */ 1403 if (sizeof(int) <= 2) { 1404 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 1405 more = wsize; 1406 1407 } else if (more == (unsigned)(-1)) { 1408 /* Very unlikely, but possible on 16 bit machine if 1409 * strstart == 0 && lookahead == 1 (input done a byte at time) 1410 */ 1411 more--; 1412 } 1413 } 1414 1415 /* If the window is almost full and there is insufficient lookahead, 1416 * move the upper half to the lower one to make room in the upper half. 1417 */ 1418 if (s->strstart >= wsize+MAX_DIST(s)) { 1419 1420 zmemcpy(s->window, s->window+wsize, (unsigned)wsize); 1421 s->match_start -= wsize; 1422 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 1423 s->block_start -= (long) wsize; 1424 1425 /* Slide the hash table (could be avoided with 32 bit values 1426 at the expense of memory usage). We slide even when level == 0 1427 to keep the hash table consistent if we switch back to level > 0 1428 later. (Using level 0 permanently is not an optimal usage of 1429 zlib, so we don't care about this pathological case.) 1430 */ 1431 n = s->hash_size; 1432 p = &s->head[n]; 1433 do { 1434 m = *--p; 1435 *p = (Pos)(m >= wsize ? m-wsize : NIL); 1436 } while (--n); 1437 1438 n = wsize; 1439#ifndef FASTEST 1440 p = &s->prev[n]; 1441 do { 1442 m = *--p; 1443 *p = (Pos)(m >= wsize ? m-wsize : NIL); 1444 /* If n is not on any hash chain, prev[n] is garbage but 1445 * its value will never be used. 1446 */ 1447 } while (--n); 1448#endif 1449 more += wsize; 1450 } 1451 if (s->strm->avail_in == 0) break; 1452 1453 /* If there was no sliding: 1454 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 1455 * more == window_size - lookahead - strstart 1456 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 1457 * => more >= window_size - 2*WSIZE + 2 1458 * In the BIG_MEM or MMAP case (not yet supported), 1459 * window_size == input_size + MIN_LOOKAHEAD && 1460 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 1461 * Otherwise, window_size == 2*WSIZE so more >= 2. 1462 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 1463 */ 1464 Assert(more >= 2, "more < 2"); 1465 1466 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 1467 s->lookahead += n; 1468 1469 /* Initialize the hash value now that we have some input: */ 1470 if (s->lookahead + s->insert >= MIN_MATCH) { 1471 uInt str = s->strstart - s->insert; 1472 s->ins_h = s->window[str]; 1473 UPDATE_HASH(s, s->ins_h, s->window[str + 1]); 1474#if MIN_MATCH != 3 1475 Call UPDATE_HASH() MIN_MATCH-3 more times 1476#endif 1477 while (s->insert) { 1478 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 1479#ifndef FASTEST 1480 s->prev[str & s->w_mask] = s->head[s->ins_h]; 1481#endif 1482 s->head[s->ins_h] = (Pos)str; 1483 str++; 1484 s->insert--; 1485 if (s->lookahead + s->insert < MIN_MATCH) 1486 break; 1487 } 1488 } 1489 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 1490 * but this is not important since only literal bytes will be emitted. 1491 */ 1492 1493 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 1494 1495 /* If the WIN_INIT bytes after the end of the current data have never been 1496 * written, then zero those bytes in order to avoid memory check reports of 1497 * the use of uninitialized (or uninitialised as Julian writes) bytes by 1498 * the longest match routines. Update the high water mark for the next 1499 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 1500 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 1501 */ 1502 if (s->high_water < s->window_size) { 1503 ulg curr = s->strstart + (ulg)(s->lookahead); 1504 ulg init; 1505 1506 if (s->high_water < curr) { 1507 /* Previous high water mark below current data -- zero WIN_INIT 1508 * bytes or up to end of window, whichever is less. 1509 */ 1510 init = s->window_size - curr; 1511 if (init > WIN_INIT) 1512 init = WIN_INIT; 1513 zmemzero(s->window + curr, (unsigned)init); 1514 s->high_water = curr + init; 1515 } 1516 else if (s->high_water < (ulg)curr + WIN_INIT) { 1517 /* High water mark at or above current data, but below current data 1518 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 1519 * to end of window, whichever is less. 1520 */ 1521 init = (ulg)curr + WIN_INIT - s->high_water; 1522 if (init > s->window_size - s->high_water) 1523 init = s->window_size - s->high_water; 1524 zmemzero(s->window + s->high_water, (unsigned)init); 1525 s->high_water += init; 1526 } 1527 } 1528 1529 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1530 "not enough room for search"); 1531} 1532 1533/* =========================================================================== 1534 * Flush the current block, with given end-of-file flag. 1535 * IN assertion: strstart is set to the end of the current match. 1536 */ 1537#define FLUSH_BLOCK_ONLY(s, last) { \ 1538 _tr_flush_block(s, (s->block_start >= 0L ? \ 1539 (charf *)&s->window[(unsigned)s->block_start] : \ 1540 (charf *)Z_NULL), \ 1541 (ulg)((long)s->strstart - s->block_start), \ 1542 (last)); \ 1543 s->block_start = s->strstart; \ 1544 flush_pending(s->strm); \ 1545 Tracev((stderr,"[FLUSH]")); \ 1546} 1547 1548/* Same but force premature exit if necessary. */ 1549#define FLUSH_BLOCK(s, last) { \ 1550 FLUSH_BLOCK_ONLY(s, last); \ 1551 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1552} 1553 1554/* =========================================================================== 1555 * Copy without compression as much as possible from the input stream, return 1556 * the current block state. 1557 * This function does not insert new strings in the dictionary since 1558 * uncompressible data is probably not useful. This function is used 1559 * only for the level=0 compression option. 1560 * NOTE: this function should be optimized to avoid extra copying from 1561 * window to pending_buf. 1562 */ 1563local block_state deflate_stored( 1564 deflate_state *s, 1565 int flush) 1566{ 1567 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited 1568 * to pending_buf_size, and each stored block has a 5 byte header: 1569 */ 1570 ulg max_block_size = 0xffff; 1571 ulg max_start; 1572 1573 if (max_block_size > s->pending_buf_size - 5) { 1574 max_block_size = s->pending_buf_size - 5; 1575 } 1576 1577 /* Copy as much as possible from input to output: */ 1578 for (;;) { 1579 /* Fill the window as much as possible: */ 1580 if (s->lookahead <= 1) { 1581 1582 Assert(s->strstart < s->w_size+MAX_DIST(s) || 1583 s->block_start >= (long)s->w_size, "slide too late"); 1584 1585 fill_window(s); 1586 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more; 1587 1588 if (s->lookahead == 0) break; /* flush the current block */ 1589 } 1590 Assert(s->block_start >= 0L, "block gone"); 1591 1592 s->strstart += s->lookahead; 1593 s->lookahead = 0; 1594 1595 /* Emit a stored block if pending_buf will be full: */ 1596 max_start = s->block_start + max_block_size; 1597 if (s->strstart == 0 || (ulg)s->strstart >= max_start) { 1598 /* strstart == 0 is possible when wraparound on 16-bit machine */ 1599 s->lookahead = (uInt)(s->strstart - max_start); 1600 s->strstart = (uInt)max_start; 1601 FLUSH_BLOCK(s, 0); 1602 } 1603 /* Flush if we may have to slide, otherwise block_start may become 1604 * negative and the data will be gone: 1605 */ 1606 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) { 1607 FLUSH_BLOCK(s, 0); 1608 } 1609 } 1610 s->insert = 0; 1611 if (flush == Z_FINISH) { 1612 FLUSH_BLOCK(s, 1); 1613 return finish_done; 1614 } 1615 if ((long)s->strstart > s->block_start) 1616 FLUSH_BLOCK(s, 0); 1617 return block_done; 1618} 1619 1620/* =========================================================================== 1621 * Compress as much as possible from the input stream, return the current 1622 * block state. 