1 /* deflate.c -- compress data using the deflation algorithm 2 * Copyright (C) 1995-2023 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 1.3 Copyright 1995-2023 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 typedef enum { 64 need_more, /* block not completed, need more input or more output */ 65 block_done, /* block flush performed */ 66 finish_started, /* finish started, need only more output at next deflate */ 67 finish_done /* finish done, accept no more input or output */ 68 } block_state; 69 70 typedef block_state (*compress_func)(deflate_state *s, int flush); 71 /* Compression function. Returns the block state after the call. */ 72 73 local block_state deflate_stored(deflate_state *s, int flush); 74 local block_state deflate_fast(deflate_state *s, int flush); 75 #ifndef FASTEST 76 local block_state deflate_slow(deflate_state *s, int flush); 77 #endif 78 local block_state deflate_rle(deflate_state *s, int flush); 79 local block_state deflate_huff(deflate_state *s, int flush); 80 81 /* =========================================================================== 82 * Local data 83 */ 84 85 #define NIL 0 86 /* Tail of hash chains */ 87 88 #ifndef TOO_FAR 89 # define TOO_FAR 4096 90 #endif 91 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ 92 93 /* Values for max_lazy_match, good_match and max_chain_length, depending on 94 * the desired pack level (0..9). The values given below have been tuned to 95 * exclude worst case performance for pathological files. Better values may be 96 * found for specific files. 97 */ 98 typedef struct config_s { 99 ush good_length; /* reduce lazy search above this match length */ 100 ush max_lazy; /* do not perform lazy search above this match length */ 101 ush nice_length; /* quit search above this match length */ 102 ush max_chain; 103 compress_func func; 104 } config; 105 106 #ifdef FASTEST 107 local const config configuration_table[2] = { 108 /* good lazy nice chain */ 109 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 110 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ 111 #else 112 local const config configuration_table[10] = { 113 /* good lazy nice chain */ 114 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 115 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ 116 /* 2 */ {4, 5, 16, 8, deflate_fast}, 117 /* 3 */ {4, 6, 32, 32, deflate_fast}, 118 119 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ 120 /* 5 */ {8, 16, 32, 32, deflate_slow}, 121 /* 6 */ {8, 16, 128, 128, deflate_slow}, 122 /* 7 */ {8, 32, 128, 256, deflate_slow}, 123 /* 8 */ {32, 128, 258, 1024, deflate_slow}, 124 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ 125 #endif 126 127 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 128 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different 129 * meaning. 130 */ 131 132 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */ 133 #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0)) 134 135 /* =========================================================================== 136 * Update a hash value with the given input byte 137 * IN assertion: all calls to UPDATE_HASH are made with consecutive input 138 * characters, so that a running hash key can be computed from the previous 139 * key instead of complete recalculation each time. 140 */ 141 #define UPDATE_HASH(s,h,c) (h = (((h) << s->hash_shift) ^ (c)) & s->hash_mask) 142 143 144 /* =========================================================================== 145 * Insert string str in the dictionary and set match_head to the previous head 146 * of the hash chain (the most recent string with same hash key). Return 147 * the previous length of the hash chain. 148 * If this file is compiled with -DFASTEST, the compression level is forced 149 * to 1, and no hash chains are maintained. 150 * IN assertion: all calls to INSERT_STRING are made with consecutive input 151 * characters and the first MIN_MATCH bytes of str are valid (except for 152 * the last MIN_MATCH-1 bytes of the input file). 153 */ 154 #ifdef FASTEST 155 #define INSERT_STRING(s, str, match_head) \ 156 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 157 match_head = s->head[s->ins_h], \ 158 s->head[s->ins_h] = (Pos)(str)) 159 #else 160 #define INSERT_STRING(s, str, match_head) \ 161 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 162 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ 163 s->head[s->ins_h] = (Pos)(str)) 164 #endif 165 166 /* =========================================================================== 167 * Initialize the hash table (avoiding 64K overflow for 16 bit systems). 168 * prev[] will be initialized on the fly. 169 */ 170 #define CLEAR_HASH(s) \ 171 do { \ 172 s->head[s->hash_size - 1] = NIL; \ 173 zmemzero((Bytef *)s->head, \ 174 (unsigned)(s->hash_size - 1)*sizeof(*s->head)); \ 175 } while (0) 176 177 /* =========================================================================== 178 * Slide the hash table when sliding the window down (could be avoided with 32 179 * bit values at the expense of memory usage). We slide even when level == 0 to 180 * keep the hash table consistent if we switch back to level > 0 later. 181 */ 182 #if defined(__has_feature) 183 # if __has_feature(memory_sanitizer) 184 __attribute__((no_sanitize("memory"))) 185 # endif 186 #endif 187 local void slide_hash(deflate_state *s) { 188 unsigned n, m; 189 Posf *p; 190 uInt wsize = s->w_size; 191 192 n = s->hash_size; 193 p = &s->head[n]; 194 do { 195 m = *--p; 196 *p = (Pos)(m >= wsize ? m - wsize : NIL); 197 } while (--n); 198 n = wsize; 199 #ifndef FASTEST 200 p = &s->prev[n]; 201 do { 202 m = *--p; 203 *p = (Pos)(m >= wsize ? m - wsize : NIL); 204 /* If n is not on any hash chain, prev[n] is garbage but 205 * its value will never be used. 206 */ 207 } while (--n); 208 #endif 209 } 210 211 /* =========================================================================== 212 * Read a new buffer from the current input stream, update the adler32 213 * and total number of bytes read. All deflate() input goes through 214 * this function so some applications may wish to modify it to avoid 215 * allocating a large strm->next_in buffer and copying from it. 216 * (See also flush_pending()). 217 */ 218 local unsigned read_buf(z_streamp strm, Bytef *buf, unsigned size) { 219 unsigned len = strm->avail_in; 220 221 if (len > size) len = size; 222 if (len == 0) return 0; 223 224 strm->avail_in -= len; 225 226 zmemcpy(buf, strm->next_in, len); 227 if (strm->state->wrap == 1) { 228 strm->adler = adler32(strm->adler, buf, len); 229 } 230 #ifdef GZIP 231 else if (strm->state->wrap == 2) { 232 strm->adler = crc32(strm->adler, buf, len); 233 } 234 #endif 235 strm->next_in += len; 236 strm->total_in += len; 237 238 return len; 239 } 240 241 /* =========================================================================== 242 * Fill the window when the lookahead becomes insufficient. 243 * Updates strstart and lookahead. 244 * 245 * IN assertion: lookahead < MIN_LOOKAHEAD 246 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 247 * At least one byte has been read, or avail_in == 0; reads are 248 * performed for at least two bytes (required for the zip translate_eol 249 * option -- not supported here). 250 */ 251 local void fill_window(deflate_state *s) { 252 unsigned n; 253 unsigned more; /* Amount of free space at the end of the window. */ 254 uInt wsize = s->w_size; 255 256 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); 257 258 do { 259 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 260 261 /* Deal with !@#$% 64K limit: */ 262 if (sizeof(int) <= 2) { 263 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 264 more = wsize; 265 266 } else if (more == (unsigned)(-1)) { 267 /* Very unlikely, but possible on 16 bit machine if 268 * strstart == 0 && lookahead == 1 (input done a byte at time) 269 */ 270 more--; 271 } 272 } 273 274 /* If the window is almost full and there is insufficient lookahead, 275 * move the upper half to the lower one to make room in the upper half. 276 */ 277 if (s->strstart >= wsize + MAX_DIST(s)) { 278 279 zmemcpy(s->window, s->window + wsize, (unsigned)wsize - more); 280 s->match_start -= wsize; 281 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 282 s->block_start -= (long) wsize; 283 if (s->insert > s->strstart) 284 s->insert = s->strstart; 285 slide_hash(s); 286 more += wsize; 287 } 288 if (s->strm->avail_in == 0) break; 289 290 /* If there was no sliding: 291 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 292 * more == window_size - lookahead - strstart 293 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 294 * => more >= window_size - 2*WSIZE + 2 295 * In the BIG_MEM or MMAP case (not yet supported), 296 * window_size == input_size + MIN_LOOKAHEAD && 297 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 298 * Otherwise, window_size == 2*WSIZE so more >= 2. 