1/* deflate.c -- compress data using the deflation algorithm 2 * Copyright (C) 1995-2010 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://www.ietf.org/rfc/rfc1951.txt 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/* \param (#) $Id$ */ 51 52#include "deflate.h" 53 54const char deflate_copyright[] = 55 " deflate 1.2.5 Copyright 1995-2010 Jean-loup Gailly and Mark Adler "; 56/* 57 If you use the zlib library in a product, an acknowledgment is welcome 58 in the documentation of your product. If for some reason you cannot 59 include such an acknowledgment, I would appreciate that you keep this 60 copyright string in the executable of your product. 61 */ 62 63/* =========================================================================== 64 * Function prototypes. 65 */ 66typedef enum { 67 need_more, /* block not completed, need more input or more output */ 68 block_done, /* block flush performed */ 69 finish_started, /* finish started, need only more output at next deflate */ 70 finish_done /* finish done, accept no more input or output */ 71} block_state; 72 73typedef block_state (*compress_func) OF((deflate_state *s, int flush)); 74/* Compression function. Returns the block state after the call. */ 75 76local void fill_window OF((deflate_state *s)); 77local block_state deflate_stored OF((deflate_state *s, int flush)); 78local block_state deflate_fast OF((deflate_state *s, int flush)); 79#ifndef FASTEST 80local block_state deflate_slow OF((deflate_state *s, int flush)); 81#endif 82local block_state deflate_rle OF((deflate_state *s, int flush)); 83local block_state deflate_huff OF((deflate_state *s, int flush)); 84local void lm_init OF((deflate_state *s)); 85local void putShortMSB OF((deflate_state *s, uInt b)); 86local void flush_pending OF((z_streamp strm)); 87local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size)); 88#ifdef ASMV 89 void match_init OF((void)); /* asm code initialization */ 90 uInt longest_match OF((deflate_state *s, IPos cur_match)); 91#else 92local uInt longest_match OF((deflate_state *s, IPos cur_match)); 93#endif 94 95#ifdef DEBUG 96local void check_match OF((deflate_state *s, IPos start, IPos match, 97 int length)); 98#endif 99 100/* =========================================================================== 101 * Local data 102 */ 103 104#define NIL 0 105/* Tail of hash chains */ 106 107#ifndef TOO_FAR 108# define TOO_FAR 4096 109#endif 110/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ 111 112/* Values for max_lazy_match, good_match and max_chain_length, depending on 113 * the desired pack level (0..9). The values given below have been tuned to 114 * exclude worst case performance for pathological files. Better values may be 115 * found for specific files. 116 */ 117typedef struct config_s { 118 ush good_length; /* reduce lazy search above this match length */ 119 ush max_lazy; /* do not perform lazy search above this match length */ 120 ush nice_length; /* quit search above this match length */ 121 ush max_chain; 122 compress_func func; 123} config; 124 125#ifdef FASTEST 126local const config configuration_table[2] = { 127/* good lazy nice chain */ 128/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 129/* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ 130#else 131local const config configuration_table[10] = { 132/* good lazy nice chain */ 133/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 134/* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ 135/* 2 */ {4, 5, 16, 8, deflate_fast}, 136/* 3 */ {4, 6, 32, 32, deflate_fast}, 137 138/* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ 139/* 5 */ {8, 16, 32, 32, deflate_slow}, 140/* 6 */ {8, 16, 128, 128, deflate_slow}, 141/* 7 */ {8, 32, 128, 256, deflate_slow}, 142/* 8 */ {32, 128, 258, 1024, deflate_slow}, 143/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ 144#endif 145 146/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 147 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different 148 * meaning. 149 */ 150 151#define EQUAL 0 152/* result of memcmp for equal strings */ 153 154#ifndef NO_DUMMY_DECL 155struct static_tree_desc_s {int dummy;}; /* for buggy compilers */ 156#endif 157 158/* =========================================================================== 159 * Update a hash value with the given input byte 160 * IN assertion: all calls to to UPDATE_HASH are made with consecutive 161 * input characters, so that a running hash key can be computed from the 162 * previous key instead of complete recalculation each time. 163 */ 164#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask) 165 166 167/* =========================================================================== 168 * Insert string str in the dictionary and set match_head to the previous head 169 * of the hash chain (the most recent string with same hash key). Return 170 * the previous length of the hash chain. 171 * If this file is compiled with -DFASTEST, the compression level is forced 172 * to 1, and no hash chains are maintained. 173 * IN assertion: all calls to to INSERT_STRING are made with consecutive 174 * input characters and the first MIN_MATCH bytes of str are valid 175 * (except for the last MIN_MATCH-1 bytes of the input file). 176 */ 177#ifdef FASTEST 178#define INSERT_STRING(s, str, match_head) \ 179 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 180 match_head = s->head[s->ins_h], \ 181 s->head[s->ins_h] = (Pos)(str)) 182#else 183#define INSERT_STRING(s, str, match_head) \ 184 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 185 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ 186 s->head[s->ins_h] = (Pos)(str)) 187#endif 188 189/* =========================================================================== 190 * Initialize the hash table (avoiding 64K overflow for 16 bit systems). 191 * prev[] will be initialized on the fly. 192 */ 193#define CLEAR_HASH(s) \ 194 s->head[s->hash_size-1] = NIL; \ 195 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head)); 196 197/* ========================================================================= */ 198int ZEXPORT deflateInit_(strm, level, version, stream_size) 199 z_streamp strm; 200 int level; 201 const char *version; 202 int stream_size; 203{ 204 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, 205 Z_DEFAULT_STRATEGY, version, stream_size); 206 /* To do: ignore strm->next_in if we use it as window */ 207} 208 209/* ========================================================================= */ 210int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy, 211 version, stream_size) 212 z_streamp strm; 213 int level; 214 int method; 215 int windowBits; 216 int memLevel; 217 int strategy; 218 const char *version; 219 int stream_size; 220{ 221 deflate_state *s; 222 int wrap = 1; 223 static const char my_version[] = ZLIB_VERSION; 224 225 if (version == Z_NULL || version[0] != my_version[0] || 226 stream_size != sizeof(z_stream)) { 227 return Z_VERSION_ERROR; 228 } 229 if (strm == Z_NULL) return Z_STREAM_ERROR; 230 231 strm->msg = Z_NULL; 232 if (strm->zalloc == (alloc_func)0) { 233 strm->zalloc = zcalloc; 234 strm->opaque = (voidpf)0; 235 } 236 if (strm->zfree == (free_func)0) strm->zfree = zcfree; 237 238#ifdef FASTEST 239 if (level != 0) level = 1; 240#else 241 if (level == Z_DEFAULT_COMPRESSION) level = 6; 242#endif 243 244 if (windowBits < 0) { /* suppress zlib wrapper */ 245 wrap = 0; 246 windowBits = -windowBits; 247 } 248#ifdef GZIP 249 else if (windowBits > 15) { 250 wrap = 2; /* write gzip wrapper instead */ 251 windowBits -= 16; 252 } 253#endif 254 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 255 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 256 strategy < 0 || strategy > Z_FIXED) { 257 return Z_STREAM_ERROR; 258 } 259 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 260 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 261 if (s == Z_NULL) return Z_MEM_ERROR; 262 strm->state = (struct internal_state FAR *)s; 263 s->strm = strm; 264 265 s->wrap = wrap; 266 s->gzhead = Z_NULL; 267 s->w_bits = windowBits; 268 s->w_size = 1 << s->w_bits; 269 s->w_mask = s->w_size - 1; 270 271 s->hash_bits = memLevel + 7; 272 s->hash_size = 1 << s->hash_bits; 273 s->hash_mask = s->hash_size - 1; 274 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); 275 276 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 277 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 278 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 279 280 s->high_water = 0; /* nothing written to s->window yet */ 281 282 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 283 284 /* We overlay pending_buf and sym_buf. This works since the average size 285 * for length/distance pairs over any compressed block is assured to be 31 286 * bits or less. 287 * 288 * Analysis: The longest fixed codes are a length code of 8 bits plus 5 289 * extra bits, for lengths 131 to 257. The longest fixed distance codes are 290 * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest 291 * possible fixed-codes length/distance pair is then 31 bits total. 