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 54 const 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 */ 66 typedef enum { 67 need_more, /* block not completed, need more input or more output */ 68 block_done, /* block flush performed */ 69 finish_started, /* finish started, need only more output at next deflate */ 70 finish_done /* finish done, accept no more input or output */ 71 } block_state; 72 73 typedef block_state (*compress_func) OF((deflate_state *s, int flush)); 74 /* Compression function. Returns the block state after the call. */ 75 76 local void fill_window OF((deflate_state *s)); 77 local block_state deflate_stored OF((deflate_state *s, int flush)); 78 local block_state deflate_fast OF((deflate_state *s, int flush)); 79 #ifndef FASTEST 80 local block_state deflate_slow OF((deflate_state *s, int flush)); 81 #endif 82 local block_state deflate_rle OF((deflate_state *s, int flush)); 83 local block_state deflate_huff OF((deflate_state *s, int flush)); 84 local void lm_init OF((deflate_state *s)); 85 local void putShortMSB OF((deflate_state *s, uInt b)); 86 local void flush_pending OF((z_streamp strm)); 87 local 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 92 local uInt longest_match OF((deflate_state *s, IPos cur_match)); 93 #endif 94 95 #ifdef DEBUG 96 local void check_match OF((deflate_state *s, IPos start, IPos match, 97 int length)); 98 #endif 99 100 /* =========================================================================== 101 * Local data 102 */ 103 104 #define NIL 0 105 /* Tail of hash chains */ 106 107 #ifndef TOO_FAR 108 # define TOO_FAR 4096 109 #endif 110 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ 111 112 /* Values for max_lazy_match, good_match and max_chain_length, depending on 113 * the desired pack level (0..9). The values given below have been tuned to 114 * exclude worst case performance for pathological files. Better values may be 115 * found for specific files. 116 */ 117 typedef struct config_s { 118 ush good_length; /* reduce lazy search above this match length */ 119 ush max_lazy; /* do not perform lazy search above this match length */ 120 ush nice_length; /* quit search above this match length */ 121 ush max_chain; 122 compress_func func; 123 } config; 124 125 #ifdef FASTEST 126 local const config configuration_table[2] = { 127 /* good lazy nice chain */ 128 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 129 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ 130 #else 131 local const config configuration_table[10] = { 132 /* good lazy nice chain */ 133 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 134 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ 135 /* 2 */ {4, 5, 16, 8, deflate_fast}, 136 /* 3 */ {4, 6, 32, 32, deflate_fast}, 137 138 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ 139 /* 5 */ {8, 16, 32, 32, deflate_slow}, 140 /* 6 */ {8, 16, 128, 128, deflate_slow}, 141 /* 7 */ {8, 32, 128, 256, deflate_slow}, 142 /* 8 */ {32, 128, 258, 1024, deflate_slow}, 143 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ 144 #endif 145 146 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 147 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different 148 * meaning. 149 */ 150 151 #define EQUAL 0 152 /* result of memcmp for equal strings */ 153 154 #ifndef NO_DUMMY_DECL 155 struct 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 /* ========================================================================= */ 201 int 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 /* ========================================================================= */ 213 int 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 = 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 /* ========================================================================= */ 323 int 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 z_const 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 = (z_const 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 /* ========================================================================= */ 392 int 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 /* ========================================================================= */ 427 int 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 /* ========================================================================= */ 439 int 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 /* ========================================================================= */ 450 int 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 /* ========================================================================= */ 464 int 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 /* ========================================================================= */ 490 int 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 if (err == Z_BUF_ERROR && s->pending == 0) 517 err = Z_OK; 518 } 519 if (s->level != level) { 520 s->level = level; 521 s->max_lazy_match = configuration_table[level].max_lazy; 522 s->good_match = configuration_table[level].good_length; 523 s->nice_match = configuration_table[level].nice_length; 524 s->max_chain_length = configuration_table[level].max_chain; 525 } 526 s->strategy = strategy; 527 return err; 528 } 529 530 /* ========================================================================= */ 531 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain) 532 z_streamp strm; 533 int good_length; 534 int max_lazy; 535 int nice_length; 536 int max_chain; 537 { 538 deflate_state *s; 539 540 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 541 s = strm->state; 542 s->good_match = good_length; 543 s->max_lazy_match = max_lazy; 544 s->nice_match = nice_length; 545 s->max_chain_length = max_chain; 546 return Z_OK; 547 } 548 549 /* ========================================================================= 550 * For the default windowBits of 15 and memLevel of 8, this function returns 551 * a close to exact, as well as small, upper bound on the compressed size. 552 * They are coded as constants here for a reason--if the #define's are 553 * changed, then this function needs to be changed as well. The return 554 * value for 15 and 8 only works for those exact settings. 555 * 556 * For any setting other than those defaults for windowBits and memLevel, 557 * the value returned is a conservative worst case for the maximum expansion 558 * resulting from using fixed blocks instead of stored blocks, which deflate 559 * can emit on compressed data for some combinations of the parameters. 