299 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 300 */ 301 Assert(more >= 2, "more < 2"); 302 303 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 304 s->lookahead += n; 305 306 /* Initialize the hash value now that we have some input: */ 307 if (s->lookahead + s->insert >= MIN_MATCH) { 308 uInt str = s->strstart - s->insert; 309 s->ins_h = s->window[str]; 310 UPDATE_HASH(s, s->ins_h, s->window[str + 1]); 311 #if MIN_MATCH != 3 312 Call UPDATE_HASH() MIN_MATCH-3 more times 313 #endif 314 while (s->insert) { 315 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 316 #ifndef FASTEST 317 s->prev[str & s->w_mask] = s->head[s->ins_h]; 318 #endif 319 s->head[s->ins_h] = (Pos)str; 320 str++; 321 s->insert--; 322 if (s->lookahead + s->insert < MIN_MATCH) 323 break; 324 } 325 } 326 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 327 * but this is not important since only literal bytes will be emitted. 328 */ 329 330 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 331 332 /* If the WIN_INIT bytes after the end of the current data have never been 333 * written, then zero those bytes in order to avoid memory check reports of 334 * the use of uninitialized (or uninitialised as Julian writes) bytes by 335 * the longest match routines. Update the high water mark for the next 336 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 337 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 338 */ 339 if (s->high_water < s->window_size) { 340 ulg curr = s->strstart + (ulg)(s->lookahead); 341 ulg init; 342 343 if (s->high_water < curr) { 344 /* Previous high water mark below current data -- zero WIN_INIT 345 * bytes or up to end of window, whichever is less. 346 */ 347 init = s->window_size - curr; 348 if (init > WIN_INIT) 349 init = WIN_INIT; 350 zmemzero(s->window + curr, (unsigned)init); 351 s->high_water = curr + init; 352 } 353 else if (s->high_water < (ulg)curr + WIN_INIT) { 354 /* High water mark at or above current data, but below current data 355 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 356 * to end of window, whichever is less. 357 */ 358 init = (ulg)curr + WIN_INIT - s->high_water; 359 if (init > s->window_size - s->high_water) 360 init = s->window_size - s->high_water; 361 zmemzero(s->window + s->high_water, (unsigned)init); 362 s->high_water += init; 363 } 364 } 365 366 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 367 "not enough room for search"); 368 } 369 370 /* ========================================================================= */ 371 int ZEXPORT deflateInit_(z_streamp strm, int level, const char *version, 372 int stream_size) { 373 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, 374 Z_DEFAULT_STRATEGY, version, stream_size); 375 /* To do: ignore strm->next_in if we use it as window */ 376 } 377 378 /* ========================================================================= */ 379 int ZEXPORT deflateInit2_(z_streamp strm, int level, int method, 380 int windowBits, int memLevel, int strategy, 381 const char *version, int stream_size) { 382 deflate_state *s; 383 int wrap = 1; 384 static const char my_version[] = ZLIB_VERSION; 385 386 if (version == Z_NULL || version[0] != my_version[0] || 387 stream_size != sizeof(z_stream)) { 388 return Z_VERSION_ERROR; 389 } 390 if (strm == Z_NULL) return Z_STREAM_ERROR; 391 392 strm->msg = Z_NULL; 393 if (strm->zalloc == (alloc_func)0) { 394 #if defined(Z_SOLO) && !defined(_KERNEL) 395 return Z_STREAM_ERROR; 396 #else 397 strm->zalloc = zcalloc; 398 strm->opaque = (voidpf)0; 399 #endif 400 } 401 if (strm->zfree == (free_func)0) 402 #if defined(Z_SOLO) && !defined(_KERNEL) 403 return Z_STREAM_ERROR; 404 #else 405 strm->zfree = zcfree; 406 #endif 407 408 #ifdef FASTEST 409 if (level != 0) level = 1; 410 #else 411 if (level == Z_DEFAULT_COMPRESSION) level = 6; 412 #endif 413 414 if (windowBits < 0) { /* suppress zlib wrapper */ 415 wrap = 0; 416 if (windowBits < -15) 417 return Z_STREAM_ERROR; 418 windowBits = -windowBits; 419 } 420 #ifdef GZIP 421 else if (windowBits > 15) { 422 wrap = 2; /* write gzip wrapper instead */ 423 windowBits -= 16; 424 } 425 #endif 426 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 427 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 428 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) { 429 return Z_STREAM_ERROR; 430 } 431 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 432 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 433 if (s == Z_NULL) return Z_MEM_ERROR; 434 strm->state = (struct internal_state FAR *)s; 435 s->strm = strm; 436 s->status = INIT_STATE; /* to pass state test in deflateReset() */ 437 438 s->wrap = wrap; 439 s->gzhead = Z_NULL; 440 s->w_bits = (uInt)windowBits; 441 s->w_size = 1 << s->w_bits; 442 s->w_mask = s->w_size - 1; 443 444 s->hash_bits = (uInt)memLevel + 7; 445 s->hash_size = 1 << s->hash_bits; 446 s->hash_mask = s->hash_size - 1; 447 s->hash_shift = ((s->hash_bits + MIN_MATCH-1) / MIN_MATCH); 448 449 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 450 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 451 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 452 453 s->high_water = 0; /* nothing written to s->window yet */ 454 455 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 456 457 /* We overlay pending_buf and sym_buf. This works since the average size 458 * for length/distance pairs over any compressed block is assured to be 31 459 * bits or less. 460 * 461 * Analysis: The longest fixed codes are a length code of 8 bits plus 5 462 * extra bits, for lengths 131 to 257. The longest fixed distance codes are 463 * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest 464 * possible fixed-codes length/distance pair is then 31 bits total. 465 * 466 * sym_buf starts one-fourth of the way into pending_buf. So there are 467 * three bytes in sym_buf for every four bytes in pending_buf. Each symbol 468 * in sym_buf is three bytes -- two for the distance and one for the 469 * literal/length. As each symbol is consumed, the pointer to the next 470 * sym_buf value to read moves forward three bytes. From that symbol, up to 471 * 31 bits are written to pending_buf. The closest the written pending_buf 472 * bits gets to the next sym_buf symbol to read is just before the last 473 * code is written. At that time, 31*(n - 2) bits have been written, just 474 * after 24*(n - 2) bits have been consumed from sym_buf. sym_buf starts at 475 * 8*n bits into pending_buf. (Note that the symbol buffer fills when n - 1 476 * symbols are written.) The closest the writing gets to what is unread is 477 * then n + 14 bits. Here n is lit_bufsize, which is 16384 by default, and 478 * can range from 128 to 32768. 479 * 480 * Therefore, at a minimum, there are 142 bits of space between what is 481 * written and what is read in the overlain buffers, so the symbols cannot 482 * be overwritten by the compressed data. That space is actually 139 bits, 483 * due to the three-bit fixed-code block header. 484 * 485 * That covers the case where either Z_FIXED is specified, forcing fixed 486 * codes, or when the use of fixed codes is chosen, because that choice 487 * results in a smaller compressed block than dynamic codes. That latter 488 * condition then assures that the above analysis also covers all dynamic 489 * blocks. A dynamic-code block will only be chosen to be emitted if it has 490 * fewer bits than a fixed-code block would for the same set of symbols. 491 * Therefore its average symbol length is assured to be less than 31. So 492 * the compressed data for a dynamic block also cannot overwrite the 493 * symbols from which it is being constructed. 494 */ 495 496 s->pending_buf = (uchf *) ZALLOC(strm, s->lit_bufsize, 4); 497 s->pending_buf_size = (ulg)s->lit_bufsize * 4; 498 499 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 500 s->pending_buf == Z_NULL) { 501 s->status = FINISH_STATE; 502 strm->msg = ERR_MSG(Z_MEM_ERROR); 503 deflateEnd (strm); 504 return Z_MEM_ERROR; 505 } 506 s->sym_buf = s->pending_buf + s->lit_bufsize; 507 s->sym_end = (s->lit_bufsize - 1) * 3; 508 /* We avoid equality with lit_bufsize*3 because of wraparound at 64K 509 * on 16 bit machines and because stored blocks are restricted to 510 * 64K-1 bytes. 