292 * 293 * sym_buf starts one-fourth of the way into pending_buf. So there are 294 * three bytes in sym_buf for every four bytes in pending_buf. Each symbol 295 * in sym_buf is three bytes -- two for the distance and one for the 296 * literal/length. As each symbol is consumed, the pointer to the next 297 * sym_buf value to read moves forward three bytes. From that symbol, up to 298 * 31 bits are written to pending_buf. The closest the written pending_buf 299 * bits gets to the next sym_buf symbol to read is just before the last 300 * code is written. At that time, 31*(n-2) bits have been written, just 301 * after 24*(n-2) bits have been consumed from sym_buf. sym_buf starts at 302 * 8*n bits into pending_buf. (Note that the symbol buffer fills when n-1 303 * symbols are written.) The closest the writing gets to what is unread is 304 * then n+14 bits. Here n is lit_bufsize, which is 16384 by default, and 305 * can range from 128 to 32768. 306 * 307 * Therefore, at a minimum, there are 142 bits of space between what is 308 * written and what is read in the overlain buffers, so the symbols cannot 309 * be overwritten by the compressed data. That space is actually 139 bits, 310 * due to the three-bit fixed-code block header. 311 * 312 * That covers the case where either Z_FIXED is specified, forcing fixed 313 * codes, or when the use of fixed codes is chosen, because that choice 314 * results in a smaller compressed block than dynamic codes. That latter 315 * condition then assures that the above analysis also covers all dynamic 316 * blocks. A dynamic-code block will only be chosen to be emitted if it has 317 * fewer bits than a fixed-code block would for the same set of symbols. 318 * Therefore its average symbol length is assured to be less than 31. So 319 * the compressed data for a dynamic block also cannot overwrite the 320 * symbols from which it is being constructed. 321 */ 322 323 s->pending_buf = (uchf *) ZALLOC(strm, s->lit_bufsize, 4); 324 s->pending_buf_size = (ulg)s->lit_bufsize * 4; 325 326 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 327 s->pending_buf == Z_NULL) { 328 s->status = FINISH_STATE; 329 strm->msg = (char*)ERR_MSG(Z_MEM_ERROR); 330 deflateEnd (strm); 331 return Z_MEM_ERROR; 332 } 333 s->sym_buf = s->pending_buf + s->lit_bufsize; 334 s->sym_end = (s->lit_bufsize - 1) * 3; 335 /* We avoid equality with lit_bufsize*3 because of wraparound at 64K 336 * on 16 bit machines and because stored blocks are restricted to 337 * 64K-1 bytes. 338 */ 339 340 s->level = level; 341 s->strategy = strategy; 342 s->method = (Byte)method; 343 344 return deflateReset(strm); 345} 346 347/* ========================================================================= */ 348int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength) 349 z_streamp strm; 350 const Bytef *dictionary; 351 uInt dictLength; 352{ 353 deflate_state *s; 354 uInt length = dictLength; 355 uInt n; 356 IPos hash_head = 0; 357 358 if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL || 359 strm->state->wrap == 2 || 360 (strm->state->wrap == 1 && strm->state->status != INIT_STATE)) 361 return Z_STREAM_ERROR; 362 363 s = strm->state; 364 if (s->wrap) 365 strm->adler = adler32(strm->adler, dictionary, dictLength); 366 367 if (length < MIN_MATCH) return Z_OK; 368 if (length > s->w_size) { 369 length = s->w_size; 370 dictionary += dictLength - length; /* use the tail of the dictionary */ 371 } 372 zmemcpy(s->window, dictionary, length); 373 s->strstart = length; 374 s->block_start = (long)length; 375 376 /* Insert all strings in the hash table (except for the last two bytes). 377 * s->lookahead stays null, so s->ins_h will be recomputed at the next 378 * call of fill_window. 379 */ 380 s->ins_h = s->window[0]; 381 UPDATE_HASH(s, s->ins_h, s->window[1]); 382 for (n = 0; n <= length - MIN_MATCH; n++) { 383 INSERT_STRING(s, n, hash_head); 384 } 385 if (hash_head) hash_head = 0; /* to make compiler happy */ 386 return Z_OK; 387} 388 389/* ========================================================================= */ 390int ZEXPORT deflateReset (strm) 391 z_streamp strm; 392{ 393 deflate_state *s; 394 395 if (strm == Z_NULL || strm->state == Z_NULL || 396 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) { 397 return Z_STREAM_ERROR; 398 } 399 400 strm->total_in = strm->total_out = 0; 401 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 402 strm->data_type = Z_UNKNOWN; 403 404 s = (deflate_state *)strm->state; 405 s->pending = 0; 406 s->pending_out = s->pending_buf; 407 408 if (s->wrap < 0) { 409 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 410 } 411 s->status = s->wrap ? INIT_STATE : BUSY_STATE; 412 strm->adler = 413#ifdef GZIP 414 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 415#endif 416 adler32(0L, Z_NULL, 0); 417 s->last_flush = Z_NO_FLUSH; 418 419 _tr_init(s); 420 lm_init(s); 421 422 return Z_OK; 423} 424 425/* ========================================================================= */ 426int ZEXPORT deflateSetHeader (strm, head) 427 z_streamp strm; 428 gz_headerp head; 429{ 430 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 431 if (strm->state->wrap != 2) return Z_STREAM_ERROR; 432 strm->state->gzhead = head; 433 return Z_OK; 434} 435 436/* ========================================================================= */ 437int ZEXPORT deflatePending (strm, pending, bits) 438 unsigned *pending; 439 int *bits; 440 z_streamp strm; 441{ 442 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 443 *pending = strm->state->pending; 444 *bits = strm->state->bi_valid; 445 return Z_OK; 446} 447 448/* ========================================================================= */ 449int ZEXPORT deflatePrime (strm, bits, value) 450 z_streamp strm; 451 int bits; 452 int value; 453{ 454 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 455 strm->state->bi_valid = bits; 456 strm->state->bi_buf = (ush)(value & ((1 << bits) - 1)); 457 return Z_OK; 458} 459 460/* ========================================================================= */ 461int ZEXPORT deflateParams(strm, level, strategy) 462 z_streamp strm; 463 int level; 464 int strategy; 465{ 466 deflate_state *s; 467 compress_func func; 468 int err = Z_OK; 469 470 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 471 s = strm->state; 472 473#ifdef FASTEST 474 if (level != 0) level = 1; 475#else 476 if (level == Z_DEFAULT_COMPRESSION) level = 6; 477#endif 478 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 479 return Z_STREAM_ERROR; 480 } 481 func = configuration_table[s->level].func; 482 483 if ((strategy != s->strategy || func != configuration_table[level].func) && 484 strm->total_in != 0) { 485 /* Flush the last buffer: */ 486 err = deflate(strm, Z_BLOCK); 487 } 488 if (s->level != level) { 489 s->level = level; 490 s->max_lazy_match = configuration_table[level].max_lazy; 491 s->good_match = configuration_table[level].good_length; 492 s->nice_match = configuration_table[level].nice_length; 493 s->max_chain_length = configuration_table[level].max_chain; 494 } 495 s->strategy = strategy; 496 return err; 497} 498 499/* ========================================================================= */ 500int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain) 501 z_streamp strm; 502 int good_length; 503 int max_lazy; 504 int nice_length; 505 int max_chain; 506{ 507 deflate_state *s; 508 509 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 510 s = strm->state; 511 s->good_match = good_length; 512 s->max_lazy_match = max_lazy; 513 s->nice_match = nice_length; 514 s->max_chain_length = max_chain; 515 return Z_OK; 516} 517 518/* ========================================================================= 519 * For the default windowBits of 15 and memLevel of 8, this function returns 520 * a close to exact, as well as small, upper bound on the compressed size. 521 * They are coded as constants here for a reason--if the #define's are 522 * changed, then this function needs to be changed as well. The return 523 * value for 15 and 8 only works for those exact settings. 524 * 525 * For any setting other than those defaults for windowBits and memLevel, 526 * the value returned is a conservative worst case for the maximum expansion 527 * resulting from using fixed blocks instead of stored blocks, which deflate 528 * can emit on compressed data for some combinations of the parameters. 529 * 530 * This function could be more sophisticated to provide closer upper bounds for 531 * every combination of windowBits and memLevel. But even the conservative 532 * upper bound of about 14% expansion does not seem onerous for output buffer 533 * allocation. 534 */ 535uLong ZEXPORT deflateBound(strm, sourceLen) 536 z_streamp strm; 537 uLong sourceLen; 538{ 539 deflate_state *s; 540 uLong complen, wraplen; 541 Bytef *str; 542 543 /* conservative upper bound for compressed data */ 544 complen = sourceLen + 545 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5; 546 547 /* if can't get parameters, return conservative bound plus zlib wrapper */ 548 if (strm == Z_NULL || strm->state == Z_NULL) 549 return complen + 6; 550 551 /* compute wrapper length */ 552 s = strm->state; 553 switch (s->wrap) { 554 case 0: /* raw deflate */ 555 wraplen = 0; 556 break; 557 case 1: /* zlib wrapper */ 558 wraplen = 6 + (s->strstart ? 4 : 0); 559 break; 560 case 2: /* gzip wrapper */ 561 wraplen = 18; 562 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 563 if (s->gzhead->extra != Z_NULL) 564 wraplen += 2 + s->gzhead->extra_len; 565 str = s->gzhead->name; 566 if (str != Z_NULL) 567 do { 568 wraplen++; 569 } while (*str++); 570 str = s->gzhead->comment; 571 if (str != Z_NULL) 572 do { 573 wraplen++; 574 } while (*str++); 575 if (s->gzhead->hcrc) 576 wraplen += 2; 577 } 578 break; 579 default: /* for compiler happiness */ 580 wraplen = 6; 581 } 582 583 /* if not default parameters, return conservative bound */ 584 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 585 return complen + wraplen; 586 587 /* default settings: return tight bound for that case */ 588 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 589 (sourceLen >> 25) + 13 - 6 + wraplen; 590} 591 592/* ========================================================================= 593 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 594 * IN assertion: the stream state is correct and there is enough room in 595 * pending_buf. 596 */ 597local void putShortMSB (s, b) 598 deflate_state *s; 599 uInt b; 600{ 601 put_byte(s, (Byte)(b >> 8)); 602 put_byte(s, (Byte)(b & 0xff)); 603} 604 605/* ========================================================================= 606 * Flush as much pending output as possible. All deflate() output goes 607 * through this function so some applications may wish to modify it 608 * to avoid allocating a large strm->next_out buffer and copying into it. 609 * (See also read_buf()). 610 */ 611local void flush_pending(strm) 612 z_streamp strm; 613{ 614 unsigned len = strm->state->pending; 615 616 if (len > strm->avail_out) len = strm->avail_out; 617 if (len == 0) return; 618 619 zmemcpy(strm->next_out, strm->state->pending_out, len); 620 strm->next_out += len; 621 strm->state->pending_out += len; 622 strm->total_out += len; 623 strm->avail_out -= len; 624 strm->state->pending -= len; 625 if (strm->state->pending == 0) { 626 strm->state->pending_out = strm->state->pending_buf; 627 } 628} 629 630/* ========================================================================= */ 631int ZEXPORT deflate (strm, flush) 632 z_streamp strm; 633 int flush; 634{ 635 int old_flush; /* value of flush param for previous deflate call */ 636 deflate_state *s; 637 638 if (strm == Z_NULL || strm->state == Z_NULL || 639 flush > Z_BLOCK || flush < 0) { 640 return Z_STREAM_ERROR; 641 } 642 s = strm->state; 643 644 if (strm->next_out == Z_NULL || 645 (strm->next_in == Z_NULL && strm->avail_in != 0) || 646 (s->status == FINISH_STATE && flush != Z_FINISH)) { 647 ERR_RETURN(strm, Z_STREAM_ERROR); 648 } 649 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 650 651 s->strm = strm; /* just in case */ 652 old_flush = s->last_flush; 653 s->last_flush = flush; 654 655 /* Write the header */ 656 if (s->status == INIT_STATE) { 657#ifdef GZIP 658 if (s->wrap == 2) { 659 strm->adler = crc32(0L, Z_NULL, 0); 660 put_byte(s, 31); 661 put_byte(s, 139); 662 put_byte(s, 8); 663 if (s->gzhead == Z_NULL) { 664 put_byte(s, 0); 665 put_byte(s, 0); 666 put_byte(s, 0); 667 put_byte(s, 0); 668 put_byte(s, 0); 669 put_byte(s, s->level == 9 ? 2 : 670 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 671 4 : 0)); 672 put_byte(s, OS_CODE); 673 s->status = BUSY_STATE; 674 } 675 else { 676 put_byte(s, (s->gzhead->text ? 1 : 0) + 677 (s->gzhead->hcrc ? 2 : 0) + 678 (s->gzhead->extra == Z_NULL ? 0 : 4) + 679 (s->gzhead->name == Z_NULL ? 0 : 8) + 680 (s->gzhead->comment == Z_NULL ? 0 : 16) 681 ); 682 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 683 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 684 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 685 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 686 put_byte(s, s->level == 9 ? 2 : 687 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 688 4 : 0)); 689 put_byte(s, s->gzhead->os & 0xff); 690 if (s->gzhead->extra != Z_NULL) { 691 put_byte(s, s->gzhead->extra_len & 0xff); 692 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 693 } 694 if (s->gzhead->hcrc) 695 strm->adler = crc32(strm->adler, s->pending_buf, 696 s->pending); 697 s->gzindex = 0; 698 s->status = EXTRA_STATE; 699 } 700 } 701 else 702#endif 703 { 704 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; 705 uInt level_flags; 706 707 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 708 level_flags = 0; 709 else if (s->level < 6) 710 level_flags = 1; 711 else if (s->level == 6) 712 level_flags = 2; 713 else 714 level_flags = 3; 715 header |= (level_flags << 6); 716 if (s->strstart != 0) header |= PRESET_DICT; 717 header += 31 - (header % 31); 718 719 s->status = BUSY_STATE; 720 putShortMSB(s, header); 721 722 /* Save the adler32 of the preset dictionary: */ 723 if (s->strstart != 0) { 724 putShortMSB(s, (uInt)(strm->adler >> 16)); 725 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 726 } 727 strm->adler = adler32(0L, Z_NULL, 0); 728 } 729 } 730#ifdef GZIP 731 if (s->status == EXTRA_STATE) { 732 if (s->gzhead->extra != Z_NULL) { 733 uInt beg = s->pending; /* start of bytes to update crc */ 734 735 while (s->gzindex < (s->gzhead->extra_len & 0xffff)) { 736 if (s->pending == s->pending_buf_size) { 737 if (s->gzhead->hcrc && s->pending > beg) 