deflate.c revision 09eb358bbbb9aad3fe48dd3368c8a7a481cbda1c
1/* deflate.c -- compress data using the deflation algorithm 2 * Copyright (C) 1995-2012 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 1.2.7 Copyright 1995-2012 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_(strm, level, version, stream_size) 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_(strm, level, method, windowBits, memLevel, strategy, 214 version, stream_size) 215 z_streamp strm; 216 int level; 217 int method; 218 int windowBits; 219 int memLevel; 220 int strategy; 221 const char *version; 222 int stream_size; 223{ 224 deflate_state *s; 225 int wrap = 1; 226 static const char my_version[] = ZLIB_VERSION; 227 228 ushf *overlay; 229 /* We overlay pending_buf and d_buf+l_buf. This works since the average 230 * output size for (length,distance) codes is <= 24 bits. 231 */ 232 233 if (version == Z_NULL || version[0] != my_version[0] || 234 stream_size != sizeof(z_stream)) { 235 return Z_VERSION_ERROR; 236 } 237 if (strm == Z_NULL) return Z_STREAM_ERROR; 238 239 strm->msg = Z_NULL; 240 if (strm->zalloc == (alloc_func)0) { 241#ifdef Z_SOLO 242 return Z_STREAM_ERROR; 243#else 244 strm->zalloc = zcalloc; 245 strm->opaque = (voidpf)0; 246#endif 247 } 248 if (strm->zfree == (free_func)0) 249#ifdef Z_SOLO 250 return Z_STREAM_ERROR; 251#else 252 strm->zfree = zcfree; 253#endif 254 255#ifdef FASTEST 256 if (level != 0) level = 1; 257#else 258 if (level == Z_DEFAULT_COMPRESSION) level = 6; 259#endif 260 261 if (windowBits < 0) { /* suppress zlib wrapper */ 262 wrap = 0; 263 windowBits = -windowBits; 264 } 265#ifdef GZIP 266 else if (windowBits > 15) { 267 wrap = 2; /* write gzip wrapper instead */ 268 windowBits -= 16; 269 } 270#endif 271 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 272 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 273 strategy < 0 || strategy > Z_FIXED) { 274 return Z_STREAM_ERROR; 275 } 276 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 277 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 278 if (s == Z_NULL) return Z_MEM_ERROR; 279 strm->state = (struct internal_state FAR *)s; 280 s->strm = strm; 281 282 s->wrap = wrap; 283 s->gzhead = Z_NULL; 284 s->w_bits = windowBits; 285 s->w_size = 1 << s->w_bits; 286 s->w_mask = s->w_size - 1; 287 288 s->hash_bits = memLevel + 7; 289 s->hash_size = 1 << s->hash_bits; 290 s->hash_mask = s->hash_size - 1; 291 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); 292 293 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 294 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 295 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 296 297 s->high_water = 0; /* nothing written to s->window yet */ 298 299 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 300 301 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); 302 s->pending_buf = (uchf *) overlay; 303 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); 304 305 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 306 s->pending_buf == Z_NULL) { 307 s->status = FINISH_STATE; 308 strm->msg = (char*)ERR_MSG(Z_MEM_ERROR); 309 deflateEnd (strm); 310 return Z_MEM_ERROR; 311 } 312 s->d_buf = overlay + s->lit_bufsize/sizeof(ush); 313 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; 314 315 s->level = level; 316 s->strategy = strategy; 317 s->method = (Byte)method; 318 319 return deflateReset(strm); 320} 321 322/* ========================================================================= */ 323int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength) 324 z_streamp strm; 325 const Bytef *dictionary; 326 uInt dictLength; 327{ 328 deflate_state *s; 329 uInt str, n; 330 int wrap; 331 unsigned avail; 332 unsigned char *next; 333 334 if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL) 335 return Z_STREAM_ERROR; 336 s = strm->state; 337 wrap = s->wrap; 338 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) 339 return Z_STREAM_ERROR; 340 341 /* when using zlib wrappers, compute Adler-32 for provided dictionary */ 342 if (wrap == 1) 343 strm->adler = adler32(strm->adler, dictionary, dictLength); 344 s->wrap = 0; /* avoid computing Adler-32 in read_buf */ 345 346 /* if dictionary would fill window, just replace the history */ 347 if (dictLength >= s->w_size) { 348 if (wrap == 0) { /* already empty otherwise */ 349 CLEAR_HASH(s); 350 s->strstart = 0; 351 s->block_start = 0L; 352 s->insert = 0; 353 } 354 dictionary += dictLength - s->w_size; /* use the tail */ 355 dictLength = s->w_size; 356 } 357 358 /* insert dictionary into window and hash */ 359 avail = strm->avail_in; 360 next = strm->next_in; 361 strm->avail_in = dictLength; 362 strm->next_in = (Bytef *)dictionary; 363 fill_window(s); 364 while (s->lookahead >= MIN_MATCH) { 365 str = s->strstart; 366 n = s->lookahead - (MIN_MATCH-1); 367 do { 368 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 369#ifndef FASTEST 370 s->prev[str & s->w_mask] = s->head[s->ins_h]; 371#endif 372 s->head[s->ins_h] = (Pos)str; 373 str++; 374 } while (--n); 375 s->strstart = str; 376 s->lookahead = MIN_MATCH-1; 377 fill_window(s); 378 } 379 s->strstart += s->lookahead; 380 s->block_start = (long)s->strstart; 381 s->insert = s->lookahead; 382 s->lookahead = 0; 383 s->match_length = s->prev_length = MIN_MATCH-1; 384 s->match_available = 0; 385 strm->next_in = next; 386 strm->avail_in = avail; 387 s->wrap = wrap; 388 return Z_OK; 389} 390 391/* ========================================================================= */ 392int ZEXPORT deflateResetKeep (strm) 393 z_streamp strm; 394{ 395 deflate_state *s; 396 397 if (strm == Z_NULL || strm->state == Z_NULL || 398 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) { 399 return Z_STREAM_ERROR; 400 } 401 402 strm->total_in = strm->total_out = 0; 403 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 404 strm->data_type = Z_UNKNOWN; 405 406 s = (deflate_state *)strm->state; 407 s->pending = 0; 408 s->pending_out = s->pending_buf; 409 410 if (s->wrap < 0) { 411 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 412 } 413 s->status = s->wrap ? INIT_STATE : BUSY_STATE; 414 strm->adler = 415#ifdef GZIP 416 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 417#endif 418 adler32(0L, Z_NULL, 0); 419 s->last_flush = Z_NO_FLUSH; 420 421 _tr_init(s); 422 423 return Z_OK; 424} 425 426/* ========================================================================= */ 427int ZEXPORT deflateReset (strm) 428 z_streamp strm; 429{ 430 int ret; 431 432 ret = deflateResetKeep(strm); 433 if (ret == Z_OK) 434 lm_init(strm->state); 435 return ret; 436} 437 438/* ========================================================================= */ 439int ZEXPORT deflateSetHeader (strm, head) 440 z_streamp strm; 441 gz_headerp head; 442{ 443 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 444 if (strm->state->wrap != 2) return Z_STREAM_ERROR; 445 strm->state->gzhead = head; 446 return Z_OK; 447} 448 449/* ========================================================================= */ 450int ZEXPORT deflatePending (strm, pending, bits) 451 unsigned *pending; 452 int *bits; 453 z_streamp strm; 454{ 455 