511 */ 512 513 s->level = level; 514 s->strategy = strategy; 515 s->method = (Byte)method; 516 517 return deflateReset(strm); 518 } 519 520 /* ========================================================================= 521 * Check for a valid deflate stream state. Return 0 if ok, 1 if not. 522 */ 523 local int deflateStateCheck(z_streamp strm) { 524 deflate_state *s; 525 if (strm == Z_NULL || 526 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) 527 return 1; 528 s = strm->state; 529 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE && 530 #ifdef GZIP 531 s->status != GZIP_STATE && 532 #endif 533 s->status != EXTRA_STATE && 534 s->status != NAME_STATE && 535 s->status != COMMENT_STATE && 536 s->status != HCRC_STATE && 537 s->status != BUSY_STATE && 538 s->status != FINISH_STATE)) 539 return 1; 540 return 0; 541 } 542 543 /* ========================================================================= */ 544 int ZEXPORT deflateSetDictionary(z_streamp strm, const Bytef *dictionary, 545 uInt dictLength) { 546 deflate_state *s; 547 uInt str, n; 548 int wrap; 549 unsigned avail; 550 z_const unsigned char *next; 551 552 if (deflateStateCheck(strm) || dictionary == Z_NULL) 553 return Z_STREAM_ERROR; 554 s = strm->state; 555 wrap = s->wrap; 556 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) 557 return Z_STREAM_ERROR; 558 559 /* when using zlib wrappers, compute Adler-32 for provided dictionary */ 560 if (wrap == 1) 561 strm->adler = adler32(strm->adler, dictionary, dictLength); 562 s->wrap = 0; /* avoid computing Adler-32 in read_buf */ 563 564 /* if dictionary would fill window, just replace the history */ 565 if (dictLength >= s->w_size) { 566 if (wrap == 0) { /* already empty otherwise */ 567 CLEAR_HASH(s); 568 s->strstart = 0; 569 s->block_start = 0L; 570 s->insert = 0; 571 } 572 dictionary += dictLength - s->w_size; /* use the tail */ 573 dictLength = s->w_size; 574 } 575 576 /* insert dictionary into window and hash */ 577 avail = strm->avail_in; 578 next = strm->next_in; 579 strm->avail_in = dictLength; 580 strm->next_in = (z_const Bytef *)dictionary; 581 fill_window(s); 582 while (s->lookahead >= MIN_MATCH) { 583 str = s->strstart; 584 n = s->lookahead - (MIN_MATCH-1); 585 do { 586 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 587 #ifndef FASTEST 588 s->prev[str & s->w_mask] = s->head[s->ins_h]; 589 #endif 590 s->head[s->ins_h] = (Pos)str; 591 str++; 592 } while (--n); 593 s->strstart = str; 594 s->lookahead = MIN_MATCH-1; 595 fill_window(s); 596 } 597 s->strstart += s->lookahead; 598 s->block_start = (long)s->strstart; 599 s->insert = s->lookahead; 600 s->lookahead = 0; 601 s->match_length = s->prev_length = MIN_MATCH-1; 602 s->match_available = 0; 603 strm->next_in = next; 604 strm->avail_in = avail; 605 s->wrap = wrap; 606 return Z_OK; 607 } 608 609 /* ========================================================================= */ 610 int ZEXPORT deflateGetDictionary(z_streamp strm, Bytef *dictionary, 611 uInt *dictLength) { 612 deflate_state *s; 613 uInt len; 614 615 if (deflateStateCheck(strm)) 616 return Z_STREAM_ERROR; 617 s = strm->state; 618 len = s->strstart + s->lookahead; 619 if (len > s->w_size) 620 len = s->w_size; 621 if (dictionary != Z_NULL && len) 622 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len); 623 if (dictLength != Z_NULL) 624 *dictLength = len; 625 return Z_OK; 626 } 627 628 /* ========================================================================= */ 629 int ZEXPORT deflateResetKeep(z_streamp strm) { 630 deflate_state *s; 631 632 if (deflateStateCheck(strm)) { 633 return Z_STREAM_ERROR; 634 } 635 636 strm->total_in = strm->total_out = 0; 637 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 638 strm->data_type = Z_UNKNOWN; 639 640 s = (deflate_state *)strm->state; 641 s->pending = 0; 642 s->pending_out = s->pending_buf; 643 644 if (s->wrap < 0) { 645 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 646 } 647 s->status = 648 #ifdef GZIP 649 s->wrap == 2 ? GZIP_STATE : 650 #endif 651 INIT_STATE; 652 strm->adler = 653 #ifdef GZIP 654 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 655 #endif 656 adler32(0L, Z_NULL, 0); 657 s->last_flush = -2; 658 659 _tr_init(s); 660 661 return Z_OK; 662 } 663 664 /* =========================================================================== 665 * Initialize the "longest match" routines for a new zlib stream 666 */ 667 local void lm_init(deflate_state *s) { 668 s->window_size = (ulg)2L*s->w_size; 669 670 CLEAR_HASH(s); 671 672 /* Set the default configuration parameters: 673 */ 674 s->max_lazy_match = configuration_table[s->level].max_lazy; 675 s->good_match = configuration_table[s->level].good_length; 676 s->nice_match = configuration_table[s->level].nice_length; 677 s->max_chain_length = configuration_table[s->level].max_chain; 678 679 s->strstart = 0; 680 s->block_start = 0L; 681 s->lookahead = 0; 682 s->insert = 0; 683 s->match_length = s->prev_length = MIN_MATCH-1; 684 s->match_available = 0; 685 s->ins_h = 0; 686 } 687 688 /* ========================================================================= */ 689 int ZEXPORT deflateReset(z_streamp strm) { 690 int ret; 691 692 ret = deflateResetKeep(strm); 693 if (ret == Z_OK) 694 lm_init(strm->state); 695 return ret; 696 } 697 698 /* ========================================================================= */ 699 int ZEXPORT deflateSetHeader(z_streamp strm, gz_headerp head) { 700 if (deflateStateCheck(strm) || strm->state->wrap != 2) 701 return Z_STREAM_ERROR; 702 strm->state->gzhead = head; 703 return Z_OK; 704 } 705 706 /* ========================================================================= */ 707 int ZEXPORT deflatePending(z_streamp strm, unsigned *pending, int *bits) { 708 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 709 if (pending != Z_NULL) 710 *pending = strm->state->pending; 711 if (bits != Z_NULL) 712 *bits = strm->state->bi_valid; 713 return Z_OK; 714 } 715 716 /* ========================================================================= */ 717 int ZEXPORT deflatePrime(z_streamp strm, int bits, int value) { 718 deflate_state *s; 719 int put; 720 721 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 722 s = strm->state; 723 if (bits < 0 || bits > 16 || 724 s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3)) 725 return Z_BUF_ERROR; 726 do { 727 put = Buf_size - s->bi_valid; 728 if (put > bits) 729 put = bits; 730 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); 731 s->bi_valid += put; 732 _tr_flush_bits(s); 733 value >>= put; 734 bits -= put; 735 } while (bits); 736 return Z_OK; 737 } 738 739 /* ========================================================================= */ 740 int ZEXPORT deflateParams(z_streamp strm, int level, int strategy) { 741 deflate_state *s; 742 compress_func func; 743 744 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 745 s = strm->state; 746 747 #ifdef FASTEST 748 if (level != 0) level = 1; 749 #else 750 if (level == Z_DEFAULT_COMPRESSION) level = 6; 751 #endif 752 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 753 return Z_STREAM_ERROR; 754 } 755 func = configuration_table[s->level].func; 756 757 if ((strategy != s->strategy || func != configuration_table[level].func) && 758 s->last_flush != -2) { 759 /* Flush the last buffer: */ 760 int err = deflate(strm, Z_BLOCK); 761 if (err == Z_STREAM_ERROR) 762 return err; 763 if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead) 764 return Z_BUF_ERROR; 765 } 766 if (s->level != level) { 767 if (s->level == 0 && s->matches != 0) { 768 if (s->matches == 1) 769 slide_hash(s); 770 else 771 CLEAR_HASH(s); 772 s->matches = 0; 773 } 774 s->level = level; 775 s->max_lazy_match = configuration_table[level].max_lazy; 776 s->good_match = configuration_table[level].good_length; 777 s->nice_match = configuration_table[level].nice_length; 778 s->max_chain_length = configuration_table[level].max_chain; 779 } 780 s->strategy = strategy; 781 return Z_OK; 782 } 783 784 /* ========================================================================= */ 785 int ZEXPORT deflateTune(z_streamp strm, int good_length, int max_lazy, 786 int nice_length, int max_chain) { 787 deflate_state *s; 788 789 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 790 s = strm->state; 791 s->good_match = (uInt)good_length; 792 s->max_lazy_match = (uInt)max_lazy; 793 s->nice_match = nice_length; 794 s->max_chain_length = (uInt)max_chain; 795 return Z_OK; 796 } 797 798 /* ========================================================================= 799 * For the default windowBits of 15 and memLevel of 8, this function returns a 800 * close to exact, as well as small, upper bound on the compressed size. This 801 * is an expansion of ~0.03%, plus a small constant. 802 * 803 * For any setting other than those defaults for windowBits and memLevel, one 804 * of two worst case bounds is returned. This is at most an expansion of ~4% or 805 * ~13%, plus a small constant. 806 * 807 * Both the 0.03% and 4% derive from the overhead of stored blocks. The first 808 * one is for stored blocks of 16383 bytes (memLevel == 8), whereas the second 809 * is for stored blocks of 127 bytes (the worst case memLevel == 1). The 810 * expansion results from five bytes of header for each stored block. 811 * 812 * The larger expansion of 13% results from a window size less than or equal to 813 * the symbols buffer size (windowBits <= memLevel + 7). In that case some of 814 * the data being compressed may have slid out of the sliding window, impeding 815 * a stored block from being emitted. Then the only choice is a fixed or 816 * dynamic block, where a fixed block limits the maximum expansion to 9 bits 817 * per 8-bit byte, plus 10 bits for every block. The smallest block size for 818 * which this can occur is 255 (memLevel == 2). 819 * 820 * Shifts are used to approximate divisions, for speed. 