738 strm->adler = crc32(strm->adler, s->pending_buf + beg, 739 s->pending - beg); 740 flush_pending(strm); 741 beg = s->pending; 742 if (s->pending == s->pending_buf_size) 743 break; 744 } 745 put_byte(s, s->gzhead->extra[s->gzindex]); 746 s->gzindex++; 747 } 748 if (s->gzhead->hcrc && s->pending > beg) 749 strm->adler = crc32(strm->adler, s->pending_buf + beg, 750 s->pending - beg); 751 if (s->gzindex == s->gzhead->extra_len) { 752 s->gzindex = 0; 753 s->status = NAME_STATE; 754 } 755 } 756 else 757 s->status = NAME_STATE; 758 } 759 if (s->status == NAME_STATE) { 760 if (s->gzhead->name != Z_NULL) { 761 uInt beg = s->pending; /* start of bytes to update crc */ 762 int val; 763 764 do { 765 if (s->pending == s->pending_buf_size) { 766 if (s->gzhead->hcrc && s->pending > beg) 767 strm->adler = crc32(strm->adler, s->pending_buf + beg, 768 s->pending - beg); 769 flush_pending(strm); 770 beg = s->pending; 771 if (s->pending == s->pending_buf_size) { 772 val = 1; 773 break; 774 } 775 } 776 val = s->gzhead->name[s->gzindex++]; 777 put_byte(s, val); 778 } while (val != 0); 779 if (s->gzhead->hcrc && s->pending > beg) 780 strm->adler = crc32(strm->adler, s->pending_buf + beg, 781 s->pending - beg); 782 if (val == 0) { 783 s->gzindex = 0; 784 s->status = COMMENT_STATE; 785 } 786 } 787 else 788 s->status = COMMENT_STATE; 789 } 790 if (s->status == COMMENT_STATE) { 791 if (s->gzhead->comment != Z_NULL) { 792 uInt beg = s->pending; /* start of bytes to update crc */ 793 int val; 794 795 do { 796 if (s->pending == s->pending_buf_size) { 797 if (s->gzhead->hcrc && s->pending > beg) 798 strm->adler = crc32(strm->adler, s->pending_buf + beg, 799 s->pending - beg); 800 flush_pending(strm); 801 beg = s->pending; 802 if (s->pending == s->pending_buf_size) { 803 val = 1; 804 break; 805 } 806 } 807 val = s->gzhead->comment[s->gzindex++]; 808 put_byte(s, val); 809 } while (val != 0); 810 if (s->gzhead->hcrc && s->pending > beg) 811 strm->adler = crc32(strm->adler, s->pending_buf + beg, 812 s->pending - beg); 813 if (val == 0) 814 s->status = HCRC_STATE; 815 } 816 else 817 s->status = HCRC_STATE; 818 } 819 if (s->status == HCRC_STATE) { 820 if (s->gzhead->hcrc) { 821 if (s->pending + 2 > s->pending_buf_size) 822 flush_pending(strm); 823 if (s->pending + 2 <= s->pending_buf_size) { 824 put_byte(s, (Byte)(strm->adler & 0xff)); 825 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 826 strm->adler = crc32(0L, Z_NULL, 0); 827 s->status = BUSY_STATE; 828 } 829 } 830 else 831 s->status = BUSY_STATE; 832 } 833#endif 834 835 /* Flush as much pending output as possible */ 836 if (s->pending != 0) { 837 flush_pending(strm); 838 if (strm->avail_out == 0) { 839 /* Since avail_out is 0, deflate will be called again with 840 * more output space, but possibly with both pending and 841 * avail_in equal to zero. There won't be anything to do, 842 * but this is not an error situation so make sure we 843 * return OK instead of BUF_ERROR at next call of deflate: 844 */ 845 s->last_flush = -1; 846 return Z_OK; 847 } 848 849 /* Make sure there is something to do and avoid duplicate consecutive 850 * flushes. For repeated and useless calls with Z_FINISH, we keep 851 * returning Z_STREAM_END instead of Z_BUF_ERROR. 852 */ 853 } else if (strm->avail_in == 0 && flush <= old_flush && 854 flush != Z_FINISH) { 855 ERR_RETURN(strm, Z_BUF_ERROR); 856 } 857 858 /* User must not provide more input after the first FINISH: */ 859 if (s->status == FINISH_STATE && strm->avail_in != 0) { 860 ERR_RETURN(strm, Z_BUF_ERROR); 861 } 862 863 /* Start a new block or continue the current one. 864 */ 865 if (strm->avail_in != 0 || s->lookahead != 0 || 866 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 867 block_state bstate; 868 869 bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 870 (s->strategy == Z_RLE ? deflate_rle(s, flush) : 871 (*(configuration_table[s->level].func))(s, flush)); 872 873 if (bstate == finish_started || bstate == finish_done) { 874 s->status = FINISH_STATE; 875 } 876 if (bstate == need_more || bstate == finish_started) { 877 if (strm->avail_out == 0) { 878 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 879 } 880 return Z_OK; 881 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 882 * of deflate should use the same flush parameter to make sure 883 * that the flush is complete. So we don't have to output an 884 * empty block here, this will be done at next call. This also 885 * ensures that for a very small output buffer, we emit at most 886 * one empty block. 887 */ 888 } 889 if (bstate == block_done) { 890 if (flush == Z_PARTIAL_FLUSH) { 891 _tr_align(s); 892 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 893 _tr_stored_block(s, (char*)0, 0L, 0); 894 /* For a full flush, this empty block will be recognized 895 * as a special marker by inflate_sync(). 896 */ 897 if (flush == Z_FULL_FLUSH) { 898 CLEAR_HASH(s); /* forget history */ 899 if (s->lookahead == 0) { 900 s->strstart = 0; 901 s->block_start = 0L; 902 } 903 } 904 } 905 flush_pending(strm); 906 if (strm->avail_out == 0) { 907 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 908 return Z_OK; 909 } 910 } 911 } 912 Assert(strm->avail_out > 0, "bug2"); 913 914 if (flush != Z_FINISH) return Z_OK; 915 if (s->wrap <= 0) return Z_STREAM_END; 916 917 /* Write the trailer */ 918#ifdef GZIP 919 if (s->wrap == 2) { 920 put_byte(s, (Byte)(strm->adler & 0xff)); 921 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 922 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 923 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 924 put_byte(s, (Byte)(strm->total_in & 0xff)); 925 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 926 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 927 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 928 } 929 else 930#endif 931 { 932 putShortMSB(s, (uInt)(strm->adler >> 16)); 933 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 934 } 935 flush_pending(strm); 936 /* If avail_out is zero, the application will call deflate again 937 * to flush the rest. 938 */ 939 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 940 return s->pending != 0 ? Z_OK : Z_STREAM_END; 941} 942 943/* ========================================================================= */ 944int ZEXPORT deflateEnd (strm) 945 z_streamp strm; 946{ 947 int status; 948 949 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 950 951 status = strm->state->status; 952 if (status != INIT_STATE && 953 status != EXTRA_STATE && 954 status != NAME_STATE && 955 status != COMMENT_STATE && 956 status != HCRC_STATE && 957 status != BUSY_STATE && 958 status != FINISH_STATE) { 959 return Z_STREAM_ERROR; 960 } 961 962 /* Deallocate in reverse order of allocations: */ 963 TRY_FREE(strm, strm->state->pending_buf); 964 TRY_FREE(strm, strm->state->head); 965 TRY_FREE(strm, strm->state->prev); 966 TRY_FREE(strm, strm->state->window); 967 968 ZFREE(strm, strm->state); 969 strm->state = Z_NULL; 970 971 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 972} 973 974/* ========================================================================= 975 * Copy the source state to the destination state. 976 * To simplify the source, this is not supported for 16-bit MSDOS (which 977 * doesn't have enough memory anyway to duplicate compression states). 