1 /* deflate.c -- compress data using the deflation algorithm 2 * Copyright (C) 1995-2022 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 1.2.13 Copyright 1995-2022 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 int deflateStateCheck OF((z_streamp strm)); 77 local void slide_hash OF((deflate_state *s)); 78 local void fill_window OF((deflate_state *s)); 79 local block_state deflate_stored OF((deflate_state *s, int flush)); 80 local block_state deflate_fast OF((deflate_state *s, int flush)); 81 #ifndef FASTEST 82 local block_state deflate_slow OF((deflate_state *s, int flush)); 83 #endif 84 local block_state deflate_rle OF((deflate_state *s, int flush)); 85 local block_state deflate_huff OF((deflate_state *s, int flush)); 86 local void lm_init OF((deflate_state *s)); 87 local void putShortMSB OF((deflate_state *s, uInt b)); 88 local void flush_pending OF((z_streamp strm)); 89 local unsigned read_buf OF((z_streamp strm, Bytef *buf, unsigned size)); 90 local uInt longest_match OF((deflate_state *s, IPos cur_match)); 91 92 #ifdef ZLIB_DEBUG 93 local void check_match OF((deflate_state *s, IPos start, IPos match, 94 int length)); 95 #endif 96 97 /* =========================================================================== 98 * Local data 99 */ 100 101 #define NIL 0 102 /* Tail of hash chains */ 103 104 #ifndef TOO_FAR 105 # define TOO_FAR 4096 106 #endif 107 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ 108 109 /* Values for max_lazy_match, good_match and max_chain_length, depending on 110 * the desired pack level (0..9). The values given below have been tuned to 111 * exclude worst case performance for pathological files. Better values may be 112 * found for specific files. 113 */ 114 typedef struct config_s { 115 ush good_length; /* reduce lazy search above this match length */ 116 ush max_lazy; /* do not perform lazy search above this match length */ 117 ush nice_length; /* quit search above this match length */ 118 ush max_chain; 119 compress_func func; 120 } config; 121 122 #ifdef FASTEST 123 local const config configuration_table[2] = { 124 /* good lazy nice chain */ 125 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 126 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ 127 #else 128 local const config configuration_table[10] = { 129 /* good lazy nice chain */ 130 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 131 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ 132 /* 2 */ {4, 5, 16, 8, deflate_fast}, 133 /* 3 */ {4, 6, 32, 32, deflate_fast}, 134 135 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ 136 /* 5 */ {8, 16, 32, 32, deflate_slow}, 137 /* 6 */ {8, 16, 128, 128, deflate_slow}, 138 /* 7 */ {8, 32, 128, 256, deflate_slow}, 139 /* 8 */ {32, 128, 258, 1024, deflate_slow}, 140 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ 141 #endif 142 143 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 144 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different 145 * meaning. 146 */ 147 148 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */ 149 #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0)) 150 151 /* =========================================================================== 152 * Update a hash value with the given input byte 153 * IN assertion: all calls to UPDATE_HASH are made with consecutive input 154 * characters, so that a running hash key can be computed from the previous 155 * key instead of complete recalculation each time. 156 */ 157 #define UPDATE_HASH(s,h,c) (h = (((h) << s->hash_shift) ^ (c)) & s->hash_mask) 158 159 160 /* =========================================================================== 161 * Insert string str in the dictionary and set match_head to the previous head 162 * of the hash chain (the most recent string with same hash key). Return 163 * the previous length of the hash chain. 164 * If this file is compiled with -DFASTEST, the compression level is forced 165 * to 1, and no hash chains are maintained. 166 * IN assertion: all calls to INSERT_STRING are made with consecutive input 167 * characters and the first MIN_MATCH bytes of str are valid (except for 168 * the last MIN_MATCH-1 bytes of the input file). 169 */ 170 #ifdef FASTEST 171 #define INSERT_STRING(s, str, match_head) \ 172 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 173 match_head = s->head[s->ins_h], \ 174 s->head[s->ins_h] = (Pos)(str)) 175 #else 176 #define INSERT_STRING(s, str, match_head) \ 177 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 178 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ 179 s->head[s->ins_h] = (Pos)(str)) 180 #endif 181 182 /* =========================================================================== 183 * Initialize the hash table (avoiding 64K overflow for 16 bit systems). 184 * prev[] will be initialized on the fly. 185 */ 186 #define CLEAR_HASH(s) \ 187 do { \ 188 s->head[s->hash_size - 1] = NIL; \ 189 zmemzero((Bytef *)s->head, \ 190 (unsigned)(s->hash_size - 1)*sizeof(*s->head)); \ 191 } while (0) 192 193 /* =========================================================================== 194 * Slide the hash table when sliding the window down (could be avoided with 32 195 * bit values at the expense of memory usage). We slide even when level == 0 to 196 * keep the hash table consistent if we switch back to level > 0 later. 197 */ 198 local void slide_hash( 199 deflate_state *s) 200 { 201 unsigned n, m; 202 Posf *p; 203 uInt wsize = s->w_size; 204 205 n = s->hash_size; 206 p = &s->head[n]; 207 do { 208 m = *--p; 209 *p = (Pos)(m >= wsize ? m - wsize : NIL); 210 } while (--n); 211 n = wsize; 212 #ifndef FASTEST 213 p = &s->prev[n]; 214 do { 215 m = *--p; 216 *p = (Pos)(m >= wsize ? m - wsize : NIL); 217 /* If n is not on any hash chain, prev[n] is garbage but 218 * its value will never be used. 219 */ 220 } while (--n); 221 #endif 222 } 223 224 /* ========================================================================= */ 225 int ZEXPORT deflateInit_( 226 z_streamp strm, 227 int level, 228 const char *version, 229 int stream_size) 230 { 231 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, 232 Z_DEFAULT_STRATEGY, version, stream_size); 233 /* To do: ignore strm->next_in if we use it as window */ 234 } 235 236 /* ========================================================================= */ 237 int ZEXPORT deflateInit2_( 238 z_streamp strm, 239 int level, 240 int method, 241 int windowBits, 242 int memLevel, 243 int strategy, 244 const char *version, 245 int stream_size) 246 { 247 deflate_state *s; 248 int wrap = 1; 249 static const char my_version[] = ZLIB_VERSION; 250 251 if (version == Z_NULL || version[0] != my_version[0] || 252 stream_size != sizeof(z_stream)) { 253 return Z_VERSION_ERROR; 254 } 255 if (strm == Z_NULL) return Z_STREAM_ERROR; 256 257 strm->msg = Z_NULL; 258 if (strm->zalloc == (alloc_func)0) { 259 #ifdef Z_SOLO 260 return Z_STREAM_ERROR; 261 #else 262 strm->zalloc = zcalloc; 263 strm->opaque = (voidpf)0; 264 #endif 265 } 266 if (strm->zfree == (free_func)0) 267 #ifdef Z_SOLO 268 return Z_STREAM_ERROR; 269 #else 270 strm->zfree = zcfree; 271 #endif 272 273 #ifdef FASTEST 274 if (level != 0) level = 1; 275 #else 276 if (level == Z_DEFAULT_COMPRESSION) level = 6; 277 #endif 278 279 if (windowBits < 0) { /* suppress zlib wrapper */ 280 wrap = 0; 281 if (windowBits < -15) 282 return Z_STREAM_ERROR; 283 windowBits = -windowBits; 284 } 285 #ifdef GZIP 286 else if (windowBits > 15) { 287 wrap = 2; /* write gzip wrapper instead */ 288 windowBits -= 16; 289 } 290 #endif 291 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 292 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 293 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) { 294 return Z_STREAM_ERROR; 295 } 296 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 297 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 298 if (s == Z_NULL) return Z_MEM_ERROR; 299 strm->state = (struct internal_state FAR *)s; 300 s->strm = strm; 301 s->status = INIT_STATE; /* to pass state test in deflateReset() */ 302 303 s->wrap = wrap; 304 s->gzhead = Z_NULL; 305 s->w_bits = (uInt)windowBits; 306 s->w_size = 1 << s->w_bits; 307 s->w_mask = s->w_size - 1; 308 309 s->hash_bits = (uInt)memLevel + 7; 310 s->hash_size = 1 << s->hash_bits; 311 s->hash_mask = s->hash_size - 1; 312 s->hash_shift = ((s->hash_bits + MIN_MATCH-1) / MIN_MATCH); 313 314 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 315 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 316 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 317 318 s->high_water = 0; /* nothing written to s->window yet */ 319 320 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 321 322 /* We overlay pending_buf and sym_buf. This works since the average size 323 * for length/distance pairs over any compressed block is assured to be 31 324 * bits or less. 325 * 326 * Analysis: The longest fixed codes are a length code of 8 bits plus 5 327 * extra bits, for lengths 131 to 257. The longest fixed distance codes are 328 * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest 329 * possible fixed-codes length/distance pair is then 31 bits total. 