560 * 561 * This function could be more sophisticated to provide closer upper bounds for 562 * every combination of windowBits and memLevel. But even the conservative 563 * upper bound of about 14% expansion does not seem onerous for output buffer 564 * allocation. 565 */ 566 uLong ZEXPORT deflateBound(strm, sourceLen) 567 z_streamp strm; 568 uLong sourceLen; 569 { 570 deflate_state *s; 571 uLong complen, wraplen; 572 Bytef *str; 573 574 /* conservative upper bound for compressed data */ 575 complen = sourceLen + 576 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5; 577 578 /* if can't get parameters, return conservative bound plus zlib wrapper */ 579 if (strm == Z_NULL || strm->state == Z_NULL) 580 return complen + 6; 581 582 /* compute wrapper length */ 583 s = strm->state; 584 switch (s->wrap) { 585 case 0: /* raw deflate */ 586 wraplen = 0; 587 break; 588 case 1: /* zlib wrapper */ 589 wraplen = 6 + (s->strstart ? 4 : 0); 590 break; 591 case 2: /* gzip wrapper */ 592 wraplen = 18; 593 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 594 if (s->gzhead->extra != Z_NULL) 595 wraplen += 2 + s->gzhead->extra_len; 596 str = s->gzhead->name; 597 if (str != Z_NULL) 598 do { 599 wraplen++; 600 } while (*str++); 601 str = s->gzhead->comment; 602 if (str != Z_NULL) 603 do { 604 wraplen++; 605 } while (*str++); 606 if (s->gzhead->hcrc) 607 wraplen += 2; 608 } 609 break; 610 default: /* for compiler happiness */ 611 wraplen = 6; 612 } 613 614 /* if not default parameters, return conservative bound */ 615 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 616 return complen + wraplen; 617 618 /* default settings: return tight bound for that case */ 619 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 620 (sourceLen >> 25) + 13 - 6 + wraplen; 621 } 622 623 /* ========================================================================= 624 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 625 * IN assertion: the stream state is correct and there is enough room in 626 * pending_buf. 627 */ 628 local void putShortMSB (s, b) 629 deflate_state *s; 630 uInt b; 631 { 632 put_byte(s, (Byte)(b >> 8)); 633 put_byte(s, (Byte)(b & 0xff)); 634 } 635 636 /* ========================================================================= 637 * Flush as much pending output as possible. All deflate() output goes 638 * through this function so some applications may wish to modify it 639 * to avoid allocating a large strm->next_out buffer and copying into it. 640 * (See also read_buf()). 641 */ 642 local void flush_pending(strm) 643 z_streamp strm; 644 { 645 unsigned len; 646 deflate_state *s = strm->state; 647 648 _tr_flush_bits(s); 649 len = s->pending; 650 if (len > strm->avail_out) len = strm->avail_out; 651 if (len == 0) return; 652 653 zmemcpy(strm->next_out, s->pending_out, len); 654 strm->next_out += len; 655 s->pending_out += len; 656 strm->total_out += len; 657 strm->avail_out -= len; 658 s->pending -= len; 659 if (s->pending == 0) { 660 s->pending_out = s->pending_buf; 661 } 662 } 663 664 /* ========================================================================= */ 665 int ZEXPORT deflate (strm, flush) 666 z_streamp strm; 667 int flush; 668 { 669 int old_flush; /* value of flush param for previous deflate call */ 670 deflate_state *s; 671 672 if (strm == Z_NULL || strm->state == Z_NULL || 673 flush > Z_BLOCK || flush < 0) { 674 return Z_STREAM_ERROR; 675 } 676 s = strm->state; 677 678 if (strm->next_out == Z_NULL || 679 (strm->next_in == Z_NULL && strm->avail_in != 0) || 680 (s->status == FINISH_STATE && flush != Z_FINISH)) { 681 ERR_RETURN(strm, Z_STREAM_ERROR); 682 } 683 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 684 685 s->strm = strm; /* just in case */ 686 old_flush = s->last_flush; 687 s->last_flush = flush; 688 689 /* Write the header */ 690 if (s->status == INIT_STATE) { 691 #ifdef GZIP 692 if (s->wrap == 2) { 693 strm->adler = crc32(0L, Z_NULL, 0); 694 put_byte(s, 31); 695 put_byte(s, 139); 696 put_byte(s, 8); 697 if (s->gzhead == Z_NULL) { 698 put_byte(s, 0); 699 put_byte(s, 0); 700 put_byte(s, 0); 701 put_byte(s, 0); 702 put_byte(s, 0); 703 put_byte(s, s->level == 9 ? 2 : 704 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 705 4 : 0)); 706 put_byte(s, OS_CODE); 707 s->status = BUSY_STATE; 708 } 709 else { 710 put_byte(s, (s->gzhead->text ? 1 : 0) + 711 (s->gzhead->hcrc ? 2 : 0) + 712 (s->gzhead->extra == Z_NULL ? 0 : 4) + 713 (s->gzhead->name == Z_NULL ? 0 : 8) + 714 (s->gzhead->comment == Z_NULL ? 0 : 16) 715 ); 716 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 717 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 718 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 719 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 720 put_byte(s, s->level == 9 ? 2 : 721 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 722 4 : 0)); 723 put_byte(s, s->gzhead->os & 0xff); 724 if (s->gzhead->extra != Z_NULL) { 725 put_byte(s, s->gzhead->extra_len & 0xff); 726 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 727 } 728 if (s->gzhead->hcrc) 729 strm->adler = crc32(strm->adler, s->pending_buf, 730 s->pending); 731 s->gzindex = 0; 732 s->status = EXTRA_STATE; 733 } 734 } 735 else 736 #endif 737 { 738 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; 739 uInt level_flags; 740 741 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 742 level_flags = 0; 743 else if (s->level < 6) 744 level_flags = 1; 745 else if (s->level == 6) 746 level_flags = 2; 747 else 748 level_flags = 3; 749 header |= (level_flags << 6); 750 if (s->strstart != 0) header |= PRESET_DICT; 751 header += 31 - (header % 31); 752 753 s->status = BUSY_STATE; 754 putShortMSB(s, header); 755 756 /* Save the adler32 of the preset dictionary: */ 757 if (s->strstart != 0) { 758 putShortMSB(s, (uInt)(strm->adler >> 16)); 759 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 760 } 761 strm->adler = adler32(0L, Z_NULL, 0); 762 } 763 } 764 #ifdef GZIP 765 if (s->status == EXTRA_STATE) { 766 if (s->gzhead->extra != Z_NULL) { 767 uInt beg = s->pending; /* start of bytes to update crc */ 768 769 while (s->gzindex < (s->gzhead->extra_len & 0xffff)) { 770 if (s->pending == s->pending_buf_size) { 771 if (s->gzhead->hcrc && s->pending > beg) 772 strm->adler = crc32(strm->adler, s->pending_buf + beg, 773 s->pending - beg); 774 flush_pending(strm); 775 beg = s->pending; 776 if (s->pending == s->pending_buf_size) 777 break; 778 } 779 put_byte(s, s->gzhead->extra[s->gzindex]); 780 s->gzindex++; 781 } 782 if (s->gzhead->hcrc && s->pending > beg) 783 strm->adler = crc32(strm->adler, s->pending_buf + beg, 784 s->pending - beg); 785 if (s->gzindex == s->gzhead->extra_len) { 786 s->gzindex = 0; 787 s->status = NAME_STATE; 788 } 789 } 790 else 791 