978 */ 979int ZEXPORT deflateCopy (dest, source) 980 z_streamp dest; 981 z_streamp source; 982{ 983#ifdef MAXSEG_64K 984 return Z_STREAM_ERROR; 985#else 986 deflate_state *ds; 987 deflate_state *ss; 988 989 990 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) { 991 return Z_STREAM_ERROR; 992 } 993 994 ss = source->state; 995 996 zmemcpy(dest, source, sizeof(z_stream)); 997 998 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 999 if (ds == Z_NULL) return Z_MEM_ERROR; 1000 dest->state = (struct internal_state FAR *) ds; 1001 zmemcpy(ds, ss, sizeof(deflate_state)); 1002 ds->strm = dest; 1003 1004 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1005 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1006 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1007 ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, 4); 1008 1009 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1010 ds->pending_buf == Z_NULL) { 1011 deflateEnd (dest); 1012 return Z_MEM_ERROR; 1013 } 1014 /* following zmemcpy do not work for 16-bit MSDOS */ 1015 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1016 zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos)); 1017 zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos)); 1018 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); 1019 1020 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1021 ds->sym_buf = ds->pending_buf + ds->lit_bufsize; 1022 1023 ds->l_desc.dyn_tree = ds->dyn_ltree; 1024 ds->d_desc.dyn_tree = ds->dyn_dtree; 1025 ds->bl_desc.dyn_tree = ds->bl_tree; 1026 1027 return Z_OK; 1028#endif /* MAXSEG_64K */ 1029} 1030 1031/* =========================================================================== 1032 * Read a new buffer from the current input stream, update the adler32 1033 * and total number of bytes read. All deflate() input goes through 1034 * this function so some applications may wish to modify it to avoid 1035 * allocating a large strm->next_in buffer and copying from it. 1036 * (See also flush_pending()). 1037 */ 1038local int read_buf(strm, buf, size) 1039 z_streamp strm; 1040 Bytef *buf; 1041 unsigned size; 1042{ 1043 unsigned len = strm->avail_in; 1044 1045 if (len > size) len = size; 1046 if (len == 0) return 0; 1047 1048 strm->avail_in -= len; 1049 1050 if (strm->state->wrap == 1) { 1051 strm->adler = adler32(strm->adler, strm->next_in, len); 1052 } 1053#ifdef GZIP 1054 else if (strm->state->wrap == 2) { 1055 strm->adler = crc32(strm->adler, strm->next_in, len); 1056 } 1057#endif 1058 zmemcpy(buf, strm->next_in, len); 1059 strm->next_in += len; 1060 strm->total_in += len; 1061 1062 return (int)len; 1063} 1064 1065/* =========================================================================== 1066 * Initialize the "longest match" routines for a new zlib stream 1067 */ 1068local void lm_init (s) 1069 deflate_state *s; 1070{ 1071 s->window_size = (ulg)2L*s->w_size; 1072 1073 CLEAR_HASH(s); 1074 1075 /* Set the default configuration parameters: 1076 */ 1077 s->max_lazy_match = configuration_table[s->level].max_lazy; 1078 s->good_match = configuration_table[s->level].good_length; 1079 s->nice_match = configuration_table[s->level].nice_length; 1080 s->max_chain_length = configuration_table[s->level].max_chain; 1081 1082 s->strstart = 0; 1083 s->block_start = 0L; 1084 s->lookahead = 0; 1085 s->match_length = s->prev_length = MIN_MATCH-1; 1086 s->match_available = 0; 1087 s->ins_h = 0; 1088#ifndef FASTEST 1089#ifdef ASMV 1090 match_init(); /* initialize the asm code */ 1091#endif 1092#endif 1093} 1094 1095#ifndef FASTEST 1096/* =========================================================================== 1097 * Set match_start to the longest match starting at the given string and 1098 * return its length. Matches shorter or equal to prev_length are discarded, 1099 * in which case the result is equal to prev_length and match_start is 1100 * garbage. 1101 * IN assertions: cur_match is the head of the hash chain for the current 1102 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1103 * OUT assertion: the match length is not greater than s->lookahead. 1104 */ 1105#ifndef ASMV 1106/* For 80x86 and 680x0, an optimized version will be provided in match.asm or 1107 * match.S. The code will be functionally equivalent. 1108 */ 1109local uInt longest_match(s, cur_match) 1110 deflate_state *s; 1111 IPos cur_match; /* current match */ 1112{ 1113 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1114 register Bytef *scan = s->window + s->strstart; /* current string */ 1115 register Bytef *match; /* matched string */ 1116 register int len; /* length of current match */ 1117 int best_len = s->prev_length; /* best match length so far */ 1118 int nice_match = s->nice_match; /* stop if match long enough */ 1119 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1120 s->strstart - (IPos)MAX_DIST(s) : NIL; 1121 /* Stop when cur_match becomes <= limit. To simplify the code, 1122 * we prevent matches with the string of window index 0. 1123 */ 1124 Posf *prev = s->prev; 1125 uInt wmask = s->w_mask; 1126 1127#ifdef UNALIGNED_OK 1128 /* Compare two bytes at a time. Note: this is not always beneficial. 1129 * Try with and without -DUNALIGNED_OK to check. 1130 */ 1131 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1132 register ush scan_start = *(ushf*)scan; 1133 register ush scan_end = *(ushf*)(scan+best_len-1); 1134#else 1135 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1136 register Byte scan_end1 = scan[best_len-1]; 1137 register Byte scan_end = scan[best_len]; 1138#endif 1139 1140 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1141 * It is easy to get rid of this optimization if necessary. 1142 */ 1143 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1144 1145 /* Do not waste too much time if we already have a good match: */ 1146 if (s->prev_length >= s->good_match) { 1147 chain_length >>= 2; 1148 } 1149 /* Do not look for matches beyond the end of the input. This is necessary 1150 * to make deflate deterministic. 1151 */ 1152 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; 1153 1154 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1155 1156 do { 1157 Assert(cur_match < s->strstart, "no future"); 1158 match = s->window + cur_match; 1159 1160 /* Skip to next match if the match length cannot increase 1161 * or if the match length is less than 2. Note that the checks below 1162 * for insufficient lookahead only occur occasionally for performance 1163 * reasons. Therefore uninitialized memory will be accessed, and 1164 * conditional jumps will be made that depend on those values. 1165 * However the length of the match is limited to the lookahead, so 1166 * the output of deflate is not affected by the uninitialized values. 1167 */ 1168#if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1169 /* This code assumes sizeof(unsigned short) == 2. Do not use 1170 * UNALIGNED_OK if your compiler uses a different size. 1171 */ 1172 if (*(ushf*)(match+best_len-1) != scan_end || 1173 *(ushf*)match != scan_start) continue; 1174 1175 /* It is not necessary to compare scan[2] and match[2] since they are 1176 * always equal when the other bytes match, given that the hash keys 1177 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1178 * strstart+3, +5, ... up to strstart+257. We check for insufficient 1179 * lookahead only every 4th comparison; the 128th check will be made 1180 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is 1181 * necessary to put more guard bytes at the end of the window, or 1182 * to check more often for insufficient lookahead. 1183 */ 1184 Assert(scan[2] == match[2], "scan[2]?"); 1185 scan++, match++; 1186 do { 1187 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1188 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1189 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1190 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1191 scan < strend); 1192 /* The funny "do {}" generates better code on most compilers */ 1193 1194 /* Here, scan <= window+strstart+257 */ 1195 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1196 if (*scan == *match) scan++; 1197 1198 len = (MAX_MATCH - 1) - (int)(strend-scan); 1199 scan = strend - (MAX_MATCH-1); 1200 1201#else /* UNALIGNED_OK */ 1202 1203 if (match[best_len] != scan_end || 1204 match[best_len-1] != scan_end1 || 1205 *match != *scan || 1206 *++match != scan[1]) continue; 1207 1208 /* The check at best_len-1 can be removed because it will be made 1209 * again later. (This heuristic is not always a win.) 1210 * It is not necessary to compare scan[2] and match[2] since they 1211 * are always equal when the other bytes match, given that 1212 * the hash keys are equal and that HASH_BITS >= 8. 