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 #include "deflate.h" 51 52 /* 53 If you use the zlib library in a product, an acknowledgment is welcome 54 in the documentation of your product. If for some reason you cannot 55 include such an acknowledgment, I would appreciate that you keep this 56 copyright string in the executable of your product. 57 */ 58 59 typedef enum { 60 need_more, /* block not completed, need more input or more output */ 61 block_done, /* block flush performed */ 62 finish_started, /* finish started, need only more output at next deflate */ 63 finish_done /* finish done, accept no more input or output */ 64 } block_state; 65 66 typedef block_state (*compress_func)(deflate_state *s, int flush); 67 /* Compression function. Returns the block state after the call. */ 68 69 local block_state deflate_stored(deflate_state *s, int flush); 70 local block_state deflate_fast(deflate_state *s, int flush); 71 #ifndef FASTEST 72 local block_state deflate_slow(deflate_state *s, int flush); 73 #endif 74 local block_state deflate_rle(deflate_state *s, int flush); 75 local block_state deflate_huff(deflate_state *s, int flush); 76 77 /* =========================================================================== 78 * Local data 79 */ 80 81 #define NIL 0 82 /* Tail of hash chains */ 83 84 #ifndef TOO_FAR 85 # define TOO_FAR 4096 86 #endif 87 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ 88 89 /* Values for max_lazy_match, good_match and max_chain_length, depending on 90 * the desired pack level (0..9). The values given below have been tuned to 91 * exclude worst case performance for pathological files. Better values may be 92 * found for specific files. 93 */ 94 typedef struct config_s { 95 ush good_length; /* reduce lazy search above this match length */ 96 ush max_lazy; /* do not perform lazy search above this match length */ 97 ush nice_length; /* quit search above this match length */ 98 ush max_chain; 99 compress_func func; 100 } config; 101 102 #ifdef FASTEST 103 local const config configuration_table[2] = { 104 /* good lazy nice chain */ 105 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 106 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ 107 #else 108 local const config configuration_table[10] = { 109 /* good lazy nice chain */ 110 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 111 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ 112 /* 2 */ {4, 5, 16, 8, deflate_fast}, 113 /* 3 */ {4, 6, 32, 32, deflate_fast}, 114 115 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ 116 /* 5 */ {8, 16, 32, 32, deflate_slow}, 117 /* 6 */ {8, 16, 128, 128, deflate_slow}, 118 /* 7 */ {8, 32, 128, 256, deflate_slow}, 119 /* 8 */ {32, 128, 258, 1024, deflate_slow}, 120 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ 121 #endif 122 123 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 124 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different 125 * meaning. 126 */ 127 128 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */ 129 #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0)) 130 131 /* =========================================================================== 132 * Update a hash value with the given input byte 133 * IN assertion: all calls to UPDATE_HASH are made with consecutive input 134 * characters, so that a running hash key can be computed from the previous 135 * key instead of complete recalculation each time. 136 */ 137 #define UPDATE_HASH(s,h,c) (h = (((h) << s->hash_shift) ^ (c)) & s->hash_mask) 138 139 140 /* =========================================================================== 141 * Insert string str in the dictionary and set match_head to the previous head 142 * of the hash chain (the most recent string with same hash key). Return 143 * the previous length of the hash chain. 144 * If this file is compiled with -DFASTEST, the compression level is forced 145 * to 1, and no hash chains are maintained. 146 * IN assertion: all calls to INSERT_STRING are made with consecutive input 147 * characters and the first MIN_MATCH bytes of str are valid (except for 148 * the last MIN_MATCH-1 bytes of the input file). 149 */ 150 #ifdef FASTEST 151 #define INSERT_STRING(s, str, match_head) \ 152 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 153 match_head = s->head[s->ins_h], \ 154 s->head[s->ins_h] = (Pos)(str)) 155 #else 156 #define INSERT_STRING(s, str, match_head) \ 157 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 158 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ 159 s->head[s->ins_h] = (Pos)(str)) 160 #endif 161 162 /* =========================================================================== 163 * Initialize the hash table (avoiding 64K overflow for 16 bit systems). 164 * prev[] will be initialized on the fly. 165 */ 166 #define CLEAR_HASH(s) \ 167 do { \ 168 s->head[s->hash_size - 1] = NIL; \ 169 zmemzero((Bytef *)s->head, \ 170 (unsigned)(s->hash_size - 1)*sizeof(*s->head)); \ 171 } while (0) 172 173 /* =========================================================================== 174 * Slide the hash table when sliding the window down (could be avoided with 32 175 * bit values at the expense of memory usage). We slide even when level == 0 to 176 * keep the hash table consistent if we switch back to level > 0 later. 177 */ 178 #if defined(__has_feature) 179 # if __has_feature(memory_sanitizer) 180 __attribute__((no_sanitize("memory"))) 181 # endif 182 #endif 183 local void slide_hash(deflate_state *s) { 184 unsigned n, m; 185 Posf *p; 186 uInt wsize = s->w_size; 187 188 n = s->hash_size; 189 p = &s->head[n]; 190 do { 191 m = *--p; 192 *p = (Pos)(m >= wsize ? m - wsize : NIL); 193 } while (--n); 194 n = wsize; 195 #ifndef FASTEST 196 p = &s->prev[n]; 197 do { 198 m = *--p; 199 *p = (Pos)(m >= wsize ? m - wsize : NIL); 200 /* If n is not on any hash chain, prev[n] is garbage but 201 * its value will never be used. 202 */ 203 } while (--n); 204 #endif 205 } 206 207 /* =========================================================================== 208 * Read a new buffer from the current input stream, update the adler32 209 * and total number of bytes read. All deflate() input goes through 210 * this function so some applications may wish to modify it to avoid 211 * allocating a large strm->next_in buffer and copying from it. 212 * (See also flush_pending()). 213 */ 214 local unsigned read_buf(z_streamp strm, Bytef *buf, unsigned size) { 215 unsigned len = strm->avail_in; 216 217 if (len > size) len = size; 218 if (len == 0) return 0; 219 220 strm->avail_in -= len; 221 222 zmemcpy(buf, strm->next_in, len); 223 if (strm->state->wrap == 1) { 224 strm->adler = adler32(strm->adler, buf, len); 225 } 226 #ifdef GZIP 227 else if (strm->state->wrap == 2) { 228 strm->adler = crc32(strm->adler, buf, len); 229 } 230 #endif 231 strm->next_in += len; 232 strm->total_in += len; 233 234 return len; 235 } 236 237 /* =========================================================================== 238 * Fill the window when the lookahead becomes insufficient. 239 * Updates strstart and lookahead. 240 * 241 * IN assertion: lookahead < MIN_LOOKAHEAD 242 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 243 * At least one byte has been read, or avail_in == 0; reads are 244 * performed for at least two bytes (required for the zip translate_eol 245 * option -- not supported here). 246 */ 247 local void fill_window(deflate_state *s) { 248 unsigned n; 249 unsigned more; /* Amount of free space at the end of the window. */ 250 uInt wsize = s->w_size; 251 252 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); 253 254 do { 255 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 256 257 /* Deal with !@#$% 64K limit: */ 258 if (sizeof(int) <= 2) { 259 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 260 more = wsize; 261 262 } else if (more == (unsigned)(-1)) { 263 /* Very unlikely, but possible on 16 bit machine if 264 * strstart == 0 && lookahead == 1 (input done a byte at time) 265 */ 266 more--; 267 } 268 } 269 270 /* If the window is almost full and there is insufficient lookahead, 271 * move the upper half to the lower one to make room in the upper half. 272 */ 273 if (s->strstart >= wsize + MAX_DIST(s)) { 274 275 zmemcpy(s->window, s->window + wsize, (unsigned)wsize - more); 276 s->match_start -= wsize; 277 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 278 s->block_start -= (long) wsize; 279 if (s->insert > s->strstart) 280 s->insert = s->strstart; 281 slide_hash(s); 282 more += wsize; 283 } 284 if (s->strm->avail_in == 0) break; 285 286 /* If there was no sliding: 287 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 288 * more == window_size - lookahead - strstart 289 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 290 * => more >= window_size - 2*WSIZE + 2 291 * In the BIG_MEM or MMAP case (not yet supported), 292 * window_size == input_size + MIN_LOOKAHEAD && 293 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 294 * Otherwise, window_size == 2*WSIZE so more >= 2. 