821 */ 822 uLong ZEXPORT deflateBound(z_streamp strm, uLong sourceLen) { 823 deflate_state *s; 824 uLong fixedlen, storelen, wraplen; 825 826 /* upper bound for fixed blocks with 9-bit literals and length 255 827 (memLevel == 2, which is the lowest that may not use stored blocks) -- 828 ~13% overhead plus a small constant */ 829 fixedlen = sourceLen + (sourceLen >> 3) + (sourceLen >> 8) + 830 (sourceLen >> 9) + 4; 831 832 /* upper bound for stored blocks with length 127 (memLevel == 1) -- 833 ~4% overhead plus a small constant */ 834 storelen = sourceLen + (sourceLen >> 5) + (sourceLen >> 7) + 835 (sourceLen >> 11) + 7; 836 837 /* if can't get parameters, return larger bound plus a zlib wrapper */ 838 if (deflateStateCheck(strm)) 839 return (fixedlen > storelen ? fixedlen : storelen) + 6; 840 841 /* compute wrapper length */ 842 s = strm->state; 843 switch (s->wrap) { 844 case 0: /* raw deflate */ 845 wraplen = 0; 846 break; 847 case 1: /* zlib wrapper */ 848 wraplen = 6 + (s->strstart ? 4 : 0); 849 break; 850 #ifdef GZIP 851 case 2: /* gzip wrapper */ 852 wraplen = 18; 853 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 854 Bytef *str; 855 if (s->gzhead->extra != Z_NULL) 856 wraplen += 2 + s->gzhead->extra_len; 857 str = s->gzhead->name; 858 if (str != Z_NULL) 859 do { 860 wraplen++; 861 } while (*str++); 862 str = s->gzhead->comment; 863 if (str != Z_NULL) 864 do { 865 wraplen++; 866 } while (*str++); 867 if (s->gzhead->hcrc) 868 wraplen += 2; 869 } 870 break; 871 #endif 872 default: /* for compiler happiness */ 873 wraplen = 6; 874 } 875 876 /* if not default parameters, return one of the conservative bounds */ 877 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 878 return (s->w_bits <= s->hash_bits && s->level ? fixedlen : storelen) + 879 wraplen; 880 881 /* default settings: return tight bound for that case -- ~0.03% overhead 882 plus a small constant */ 883 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 884 (sourceLen >> 25) + 13 - 6 + wraplen; 885 } 886 887 /* ========================================================================= 888 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 889 * IN assertion: the stream state is correct and there is enough room in 890 * pending_buf. 891 */ 892 local void putShortMSB(deflate_state *s, uInt b) { 893 put_byte(s, (Byte)(b >> 8)); 894 put_byte(s, (Byte)(b & 0xff)); 895 } 896 897 /* ========================================================================= 898 * Flush as much pending output as possible. All deflate() output, except for 899 * some deflate_stored() output, goes through this function so some 900 * applications may wish to modify it to avoid allocating a large 901 * strm->next_out buffer and copying into it. (See also read_buf()). 902 */ 903 local void flush_pending(z_streamp strm) { 904 unsigned len; 905 deflate_state *s = strm->state; 906 907 _tr_flush_bits(s); 908 len = s->pending; 909 if (len > strm->avail_out) len = strm->avail_out; 910 if (len == 0) return; 911 912 zmemcpy(strm->next_out, s->pending_out, len); 913 strm->next_out += len; 914 s->pending_out += len; 915 strm->total_out += len; 916 strm->avail_out -= len; 917 s->pending -= len; 918 if (s->pending == 0) { 919 s->pending_out = s->pending_buf; 920 } 921 } 922 923 /* =========================================================================== 924 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1]. 925 */ 926 #define HCRC_UPDATE(beg) \ 927 do { \ 928 if (s->gzhead->hcrc && s->pending > (beg)) \ 929 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \ 930 s->pending - (beg)); \ 931 } while (0) 932 933 /* ========================================================================= */ 934 int ZEXPORT deflate(z_streamp strm, int flush) { 935 int old_flush; /* value of flush param for previous deflate call */ 936 deflate_state *s; 937 938 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { 939 return Z_STREAM_ERROR; 940 } 941 s = strm->state; 942 943 if (strm->next_out == Z_NULL || 944 (strm->avail_in != 0 && strm->next_in == Z_NULL) || 945 (s->status == FINISH_STATE && flush != Z_FINISH)) { 946 ERR_RETURN(strm, Z_STREAM_ERROR); 947 } 948 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 949 950 old_flush = s->last_flush; 951 s->last_flush = flush; 952 953 /* Flush as much pending output as possible */ 954 if (s->pending != 0) { 955 flush_pending(strm); 956 if (strm->avail_out == 0) { 957 /* Since avail_out is 0, deflate will be called again with 958 * more output space, but possibly with both pending and 959 * avail_in equal to zero. There won't be anything to do, 960 * but this is not an error situation so make sure we 961 * return OK instead of BUF_ERROR at next call of deflate: 962 */ 963 s->last_flush = -1; 964 return Z_OK; 965 } 966 967 /* Make sure there is something to do and avoid duplicate consecutive 968 * flushes. For repeated and useless calls with Z_FINISH, we keep 969 * returning Z_STREAM_END instead of Z_BUF_ERROR. 970 */ 971 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 972 flush != Z_FINISH) { 973 ERR_RETURN(strm, Z_BUF_ERROR); 974 } 975 976 /* User must not provide more input after the first FINISH: */ 977 if (s->status == FINISH_STATE && strm->avail_in != 0) { 978 ERR_RETURN(strm, Z_BUF_ERROR); 979 } 980 981 /* Write the header */ 982 if (s->status == INIT_STATE && s->wrap == 0) 983 s->status = BUSY_STATE; 984 if (s->status == INIT_STATE) { 985 /* zlib header */ 986 uInt header = (Z_DEFLATED + ((s->w_bits - 8) << 4)) << 8; 987 uInt level_flags; 988 989 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 990 level_flags = 0; 991 else if (s->level < 6) 992 level_flags = 1; 993 else if (s->level == 6) 994 level_flags = 2; 995 else 996 level_flags = 3; 997 header |= (level_flags << 6); 998 if (s->strstart != 0) header |= PRESET_DICT; 999 header += 31 - (header % 31); 1000 1001 putShortMSB(s, header); 1002 1003 /* Save the adler32 of the preset dictionary: */ 1004 if (s->strstart != 0) { 1005 putShortMSB(s, (uInt)(strm->adler >> 16)); 1006 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1007 } 1008 strm->adler = adler32(0L, Z_NULL, 0); 1009 s->status = BUSY_STATE; 1010 1011 /* Compression must start with an empty pending buffer */ 1012 flush_pending(strm); 1013 if (s->pending != 0) { 1014 s->last_flush = -1; 1015 return Z_OK; 1016 } 1017 } 1018 #ifdef GZIP 1019 if (s->status == GZIP_STATE) { 1020 /* gzip header */ 1021 strm->adler = crc32(0L, Z_NULL, 0); 1022 put_byte(s, 31); 1023 put_byte(s, 139); 1024 put_byte(s, 8); 1025 if (s->gzhead == Z_NULL) { 1026 put_byte(s, 0); 1027 put_byte(s, 0); 1028 put_byte(s, 0); 1029 put_byte(s, 0); 1030 put_byte(s, 0); 1031 put_byte(s, s->level == 9 ? 2 : 1032 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 1033 4 : 0)); 1034 put_byte(s, OS_CODE); 1035 s->status = BUSY_STATE; 1036 1037 /* Compression must start with an empty pending buffer */ 1038 flush_pending(strm); 1039 if (s->pending != 0) { 1040 s->last_flush = -1; 1041 return Z_OK; 1042 } 1043 } 1044 else { 1045 put_byte(s, (s->gzhead->text ? 1 : 0) + 1046 (s->gzhead->hcrc ? 2 : 0) + 1047 (s->gzhead->extra == Z_NULL ? 0 : 4) + 1048 (s->gzhead->name == Z_NULL ? 0 : 8) + 1049 (s->gzhead->comment == Z_NULL ? 0 : 16) 1050 ); 1051 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 1052 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 1053 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 1054 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 1055 put_byte(s, s->level == 9 ? 2 : 1056 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 1057 4 : 0)); 1058 put_byte(s, s->gzhead->os & 0xff); 1059 if (s->gzhead->extra != Z_NULL) { 1060 put_byte(s, s->gzhead->extra_len & 0xff); 1061 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 1062 } 1063 if (s->gzhead->hcrc) 1064 strm->adler = crc32(strm->adler, s->pending_buf, 1065 s->pending); 1066 s->gzindex = 0; 1067 s->status = EXTRA_STATE; 1068 } 1069 } 1070 if (s->status == EXTRA_STATE) { 1071 if (s->gzhead->extra != Z_NULL) { 1072 ulg beg = s->pending; /* start of bytes to update crc */ 1073 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex; 1074 while (s->pending + left > s->pending_buf_size) { 1075 uInt copy = s->pending_buf_size - s->pending; 1076 zmemcpy(s->pending_buf + s->pending, 1077 s->gzhead->extra + s->gzindex, copy); 1078 s->pending = s->pending_buf_size; 1079 HCRC_UPDATE(beg); 1080 s->gzindex += copy; 1081 flush_pending(strm); 1082 if (s->pending != 0) { 1083 s->last_flush = -1; 1084 return Z_OK; 1085 } 1086 beg = 0; 1087 left -= copy; 1088 } 1089 zmemcpy(s->pending_buf + s->pending, 1090 s->gzhead->extra + s->gzindex, left); 1091 s->pending += left; 1092 HCRC_UPDATE(beg); 1093 s->gzindex = 0; 1094 } 1095 s->status = NAME_STATE; 1096 } 1097 if (s->status == NAME_STATE) { 1098 if (s->gzhead->name != Z_NULL) { 1099 ulg beg = s->pending; /* start of bytes to update crc */ 1100 int val; 1101 do { 1102 if (s->pending == s->pending_buf_size) { 1103 HCRC_UPDATE(beg); 1104 flush_pending(strm); 1105 if (s->pending != 0) { 1106 s->last_flush = -1; 1107 return Z_OK; 1108 } 1109 beg = 0; 1110 } 1111 val = s->gzhead->name[s->gzindex++]; 1112 put_byte(s, val); 1113 } while (val != 0); 1114 HCRC_UPDATE(beg); 