1213 */ 1214 scan += 2, match++; 1215 Assert(*scan == *match, "match[2]?"); 1216 1217 /* We check for insufficient lookahead only every 8th comparison; 1218 * the 256th check will be made at strstart+258. 1219 */ 1220 do { 1221 } while (*++scan == *++match && *++scan == *++match && 1222 *++scan == *++match && *++scan == *++match && 1223 *++scan == *++match && *++scan == *++match && 1224 *++scan == *++match && *++scan == *++match && 1225 scan < strend); 1226 1227 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1228 1229 len = MAX_MATCH - (int)(strend - scan); 1230 scan = strend - MAX_MATCH; 1231 1232#endif /* UNALIGNED_OK */ 1233 1234 if (len > best_len) { 1235 s->match_start = cur_match; 1236 best_len = len; 1237 if (len >= nice_match) break; 1238#ifdef UNALIGNED_OK 1239 scan_end = *(ushf*)(scan+best_len-1); 1240#else 1241 scan_end1 = scan[best_len-1]; 1242 scan_end = scan[best_len]; 1243#endif 1244 } 1245 } while ((cur_match = prev[cur_match & wmask]) > limit 1246 && --chain_length != 0); 1247 1248 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1249 return s->lookahead; 1250} 1251#endif /* ASMV */ 1252 1253#else /* FASTEST */ 1254 1255/* --------------------------------------------------------------------------- 1256 * Optimized version for FASTEST only 1257 */ 1258local uInt longest_match(s, cur_match) 1259 deflate_state *s; 1260 IPos cur_match; /* current match */ 1261{ 1262 register Bytef *scan = s->window + s->strstart; /* current string */ 1263 register Bytef *match; /* matched string */ 1264 register int len; /* length of current match */ 1265 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1266 1267 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1268 * It is easy to get rid of this optimization if necessary. 1269 */ 1270 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1271 1272 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1273 1274 Assert(cur_match < s->strstart, "no future"); 1275 1276 match = s->window + cur_match; 1277 1278 /* Return failure if the match length is less than 2: 1279 */ 1280 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1281 1282 /* The check at best_len-1 can be removed because it will be made 1283 * again later. (This heuristic is not always a win.) 1284 * It is not necessary to compare scan[2] and match[2] since they 1285 * are always equal when the other bytes match, given that 1286 * the hash keys are equal and that HASH_BITS >= 8. 1287 */ 1288 scan += 2, match += 2; 1289 Assert(*scan == *match, "match[2]?"); 1290 1291 /* We check for insufficient lookahead only every 8th comparison; 1292 * the 256th check will be made at strstart+258. 1293 */ 1294 do { 1295 } while (*++scan == *++match && *++scan == *++match && 1296 *++scan == *++match && *++scan == *++match && 1297 *++scan == *++match && *++scan == *++match && 1298 *++scan == *++match && *++scan == *++match && 1299 scan < strend); 1300 1301 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1302 1303 len = MAX_MATCH - (int)(strend - scan); 1304 1305 if (len < MIN_MATCH) return MIN_MATCH - 1; 1306 1307 s->match_start = cur_match; 1308 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1309} 1310 1311#endif /* FASTEST */ 1312 1313#ifdef DEBUG 1314/* =========================================================================== 1315 * Check that the match at match_start is indeed a match. 1316 */ 1317local void check_match(s, start, match, length) 1318 deflate_state *s; 1319 IPos start, match; 1320 int length; 1321{ 1322 /* check that the match is indeed a match */ 1323 if (zmemcmp(s->window + match, 1324 s->window + start, length) != EQUAL) { 1325 fprintf(stderr, " start %u, match %u, length %d\n", 1326 start, match, length); 1327 do { 1328 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); 1329 } while (--length != 0); 1330 z_error("invalid match"); 1331 } 1332 if (z_verbose > 1) { 1333 fprintf(stderr,"\\[%d,%d]", start-match, length); 1334 do { putc(s->window[start++], stderr); } while (--length != 0); 1335 } 1336} 1337#else 1338# define check_match(s, start, match, length) 1339#endif /* DEBUG */ 1340 1341/* =========================================================================== 1342 * Fill the window when the lookahead becomes insufficient. 1343 * Updates strstart and lookahead. 1344 * 1345 * IN assertion: lookahead < MIN_LOOKAHEAD 1346 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 1347 * At least one byte has been read, or avail_in == 0; reads are 1348 * performed for at least two bytes (required for the zip translate_eol 1349 * option -- not supported here). 1350 */ 1351local void fill_window(s) 1352 deflate_state *s; 1353{ 1354 register unsigned n, m; 1355 register Posf *p; 1356 unsigned more; /* Amount of free space at the end of the window. */ 1357 uInt wsize = s->w_size; 1358 1359 do { 1360 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 1361 1362 /* Deal with !@#$% 64K limit: */ 1363 if (sizeof(int) <= 2) { 1364 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 1365 more = wsize; 1366 1367 } else if (more == (unsigned)(-1)) { 1368 /* Very unlikely, but possible on 16 bit machine if 1369 * strstart == 0 && lookahead == 1 (input done a byte at time) 1370 */ 1371 more--; 1372 } 1373 } 1374 1375 /* If the window is almost full and there is insufficient lookahead, 1376 * move the upper half to the lower one to make room in the upper half. 1377 */ 1378 if (s->strstart >= wsize+MAX_DIST(s)) { 1379 1380 zmemcpy(s->window, s->window+wsize, (unsigned)wsize); 1381 s->match_start -= wsize; 1382 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 1383 s->block_start -= (long) wsize; 1384 1385 /* Slide the hash table (could be avoided with 32 bit values 1386 at the expense of memory usage). We slide even when level == 0 1387 to keep the hash table consistent if we switch back to level > 0 1388 later. (Using level 0 permanently is not an optimal usage of 1389 zlib, so we don't care about this pathological case.) 1390 */ 1391 n = s->hash_size; 1392 p = &s->head[n]; 1393 do { 1394 m = *--p; 1395 *p = (Pos)(m >= wsize ? m-wsize : NIL); 1396 } while (--n); 1397 1398 n = wsize; 1399#ifndef FASTEST 1400 p = &s->prev[n]; 1401 do { 1402 m = *--p; 1403 *p = (Pos)(m >= wsize ? m-wsize : NIL); 1404 /* If n is not on any hash chain, prev[n] is garbage but 1405 * its value will never be used. 1406 */ 1407 } while (--n); 1408#endif 1409 more += wsize; 1410 } 1411 if (s->strm->avail_in == 0) return; 1412 1413 /* If there was no sliding: 1414 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 1415 * more == window_size - lookahead - strstart 1416 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 1417 * => more >= window_size - 2*WSIZE + 2 1418 * In the BIG_MEM or MMAP case (not yet supported), 1419 * window_size == input_size + MIN_LOOKAHEAD && 1420 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 1421 * Otherwise, window_size == 2*WSIZE so more >= 2. 1422 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 1423 */ 1424 Assert(more >= 2, "more < 2"); 1425 1426 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 1427 s->lookahead += n; 1428 1429 /* Initialize the hash value now that we have some input: */ 1430 if (s->lookahead >= MIN_MATCH) { 1431 s->ins_h = s->window[s->strstart]; 1432 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); 1433#if MIN_MATCH != 3 1434 Call UPDATE_HASH() MIN_MATCH-3 more times 1435#endif 1436 } 1437 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 1438 * but this is not important since only literal bytes will be emitted. 