1623 * This function does not perform lazy evaluation of matches and inserts 1624 * new strings in the dictionary only for unmatched strings or for short 1625 * matches. It is used only for the fast compression options. 1626 */ 1627local block_state deflate_fast( 1628 deflate_state *s, 1629 int flush) 1630{ 1631 IPos hash_head; /* head of the hash chain */ 1632 int bflush; /* set if current block must be flushed */ 1633 1634 for (;;) { 1635 /* Make sure that we always have enough lookahead, except 1636 * at the end of the input file. We need MAX_MATCH bytes 1637 * for the next match, plus MIN_MATCH bytes to insert the 1638 * string following the next match. 1639 */ 1640 if (s->lookahead < MIN_LOOKAHEAD) { 1641 fill_window(s); 1642 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1643 return need_more; 1644 } 1645 if (s->lookahead == 0) break; /* flush the current block */ 1646 } 1647 1648 /* Insert the string window[strstart .. strstart+2] in the 1649 * dictionary, and set hash_head to the head of the hash chain: 1650 */ 1651 hash_head = NIL; 1652 if (s->lookahead >= MIN_MATCH) { 1653 INSERT_STRING(s, s->strstart, hash_head); 1654 } 1655 1656 /* Find the longest match, discarding those <= prev_length. 1657 * At this point we have always match_length < MIN_MATCH 1658 */ 1659 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1660 /* To simplify the code, we prevent matches with the string 1661 * of window index 0 (in particular we have to avoid a match 1662 * of the string with itself at the start of the input file). 1663 */ 1664 s->match_length = longest_match (s, hash_head); 1665 /* longest_match() sets match_start */ 1666 } 1667 if (s->match_length >= MIN_MATCH) { 1668 check_match(s, s->strstart, s->match_start, s->match_length); 1669 1670 _tr_tally_dist(s, s->strstart - s->match_start, 1671 s->match_length - MIN_MATCH, bflush); 1672 1673 s->lookahead -= s->match_length; 1674 1675 /* Insert new strings in the hash table only if the match length 1676 * is not too large. This saves time but degrades compression. 1677 */ 1678#ifndef FASTEST 1679 if (s->match_length <= s->max_insert_length && 1680 s->lookahead >= MIN_MATCH) { 1681 s->match_length--; /* string at strstart already in table */ 1682 do { 1683 s->strstart++; 1684 INSERT_STRING(s, s->strstart, hash_head); 1685 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1686 * always MIN_MATCH bytes ahead. 1687 */ 1688 } while (--s->match_length != 0); 1689 s->strstart++; 1690 } else 1691#endif 1692 { 1693 s->strstart += s->match_length; 1694 s->match_length = 0; 1695 s->ins_h = s->window[s->strstart]; 1696 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); 1697#if MIN_MATCH != 3 1698 Call UPDATE_HASH() MIN_MATCH-3 more times 1699#endif 1700 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1701 * matter since it will be recomputed at next deflate call. 1702 */ 1703 } 1704 } else { 1705 /* No match, output a literal byte */ 1706 Tracevv((stderr,"%c", s->window[s->strstart])); 1707 _tr_tally_lit (s, s->window[s->strstart], bflush); 1708 s->lookahead--; 1709 s->strstart++; 1710 } 1711 if (bflush) FLUSH_BLOCK(s, 0); 1712 } 1713 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1714 if (flush == Z_FINISH) { 1715 FLUSH_BLOCK(s, 1); 1716 return finish_done; 1717 } 1718 if (s->last_lit) 1719 FLUSH_BLOCK(s, 0); 1720 return block_done; 1721} 1722 1723#ifndef FASTEST 1724/* =========================================================================== 1725 * Same as above, but achieves better compression. We use a lazy 1726 * evaluation for matches: a match is finally adopted only if there is 1727 * no better match at the next window position. 