1115 s->gzindex = 0; 1116 } 1117 s->status = COMMENT_STATE; 1118 } 1119 if (s->status == COMMENT_STATE) { 1120 if (s->gzhead->comment != Z_NULL) { 1121 ulg beg = s->pending; /* start of bytes to update crc */ 1122 int val; 1123 do { 1124 if (s->pending == s->pending_buf_size) { 1125 HCRC_UPDATE(beg); 1126 flush_pending(strm); 1127 if (s->pending != 0) { 1128 s->last_flush = -1; 1129 return Z_OK; 1130 } 1131 beg = 0; 1132 } 1133 val = s->gzhead->comment[s->gzindex++]; 1134 put_byte(s, val); 1135 } while (val != 0); 1136 HCRC_UPDATE(beg); 1137 } 1138 s->status = HCRC_STATE; 1139 } 1140 if (s->status == HCRC_STATE) { 1141 if (s->gzhead->hcrc) { 1142 if (s->pending + 2 > s->pending_buf_size) { 1143 flush_pending(strm); 1144 if (s->pending != 0) { 1145 s->last_flush = -1; 1146 return Z_OK; 1147 } 1148 } 1149 put_byte(s, (Byte)(strm->adler & 0xff)); 1150 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1151 strm->adler = crc32(0L, Z_NULL, 0); 1152 } 1153 s->status = BUSY_STATE; 1154 1155 /* Compression must start with an empty pending buffer */ 1156 flush_pending(strm); 1157 if (s->pending != 0) { 1158 s->last_flush = -1; 1159 return Z_OK; 1160 } 1161 } 1162 #endif 1163 1164 /* Start a new block or continue the current one. 1165 */ 1166 if (strm->avail_in != 0 || s->lookahead != 0 || 1167 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 1168 block_state bstate; 1169 1170 bstate = s->level == 0 ? deflate_stored(s, flush) : 1171 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 1172 s->strategy == Z_RLE ? deflate_rle(s, flush) : 1173 (*(configuration_table[s->level].func))(s, flush); 1174 1175 if (bstate == finish_started || bstate == finish_done) { 1176 s->status = FINISH_STATE; 1177 } 1178 if (bstate == need_more || bstate == finish_started) { 1179 if (strm->avail_out == 0) { 1180 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 1181 } 1182 return Z_OK; 1183 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 1184 * of deflate should use the same flush parameter to make sure 1185 * that the flush is complete. So we don't have to output an 1186 * empty block here, this will be done at next call. This also 1187 * ensures that for a very small output buffer, we emit at most 1188 * one empty block. 1189 */ 1190 } 1191 if (bstate == block_done) { 1192 if (flush == Z_PARTIAL_FLUSH) { 1193 _tr_align(s); 1194 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 1195 _tr_stored_block(s, (char*)0, 0L, 0); 1196 /* For a full flush, this empty block will be recognized 1197 * as a special marker by inflate_sync(). 1198 */ 1199 if (flush == Z_FULL_FLUSH) { 1200 CLEAR_HASH(s); /* forget history */ 1201 if (s->lookahead == 0) { 1202 s->strstart = 0; 1203 s->block_start = 0L; 1204 s->insert = 0; 1205 } 1206 } 1207 } 1208 flush_pending(strm); 1209 if (strm->avail_out == 0) { 1210 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 1211 return Z_OK; 1212 } 1213 } 1214 } 1215 1216 if (flush != Z_FINISH) return Z_OK; 1217 if (s->wrap <= 0) return Z_STREAM_END; 1218 1219 /* Write the trailer */ 1220 #ifdef GZIP 1221 if (s->wrap == 2) { 1222 put_byte(s, (Byte)(strm->adler & 0xff)); 1223 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1224 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 1225 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 1226 put_byte(s, (Byte)(strm->total_in & 0xff)); 1227 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 1228 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 1229 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 1230 } 1231 else 1232 #endif 1233 { 1234 putShortMSB(s, (uInt)(strm->adler >> 16)); 1235 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1236 } 1237 flush_pending(strm); 1238 /* If avail_out is zero, the application will call deflate again 1239 * to flush the rest. 1240 */ 1241 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 1242 return s->pending != 0 ? Z_OK : Z_STREAM_END; 1243 } 1244 1245 /* ========================================================================= */ 1246 int ZEXPORT deflateEnd(z_streamp strm) { 1247 int status; 1248 1249 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 1250 1251 status = strm->state->status; 1252 1253 /* Deallocate in reverse order of allocations: */ 1254 TRY_FREE(strm, strm->state->pending_buf); 1255 TRY_FREE(strm, strm->state->head); 1256 TRY_FREE(strm, strm->state->prev); 1257 TRY_FREE(strm, strm->state->window); 1258 1259 ZFREE(strm, strm->state); 1260 strm->state = Z_NULL; 1261 1262 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1263 } 1264 1265 /* ========================================================================= 1266 * Copy the source state to the destination state. 1267 * To simplify the source, this is not supported for 16-bit MSDOS (which 1268 * doesn't have enough memory anyway to duplicate compression states). 1269 */ 1270 int ZEXPORT deflateCopy(z_streamp dest, z_streamp source) { 1271 #ifdef MAXSEG_64K 1272 (void)dest; 1273 (void)source; 1274 return Z_STREAM_ERROR; 1275 #else 1276 deflate_state *ds; 1277 deflate_state *ss; 1278 1279 1280 if (deflateStateCheck(source) || dest == Z_NULL) { 1281 return Z_STREAM_ERROR; 1282 } 1283 1284 ss = source->state; 1285 1286 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream)); 1287 1288 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1289 if (ds == Z_NULL) return Z_MEM_ERROR; 1290 dest->state = (struct internal_state FAR *) ds; 1291 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state)); 1292 ds->strm = dest; 1293 1294 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1295 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1296 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1297 ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, 4); 1298 1299 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1300 ds->pending_buf == Z_NULL) { 1301 deflateEnd (dest); 1302 return Z_MEM_ERROR; 1303 } 1304 /* following zmemcpy do not work for 16-bit MSDOS */ 1305 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1306 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos)); 1307 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos)); 1308 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); 1309 1310 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1311 ds->sym_buf = ds->pending_buf + ds->lit_bufsize; 1312 1313 ds->l_desc.dyn_tree = ds->dyn_ltree; 1314 ds->d_desc.dyn_tree = ds->dyn_dtree; 1315 ds->bl_desc.dyn_tree = ds->bl_tree; 1316 1317 return Z_OK; 1318 #endif /* MAXSEG_64K */ 1319 } 1320 1321 #ifndef FASTEST 1322 /* =========================================================================== 1323 * Set match_start to the longest match starting at the given string and 1324 * return its length. Matches shorter or equal to prev_length are discarded, 1325 * in which case the result is equal to prev_length and match_start is 1326 * garbage. 1327 * IN assertions: cur_match is the head of the hash chain for the current 1328 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1329 * OUT assertion: the match length is not greater than s->lookahead. 1330 */ 1331 local uInt longest_match(deflate_state *s, IPos cur_match) { 1332 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1333 register Bytef *scan = s->window + s->strstart; /* current string */ 1334 register Bytef *match; /* matched string */ 1335 register int len; /* length of current match */ 1336 int best_len = (int)s->prev_length; /* best match length so far */ 1337 int nice_match = s->nice_match; /* stop if match long enough */ 1338 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1339 s->strstart - (IPos)MAX_DIST(s) : NIL; 1340 /* Stop when cur_match becomes <= limit. To simplify the code, 1341 * we prevent matches with the string of window index 0. 1342 */ 1343 Posf *prev = s->prev; 1344 uInt wmask = s->w_mask; 1345 1346 #ifdef UNALIGNED_OK 1347 /* Compare two bytes at a time. Note: this is not always beneficial. 1348 * Try with and without -DUNALIGNED_OK to check. 1349 */ 1350 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1351 register ush scan_start = *(ushf*)scan; 1352 register ush scan_end = *(ushf*)(scan + best_len - 1); 1353 #else 1354 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1355 register Byte scan_end1 = scan[best_len - 1]; 1356 register Byte scan_end = scan[best_len]; 1357 #endif 1358 1359 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1360 * It is easy to get rid of this optimization if necessary. 1361 */ 1362 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1363 1364 /* Do not waste too much time if we already have a good match: */ 1365 if (s->prev_length >= s->good_match) { 1366 chain_length >>= 2; 1367 } 1368 /* Do not look for matches beyond the end of the input. This is necessary 1369 * to make deflate deterministic. 