1439 */ 1440 1441 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 1442 1443 /* If the WIN_INIT bytes after the end of the current data have never been 1444 * written, then zero those bytes in order to avoid memory check reports of 1445 * the use of uninitialized (or uninitialised as Julian writes) bytes by 1446 * the longest match routines. Update the high water mark for the next 1447 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 1448 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 1449 */ 1450 if (s->high_water < s->window_size) { 1451 ulg curr = s->strstart + (ulg)(s->lookahead); 1452 ulg init; 1453 1454 if (s->high_water < curr) { 1455 /* Previous high water mark below current data -- zero WIN_INIT 1456 * bytes or up to end of window, whichever is less. 1457 */ 1458 init = s->window_size - curr; 1459 if (init > WIN_INIT) 1460 init = WIN_INIT; 1461 zmemzero(s->window + curr, (unsigned)init); 1462 s->high_water = curr + init; 1463 } 1464 else if (s->high_water < (ulg)curr + WIN_INIT) { 1465 /* High water mark at or above current data, but below current data 1466 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 1467 * to end of window, whichever is less. 1468 */ 1469 init = (ulg)curr + WIN_INIT - s->high_water; 1470 if (init > s->window_size - s->high_water) 1471 init = s->window_size - s->high_water; 1472 zmemzero(s->window + s->high_water, (unsigned)init); 1473 s->high_water += init; 1474 } 1475 } 1476} 1477 1478/* =========================================================================== 1479 * Flush the current block, with given end-of-file flag. 1480 * IN assertion: strstart is set to the end of the current match. 1481 */ 1482#define FLUSH_BLOCK_ONLY(s, last) { \ 1483 _tr_flush_block(s, (s->block_start >= 0L ? \ 1484 (charf *)&s->window[(unsigned)s->block_start] : \ 1485 (charf *)Z_NULL), \ 1486 (ulg)((long)s->strstart - s->block_start), \ 1487 (last)); \ 1488 s->block_start = s->strstart; \ 1489 flush_pending(s->strm); \ 1490 Tracev((stderr,"[FLUSH]")); \ 1491} 1492 1493/* Same but force premature exit if necessary. */ 1494#define FLUSH_BLOCK(s, last) { \ 1495 FLUSH_BLOCK_ONLY(s, last); \ 1496 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1497} 1498 1499/* =========================================================================== 1500 * Copy without compression as much as possible from the input stream, return 1501 * the current block state. 1502 * This function does not insert new strings in the dictionary since 1503 * uncompressible data is probably not useful. This function is used 1504 * only for the level=0 compression option. 1505 * NOTE: this function should be optimized to avoid extra copying from 1506 * window to pending_buf. 1507 */ 1508local block_state deflate_stored(s, flush) 1509 deflate_state *s; 1510 int flush; 1511{ 1512 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited 1513 * to pending_buf_size, and each stored block has a 5 byte header: 1514 */ 1515 ulg max_block_size = 0xffff; 1516 ulg max_start; 1517 1518 if (max_block_size > s->pending_buf_size - 5) { 1519 max_block_size = s->pending_buf_size - 5; 1520 } 1521 1522 /* Copy as much as possible from input to output: */ 1523 for (;;) { 1524 /* Fill the window as much as possible: */ 1525 if (s->lookahead <= 1) { 1526 1527 Assert(s->strstart < s->w_size+MAX_DIST(s) || 1528 s->block_start >= (long)s->w_size, "slide too late"); 1529 1530 fill_window(s); 1531 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more; 1532 1533 if (s->lookahead == 0) break; /* flush the current block */ 1534 } 1535 Assert(s->block_start >= 0L, "block gone"); 1536 1537 s->strstart += s->lookahead; 1538 s->lookahead = 0; 1539 1540 /* Emit a stored block if pending_buf will be full: */ 1541 max_start = s->block_start + max_block_size; 1542 if (s->strstart == 0 || (ulg)s->strstart >= max_start) { 1543 /* strstart == 0 is possible when wraparound on 16-bit machine */ 1544 s->lookahead = (uInt)(s->strstart - max_start); 1545 s->strstart = (uInt)max_start; 1546 FLUSH_BLOCK(s, 0); 1547 } 1548 /* Flush if we may have to slide, otherwise block_start may become 1549 * negative and the data will be gone: 1550 */ 1551 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) { 1552 FLUSH_BLOCK(s, 0); 1553 } 1554 } 1555 FLUSH_BLOCK(s, flush == Z_FINISH); 1556 return flush == Z_FINISH ? finish_done : block_done; 1557} 1558 1559/* =========================================================================== 1560 * Compress as much as possible from the input stream, return the current 1561 * block state. 1562 * This function does not perform lazy evaluation of matches and inserts 1563 * new strings in the dictionary only for unmatched strings or for short 1564 * matches. It is used only for the fast compression options. 1565 */ 1566local block_state deflate_fast(s, flush) 1567 deflate_state *s; 1568 int flush; 1569{ 1570 IPos hash_head; /* head of the hash chain */ 1571 int bflush; /* set if current block must be flushed */ 1572 1573 for (;;) { 1574 /* Make sure that we always have enough lookahead, except 1575 * at the end of the input file. We need MAX_MATCH bytes 1576 * for the next match, plus MIN_MATCH bytes to insert the 1577 * string following the next match. 1578 */ 1579 if (s->lookahead < MIN_LOOKAHEAD) { 1580 fill_window(s); 1581 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1582 return need_more; 1583 } 1584 if (s->lookahead == 0) break; /* flush the current block */ 1585 } 1586 1587 /* Insert the string window[strstart .. strstart+2] in the 1588 * dictionary, and set hash_head to the head of the hash chain: 1589 */ 1590 hash_head = NIL; 1591 if (s->lookahead >= MIN_MATCH) { 1592 INSERT_STRING(s, s->strstart, hash_head); 1593 } 1594 1595 /* Find the longest match, discarding those <= prev_length. 1596 * At this point we have always match_length < MIN_MATCH 1597 */ 1598 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1599 /* To simplify the code, we prevent matches with the string 1600 * of window index 0 (in particular we have to avoid a match 1601 * of the string with itself at the start of the input file). 1602 */ 1603 s->match_length = longest_match (s, hash_head); 1604 /* longest_match() sets match_start */ 1605 } 1606 if (s->match_length >= MIN_MATCH) { 1607 check_match(s, s->strstart, s->match_start, s->match_length); 1608 1609 _tr_tally_dist(s, s->strstart - s->match_start, 1610 s->match_length - MIN_MATCH, bflush); 1611 1612 s->lookahead -= s->match_length; 1613 1614 /* Insert new strings in the hash table only if the match length 1615 * is not too large. This saves time but degrades compression. 1616 */ 1617#ifndef FASTEST 1618 if (s->match_length <= s->max_insert_length && 1619 s->lookahead >= MIN_MATCH) { 1620 s->match_length--; /* string at strstart already in table */ 1621 do { 1622 s->strstart++; 1623 INSERT_STRING(s, s->strstart, hash_head); 1624 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1625 * always MIN_MATCH bytes ahead. 1626 */ 1627 } while (--s->match_length != 0); 1628 s->strstart++; 1629 } else 1630#endif 1631 { 1632 s->strstart += s->match_length; 1633 s->match_length = 0; 1634 s->ins_h = s->window[s->strstart]; 1635 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); 1636#if MIN_MATCH != 3 1637 Call UPDATE_HASH() MIN_MATCH-3 more times 1638#endif 1639 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1640 * matter since it will be recomputed at next deflate call. 1641 */ 1642 } 1643 } else { 1644 /* No match, output a literal byte */ 1645 Tracevv((stderr,"%c", s->window[s->strstart])); 1646 _tr_tally_lit (s, s->window[s->strstart], bflush); 1647 s->lookahead--; 1648 s->strstart++; 1649 } 1650 if (bflush) FLUSH_BLOCK(s, 0); 1651 } 1652 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1653 if (flush == Z_FINISH) { 1654 FLUSH_BLOCK(s, 1); 1655 return finish_done; 1656 } 1657 if (s->sym_next) 1658 FLUSH_BLOCK(s, 0); 1659 return block_done; 1660} 1661 1662#ifndef FASTEST 1663/* =========================================================================== 1664 * Same as above, but achieves better compression. We use a lazy 1665 * evaluation for matches: a match is finally adopted only if there is 1666 * no better match at the next window position. 