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 456 if (pending != Z_NULL) 457 *pending = strm->state->pending; 458 if (bits != Z_NULL) 459 *bits = strm->state->bi_valid; 460 return Z_OK; 461} 462 463/* ========================================================================= */ 464int ZEXPORT deflatePrime (strm, bits, value) 465 z_streamp strm; 466 int bits; 467 int value; 468{ 469 deflate_state *s; 470 int put; 471 472 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 473 s = strm->state; 474 if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3)) 475 return Z_BUF_ERROR; 476 do { 477 put = Buf_size - s->bi_valid; 478 if (put > bits) 479 put = bits; 480 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); 481 s->bi_valid += put; 482 _tr_flush_bits(s); 483 value >>= put; 484 bits -= put; 485 } while (bits); 486 return Z_OK; 487} 488 489/* ========================================================================= */ 490int ZEXPORT deflateParams(strm, level, strategy) 491 z_streamp strm; 492 int level; 493 int strategy; 494{ 495 deflate_state *s; 496 compress_func func; 497 int err = Z_OK; 498 499 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 500 s = strm->state; 501 502#ifdef FASTEST 503 if (level != 0) level = 1; 504#else 505 if (level == Z_DEFAULT_COMPRESSION) level = 6; 506#endif 507 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 508 return Z_STREAM_ERROR; 509 } 510 func = configuration_table[s->level].func; 511 512 if ((strategy != s->strategy || func != configuration_table[level].func) && 513 strm->total_in != 0) { 514 /* Flush the last buffer: */ 515 err = deflate(strm, Z_BLOCK); 516 } 517 if (s->level != level) { 518 s->level = level; 519 s->max_lazy_match = configuration_table[level].max_lazy; 520 s->good_match = configuration_table[level].good_length; 521 s->nice_match = configuration_table[level].nice_length; 522 s->max_chain_length = configuration_table[level].max_chain; 523 } 524 s->strategy = strategy; 525 return err; 526} 527 528/* ========================================================================= */ 529int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain) 530 z_streamp strm; 531 int good_length; 532 int max_lazy; 533 int nice_length; 534 int max_chain; 535{ 536 deflate_state *s; 537 538 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 539 s = strm->state; 540 s->good_match = good_length; 541 s->max_lazy_match = max_lazy; 542 s->nice_match = nice_length; 543 s->max_chain_length = max_chain; 544 return Z_OK; 545} 546 547/* ========================================================================= 548 * For the default windowBits of 15 and memLevel of 8, this function returns 549 * a close to exact, as well as small, upper bound on the compressed size. 550 * They are coded as constants here for a reason--if the #define's are 551 * changed, then this function needs to be changed as well. The return 552 * value for 15 and 8 only works for those exact settings. 553 * 554 * For any setting other than those defaults for windowBits and memLevel, 555 * the value returned is a conservative worst case for the maximum expansion 556 * resulting from using fixed blocks instead of stored blocks, which deflate 557 * can emit on compressed data for some combinations of the parameters. 558 * 559 * This function could be more sophisticated to provide closer upper bounds for 560 * every combination of windowBits and memLevel. But even the conservative 561 * upper bound of about 14% expansion does not seem onerous for output buffer 562 * allocation. 563 */ 564uLong ZEXPORT deflateBound(strm, sourceLen) 565 z_streamp strm; 566 uLong sourceLen; 567{ 568 deflate_state *s; 569 uLong complen, wraplen; 570 Bytef *str; 571 572 /* conservative upper bound for compressed data */ 573 complen = sourceLen + 574 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5; 575 576 /* if can't get parameters, return conservative bound plus zlib wrapper */ 577 if (strm == Z_NULL || strm->state == Z_NULL) 578 return complen + 6; 579 580 /* compute wrapper length */ 581 s = strm->state; 582 switch (s->wrap) { 583 case 0: /* raw deflate */ 584 wraplen = 0; 585 break; 586 case 1: /* zlib wrapper */ 587 wraplen = 6 + (s->strstart ? 4 : 0); 588 break; 589 case 2: /* gzip wrapper */ 590 wraplen = 18; 591 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 592 if (s->gzhead->extra != Z_NULL) 593 wraplen += 2 + s->gzhead->extra_len; 594 str = s->gzhead->name; 595 if (str != Z_NULL) 596 do { 597 wraplen++; 598 } while (*str++); 599 str = s->gzhead->comment; 600 if (str != Z_NULL) 601 do { 602 wraplen++; 603 } while (*str++); 604 if (s->gzhead->hcrc) 605 wraplen += 2; 606 } 607 break; 608 default: /* for compiler happiness */ 609 wraplen = 6; 610 } 611 612 /* if not default parameters, return conservative bound */ 613 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 614 return complen + wraplen; 615 616 /* default settings: return tight bound for that case */ 617 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 618 (sourceLen >> 25) + 13 - 6 + wraplen; 619} 620 621/* ========================================================================= 622 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 623 * IN assertion: the stream state is correct and there is enough room in 624 * pending_buf. 625 */ 626local void putShortMSB (s, b) 627 deflate_state *s; 628 uInt b; 629{ 630 put_byte(s, (Byte)(b >> 8)); 631 put_byte(s, (Byte)(b & 0xff)); 632} 633 634/* ========================================================================= 635 * Flush as much pending output as possible. All deflate() output goes 636 * through this function so some applications may wish to modify it 637 * to avoid allocating a large strm->next_out buffer and copying into it. 638 * (See also read_buf()). 639 */ 640local void flush_pending(strm) 641 z_streamp strm; 642{ 643 unsigned len; 644 deflate_state *s = strm->state; 645 646 _tr_flush_bits(s); 647 len = s->pending; 648 if (len > strm->avail_out) len = strm->avail_out; 649 if (len == 0) return; 650 651 zmemcpy(strm->next_out, s->pending_out, len); 652 strm->next_out += len; 653 s->pending_out += len; 654 strm->total_out += len; 655 strm->avail_out -= len; 656 s->pending -= len; 657 if (s->pending == 0) { 658 s->pending_out = s->pending_buf; 659 } 660} 661 662/* ========================================================================= */ 663int ZEXPORT deflate (strm, flush) 664 z_streamp strm; 665 int flush; 666{ 667 int old_flush; /* value of flush param for previous deflate call */ 668 deflate_state *s; 669 670 if (strm == Z_NULL || strm->state == Z_NULL || 671 flush > Z_BLOCK || flush < 0) { 672 return Z_STREAM_ERROR; 673 } 674 s = strm->state; 675 676 if (strm->next_out == Z_NULL || 677 (strm->next_in == Z_NULL && strm->avail_in != 0) || 678 (s->status == FINISH_STATE && flush != Z_FINISH)) { 679 ERR_RETURN(strm, Z_STREAM_ERROR); 680 } 681 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 682 683 s->strm = strm; /* just in case */ 684 old_flush = s->last_flush; 685 s->last_flush = flush; 686 687 /* Write the header */ 688 if (s->status == INIT_STATE) { 689#ifdef GZIP 690 if (s->wrap == 2) { 691 strm->adler = crc32(0L, Z_NULL, 0); 692 put_byte(s, 31); 693 put_byte(s, 139); 694 put_byte(s, 8); 695 if (s->gzhead == Z_NULL) { 696 put_byte(s, 0); 697 put_byte(s, 0); 698 put_byte(s, 0); 699 put_byte(s, 0); 700 put_byte(s, 0); 701 put_byte(s, s->level == 9 ? 