s->status = NAME_STATE; 792 } 793 if (s->status == NAME_STATE) { 794 if (s->gzhead->name != Z_NULL) { 795 uInt beg = s->pending; /* start of bytes to update crc */ 796 int val; 797 798 do { 799 if (s->pending == s->pending_buf_size) { 800 if (s->gzhead->hcrc && s->pending > beg) 801 strm->adler = crc32(strm->adler, s->pending_buf + beg, 802 s->pending - beg); 803 flush_pending(strm); 804 beg = s->pending; 805 if (s->pending == s->pending_buf_size) { 806 val = 1; 807 break; 808 } 809 } 810 val = s->gzhead->name[s->gzindex++]; 811 put_byte(s, val); 812 } while (val != 0); 813 if (s->gzhead->hcrc && s->pending > beg) 814 strm->adler = crc32(strm->adler, s->pending_buf + beg, 815 s->pending - beg); 816 if (val == 0) { 817 s->gzindex = 0; 818 s->status = COMMENT_STATE; 819 } 820 } 821 else 822 s->status = COMMENT_STATE; 823 } 824 if (s->status == COMMENT_STATE) { 825 if (s->gzhead->comment != Z_NULL) { 826 uInt beg = s->pending; /* start of bytes to update crc */ 827 int val; 828 829 do { 830 if (s->pending == s->pending_buf_size) { 831 if (s->gzhead->hcrc && s->pending > beg) 832 strm->adler = crc32(strm->adler, s->pending_buf + beg, 833 s->pending - beg); 834 flush_pending(strm); 835 beg = s->pending; 836 if (s->pending == s->pending_buf_size) { 837 val = 1; 838 break; 839 } 840 } 841 val = s->gzhead->comment[s->gzindex++]; 842 put_byte(s, val); 843 } while (val != 0); 844 if (s->gzhead->hcrc && s->pending > beg) 845 strm->adler = crc32(strm->adler, s->pending_buf + beg, 846 s->pending - beg); 847 if (val == 0) 848 s->status = HCRC_STATE; 849 } 850 else 851 s->status = HCRC_STATE; 852 } 853 if (s->status == HCRC_STATE) { 854 if (s->gzhead->hcrc) { 855 if (s->pending + 2 > s->pending_buf_size) 856 flush_pending(strm); 857 if (s->pending + 2 <= s->pending_buf_size) { 858 put_byte(s, (Byte)(strm->adler & 0xff)); 859 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 860 strm->adler = crc32(0L, Z_NULL, 0); 861 s->status = BUSY_STATE; 862 } 863 } 864 else 865 s->status = BUSY_STATE; 866 } 867 #endif 868 869 /* Flush as much pending output as possible */ 870 if (s->pending != 0) { 871 flush_pending(strm); 872 if (strm->avail_out == 0) { 873 /* Since avail_out is 0, deflate will be called again with 874 * more output space, but possibly with both pending and 875 * avail_in equal to zero. There won't be anything to do, 876 * but this is not an error situation so make sure we 877 * return OK instead of BUF_ERROR at next call of deflate: 878 */ 879 s->last_flush = -1; 880 return Z_OK; 881 } 882 883 /* Make sure there is something to do and avoid duplicate consecutive 884 * flushes. For repeated and useless calls with Z_FINISH, we keep 885 * returning Z_STREAM_END instead of Z_BUF_ERROR. 886 */ 887 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 888 flush != Z_FINISH) { 889 ERR_RETURN(strm, Z_BUF_ERROR); 890 } 891 892 /* User must not provide more input after the first FINISH: */ 893 if (s->status == FINISH_STATE && strm->avail_in != 0) { 894 ERR_RETURN(strm, Z_BUF_ERROR); 895 } 896 897 /* Start a new block or continue the current one. 898 */ 899 if (strm->avail_in != 0 || s->lookahead != 0 || 900 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 901 block_state bstate; 902 903 bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 904 (s->strategy == Z_RLE ? deflate_rle(s, flush) : 905 (*(configuration_table[s->level].func))(s, flush)); 906 907 if (bstate == finish_started || bstate == finish_done) { 908 s->status = FINISH_STATE; 909 } 910 if (bstate == need_more || bstate == finish_started) { 911 if (strm->avail_out == 0) { 912 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 913 } 914 return Z_OK; 915 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 916 * of deflate should use the same flush parameter to make sure 917 * that the flush is complete. So we don't have to output an 918 * empty block here, this will be done at next call. This also 919 * ensures that for a very small output buffer, we emit at most 920 * one empty block. 921 */ 922 } 923 if (bstate == block_done) { 924 if (flush == Z_PARTIAL_FLUSH) { 925 _tr_align(s); 926 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 927 _tr_stored_block(s, (char*)0, 0L, 0); 928 /* For a full flush, this empty block will be recognized 929 * as a special marker by inflate_sync(). 930 */ 931 if (flush == Z_FULL_FLUSH) { 932 CLEAR_HASH(s); /* forget history */ 933 if (s->lookahead == 0) { 934 s->strstart = 0; 935 s->block_start = 0L; 936 s->insert = 0; 937 } 938 } 939 } 940 flush_pending(strm); 941 if (strm->avail_out == 0) { 942 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 943 return Z_OK; 944 } 945 } 946 } 947 Assert(strm->avail_out > 0, "bug2"); 948 949 if (flush != Z_FINISH) return Z_OK; 950 if (s->wrap <= 0) return Z_STREAM_END; 951 952 /* Write the trailer */ 953 #ifdef GZIP 954 if (s->wrap == 2) { 955 put_byte(s, (Byte)(strm->adler & 0xff)); 956 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 957 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 958 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 959 put_byte(s, (Byte)(strm->total_in & 0xff)); 960 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 961 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 962 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 963 } 964 else 965 #endif 966 { 967 putShortMSB(s, (uInt)(strm->adler >> 16)); 968 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 969 } 970 flush_pending(strm); 971 /* If avail_out is zero, the application will call deflate again 972 * to flush the rest. 973 */ 974 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 975 return s->pending != 0 ? Z_OK : Z_STREAM_END; 976 } 977 978 /* ========================================================================= */ 979 int ZEXPORT deflateEnd (strm) 980 z_streamp strm; 981 { 982 int status; 983 984 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 985 986 status = strm->state->status; 987 if (status != INIT_STATE && 988 status != EXTRA_STATE && 989 status != NAME_STATE && 990 status != COMMENT_STATE && 991 status != HCRC_STATE && 992 status != BUSY_STATE && 993 status != FINISH_STATE) { 994 return Z_STREAM_ERROR; 995 } 996 997 /* Deallocate in reverse order of allocations: */ 998 TRY_FREE(strm, strm->state->pending_buf); 999 TRY_FREE(strm, strm->state->head); 1000 TRY_FREE(strm, strm->state->prev); 1001 TRY_FREE(strm, strm->state->window); 1002 1003 ZFREE(strm, strm->state); 1004 strm->state = Z_NULL; 1005 1006 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1007 } 1008 1009 /* ========================================================================= 1010 * Copy the source state to the destination state. 