330 * 331 * sym_buf starts one-fourth of the way into pending_buf. So there are 332 * three bytes in sym_buf for every four bytes in pending_buf. Each symbol 333 * in sym_buf is three bytes -- two for the distance and one for the 334 * literal/length. As each symbol is consumed, the pointer to the next 335 * sym_buf value to read moves forward three bytes. From that symbol, up to 336 * 31 bits are written to pending_buf. The closest the written pending_buf 337 * bits gets to the next sym_buf symbol to read is just before the last 338 * code is written. At that time, 31*(n - 2) bits have been written, just 339 * after 24*(n - 2) bits have been consumed from sym_buf. sym_buf starts at 340 * 8*n bits into pending_buf. (Note that the symbol buffer fills when n - 1 341 * symbols are written.) The closest the writing gets to what is unread is 342 * then n + 14 bits. Here n is lit_bufsize, which is 16384 by default, and 343 * can range from 128 to 32768. 344 * 345 * Therefore, at a minimum, there are 142 bits of space between what is 346 * written and what is read in the overlain buffers, so the symbols cannot 347 * be overwritten by the compressed data. That space is actually 139 bits, 348 * due to the three-bit fixed-code block header. 349 * 350 * That covers the case where either Z_FIXED is specified, forcing fixed 351 * codes, or when the use of fixed codes is chosen, because that choice 352 * results in a smaller compressed block than dynamic codes. That latter 353 * condition then assures that the above analysis also covers all dynamic 354 * blocks. A dynamic-code block will only be chosen to be emitted if it has 355 * fewer bits than a fixed-code block would for the same set of symbols. 356 * Therefore its average symbol length is assured to be less than 31. So 357 * the compressed data for a dynamic block also cannot overwrite the 358 * symbols from which it is being constructed. 359 */ 360 361 s->pending_buf = (uchf *) ZALLOC(strm, s->lit_bufsize, 4); 362 s->pending_buf_size = (ulg)s->lit_bufsize * 4; 363 364 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 365 s->pending_buf == Z_NULL) { 366 s->status = FINISH_STATE; 367 strm->msg = ERR_MSG(Z_MEM_ERROR); 368 deflateEnd (strm); 369 return Z_MEM_ERROR; 370 } 371 s->sym_buf = s->pending_buf + s->lit_bufsize; 372 s->sym_end = (s->lit_bufsize - 1) * 3; 373 /* We avoid equality with lit_bufsize*3 because of wraparound at 64K 374 * on 16 bit machines and because stored blocks are restricted to 375 * 64K-1 bytes. 376 */ 377 378 s->level = level; 379 s->strategy = strategy; 380 s->method = (Byte)method; 381 382 return deflateReset(strm); 383 } 384 385 /* ========================================================================= 386 * Check for a valid deflate stream state. Return 0 if ok, 1 if not. 387 */ 388 local int deflateStateCheck ( 389 z_streamp strm) 390 { 391 deflate_state *s; 392 if (strm == Z_NULL || 393 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) 394 return 1; 395 s = strm->state; 396 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE && 397 #ifdef GZIP 398 s->status != GZIP_STATE && 399 #endif 400 s->status != EXTRA_STATE && 401 s->status != NAME_STATE && 402 s->status != COMMENT_STATE && 403 s->status != HCRC_STATE && 404 s->status != BUSY_STATE && 405 s->status != FINISH_STATE)) 406 return 1; 407 return 0; 408 } 409 410 /* ========================================================================= */ 411 int ZEXPORT deflateSetDictionary ( 412 z_streamp strm, 413 const Bytef *dictionary, 414 uInt dictLength) 415 { 416 deflate_state *s; 417 uInt str, n; 418 int wrap; 419 unsigned avail; 420 z_const unsigned char *next; 421 422 if (deflateStateCheck(strm) || dictionary == Z_NULL) 423 return Z_STREAM_ERROR; 424 s = strm->state; 425 wrap = s->wrap; 426 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) 427 return Z_STREAM_ERROR; 428 429 /* when using zlib wrappers, compute Adler-32 for provided dictionary */ 430 if (wrap == 1) 431 strm->adler = adler32(strm->adler, dictionary, dictLength); 432 s->wrap = 0; /* avoid computing Adler-32 in read_buf */ 433 434 /* if dictionary would fill window, just replace the history */ 435 if (dictLength >= s->w_size) { 436 if (wrap == 0) { /* already empty otherwise */ 437 CLEAR_HASH(s); 438 s->strstart = 0; 439 s->block_start = 0L; 440 s->insert = 0; 441 } 442 dictionary += dictLength - s->w_size; /* use the tail */ 443 dictLength = s->w_size; 444 } 445 446 /* insert dictionary into window and hash */ 447 avail = strm->avail_in; 448 next = strm->next_in; 449 strm->avail_in = dictLength; 450 strm->next_in = (z_const Bytef *)dictionary; 451 fill_window(s); 452 while (s->lookahead >= MIN_MATCH) { 453 str = s->strstart; 454 n = s->lookahead - (MIN_MATCH-1); 455 do { 456 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 457 #ifndef FASTEST 458 s->prev[str & s->w_mask] = s->head[s->ins_h]; 459 #endif 460 s->head[s->ins_h] = (Pos)str; 461 str++; 462 } while (--n); 463 s->strstart = str; 464 s->lookahead = MIN_MATCH-1; 465 fill_window(s); 466 } 467 s->strstart += s->lookahead; 468 s->block_start = (long)s->strstart; 469 s->insert = s->lookahead; 470 s->lookahead = 0; 471 s->match_length = s->prev_length = MIN_MATCH-1; 472 s->match_available = 0; 473 strm->next_in = next; 474 strm->avail_in = avail; 475 s->wrap = wrap; 476 return Z_OK; 477 } 478 479 /* ========================================================================= */ 480 int ZEXPORT deflateGetDictionary ( 481 z_streamp strm, 482 Bytef *dictionary, 483 uInt *dictLength) 484 { 485 deflate_state *s; 486 uInt len; 487 488 if (deflateStateCheck(strm)) 489 return Z_STREAM_ERROR; 490 s = strm->state; 491 len = s->strstart + s->lookahead; 492 if (len > s->w_size) 493 len = s->w_size; 494 if (dictionary != Z_NULL && len) 495 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len); 496 if (dictLength != Z_NULL) 497 *dictLength = len; 498 return Z_OK; 499 } 500 501 /* ========================================================================= */ 502 int ZEXPORT deflateResetKeep ( 503 z_streamp strm) 504 { 505 deflate_state *s; 506 507 if (deflateStateCheck(strm)) { 508 return Z_STREAM_ERROR; 509 } 510 511 strm->total_in = strm->total_out = 0; 512 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 513 strm->data_type = Z_UNKNOWN; 514 515 s = (deflate_state *)strm->state; 516 s->pending = 0; 517 s->pending_out = s->pending_buf; 518 519 if (s->wrap < 0) { 520 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 521 } 522 s->status = 523 #ifdef GZIP 524 s->wrap == 2 ? GZIP_STATE : 525 #endif 526 INIT_STATE; 527 strm->adler = 528 #ifdef GZIP 529 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 530 #endif 531 adler32(0L, Z_NULL, 0); 532 s->last_flush = -2; 533 534 _tr_init(s); 535 536 return Z_OK; 537 } 538 539 /* ========================================================================= */ 540 int ZEXPORT deflateReset ( 541 z_streamp strm) 542 { 543 int ret; 544 545 ret = deflateResetKeep(strm); 546 if (ret == Z_OK) 547 lm_init(strm->state); 548 return ret; 549 } 550 551 /* ========================================================================= */ 552 int ZEXPORT deflateSetHeader ( 553 z_streamp strm, 554 gz_headerp head) 555 { 556 if (deflateStateCheck(strm) || strm->state->wrap != 2) 557 return Z_STREAM_ERROR; 558 strm->state->gzhead = head; 559 return Z_OK; 560 } 561 562 /* ========================================================================= */ 563 int ZEXPORT deflatePending ( 564 z_streamp strm, 565 unsigned *pending, 566 int *bits) 567 { 568 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 569 if (pending != Z_NULL) 570 *pending = strm->state->pending; 571 if (bits != Z_NULL) 572 *bits = strm->state->bi_valid; 573 return Z_OK; 574 } 575 576 /* ========================================================================= */ 577 int ZEXPORT deflatePrime ( 578 z_streamp strm, 579 int bits, 580 int value) 581 { 582 deflate_state *s; 583 int put; 584 585 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 586 s = strm->state; 587 if (bits < 0 || bits > 16 || 588 s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3)) 589 return Z_BUF_ERROR; 590 do { 591 put = Buf_size - s->bi_valid; 592 if (put > bits) 593 put = bits; 594 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); 595 s->bi_valid += put; 596 _tr_flush_bits(s); 597 value >>= put; 598 bits -= put; 599 } while (bits); 600 return Z_OK; 601 } 602 603 /* ========================================================================= */ 604 int ZEXPORT deflateParams( 605 z_streamp strm, 606 int level, 607 int strategy) 608 { 609 deflate_state *s; 610 compress_func func; 611 612 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 613 s = strm->state; 614 615 #ifdef FASTEST 616 if (level != 0) level = 1; 617 #else 618 if (level == Z_DEFAULT_COMPRESSION) level = 6; 619 #endif 620 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 621 return Z_STREAM_ERROR; 622 } 623 func = configuration_table[s->level].func; 624 625 if ((strategy != s->strategy || func != configuration_table[level].func) && 626 s->last_flush != -2) { 627 /* Flush the last buffer: */ 628 int err = deflate(strm, Z_BLOCK); 629 if (err == Z_STREAM_ERROR) 630 return err; 631 if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead) 632 return Z_BUF_ERROR; 633 } 634 if (s->level != level) { 635 if (s->level == 0 && s->matches != 0) { 636 if (s->matches == 1) 637 slide_hash(s); 638 else 639 CLEAR_HASH(s); 640 s->matches = 0; 641 } 642 s->level = level; 643 s->max_lazy_match = configuration_table[level].max_lazy; 644 s->good_match = configuration_table[level].good_length; 645 s->nice_match = configuration_table[level].nice_length; 646 s->max_chain_length = configuration_table[level].max_chain; 647 } 648 s->strategy = strategy; 649 return Z_OK; 650 } 651 652 /* ========================================================================= */ 653 int ZEXPORT deflateTune( 654 z_streamp strm, 655 int good_length, 656 int max_lazy, 657 int nice_length, 658 int max_chain) 659 { 660 deflate_state *s; 661 662 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 663 s = strm->state; 664 s->good_match = (uInt)good_length; 665 s->max_lazy_match = (uInt)max_lazy; 666 s->nice_match = nice_length; 667 s->max_chain_length = (uInt)max_chain; 668 return Z_OK; 669 } 670 671 /* ========================================================================= 672 * For the default windowBits of 15 and memLevel of 8, this function returns a 673 * close to exact, as well as small, upper bound on the compressed size. This 674 * is an expansion of ~0.03%, plus a small constant. 675 * 676 * For any setting other than those defaults for windowBits and memLevel, one 677 * of two worst case bounds is returned. This is at most an expansion of ~4% or 678 * ~13%, plus a small constant. 679 * 680 * Both the 0.03% and 4% derive from the overhead of stored blocks. The first 681 * one is for stored blocks of 16383 bytes (memLevel == 8), whereas the second 682 * is for stored blocks of 127 bytes (the worst case memLevel == 1). The 683 * expansion results from five bytes of header for each stored block. 684 * 685 * The larger expansion of 13% results from a window size less than or equal to 686 * the symbols buffer size (windowBits <= memLevel + 7). In that case some of 687 * the data being compressed may have slid out of the sliding window, impeding 688 * a stored block from being emitted. Then the only choice is a fixed or 689 * dynamic block, where a fixed block limits the maximum expansion to 9 bits 690 * per 8-bit byte, plus 10 bits for every block. The smallest block size for 691 * which this can occur is 255 (memLevel == 2). 692 * 693 * Shifts are used to approximate divisions, for speed. 694 */ 695 uLong ZEXPORT deflateBound( 696 z_streamp strm, 697 uLong sourceLen) 698 { 699 deflate_state *s; 700 uLong fixedlen, storelen, wraplen; 701 702 /* upper bound for fixed blocks with 9-bit literals and length 255 703 (memLevel == 2, which is the lowest that may not use stored blocks) -- 704 ~13% overhead plus a small constant */ 705 fixedlen = sourceLen + (sourceLen >> 3) + (sourceLen >> 8) + 706 (sourceLen >> 9) + 4; 707 708 /* upper bound for stored blocks with length 127 (memLevel == 1) -- 709 ~4% overhead plus a small constant */ 710 storelen = sourceLen + (sourceLen >> 5) + (sourceLen >> 7) + 711 (sourceLen >> 11) + 7; 712 713 /* if can't get parameters, return larger bound plus a zlib wrapper */ 714 if (deflateStateCheck(strm)) 715 return (fixedlen > storelen ? fixedlen : storelen) + 6; 716 717 /* compute wrapper length */ 718 s = strm->state; 719 switch (s->wrap) { 720 case 0: /* raw deflate */ 721 wraplen = 0; 722 break; 723 case 1: /* zlib wrapper */ 724 wraplen = 6 + (s->strstart ? 4 : 0); 725 break; 726 #ifdef GZIP 727 case 2: /* gzip wrapper */ 728 wraplen = 18; 729 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 730 Bytef *str; 731 if (s->gzhead->extra != Z_NULL) 732 wraplen += 2 + s->gzhead->extra_len; 733 str = s->gzhead->name; 734 if (str != Z_NULL) 735 do { 736 wraplen++; 737 } while (*str++); 738 str = s->gzhead->comment; 739 if (str != Z_NULL) 740 do { 741 wraplen++; 742 } while (*str++); 743 if (s->gzhead->hcrc) 744 wraplen += 2; 745 } 746 break; 747 #endif 748 default: /* for compiler happiness */ 749 wraplen = 6; 750 } 751 752 /* if not default parameters, return one of the conservative bounds */ 753 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 754 return (s->w_bits <= s->hash_bits ? fixedlen : storelen) + wraplen; 755 756 /* default settings: return tight bound for that case -- ~0.03% overhead 757 plus a small constant */ 758 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 759 (sourceLen >> 25) + 13 - 6 + wraplen; 760 } 761 762 /* ========================================================================= 763 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 764 * IN assertion: the stream state is correct and there is enough room in 765 * pending_buf. 766 */ 767 local void putShortMSB ( 768 deflate_state *s, 769 uInt b) 770 { 771 put_byte(s, (Byte)(b >> 8)); 772 put_byte(s, (Byte)(b & 0xff)); 773 } 774 775 /* ========================================================================= 776 * Flush as much pending output as possible. All deflate() output, except for 777 * some deflate_stored() output, goes through this function so some 778 * applications may wish to modify it to avoid allocating a large 779 * strm->next_out buffer and copying into it. (See also read_buf()). 780 */ 781 local void flush_pending( 782 z_streamp strm) 783 { 784 unsigned len; 785 deflate_state *s = strm->state; 786 787 _tr_flush_bits(s); 788 len = s->pending; 789 if (len > strm->avail_out) len = strm->avail_out; 790 if (len == 0) return; 791 792 zmemcpy(strm->next_out, s->pending_out, len); 793 strm->next_out += len; 794 s->pending_out += len; 795 strm->total_out += len; 796 strm->avail_out -= len; 797 s->pending -= len; 798 if (s->pending == 0) { 799 s->pending_out = s->pending_buf; 800 } 801 } 802 803 /* =========================================================================== 804 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1]. 805 */ 806 #define HCRC_UPDATE(beg) \ 807 do { \ 808 if (s->gzhead->hcrc && s->pending > (beg)) \ 809 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \ 810 s->pending - (beg)); \ 811 } while (0) 812 813 /* ========================================================================= */ 814 int ZEXPORT deflate ( 815 z_streamp strm, 816 int flush) 817 { 818 int old_flush; /* value of flush param for previous deflate call */ 819 deflate_state *s; 820 821 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { 822 return Z_STREAM_ERROR; 823 } 824 s = strm->state; 825 826 if (strm->next_out == Z_NULL || 827 (strm->avail_in != 0 && strm->next_in == Z_NULL) || 828 (s->status == FINISH_STATE && flush != Z_FINISH)) { 829 ERR_RETURN(strm, Z_STREAM_ERROR); 830 } 831 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 832 833 old_flush = s->last_flush; 834 s->last_flush = flush; 835 836 /* Flush as much pending output as possible */ 837 if (s->pending != 0) { 838 flush_pending(strm); 839 if (strm->avail_out == 0) { 840 /* Since avail_out is 0, deflate will be called again with 841 * more output space, but possibly with both pending and 842 * avail_in equal to zero. There won't be anything to do, 843 * but this is not an error situation so make sure we 844 * return OK instead of BUF_ERROR at next call of deflate: 845 */ 846 s->last_flush = -1; 847 return Z_OK; 848 } 849 850 /* Make sure there is something to do and avoid duplicate consecutive 851 * flushes. For repeated and useless calls with Z_FINISH, we keep 852 * returning Z_STREAM_END instead of Z_BUF_ERROR. 853 */ 854 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 855 flush != Z_FINISH) { 856 ERR_RETURN(strm, Z_BUF_ERROR); 857 } 858 859 /* User must not provide more input after the first FINISH: */ 860 if (s->status == FINISH_STATE && strm->avail_in != 0) { 861 ERR_RETURN(strm, Z_BUF_ERROR); 862 } 863 864 /* Write the header */ 865 if (s->status == INIT_STATE && s->wrap == 0) 866 s->status = BUSY_STATE; 867 if (s->status == INIT_STATE) { 868 /* zlib header */ 869 uInt header = (Z_DEFLATED + ((s->w_bits - 8) << 4)) << 8; 870 uInt level_flags; 871 872 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 873 level_flags = 0; 874 else if (s->level < 6) 875 level_flags = 1; 876 else if (s->level == 6) 877 level_flags = 2; 878 else 879 level_flags = 3; 880 header |= (level_flags << 6); 881 if (s->strstart != 0) header |= PRESET_DICT; 882 header += 31 - (header % 31); 883 884 putShortMSB(s, header); 885 886 /* Save the adler32 of the preset dictionary: */ 887 if (s->strstart != 0) { 888 putShortMSB(s, (uInt)(strm->adler >> 16)); 889 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 890 } 891 strm->adler = adler32(0L, Z_NULL, 0); 892 s->status = BUSY_STATE; 893 894 /* Compression must start with an empty pending buffer */ 895 flush_pending(strm); 896 if (s->pending != 0) { 897 s->last_flush = -1; 898 return Z_OK; 899 } 900 } 901 #ifdef GZIP 902 if (s->status == GZIP_STATE) { 903 /* gzip header */ 904 strm->adler = crc32(0L, Z_NULL, 0); 905 put_byte(s, 31); 906 put_byte(s, 139); 907 put_byte(s, 8); 908 if (s->gzhead == Z_NULL) { 909 put_byte(s, 0); 910 put_byte(s, 0); 911 put_byte(s, 0); 912 put_byte(s, 0); 913 put_byte(s, 0); 914 put_byte(s, s->level == 9 ? 