2 : 702 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 703 4 : 0)); 704 put_byte(s, OS_CODE); 705 s->status = BUSY_STATE; 706 } 707 else { 708 put_byte(s, (s->gzhead->text ? 1 : 0) + 709 (s->gzhead->hcrc ? 2 : 0) + 710 (s->gzhead->extra == Z_NULL ? 0 : 4) + 711 (s->gzhead->name == Z_NULL ? 0 : 8) + 712 (s->gzhead->comment == Z_NULL ? 0 : 16) 713 ); 714 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 715 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 716 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 717 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 718 put_byte(s, s->level == 9 ? 2 : 719 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 720 4 : 0)); 721 put_byte(s, s->gzhead->os & 0xff); 722 if (s->gzhead->extra != Z_NULL) { 723 put_byte(s, s->gzhead->extra_len & 0xff); 724 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 725 } 726 if (s->gzhead->hcrc) 727 strm->adler = crc32(strm->adler, s->pending_buf, 728 s->pending); 729 s->gzindex = 0; 730 s->status = EXTRA_STATE; 731 } 732 } 733 else 734#endif 735 { 736 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; 737 uInt level_flags; 738 739 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 740 level_flags = 0; 741 else if (s->level < 6) 742 level_flags = 1; 743 else if (s->level == 6) 744 level_flags = 2; 745 else 746 level_flags = 3; 747 header |= (level_flags << 6); 748 if (s->strstart != 0) header |= PRESET_DICT; 749 header += 31 - (header % 31); 750 751 s->status = BUSY_STATE; 752 putShortMSB(s, header); 753 754 /* Save the adler32 of the preset dictionary: */ 755 if (s->strstart != 0) { 756 putShortMSB(s, (uInt)(strm->adler >> 16)); 757 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 758 } 759 strm->adler = adler32(0L, Z_NULL, 0); 760 } 761 } 762#ifdef GZIP 763 if (s->status == EXTRA_STATE) { 764 if (s->gzhead->extra != Z_NULL) { 765 uInt beg = s->pending; /* start of bytes to update crc */ 766 767 while (s->gzindex < (s->gzhead->extra_len & 0xffff)) { 768 if (s->pending == s->pending_buf_size) { 769 if (s->gzhead->hcrc && s->pending > beg) 770 strm->adler = crc32(strm->adler, s->pending_buf + beg, 771 s->pending - beg); 772 flush_pending(strm); 773 beg = s->pending; 774 if (s->pending == s->pending_buf_size) 775 break; 776 } 777 put_byte(s, s->gzhead->extra[s->gzindex]); 778 s->gzindex++; 779 } 780 if (s->gzhead->hcrc && s->pending > beg) 781 strm->adler = crc32(strm->adler, s->pending_buf + beg, 782 s->pending - beg); 783 if (s->gzindex == s->gzhead->extra_len) { 784 s->gzindex = 0; 785 s->status = NAME_STATE; 786 } 787 } 788 else 789 s->status = NAME_STATE; 790 } 791 if (s->status == NAME_STATE) { 792 if (s->gzhead->name != Z_NULL) { 793 uInt beg = s->pending; /* start of bytes to update crc */ 794 int val; 795 796 do { 797 if (s->pending == s->pending_buf_size) { 798 if (s->gzhead->hcrc && s->pending > beg) 799 strm->adler = crc32(strm->adler, s->pending_buf + beg, 800 s->pending - beg); 801 flush_pending(strm); 802 beg = s->pending; 803 if (s->pending == s->pending_buf_size) { 804 val = 1; 805 break; 806 } 807 } 808 val = s->gzhead->name[s->gzindex++]; 809 put_byte(s, val); 810 } while (val != 0); 811 if (s->gzhead->hcrc && s->pending > beg) 812 strm->adler = crc32(strm->adler, s->pending_buf + beg, 813 s->pending - beg); 814 if (val == 0) { 815 s->gzindex = 0; 816 s->status = COMMENT_STATE; 817 } 818 } 819 else 820 s->status = COMMENT_STATE; 821 } 822 if (s->status == COMMENT_STATE) { 823 if (s->gzhead->comment != Z_NULL) { 824 uInt beg = s->pending; /* start of bytes to update crc */ 825 int val; 826 827 do { 828 if (s->pending == s->pending_buf_size) { 829 if (s->gzhead->hcrc && s->pending > beg) 830 strm->adler = crc32(strm->adler, s->pending_buf + beg, 831 s->pending - beg); 832 flush_pending(strm); 833 beg = s->pending; 834 if (s->pending == s->pending_buf_size) { 835 val = 1; 836 break; 837 } 838 } 839 val = s->gzhead->comment[s->gzindex++]; 840 put_byte(s, val); 841 } while (val != 0); 842 if (s->gzhead->hcrc && s->pending > beg) 843 strm->adler = crc32(strm->adler, s->pending_buf + beg, 844 s->pending - beg); 845 if (val == 0) 846 s->status = HCRC_STATE; 847 } 848 else 849 s->status = HCRC_STATE; 850 } 851 if (s->status == HCRC_STATE) { 852 if (s->gzhead->hcrc) { 853 if (s->pending + 2 > s->pending_buf_size) 854 flush_pending(strm); 855 if (s->pending + 2 <= s->pending_buf_size) { 856 put_byte(s, (Byte)(strm->adler & 0xff)); 857 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 858 strm->adler = crc32(0L, Z_NULL, 0); 859 s->status = BUSY_STATE; 860 } 861 } 862 else 863 s->status = BUSY_STATE; 864 } 865#endif 866 867 /* Flush as much pending output as possible */ 868 if (s->pending != 0) { 869 flush_pending(strm); 870 if (strm->avail_out == 0) { 871 /* Since avail_out is 0, deflate will be called again with 872 * more output space, but possibly with both pending and 873 * avail_in equal to zero. There won't be anything to do, 874 * but this is not an error situation so make sure we 875 * return OK instead of BUF_ERROR at next call of deflate: 876 */ 877 s->last_flush = -1; 878 return Z_OK; 879 } 880 881 /* Make sure there is something to do and avoid duplicate consecutive 882 * flushes. For repeated and useless calls with Z_FINISH, we keep 883 * returning Z_STREAM_END instead of Z_BUF_ERROR. 884 */ 885 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 886 flush != Z_FINISH) { 887 ERR_RETURN(strm, Z_BUF_ERROR); 888 } 889 890 /* User must not provide more input after the first FINISH: */ 891 if (s->status == FINISH_STATE && strm->avail_in != 0) { 892 ERR_RETURN(strm, Z_BUF_ERROR); 893 } 894 895 /* Start a new block or continue the current one. 896 */ 897 if (strm->avail_in != 0 || s->lookahead != 0 || 898 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 899 block_state bstate; 900 901 bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 902 (s->strategy == Z_RLE ? deflate_rle(s, flush) : 903 (*(configuration_table[s->level].func))(s, flush)); 904 905 if (bstate == finish_started || bstate == finish_done) { 906 s->status = FINISH_STATE; 907 } 908 if (bstate == need_more || bstate == finish_started) { 909 if (strm->avail_out == 0) { 910 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 911 } 912 return Z_OK; 913 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 914 * of deflate should use the same flush parameter to make sure 915 * that the flush is complete. So we don't have to output an 916 * empty block here, this will be done at next call. This also 917 * ensures that for a very small output buffer, we emit at most 918 * one empty block. 919 */ 920 } 921 if (bstate == block_done) { 922 if (flush == Z_PARTIAL_FLUSH) { 923 _tr_align(s); 924 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 925 _tr_stored_block(s, (char*)0, 0L, 0); 926 /* For a full flush, this empty block will be recognized 927 * as a special marker by inflate_sync(). 