295 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 296 */ 297 Assert(more >= 2, "more < 2"); 298 299 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 300 s->lookahead += n; 301 302 /* Initialize the hash value now that we have some input: */ 303 if (s->lookahead + s->insert >= MIN_MATCH) { 304 uInt str = s->strstart - s->insert; 305 s->ins_h = s->window[str]; 306 UPDATE_HASH(s, s->ins_h, s->window[str + 1]); 307 #if MIN_MATCH != 3 308 Call UPDATE_HASH() MIN_MATCH-3 more times 309 #endif 310 while (s->insert) { 311 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 312 #ifndef FASTEST 313 s->prev[str & s->w_mask] = s->head[s->ins_h]; 314 #endif 315 s->head[s->ins_h] = (Pos)str; 316 str++; 317 s->insert--; 318 if (s->lookahead + s->insert < MIN_MATCH) 319 break; 320 } 321 } 322 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 323 * but this is not important since only literal bytes will be emitted. 324 */ 325 326 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 327 328 /* If the WIN_INIT bytes after the end of the current data have never been 329 * written, then zero those bytes in order to avoid memory check reports of 330 * the use of uninitialized (or uninitialised as Julian writes) bytes by 331 * the longest match routines. Update the high water mark for the next 332 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 333 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 334 */ 335 if (s->high_water < s->window_size) { 336 ulg curr = s->strstart + (ulg)(s->lookahead); 337 ulg init; 338 339 if (s->high_water < curr) { 340 /* Previous high water mark below current data -- zero WIN_INIT 341 * bytes or up to end of window, whichever is less. 342 */ 343 init = s->window_size - curr; 344 if (init > WIN_INIT) 345 init = WIN_INIT; 346 zmemzero(s->window + curr, (unsigned)init); 347 s->high_water = curr + init; 348 } 349 else if (s->high_water < (ulg)curr + WIN_INIT) { 350 /* High water mark at or above current data, but below current data 351 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 352 * to end of window, whichever is less. 353 */ 354 init = (ulg)curr + WIN_INIT - s->high_water; 355 if (init > s->window_size - s->high_water) 356 init = s->window_size - s->high_water; 357 zmemzero(s->window + s->high_water, (unsigned)init); 358 s->high_water += init; 359 } 360 } 361 362 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 363 "not enough room for search"); 364 } 365 366 /* ========================================================================= */ 367 int ZEXPORT deflateInit_(z_streamp strm, int level, const char *version, 368 int stream_size) { 369 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, 370 Z_DEFAULT_STRATEGY, version, stream_size); 371 /* To do: ignore strm->next_in if we use it as window */ 372 } 373 374 /* ========================================================================= */ 375 int ZEXPORT deflateInit2_(z_streamp strm, int level, int method, 376 int windowBits, int memLevel, int strategy, 377 const char *version, int stream_size) { 378 deflate_state *s; 379 int wrap = 1; 380 static const char my_version[] = ZLIB_VERSION; 381 382 if (version == Z_NULL || version[0] != my_version[0] || 383 stream_size != sizeof(z_stream)) { 384 return Z_VERSION_ERROR; 385 } 386 if (strm == Z_NULL) return Z_STREAM_ERROR; 387 388 strm->msg = Z_NULL; 389 if (strm->zalloc == (alloc_func)0) { 390 #ifdef Z_SOLO 391 return Z_STREAM_ERROR; 392 #else 393 strm->zalloc = zcalloc; 394 strm->opaque = (voidpf)0; 395 #endif 396 } 397 if (strm->zfree == (free_func)0) 398 #ifdef Z_SOLO 399 return Z_STREAM_ERROR; 400 #else 401 strm->zfree = zcfree; 402 #endif 403 404 #ifdef FASTEST 405 if (level != 0) level = 1; 406 #else 407 if (level == Z_DEFAULT_COMPRESSION) level = 6; 408 #endif 409 410 if (windowBits < 0) { /* suppress zlib wrapper */ 411 wrap = 0; 412 if (windowBits < -15) 413 return Z_STREAM_ERROR; 414 windowBits = -windowBits; 415 } 416 #ifdef GZIP 417 else if (windowBits > 15) { 418 wrap = 2; /* write gzip wrapper instead */ 419 windowBits -= 16; 420 } 421 #endif 422 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 423 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 424 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) { 425 return Z_STREAM_ERROR; 426 } 427 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 428 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 429 if (s == Z_NULL) return Z_MEM_ERROR; 430 strm->state = (struct internal_state FAR *)s; 431 s->strm = strm; 432 s->status = INIT_STATE; /* to pass state test in deflateReset() */ 433 434 s->wrap = wrap; 435 s->gzhead = Z_NULL; 436 s->w_bits = (uInt)windowBits; 437 s->w_size = 1 << s->w_bits; 438 s->w_mask = s->w_size - 1; 439 440 s->hash_bits = (uInt)memLevel + 7; 441 s->hash_size = 1 << s->hash_bits; 442 s->hash_mask = s->hash_size - 1; 443 s->hash_shift = ((s->hash_bits + MIN_MATCH-1) / MIN_MATCH); 444 445 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 446 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 447 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 448 449 s->high_water = 0; /* nothing written to s->window yet */ 450 451 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 452 453 /* We overlay pending_buf and sym_buf. This works since the average size 454 * for length/distance pairs over any compressed block is assured to be 31 455 * bits or less. 456 * 457 * Analysis: The longest fixed codes are a length code of 8 bits plus 5 458 * extra bits, for lengths 131 to 257. The longest fixed distance codes are 459 * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest 460 * possible fixed-codes length/distance pair is then 31 bits total. 461 * 462 * sym_buf starts one-fourth of the way into pending_buf. So there are 463 * three bytes in sym_buf for every four bytes in pending_buf. Each symbol 464 * in sym_buf is three bytes -- two for the distance and one for the 465 * literal/length. As each symbol is consumed, the pointer to the next 466 * sym_buf value to read moves forward three bytes. From that symbol, up to 467 * 31 bits are written to pending_buf. The closest the written pending_buf 468 * bits gets to the next sym_buf symbol to read is just before the last 469 * code is written. At that time, 31*(n - 2) bits have been written, just 470 * after 24*(n - 2) bits have been consumed from sym_buf. sym_buf starts at 471 * 8*n bits into pending_buf. (Note that the symbol buffer fills when n - 1 472 * symbols are written.) The closest the writing gets to what is unread is 473 * then n + 14 bits. Here n is lit_bufsize, which is 16384 by default, and 474 * can range from 128 to 32768. 475 * 476 * Therefore, at a minimum, there are 142 bits of space between what is 477 * written and what is read in the overlain buffers, so the symbols cannot 478 * be overwritten by the compressed data. That space is actually 139 bits, 479 * due to the three-bit fixed-code block header. 480 * 481 * That covers the case where either Z_FIXED is specified, forcing fixed 482 * codes, or when the use of fixed codes is chosen, because that choice 483 * results in a smaller compressed block than dynamic codes. That latter 484 * condition then assures that the above analysis also covers all dynamic 485 * blocks. A dynamic-code block will only be chosen to be emitted if it has 486 * fewer bits than a fixed-code block would for the same set of symbols. 487 * Therefore its average symbol length is assured to be less than 31. So 488 * the compressed data for a dynamic block also cannot overwrite the 489 * symbols from which it is being constructed. 490 */ 491 492 s->pending_buf = (uchf *) ZALLOC(strm, s->lit_bufsize, 4); 493 s->pending_buf_size = (ulg)s->lit_bufsize * 4; 494 495 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 496 s->pending_buf == Z_NULL) { 497 s->status = FINISH_STATE; 498 strm->msg = ERR_MSG(Z_MEM_ERROR); 499 deflateEnd (strm); 500 return Z_MEM_ERROR; 501 } 502 s->sym_buf = s->pending_buf + s->lit_bufsize; 503 s->sym_end = (s->lit_bufsize - 1) * 3; 504 /* We avoid equality with lit_bufsize*3 because of wraparound at 64K 505 * on 16 bit machines and because stored blocks are restricted to 506 * 64K-1 bytes. 