1011 * To simplify the source, this is not supported for 16-bit MSDOS (which 1012 * doesn't have enough memory anyway to duplicate compression states). 1013 */ 1014 int ZEXPORT deflateCopy (dest, source) 1015 z_streamp dest; 1016 z_streamp source; 1017 { 1018 #ifdef MAXSEG_64K 1019 return Z_STREAM_ERROR; 1020 #else 1021 deflate_state *ds; 1022 deflate_state *ss; 1023 ushf *overlay; 1024 1025 1026 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) { 1027 return Z_STREAM_ERROR; 1028 } 1029 1030 ss = source->state; 1031 1032 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream)); 1033 1034 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1035 if (ds == Z_NULL) return Z_MEM_ERROR; 1036 dest->state = (struct internal_state FAR *) ds; 1037 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state)); 1038 ds->strm = dest; 1039 1040 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1041 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1042 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1043 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); 1044 ds->pending_buf = (uchf *) overlay; 1045 1046 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1047 ds->pending_buf == Z_NULL) { 1048 deflateEnd (dest); 1049 return Z_MEM_ERROR; 1050 } 1051 /* following zmemcpy do not work for 16-bit MSDOS */ 1052 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1053 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos)); 1054 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos)); 1055 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); 1056 1057 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1058 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); 1059 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; 1060 1061 ds->l_desc.dyn_tree = ds->dyn_ltree; 1062 ds->d_desc.dyn_tree = ds->dyn_dtree; 1063 ds->bl_desc.dyn_tree = ds->bl_tree; 1064 1065 return Z_OK; 1066 #endif /* MAXSEG_64K */ 1067 } 1068 1069 /* =========================================================================== 1070 * Read a new buffer from the current input stream, update the adler32 1071 * and total number of bytes read. All deflate() input goes through 1072 * this function so some applications may wish to modify it to avoid 1073 * allocating a large strm->next_in buffer and copying from it. 1074 * (See also flush_pending()). 1075 */ 1076 local int read_buf(strm, buf, size) 1077 z_streamp strm; 1078 Bytef *buf; 1079 unsigned size; 1080 { 1081 unsigned len = strm->avail_in; 1082 1083 if (len > size) len = size; 1084 if (len == 0) return 0; 1085 1086 strm->avail_in -= len; 1087 1088 zmemcpy(buf, strm->next_in, len); 1089 if (strm->state->wrap == 1) { 1090 strm->adler = adler32(strm->adler, buf, len); 1091 } 1092 #ifdef GZIP 1093 else if (strm->state->wrap == 2) { 1094 strm->adler = crc32(strm->adler, buf, len); 1095 } 1096 #endif 1097 strm->next_in += len; 1098 strm->total_in += len; 1099 1100 return (int)len; 1101 } 1102 1103 /* =========================================================================== 1104 * Initialize the "longest match" routines for a new zlib stream 1105 */ 1106 local void lm_init (s) 1107 deflate_state *s; 1108 { 1109 s->window_size = (ulg)2L*s->w_size; 1110 1111 CLEAR_HASH(s); 1112 1113 /* Set the default configuration parameters: 1114 */ 1115 s->max_lazy_match = configuration_table[s->level].max_lazy; 1116 s->good_match = configuration_table[s->level].good_length; 1117 s->nice_match = configuration_table[s->level].nice_length; 1118 s->max_chain_length = configuration_table[s->level].max_chain; 1119 1120 s->strstart = 0; 1121 s->block_start = 0L; 1122 s->lookahead = 0; 1123 s->insert = 0; 1124 s->match_length = s->prev_length = MIN_MATCH-1; 1125 s->match_available = 0; 1126 s->ins_h = 0; 1127 #ifndef FASTEST 1128 #ifdef ASMV 1129 match_init(); /* initialize the asm code */ 1130 #endif 1131 #endif 1132 } 1133 1134 #ifndef FASTEST 1135 /* =========================================================================== 1136 * Set match_start to the longest match starting at the given string and 1137 * return its length. Matches shorter or equal to prev_length are discarded, 1138 * in which case the result is equal to prev_length and match_start is 1139 * garbage. 1140 * IN assertions: cur_match is the head of the hash chain for the current 1141 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1142 * OUT assertion: the match length is not greater than s->lookahead. 1143 */ 1144 #ifndef ASMV 1145 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or 1146 * match.S. The code will be functionally equivalent. 1147 */ 1148 local uInt longest_match(s, cur_match) 1149 deflate_state *s; 1150 IPos cur_match; /* current match */ 1151 { 1152 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1153 register Bytef *scan = s->window + s->strstart; /* current string */ 1154 register Bytef *match; /* matched string */ 1155 register int len; /* length of current match */ 1156 int best_len = s->prev_length; /* best match length so far */ 1157 int nice_match = s->nice_match; /* stop if match long enough */ 1158 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1159 s->strstart - (IPos)MAX_DIST(s) : NIL; 1160 /* Stop when cur_match becomes <= limit. To simplify the code, 1161 * we prevent matches with the string of window index 0. 1162 */ 1163 Posf *prev = s->prev; 1164 uInt wmask = s->w_mask; 1165 1166 #ifdef UNALIGNED_OK 1167 /* Compare two bytes at a time. Note: this is not always beneficial. 1168 * Try with and without -DUNALIGNED_OK to check. 1169 */ 1170 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1171 register ush scan_start = *(ushf*)scan; 1172 register ush scan_end = *(ushf*)(scan+best_len-1); 1173 #else 1174 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1175 register Byte scan_end1 = scan[best_len-1]; 1176 register Byte scan_end = scan[best_len]; 1177 #endif 1178 1179 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1180 * It is easy to get rid of this optimization if necessary. 1181 */ 1182 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1183 1184 /* Do not waste too much time if we already have a good match: */ 1185 if (s->prev_length >= s->good_match) { 1186 chain_length >>= 2; 1187 } 1188 /* Do not look for matches beyond the end of the input. This is necessary 1189 * to make deflate deterministic. 