2 : 915 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 916 4 : 0)); 917 put_byte(s, OS_CODE); 918 s->status = BUSY_STATE; 919 920 /* Compression must start with an empty pending buffer */ 921 flush_pending(strm); 922 if (s->pending != 0) { 923 s->last_flush = -1; 924 return Z_OK; 925 } 926 } 927 else { 928 put_byte(s, (s->gzhead->text ? 1 : 0) + 929 (s->gzhead->hcrc ? 2 : 0) + 930 (s->gzhead->extra == Z_NULL ? 0 : 4) + 931 (s->gzhead->name == Z_NULL ? 0 : 8) + 932 (s->gzhead->comment == Z_NULL ? 0 : 16) 933 ); 934 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 935 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 936 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 937 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 938 put_byte(s, s->level == 9 ? 2 : 939 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 940 4 : 0)); 941 put_byte(s, s->gzhead->os & 0xff); 942 if (s->gzhead->extra != Z_NULL) { 943 put_byte(s, s->gzhead->extra_len & 0xff); 944 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 945 } 946 if (s->gzhead->hcrc) 947 strm->adler = crc32(strm->adler, s->pending_buf, 948 s->pending); 949 s->gzindex = 0; 950 s->status = EXTRA_STATE; 951 } 952 } 953 if (s->status == EXTRA_STATE) { 954 if (s->gzhead->extra != Z_NULL) { 955 ulg beg = s->pending; /* start of bytes to update crc */ 956 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex; 957 while (s->pending + left > s->pending_buf_size) { 958 uInt copy = s->pending_buf_size - s->pending; 959 zmemcpy(s->pending_buf + s->pending, 960 s->gzhead->extra + s->gzindex, copy); 961 s->pending = s->pending_buf_size; 962 HCRC_UPDATE(beg); 963 s->gzindex += copy; 964 flush_pending(strm); 965 if (s->pending != 0) { 966 s->last_flush = -1; 967 return Z_OK; 968 } 969 beg = 0; 970 left -= copy; 971 } 972 zmemcpy(s->pending_buf + s->pending, 973 s->gzhead->extra + s->gzindex, left); 974 s->pending += left; 975 HCRC_UPDATE(beg); 976 s->gzindex = 0; 977 } 978 s->status = NAME_STATE; 979 } 980 if (s->status == NAME_STATE) { 981 if (s->gzhead->name != Z_NULL) { 982 ulg beg = s->pending; /* start of bytes to update crc */ 983 int val; 984 do { 985 if (s->pending == s->pending_buf_size) { 986 HCRC_UPDATE(beg); 987 flush_pending(strm); 988 if (s->pending != 0) { 989 s->last_flush = -1; 990 return Z_OK; 991 } 992 beg = 0; 993 } 994 val = s->gzhead->name[s->gzindex++]; 995 put_byte(s, val); 996 } while (val != 0); 997 HCRC_UPDATE(beg); 998 s->gzindex = 0; 999 } 1000 s->status = COMMENT_STATE; 1001 } 1002 if (s->status == COMMENT_STATE) { 1003 if (s->gzhead->comment != Z_NULL) { 1004 ulg beg = s->pending; /* start of bytes to update crc */ 1005 int val; 1006 do { 1007 if (s->pending == s->pending_buf_size) { 1008 HCRC_UPDATE(beg); 1009 flush_pending(strm); 1010 if (s->pending != 0) { 1011 s->last_flush = -1; 1012 return Z_OK; 1013 } 1014 beg = 0; 1015 } 1016 val = s->gzhead->comment[s->gzindex++]; 1017 put_byte(s, val); 1018 } while (val != 0); 1019 HCRC_UPDATE(beg); 1020 } 1021 s->status = HCRC_STATE; 1022 } 1023 if (s->status == HCRC_STATE) { 1024 if (s->gzhead->hcrc) { 1025 if (s->pending + 2 > s->pending_buf_size) { 1026 flush_pending(strm); 1027 if (s->pending != 0) { 1028 s->last_flush = -1; 1029 return Z_OK; 1030 } 1031 } 1032 put_byte(s, (Byte)(strm->adler & 0xff)); 1033 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1034 strm->adler = crc32(0L, Z_NULL, 0); 1035 } 1036 s->status = BUSY_STATE; 1037 1038 /* Compression must start with an empty pending buffer */ 1039 flush_pending(strm); 1040 if (s->pending != 0) { 1041 s->last_flush = -1; 1042 return Z_OK; 1043 } 1044 } 1045 #endif 1046 1047 /* Start a new block or continue the current one. 1048 */ 1049 if (strm->avail_in != 0 || s->lookahead != 0 || 1050 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 1051 block_state bstate; 1052 1053 bstate = s->level == 0 ? deflate_stored(s, flush) : 1054 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 1055 s->strategy == Z_RLE ? deflate_rle(s, flush) : 1056 (*(configuration_table[s->level].func))(s, flush); 1057 1058 if (bstate == finish_started || bstate == finish_done) { 1059 s->status = FINISH_STATE; 1060 } 1061 if (bstate == need_more || bstate == finish_started) { 1062 if (strm->avail_out == 0) { 1063 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 1064 } 1065 return Z_OK; 1066 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 1067 * of deflate should use the same flush parameter to make sure 1068 * that the flush is complete. So we don't have to output an 1069 * empty block here, this will be done at next call. This also 1070 * ensures that for a very small output buffer, we emit at most 1071 * one empty block. 1072 */ 1073 } 1074 if (bstate == block_done) { 1075 if (flush == Z_PARTIAL_FLUSH) { 1076 _tr_align(s); 1077 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 1078 _tr_stored_block(s, (char*)0, 0L, 0); 1079 /* For a full flush, this empty block will be recognized 1080 * as a special marker by inflate_sync(). 1081 */ 1082 if (flush == Z_FULL_FLUSH) { 1083 CLEAR_HASH(s); /* forget history */ 1084 if (s->lookahead == 0) { 1085 s->strstart = 0; 1086 s->block_start = 0L; 1087 s->insert = 0; 1088 } 1089 } 1090 } 1091 flush_pending(strm); 1092 if (strm->avail_out == 0) { 1093 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 1094 return Z_OK; 1095 } 1096 } 1097 } 1098 1099 if (flush != Z_FINISH) return Z_OK; 1100 if (s->wrap <= 0) return Z_STREAM_END; 1101 1102 /* Write the trailer */ 1103 #ifdef GZIP 1104 if (s->wrap == 2) { 1105 put_byte(s, (Byte)(strm->adler & 0xff)); 1106 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1107 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 1108 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 1109 put_byte(s, (Byte)(strm->total_in & 0xff)); 1110 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 1111 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 1112 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 1113 } 1114 else 1115 #endif 1116 { 1117 putShortMSB(s, (uInt)(strm->adler >> 16)); 1118 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1119 } 1120 flush_pending(strm); 1121 /* If avail_out is zero, the application will call deflate again 1122 * to flush the rest. 1123 */ 1124 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 1125 return s->pending != 0 ? Z_OK : Z_STREAM_END; 1126 } 1127 1128 /* ========================================================================= */ 1129 int ZEXPORT deflateEnd ( 1130 z_streamp strm) 1131 { 1132 int status; 1133 1134 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 1135 1136 status = strm->state->status; 1137 1138 /* Deallocate in reverse order of allocations: */ 1139 TRY_FREE(strm, strm->state->pending_buf); 1140 TRY_FREE(strm, strm->state->head); 1141 TRY_FREE(strm, strm->state->prev); 1142 TRY_FREE(strm, strm->state->window); 1143 1144 ZFREE(strm, strm->state); 1145 strm->state = Z_NULL; 1146 1147 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1148 } 1149 1150 /* ========================================================================= 1151 * Copy the source state to the destination state. 1152 * To simplify the source, this is not supported for 16-bit MSDOS (which 1153 * doesn't have enough memory anyway to duplicate compression states). 1154 */ 1155 int ZEXPORT deflateCopy ( 1156 z_streamp dest, 1157 z_streamp source) 1158 { 1159 #ifdef MAXSEG_64K 1160 return Z_STREAM_ERROR; 1161 #else 1162 deflate_state *ds; 1163 deflate_state *ss; 1164 1165 1166 if (deflateStateCheck(source) || dest == Z_NULL) { 1167 return Z_STREAM_ERROR; 1168 } 1169 1170 ss = source->state; 1171 1172 zmemcpy((Bytef*)dest, (Bytef*)source, sizeof(z_stream)); 1173 1174 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1175 if (ds == Z_NULL) return Z_MEM_ERROR; 1176 dest->state = (struct internal_state FAR *) ds; 1177 zmemcpy((Bytef*)ds, (Bytef*)ss, sizeof(deflate_state)); 1178 ds->strm = dest; 1179 1180 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1181 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1182 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1183 ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, 4); 1184 1185 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1186 ds->pending_buf == Z_NULL) { 1187 deflateEnd (dest); 1188 return Z_MEM_ERROR; 1189 } 1190 /* following zmemcpy do not work for 16-bit MSDOS */ 1191 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1192 zmemcpy((Bytef*)ds->prev, (Bytef*)ss->prev, ds->w_size * sizeof(Pos)); 1193 zmemcpy((Bytef*)ds->head, (Bytef*)ss->head, ds->hash_size * sizeof(Pos)); 1194 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); 1195 1196 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1197 ds->sym_buf = ds->pending_buf + ds->lit_bufsize; 1198 1199 ds->l_desc.dyn_tree = ds->dyn_ltree; 1200 ds->d_desc.dyn_tree = ds->dyn_dtree; 1201 ds->bl_desc.dyn_tree = ds->bl_tree; 1202 1203 return Z_OK; 1204 #endif /* MAXSEG_64K */ 1205 } 1206 1207 /* =========================================================================== 1208 * Read a new buffer from the current input stream, update the adler32 1209 * and total number of bytes read. All deflate() input goes through 1210 * this function so some applications may wish to modify it to avoid 1211 * allocating a large strm->next_in buffer and copying from it. 1212 * (See also flush_pending()). 