507 */ 508 509 s->level = level; 510 s->strategy = strategy; 511 s->method = (Byte)method; 512 513 return deflateReset(strm); 514 } 515 516 /* ========================================================================= 517 * Check for a valid deflate stream state. Return 0 if ok, 1 if not. 518 */ 519 local int deflateStateCheck(z_streamp strm) { 520 deflate_state *s; 521 if (strm == Z_NULL || 522 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) 523 return 1; 524 s = strm->state; 525 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE && 526 #ifdef GZIP 527 s->status != GZIP_STATE && 528 #endif 529 s->status != EXTRA_STATE && 530 s->status != NAME_STATE && 531 s->status != COMMENT_STATE && 532 s->status != HCRC_STATE && 533 s->status != BUSY_STATE && 534 s->status != FINISH_STATE)) 535 return 1; 536 return 0; 537 } 538 539 /* ========================================================================= */ 540 int ZEXPORT deflateSetDictionary(z_streamp strm, const Bytef *dictionary, 541 uInt dictLength) { 542 deflate_state *s; 543 uInt str, n; 544 int wrap; 545 unsigned avail; 546 z_const unsigned char *next; 547 548 if (deflateStateCheck(strm) || dictionary == Z_NULL) 549 return Z_STREAM_ERROR; 550 s = strm->state; 551 wrap = s->wrap; 552 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) 553 return Z_STREAM_ERROR; 554 555 /* when using zlib wrappers, compute Adler-32 for provided dictionary */ 556 if (wrap == 1) 557 strm->adler = adler32(strm->adler, dictionary, dictLength); 558 s->wrap = 0; /* avoid computing Adler-32 in read_buf */ 559 560 /* if dictionary would fill window, just replace the history */ 561 if (dictLength >= s->w_size) { 562 if (wrap == 0) { /* already empty otherwise */ 563 CLEAR_HASH(s); 564 s->strstart = 0; 565 s->block_start = 0L; 566 s->insert = 0; 567 } 568 dictionary += dictLength - s->w_size; /* use the tail */ 569 dictLength = s->w_size; 570 } 571 572 /* insert dictionary into window and hash */ 573 avail = strm->avail_in; 574 next = strm->next_in; 575 strm->avail_in = dictLength; 576 strm->next_in = (z_const Bytef *)dictionary; 577 fill_window(s); 578 while (s->lookahead >= MIN_MATCH) { 579 str = s->strstart; 580 n = s->lookahead - (MIN_MATCH-1); 581 do { 582 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 583 #ifndef FASTEST 584 s->prev[str & s->w_mask] = s->head[s->ins_h]; 585 #endif 586 s->head[s->ins_h] = (Pos)str; 587 str++; 588 } while (--n); 589 s->strstart = str; 590 s->lookahead = MIN_MATCH-1; 591 fill_window(s); 592 } 593 s->strstart += s->lookahead; 594 s->block_start = (long)s->strstart; 595 s->insert = s->lookahead; 596 s->lookahead = 0; 597 s->match_length = s->prev_length = MIN_MATCH-1; 598 s->match_available = 0; 599 strm->next_in = next; 600 strm->avail_in = avail; 601 s->wrap = wrap; 602 return Z_OK; 603 } 604 605 /* ========================================================================= */ 606 int ZEXPORT deflateGetDictionary(z_streamp strm, Bytef *dictionary, 607 uInt *dictLength) { 608 deflate_state *s; 609 uInt len; 610 611 if (deflateStateCheck(strm)) 612 return Z_STREAM_ERROR; 613 s = strm->state; 614 len = s->strstart + s->lookahead; 615 if (len > s->w_size) 616 len = s->w_size; 617 if (dictionary != Z_NULL && len) 618 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len); 619 if (dictLength != Z_NULL) 620 *dictLength = len; 621 return Z_OK; 622 } 623 624 /* ========================================================================= */ 625 int ZEXPORT deflateResetKeep(z_streamp strm) { 626 deflate_state *s; 627 628 if (deflateStateCheck(strm)) { 629 return Z_STREAM_ERROR; 630 } 631 632 strm->total_in = strm->total_out = 0; 633 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 634 strm->data_type = Z_UNKNOWN; 635 636 s = (deflate_state *)strm->state; 637 s->pending = 0; 638 s->pending_out = s->pending_buf; 639 640 if (s->wrap < 0) { 641 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 642 } 643 s->status = 644 #ifdef GZIP 645 s->wrap == 2 ? GZIP_STATE : 646 #endif 647 INIT_STATE; 648 strm->adler = 649 #ifdef GZIP 650 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 651 #endif 652 adler32(0L, Z_NULL, 0); 653 s->last_flush = -2; 654 655 _tr_init(s); 656 657 return Z_OK; 658 } 659 660 /* =========================================================================== 661 * Initialize the "longest match" routines for a new zlib stream 662 */ 663 local void lm_init(deflate_state *s) { 664 s->window_size = (ulg)2L*s->w_size; 665 666 CLEAR_HASH(s); 667 668 /* Set the default configuration parameters: 669 */ 670 s->max_lazy_match = configuration_table[s->level].max_lazy; 671 s->good_match = configuration_table[s->level].good_length; 672 s->nice_match = configuration_table[s->level].nice_length; 673 s->max_chain_length = configuration_table[s->level].max_chain; 674 675 s->strstart = 0; 676 s->block_start = 0L; 677 s->lookahead = 0; 678 s->insert = 0; 679 s->match_length = s->prev_length = MIN_MATCH-1; 680 s->match_available = 0; 681 s->ins_h = 0; 682 } 683 684 /* ========================================================================= */ 685 int ZEXPORT deflateReset(z_streamp strm) { 686 int ret; 687 688 ret = deflateResetKeep(strm); 689 if (ret == Z_OK) 690 lm_init(strm->state); 691 return ret; 692 } 693 694 /* ========================================================================= */ 695 int ZEXPORT deflateSetHeader(z_streamp strm, gz_headerp head) { 696 if (deflateStateCheck(strm) || strm->state->wrap != 2) 697 return Z_STREAM_ERROR; 698 strm->state->gzhead = head; 699 return Z_OK; 700 } 701 702 /* ========================================================================= */ 703 int ZEXPORT deflatePending(z_streamp strm, unsigned *pending, int *bits) { 704 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 705 if (pending != Z_NULL) 706 *pending = strm->state->pending; 707 if (bits != Z_NULL) 708 *bits = strm->state->bi_valid; 709 return Z_OK; 710 } 711 712 /* ========================================================================= */ 713 int ZEXPORT deflatePrime(z_streamp strm, int bits, int value) { 714 deflate_state *s; 715 int put; 716 717 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 718 s = strm->state; 719 if (bits < 0 || bits > 16 || 720 s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3)) 721 return Z_BUF_ERROR; 722 do { 723 put = Buf_size - s->bi_valid; 724 if (put > bits) 725 put = bits; 726 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); 727 s->bi_valid += put; 728 _tr_flush_bits(s); 729 value >>= put; 730 bits -= put; 731 } while (bits); 732 return Z_OK; 733 } 734 735 /* ========================================================================= */ 736 int ZEXPORT deflateParams(z_streamp strm, int level, int strategy) { 737 deflate_state *s; 738 compress_func func; 739 740 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 741 s = strm->state; 742 743 #ifdef FASTEST 744 if (level != 0) level = 1; 745 #else 746 if (level == Z_DEFAULT_COMPRESSION) level = 6; 747 #endif 748 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 749 return Z_STREAM_ERROR; 750 } 751 func = configuration_table[s->level].func; 752 753 if ((strategy != s->strategy || func != configuration_table[level].func) && 754 s->last_flush != -2) { 755 /* Flush the last buffer: */ 756 int err = deflate(strm, Z_BLOCK); 757 if (err == Z_STREAM_ERROR) 758 return err; 759 if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead) 760 return Z_BUF_ERROR; 761 } 762 if (s->level != level) { 763 if (s->level == 0 && s->matches != 0) { 764 if (s->matches == 1) 765 slide_hash(s); 766 else 767 CLEAR_HASH(s); 768 s->matches = 0; 769 } 770 s->level = level; 771 s->max_lazy_match = configuration_table[level].max_lazy; 772 s->good_match = configuration_table[level].good_length; 773 s->nice_match = configuration_table[level].nice_length; 774 s->max_chain_length = configuration_table[level].max_chain; 775 } 776 s->strategy = strategy; 777 return Z_OK; 778 } 779 780 /* ========================================================================= */ 781 int ZEXPORT deflateTune(z_streamp strm, int good_length, int max_lazy, 782 int nice_length, int max_chain) { 783 deflate_state *s; 784 785 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 786 s = strm->state; 787 s->good_match = (uInt)good_length; 788 s->max_lazy_match = (uInt)max_lazy; 789 s->nice_match = nice_length; 790 s->max_chain_length = (uInt)max_chain; 791 return Z_OK; 792 } 793 794 /* ========================================================================= 795 * For the default windowBits of 15 and memLevel of 8, this function returns a 796 * close to exact, as well as small, upper bound on the compressed size. This 797 * is an expansion of ~0.03%, plus a small constant. 798 * 799 * For any setting other than those defaults for windowBits and memLevel, one 800 * of two worst case bounds is returned. This is at most an expansion of ~4% or 801 * ~13%, plus a small constant. 802 * 803 * Both the 0.03% and 4% derive from the overhead of stored blocks. The first 804 * one is for stored blocks of 16383 bytes (memLevel == 8), whereas the second 805 * is for stored blocks of 127 bytes (the worst case memLevel == 1). The 806 * expansion results from five bytes of header for each stored block. 807 * 808 * The larger expansion of 13% results from a window size less than or equal to 809 * the symbols buffer size (windowBits <= memLevel + 7). In that case some of 810 * the data being compressed may have slid out of the sliding window, impeding 811 * a stored block from being emitted. Then the only choice is a fixed or 812 * dynamic block, where a fixed block limits the maximum expansion to 9 bits 813 * per 8-bit byte, plus 10 bits for every block. The smallest block size for 814 * which this can occur is 255 (memLevel == 2). 815 * 816 * Shifts are used to approximate divisions, for speed. 