928 */ 929 if (flush == Z_FULL_FLUSH) { 930 CLEAR_HASH(s); /* forget history */ 931 if (s->lookahead == 0) { 932 s->strstart = 0; 933 s->block_start = 0L; 934 s->insert = 0; 935 } 936 } 937 } 938 flush_pending(strm); 939 if (strm->avail_out == 0) { 940 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 941 return Z_OK; 942 } 943 } 944 } 945 Assert(strm->avail_out > 0, "bug2"); 946 947 if (flush != Z_FINISH) return Z_OK; 948 if (s->wrap <= 0) return Z_STREAM_END; 949 950 /* Write the trailer */ 951#ifdef GZIP 952 if (s->wrap == 2) { 953 put_byte(s, (Byte)(strm->adler & 0xff)); 954 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 955 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 956 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 957 put_byte(s, (Byte)(strm->total_in & 0xff)); 958 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 959 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 960 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 961 } 962 else 963#endif 964 { 965 putShortMSB(s, (uInt)(strm->adler >> 16)); 966 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 967 } 968 flush_pending(strm); 969 /* If avail_out is zero, the application will call deflate again 970 * to flush the rest. 971 */ 972 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 973 return s->pending != 0 ? Z_OK : Z_STREAM_END; 974} 975 976/* ========================================================================= */ 977int ZEXPORT deflateEnd (strm) 978 z_streamp strm; 979{ 980 int status; 981 982 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 983 984 status = strm->state->status; 985 if (status != INIT_STATE && 986 status != EXTRA_STATE && 987 status != NAME_STATE && 988 status != COMMENT_STATE && 989 status != HCRC_STATE && 990 status != BUSY_STATE && 991 status != FINISH_STATE) { 992 return Z_STREAM_ERROR; 993 } 994 995 /* Deallocate in reverse order of allocations: */ 996 TRY_FREE(strm, strm->state->pending_buf); 997 TRY_FREE(strm, strm->state->head); 998 TRY_FREE(strm, strm->state->prev); 999 TRY_FREE(strm, strm->state->window); 1000 1001 ZFREE(strm, strm->state); 1002 strm->state = Z_NULL; 1003 1004 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1005} 1006 1007/* ========================================================================= 1008 * Copy the source state to the destination state. 1009 * To simplify the source, this is not supported for 16-bit MSDOS (which 1010 * doesn't have enough memory anyway to duplicate compression states). 1011 */ 1012int ZEXPORT deflateCopy (dest, source) 1013 z_streamp dest; 1014 z_streamp source; 1015{ 1016#ifdef MAXSEG_64K 1017 return Z_STREAM_ERROR; 1018#else 1019 deflate_state *ds; 1020 deflate_state *ss; 1021 ushf *overlay; 1022 1023 1024 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) { 1025 return Z_STREAM_ERROR; 1026 } 1027 1028 ss = source->state; 1029 1030 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream)); 1031 1032 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1033 if (ds == Z_NULL) return Z_MEM_ERROR; 1034 dest->state = (struct internal_state FAR *) ds; 1035 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state)); 1036 ds->strm = dest; 1037 1038 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1039 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1040 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1041 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); 1042 ds->pending_buf = (uchf *) overlay; 1043 1044 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1045 ds->pending_buf == Z_NULL) { 1046 deflateEnd (dest); 1047 return Z_MEM_ERROR; 1048 } 1049 /* following zmemcpy do not work for 16-bit MSDOS */ 1050 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1051 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos)); 1052 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos)); 1053 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); 1054 1055 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1056 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); 1057 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; 1058 1059 ds->l_desc.dyn_tree = ds->dyn_ltree; 1060 ds->d_desc.dyn_tree = ds->dyn_dtree; 1061 ds->bl_desc.dyn_tree = ds->bl_tree; 1062 1063 return Z_OK; 1064#endif /* MAXSEG_64K */ 1065} 1066 1067/* =========================================================================== 1068 * Read a new buffer from the current input stream, update the adler32 1069 * and total number of bytes read. All deflate() input goes through 1070 * this function so some applications may wish to modify it to avoid 1071 * allocating a large strm->next_in buffer and copying from it. 1072 * (See also flush_pending()). 1073 */ 1074local int read_buf(strm, buf, size) 1075 z_streamp strm; 1076 Bytef *buf; 1077 unsigned size; 1078{ 1079 unsigned len = strm->avail_in; 1080 1081 if (len > size) len = size; 1082 if (len == 0) return 0; 1083 1084 strm->avail_in -= len; 1085 1086 zmemcpy(buf, strm->next_in, len); 1087 if (strm->state->wrap == 1) { 1088 strm->adler = adler32(strm->adler, buf, len); 1089 } 1090#ifdef GZIP 1091 else if (strm->state->wrap == 2) { 1092 strm->adler = crc32(strm->adler, buf, len); 1093 } 1094#endif 1095 strm->next_in += len; 1096 strm->total_in += len; 1097 1098 return (int)len; 1099} 1100 1101/* =========================================================================== 1102 * Initialize the "longest match" routines for a new zlib stream 1103 */ 1104local void lm_init (s) 1105 deflate_state *s; 1106{ 1107 s->window_size = (ulg)2L*s->w_size; 1108 1109 CLEAR_HASH(s); 1110 1111 /* Set the default configuration parameters: 1112 */ 1113 s->max_lazy_match = configuration_table[s->level].max_lazy; 1114 s->good_match = configuration_table[s->level].good_length; 1115 s->nice_match = configuration_table[s->level].nice_length; 1116 s->max_chain_length = configuration_table[s->level].max_chain; 1117 1118 s->strstart = 0; 1119 s->block_start = 0L; 1120 s->lookahead = 0; 1121 s->insert = 0; 1122 s->match_length = s->prev_length = MIN_MATCH-1; 1123 s->match_available = 0; 1124 s->ins_h = 0; 1125#ifndef FASTEST 1126#ifdef ASMV 1127 match_init(); /* initialize the asm code */ 1128#endif 1129#endif 1130} 1131 1132#ifndef FASTEST 1133/* =========================================================================== 1134 * Set match_start to the longest match starting at the given string and 1135 * return its length. Matches shorter or equal to prev_length are discarded, 1136 * in which case the result is equal to prev_length and match_start is 1137 * garbage. 1138 * IN assertions: cur_match is the head of the hash chain for the current 1139 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1140 * OUT assertion: the match length is not greater than s->lookahead. 1141 */ 1142#ifndef ASMV 1143/* For 80x86 and 680x0, an optimized version will be provided in match.asm or 1144 * match.S. The code will be functionally equivalent. 