1728 */ 1729local block_state deflate_slow( 1730 deflate_state *s, 1731 int flush) 1732{ 1733 IPos hash_head; /* head of hash chain */ 1734 int bflush; /* set if current block must be flushed */ 1735 1736 /* Process the input block. */ 1737 for (;;) { 1738 /* Make sure that we always have enough lookahead, except 1739 * at the end of the input file. We need MAX_MATCH bytes 1740 * for the next match, plus MIN_MATCH bytes to insert the 1741 * string following the next match. 1742 */ 1743 if (s->lookahead < MIN_LOOKAHEAD) { 1744 fill_window(s); 1745 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1746 return need_more; 1747 } 1748 if (s->lookahead == 0) break; /* flush the current block */ 1749 } 1750 1751 /* Insert the string window[strstart .. strstart+2] in the 1752 * dictionary, and set hash_head to the head of the hash chain: 1753 */ 1754 hash_head = NIL; 1755 if (s->lookahead >= MIN_MATCH) { 1756 INSERT_STRING(s, s->strstart, hash_head); 1757 } 1758 1759 /* Find the longest match, discarding those <= prev_length. 1760 */ 1761 s->prev_length = s->match_length, s->prev_match = s->match_start; 1762 s->match_length = MIN_MATCH-1; 1763 1764 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1765 s->strstart - hash_head <= MAX_DIST(s)) { 1766 /* To simplify the code, we prevent matches with the string 1767 * of window index 0 (in particular we have to avoid a match 1768 * of the string with itself at the start of the input file). 1769 */ 1770 s->match_length = longest_match (s, hash_head); 1771 /* longest_match() sets match_start */ 1772 1773 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1774#if TOO_FAR <= 32767 1775 || (s->match_length == MIN_MATCH && 1776 s->strstart - s->match_start > TOO_FAR) 1777#endif 1778 )) { 1779 1780 /* If prev_match is also MIN_MATCH, match_start is garbage 1781 * but we will ignore the current match anyway. 1782 */ 1783 s->match_length = MIN_MATCH-1; 1784 } 1785 } 1786 /* If there was a match at the previous step and the current 1787 * match is not better, output the previous match: 1788 */ 1789 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1790 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1791 /* Do not insert strings in hash table beyond this. */ 1792 1793 check_match(s, s->strstart-1, s->prev_match, s->prev_length); 1794 1795 _tr_tally_dist(s, s->strstart -1 - s->prev_match, 1796 s->prev_length - MIN_MATCH, bflush); 1797 1798 /* Insert in hash table all strings up to the end of the match. 1799 * strstart-1 and strstart are already inserted. If there is not 1800 * enough lookahead, the last two strings are not inserted in 1801 * the hash table. 1802 */ 1803 s->lookahead -= s->prev_length-1; 1804 s->prev_length -= 2; 1805 do { 1806 if (++s->strstart <= max_insert) { 1807 INSERT_STRING(s, s->strstart, hash_head); 1808 } 1809 } while (--s->prev_length != 0); 1810 s->match_available = 0; 1811 s->match_length = MIN_MATCH-1; 1812 s->strstart++; 1813 1814 if (bflush) FLUSH_BLOCK(s, 0); 1815 1816 } else if (s->match_available) { 1817 /* If there was no match at the previous position, output a 1818 * single literal. If there was a match but the current match 1819 * is longer, truncate the previous match to a single literal. 1820 */ 1821 Tracevv((stderr,"%c", s->window[s->strstart-1])); 1822 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 1823 if (bflush) { 1824 FLUSH_BLOCK_ONLY(s, 0); 1825 } 1826 s->strstart++; 1827 s->lookahead--; 1828 if (s->strm->avail_out == 0) return need_more; 1829 } else { 1830 /* There is no previous match to compare with, wait for 1831 * the next step to decide. 