817 */ 818 uLong ZEXPORT deflateBound(z_streamp strm, uLong sourceLen) { 819 deflate_state *s; 820 uLong fixedlen, storelen, wraplen; 821 822 /* upper bound for fixed blocks with 9-bit literals and length 255 823 (memLevel == 2, which is the lowest that may not use stored blocks) -- 824 ~13% overhead plus a small constant */ 825 fixedlen = sourceLen + (sourceLen >> 3) + (sourceLen >> 8) + 826 (sourceLen >> 9) + 4; 827 828 /* upper bound for stored blocks with length 127 (memLevel == 1) -- 829 ~4% overhead plus a small constant */ 830 storelen = sourceLen + (sourceLen >> 5) + (sourceLen >> 7) + 831 (sourceLen >> 11) + 7; 832 833 /* if can't get parameters, return larger bound plus a zlib wrapper */ 834 if (deflateStateCheck(strm)) 835 return (fixedlen > storelen ? fixedlen : storelen) + 6; 836 837 /* compute wrapper length */ 838 s = strm->state; 839 switch (s->wrap) { 840 case 0: /* raw deflate */ 841 wraplen = 0; 842 break; 843 case 1: /* zlib wrapper */ 844 wraplen = 6 + (s->strstart ? 4 : 0); 845 break; 846 #ifdef GZIP 847 case 2: /* gzip wrapper */ 848 wraplen = 18; 849 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 850 Bytef *str; 851 if (s->gzhead->extra != Z_NULL) 852 wraplen += 2 + s->gzhead->extra_len; 853 str = s->gzhead->name; 854 if (str != Z_NULL) 855 do { 856 wraplen++; 857 } while (*str++); 858 str = s->gzhead->comment; 859 if (str != Z_NULL) 860 do { 861 wraplen++; 862 } while (*str++); 863 if (s->gzhead->hcrc) 864 wraplen += 2; 865 } 866 break; 867 #endif 868 default: /* for compiler happiness */ 869 wraplen = 6; 870 } 871 872 /* if not default parameters, return one of the conservative bounds */ 873 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 874 return (s->w_bits <= s->hash_bits && s->level ? fixedlen : storelen) + 875 wraplen; 876 877 /* default settings: return tight bound for that case -- ~0.03% overhead 878 plus a small constant */ 879 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 880 (sourceLen >> 25) + 13 - 6 + wraplen; 881 } 882 883 /* ========================================================================= 884 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 885 * IN assertion: the stream state is correct and there is enough room in 886 * pending_buf. 887 */ 888 local void putShortMSB(deflate_state *s, uInt b) { 889 put_byte(s, (Byte)(b >> 8)); 890 put_byte(s, (Byte)(b & 0xff)); 891 } 892 893 /* ========================================================================= 894 * Flush as much pending output as possible. All deflate() output, except for 895 * some deflate_stored() output, goes through this function so some 896 * applications may wish to modify it to avoid allocating a large 897 * strm->next_out buffer and copying into it. (See also read_buf()). 898 */ 899 local void flush_pending(z_streamp strm) { 900 unsigned len; 901 deflate_state *s = strm->state; 902 903 _tr_flush_bits(s); 904 len = s->pending; 905 if (len > strm->avail_out) len = strm->avail_out; 906 if (len == 0) return; 907 908 zmemcpy(strm->next_out, s->pending_out, len); 909 strm->next_out += len; 910 s->pending_out += len; 911 strm->total_out += len; 912 strm->avail_out -= len; 913 s->pending -= len; 914 if (s->pending == 0) { 915 s->pending_out = s->pending_buf; 916 } 917 } 918 919 /* =========================================================================== 920 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1]. 921 */ 922 #define HCRC_UPDATE(beg) \ 923 do { \ 924 if (s->gzhead->hcrc && s->pending > (beg)) \ 925 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \ 926 s->pending - (beg)); \ 927 } while (0) 928 929 /* ========================================================================= */ 930 int ZEXPORT deflate(z_streamp strm, int flush) { 931 int old_flush; /* value of flush param for previous deflate call */ 932 deflate_state *s; 933 934 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { 935 return Z_STREAM_ERROR; 936 } 937 s = strm->state; 938 939 if (strm->next_out == Z_NULL || 940 (strm->avail_in != 0 && strm->next_in == Z_NULL) || 941 (s->status == FINISH_STATE && flush != Z_FINISH)) { 942 ERR_RETURN(strm, Z_STREAM_ERROR); 943 } 944 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 945 946 old_flush = s->last_flush; 947 s->last_flush = flush; 948 949 /* Flush as much pending output as possible */ 950 if (s->pending != 0) { 951 flush_pending(strm); 952 if (strm->avail_out == 0) { 953 /* Since avail_out is 0, deflate will be called again with 954 * more output space, but possibly with both pending and 955 * avail_in equal to zero. There won't be anything to do, 956 * but this is not an error situation so make sure we 957 * return OK instead of BUF_ERROR at next call of deflate: 958 */ 959 s->last_flush = -1; 960 return Z_OK; 961 } 962 963 /* Make sure there is something to do and avoid duplicate consecutive 964 * flushes. For repeated and useless calls with Z_FINISH, we keep 965 * returning Z_STREAM_END instead of Z_BUF_ERROR. 966 */ 967 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 968 flush != Z_FINISH) { 969 ERR_RETURN(strm, Z_BUF_ERROR); 970 } 971 972 /* User must not provide more input after the first FINISH: */ 973 if (s->status == FINISH_STATE && strm->avail_in != 0) { 974 ERR_RETURN(strm, Z_BUF_ERROR); 975 } 976 977 /* Write the header */ 978 if (s->status == INIT_STATE && s->wrap == 0) 979 s->status = BUSY_STATE; 980 if (s->status == INIT_STATE) { 981 /* zlib header */ 982 uInt header = (Z_DEFLATED + ((s->w_bits - 8) << 4)) << 8; 983 uInt level_flags; 984 985 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 986 level_flags = 0; 987 else if (s->level < 6) 988 level_flags = 1; 989 else if (s->level == 6) 990 level_flags = 2; 991 else 992 level_flags = 3; 993 header |= (level_flags << 6); 994 if (s->strstart != 0) header |= PRESET_DICT; 995 header += 31 - (header % 31); 996 997 putShortMSB(s, header); 998 999 /* Save the adler32 of the preset dictionary: */ 1000 if (s->strstart != 0) { 1001 putShortMSB(s, (uInt)(strm->adler >> 16)); 1002 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1003 } 1004 strm->adler = adler32(0L, Z_NULL, 0); 1005 s->status = BUSY_STATE; 1006 1007 /* Compression must start with an empty pending buffer */ 1008 flush_pending(strm); 1009 if (s->pending != 0) { 1010 s->last_flush = -1; 1011 return Z_OK; 1012 } 1013 } 1014 #ifdef GZIP 1015 if (s->status == GZIP_STATE) { 1016 /* gzip header */ 1017 strm->adler = crc32(0L, Z_NULL, 0); 1018 put_byte(s, 31); 1019 put_byte(s, 139); 1020 put_byte(s, 8); 1021 if (s->gzhead == Z_NULL) { 1022 put_byte(s, 0); 1023 put_byte(s, 0); 1024 put_byte(s, 0); 1025 put_byte(s, 0); 1026 put_byte(s, 0); 1027 put_byte(s, s->level == 9 ? 2 : 1028 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 1029 4 : 0)); 1030 put_byte(s, OS_CODE); 1031 s->status = BUSY_STATE; 1032 1033 /* Compression must start with an empty pending buffer */ 1034 flush_pending(strm); 1035 if (s->pending != 0) { 1036 s->last_flush = -1; 1037 return Z_OK; 1038 } 1039 } 1040 else { 1041 put_byte(s, (s->gzhead->text ? 1 : 0) + 1042 (s->gzhead->hcrc ? 2 : 0) + 1043 (s->gzhead->extra == Z_NULL ? 0 : 4) + 1044 (s->gzhead->name == Z_NULL ? 0 : 8) + 1045 (s->gzhead->comment == Z_NULL ? 0 : 16) 1046 ); 1047 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 1048 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 1049 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 1050 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 1051 put_byte(s, s->level == 9 ? 2 : 1052 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 1053 4 : 0)); 1054 put_byte(s, s->gzhead->os & 0xff); 1055 if (s->gzhead->extra != Z_NULL) { 1056 put_byte(s, s->gzhead->extra_len & 0xff); 1057 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 1058 } 1059 if (s->gzhead->hcrc) 1060 strm->adler = crc32(strm->adler, s->pending_buf, 1061 s->pending); 1062 s->gzindex = 0; 1063 s->status = EXTRA_STATE; 1064 } 1065 } 1066 if (s->status == EXTRA_STATE) { 1067 if (s->gzhead->extra != Z_NULL) { 1068 ulg beg = s->pending; /* start of bytes to update crc */ 1069 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex; 1070 while (s->pending + left > s->pending_buf_size) { 1071 uInt copy = s->pending_buf_size - s->pending; 1072 zmemcpy(s->pending_buf + s->pending, 1073 s->gzhead->extra + s->gzindex, copy); 1074 s->pending = s->pending_buf_size; 1075 HCRC_UPDATE(beg); 1076 s->gzindex += copy; 1077 flush_pending(strm); 1078 if (s->pending != 0) { 1079 s->last_flush = -1; 1080 return Z_OK; 1081 } 1082 beg = 0; 1083 left -= copy; 1084 } 1085 zmemcpy(s->pending_buf + s->pending, 1086 s->gzhead->extra + s->gzindex, left); 1087 s->pending += left; 1088 HCRC_UPDATE(beg); 1089 s->gzindex = 0; 1090 } 1091 s->status = NAME_STATE; 1092 } 1093 if (s->status == NAME_STATE) { 1094 if (s->gzhead->name != Z_NULL) { 1095 ulg beg = s->pending; /* start of bytes to update crc */ 1096 int val; 1097 do { 1098 if (s->pending == s->pending_buf_size) { 1099 HCRC_UPDATE(beg); 1100 flush_pending(strm); 1101 if (s->pending != 0) { 1102 s->last_flush = -1; 1103 return Z_OK; 1104 } 1105 beg = 0; 1106 } 1107 val = s->gzhead->name[s->gzindex++]; 1108 