1213 */ 1214 local unsigned read_buf( 1215 z_streamp strm, 1216 Bytef *buf, 1217 unsigned size) 1218 { 1219 unsigned len = strm->avail_in; 1220 1221 if (len > size) len = size; 1222 if (len == 0) return 0; 1223 1224 strm->avail_in -= len; 1225 1226 zmemcpy(buf, strm->next_in, len); 1227 if (strm->state->wrap == 1) { 1228 strm->adler = adler32(strm->adler, buf, len); 1229 } 1230 #ifdef GZIP 1231 else if (strm->state->wrap == 2) { 1232 strm->adler = crc32(strm->adler, buf, len); 1233 } 1234 #endif 1235 strm->next_in += len; 1236 strm->total_in += len; 1237 1238 return len; 1239 } 1240 1241 /* =========================================================================== 1242 * Initialize the "longest match" routines for a new zlib stream 1243 */ 1244 local void lm_init ( 1245 deflate_state *s) 1246 { 1247 s->window_size = (ulg)2L*s->w_size; 1248 1249 CLEAR_HASH(s); 1250 1251 /* Set the default configuration parameters: 1252 */ 1253 s->max_lazy_match = configuration_table[s->level].max_lazy; 1254 s->good_match = configuration_table[s->level].good_length; 1255 s->nice_match = configuration_table[s->level].nice_length; 1256 s->max_chain_length = configuration_table[s->level].max_chain; 1257 1258 s->strstart = 0; 1259 s->block_start = 0L; 1260 s->lookahead = 0; 1261 s->insert = 0; 1262 s->match_length = s->prev_length = MIN_MATCH-1; 1263 s->match_available = 0; 1264 s->ins_h = 0; 1265 } 1266 1267 #ifndef FASTEST 1268 /* =========================================================================== 1269 * Set match_start to the longest match starting at the given string and 1270 * return its length. Matches shorter or equal to prev_length are discarded, 1271 * in which case the result is equal to prev_length and match_start is 1272 * garbage. 1273 * IN assertions: cur_match is the head of the hash chain for the current 1274 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1275 * OUT assertion: the match length is not greater than s->lookahead. 1276 */ 1277 local uInt longest_match( 1278 deflate_state *s, 1279 IPos cur_match) 1280 { 1281 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1282 Bytef *scan = s->window + s->strstart; /* current string */ 1283 Bytef *match; /* matched string */ 1284 int len; /* length of current match */ 1285 int best_len = (int)s->prev_length; /* best match length so far */ 1286 int nice_match = s->nice_match; /* stop if match long enough */ 1287 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1288 s->strstart - (IPos)MAX_DIST(s) : NIL; 1289 /* Stop when cur_match becomes <= limit. To simplify the code, 1290 * we prevent matches with the string of window index 0. 1291 */ 1292 Posf *prev = s->prev; 1293 uInt wmask = s->w_mask; 1294 1295 #ifdef UNALIGNED_OK 1296 /* Compare two bytes at a time. Note: this is not always beneficial. 1297 * Try with and without -DUNALIGNED_OK to check. 1298 */ 1299 Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1300 ush scan_start = *(ushf*)scan; 1301 ush scan_end = *(ushf*)(scan + best_len - 1); 1302 #else 1303 Bytef *strend = s->window + s->strstart + MAX_MATCH; 1304 Byte scan_end1 = scan[best_len - 1]; 1305 Byte scan_end = scan[best_len]; 1306 #endif 1307 1308 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1309 * It is easy to get rid of this optimization if necessary. 1310 */ 1311 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1312 1313 /* Do not waste too much time if we already have a good match: */ 1314 if (s->prev_length >= s->good_match) { 1315 chain_length >>= 2; 1316 } 1317 /* Do not look for matches beyond the end of the input. This is necessary 1318 * to make deflate deterministic. 1319 */ 1320 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead; 1321 1322 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1323 "need lookahead"); 1324 1325 do { 1326 Assert(cur_match < s->strstart, "no future"); 1327 match = s->window + cur_match; 1328 1329 /* Skip to next match if the match length cannot increase 1330 * or if the match length is less than 2. Note that the checks below 1331 * for insufficient lookahead only occur occasionally for performance 1332 * reasons. Therefore uninitialized memory will be accessed, and 1333 * conditional jumps will be made that depend on those values. 1334 * However the length of the match is limited to the lookahead, so 1335 * the output of deflate is not affected by the uninitialized values. 1336 */ 1337 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1338 /* This code assumes sizeof(unsigned short) == 2. Do not use 1339 * UNALIGNED_OK if your compiler uses a different size. 1340 */ 1341 if (*(ushf*)(match + best_len - 1) != scan_end || 1342 *(ushf*)match != scan_start) continue; 1343 1344 /* It is not necessary to compare scan[2] and match[2] since they are 1345 * always equal when the other bytes match, given that the hash keys 1346 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1347 * strstart + 3, + 5, up to strstart + 257. We check for insufficient 1348 * lookahead only every 4th comparison; the 128th check will be made 1349 * at strstart + 257. If MAX_MATCH-2 is not a multiple of 8, it is 1350 * necessary to put more guard bytes at the end of the window, or 1351 * to check more often for insufficient lookahead. 1352 */ 1353 Assert(scan[2] == match[2], "scan[2]?"); 1354 scan++, match++; 1355 do { 1356 } while (*(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1357 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1358 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1359 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1360 scan < strend); 1361 /* The funny "do {}" generates better code on most compilers */ 1362 1363 /* Here, scan <= window + strstart + 257 */ 1364 Assert(scan <= s->window + (unsigned)(s->window_size - 1), 1365 "wild scan"); 1366 if (*scan == *match) scan++; 1367 1368 len = (MAX_MATCH - 1) - (int)(strend - scan); 1369 scan = strend - (MAX_MATCH-1); 1370 1371 #else /* UNALIGNED_OK */ 1372 1373 if (match[best_len] != scan_end || 1374 match[best_len - 1] != scan_end1 || 1375 *match != *scan || 1376 *++match != scan[1]) continue; 1377 1378 /* The check at best_len - 1 can be removed because it will be made 1379 * again later. (This heuristic is not always a win.) 1380 * It is not necessary to compare scan[2] and match[2] since they 1381 * are always equal when the other bytes match, given that 1382 * the hash keys are equal and that HASH_BITS >= 8. 1383 */ 1384 scan += 2, match++; 1385 Assert(*scan == *match, "match[2]?"); 1386 1387 /* We check for insufficient lookahead only every 8th comparison; 1388 * the 256th check will be made at strstart + 258. 1389 */ 1390 do { 1391 } while (*++scan == *++match && *++scan == *++match && 1392 *++scan == *++match && *++scan == *++match && 1393 *++scan == *++match && *++scan == *++match && 1394 *++scan == *++match && *++scan == *++match && 1395 scan < strend); 1396 1397 Assert(scan <= s->window + (unsigned)(s->window_size - 1), 1398 "wild scan"); 1399 1400 len = MAX_MATCH - (int)(strend - scan); 1401 scan = strend - MAX_MATCH; 1402 1403 #endif /* UNALIGNED_OK */ 1404 1405 if (len > best_len) { 1406 s->match_start = cur_match; 1407 best_len = len; 1408 if (len >= nice_match) break; 1409 #ifdef UNALIGNED_OK 1410 scan_end = *(ushf*)(scan + best_len - 1); 1411 #else 1412 scan_end1 = scan[best_len - 1]; 1413 scan_end = scan[best_len]; 1414 #endif 1415 } 1416 } while ((cur_match = prev[cur_match & wmask]) > limit 1417 && --chain_length != 0); 1418 1419 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1420 return s->lookahead; 1421 } 1422 1423 #else /* FASTEST */ 1424 1425 /* --------------------------------------------------------------------------- 1426 * Optimized version for FASTEST only 1427 */ 1428 local uInt longest_match( 1429 deflate_state *s, 1430 IPos cur_match) 1431 { 1432 Bytef *scan = s->window + s->strstart; /* current string */ 1433 Bytef *match; /* matched string */ 1434 int len; /* length of current match */ 1435 Bytef *strend = s->window + s->strstart + MAX_MATCH; 1436 1437 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1438 * It is easy to get rid of this optimization if necessary. 1439 */ 1440 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1441 1442 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1443 "need lookahead"); 1444 1445 Assert(cur_match < s->strstart, "no future"); 1446 1447 match = s->window + cur_match; 1448 1449 /* Return failure if the match length is less than 2: 1450 */ 1451 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1452 1453 /* The check at best_len - 1 can be removed because it will be made 1454 * again later. (This heuristic is not always a win.) 1455 * It is not necessary to compare scan[2] and match[2] since they 1456 * are always equal when the other bytes match, given that 1457 * the hash keys are equal and that HASH_BITS >= 8. 