1832 */ 1833 s->match_available = 1; 1834 s->strstart++; 1835 s->lookahead--; 1836 } 1837 } 1838 Assert (flush != Z_NO_FLUSH, "no flush?"); 1839 if (s->match_available) { 1840 Tracevv((stderr,"%c", s->window[s->strstart-1])); 1841 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 1842 s->match_available = 0; 1843 } 1844 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1845 if (flush == Z_FINISH) { 1846 FLUSH_BLOCK(s, 1); 1847 return finish_done; 1848 } 1849 if (s->last_lit) 1850 FLUSH_BLOCK(s, 0); 1851 return block_done; 1852} 1853#endif /* FASTEST */ 1854 1855/* =========================================================================== 1856 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 1857 * one. Do not maintain a hash table. (It will be regenerated if this run of 1858 * deflate switches away from Z_RLE.) 1859 */ 1860local block_state deflate_rle( 1861 deflate_state *s, 1862 int flush) 1863{ 1864 int bflush; /* set if current block must be flushed */ 1865 uInt prev; /* byte at distance one to match */ 1866 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 1867 1868 for (;;) { 1869 /* Make sure that we always have enough lookahead, except 1870 * at the end of the input file. We need MAX_MATCH bytes 1871 * for the longest run, plus one for the unrolled loop. 1872 */ 1873 if (s->lookahead <= MAX_MATCH) { 1874 fill_window(s); 1875 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 1876 return need_more; 1877 } 1878 if (s->lookahead == 0) break; /* flush the current block */ 1879 } 1880 1881 /* See how many times the previous byte repeats */ 1882 s->match_length = 0; 1883 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 1884 scan = s->window + s->strstart - 1; 1885 prev = *scan; 1886 if (prev == *++scan && prev == *++scan && prev == *++scan) { 1887 strend = s->window + s->strstart + MAX_MATCH; 1888 do { 1889 } while (prev == *++scan && prev == *++scan && 1890 prev == *++scan && prev == *++scan && 1891 prev == *++scan && prev == *++scan && 1892 prev == *++scan && prev == *++scan && 1893 scan < strend); 1894 s->match_length = MAX_MATCH - (int)(strend - scan); 1895 if (s->match_length > s->lookahead) 1896 s->match_length = s->lookahead; 1897 } 1898 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan"); 1899 } 1900 1901 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 1902 if (s->match_length >= MIN_MATCH) { 1903 check_match(s, s->strstart, s->strstart - 1, s->match_length); 1904 1905 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 1906 1907 s->lookahead -= s->match_length; 1908 s->strstart += s->match_length; 1909 s->match_length = 0; 1910 } else { 1911 /* No match, output a literal byte */ 1912 Tracevv((stderr,"%c", s->window[s->strstart])); 1913 _tr_tally_lit (s, s->window[s->strstart], bflush); 1914 s->lookahead--; 1915 s->strstart++; 1916 } 1917 if (bflush) FLUSH_BLOCK(s, 0); 1918 } 1919 s->insert = 0; 1920 if (flush == Z_FINISH) { 1921 FLUSH_BLOCK(s, 1); 1922 return finish_done; 1923 } 1924 if (s->last_lit) 1925 FLUSH_BLOCK(s, 0); 1926 return block_done; 1927} 1928 1929/* =========================================================================== 1930 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 1931 * (It will be regenerated if this run of deflate switches away from Huffman.) 1932 */ 1933local block_state deflate_huff( 1934 deflate_state *s, 1935 int flush) 1936{ 1937 int bflush; /* set if current block must be flushed */ 1938 1939 for (;;) { 1940 /* Make sure that we have a literal to write. */ 1941 if (s->lookahead == 0) { 1942 fill_window(s); 1943 if (s->lookahead == 0) { 1944 if (flush == Z_NO_FLUSH) 1945 return need_more; 1946 break; /* flush the current block */ 1947 } 1948 } 1949 1950 /* Output a literal byte */ 1951 s->match_length = 0; 1952 Tracevv((stderr,"%c", s->window[s->strstart])); 1953 _tr_tally_lit (s, s->window[s->strstart], bflush); 1954 s->lookahead--; 1955 s->strstart++; 1956 if (bflush) FLUSH_BLOCK(s, 0); 1957 } 1958 s->insert = 0; 1959 if (flush == Z_FINISH) { 1960 FLUSH_BLOCK(s, 1); 1961 return finish_done; 1962 } 1963 if (s->last_lit) 1964 FLUSH_BLOCK(s, 0); 1965 return block_done; 1966} 1967