put_byte(s, val); 1109 } while (val != 0); 1110 HCRC_UPDATE(beg); 1111 s->gzindex = 0; 1112 } 1113 s->status = COMMENT_STATE; 1114 } 1115 if (s->status == COMMENT_STATE) { 1116 if (s->gzhead->comment != Z_NULL) { 1117 ulg beg = s->pending; /* start of bytes to update crc */ 1118 int val; 1119 do { 1120 if (s->pending == s->pending_buf_size) { 1121 HCRC_UPDATE(beg); 1122 flush_pending(strm); 1123 if (s->pending != 0) { 1124 s->last_flush = -1; 1125 return Z_OK; 1126 } 1127 beg = 0; 1128 } 1129 val = s->gzhead->comment[s->gzindex++]; 1130 put_byte(s, val); 1131 } while (val != 0); 1132 HCRC_UPDATE(beg); 1133 } 1134 s->status = HCRC_STATE; 1135 } 1136 if (s->status == HCRC_STATE) { 1137 if (s->gzhead->hcrc) { 1138 if (s->pending + 2 > s->pending_buf_size) { 1139 flush_pending(strm); 1140 if (s->pending != 0) { 1141 s->last_flush = -1; 1142 return Z_OK; 1143 } 1144 } 1145 put_byte(s, (Byte)(strm->adler & 0xff)); 1146 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1147 strm->adler = crc32(0L, Z_NULL, 0); 1148 } 1149 s->status = BUSY_STATE; 1150 1151 /* Compression must start with an empty pending buffer */ 1152 flush_pending(strm); 1153 if (s->pending != 0) { 1154 s->last_flush = -1; 1155 return Z_OK; 1156 } 1157 } 1158 #endif 1159 1160 /* Start a new block or continue the current one. 1161 */ 1162 if (strm->avail_in != 0 || s->lookahead != 0 || 1163 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 1164 block_state bstate; 1165 1166 bstate = s->level == 0 ? deflate_stored(s, flush) : 1167 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 1168 s->strategy == Z_RLE ? deflate_rle(s, flush) : 1169 (*(configuration_table[s->level].func))(s, flush); 1170 1171 if (bstate == finish_started || bstate == finish_done) { 1172 s->status = FINISH_STATE; 1173 } 1174 if (bstate == need_more || bstate == finish_started) { 1175 if (strm->avail_out == 0) { 1176 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 1177 } 1178 return Z_OK; 1179 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 1180 * of deflate should use the same flush parameter to make sure 1181 * that the flush is complete. So we don't have to output an 1182 * empty block here, this will be done at next call. This also 1183 * ensures that for a very small output buffer, we emit at most 1184 * one empty block. 1185 */ 1186 } 1187 if (bstate == block_done) { 1188 if (flush == Z_PARTIAL_FLUSH) { 1189 _tr_align(s); 1190 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 1191 _tr_stored_block(s, (char*)0, 0L, 0); 1192 /* For a full flush, this empty block will be recognized 1193 * as a special marker by inflate_sync(). 1194 */ 1195 if (flush == Z_FULL_FLUSH) { 1196 CLEAR_HASH(s); /* forget history */ 1197 if (s->lookahead == 0) { 1198 s->strstart = 0; 1199 s->block_start = 0L; 1200 s->insert = 0; 1201 } 1202 } 1203 } 1204 flush_pending(strm); 1205 if (strm->avail_out == 0) { 1206 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 1207 return Z_OK; 1208 } 1209 } 1210 } 1211 1212 if (flush != Z_FINISH) return Z_OK; 1213 if (s->wrap <= 0) return Z_STREAM_END; 1214 1215 /* Write the trailer */ 1216 #ifdef GZIP 1217 if (s->wrap == 2) { 1218 put_byte(s, (Byte)(strm->adler & 0xff)); 1219 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1220 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 1221 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 1222 put_byte(s, (Byte)(strm->total_in & 0xff)); 1223 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 1224 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 1225 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 1226 } 1227 else 1228 #endif 1229 { 1230 putShortMSB(s, (uInt)(strm->adler >> 16)); 1231 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1232 } 1233 flush_pending(strm); 1234 /* If avail_out is zero, the application will call deflate again 1235 * to flush the rest. 1236 */ 1237 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 1238 return s->pending != 0 ? Z_OK : Z_STREAM_END; 1239 } 1240 1241 /* ========================================================================= */ 1242 int ZEXPORT deflateEnd(z_streamp strm) { 1243 int status; 1244 1245 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 1246 1247 status = strm->state->status; 1248 1249 /* Deallocate in reverse order of allocations: */ 1250 TRY_FREE(strm, strm->state->pending_buf); 1251 TRY_FREE(strm, strm->state->head); 1252 TRY_FREE(strm, strm->state->prev); 1253 TRY_FREE(strm, strm->state->window); 1254 1255 ZFREE(strm, strm->state); 1256 strm->state = Z_NULL; 1257 1258 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1259 } 1260 1261 /* ========================================================================= 1262 * Copy the source state to the destination state. 1263 * To simplify the source, this is not supported for 16-bit MSDOS (which 1264 * doesn't have enough memory anyway to duplicate compression states). 1265 */ 1266 int ZEXPORT deflateCopy(z_streamp dest, z_streamp source) { 1267 #ifdef MAXSEG_64K 1268 (void)dest; 1269 (void)source; 1270 return Z_STREAM_ERROR; 1271 #else 1272 deflate_state *ds; 1273 deflate_state *ss; 1274 1275 1276 if (deflateStateCheck(source) || dest == Z_NULL) { 1277 return Z_STREAM_ERROR; 1278 } 1279 1280 ss = source->state; 1281 1282 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream)); 1283 1284 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1285 if (ds == Z_NULL) return Z_MEM_ERROR; 1286 dest->state = (struct internal_state FAR *) ds; 1287 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state)); 1288 ds->strm = dest; 1289 1290 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1291 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1292 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1293 ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, 4); 1294 1295 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1296 ds->pending_buf == Z_NULL) { 1297 deflateEnd (dest); 1298 return Z_MEM_ERROR; 1299 } 1300 /* following zmemcpy do not work for 16-bit MSDOS */ 1301 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1302 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos)); 1303 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos)); 1304 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); 1305 1306 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1307 ds->sym_buf = ds->pending_buf + ds->lit_bufsize; 1308 1309 ds->l_desc.dyn_tree = ds->dyn_ltree; 1310 ds->d_desc.dyn_tree = ds->dyn_dtree; 1311 ds->bl_desc.dyn_tree = ds->bl_tree; 1312 1313 return Z_OK; 1314 #endif /* MAXSEG_64K */ 1315 } 1316 1317 #ifndef FASTEST 1318 /* =========================================================================== 1319 * Set match_start to the longest match starting at the given string and 1320 * return its length. Matches shorter or equal to prev_length are discarded, 1321 * in which case the result is equal to prev_length and match_start is 1322 * garbage. 1323 * IN assertions: cur_match is the head of the hash chain for the current 1324 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1325 * OUT assertion: the match length is not greater than s->lookahead. 1326 */ 1327 local uInt longest_match(deflate_state *s, IPos cur_match) { 1328 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1329 register Bytef *scan = s->window + s->strstart; /* current string */ 1330 register Bytef *match; /* matched string */ 1331 register int len; /* length of current match */ 1332 int best_len = (int)s->prev_length; /* best match length so far */ 1333 int nice_match = s->nice_match; /* stop if match long enough */ 1334 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1335 s->strstart - (IPos)MAX_DIST(s) : NIL; 1336 /* Stop when cur_match becomes <= limit. To simplify the code, 1337 * we prevent matches with the string of window index 0. 1338 */ 1339 Posf *prev = s->prev; 1340 uInt wmask = s->w_mask; 1341 1342 #ifdef UNALIGNED_OK 1343 /* Compare two bytes at a time. Note: this is not always beneficial. 1344 * Try with and without -DUNALIGNED_OK to check. 1345 */ 1346 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1347 register ush scan_start = *(ushf*)scan; 1348 register ush scan_end = *(ushf*)(scan + best_len - 1); 1349 #else 1350 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1351 register Byte scan_end1 = scan[best_len - 1]; 1352 register Byte scan_end = scan[best_len]; 1353 #endif 1354 1355 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1356 * It is easy to get rid of this optimization if necessary. 1357 */ 1358 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1359 1360 /* Do not waste too much time if we already have a good match: */ 1361 if (s->prev_length >= s->good_match) { 1362 chain_length >>= 2; 1363 } 1364 /* Do not look for matches beyond the end of the input. This is necessary 1365 * to make deflate deterministic. 