1458 */ 1459 scan += 2, match += 2; 1460 Assert(*scan == *match, "match[2]?"); 1461 1462 /* We check for insufficient lookahead only every 8th comparison; 1463 * the 256th check will be made at strstart + 258. 1464 */ 1465 do { 1466 } while (*++scan == *++match && *++scan == *++match && 1467 *++scan == *++match && *++scan == *++match && 1468 *++scan == *++match && *++scan == *++match && 1469 *++scan == *++match && *++scan == *++match && 1470 scan < strend); 1471 1472 Assert(scan <= s->window + (unsigned)(s->window_size - 1), "wild scan"); 1473 1474 len = MAX_MATCH - (int)(strend - scan); 1475 1476 if (len < MIN_MATCH) return MIN_MATCH - 1; 1477 1478 s->match_start = cur_match; 1479 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1480 } 1481 1482 #endif /* FASTEST */ 1483 1484 #ifdef ZLIB_DEBUG 1485 1486 #define EQUAL 0 1487 /* result of memcmp for equal strings */ 1488 1489 /* =========================================================================== 1490 * Check that the match at match_start is indeed a match. 1491 */ 1492 local void check_match( 1493 deflate_state *s, 1494 IPos start, 1495 IPos match, 1496 int length) 1497 { 1498 /* check that the match is indeed a match */ 1499 if (zmemcmp(s->window + match, 1500 s->window + start, length) != EQUAL) { 1501 fprintf(stderr, " start %u, match %u, length %d\n", 1502 start, match, length); 1503 do { 1504 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); 1505 } while (--length != 0); 1506 z_error("invalid match"); 1507 } 1508 if (z_verbose > 1) { 1509 fprintf(stderr,"\\[%d,%d]", start - match, length); 1510 do { putc(s->window[start++], stderr); } while (--length != 0); 1511 } 1512 } 1513 #else 1514 # define check_match(s, start, match, length) 1515 #endif /* ZLIB_DEBUG */ 1516 1517 /* =========================================================================== 1518 * Fill the window when the lookahead becomes insufficient. 1519 * Updates strstart and lookahead. 1520 * 1521 * IN assertion: lookahead < MIN_LOOKAHEAD 1522 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 1523 * At least one byte has been read, or avail_in == 0; reads are 1524 * performed for at least two bytes (required for the zip translate_eol 1525 * option -- not supported here). 1526 */ 1527 local void fill_window( 1528 deflate_state *s) 1529 { 1530 unsigned n; 1531 unsigned more; /* Amount of free space at the end of the window. */ 1532 uInt wsize = s->w_size; 1533 1534 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); 1535 1536 do { 1537 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 1538 1539 /* Deal with !@#$% 64K limit: */ 1540 if (sizeof(int) <= 2) { 1541 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 1542 more = wsize; 1543 1544 } else if (more == (unsigned)(-1)) { 1545 /* Very unlikely, but possible on 16 bit machine if 1546 * strstart == 0 && lookahead == 1 (input done a byte at time) 1547 */ 1548 more--; 1549 } 1550 } 1551 1552 /* If the window is almost full and there is insufficient lookahead, 1553 * move the upper half to the lower one to make room in the upper half. 1554 */ 1555 if (s->strstart >= wsize + MAX_DIST(s)) { 1556 1557 zmemcpy(s->window, s->window + wsize, (unsigned)wsize - more); 1558 s->match_start -= wsize; 1559 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 1560 s->block_start -= (long) wsize; 1561 if (s->insert > s->strstart) 1562 s->insert = s->strstart; 1563 slide_hash(s); 1564 more += wsize; 1565 } 1566 if (s->strm->avail_in == 0) break; 1567 1568 /* If there was no sliding: 1569 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 1570 * more == window_size - lookahead - strstart 1571 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 1572 * => more >= window_size - 2*WSIZE + 2 1573 * In the BIG_MEM or MMAP case (not yet supported), 1574 * window_size == input_size + MIN_LOOKAHEAD && 1575 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 1576 * Otherwise, window_size == 2*WSIZE so more >= 2. 1577 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 1578 */ 1579 Assert(more >= 2, "more < 2"); 1580 1581 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 1582 s->lookahead += n; 1583 1584 /* Initialize the hash value now that we have some input: */ 1585 if (s->lookahead + s->insert >= MIN_MATCH) { 1586 uInt str = s->strstart - s->insert; 1587 s->ins_h = s->window[str]; 1588 UPDATE_HASH(s, s->ins_h, s->window[str + 1]); 1589 #if MIN_MATCH != 3 1590 Call UPDATE_HASH() MIN_MATCH-3 more times 1591 #endif 1592 while (s->insert) { 1593 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 1594 #ifndef FASTEST 1595 s->prev[str & s->w_mask] = s->head[s->ins_h]; 1596 #endif 1597 s->head[s->ins_h] = (Pos)str; 1598 str++; 1599 s->insert--; 1600 if (s->lookahead + s->insert < MIN_MATCH) 1601 break; 1602 } 1603 } 1604 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 1605 * but this is not important since only literal bytes will be emitted. 1606 */ 1607 1608 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 1609 1610 /* If the WIN_INIT bytes after the end of the current data have never been 1611 * written, then zero those bytes in order to avoid memory check reports of 1612 * the use of uninitialized (or uninitialised as Julian writes) bytes by 1613 * the longest match routines. Update the high water mark for the next 1614 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 1615 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 1616 */ 1617 if (s->high_water < s->window_size) { 1618 ulg curr = s->strstart + (ulg)(s->lookahead); 1619 ulg init; 1620 1621 if (s->high_water < curr) { 1622 /* Previous high water mark below current data -- zero WIN_INIT 1623 * bytes or up to end of window, whichever is less. 1624 */ 1625 init = s->window_size - curr; 1626 if (init > WIN_INIT) 1627 init = WIN_INIT; 1628 zmemzero(s->window + curr, (unsigned)init); 1629 s->high_water = curr + init; 1630 } 1631 else if (s->high_water < (ulg)curr + WIN_INIT) { 1632 /* High water mark at or above current data, but below current data 1633 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 1634 * to end of window, whichever is less. 1635 */ 1636 init = (ulg)curr + WIN_INIT - s->high_water; 1637 if (init > s->window_size - s->high_water) 1638 init = s->window_size - s->high_water; 1639 zmemzero(s->window + s->high_water, (unsigned)init); 1640 s->high_water += init; 1641 } 1642 } 1643 1644 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1645 "not enough room for search"); 1646 } 1647 1648 /* =========================================================================== 1649 * Flush the current block, with given end-of-file flag. 1650 * IN assertion: strstart is set to the end of the current match. 1651 */ 1652 #define FLUSH_BLOCK_ONLY(s, last) { \ 1653 _tr_flush_block(s, (s->block_start >= 0L ? \ 1654 (charf *)&s->window[(unsigned)s->block_start] : \ 1655 (charf *)Z_NULL), \ 1656 (ulg)((long)s->strstart - s->block_start), \ 1657 (last)); \ 1658 s->block_start = s->strstart; \ 1659 flush_pending(s->strm); \ 1660 Tracev((stderr,"[FLUSH]")); \ 1661 } 1662 1663 /* Same but force premature exit if necessary. */ 1664 #define FLUSH_BLOCK(s, last) { \ 1665 FLUSH_BLOCK_ONLY(s, last); \ 1666 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1667 } 1668 1669 /* Maximum stored block length in deflate format (not including header). */ 1670 #define MAX_STORED 65535 1671 1672 /* Minimum of a and b. */ 1673 #define MIN(a, b) ((a) > (b) ? (b) : (a)) 1674 1675 /* =========================================================================== 1676 * Copy without compression as much as possible from the input stream, return 1677 * the current block state. 1678 * 1679 * In case deflateParams() is used to later switch to a non-zero compression 1680 * level, s->matches (otherwise unused when storing) keeps track of the number 1681 * of hash table slides to perform. If s->matches is 1, then one hash table 1682 * slide will be done when switching. If s->matches is 2, the maximum value 1683 * allowed here, then the hash table will be cleared, since two or more slides 1684 * is the same as a clear. 1685 * 1686 * deflate_stored() is written to minimize the number of times an input byte is 1687 * copied. It is most efficient with large input and output buffers, which 1688 * maximizes the opportunities to have a single copy from next_in to next_out. 1689 */ 1690 local block_state deflate_stored( 1691 deflate_state *s, 1692 int flush) 1693 { 1694 /* Smallest worthy block size when not flushing or finishing. By default 1695 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For 1696 * large input and output buffers, the stored block size will be larger. 