1190 */ 1191 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; 1192 1193 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1194 1195 do { 1196 Assert(cur_match < s->strstart, "no future"); 1197 match = s->window + cur_match; 1198 1199 /* Skip to next match if the match length cannot increase 1200 * or if the match length is less than 2. Note that the checks below 1201 * for insufficient lookahead only occur occasionally for performance 1202 * reasons. Therefore uninitialized memory will be accessed, and 1203 * conditional jumps will be made that depend on those values. 1204 * However the length of the match is limited to the lookahead, so 1205 * the output of deflate is not affected by the uninitialized values. 1206 */ 1207 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1208 /* This code assumes sizeof(unsigned short) == 2. Do not use 1209 * UNALIGNED_OK if your compiler uses a different size. 1210 */ 1211 if (*(ushf*)(match+best_len-1) != scan_end || 1212 *(ushf*)match != scan_start) continue; 1213 1214 /* It is not necessary to compare scan[2] and match[2] since they are 1215 * always equal when the other bytes match, given that the hash keys 1216 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1217 * strstart+3, +5, ... up to strstart+257. We check for insufficient 1218 * lookahead only every 4th comparison; the 128th check will be made 1219 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is 1220 * necessary to put more guard bytes at the end of the window, or 1221 * to check more often for insufficient lookahead. 1222 */ 1223 Assert(scan[2] == match[2], "scan[2]?"); 1224 scan++, match++; 1225 do { 1226 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1227 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1228 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1229 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1230 scan < strend); 1231 /* The funny "do {}" generates better code on most compilers */ 1232 1233 /* Here, scan <= window+strstart+257 */ 1234 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1235 if (*scan == *match) scan++; 1236 1237 len = (MAX_MATCH - 1) - (int)(strend-scan); 1238 scan = strend - (MAX_MATCH-1); 1239 1240 #else /* UNALIGNED_OK */ 1241 1242 if (match[best_len] != scan_end || 1243 match[best_len-1] != scan_end1 || 1244 *match != *scan || 1245 *++match != scan[1]) continue; 1246 1247 /* The check at best_len-1 can be removed because it will be made 1248 * again later. (This heuristic is not always a win.) 1249 * It is not necessary to compare scan[2] and match[2] since they 1250 * are always equal when the other bytes match, given that 1251 * the hash keys are equal and that HASH_BITS >= 8. 1252 */ 1253 scan += 2, match++; 1254 Assert(*scan == *match, "match[2]?"); 1255 1256 /* We check for insufficient lookahead only every 8th comparison; 1257 * the 256th check will be made at strstart+258. 1258 */ 1259 do { 1260 } while (*++scan == *++match && *++scan == *++match && 1261 *++scan == *++match && *++scan == *++match && 1262 *++scan == *++match && *++scan == *++match && 1263 *++scan == *++match && *++scan == *++match && 1264 scan < strend); 1265 1266 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1267 1268 len = MAX_MATCH - (int)(strend - scan); 1269 scan = strend - MAX_MATCH; 1270 1271 #endif /* UNALIGNED_OK */ 1272 1273 if (len > best_len) { 1274 s->match_start = cur_match; 1275 best_len = len; 1276 if (len >= nice_match) break; 1277 #ifdef UNALIGNED_OK 1278 scan_end = *(ushf*)(scan+best_len-1); 1279 #else 1280 scan_end1 = scan[best_len-1]; 1281 scan_end = scan[best_len]; 1282 #endif 1283 } 1284 } while ((cur_match = prev[cur_match & wmask]) > limit 1285 && --chain_length != 0); 1286 1287 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1288 return s->lookahead; 1289 } 1290 #endif /* ASMV */ 1291 1292 #else /* FASTEST */ 1293 1294 /* --------------------------------------------------------------------------- 1295 * Optimized version for FASTEST only 1296 */ 1297 local uInt longest_match(s, cur_match) 1298 deflate_state *s; 1299 IPos cur_match; /* current match */ 1300 { 1301 register Bytef *scan = s->window + s->strstart; /* current string */ 1302 register Bytef *match; /* matched string */ 1303 register int len; /* length of current match */ 1304 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1305 1306 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1307 * It is easy to get rid of this optimization if necessary. 1308 */ 1309 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1310 1311 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1312 1313 Assert(cur_match < s->strstart, "no future"); 1314 1315 match = s->window + cur_match; 1316 1317 /* Return failure if the match length is less than 2: 1318 */ 1319 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1320 1321 /* The check at best_len-1 can be removed because it will be made 1322 * again later. (This heuristic is not always a win.) 1323 * It is not necessary to compare scan[2] and match[2] since they 1324 * are always equal when the other bytes match, given that 1325 * the hash keys are equal and that HASH_BITS >= 8. 1326 */ 1327 scan += 2, match += 2; 1328 Assert(*scan == *match, "match[2]?"); 1329 1330 /* We check for insufficient lookahead only every 8th comparison; 1331 * the 256th check will be made at strstart+258. 1332 */ 1333 do { 1334 } while (*++scan == *++match && *++scan == *++match && 1335 *++scan == *++match && *++scan == *++match && 1336 *++scan == *++match && *++scan == *++match && 1337 *++scan == *++match && *++scan == *++match && 1338 scan < strend); 1339 1340 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1341 1342 len = MAX_MATCH - (int)(strend - scan); 1343 1344 if (len < MIN_MATCH) return MIN_MATCH - 1; 1345 1346 s->match_start = cur_match; 1347 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1348 } 1349 1350 #endif /* FASTEST */ 1351 1352 #ifdef DEBUG 1353 /* =========================================================================== 1354 * Check that the match at match_start is indeed a match. 1355 */ 1356 local void check_match(s, start, match, length) 1357 deflate_state *s; 1358 IPos start, match; 1359 int length; 1360 { 1361 /* check that the match is indeed a match */ 1362 if (zmemcmp(s->window + match, 1363 s->window + start, length) != EQUAL) { 1364 fprintf(stderr, " start %u, match %u, length %d\n", 1365 start, match, length); 1366 do { 1367 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); 1368 } while (--length != 0); 1369 z_error("invalid match"); 1370 } 1371 if (z_verbose > 1) { 1372 fprintf(stderr,"\\[%d,%d]", start-match, length); 1373 do { putc(s->window[start++], stderr); } while (--length != 0); 1374 } 1375 } 1376 #else 1377 # define check_match(s, start, match, length) 1378 #endif /* DEBUG */ 1379 1380 /* =========================================================================== 1381 * Fill the window when the lookahead becomes insufficient. 