1366 */ 1367 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead; 1368 1369 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1370 "need lookahead"); 1371 1372 do { 1373 Assert(cur_match < s->strstart, "no future"); 1374 match = s->window + cur_match; 1375 1376 /* Skip to next match if the match length cannot increase 1377 * or if the match length is less than 2. Note that the checks below 1378 * for insufficient lookahead only occur occasionally for performance 1379 * reasons. Therefore uninitialized memory will be accessed, and 1380 * conditional jumps will be made that depend on those values. 1381 * However the length of the match is limited to the lookahead, so 1382 * the output of deflate is not affected by the uninitialized values. 1383 */ 1384 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1385 /* This code assumes sizeof(unsigned short) == 2. Do not use 1386 * UNALIGNED_OK if your compiler uses a different size. 1387 */ 1388 if (*(ushf*)(match + best_len - 1) != scan_end || 1389 *(ushf*)match != scan_start) continue; 1390 1391 /* It is not necessary to compare scan[2] and match[2] since they are 1392 * always equal when the other bytes match, given that the hash keys 1393 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1394 * strstart + 3, + 5, up to strstart + 257. We check for insufficient 1395 * lookahead only every 4th comparison; the 128th check will be made 1396 * at strstart + 257. If MAX_MATCH-2 is not a multiple of 8, it is 1397 * necessary to put more guard bytes at the end of the window, or 1398 * to check more often for insufficient lookahead. 1399 */ 1400 Assert(scan[2] == match[2], "scan[2]?"); 1401 scan++, match++; 1402 do { 1403 } while (*(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1404 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1405 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1406 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1407 scan < strend); 1408 /* The funny "do {}" generates better code on most compilers */ 1409 1410 /* Here, scan <= window + strstart + 257 */ 1411 Assert(scan <= s->window + (unsigned)(s->window_size - 1), 1412 "wild scan"); 1413 if (*scan == *match) scan++; 1414 1415 len = (MAX_MATCH - 1) - (int)(strend - scan); 1416 scan = strend - (MAX_MATCH-1); 1417 1418 #else /* UNALIGNED_OK */ 1419 1420 if (match[best_len] != scan_end || 1421 match[best_len - 1] != scan_end1 || 1422 *match != *scan || 1423 *++match != scan[1]) continue; 1424 1425 /* The check at best_len - 1 can be removed because it will be made 1426 * again later. (This heuristic is not always a win.) 1427 * It is not necessary to compare scan[2] and match[2] since they 1428 * are always equal when the other bytes match, given that 1429 * the hash keys are equal and that HASH_BITS >= 8. 1430 */ 1431 scan += 2, match++; 1432 Assert(*scan == *match, "match[2]?"); 1433 1434 /* We check for insufficient lookahead only every 8th comparison; 1435 * the 256th check will be made at strstart + 258. 1436 */ 1437 do { 1438 } while (*++scan == *++match && *++scan == *++match && 1439 *++scan == *++match && *++scan == *++match && 1440 *++scan == *++match && *++scan == *++match && 1441 *++scan == *++match && *++scan == *++match && 1442 scan < strend); 1443 1444 Assert(scan <= s->window + (unsigned)(s->window_size - 1), 1445 "wild scan"); 1446 1447 len = MAX_MATCH - (int)(strend - scan); 1448 scan = strend - MAX_MATCH; 1449 1450 #endif /* UNALIGNED_OK */ 1451 1452 if (len > best_len) { 1453 s->match_start = cur_match; 1454 best_len = len; 1455 if (len >= nice_match) break; 1456 #ifdef UNALIGNED_OK 1457 scan_end = *(ushf*)(scan + best_len - 1); 1458 #else 1459 scan_end1 = scan[best_len - 1]; 1460 scan_end = scan[best_len]; 1461 #endif 1462 } 1463 } while ((cur_match = prev[cur_match & wmask]) > limit 1464 && --chain_length != 0); 1465 1466 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1467 return s->lookahead; 1468 } 1469 1470 #else /* FASTEST */ 1471 1472 /* --------------------------------------------------------------------------- 1473 * Optimized version for FASTEST only 1474 */ 1475 local uInt longest_match(deflate_state *s, IPos cur_match) { 1476 register Bytef *scan = s->window + s->strstart; /* current string */ 1477 register Bytef *match; /* matched string */ 1478 register int len; /* length of current match */ 1479 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1480 1481 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1482 * It is easy to get rid of this optimization if necessary. 1483 */ 1484 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1485 1486 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1487 "need lookahead"); 1488 1489 Assert(cur_match < s->strstart, "no future"); 1490 1491 match = s->window + cur_match; 1492 1493 /* Return failure if the match length is less than 2: 1494 */ 1495 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1496 1497 /* The check at best_len - 1 can be removed because it will be made 1498 * again later. (This heuristic is not always a win.) 1499 * It is not necessary to compare scan[2] and match[2] since they 1500 * are always equal when the other bytes match, given that 1501 * the hash keys are equal and that HASH_BITS >= 8. 1502 */ 1503 scan += 2, match += 2; 1504 Assert(*scan == *match, "match[2]?"); 1505 1506 /* We check for insufficient lookahead only every 8th comparison; 1507 * the 256th check will be made at strstart + 258. 1508 */ 1509 do { 1510 } while (*++scan == *++match && *++scan == *++match && 1511 *++scan == *++match && *++scan == *++match && 1512 *++scan == *++match && *++scan == *++match && 1513 *++scan == *++match && *++scan == *++match && 1514 scan < strend); 1515 1516 Assert(scan <= s->window + (unsigned)(s->window_size - 1), "wild scan"); 1517 1518 len = MAX_MATCH - (int)(strend - scan); 1519 1520 if (len < MIN_MATCH) return MIN_MATCH - 1; 1521 1522 s->match_start = cur_match; 1523 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1524 } 1525 1526 #endif /* FASTEST */ 1527 1528 #ifdef ZLIB_DEBUG 1529 1530 #define EQUAL 0 1531 /* result of memcmp for equal strings */ 1532 1533 /* =========================================================================== 1534 * Check that the match at match_start is indeed a match. 1535 */ 1536 local void check_match(deflate_state *s, IPos start, IPos match, int length) { 1537 /* check that the match is indeed a match */ 1538 if (zmemcmp(s->window + match, 1539 s->window + start, length) != EQUAL) { 1540 fprintf(stderr, " start %u, match %u, length %d\n", 1541 start, match, length); 1542 do { 1543 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); 1544 } while (--length != 0); 1545 z_error("invalid match"); 1546 } 1547 if (z_verbose > 1) { 1548 fprintf(stderr,"\\[%d,%d]", start - match, length); 1549 do { putc(s->window[start++], stderr); } while (--length != 0); 1550 } 1551 } 1552 #else 1553 # define check_match(s, start, match, length) 1554 #endif /* ZLIB_DEBUG */ 1555 1556 /* =========================================================================== 1557 * Flush the current block, with given end-of-file flag. 1558 * IN assertion: strstart is set to the end of the current match. 1559 */ 1560 #define FLUSH_BLOCK_ONLY(s, last) { \ 1561 _tr_flush_block(s, (s->block_start >= 0L ? \ 1562 (charf *)&s->window[(unsigned)s->block_start] : \ 1563 (charf *)Z_NULL), \ 1564 (ulg)((long)s->strstart - s->block_start), \ 1565 (last)); \ 1566 s->block_start = s->strstart; \ 1567 flush_pending(s->strm); \ 1568 Tracev((stderr,"[FLUSH]")); \ 1569 } 1570 1571 /* Same but force premature exit if necessary. */ 1572 #define FLUSH_BLOCK(s, last) { \ 1573 FLUSH_BLOCK_ONLY(s, last); \ 1574 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1575 } 1576 1577 /* Maximum stored block length in deflate format (not including header). */ 1578 #define MAX_STORED 65535 1579 1580 /* Minimum of a and b. */ 1581 #define MIN(a, b) ((a) > (b) ? (b) : (a)) 1582 1583 /* =========================================================================== 1584 * Copy without compression as much as possible from the input stream, return 1585 * the current block state. 1586 * 1587 * In case deflateParams() is used to later switch to a non-zero compression 1588 * level, s->matches (otherwise unused when storing) keeps track of the number 1589 * of hash table slides to perform. If s->matches is 1, then one hash table 1590 * slide will be done when switching. If s->matches is 2, the maximum value 1591 * allowed here, then the hash table will be cleared, since two or more slides 1592 * is the same as a clear. 1593 * 1594 * deflate_stored() is written to minimize the number of times an input byte is 1595 * copied. It is most efficient with large input and output buffers, which 1596 * maximizes the opportunities to have a single copy from next_in to next_out. 1597 */ 1598 local block_state deflate_stored(deflate_state *s, int flush) { 1599 /* Smallest worthy block size when not flushing or finishing. By default 1600 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For 1601 * large input and output buffers, the stored block size will be larger. 