1697 */ 1698 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size); 1699 1700 /* Copy as many min_block or larger stored blocks directly to next_out as 1701 * possible. If flushing, copy the remaining available input to next_out as 1702 * stored blocks, if there is enough space. 1703 */ 1704 unsigned len, left, have, last = 0; 1705 unsigned used = s->strm->avail_in; 1706 do { 1707 /* Set len to the maximum size block that we can copy directly with the 1708 * available input data and output space. Set left to how much of that 1709 * would be copied from what's left in the window. 1710 */ 1711 len = MAX_STORED; /* maximum deflate stored block length */ 1712 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1713 if (s->strm->avail_out < have) /* need room for header */ 1714 break; 1715 /* maximum stored block length that will fit in avail_out: */ 1716 have = s->strm->avail_out - have; 1717 left = s->strstart - s->block_start; /* bytes left in window */ 1718 if (len > (ulg)left + s->strm->avail_in) 1719 len = left + s->strm->avail_in; /* limit len to the input */ 1720 if (len > have) 1721 len = have; /* limit len to the output */ 1722 1723 /* If the stored block would be less than min_block in length, or if 1724 * unable to copy all of the available input when flushing, then try 1725 * copying to the window and the pending buffer instead. Also don't 1726 * write an empty block when flushing -- deflate() does that. 1727 */ 1728 if (len < min_block && ((len == 0 && flush != Z_FINISH) || 1729 flush == Z_NO_FLUSH || 1730 len != left + s->strm->avail_in)) 1731 break; 1732 1733 /* Make a dummy stored block in pending to get the header bytes, 1734 * including any pending bits. This also updates the debugging counts. 1735 */ 1736 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0; 1737 _tr_stored_block(s, (char *)0, 0L, last); 1738 1739 /* Replace the lengths in the dummy stored block with len. */ 1740 s->pending_buf[s->pending - 4] = len; 1741 s->pending_buf[s->pending - 3] = len >> 8; 1742 s->pending_buf[s->pending - 2] = ~len; 1743 s->pending_buf[s->pending - 1] = ~len >> 8; 1744 1745 /* Write the stored block header bytes. */ 1746 flush_pending(s->strm); 1747 1748 #ifdef ZLIB_DEBUG 1749 /* Update debugging counts for the data about to be copied. */ 1750 s->compressed_len += len << 3; 1751 s->bits_sent += len << 3; 1752 #endif 1753 1754 /* Copy uncompressed bytes from the window to next_out. */ 1755 if (left) { 1756 if (left > len) 1757 left = len; 1758 zmemcpy(s->strm->next_out, s->window + s->block_start, left); 1759 s->strm->next_out += left; 1760 s->strm->avail_out -= left; 1761 s->strm->total_out += left; 1762 s->block_start += left; 1763 len -= left; 1764 } 1765 1766 /* Copy uncompressed bytes directly from next_in to next_out, updating 1767 * the check value. 1768 */ 1769 if (len) { 1770 read_buf(s->strm, s->strm->next_out, len); 1771 s->strm->next_out += len; 1772 s->strm->avail_out -= len; 1773 s->strm->total_out += len; 1774 } 1775 } while (last == 0); 1776 1777 /* Update the sliding window with the last s->w_size bytes of the copied 1778 * data, or append all of the copied data to the existing window if less 1779 * than s->w_size bytes were copied. Also update the number of bytes to 1780 * insert in the hash tables, in the event that deflateParams() switches to 1781 * a non-zero compression level. 1782 */ 1783 used -= s->strm->avail_in; /* number of input bytes directly copied */ 1784 if (used) { 1785 /* If any input was used, then no unused input remains in the window, 1786 * therefore s->block_start == s->strstart. 1787 */ 1788 if (used >= s->w_size) { /* supplant the previous history */ 1789 s->matches = 2; /* clear hash */ 1790 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size); 1791 s->strstart = s->w_size; 1792 s->insert = s->strstart; 1793 } 1794 else { 1795 if (s->window_size - s->strstart <= used) { 1796 /* Slide the window down. */ 1797 s->strstart -= s->w_size; 1798 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1799 if (s->matches < 2) 1800 s->matches++; /* add a pending slide_hash() */ 1801 if (s->insert > s->strstart) 1802 s->insert = s->strstart; 1803 } 1804 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used); 1805 s->strstart += used; 1806 s->insert += MIN(used, s->w_size - s->insert); 1807 } 1808 s->block_start = s->strstart; 1809 } 1810 if (s->high_water < s->strstart) 1811 s->high_water = s->strstart; 1812 1813 /* If the last block was written to next_out, then done. */ 1814 if (last) 1815 return finish_done; 1816 1817 /* If flushing and all input has been consumed, then done. */ 1818 if (flush != Z_NO_FLUSH && flush != Z_FINISH && 1819 s->strm->avail_in == 0 && (long)s->strstart == s->block_start) 1820 return block_done; 1821 1822 /* Fill the window with any remaining input. */ 1823 have = s->window_size - s->strstart; 1824 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) { 1825 /* Slide the window down. */ 1826 s->block_start -= s->w_size; 1827 s->strstart -= s->w_size; 1828 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1829 if (s->matches < 2) 1830 s->matches++; /* add a pending slide_hash() */ 1831 have += s->w_size; /* more space now */ 1832 if (s->insert > s->strstart) 1833 s->insert = s->strstart; 1834 } 1835 if (have > s->strm->avail_in) 1836 have = s->strm->avail_in; 1837 if (have) { 1838 read_buf(s->strm, s->window + s->strstart, have); 1839 s->strstart += have; 1840 s->insert += MIN(have, s->w_size - s->insert); 1841 } 1842 if (s->high_water < s->strstart) 1843 s->high_water = s->strstart; 1844 1845 /* There was not enough avail_out to write a complete worthy or flushed 1846 * stored block to next_out. Write a stored block to pending instead, if we 1847 * have enough input for a worthy block, or if flushing and there is enough 1848 * room for the remaining input as a stored block in the pending buffer. 1849 */ 1850 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1851 /* maximum stored block length that will fit in pending: */ 1852 have = MIN(s->pending_buf_size - have, MAX_STORED); 1853 min_block = MIN(have, s->w_size); 1854 left = s->strstart - s->block_start; 1855 if (left >= min_block || 1856 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH && 1857 s->strm->avail_in == 0 && left <= have)) { 1858 len = MIN(left, have); 1859 last = flush == Z_FINISH && s->strm->avail_in == 0 && 1860 len == left ? 1 : 0; 1861 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last); 1862 s->block_start += len; 1863 flush_pending(s->strm); 1864 } 1865 1866 /* We've done all we can with the available input and output. */ 1867 return last ? finish_started : need_more; 1868 } 1869 1870 /* =========================================================================== 1871 * Compress as much as possible from the input stream, return the current 1872 * block state. 1873 * This function does not perform lazy evaluation of matches and inserts 1874 * new strings in the dictionary only for unmatched strings or for short 1875 * matches. It is used only for the fast compression options. 1876 */ 1877 local block_state deflate_fast( 1878 deflate_state *s, 1879 int flush) 1880 { 1881 IPos hash_head; /* head of the hash chain */ 1882 int bflush; /* set if current block must be flushed */ 1883 1884 for (;;) { 1885 /* Make sure that we always have enough lookahead, except 1886 * at the end of the input file. We need MAX_MATCH bytes 1887 * for the next match, plus MIN_MATCH bytes to insert the 1888 * string following the next match. 1889 */ 1890 if (s->lookahead < MIN_LOOKAHEAD) { 1891 fill_window(s); 1892 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1893 return need_more; 1894 } 1895 if (s->lookahead == 0) break; /* flush the current block */ 1896 } 1897 1898 /* Insert the string window[strstart .. strstart + 2] in the 1899 * dictionary, and set hash_head to the head of the hash chain: 1900 */ 1901 hash_head = NIL; 1902 if (s->lookahead >= MIN_MATCH) { 1903 INSERT_STRING(s, s->strstart, hash_head); 1904 } 1905 1906 /* Find the longest match, discarding those <= prev_length. 1907 * At this point we have always match_length < MIN_MATCH 1908 */ 1909 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1910 /* To simplify the code, we prevent matches with the string 1911 * of window index 0 (in particular we have to avoid a match 1912 * of the string with itself at the start of the input file). 1913 */ 1914 s->match_length = longest_match (s, hash_head); 1915 /* longest_match() sets match_start */ 1916 } 1917 if (s->match_length >= MIN_MATCH) { 1918 check_match(s, s->strstart, s->match_start, s->match_length); 1919 1920 _tr_tally_dist(s, s->strstart - s->match_start, 1921 s->match_length - MIN_MATCH, bflush); 1922 1923 s->lookahead -= s->match_length; 1924 1925 /* Insert new strings in the hash table only if the match length 1926 * is not too large. This saves time but degrades compression. 1927 */ 1928 #ifndef FASTEST 1929 if (s->match_length <= s->max_insert_length && 1930 s->lookahead >= MIN_MATCH) { 1931 s->match_length--; /* string at strstart already in table */ 1932 do { 1933 s->strstart++; 1934 INSERT_STRING(s, s->strstart, hash_head); 1935 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1936 * always MIN_MATCH bytes ahead. 