1382 * Updates strstart and lookahead. 1383 * 1384 * IN assertion: lookahead < MIN_LOOKAHEAD 1385 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 1386 * At least one byte has been read, or avail_in == 0; reads are 1387 * performed for at least two bytes (required for the zip translate_eol 1388 * option -- not supported here). 1389 */ 1390 local void fill_window(s) 1391 deflate_state *s; 1392 { 1393 register unsigned n, m; 1394 register Posf *p; 1395 unsigned more; /* Amount of free space at the end of the window. */ 1396 uInt wsize = s->w_size; 1397 1398 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); 1399 1400 do { 1401 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 1402 1403 /* Deal with !@#$% 64K limit: */ 1404 if (sizeof(int) <= 2) { 1405 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 1406 more = wsize; 1407 1408 } else if (more == (unsigned)(-1)) { 1409 /* Very unlikely, but possible on 16 bit machine if 1410 * strstart == 0 && lookahead == 1 (input done a byte at time) 1411 */ 1412 more--; 1413 } 1414 } 1415 1416 /* If the window is almost full and there is insufficient lookahead, 1417 * move the upper half to the lower one to make room in the upper half. 1418 */ 1419 if (s->strstart >= wsize+MAX_DIST(s)) { 1420 1421 zmemcpy(s->window, s->window+wsize, (unsigned)wsize); 1422 s->match_start -= wsize; 1423 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 1424 s->block_start -= (long) wsize; 1425 1426 /* Slide the hash table (could be avoided with 32 bit values 1427 at the expense of memory usage). We slide even when level == 0 1428 to keep the hash table consistent if we switch back to level > 0 1429 later. (Using level 0 permanently is not an optimal usage of 1430 zlib, so we don't care about this pathological case.) 1431 */ 1432 n = s->hash_size; 1433 p = &s->head[n]; 1434 do { 1435 m = *--p; 1436 *p = (Pos)(m >= wsize ? m-wsize : NIL); 1437 } while (--n); 1438 1439 n = wsize; 1440 #ifndef FASTEST 1441 p = &s->prev[n]; 1442 do { 1443 m = *--p; 1444 *p = (Pos)(m >= wsize ? m-wsize : NIL); 1445 /* If n is not on any hash chain, prev[n] is garbage but 1446 * its value will never be used. 1447 */ 1448 } while (--n); 1449 #endif 1450 more += wsize; 1451 } 1452 if (s->strm->avail_in == 0) break; 1453 1454 /* If there was no sliding: 1455 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 1456 * more == window_size - lookahead - strstart 1457 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 1458 * => more >= window_size - 2*WSIZE + 2 1459 * In the BIG_MEM or MMAP case (not yet supported), 1460 * window_size == input_size + MIN_LOOKAHEAD && 1461 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 1462 * Otherwise, window_size == 2*WSIZE so more >= 2. 1463 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 1464 */ 1465 Assert(more >= 2, "more < 2"); 1466 1467 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 1468 s->lookahead += n; 1469 1470 /* Initialize the hash value now that we have some input: */ 1471 if (s->lookahead + s->insert >= MIN_MATCH) { 1472 uInt str = s->strstart - s->insert; 1473 s->ins_h = s->window[str]; 1474 UPDATE_HASH(s, s->ins_h, s->window[str + 1]); 1475 #if MIN_MATCH != 3 1476 Call UPDATE_HASH() MIN_MATCH-3 more times 1477 #endif 1478 while (s->insert) { 1479 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 1480 #ifndef FASTEST 1481 s->prev[str & s->w_mask] = s->head[s->ins_h]; 1482 #endif 1483 s->head[s->ins_h] = (Pos)str; 1484 str++; 1485 s->insert--; 1486 if (s->lookahead + s->insert < MIN_MATCH) 1487 break; 1488 } 1489 } 1490 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 1491 * but this is not important since only literal bytes will be emitted. 1492 */ 1493 1494 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 1495 1496 /* If the WIN_INIT bytes after the end of the current data have never been 1497 * written, then zero those bytes in order to avoid memory check reports of 1498 * the use of uninitialized (or uninitialised as Julian writes) bytes by 1499 * the longest match routines. Update the high water mark for the next 1500 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 1501 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 1502 */ 1503 if (s->high_water < s->window_size) { 1504 ulg curr = s->strstart + (ulg)(s->lookahead); 1505 ulg init; 1506 1507 if (s->high_water < curr) { 1508 /* Previous high water mark below current data -- zero WIN_INIT 1509 * bytes or up to end of window, whichever is less. 1510 */ 1511 init = s->window_size - curr; 1512 if (init > WIN_INIT) 1513 init = WIN_INIT; 1514 zmemzero(s->window + curr, (unsigned)init); 1515 s->high_water = curr + init; 1516 } 1517 else if (s->high_water < (ulg)curr + WIN_INIT) { 1518 /* High water mark at or above current data, but below current data 1519 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 1520 * to end of window, whichever is less. 1521 */ 1522 init = (ulg)curr + WIN_INIT - s->high_water; 1523 if (init > s->window_size - s->high_water) 1524 init = s->window_size - s->high_water; 1525 zmemzero(s->window + s->high_water, (unsigned)init); 1526 s->high_water += init; 1527 } 1528 } 1529 1530 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1531 "not enough room for search"); 1532 } 1533 1534 /* =========================================================================== 1535 * Flush the current block, with given end-of-file flag. 1536 * IN assertion: strstart is set to the end of the current match. 1537 */ 1538 #define FLUSH_BLOCK_ONLY(s, last) { \ 1539 _tr_flush_block(s, (s->block_start >= 0L ? \ 1540 (charf *)&s->window[(unsigned)s->block_start] : \ 1541 (charf *)Z_NULL), \ 1542 (ulg)((long)s->strstart - s->block_start), \ 1543 (last)); \ 1544 s->block_start = s->strstart; \ 1545 flush_pending(s->strm); \ 1546 Tracev((stderr,"[FLUSH]")); \ 1547 } 1548 1549 /* Same but force premature exit if necessary. */ 1550 #define FLUSH_BLOCK(s, last) { \ 1551 FLUSH_BLOCK_ONLY(s, last); \ 1552 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1553 } 1554 1555 /* =========================================================================== 1556 * Copy without compression as much as possible from the input stream, return 1557 * the current block state. 1558 * This function does not insert new strings in the dictionary since 1559 * uncompressible data is probably not useful. This function is used 1560 * only for the level=0 compression option. 