1602 */ 1603 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size); 1604 1605 /* Copy as many min_block or larger stored blocks directly to next_out as 1606 * possible. If flushing, copy the remaining available input to next_out as 1607 * stored blocks, if there is enough space. 1608 */ 1609 unsigned len, left, have, last = 0; 1610 unsigned used = s->strm->avail_in; 1611 do { 1612 /* Set len to the maximum size block that we can copy directly with the 1613 * available input data and output space. Set left to how much of that 1614 * would be copied from what's left in the window. 1615 */ 1616 len = MAX_STORED; /* maximum deflate stored block length */ 1617 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1618 if (s->strm->avail_out < have) /* need room for header */ 1619 break; 1620 /* maximum stored block length that will fit in avail_out: */ 1621 have = s->strm->avail_out - have; 1622 left = s->strstart - s->block_start; /* bytes left in window */ 1623 if (len > (ulg)left + s->strm->avail_in) 1624 len = left + s->strm->avail_in; /* limit len to the input */ 1625 if (len > have) 1626 len = have; /* limit len to the output */ 1627 1628 /* If the stored block would be less than min_block in length, or if 1629 * unable to copy all of the available input when flushing, then try 1630 * copying to the window and the pending buffer instead. Also don't 1631 * write an empty block when flushing -- deflate() does that. 1632 */ 1633 if (len < min_block && ((len == 0 && flush != Z_FINISH) || 1634 flush == Z_NO_FLUSH || 1635 len != left + s->strm->avail_in)) 1636 break; 1637 1638 /* Make a dummy stored block in pending to get the header bytes, 1639 * including any pending bits. This also updates the debugging counts. 1640 */ 1641 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0; 1642 _tr_stored_block(s, (char *)0, 0L, last); 1643 1644 /* Replace the lengths in the dummy stored block with len. */ 1645 s->pending_buf[s->pending - 4] = len; 1646 s->pending_buf[s->pending - 3] = len >> 8; 1647 s->pending_buf[s->pending - 2] = ~len; 1648 s->pending_buf[s->pending - 1] = ~len >> 8; 1649 1650 /* Write the stored block header bytes. */ 1651 flush_pending(s->strm); 1652 1653 #ifdef ZLIB_DEBUG 1654 /* Update debugging counts for the data about to be copied. */ 1655 s->compressed_len += len << 3; 1656 s->bits_sent += len << 3; 1657 #endif 1658 1659 /* Copy uncompressed bytes from the window to next_out. */ 1660 if (left) { 1661 if (left > len) 1662 left = len; 1663 zmemcpy(s->strm->next_out, s->window + s->block_start, left); 1664 s->strm->next_out += left; 1665 s->strm->avail_out -= left; 1666 s->strm->total_out += left; 1667 s->block_start += left; 1668 len -= left; 1669 } 1670 1671 /* Copy uncompressed bytes directly from next_in to next_out, updating 1672 * the check value. 1673 */ 1674 if (len) { 1675 read_buf(s->strm, s->strm->next_out, len); 1676 s->strm->next_out += len; 1677 s->strm->avail_out -= len; 1678 s->strm->total_out += len; 1679 } 1680 } while (last == 0); 1681 1682 /* Update the sliding window with the last s->w_size bytes of the copied 1683 * data, or append all of the copied data to the existing window if less 1684 * than s->w_size bytes were copied. Also update the number of bytes to 1685 * insert in the hash tables, in the event that deflateParams() switches to 1686 * a non-zero compression level. 1687 */ 1688 used -= s->strm->avail_in; /* number of input bytes directly copied */ 1689 if (used) { 1690 /* If any input was used, then no unused input remains in the window, 1691 * therefore s->block_start == s->strstart. 1692 */ 1693 if (used >= s->w_size) { /* supplant the previous history */ 1694 s->matches = 2; /* clear hash */ 1695 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size); 1696 s->strstart = s->w_size; 1697 s->insert = s->strstart; 1698 } 1699 else { 1700 if (s->window_size - s->strstart <= used) { 1701 /* Slide the window down. */ 1702 s->strstart -= s->w_size; 1703 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1704 if (s->matches < 2) 1705 s->matches++; /* add a pending slide_hash() */ 1706 if (s->insert > s->strstart) 1707 s->insert = s->strstart; 1708 } 1709 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used); 1710 s->strstart += used; 1711 s->insert += MIN(used, s->w_size - s->insert); 1712 } 1713 s->block_start = s->strstart; 1714 } 1715 if (s->high_water < s->strstart) 1716 s->high_water = s->strstart; 1717 1718 /* If the last block was written to next_out, then done. */ 1719 if (last) 1720 return finish_done; 1721 1722 /* If flushing and all input has been consumed, then done. */ 1723 if (flush != Z_NO_FLUSH && flush != Z_FINISH && 1724 s->strm->avail_in == 0 && (long)s->strstart == s->block_start) 1725 return block_done; 1726 1727 /* Fill the window with any remaining input. */ 1728 have = s->window_size - s->strstart; 1729 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) { 1730 /* Slide the window down. */ 1731 s->block_start -= s->w_size; 1732 s->strstart -= s->w_size; 1733 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1734 if (s->matches < 2) 1735 s->matches++; /* add a pending slide_hash() */ 1736 have += s->w_size; /* more space now */ 1737 if (s->insert > s->strstart) 1738 s->insert = s->strstart; 1739 } 1740 if (have > s->strm->avail_in) 1741 have = s->strm->avail_in; 1742 if (have) { 1743 read_buf(s->strm, s->window + s->strstart, have); 1744 s->strstart += have; 1745 s->insert += MIN(have, s->w_size - s->insert); 1746 } 1747 if (s->high_water < s->strstart) 1748 s->high_water = s->strstart; 1749 1750 /* There was not enough avail_out to write a complete worthy or flushed 1751 * stored block to next_out. Write a stored block to pending instead, if we 1752 * have enough input for a worthy block, or if flushing and there is enough 1753 * room for the remaining input as a stored block in the pending buffer. 1754 */ 1755 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1756 /* maximum stored block length that will fit in pending: */ 1757 have = MIN(s->pending_buf_size - have, MAX_STORED); 1758 min_block = MIN(have, s->w_size); 1759 left = s->strstart - s->block_start; 1760 if (left >= min_block || 1761 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH && 1762 s->strm->avail_in == 0 && left <= have)) { 1763 len = MIN(left, have); 1764 last = flush == Z_FINISH && s->strm->avail_in == 0 && 1765 len == left ? 1 : 0; 1766 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last); 1767 s->block_start += len; 1768 flush_pending(s->strm); 1769 } 1770 1771 /* We've done all we can with the available input and output. */ 1772 return last ? finish_started : need_more; 1773 } 1774 1775 /* =========================================================================== 1776 * Compress as much as possible from the input stream, return the current 1777 * block state. 1778 * This function does not perform lazy evaluation of matches and inserts 1779 * new strings in the dictionary only for unmatched strings or for short 1780 * matches. It is used only for the fast compression options. 1781 */ 1782 local block_state deflate_fast(deflate_state *s, int flush) { 1783 IPos hash_head; /* head of the hash chain */ 1784 int bflush; /* set if current block must be flushed */ 1785 1786 for (;;) { 1787 /* Make sure that we always have enough lookahead, except 1788 * at the end of the input file. We need MAX_MATCH bytes 1789 * for the next match, plus MIN_MATCH bytes to insert the 1790 * string following the next match. 1791 */ 1792 if (s->lookahead < MIN_LOOKAHEAD) { 1793 fill_window(s); 1794 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1795 return need_more; 1796 } 1797 if (s->lookahead == 0) break; /* flush the current block */ 1798 } 1799 1800 /* Insert the string window[strstart .. strstart + 2] in the 1801 * dictionary, and set hash_head to the head of the hash chain: 1802 */ 1803 hash_head = NIL; 1804 if (s->lookahead >= MIN_MATCH) { 1805 INSERT_STRING(s, s->strstart, hash_head); 1806 } 1807 1808 /* Find the longest match, discarding those <= prev_length. 1809 * At this point we have always match_length < MIN_MATCH 1810 */ 1811 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1812 /* To simplify the code, we prevent matches with the string 1813 * of window index 0 (in particular we have to avoid a match 1814 * of the string with itself at the start of the input file). 1815 */ 1816 s->match_length = longest_match (s, hash_head); 1817 /* longest_match() sets match_start */ 1818 } 1819 if (s->match_length >= MIN_MATCH) { 1820 check_match(s, s->strstart, s->match_start, s->match_length); 1821 1822 _tr_tally_dist(s, s->strstart - s->match_start, 1823 s->match_length - MIN_MATCH, bflush); 1824 1825 s->lookahead -= s->match_length; 1826 1827 /* Insert new strings in the hash table only if the match length 1828 * is not too large. This saves time but degrades compression. 1829 */ 1830 #ifndef FASTEST 1831 if (s->match_length <= s->max_insert_length && 1832 s->lookahead >= MIN_MATCH) { 1833 s->match_length--; /* string at strstart already in table */ 1834 do { 1835 s->strstart++; 1836 INSERT_STRING(s, s->strstart, hash_head); 1837 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1838 * always MIN_MATCH bytes ahead. 