1145 */ 1146local uInt longest_match(s, cur_match) 1147 deflate_state *s; 1148 IPos cur_match; /* current match */ 1149{ 1150 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1151 register Bytef *scan = s->window + s->strstart; /* current string */ 1152 register Bytef *match; /* matched string */ 1153 register int len; /* length of current match */ 1154 int best_len = s->prev_length; /* best match length so far */ 1155 int nice_match = s->nice_match; /* stop if match long enough */ 1156 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1157 s->strstart - (IPos)MAX_DIST(s) : NIL; 1158 /* Stop when cur_match becomes <= limit. To simplify the code, 1159 * we prevent matches with the string of window index 0. 1160 */ 1161 Posf *prev = s->prev; 1162 uInt wmask = s->w_mask; 1163 1164#ifdef UNALIGNED_OK 1165 /* Compare two bytes at a time. Note: this is not always beneficial. 1166 * Try with and without -DUNALIGNED_OK to check. 1167 */ 1168 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1169 register ush scan_start = *(ushf*)scan; 1170 register ush scan_end = *(ushf*)(scan+best_len-1); 1171#else 1172 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1173 register Byte scan_end1 = scan[best_len-1]; 1174 register Byte scan_end = scan[best_len]; 1175#endif 1176 1177 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1178 * It is easy to get rid of this optimization if necessary. 1179 */ 1180 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1181 1182 /* Do not waste too much time if we already have a good match: */ 1183 if (s->prev_length >= s->good_match) { 1184 chain_length >>= 2; 1185 } 1186 /* Do not look for matches beyond the end of the input. This is necessary 1187 * to make deflate deterministic. 1188 */ 1189 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; 1190 1191 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1192 1193 do { 1194 Assert(cur_match < s->strstart, "no future"); 1195 match = s->window + cur_match; 1196 1197 /* Skip to next match if the match length cannot increase 1198 * or if the match length is less than 2. Note that the checks below 1199 * for insufficient lookahead only occur occasionally for performance 1200 * reasons. Therefore uninitialized memory will be accessed, and 1201 * conditional jumps will be made that depend on those values. 1202 * However the length of the match is limited to the lookahead, so 1203 * the output of deflate is not affected by the uninitialized values. 1204 */ 1205#if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1206 /* This code assumes sizeof(unsigned short) == 2. Do not use 1207 * UNALIGNED_OK if your compiler uses a different size. 1208 */ 1209 if (*(ushf*)(match+best_len-1) != scan_end || 1210 *(ushf*)match != scan_start) continue; 1211 1212 /* It is not necessary to compare scan[2] and match[2] since they are 1213 * always equal when the other bytes match, given that the hash keys 1214 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1215 * strstart+3, +5, ... up to strstart+257. We check for insufficient 1216 * lookahead only every 4th comparison; the 128th check will be made 1217 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is 1218 * necessary to put more guard bytes at the end of the window, or 1219 * to check more often for insufficient lookahead. 1220 */ 1221 Assert(scan[2] == match[2], "scan[2]?"); 1222 scan++, match++; 1223 do { 1224 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1225 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1226 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1227 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1228 scan < strend); 1229 /* The funny "do {}" generates better code on most compilers */ 1230 1231 /* Here, scan <= window+strstart+257 */ 1232 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1233 if (*scan == *match) scan++; 1234 1235 len = (MAX_MATCH - 1) - (int)(strend-scan); 1236 scan = strend - (MAX_MATCH-1); 1237 1238#else /* UNALIGNED_OK */ 1239 1240 if (match[best_len] != scan_end || 1241 match[best_len-1] != scan_end1 || 1242 *match != *scan || 1243 *++match != scan[1]) continue; 1244 1245 /* The check at best_len-1 can be removed because it will be made 1246 * again later. (This heuristic is not always a win.) 1247 * It is not necessary to compare scan[2] and match[2] since they 1248 * are always equal when the other bytes match, given that 1249 * the hash keys are equal and that HASH_BITS >= 8. 1250 */ 1251 scan += 2, match++; 1252 Assert(*scan == *match, "match[2]?"); 1253 1254 /* We check for insufficient lookahead only every 8th comparison; 1255 * the 256th check will be made at strstart+258. 1256 */ 1257 do { 1258 } while (*++scan == *++match && *++scan == *++match && 1259 *++scan == *++match && *++scan == *++match && 1260 *++scan == *++match && *++scan == *++match && 1261 *++scan == *++match && *++scan == *++match && 1262 scan < strend); 1263 1264 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1265 1266 len = MAX_MATCH - (int)(strend - scan); 1267 scan = strend - MAX_MATCH; 1268 1269#endif /* UNALIGNED_OK */ 1270 1271 if (len > best_len) { 1272 s->match_start = cur_match; 1273 best_len = len; 1274 if (len >= nice_match) break; 1275#ifdef UNALIGNED_OK 1276 scan_end = *(ushf*)(scan+best_len-1); 1277#else 1278 scan_end1 = scan[best_len-1]; 1279 scan_end = scan[best_len]; 1280#endif 1281 } 1282 } while ((cur_match = prev[cur_match & wmask]) > limit 1283 && --chain_length != 0); 1284 1285 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1286 return s->lookahead; 1287} 1288#endif /* ASMV */ 1289 1290#else /* FASTEST */ 1291 1292/* --------------------------------------------------------------------------- 1293 * Optimized version for FASTEST only 1294 */ 1295local uInt longest_match(s, cur_match) 1296 deflate_state *s; 1297 IPos cur_match; /* current match */ 1298{ 1299 register Bytef *scan = s->window + s->strstart; /* current string */ 1300 register Bytef *match; /* matched string */ 1301 register int len; /* length of current match */ 1302 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1303 1304 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1305 * It is easy to get rid of this optimization if necessary. 1306 */ 1307 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1308 1309 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1310 1311 Assert(cur_match < s->strstart, "no future"); 1312 1313 match = s->window + cur_match; 1314 1315 /* Return failure if the match length is less than 2: 1316 */ 1317 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1318 1319 /* The check at best_len-1 can be removed because it will be made 1320 * again later. (This heuristic is not always a win.) 1321 * It is not necessary to compare scan[2] and match[2] since they 1322 * are always equal when the other bytes match, given that 1323 * the hash keys are equal and that HASH_BITS >= 8. 1324 */ 1325 scan += 2, match += 2; 1326 Assert(*scan == *match, "match[2]?"); 1327 1328 /* We check for insufficient lookahead only every 8th comparison; 1329 * the 256th check will be made at strstart+258. 