1370 */ 1371 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead; 1372 1373 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1374 "need lookahead"); 1375 1376 do { 1377 Assert(cur_match < s->strstart, "no future"); 1378 match = s->window + cur_match; 1379 1380 /* Skip to next match if the match length cannot increase 1381 * or if the match length is less than 2. Note that the checks below 1382 * for insufficient lookahead only occur occasionally for performance 1383 * reasons. Therefore uninitialized memory will be accessed, and 1384 * conditional jumps will be made that depend on those values. 1385 * However the length of the match is limited to the lookahead, so 1386 * the output of deflate is not affected by the uninitialized values. 1387 */ 1388 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1389 /* This code assumes sizeof(unsigned short) == 2. Do not use 1390 * UNALIGNED_OK if your compiler uses a different size. 1391 */ 1392 if (*(ushf*)(match + best_len - 1) != scan_end || 1393 *(ushf*)match != scan_start) continue; 1394 1395 /* It is not necessary to compare scan[2] and match[2] since they are 1396 * always equal when the other bytes match, given that the hash keys 1397 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1398 * strstart + 3, + 5, up to strstart + 257. We check for insufficient 1399 * lookahead only every 4th comparison; the 128th check will be made 1400 * at strstart + 257. If MAX_MATCH-2 is not a multiple of 8, it is 1401 * necessary to put more guard bytes at the end of the window, or 1402 * to check more often for insufficient lookahead. 1403 */ 1404 Assert(scan[2] == match[2], "scan[2]?"); 1405 scan++, match++; 1406 do { 1407 } while (*(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1408 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1409 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1410 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1411 scan < strend); 1412 /* The funny "do {}" generates better code on most compilers */ 1413 1414 /* Here, scan <= window + strstart + 257 */ 1415 Assert(scan <= s->window + (unsigned)(s->window_size - 1), 1416 "wild scan"); 1417 if (*scan == *match) scan++; 1418 1419 len = (MAX_MATCH - 1) - (int)(strend - scan); 1420 scan = strend - (MAX_MATCH-1); 1421 1422 #else /* UNALIGNED_OK */ 1423 1424 if (match[best_len] != scan_end || 1425 match[best_len - 1] != scan_end1 || 1426 *match != *scan || 1427 *++match != scan[1]) continue; 1428 1429 /* The check at best_len - 1 can be removed because it will be made 1430 * again later. (This heuristic is not always a win.) 1431 * It is not necessary to compare scan[2] and match[2] since they 1432 * are always equal when the other bytes match, given that 1433 * the hash keys are equal and that HASH_BITS >= 8. 1434 */ 1435 scan += 2, match++; 1436 Assert(*scan == *match, "match[2]?"); 1437 1438 /* We check for insufficient lookahead only every 8th comparison; 1439 * the 256th check will be made at strstart + 258. 1440 */ 1441 do { 1442 } while (*++scan == *++match && *++scan == *++match && 1443 *++scan == *++match && *++scan == *++match && 1444 *++scan == *++match && *++scan == *++match && 1445 *++scan == *++match && *++scan == *++match && 1446 scan < strend); 1447 1448 Assert(scan <= s->window + (unsigned)(s->window_size - 1), 1449 "wild scan"); 1450 1451 len = MAX_MATCH - (int)(strend - scan); 1452 scan = strend - MAX_MATCH; 1453 1454 #endif /* UNALIGNED_OK */ 1455 1456 if (len > best_len) { 1457 s->match_start = cur_match; 1458 best_len = len; 1459 if (len >= nice_match) break; 1460 #ifdef UNALIGNED_OK 1461 scan_end = *(ushf*)(scan + best_len - 1); 1462 #else 1463 scan_end1 = scan[best_len - 1]; 1464 scan_end = scan[best_len]; 1465 #endif 1466 } 1467 } while ((cur_match = prev[cur_match & wmask]) > limit 1468 && --chain_length != 0); 1469 1470 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1471 return s->lookahead; 1472 } 1473 1474 #else /* FASTEST */ 1475 1476 /* --------------------------------------------------------------------------- 1477 * Optimized version for FASTEST only 1478 */ 1479 local uInt longest_match(deflate_state *s, IPos cur_match) { 1480 register Bytef *scan = s->window + s->strstart; /* current string */ 1481 register Bytef *match; /* matched string */ 1482 register int len; /* length of current match */ 1483 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1484 1485 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1486 * It is easy to get rid of this optimization if necessary. 1487 */ 1488 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1489 1490 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1491 "need lookahead"); 1492 1493 Assert(cur_match < s->strstart, "no future"); 1494 1495 match = s->window + cur_match; 1496 1497 /* Return failure if the match length is less than 2: 1498 */ 1499 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1500 1501 /* The check at best_len - 1 can be removed because it will be made 1502 * again later. (This heuristic is not always a win.) 1503 * It is not necessary to compare scan[2] and match[2] since they 1504 * are always equal when the other bytes match, given that 1505 * the hash keys are equal and that HASH_BITS >= 8. 1506 */ 1507 scan += 2, match += 2; 1508 Assert(*scan == *match, "match[2]?"); 1509 1510 /* We check for insufficient lookahead only every 8th comparison; 1511 * the 256th check will be made at strstart + 258. 1512 */ 1513 do { 1514 } while (*++scan == *++match && *++scan == *++match && 1515 *++scan == *++match && *++scan == *++match && 1516 *++scan == *++match && *++scan == *++match && 1517 *++scan == *++match && *++scan == *++match && 1518 scan < strend); 1519 1520 Assert(scan <= s->window + (unsigned)(s->window_size - 1), "wild scan"); 1521 1522 len = MAX_MATCH - (int)(strend - scan); 1523 1524 if (len < MIN_MATCH) return MIN_MATCH - 1; 1525 1526 s->match_start = cur_match; 1527 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1528 } 1529 1530 #endif /* FASTEST */ 1531 1532 #ifdef ZLIB_DEBUG 1533 1534 #define EQUAL 0 1535 /* result of memcmp for equal strings */ 1536 1537 /* =========================================================================== 1538 * Check that the match at match_start is indeed a match. 1539 */ 1540 local void check_match(deflate_state *s, IPos start, IPos match, int length) { 1541 /* check that the match is indeed a match */ 1542 if (zmemcmp(s->window + match, 1543 s->window + start, length) != EQUAL) { 1544 fprintf(stderr, " start %u, match %u, length %d\n", 1545 start, match, length); 1546 do { 1547 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); 1548 } while (--length != 0); 1549 z_error("invalid match"); 1550 } 1551 if (z_verbose > 1) { 1552 fprintf(stderr,"\\[%d,%d]", start - match, length); 1553 do { putc(s->window[start++], stderr); } while (--length != 0); 1554 } 1555 } 1556 #else 1557 # define check_match(s, start, match, length) 1558 #endif /* ZLIB_DEBUG */ 1559 1560 /* =========================================================================== 1561 * Flush the current block, with given end-of-file flag. 1562 * IN assertion: strstart is set to the end of the current match. 1563 */ 1564 #define FLUSH_BLOCK_ONLY(s, last) { \ 1565 _tr_flush_block(s, (s->block_start >= 0L ? \ 1566 (charf *)&s->window[(unsigned)s->block_start] : \ 1567 (charf *)Z_NULL), \ 1568 (ulg)((long)s->strstart - s->block_start), \ 1569 (last)); \ 1570 s->block_start = s->strstart; \ 1571 flush_pending(s->strm); \ 1572 Tracev((stderr,"[FLUSH]")); \ 1573 } 1574 1575 /* Same but force premature exit if necessary. */ 1576 #define FLUSH_BLOCK(s, last) { \ 1577 FLUSH_BLOCK_ONLY(s, last); \ 1578 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1579 } 1580 1581 /* Maximum stored block length in deflate format (not including header). */ 1582 #define MAX_STORED 65535 1583 1584 #if !defined(MIN) 1585 /* Minimum of a and b. */ 1586 #define MIN(a, b) ((a) > (b) ? (b) : (a)) 1587 #endif 1588 1589 /* =========================================================================== 1590 * Copy without compression as much as possible from the input stream, return 1591 * the current block state. 1592 * 1593 * In case deflateParams() is used to later switch to a non-zero compression 1594 * level, s->matches (otherwise unused when storing) keeps track of the number 1595 * of hash table slides to perform. If s->matches is 1, then one hash table 1596 * slide will be done when switching. If s->matches is 2, the maximum value 1597 * allowed here, then the hash table will be cleared, since two or more slides 1598 * is the same as a clear. 1599 * 1600 * deflate_stored() is written to minimize the number of times an input byte is 1601 * copied. It is most efficient with large input and output buffers, which 1602 * maximizes the opportunities to have a single copy from next_in to next_out. 1603 */ 1604 local block_state deflate_stored(deflate_state *s, int flush) { 1605 /* Smallest worthy block size when not flushing or finishing. By default 1606 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For 1607 * large input and output buffers, the stored block size will be larger. 