1839 */ 1840 } while (--s->match_length != 0); 1841 s->strstart++; 1842 } else 1843 #endif 1844 { 1845 s->strstart += s->match_length; 1846 s->match_length = 0; 1847 s->ins_h = s->window[s->strstart]; 1848 UPDATE_HASH(s, s->ins_h, s->window[s->strstart + 1]); 1849 #if MIN_MATCH != 3 1850 Call UPDATE_HASH() MIN_MATCH-3 more times 1851 #endif 1852 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1853 * matter since it will be recomputed at next deflate call. 1854 */ 1855 } 1856 } else { 1857 /* No match, output a literal byte */ 1858 Tracevv((stderr,"%c", s->window[s->strstart])); 1859 _tr_tally_lit(s, s->window[s->strstart], bflush); 1860 s->lookahead--; 1861 s->strstart++; 1862 } 1863 if (bflush) FLUSH_BLOCK(s, 0); 1864 } 1865 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1866 if (flush == Z_FINISH) { 1867 FLUSH_BLOCK(s, 1); 1868 return finish_done; 1869 } 1870 if (s->sym_next) 1871 FLUSH_BLOCK(s, 0); 1872 return block_done; 1873 } 1874 1875 #ifndef FASTEST 1876 /* =========================================================================== 1877 * Same as above, but achieves better compression. We use a lazy 1878 * evaluation for matches: a match is finally adopted only if there is 1879 * no better match at the next window position. 1880 */ 1881 local block_state deflate_slow(deflate_state *s, int flush) { 1882 IPos hash_head; /* head of hash chain */ 1883 int bflush; /* set if current block must be flushed */ 1884 1885 /* Process the input block. */ 1886 for (;;) { 1887 /* Make sure that we always have enough lookahead, except 1888 * at the end of the input file. We need MAX_MATCH bytes 1889 * for the next match, plus MIN_MATCH bytes to insert the 1890 * string following the next match. 1891 */ 1892 if (s->lookahead < MIN_LOOKAHEAD) { 1893 fill_window(s); 1894 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1895 return need_more; 1896 } 1897 if (s->lookahead == 0) break; /* flush the current block */ 1898 } 1899 1900 /* Insert the string window[strstart .. strstart + 2] in the 1901 * dictionary, and set hash_head to the head of the hash chain: 1902 */ 1903 hash_head = NIL; 1904 if (s->lookahead >= MIN_MATCH) { 1905 INSERT_STRING(s, s->strstart, hash_head); 1906 } 1907 1908 /* Find the longest match, discarding those <= prev_length. 1909 */ 1910 s->prev_length = s->match_length, s->prev_match = s->match_start; 1911 s->match_length = MIN_MATCH-1; 1912 1913 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1914 s->strstart - hash_head <= MAX_DIST(s)) { 1915 /* To simplify the code, we prevent matches with the string 1916 * of window index 0 (in particular we have to avoid a match 1917 * of the string with itself at the start of the input file). 1918 */ 1919 s->match_length = longest_match (s, hash_head); 1920 /* longest_match() sets match_start */ 1921 1922 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1923 #if TOO_FAR <= 32767 1924 || (s->match_length == MIN_MATCH && 1925 s->strstart - s->match_start > TOO_FAR) 1926 #endif 1927 )) { 1928 1929 /* If prev_match is also MIN_MATCH, match_start is garbage 1930 * but we will ignore the current match anyway. 1931 */ 1932 s->match_length = MIN_MATCH-1; 1933 } 1934 } 1935 /* If there was a match at the previous step and the current 1936 * match is not better, output the previous match: 1937 */ 1938 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1939 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1940 /* Do not insert strings in hash table beyond this. */ 1941 1942 check_match(s, s->strstart - 1, s->prev_match, s->prev_length); 1943 1944 _tr_tally_dist(s, s->strstart - 1 - s->prev_match, 1945 s->prev_length - MIN_MATCH, bflush); 1946 1947 /* Insert in hash table all strings up to the end of the match. 1948 * strstart - 1 and strstart are already inserted. If there is not 1949 * enough lookahead, the last two strings are not inserted in 1950 * the hash table. 1951 */ 1952 s->lookahead -= s->prev_length - 1; 1953 s->prev_length -= 2; 1954 do { 1955 if (++s->strstart <= max_insert) { 1956 INSERT_STRING(s, s->strstart, hash_head); 1957 } 1958 } while (--s->prev_length != 0); 1959 s->match_available = 0; 1960 s->match_length = MIN_MATCH-1; 1961 s->strstart++; 1962 1963 if (bflush) FLUSH_BLOCK(s, 0); 1964 1965 } else if (s->match_available) { 1966 /* If there was no match at the previous position, output a 1967 * single literal. If there was a match but the current match 1968 * is longer, truncate the previous match to a single literal. 1969 */ 1970 Tracevv((stderr,"%c", s->window[s->strstart - 1])); 1971 _tr_tally_lit(s, s->window[s->strstart - 1], bflush); 1972 if (bflush) { 1973 FLUSH_BLOCK_ONLY(s, 0); 1974 } 1975 s->strstart++; 1976 s->lookahead--; 1977 if (s->strm->avail_out == 0) return need_more; 1978 } else { 1979 /* There is no previous match to compare with, wait for 1980 * the next step to decide. 1981 */ 1982 s->match_available = 1; 1983 s->strstart++; 1984 s->lookahead--; 1985 } 1986 } 1987 Assert (flush != Z_NO_FLUSH, "no flush?"); 1988 if (s->match_available) { 1989 Tracevv((stderr,"%c", s->window[s->strstart - 1])); 1990 _tr_tally_lit(s, s->window[s->strstart - 1], bflush); 1991 s->match_available = 0; 1992 } 1993 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1994 if (flush == Z_FINISH) { 1995 FLUSH_BLOCK(s, 1); 1996 return finish_done; 1997 } 1998 if (s->sym_next) 1999 FLUSH_BLOCK(s, 0); 2000 return block_done; 2001 } 2002 #endif /* FASTEST */ 2003 2004 /* =========================================================================== 2005 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 2006 * one. Do not maintain a hash table. (It will be regenerated if this run of 2007 * deflate switches away from Z_RLE.) 2008 */ 2009 local block_state deflate_rle(deflate_state *s, int flush) { 2010 int bflush; /* set if current block must be flushed */ 2011 uInt prev; /* byte at distance one to match */ 2012 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 2013 2014 for (;;) { 2015 /* Make sure that we always have enough lookahead, except 2016 * at the end of the input file. We need MAX_MATCH bytes 2017 * for the longest run, plus one for the unrolled loop. 2018 */ 2019 if (s->lookahead <= MAX_MATCH) { 2020 fill_window(s); 2021 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 2022 return need_more; 2023 } 2024 if (s->lookahead == 0) break; /* flush the current block */ 2025 } 2026 2027 /* See how many times the previous byte repeats */ 2028 s->match_length = 0; 2029 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 2030 scan = s->window + s->strstart - 1; 2031 prev = *scan; 2032 if (prev == *++scan && prev == *++scan && prev == *++scan) { 2033 strend = s->window + s->strstart + MAX_MATCH; 2034 do { 2035 } while (prev == *++scan && prev == *++scan && 2036 prev == *++scan && prev == *++scan && 2037 prev == *++scan && prev == *++scan && 2038 prev == *++scan && prev == *++scan && 2039 scan < strend); 2040 s->match_length = MAX_MATCH - (uInt)(strend - scan); 2041 if (s->match_length > s->lookahead) 2042 s->match_length = s->lookahead; 2043 } 2044 Assert(scan <= s->window + (uInt)(s->window_size - 1), 2045 "wild scan"); 2046 } 2047 2048 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 2049 if (s->match_length >= MIN_MATCH) { 2050 check_match(s, s->strstart, s->strstart - 1, s->match_length); 2051 2052 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 2053 2054 s->lookahead -= s->match_length; 2055 s->strstart += s->match_length; 2056 s->match_length = 0; 2057 } else { 2058 /* No match, output a literal byte */ 2059 Tracevv((stderr,"%c", s->window[s->strstart])); 2060 _tr_tally_lit(s, s->window[s->strstart], bflush); 2061 s->lookahead--; 2062 s->strstart++; 2063 } 2064 if (bflush) FLUSH_BLOCK(s, 0); 2065 } 2066 s->insert = 0; 2067 if (flush == Z_FINISH) { 2068 FLUSH_BLOCK(s, 1); 2069 return finish_done; 2070 } 2071 if (s->sym_next) 2072 FLUSH_BLOCK(s, 0); 2073 return block_done; 2074 } 2075 2076 /* =========================================================================== 2077 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 2078 * (It will be regenerated if this run of deflate switches away from Huffman.) 2079 */ 2080 local block_state deflate_huff(deflate_state *s, int flush) { 2081 int bflush; /* set if current block must be flushed */ 2082 2083 for (;;) { 2084 /* Make sure that we have a literal to write. */ 2085 if (s->lookahead == 0) { 2086 fill_window(s); 2087 if (s->lookahead == 0) { 2088 if (flush == Z_NO_FLUSH) 2089 return need_more; 2090 break; /* flush the current block */ 2091 } 2092 } 2093 2094 /* Output a literal byte */ 2095 s->match_length = 0; 2096 Tracevv((stderr,"%c", s->window[s->strstart])); 2097 _tr_tally_lit(s, s->window[s->strstart], bflush); 2098 s->lookahead--; 2099 s->strstart++; 2100 if (bflush) FLUSH_BLOCK(s, 0); 2101 } 2102 s->insert = 0; 2103 if (flush == Z_FINISH) { 2104 FLUSH_BLOCK(s, 1); 2105 return finish_done; 2106 } 2107 if (s->sym_next) 2108 FLUSH_BLOCK(s, 0); 2109 return block_done; 2110 } 2111