1330 */ 1331 do { 1332 } while (*++scan == *++match && *++scan == *++match && 1333 *++scan == *++match && *++scan == *++match && 1334 *++scan == *++match && *++scan == *++match && 1335 *++scan == *++match && *++scan == *++match && 1336 scan < strend); 1337 1338 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1339 1340 len = MAX_MATCH - (int)(strend - scan); 1341 1342 if (len < MIN_MATCH) return MIN_MATCH - 1; 1343 1344 s->match_start = cur_match; 1345 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1346} 1347 1348#endif /* FASTEST */ 1349 1350#ifdef DEBUG 1351/* =========================================================================== 1352 * Check that the match at match_start is indeed a match. 1353 */ 1354local void check_match(s, start, match, length) 1355 deflate_state *s; 1356 IPos start, match; 1357 int length; 1358{ 1359 /* check that the match is indeed a match */ 1360 if (zmemcmp(s->window + match, 1361 s->window + start, length) != EQUAL) { 1362 fprintf(stderr, " start %u, match %u, length %d\n", 1363 start, match, length); 1364 do { 1365 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); 1366 } while (--length != 0); 1367 z_error("invalid match"); 1368 } 1369 if (z_verbose > 1) { 1370 fprintf(stderr,"\\[%d,%d]", start-match, length); 1371 do { putc(s->window[start++], stderr); } while (--length != 0); 1372 } 1373} 1374#else 1375# define check_match(s, start, match, length) 1376#endif /* DEBUG */ 1377 1378/* =========================================================================== 1379 * Fill the window when the lookahead becomes insufficient. 1380 * Updates strstart and lookahead. 1381 * 1382 * IN assertion: lookahead < MIN_LOOKAHEAD 1383 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 1384 * At least one byte has been read, or avail_in == 0; reads are 1385 * performed for at least two bytes (required for the zip translate_eol 1386 * option -- not supported here). 1387 */ 1388local void fill_window(s) 1389 deflate_state *s; 1390{ 1391 register unsigned n, m; 1392 register Posf *p; 1393 unsigned more; /* Amount of free space at the end of the window. */ 1394 uInt wsize = s->w_size; 1395 1396 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); 1397 1398 do { 1399 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 1400 1401 /* Deal with !@#$% 64K limit: */ 1402 if (sizeof(int) <= 2) { 1403 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 1404 more = wsize; 1405 1406 } else if (more == (unsigned)(-1)) { 1407 /* Very unlikely, but possible on 16 bit machine if 1408 * strstart == 0 && lookahead == 1 (input done a byte at time) 1409 */ 1410 more--; 1411 } 1412 } 1413 1414 /* If the window is almost full and there is insufficient lookahead, 1415 * move the upper half to the lower one to make room in the upper half. 1416 */ 1417 if (s->strstart >= wsize+MAX_DIST(s)) { 1418 1419 zmemcpy(s->window, s->window+wsize, (unsigned)wsize); 1420 s->match_start -= wsize; 1421 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 1422 s->block_start -= (long) wsize; 1423 1424 /* Slide the hash table (could be avoided with 32 bit values 1425 at the expense of memory usage). We slide even when level == 0 1426 to keep the hash table consistent if we switch back to level > 0 1427 later. (Using level 0 permanently is not an optimal usage of 1428 zlib, so we don't care about this pathological case.) 1429 */ 1430 n = s->hash_size; 1431 p = &s->head[n]; 1432 do { 1433 m = *--p; 1434 *p = (Pos)(m >= wsize ? m-wsize : NIL); 1435 } while (--n); 1436 1437 n = wsize; 1438#ifndef FASTEST 1439 p = &s->prev[n]; 1440 do { 1441 m = *--p; 1442 *p = (Pos)(m >= wsize ? m-wsize : NIL); 1443 /* If n is not on any hash chain, prev[n] is garbage but 1444 * its value will never be used. 1445 */ 1446 } while (--n); 1447#endif 1448 more += wsize; 1449 } 1450 if (s->strm->avail_in == 0) break; 1451 1452 /* If there was no sliding: 1453 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 1454 * more == window_size - lookahead - strstart 1455 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 1456 * => more >= window_size - 2*WSIZE + 2 1457 * In the BIG_MEM or MMAP case (not yet supported), 1458 * window_size == input_size + MIN_LOOKAHEAD && 1459 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 1460 * Otherwise, window_size == 2*WSIZE so more >= 2. 1461 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 1462 */ 1463 Assert(more >= 2, "more < 2"); 1464 1465 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 1466 s->lookahead += n; 1467 1468 /* Initialize the hash value now that we have some input: */ 1469 if (s->lookahead + s->insert >= MIN_MATCH) { 1470 uInt str = s->strstart - s->insert; 1471 s->ins_h = s->window[str]; 1472 UPDATE_HASH(s, s->ins_h, s->window[str + 1]); 1473#if MIN_MATCH != 3 1474 Call UPDATE_HASH() MIN_MATCH-3 more times 1475#endif 1476 while (s->insert) { 1477 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 1478#ifndef FASTEST 1479 s->prev[str & s->w_mask] = s->head[s->ins_h]; 1480#endif 1481 s->head[s->ins_h] = (Pos)str; 1482 str++; 1483 s->insert--; 1484 if (s->lookahead + s->insert < MIN_MATCH) 1485 break; 1486 } 1487 } 1488 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 1489 * but this is not important since only literal bytes will be emitted. 1490 */ 1491 1492 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 1493 1494 /* If the WIN_INIT bytes after the end of the current data have never been 1495 * written, then zero those bytes in order to avoid memory check reports of 1496 * the use of uninitialized (or uninitialised as Julian writes) bytes by 1497 * the longest match routines. Update the high water mark for the next 1498 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 1499 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 1500 */ 1501 if (s->high_water < s->window_size) { 1502 ulg curr = s->strstart + (ulg)(s->lookahead); 1503 ulg init; 1504 1505 if (s->high_water < curr) { 1506 /* Previous high water mark below current data -- zero WIN_INIT 1507 * bytes or up to end of window, whichever is less. 1508 */ 1509 init = s->window_size - curr; 1510 if (init > WIN_INIT) 1511 init = WIN_INIT; 1512 zmemzero(s->window + curr, (unsigned)init); 1513 s->high_water = curr + init; 1514 } 1515 else if (s->high_water < (ulg)curr + WIN_INIT) { 1516 /* High water mark at or above current data, but below current data 1517 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 1518 * to end of window, whichever is less. 1519 */ 1520 init = (ulg)curr + WIN_INIT - s->high_water; 1521 if (init > s->window_size - s->high_water) 1522 init = s->window_size - s->high_water; 1523 zmemzero(s->window + s->high_water, (unsigned)init); 1524 s->high_water += init; 1525 } 1526 } 1527 1528 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1529 "not enough room for search"); 1530} 1531 1532/* =========================================================================== 1533 * Flush the current block, with given end-of-file flag. 1534 * IN assertion: strstart is set to the end of the current match. 