1608 */ 1609 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size); 1610 1611 /* Copy as many min_block or larger stored blocks directly to next_out as 1612 * possible. If flushing, copy the remaining available input to next_out as 1613 * stored blocks, if there is enough space. 1614 */ 1615 unsigned len, left, have, last = 0; 1616 unsigned used = s->strm->avail_in; 1617 do { 1618 /* Set len to the maximum size block that we can copy directly with the 1619 * available input data and output space. Set left to how much of that 1620 * would be copied from what's left in the window. 1621 */ 1622 len = MAX_STORED; /* maximum deflate stored block length */ 1623 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1624 if (s->strm->avail_out < have) /* need room for header */ 1625 break; 1626 /* maximum stored block length that will fit in avail_out: */ 1627 have = s->strm->avail_out - have; 1628 left = s->strstart - s->block_start; /* bytes left in window */ 1629 if (len > (ulg)left + s->strm->avail_in) 1630 len = left + s->strm->avail_in; /* limit len to the input */ 1631 if (len > have) 1632 len = have; /* limit len to the output */ 1633 1634 /* If the stored block would be less than min_block in length, or if 1635 * unable to copy all of the available input when flushing, then try 1636 * copying to the window and the pending buffer instead. Also don't 1637 * write an empty block when flushing -- deflate() does that. 1638 */ 1639 if (len < min_block && ((len == 0 && flush != Z_FINISH) || 1640 flush == Z_NO_FLUSH || 1641 len != left + s->strm->avail_in)) 1642 break; 1643 1644 /* Make a dummy stored block in pending to get the header bytes, 1645 * including any pending bits. This also updates the debugging counts. 1646 */ 1647 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0; 1648 _tr_stored_block(s, (char *)0, 0L, last); 1649 1650 /* Replace the lengths in the dummy stored block with len. */ 1651 s->pending_buf[s->pending - 4] = len; 1652 s->pending_buf[s->pending - 3] = len >> 8; 1653 s->pending_buf[s->pending - 2] = ~len; 1654 s->pending_buf[s->pending - 1] = ~len >> 8; 1655 1656 /* Write the stored block header bytes. */ 1657 flush_pending(s->strm); 1658 1659 #ifdef ZLIB_DEBUG 1660 /* Update debugging counts for the data about to be copied. */ 1661 s->compressed_len += len << 3; 1662 s->bits_sent += len << 3; 1663 #endif 1664 1665 /* Copy uncompressed bytes from the window to next_out. */ 1666 if (left) { 1667 if (left > len) 1668 left = len; 1669 zmemcpy(s->strm->next_out, s->window + s->block_start, left); 1670 s->strm->next_out += left; 1671 s->strm->avail_out -= left; 1672 s->strm->total_out += left; 1673 s->block_start += left; 1674 len -= left; 1675 } 1676 1677 /* Copy uncompressed bytes directly from next_in to next_out, updating 1678 * the check value. 1679 */ 1680 if (len) { 1681 read_buf(s->strm, s->strm->next_out, len); 1682 s->strm->next_out += len; 1683 s->strm->avail_out -= len; 1684 s->strm->total_out += len; 1685 } 1686 } while (last == 0); 1687 1688 /* Update the sliding window with the last s->w_size bytes of the copied 1689 * data, or append all of the copied data to the existing window if less 1690 * than s->w_size bytes were copied. Also update the number of bytes to 1691 * insert in the hash tables, in the event that deflateParams() switches to 1692 * a non-zero compression level. 1693 */ 1694 used -= s->strm->avail_in; /* number of input bytes directly copied */ 1695 if (used) { 1696 /* If any input was used, then no unused input remains in the window, 1697 * therefore s->block_start == s->strstart. 1698 */ 1699 if (used >= s->w_size) { /* supplant the previous history */ 1700 s->matches = 2; /* clear hash */ 1701 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size); 1702 s->strstart = s->w_size; 1703 s->insert = s->strstart; 1704 } 1705 else { 1706 if (s->window_size - s->strstart <= used) { 1707 /* Slide the window down. */ 1708 s->strstart -= s->w_size; 1709 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1710 if (s->matches < 2) 1711 s->matches++; /* add a pending slide_hash() */ 1712 if (s->insert > s->strstart) 1713 s->insert = s->strstart; 1714 } 1715 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used); 1716 s->strstart += used; 1717 s->insert += MIN(used, s->w_size - s->insert); 1718 } 1719 s->block_start = s->strstart; 1720 } 1721 if (s->high_water < s->strstart) 1722 s->high_water = s->strstart; 1723 1724 /* If the last block was written to next_out, then done. */ 1725 if (last) 1726 return finish_done; 1727 1728 /* If flushing and all input has been consumed, then done. */ 1729 if (flush != Z_NO_FLUSH && flush != Z_FINISH && 1730 s->strm->avail_in == 0 && (long)s->strstart == s->block_start) 1731 return block_done; 1732 1733 /* Fill the window with any remaining input. */ 1734 have = s->window_size - s->strstart; 1735 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) { 1736 /* Slide the window down. */ 1737 s->block_start -= s->w_size; 1738 s->strstart -= s->w_size; 1739 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1740 if (s->matches < 2) 1741 s->matches++; /* add a pending slide_hash() */ 1742 have += s->w_size; /* more space now */ 1743 if (s->insert > s->strstart) 1744 s->insert = s->strstart; 1745 } 1746 if (have > s->strm->avail_in) 1747 have = s->strm->avail_in; 1748 if (have) { 1749 read_buf(s->strm, s->window + s->strstart, have); 1750 s->strstart += have; 1751 s->insert += MIN(have, s->w_size - s->insert); 1752 } 1753 if (s->high_water < s->strstart) 1754 s->high_water = s->strstart; 1755 1756 /* There was not enough avail_out to write a complete worthy or flushed 1757 * stored block to next_out. Write a stored block to pending instead, if we 1758 * have enough input for a worthy block, or if flushing and there is enough 1759 * room for the remaining input as a stored block in the pending buffer. 1760 */ 1761 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1762 /* maximum stored block length that will fit in pending: */ 1763 have = MIN(s->pending_buf_size - have, MAX_STORED); 1764 min_block = MIN(have, s->w_size); 1765 left = s->strstart - s->block_start; 1766 if (left >= min_block || 1767 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH && 1768 s->strm->avail_in == 0 && left <= have)) { 1769 len = MIN(left, have); 1770 last = flush == Z_FINISH && s->strm->avail_in == 0 && 1771 len == left ? 1 : 0; 1772 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last); 1773 s->block_start += len; 1774 flush_pending(s->strm); 1775 } 1776 1777 /* We've done all we can with the available input and output. */ 1778 return last ? finish_started : need_more; 1779 } 1780 1781 /* =========================================================================== 1782 * Compress as much as possible from the input stream, return the current 1783 * block state. 1784 * This function does not perform lazy evaluation of matches and inserts 1785 * new strings in the dictionary only for unmatched strings or for short 1786 * matches. It is used only for the fast compression options. 1787 */ 1788 local block_state deflate_fast(deflate_state *s, int flush) { 1789 IPos hash_head; /* head of the hash chain */ 1790 int bflush; /* set if current block must be flushed */ 1791 1792 for (;;) { 1793 /* Make sure that we always have enough lookahead, except 1794 * at the end of the input file. We need MAX_MATCH bytes 1795 * for the next match, plus MIN_MATCH bytes to insert the 1796 * string following the next match. 1797 */ 1798 if (s->lookahead < MIN_LOOKAHEAD) { 1799 fill_window(s); 1800 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1801 return need_more; 1802 } 1803 if (s->lookahead == 0) break; /* flush the current block */ 1804 } 1805 1806 /* Insert the string window[strstart .. strstart + 2] in the 1807 * dictionary, and set hash_head to the head of the hash chain: 1808 */ 1809 hash_head = NIL; 1810 if (s->lookahead >= MIN_MATCH) { 1811 INSERT_STRING(s, s->strstart, hash_head); 1812 } 1813 1814 /* Find the longest match, discarding those <= prev_length. 1815 * At this point we have always match_length < MIN_MATCH 1816 */ 1817 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1818 /* To simplify the code, we prevent matches with the string 1819 * of window index 0 (in particular we have to avoid a match 1820 * of the string with itself at the start of the input file). 1821 */ 1822 s->match_length = longest_match (s, hash_head); 1823 /* longest_match() sets match_start */ 1824 } 1825 if (s->match_length >= MIN_MATCH) { 1826 check_match(s, s->strstart, s->match_start, s->match_length); 1827 1828 _tr_tally_dist(s, s->strstart - s->match_start, 1829 s->match_length - MIN_MATCH, bflush); 1830 1831 s->lookahead -= s->match_length; 1832 1833 /* Insert new strings in the hash table only if the match length 1834 * is not too large. This saves time but degrades compression. 1835 */ 1836 #ifndef FASTEST 1837 if (s->match_length <= s->max_insert_length && 1838 s->lookahead >= MIN_MATCH) { 1839 s->match_length--; /* string at strstart already in table */ 1840 do { 1841 s->strstart++; 1842 INSERT_STRING(s, s->strstart, hash_head); 1843 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1844 * always MIN_MATCH bytes ahead. 