1937 */ 1938 } while (--s->match_length != 0); 1939 s->strstart++; 1940 } else 1941 #endif 1942 { 1943 s->strstart += s->match_length; 1944 s->match_length = 0; 1945 s->ins_h = s->window[s->strstart]; 1946 UPDATE_HASH(s, s->ins_h, s->window[s->strstart + 1]); 1947 #if MIN_MATCH != 3 1948 Call UPDATE_HASH() MIN_MATCH-3 more times 1949 #endif 1950 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1951 * matter since it will be recomputed at next deflate call. 1952 */ 1953 } 1954 } else { 1955 /* No match, output a literal byte */ 1956 Tracevv((stderr,"%c", s->window[s->strstart])); 1957 _tr_tally_lit(s, s->window[s->strstart], bflush); 1958 s->lookahead--; 1959 s->strstart++; 1960 } 1961 if (bflush) FLUSH_BLOCK(s, 0); 1962 } 1963 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1964 if (flush == Z_FINISH) { 1965 FLUSH_BLOCK(s, 1); 1966 return finish_done; 1967 } 1968 if (s->sym_next) 1969 FLUSH_BLOCK(s, 0); 1970 return block_done; 1971 } 1972 1973 #ifndef FASTEST 1974 /* =========================================================================== 1975 * Same as above, but achieves better compression. We use a lazy 1976 * evaluation for matches: a match is finally adopted only if there is 1977 * no better match at the next window position. 1978 */ 1979 local block_state deflate_slow( 1980 deflate_state *s, 1981 int flush) 1982 { 1983 IPos hash_head; /* head of hash chain */ 1984 int bflush; /* set if current block must be flushed */ 1985 1986 /* Process the input block. */ 1987 for (;;) { 1988 /* Make sure that we always have enough lookahead, except 1989 * at the end of the input file. We need MAX_MATCH bytes 1990 * for the next match, plus MIN_MATCH bytes to insert the 1991 * string following the next match. 1992 */ 1993 if (s->lookahead < MIN_LOOKAHEAD) { 1994 fill_window(s); 1995 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1996 return need_more; 1997 } 1998 if (s->lookahead == 0) break; /* flush the current block */ 1999 } 2000 2001 /* Insert the string window[strstart .. strstart + 2] in the 2002 * dictionary, and set hash_head to the head of the hash chain: 2003 */ 2004 hash_head = NIL; 2005 if (s->lookahead >= MIN_MATCH) { 2006 INSERT_STRING(s, s->strstart, hash_head); 2007 } 2008 2009 /* Find the longest match, discarding those <= prev_length. 2010 */ 2011 s->prev_length = s->match_length, s->prev_match = s->match_start; 2012 s->match_length = MIN_MATCH-1; 2013 2014 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 2015 s->strstart - hash_head <= MAX_DIST(s)) { 2016 /* To simplify the code, we prevent matches with the string 2017 * of window index 0 (in particular we have to avoid a match 2018 * of the string with itself at the start of the input file). 2019 */ 2020 s->match_length = longest_match (s, hash_head); 2021 /* longest_match() sets match_start */ 2022 2023 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 2024 #if TOO_FAR <= 32767 2025 || (s->match_length == MIN_MATCH && 2026 s->strstart - s->match_start > TOO_FAR) 2027 #endif 2028 )) { 2029 2030 /* If prev_match is also MIN_MATCH, match_start is garbage 2031 * but we will ignore the current match anyway. 2032 */ 2033 s->match_length = MIN_MATCH-1; 2034 } 2035 } 2036 /* If there was a match at the previous step and the current 2037 * match is not better, output the previous match: 2038 */ 2039 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 2040 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 2041 /* Do not insert strings in hash table beyond this. */ 2042 2043 check_match(s, s->strstart - 1, s->prev_match, s->prev_length); 2044 2045 _tr_tally_dist(s, s->strstart - 1 - s->prev_match, 2046 s->prev_length - MIN_MATCH, bflush); 2047 2048 /* Insert in hash table all strings up to the end of the match. 2049 * strstart - 1 and strstart are already inserted. If there is not 2050 * enough lookahead, the last two strings are not inserted in 2051 * the hash table. 2052 */ 2053 s->lookahead -= s->prev_length - 1; 2054 s->prev_length -= 2; 2055 do { 2056 if (++s->strstart <= max_insert) { 2057 INSERT_STRING(s, s->strstart, hash_head); 2058 } 2059 } while (--s->prev_length != 0); 2060 s->match_available = 0; 2061 s->match_length = MIN_MATCH-1; 2062 s->strstart++; 2063 2064 if (bflush) FLUSH_BLOCK(s, 0); 2065 2066 } else if (s->match_available) { 2067 /* If there was no match at the previous position, output a 2068 * single literal. If there was a match but the current match 2069 * is longer, truncate the previous match to a single literal. 2070 */ 2071 Tracevv((stderr,"%c", s->window[s->strstart - 1])); 2072 _tr_tally_lit(s, s->window[s->strstart - 1], bflush); 2073 if (bflush) { 2074 FLUSH_BLOCK_ONLY(s, 0); 2075 } 2076 s->strstart++; 2077 s->lookahead--; 2078 if (s->strm->avail_out == 0) return need_more; 2079 } else { 2080 /* There is no previous match to compare with, wait for 2081 * the next step to decide. 2082 */ 2083 s->match_available = 1; 2084 s->strstart++; 2085 s->lookahead--; 2086 } 2087 } 2088 Assert (flush != Z_NO_FLUSH, "no flush?"); 2089 if (s->match_available) { 2090 Tracevv((stderr,"%c", s->window[s->strstart - 1])); 2091 _tr_tally_lit(s, s->window[s->strstart - 1], bflush); 2092 s->match_available = 0; 2093 } 2094 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 2095 if (flush == Z_FINISH) { 2096 FLUSH_BLOCK(s, 1); 2097 return finish_done; 2098 } 2099 if (s->sym_next) 2100 FLUSH_BLOCK(s, 0); 2101 return block_done; 2102 } 2103 #endif /* FASTEST */ 2104 2105 /* =========================================================================== 2106 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 2107 * one. Do not maintain a hash table. (It will be regenerated if this run of 2108 * deflate switches away from Z_RLE.) 2109 */ 2110 local block_state deflate_rle( 2111 deflate_state *s, 2112 int flush) 2113 { 2114 int bflush; /* set if current block must be flushed */ 2115 uInt prev; /* byte at distance one to match */ 2116 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 2117 2118 for (;;) { 2119 /* Make sure that we always have enough lookahead, except 2120 * at the end of the input file. We need MAX_MATCH bytes 2121 * for the longest run, plus one for the unrolled loop. 2122 */ 2123 if (s->lookahead <= MAX_MATCH) { 2124 fill_window(s); 2125 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 2126 return need_more; 2127 } 2128 if (s->lookahead == 0) break; /* flush the current block */ 2129 } 2130 2131 /* See how many times the previous byte repeats */ 2132 s->match_length = 0; 2133 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 2134 scan = s->window + s->strstart - 1; 2135 prev = *scan; 2136 if (prev == *++scan && prev == *++scan && prev == *++scan) { 2137 strend = s->window + s->strstart + MAX_MATCH; 2138 do { 2139 } while (prev == *++scan && prev == *++scan && 2140 prev == *++scan && prev == *++scan && 2141 prev == *++scan && prev == *++scan && 2142 prev == *++scan && prev == *++scan && 2143 scan < strend); 2144 s->match_length = MAX_MATCH - (uInt)(strend - scan); 2145 if (s->match_length > s->lookahead) 2146 s->match_length = s->lookahead; 2147 } 2148 Assert(scan <= s->window + (uInt)(s->window_size - 1), 2149 "wild scan"); 2150 } 2151 2152 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 2153 if (s->match_length >= MIN_MATCH) { 2154 check_match(s, s->strstart, s->strstart - 1, s->match_length); 2155 2156 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 2157 2158 s->lookahead -= s->match_length; 2159 s->strstart += s->match_length; 2160 s->match_length = 0; 2161 } else { 2162 /* No match, output a literal byte */ 2163 Tracevv((stderr,"%c", s->window[s->strstart])); 2164 _tr_tally_lit(s, s->window[s->strstart], bflush); 2165 s->lookahead--; 2166 s->strstart++; 2167 } 2168 if (bflush) FLUSH_BLOCK(s, 0); 2169 } 2170 s->insert = 0; 2171 if (flush == Z_FINISH) { 2172 FLUSH_BLOCK(s, 1); 2173 return finish_done; 2174 } 2175 if (s->sym_next) 2176 FLUSH_BLOCK(s, 0); 2177 return block_done; 2178 } 2179 2180 /* =========================================================================== 2181 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 2182 * (It will be regenerated if this run of deflate switches away from Huffman.) 2183 */ 2184 local block_state deflate_huff( 2185 deflate_state *s, 2186 int flush) 2187 { 2188 int bflush; /* set if current block must be flushed */ 2189 2190 for (;;) { 2191 /* Make sure that we have a literal to write. */ 2192 if (s->lookahead == 0) { 2193 fill_window(s); 2194 if (s->lookahead == 0) { 2195 if (flush == Z_NO_FLUSH) 2196 return need_more; 2197 break; /* flush the current block */ 2198 } 2199 } 2200 2201 /* Output a literal byte */ 2202 s->match_length = 0; 2203 Tracevv((stderr,"%c", s->window[s->strstart])); 2204 _tr_tally_lit(s, s->window[s->strstart], bflush); 2205 s->lookahead--; 2206 s->strstart++; 2207 if (bflush) FLUSH_BLOCK(s, 0); 2208 } 2209 s->insert = 0; 2210 if (flush == Z_FINISH) { 2211 FLUSH_BLOCK(s, 1); 2212 return finish_done; 2213 } 2214 if (s->sym_next) 2215 FLUSH_BLOCK(s, 0); 2216 return block_done; 2217 } 2218