1535 */ 1536#define FLUSH_BLOCK_ONLY(s, last) { \ 1537 _tr_flush_block(s, (s->block_start >= 0L ? \ 1538 (charf *)&s->window[(unsigned)s->block_start] : \ 1539 (charf *)Z_NULL), \ 1540 (ulg)((long)s->strstart - s->block_start), \ 1541 (last)); \ 1542 s->block_start = s->strstart; \ 1543 flush_pending(s->strm); \ 1544 Tracev((stderr,"[FLUSH]")); \ 1545} 1546 1547/* Same but force premature exit if necessary. */ 1548#define FLUSH_BLOCK(s, last) { \ 1549 FLUSH_BLOCK_ONLY(s, last); \ 1550 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1551} 1552 1553/* =========================================================================== 1554 * Copy without compression as much as possible from the input stream, return 1555 * the current block state. 1556 * This function does not insert new strings in the dictionary since 1557 * uncompressible data is probably not useful. This function is used 1558 * only for the level=0 compression option. 1559 * NOTE: this function should be optimized to avoid extra copying from 1560 * window to pending_buf. 1561 */ 1562local block_state deflate_stored(s, flush) 1563 deflate_state *s; 1564 int flush; 1565{ 1566 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited 1567 * to pending_buf_size, and each stored block has a 5 byte header: 1568 */ 1569 ulg max_block_size = 0xffff; 1570 ulg max_start; 1571 1572 if (max_block_size > s->pending_buf_size - 5) { 1573 max_block_size = s->pending_buf_size - 5; 1574 } 1575 1576 /* Copy as much as possible from input to output: */ 1577 for (;;) { 1578 /* Fill the window as much as possible: */ 1579 if (s->lookahead <= 1) { 1580 1581 Assert(s->strstart < s->w_size+MAX_DIST(s) || 1582 s->block_start >= (long)s->w_size, "slide too late"); 1583 1584 fill_window(s); 1585 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more; 1586 1587 if (s->lookahead == 0) break; /* flush the current block */ 1588 } 1589 Assert(s->block_start >= 0L, "block gone"); 1590 1591 s->strstart += s->lookahead; 1592 s->lookahead = 0; 1593 1594 /* Emit a stored block if pending_buf will be full: */ 1595 max_start = s->block_start + max_block_size; 1596 if (s->strstart == 0 || (ulg)s->strstart >= max_start) { 1597 /* strstart == 0 is possible when wraparound on 16-bit machine */ 1598 s->lookahead = (uInt)(s->strstart - max_start); 1599 s->strstart = (uInt)max_start; 1600 FLUSH_BLOCK(s, 0); 1601 } 1602 /* Flush if we may have to slide, otherwise block_start may become 1603 * negative and the data will be gone: 1604 */ 1605 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) { 1606 FLUSH_BLOCK(s, 0); 1607 } 1608 } 1609 s->insert = 0; 1610 if (flush == Z_FINISH) { 1611 FLUSH_BLOCK(s, 1); 1612 return finish_done; 1613 } 1614 if ((long)s->strstart > s->block_start) 1615 FLUSH_BLOCK(s, 0); 1616 return block_done; 1617} 1618 1619/* =========================================================================== 1620 * Compress as much as possible from the input stream, return the current 1621 * block state. 1622 * This function does not perform lazy evaluation of matches and inserts 1623 * new strings in the dictionary only for unmatched strings or for short 1624 * matches. It is used only for the fast compression options. 1625 */ 1626local block_state deflate_fast(s, flush) 1627 deflate_state *s; 1628 int flush; 1629{ 1630 IPos hash_head; /* head of the hash chain */ 1631 int bflush; /* set if current block must be flushed */ 1632 1633 for (;;) { 1634 /* Make sure that we always have enough lookahead, except 1635 * at the end of the input file. We need MAX_MATCH bytes 1636 * for the next match, plus MIN_MATCH bytes to insert the 1637 * string following the next match. 1638 */ 1639 if (s->lookahead < MIN_LOOKAHEAD) { 1640 fill_window(s); 1641 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1642 return need_more; 1643 } 1644 if (s->lookahead == 0) break; /* flush the current block */ 1645 } 1646 1647 /* Insert the string window[strstart .. strstart+2] in the 1648 * dictionary, and set hash_head to the head of the hash chain: 1649 */ 1650 hash_head = NIL; 1651 if (s->lookahead >= MIN_MATCH) { 1652 INSERT_STRING(s, s->strstart, hash_head); 1653 } 1654 1655 /* Find the longest match, discarding those <= prev_length. 1656 * At this point we have always match_length < MIN_MATCH 1657 */ 1658 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1659 /* To simplify the code, we prevent matches with the string 1660 * of window index 0 (in particular we have to avoid a match 1661 * of the string with itself at the start of the input file). 1662 */ 1663 s->match_length = longest_match (s, hash_head); 1664 /* longest_match() sets match_start */ 1665 } 1666 if (s->match_length >= MIN_MATCH) { 1667 check_match(s, s->strstart, s->match_start, s->match_length); 1668 1669 _tr_tally_dist(s, s->strstart - s->match_start, 1670 s->match_length - MIN_MATCH, bflush); 1671 1672 s->lookahead -= s->match_length; 1673 1674 /* Insert new strings in the hash table only if the match length 1675 * is not too large. This saves time but degrades compression. 1676 */ 1677#ifndef FASTEST 1678 if (s->match_length <= s->max_insert_length && 1679 s->lookahead >= MIN_MATCH) { 1680 s->match_length--; /* string at strstart already in table */ 1681 do { 1682 s->strstart++; 1683 INSERT_STRING(s, s->strstart, hash_head); 1684 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1685 * always MIN_MATCH bytes ahead. 1686 */ 1687 } while (--s->match_length != 0); 1688 s->strstart++; 1689 } else 1690#endif 1691 { 1692 s->strstart += s->match_length; 1693 s->match_length = 0; 1694 s->ins_h = s->window[s->strstart]; 1695 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); 1696#if MIN_MATCH != 3 1697 Call UPDATE_HASH() MIN_MATCH-3 more times 1698#endif 1699 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1700 * matter since it will be recomputed at next deflate call. 1701 */ 1702 } 1703 } else { 1704 /* No match, output a literal byte */ 1705 Tracevv((stderr,"%c", s->window[s->strstart])); 1706 _tr_tally_lit (s, s->window[s->strstart], bflush); 1707 s->lookahead--; 1708 s->strstart++; 1709 } 1710 if (bflush) FLUSH_BLOCK(s, 0); 1711 } 1712 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1713 if (flush == Z_FINISH) { 1714 FLUSH_BLOCK(s, 1); 1715 return finish_done; 1716 } 1717 if (s->last_lit) 1718 FLUSH_BLOCK(s, 0); 1719 return block_done; 1720} 1721 1722#ifndef FASTEST 1723/* =========================================================================== 1724 * Same as above, but achieves better compression. We use a lazy 1725 * evaluation for matches: a match is finally adopted only if there is 1726 * no better match at the next window position. 1727 */ 1728local block_state deflate_slow(s, flush) 1729 deflate_state *s; 1730 int flush; 1731{ 1732 IPos hash_head; /* head of hash chain */ 1733 int bflush; /* set if current block must be flushed */ 1734 1735 /* Process the input block. */ 1736 for (;;) { 1737 /* Make sure that we always have enough lookahead, except 1738 * at the end of the input file. We need MAX_MATCH bytes 1739 * for the next match, plus MIN_MATCH bytes to insert the 1740 * string following the next match. 