1845 */ 1846 } while (--s->match_length != 0); 1847 s->strstart++; 1848 } else 1849 #endif 1850 { 1851 s->strstart += s->match_length; 1852 s->match_length = 0; 1853 s->ins_h = s->window[s->strstart]; 1854 UPDATE_HASH(s, s->ins_h, s->window[s->strstart + 1]); 1855 #if MIN_MATCH != 3 1856 Call UPDATE_HASH() MIN_MATCH-3 more times 1857 #endif 1858 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1859 * matter since it will be recomputed at next deflate call. 1860 */ 1861 } 1862 } else { 1863 /* No match, output a literal byte */ 1864 Tracevv((stderr,"%c", s->window[s->strstart])); 1865 _tr_tally_lit(s, s->window[s->strstart], bflush); 1866 s->lookahead--; 1867 s->strstart++; 1868 } 1869 if (bflush) FLUSH_BLOCK(s, 0); 1870 } 1871 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1872 if (flush == Z_FINISH) { 1873 FLUSH_BLOCK(s, 1); 1874 return finish_done; 1875 } 1876 if (s->sym_next) 1877 FLUSH_BLOCK(s, 0); 1878 return block_done; 1879 } 1880 1881 #ifndef FASTEST 1882 /* =========================================================================== 1883 * Same as above, but achieves better compression. We use a lazy 1884 * evaluation for matches: a match is finally adopted only if there is 1885 * no better match at the next window position. 1886 */ 1887 local block_state deflate_slow(deflate_state *s, int flush) { 1888 IPos hash_head; /* head of hash chain */ 1889 int bflush; /* set if current block must be flushed */ 1890 1891 /* Process the input block. */ 1892 for (;;) { 1893 /* Make sure that we always have enough lookahead, except 1894 * at the end of the input file. We need MAX_MATCH bytes 1895 * for the next match, plus MIN_MATCH bytes to insert the 1896 * string following the next match. 1897 */ 1898 if (s->lookahead < MIN_LOOKAHEAD) { 1899 fill_window(s); 1900 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1901 return need_more; 1902 } 1903 if (s->lookahead == 0) break; /* flush the current block */ 1904 } 1905 1906 /* Insert the string window[strstart .. strstart + 2] in the 1907 * dictionary, and set hash_head to the head of the hash chain: 1908 */ 1909 hash_head = NIL; 1910 if (s->lookahead >= MIN_MATCH) { 1911 INSERT_STRING(s, s->strstart, hash_head); 1912 } 1913 1914 /* Find the longest match, discarding those <= prev_length. 1915 */ 1916 s->prev_length = s->match_length, s->prev_match = s->match_start; 1917 s->match_length = MIN_MATCH-1; 1918 1919 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1920 s->strstart - hash_head <= MAX_DIST(s)) { 1921 /* To simplify the code, we prevent matches with the string 1922 * of window index 0 (in particular we have to avoid a match 1923 * of the string with itself at the start of the input file). 1924 */ 1925 s->match_length = longest_match (s, hash_head); 1926 /* longest_match() sets match_start */ 1927 1928 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1929 #if TOO_FAR <= 32767 1930 || (s->match_length == MIN_MATCH && 1931 s->strstart - s->match_start > TOO_FAR) 1932 #endif 1933 )) { 1934 1935 /* If prev_match is also MIN_MATCH, match_start is garbage 1936 * but we will ignore the current match anyway. 1937 */ 1938 s->match_length = MIN_MATCH-1; 1939 } 1940 } 1941 /* If there was a match at the previous step and the current 1942 * match is not better, output the previous match: 1943 */ 1944 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1945 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1946 /* Do not insert strings in hash table beyond this. */ 1947 1948 check_match(s, s->strstart - 1, s->prev_match, s->prev_length); 1949 1950 _tr_tally_dist(s, s->strstart - 1 - s->prev_match, 1951 s->prev_length - MIN_MATCH, bflush); 1952 1953 /* Insert in hash table all strings up to the end of the match. 1954 * strstart - 1 and strstart are already inserted. If there is not 1955 * enough lookahead, the last two strings are not inserted in 1956 * the hash table. 1957 */ 1958 s->lookahead -= s->prev_length - 1; 1959 s->prev_length -= 2; 1960 do { 1961 if (++s->strstart <= max_insert) { 1962 INSERT_STRING(s, s->strstart, hash_head); 1963 } 1964 } while (--s->prev_length != 0); 1965 s->match_available = 0; 1966 s->match_length = MIN_MATCH-1; 1967 s->strstart++; 1968 1969 if (bflush) FLUSH_BLOCK(s, 0); 1970 1971 } else if (s->match_available) { 1972 /* If there was no match at the previous position, output a 1973 * single literal. If there was a match but the current match 1974 * is longer, truncate the previous match to a single literal. 1975 */ 1976 Tracevv((stderr,"%c", s->window[s->strstart - 1])); 1977 _tr_tally_lit(s, s->window[s->strstart - 1], bflush); 1978 if (bflush) { 1979 FLUSH_BLOCK_ONLY(s, 0); 1980 } 1981 s->strstart++; 1982 s->lookahead--; 1983 if (s->strm->avail_out == 0) return need_more; 1984 } else { 1985 /* There is no previous match to compare with, wait for 1986 * the next step to decide. 1987 */ 1988 s->match_available = 1; 1989 s->strstart++; 1990 s->lookahead--; 1991 } 1992 } 1993 Assert (flush != Z_NO_FLUSH, "no flush?"); 1994 if (s->match_available) { 1995 Tracevv((stderr,"%c", s->window[s->strstart - 1])); 1996 _tr_tally_lit(s, s->window[s->strstart - 1], bflush); 1997 s->match_available = 0; 1998 } 1999 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 2000 if (flush == Z_FINISH) { 2001 FLUSH_BLOCK(s, 1); 2002 return finish_done; 2003 } 2004 if (s->sym_next) 2005 FLUSH_BLOCK(s, 0); 2006 return block_done; 2007 } 2008 #endif /* FASTEST */ 2009 2010 /* =========================================================================== 2011 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 2012 * one. Do not maintain a hash table. (It will be regenerated if this run of 2013 * deflate switches away from Z_RLE.) 2014 */ 2015 local block_state deflate_rle(deflate_state *s, int flush) { 2016 int bflush; /* set if current block must be flushed */ 2017 uInt prev; /* byte at distance one to match */ 2018 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 2019 2020 for (;;) { 2021 /* Make sure that we always have enough lookahead, except 2022 * at the end of the input file. We need MAX_MATCH bytes 2023 * for the longest run, plus one for the unrolled loop. 2024 */ 2025 if (s->lookahead <= MAX_MATCH) { 2026 fill_window(s); 2027 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 2028 return need_more; 2029 } 2030 if (s->lookahead == 0) break; /* flush the current block */ 2031 } 2032 2033 /* See how many times the previous byte repeats */ 2034 s->match_length = 0; 2035 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 2036 scan = s->window + s->strstart - 1; 2037 prev = *scan; 2038 if (prev == *++scan && prev == *++scan && prev == *++scan) { 2039 strend = s->window + s->strstart + MAX_MATCH; 2040 do { 2041 } while (prev == *++scan && prev == *++scan && 2042 prev == *++scan && prev == *++scan && 2043 prev == *++scan && prev == *++scan && 2044 prev == *++scan && prev == *++scan && 2045 scan < strend); 2046 s->match_length = MAX_MATCH - (uInt)(strend - scan); 2047 if (s->match_length > s->lookahead) 2048 s->match_length = s->lookahead; 2049 } 2050 Assert(scan <= s->window + (uInt)(s->window_size - 1), 2051 "wild scan"); 2052 } 2053 2054 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 2055 if (s->match_length >= MIN_MATCH) { 2056 check_match(s, s->strstart, s->strstart - 1, s->match_length); 2057 2058 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 2059 2060 s->lookahead -= s->match_length; 2061 s->strstart += s->match_length; 2062 s->match_length = 0; 2063 } else { 2064 /* No match, output a literal byte */ 2065 Tracevv((stderr,"%c", s->window[s->strstart])); 2066 _tr_tally_lit(s, s->window[s->strstart], bflush); 2067 s->lookahead--; 2068 s->strstart++; 2069 } 2070 if (bflush) FLUSH_BLOCK(s, 0); 2071 } 2072 s->insert = 0; 2073 if (flush == Z_FINISH) { 2074 FLUSH_BLOCK(s, 1); 2075 return finish_done; 2076 } 2077 if (s->sym_next) 2078 FLUSH_BLOCK(s, 0); 2079 return block_done; 2080 } 2081 2082 /* =========================================================================== 2083 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 2084 * (It will be regenerated if this run of deflate switches away from Huffman.) 2085 */ 2086 local block_state deflate_huff(deflate_state *s, int flush) { 2087 int bflush; /* set if current block must be flushed */ 2088 2089 for (;;) { 2090 /* Make sure that we have a literal to write. */ 2091 if (s->lookahead == 0) { 2092 fill_window(s); 2093 if (s->lookahead == 0) { 2094 if (flush == Z_NO_FLUSH) 2095 return need_more; 2096 break; /* flush the current block */ 2097 } 2098 } 2099 2100 /* Output a literal byte */ 2101 s->match_length = 0; 2102 Tracevv((stderr,"%c", s->window[s->strstart])); 2103 _tr_tally_lit(s, s->window[s->strstart], bflush); 2104 s->lookahead--; 2105 s->strstart++; 2106 if (bflush) FLUSH_BLOCK(s, 0); 2107 } 2108 s->insert = 0; 2109 if (flush == Z_FINISH) { 2110 FLUSH_BLOCK(s, 1); 2111 return finish_done; 2112 } 2113 if (s->sym_next) 2114 FLUSH_BLOCK(s, 0); 2115 return block_done; 2116 } 2117