1561 * NOTE: this function should be optimized to avoid extra copying from 1562 * window to pending_buf. 1563 */ 1564 local block_state deflate_stored(s, flush) 1565 deflate_state *s; 1566 int flush; 1567 { 1568 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited 1569 * to pending_buf_size, and each stored block has a 5 byte header: 1570 */ 1571 ulg max_block_size = 0xffff; 1572 ulg max_start; 1573 1574 if (max_block_size > s->pending_buf_size - 5) { 1575 max_block_size = s->pending_buf_size - 5; 1576 } 1577 1578 /* Copy as much as possible from input to output: */ 1579 for (;;) { 1580 /* Fill the window as much as possible: */ 1581 if (s->lookahead <= 1) { 1582 1583 Assert(s->strstart < s->w_size+MAX_DIST(s) || 1584 s->block_start >= (long)s->w_size, "slide too late"); 1585 1586 fill_window(s); 1587 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more; 1588 1589 if (s->lookahead == 0) break; /* flush the current block */ 1590 } 1591 Assert(s->block_start >= 0L, "block gone"); 1592 1593 s->strstart += s->lookahead; 1594 s->lookahead = 0; 1595 1596 /* Emit a stored block if pending_buf will be full: */ 1597 max_start = s->block_start + max_block_size; 1598 if (s->strstart == 0 || (ulg)s->strstart >= max_start) { 1599 /* strstart == 0 is possible when wraparound on 16-bit machine */ 1600 s->lookahead = (uInt)(s->strstart - max_start); 1601 s->strstart = (uInt)max_start; 1602 FLUSH_BLOCK(s, 0); 1603 } 1604 /* Flush if we may have to slide, otherwise block_start may become 1605 * negative and the data will be gone: 1606 */ 1607 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) { 1608 FLUSH_BLOCK(s, 0); 1609 } 1610 } 1611 s->insert = 0; 1612 if (flush == Z_FINISH) { 1613 FLUSH_BLOCK(s, 1); 1614 return finish_done; 1615 } 1616 if ((long)s->strstart > s->block_start) 1617 FLUSH_BLOCK(s, 0); 1618 return block_done; 1619 } 1620 1621 /* =========================================================================== 1622 * Compress as much as possible from the input stream, return the current 1623 * block state. 1624 * This function does not perform lazy evaluation of matches and inserts 1625 * new strings in the dictionary only for unmatched strings or for short 1626 * matches. It is used only for the fast compression options. 1627 */ 1628 local block_state deflate_fast(s, flush) 1629 deflate_state *s; 1630 int flush; 1631 { 1632 IPos hash_head; /* head of the hash chain */ 1633 int bflush; /* set if current block must be flushed */ 1634 1635 for (;;) { 1636 /* Make sure that we always have enough lookahead, except 1637 * at the end of the input file. We need MAX_MATCH bytes 1638 * for the next match, plus MIN_MATCH bytes to insert the 1639 * string following the next match. 1640 */ 1641 if (s->lookahead < MIN_LOOKAHEAD) { 1642 fill_window(s); 1643 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1644 return need_more; 1645 } 1646 if (s->lookahead == 0) break; /* flush the current block */ 1647 } 1648 1649 /* Insert the string window[strstart .. strstart+2] in the 1650 * dictionary, and set hash_head to the head of the hash chain: 1651 */ 1652 hash_head = NIL; 1653 if (s->lookahead >= MIN_MATCH) { 1654 INSERT_STRING(s, s->strstart, hash_head); 1655 } 1656 1657 /* Find the longest match, discarding those <= prev_length. 1658 * At this point we have always match_length < MIN_MATCH 1659 */ 1660 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1661 /* To simplify the code, we prevent matches with the string 1662 * of window index 0 (in particular we have to avoid a match 1663 * of the string with itself at the start of the input file). 1664 */ 1665 s->match_length = longest_match (s, hash_head); 1666 /* longest_match() sets match_start */ 1667 } 1668 if (s->match_length >= MIN_MATCH) { 1669 check_match(s, s->strstart, s->match_start, s->match_length); 1670 1671 _tr_tally_dist(s, s->strstart - s->match_start, 1672 s->match_length - MIN_MATCH, bflush); 1673 1674 s->lookahead -= s->match_length; 1675 1676 /* Insert new strings in the hash table only if the match length 1677 * is not too large. This saves time but degrades compression. 1678 */ 1679 #ifndef FASTEST 1680 if (s->match_length <= s->max_insert_length && 1681 s->lookahead >= MIN_MATCH) { 1682 s->match_length--; /* string at strstart already in table */ 1683 do { 1684 s->strstart++; 1685 INSERT_STRING(s, s->strstart, hash_head); 1686 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1687 * always MIN_MATCH bytes ahead. 1688 */ 1689 } while (--s->match_length != 0); 1690 s->strstart++; 1691 } else 1692 #endif 1693 { 1694 s->strstart += s->match_length; 1695 s->match_length = 0; 1696 s->ins_h = s->window[s->strstart]; 1697 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); 1698 #if MIN_MATCH != 3 1699 Call UPDATE_HASH() MIN_MATCH-3 more times 1700 #endif 1701 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1702 * matter since it will be recomputed at next deflate call. 1703 */ 1704 } 1705 } else { 1706 /* No match, output a literal byte */ 1707 Tracevv((stderr,"%c", s->window[s->strstart])); 1708 _tr_tally_lit (s, s->window[s->strstart], bflush); 1709 s->lookahead--; 1710 s->strstart++; 1711 } 1712 if (bflush) FLUSH_BLOCK(s, 0); 1713 } 1714 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1715 if (flush == Z_FINISH) { 1716 FLUSH_BLOCK(s, 1); 1717 return finish_done; 1718 } 1719 if (s->last_lit) 1720 FLUSH_BLOCK(s, 0); 1721 return block_done; 1722 } 1723 1724 #ifndef FASTEST 1725 /* =========================================================================== 1726 * Same as above, but achieves better compression. We use a lazy 1727 * evaluation for matches: a match is finally adopted only if there is 1728 * no better match at the next window position. 1729 */ 1730 local block_state deflate_slow(s, flush) 1731 deflate_state *s; 1732 int flush; 1733 { 1734 IPos hash_head; /* head of hash chain */ 1735 int bflush; /* set if current block must be flushed */ 1736 1737 /* Process the input block. */ 1738 for (;;) { 1739 /* Make sure that we always have enough lookahead, except 1740 * at the end of the input file. We need MAX_MATCH bytes 1741 * for the next match, plus MIN_MATCH bytes to insert the 1742 * string following the next match. 1743 */ 1744 if (s->lookahead < MIN_LOOKAHEAD) { 1745 fill_window(s); 1746 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1747 return need_more; 1748 } 1749 if (s->lookahead == 0) break; /* flush the current block */ 1750 } 1751 1752 /* Insert the string window[strstart .. strstart+2] in the 1753 * dictionary, and set hash_head to the head of the hash chain: 1754 */ 1755 hash_head = NIL; 1756 if (s->lookahead >= MIN_MATCH) { 1757 INSERT_STRING(s, s->strstart, hash_head); 1758 } 1759 1760 /* Find the longest match, discarding those <= prev_length. 