1741 */ 1742 if (s->lookahead < MIN_LOOKAHEAD) { 1743 fill_window(s); 1744 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1745 return need_more; 1746 } 1747 if (s->lookahead == 0) break; /* flush the current block */ 1748 } 1749 1750 /* Insert the string window[strstart .. strstart+2] in the 1751 * dictionary, and set hash_head to the head of the hash chain: 1752 */ 1753 hash_head = NIL; 1754 if (s->lookahead >= MIN_MATCH) { 1755 INSERT_STRING(s, s->strstart, hash_head); 1756 } 1757 1758 /* Find the longest match, discarding those <= prev_length. 1759 */ 1760 s->prev_length = s->match_length, s->prev_match = s->match_start; 1761 s->match_length = MIN_MATCH-1; 1762 1763 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1764 s->strstart - hash_head <= MAX_DIST(s)) { 1765 /* To simplify the code, we prevent matches with the string 1766 * of window index 0 (in particular we have to avoid a match 1767 * of the string with itself at the start of the input file). 1768 */ 1769 s->match_length = longest_match (s, hash_head); 1770 /* longest_match() sets match_start */ 1771 1772 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1773#if TOO_FAR <= 32767 1774 || (s->match_length == MIN_MATCH && 1775 s->strstart - s->match_start > TOO_FAR) 1776#endif 1777 )) { 1778 1779 /* If prev_match is also MIN_MATCH, match_start is garbage 1780 * but we will ignore the current match anyway. 1781 */ 1782 s->match_length = MIN_MATCH-1; 1783 } 1784 } 1785 /* If there was a match at the previous step and the current 1786 * match is not better, output the previous match: 1787 */ 1788 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1789 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1790 /* Do not insert strings in hash table beyond this. */ 1791 1792 check_match(s, s->strstart-1, s->prev_match, s->prev_length); 1793 1794 _tr_tally_dist(s, s->strstart -1 - s->prev_match, 1795 s->prev_length - MIN_MATCH, bflush); 1796 1797 /* Insert in hash table all strings up to the end of the match. 1798 * strstart-1 and strstart are already inserted. If there is not 1799 * enough lookahead, the last two strings are not inserted in 1800 * the hash table. 1801 */ 1802 s->lookahead -= s->prev_length-1; 1803 s->prev_length -= 2; 1804 do { 1805 if (++s->strstart <= max_insert) { 1806 INSERT_STRING(s, s->strstart, hash_head); 1807 } 1808 } while (--s->prev_length != 0); 1809 s->match_available = 0; 1810 s->match_length = MIN_MATCH-1; 1811 s->strstart++; 1812 1813 if (bflush) FLUSH_BLOCK(s, 0); 1814 1815 } else if (s->match_available) { 1816 /* If there was no match at the previous position, output a 1817 * single literal. If there was a match but the current match 1818 * is longer, truncate the previous match to a single literal. 1819 */ 1820 Tracevv((stderr,"%c", s->window[s->strstart-1])); 1821 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 1822 if (bflush) { 1823 FLUSH_BLOCK_ONLY(s, 0); 1824 } 1825 s->strstart++; 1826 s->lookahead--; 1827 if (s->strm->avail_out == 0) return need_more; 1828 } else { 1829 /* There is no previous match to compare with, wait for 1830 * the next step to decide. 1831 */ 1832 s->match_available = 1; 1833 s->strstart++; 1834 s->lookahead--; 1835 } 1836 } 1837 Assert (flush != Z_NO_FLUSH, "no flush?"); 1838 if (s->match_available) { 1839 Tracevv((stderr,"%c", s->window[s->strstart-1])); 1840 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 1841 s->match_available = 0; 1842 } 1843 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1844 if (flush == Z_FINISH) { 1845 FLUSH_BLOCK(s, 1); 1846 return finish_done; 1847 } 1848 if (s->last_lit) 1849 FLUSH_BLOCK(s, 0); 1850 return block_done; 1851} 1852#endif /* FASTEST */ 1853 1854/* =========================================================================== 1855 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 1856 * one. Do not maintain a hash table. (It will be regenerated if this run of 1857 * deflate switches away from Z_RLE.) 1858 */ 1859local block_state deflate_rle(s, flush) 1860 deflate_state *s; 1861 int flush; 1862{ 1863 int bflush; /* set if current block must be flushed */ 1864 uInt prev; /* byte at distance one to match */ 1865 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 1866 1867 for (;;) { 1868 /* Make sure that we always have enough lookahead, except 1869 * at the end of the input file. We need MAX_MATCH bytes 1870 * for the longest run, plus one for the unrolled loop. 1871 */ 1872 if (s->lookahead <= MAX_MATCH) { 1873 fill_window(s); 1874 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 1875 return need_more; 1876 } 1877 if (s->lookahead == 0) break; /* flush the current block */ 1878 } 1879 1880 /* See how many times the previous byte repeats */ 1881 s->match_length = 0; 1882 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 1883 scan = s->window + s->strstart - 1; 1884 prev = *scan; 1885 if (prev == *++scan && prev == *++scan && prev == *++scan) { 1886 strend = s->window + s->strstart + MAX_MATCH; 1887 do { 1888 } while (prev == *++scan && prev == *++scan && 1889 prev == *++scan && prev == *++scan && 1890 prev == *++scan && prev == *++scan && 1891 prev == *++scan && prev == *++scan && 1892 scan < strend); 1893 s->match_length = MAX_MATCH - (int)(strend - scan); 1894 if (s->match_length > s->lookahead) 1895 s->match_length = s->lookahead; 1896 } 1897 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan"); 1898 } 1899 1900 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 1901 if (s->match_length >= MIN_MATCH) { 1902 check_match(s, s->strstart, s->strstart - 1, s->match_length); 1903 1904 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 1905 1906 s->lookahead -= s->match_length; 1907 s->strstart += s->match_length; 1908 s->match_length = 0; 1909 } else { 1910 /* No match, output a literal byte */ 1911 Tracevv((stderr,"%c", s->window[s->strstart])); 1912 _tr_tally_lit (s, s->window[s->strstart], bflush); 1913 s->lookahead--; 1914 s->strstart++; 1915 } 1916 if (bflush) FLUSH_BLOCK(s, 0); 1917 } 1918 s->insert = 0; 1919 if (flush == Z_FINISH) { 1920 FLUSH_BLOCK(s, 1); 1921 return finish_done; 1922 } 1923 if (s->last_lit) 1924 FLUSH_BLOCK(s, 0); 1925 return block_done; 1926} 1927 1928/* =========================================================================== 1929 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 1930 * (It will be regenerated if this run of deflate switches away from Huffman.) 1931 */ 1932local block_state deflate_huff(s, flush) 1933 deflate_state *s; 1934 int flush; 1935{ 1936 int bflush; /* set if current block must be flushed */ 1937 1938 for (;;) { 1939 /* Make sure that we have a literal to write. */ 1940 if (s->lookahead == 0) { 1941 fill_window(s); 1942 if (s->lookahead == 0) { 1943 if (flush == Z_NO_FLUSH) 1944 return need_more; 1945 break; /* flush the current block */ 1946 } 1947 } 1948 1949 /* Output a literal byte */ 1950 s->match_length = 0; 1951 Tracevv((stderr,"%c", s->window[s->strstart])); 1952 _tr_tally_lit (s, s->window[s->strstart], bflush); 1953 s->lookahead--; 1954 s->strstart++; 1955 if (bflush) FLUSH_BLOCK(s, 0); 1956 } 1957 s->insert = 0; 1958 if (flush == Z_FINISH) { 1959 FLUSH_BLOCK(s, 1); 1960 return finish_done; 1961 } 1962 if (s->last_lit) 1963 FLUSH_BLOCK(s, 0); 1964 return block_done; 1965} 1966