1667 */ 1668local block_state deflate_slow(s, flush) 1669 deflate_state *s; 1670 int flush; 1671{ 1672 IPos hash_head; /* head of hash chain */ 1673 int bflush; /* set if current block must be flushed */ 1674 1675 /* Process the input block. */ 1676 for (;;) { 1677 /* Make sure that we always have enough lookahead, except 1678 * at the end of the input file. We need MAX_MATCH bytes 1679 * for the next match, plus MIN_MATCH bytes to insert the 1680 * string following the next match. 1681 */ 1682 if (s->lookahead < MIN_LOOKAHEAD) { 1683 fill_window(s); 1684 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1685 return need_more; 1686 } 1687 if (s->lookahead == 0) break; /* flush the current block */ 1688 } 1689 1690 /* Insert the string window[strstart .. strstart+2] in the 1691 * dictionary, and set hash_head to the head of the hash chain: 1692 */ 1693 hash_head = NIL; 1694 if (s->lookahead >= MIN_MATCH) { 1695 INSERT_STRING(s, s->strstart, hash_head); 1696 } 1697 1698 /* Find the longest match, discarding those <= prev_length. 1699 */ 1700 s->prev_length = s->match_length, s->prev_match = s->match_start; 1701 s->match_length = MIN_MATCH-1; 1702 1703 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1704 s->strstart - hash_head <= MAX_DIST(s)) { 1705 /* To simplify the code, we prevent matches with the string 1706 * of window index 0 (in particular we have to avoid a match 1707 * of the string with itself at the start of the input file). 1708 */ 1709 s->match_length = longest_match (s, hash_head); 1710 /* longest_match() sets match_start */ 1711 1712 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1713#if TOO_FAR <= 32767 1714 || (s->match_length == MIN_MATCH && 1715 s->strstart - s->match_start > TOO_FAR) 1716#endif 1717 )) { 1718 1719 /* If prev_match is also MIN_MATCH, match_start is garbage 1720 * but we will ignore the current match anyway. 1721 */ 1722 s->match_length = MIN_MATCH-1; 1723 } 1724 } 1725 /* If there was a match at the previous step and the current 1726 * match is not better, output the previous match: 1727 */ 1728 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1729 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1730 /* Do not insert strings in hash table beyond this. */ 1731 1732 check_match(s, s->strstart-1, s->prev_match, s->prev_length); 1733 1734 _tr_tally_dist(s, s->strstart -1 - s->prev_match, 1735 s->prev_length - MIN_MATCH, bflush); 1736 1737 /* Insert in hash table all strings up to the end of the match. 1738 * strstart-1 and strstart are already inserted. If there is not 1739 * enough lookahead, the last two strings are not inserted in 1740 * the hash table. 1741 */ 1742 s->lookahead -= s->prev_length-1; 1743 s->prev_length -= 2; 1744 do { 1745 if (++s->strstart <= max_insert) { 1746 INSERT_STRING(s, s->strstart, hash_head); 1747 } 1748 } while (--s->prev_length != 0); 1749 s->match_available = 0; 1750 s->match_length = MIN_MATCH-1; 1751 s->strstart++; 1752 1753 if (bflush) FLUSH_BLOCK(s, 0); 1754 1755 } else if (s->match_available) { 1756 /* If there was no match at the previous position, output a 1757 * single literal. If there was a match but the current match 1758 * is longer, truncate the previous match to a single literal. 1759 */ 1760 Tracevv((stderr,"%c", s->window[s->strstart-1])); 1761 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 1762 if (bflush) { 1763 FLUSH_BLOCK_ONLY(s, 0); 1764 } 1765 s->strstart++; 1766 s->lookahead--; 1767 if (s->strm->avail_out == 0) return need_more; 1768 } else { 1769 /* There is no previous match to compare with, wait for 1770 * the next step to decide. 1771 */ 1772 s->match_available = 1; 1773 s->strstart++; 1774 s->lookahead--; 1775 } 1776 } 1777 Assert (flush != Z_NO_FLUSH, "no flush?"); 1778 if (s->match_available) { 1779 Tracevv((stderr,"%c", s->window[s->strstart-1])); 1780 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 1781 s->match_available = 0; 1782 } 1783 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1784 if (flush == Z_FINISH) { 1785 FLUSH_BLOCK(s, 1); 1786 return finish_done; 1787 } 1788 if (s->sym_next) 1789 FLUSH_BLOCK(s, 0); 1790 return block_done; 1791} 1792#endif /* FASTEST */ 1793 1794/* =========================================================================== 1795 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 1796 * one. Do not maintain a hash table. (It will be regenerated if this run of 1797 * deflate switches away from Z_RLE.) 1798 */ 1799local block_state deflate_rle(s, flush) 1800 deflate_state *s; 1801 int flush; 1802{ 1803 int bflush; /* set if current block must be flushed */ 1804 uInt prev; /* byte at distance one to match */ 1805 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 1806 1807 for (;;) { 1808 /* Make sure that we always have enough lookahead, except 1809 * at the end of the input file. We need MAX_MATCH bytes 1810 * for the longest encodable run. 1811 */ 1812 if (s->lookahead < MAX_MATCH) { 1813 fill_window(s); 1814 if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) { 1815 return need_more; 1816 } 1817 if (s->lookahead == 0) break; /* flush the current block */ 1818 } 1819 1820 /* See how many times the previous byte repeats */ 1821 s->match_length = 0; 1822 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 1823 scan = s->window + s->strstart - 1; 1824 prev = *scan; 1825 if (prev == *++scan && prev == *++scan && prev == *++scan) { 1826 strend = s->window + s->strstart + MAX_MATCH; 1827 do { 1828 } while (prev == *++scan && prev == *++scan && 1829 prev == *++scan && prev == *++scan && 1830 prev == *++scan && prev == *++scan && 1831 prev == *++scan && prev == *++scan && 1832 scan < strend); 1833 s->match_length = MAX_MATCH - (int)(strend - scan); 1834 if (s->match_length > s->lookahead) 1835 s->match_length = s->lookahead; 1836 } 1837 } 1838 1839 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 1840 if (s->match_length >= MIN_MATCH) { 1841 check_match(s, s->strstart, s->strstart - 1, s->match_length); 1842 1843 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 1844 1845 s->lookahead -= s->match_length; 1846 s->strstart += s->match_length; 1847 s->match_length = 0; 1848 } else { 1849 /* No match, output a literal byte */ 1850 Tracevv((stderr,"%c", s->window[s->strstart])); 1851 _tr_tally_lit (s, s->window[s->strstart], bflush); 1852 s->lookahead--; 1853 s->strstart++; 1854 } 1855 if (bflush) FLUSH_BLOCK(s, 0); 1856 } 1857 s->insert = 0; 1858 if (flush == Z_FINISH) { 1859 FLUSH_BLOCK(s, 1); 1860 return finish_done; 1861 } 1862 if (s->sym_next) 1863 FLUSH_BLOCK(s, 0); 1864 return block_done; 1865} 1866 1867/* =========================================================================== 1868 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 1869 * (It will be regenerated if this run of deflate switches away from Huffman.) 1870 */ 1871local block_state deflate_huff(s, flush) 1872 deflate_state *s; 1873 int flush; 1874{ 1875 int bflush; /* set if current block must be flushed */ 1876 1877 for (;;) { 1878 /* Make sure that we have a literal to write. */ 1879 if (s->lookahead == 0) { 1880 fill_window(s); 1881 if (s->lookahead == 0) { 1882 if (flush == Z_NO_FLUSH) 1883 return need_more; 1884 break; /* flush the current block */ 1885 } 1886 } 1887 1888 /* Output a literal byte */ 1889 s->match_length = 0; 1890 Tracevv((stderr,"%c", s->window[s->strstart])); 1891 _tr_tally_lit (s, s->window[s->strstart], bflush); 1892 s->lookahead--; 1893 s->strstart++; 1894 if (bflush) FLUSH_BLOCK(s, 0); 1895 } 1896 s->insert = 0; 1897 if (flush == Z_FINISH) { 1898 FLUSH_BLOCK(s, 1); 1899 return finish_done; 1900 } 1901 if (s->sym_next) 1902 FLUSH_BLOCK(s, 0); 1903 return block_done; 1904} 1905