1761 */ 1762 s->prev_length = s->match_length, s->prev_match = s->match_start; 1763 s->match_length = MIN_MATCH-1; 1764 1765 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1766 s->strstart - hash_head <= MAX_DIST(s)) { 1767 /* To simplify the code, we prevent matches with the string 1768 * of window index 0 (in particular we have to avoid a match 1769 * of the string with itself at the start of the input file). 1770 */ 1771 s->match_length = longest_match (s, hash_head); 1772 /* longest_match() sets match_start */ 1773 1774 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1775 #if TOO_FAR <= 32767 1776 || (s->match_length == MIN_MATCH && 1777 s->strstart - s->match_start > TOO_FAR) 1778 #endif 1779 )) { 1780 1781 /* If prev_match is also MIN_MATCH, match_start is garbage 1782 * but we will ignore the current match anyway. 1783 */ 1784 s->match_length = MIN_MATCH-1; 1785 } 1786 } 1787 /* If there was a match at the previous step and the current 1788 * match is not better, output the previous match: 1789 */ 1790 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1791 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1792 /* Do not insert strings in hash table beyond this. */ 1793 1794 check_match(s, s->strstart-1, s->prev_match, s->prev_length); 1795 1796 _tr_tally_dist(s, s->strstart -1 - s->prev_match, 1797 s->prev_length - MIN_MATCH, bflush); 1798 1799 /* Insert in hash table all strings up to the end of the match. 1800 * strstart-1 and strstart are already inserted. If there is not 1801 * enough lookahead, the last two strings are not inserted in 1802 * the hash table. 1803 */ 1804 s->lookahead -= s->prev_length-1; 1805 s->prev_length -= 2; 1806 do { 1807 if (++s->strstart <= max_insert) { 1808 INSERT_STRING(s, s->strstart, hash_head); 1809 } 1810 } while (--s->prev_length != 0); 1811 s->match_available = 0; 1812 s->match_length = MIN_MATCH-1; 1813 s->strstart++; 1814 1815 if (bflush) FLUSH_BLOCK(s, 0); 1816 1817 } else if (s->match_available) { 1818 /* If there was no match at the previous position, output a 1819 * single literal. If there was a match but the current match 1820 * is longer, truncate the previous match to a single literal. 1821 */ 1822 Tracevv((stderr,"%c", s->window[s->strstart-1])); 1823 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 1824 if (bflush) { 1825 FLUSH_BLOCK_ONLY(s, 0); 1826 } 1827 s->strstart++; 1828 s->lookahead--; 1829 if (s->strm->avail_out == 0) return need_more; 1830 } else { 1831 /* There is no previous match to compare with, wait for 1832 * the next step to decide. 1833 */ 1834 s->match_available = 1; 1835 s->strstart++; 1836 s->lookahead--; 1837 } 1838 } 1839 Assert (flush != Z_NO_FLUSH, "no flush?"); 1840 if (s->match_available) { 1841 Tracevv((stderr,"%c", s->window[s->strstart-1])); 1842 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 1843 s->match_available = 0; 1844 } 1845 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1846 if (flush == Z_FINISH) { 1847 FLUSH_BLOCK(s, 1); 1848 return finish_done; 1849 } 1850 if (s->last_lit) 1851 FLUSH_BLOCK(s, 0); 1852 return block_done; 1853 } 1854 #endif /* FASTEST */ 1855 1856 /* =========================================================================== 1857 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 1858 * one. Do not maintain a hash table. (It will be regenerated if this run of 1859 * deflate switches away from Z_RLE.) 1860 */ 1861 local block_state deflate_rle(s, flush) 1862 deflate_state *s; 1863 int flush; 1864 { 1865 int bflush; /* set if current block must be flushed */ 1866 uInt prev; /* byte at distance one to match */ 1867 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 1868 1869 for (;;) { 1870 /* Make sure that we always have enough lookahead, except 1871 * at the end of the input file. We need MAX_MATCH bytes 1872 * for the longest run, plus one for the unrolled loop. 1873 */ 1874 if (s->lookahead <= MAX_MATCH) { 1875 fill_window(s); 1876 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 1877 return need_more; 1878 } 1879 if (s->lookahead == 0) break; /* flush the current block */ 1880 } 1881 1882 /* See how many times the previous byte repeats */ 1883 s->match_length = 0; 1884 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 1885 scan = s->window + s->strstart - 1; 1886 prev = *scan; 1887 if (prev == *++scan && prev == *++scan && prev == *++scan) { 1888 strend = s->window + s->strstart + MAX_MATCH; 1889 do { 1890 } while (prev == *++scan && prev == *++scan && 1891 prev == *++scan && prev == *++scan && 1892 prev == *++scan && prev == *++scan && 1893 prev == *++scan && prev == *++scan && 1894 scan < strend); 1895 s->match_length = MAX_MATCH - (int)(strend - scan); 1896 if (s->match_length > s->lookahead) 1897 s->match_length = s->lookahead; 1898 } 1899 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan"); 1900 } 1901 1902 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 1903 if (s->match_length >= MIN_MATCH) { 1904 check_match(s, s->strstart, s->strstart - 1, s->match_length); 1905 1906 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 1907 1908 s->lookahead -= s->match_length; 1909 s->strstart += s->match_length; 1910 s->match_length = 0; 1911 } else { 1912 /* No match, output a literal byte */ 1913 Tracevv((stderr,"%c", s->window[s->strstart])); 1914 _tr_tally_lit (s, s->window[s->strstart], bflush); 1915 s->lookahead--; 1916 s->strstart++; 1917 } 1918 if (bflush) FLUSH_BLOCK(s, 0); 1919 } 1920 s->insert = 0; 1921 if (flush == Z_FINISH) { 1922 FLUSH_BLOCK(s, 1); 1923 return finish_done; 1924 } 1925 if (s->last_lit) 1926 FLUSH_BLOCK(s, 0); 1927 return block_done; 1928 } 1929 1930 /* =========================================================================== 1931 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 1932 * (It will be regenerated if this run of deflate switches away from Huffman.) 1933 */ 1934 local block_state deflate_huff(s, flush) 1935 deflate_state *s; 1936 int flush; 1937 { 1938 int bflush; /* set if current block must be flushed */ 1939 1940 for (;;) { 1941 /* Make sure that we have a literal to write. */ 1942 if (s->lookahead == 0) { 1943 fill_window(s); 1944 if (s->lookahead == 0) { 1945 if (flush == Z_NO_FLUSH) 1946 return need_more; 1947 break; /* flush the current block */ 1948 } 1949 } 1950 1951 /* Output a literal byte */ 1952 s->match_length = 0; 1953 Tracevv((stderr,"%c", s->window[s->strstart])); 1954 _tr_tally_lit (s, s->window[s->strstart], bflush); 1955 s->lookahead--; 1956 s->strstart++; 1957 if (bflush) FLUSH_BLOCK(s, 0); 1958 } 1959 s->insert = 0; 1960 if (flush == Z_FINISH) { 1961 FLUSH_BLOCK(s, 1); 1962 return finish_done; 1963 } 1964 if (s->last_lit) 1965 FLUSH_BLOCK(s, 0); 1966 return block_done; 1967 } 1968
