1 /* deflate.c -- compress data using the deflation algorithm 2 * Copyright (C) 1995-2024 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, LIT_BUFS); 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 #ifdef LIT_MEM 503 s->d_buf = (ushf *)(s->pending_buf + (s->lit_bufsize << 1)); 504 s->l_buf = s->pending_buf + (s->lit_bufsize << 2); 505 s->sym_end = s->lit_bufsize - 1; 506 #else 507 s->sym_buf = s->pending_buf + s->lit_bufsize; 508 s->sym_end = (s->lit_bufsize - 1) * 3; 509 #endif 510 /* We avoid equality with lit_bufsize*3 because of wraparound at 64K 511 * on 16 bit machines and because stored blocks are restricted to 512 * 64K-1 bytes. 513 */ 514 515 s->level = level; 516 s->strategy = strategy; 517 s->method = (Byte)method; 518 519 return deflateReset(strm); 520 } 521 522 /* ========================================================================= 523 * Check for a valid deflate stream state. Return 0 if ok, 1 if not. 524 */ 525 local int deflateStateCheck(z_streamp strm) { 526 deflate_state *s; 527 if (strm == Z_NULL || 528 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) 529 return 1; 530 s = strm->state; 531 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE && 532 #ifdef GZIP 533 s->status != GZIP_STATE && 534 #endif 535 s->status != EXTRA_STATE && 536 s->status != NAME_STATE && 537 s->status != COMMENT_STATE && 538 s->status != HCRC_STATE && 539 s->status != BUSY_STATE && 540 s->status != FINISH_STATE)) 541 return 1; 542 return 0; 543 } 544 545 /* ========================================================================= */ 546 int ZEXPORT deflateSetDictionary(z_streamp strm, const Bytef *dictionary, 547 uInt dictLength) { 548 deflate_state *s; 549 uInt str, n; 550 int wrap; 551 unsigned avail; 552 z_const unsigned char *next; 553 554 if (deflateStateCheck(strm) || dictionary == Z_NULL) 555 return Z_STREAM_ERROR; 556 s = strm->state; 557 wrap = s->wrap; 558 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) 559 return Z_STREAM_ERROR; 560 561 /* when using zlib wrappers, compute Adler-32 for provided dictionary */ 562 if (wrap == 1) 563 strm->adler = adler32(strm->adler, dictionary, dictLength); 564 s->wrap = 0; /* avoid computing Adler-32 in read_buf */ 565 566 /* if dictionary would fill window, just replace the history */ 567 if (dictLength >= s->w_size) { 568 if (wrap == 0) { /* already empty otherwise */ 569 CLEAR_HASH(s); 570 s->strstart = 0; 571 s->block_start = 0L; 572 s->insert = 0; 573 } 574 dictionary += dictLength - s->w_size; /* use the tail */ 575 dictLength = s->w_size; 576 } 577 578 /* insert dictionary into window and hash */ 579 avail = strm->avail_in; 580 next = strm->next_in; 581 strm->avail_in = dictLength; 582 strm->next_in = (z_const Bytef *)dictionary; 583 fill_window(s); 584 while (s->lookahead >= MIN_MATCH) { 585 str = s->strstart; 586 n = s->lookahead - (MIN_MATCH-1); 587 do { 588 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 589 #ifndef FASTEST 590 s->prev[str & s->w_mask] = s->head[s->ins_h]; 591 #endif 592 s->head[s->ins_h] = (Pos)str; 593 str++; 594 } while (--n); 595 s->strstart = str; 596 s->lookahead = MIN_MATCH-1; 597 fill_window(s); 598 } 599 s->strstart += s->lookahead; 600 s->block_start = (long)s->strstart; 601 s->insert = s->lookahead; 602 s->lookahead = 0; 603 s->match_length = s->prev_length = MIN_MATCH-1; 604 s->match_available = 0; 605 strm->next_in = next; 606 strm->avail_in = avail; 607 s->wrap = wrap; 608 return Z_OK; 609 } 610 611 /* ========================================================================= */ 612 int ZEXPORT deflateGetDictionary(z_streamp strm, Bytef *dictionary, 613 uInt *dictLength) { 614 deflate_state *s; 615 uInt len; 616 617 if (deflateStateCheck(strm)) 618 return Z_STREAM_ERROR; 619 s = strm->state; 620 len = s->strstart + s->lookahead; 621 if (len > s->w_size) 622 len = s->w_size; 623 if (dictionary != Z_NULL && len) 624 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len); 625 if (dictLength != Z_NULL) 626 *dictLength = len; 627 return Z_OK; 628 } 629 630 /* ========================================================================= */ 631 int ZEXPORT deflateResetKeep(z_streamp strm) { 632 deflate_state *s; 633 634 if (deflateStateCheck(strm)) { 635 return Z_STREAM_ERROR; 636 } 637 638 strm->total_in = strm->total_out = 0; 639 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 640 strm->data_type = Z_UNKNOWN; 641 642 s = (deflate_state *)strm->state; 643 s->pending = 0; 644 s->pending_out = s->pending_buf; 645 646 if (s->wrap < 0) { 647 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 648 } 649 s->status = 650 #ifdef GZIP 651 s->wrap == 2 ? GZIP_STATE : 652 #endif 653 INIT_STATE; 654 strm->adler = 655 #ifdef GZIP 656 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 657 #endif 658 adler32(0L, Z_NULL, 0); 659 s->last_flush = -2; 660 661 _tr_init(s); 662 663 return Z_OK; 664 } 665 666 /* =========================================================================== 667 * Initialize the "longest match" routines for a new zlib stream 668 */ 669 local void lm_init(deflate_state *s) { 670 s->window_size = (ulg)2L*s->w_size; 671 672 CLEAR_HASH(s); 673 674 /* Set the default configuration parameters: 675 */ 676 s->max_lazy_match = configuration_table[s->level].max_lazy; 677 s->good_match = configuration_table[s->level].good_length; 678 s->nice_match = configuration_table[s->level].nice_length; 679 s->max_chain_length = configuration_table[s->level].max_chain; 680 681 s->strstart = 0; 682 s->block_start = 0L; 683 s->lookahead = 0; 684 s->insert = 0; 685 s->match_length = s->prev_length = MIN_MATCH-1; 686 s->match_available = 0; 687 s->ins_h = 0; 688 } 689 690 /* ========================================================================= */ 691 int ZEXPORT deflateReset(z_streamp strm) { 692 int ret; 693 694 ret = deflateResetKeep(strm); 695 if (ret == Z_OK) 696 lm_init(strm->state); 697 return ret; 698 } 699 700 /* ========================================================================= */ 701 int ZEXPORT deflateSetHeader(z_streamp strm, gz_headerp head) { 702 if (deflateStateCheck(strm) || strm->state->wrap != 2) 703 return Z_STREAM_ERROR; 704 strm->state->gzhead = head; 705 return Z_OK; 706 } 707 708 /* ========================================================================= */ 709 int ZEXPORT deflatePending(z_streamp strm, unsigned *pending, int *bits) { 710 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 711 if (pending != Z_NULL) 712 *pending = strm->state->pending; 713 if (bits != Z_NULL) 714 *bits = strm->state->bi_valid; 715 return Z_OK; 716 } 717 718 /* ========================================================================= */ 719 int ZEXPORT deflateUsed(z_streamp strm, int *bits) { 720 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 721 if (bits != Z_NULL) 722 *bits = strm->state->bi_used; 723 return Z_OK; 724 } 725 726 /* ========================================================================= */ 727 int ZEXPORT deflatePrime(z_streamp strm, int bits, int value) { 728 deflate_state *s; 729 int put; 730 731 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 732 s = strm->state; 733 #ifdef LIT_MEM 734 if (bits < 0 || bits > 16 || 735 (uchf *)s->d_buf < s->pending_out + ((Buf_size + 7) >> 3)) 736 return Z_BUF_ERROR; 737 #else 738 if (bits < 0 || bits > 16 || 739 s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3)) 740 return Z_BUF_ERROR; 741 #endif 742 do { 743 put = Buf_size - s->bi_valid; 744 if (put > bits) 745 put = bits; 746 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); 747 s->bi_valid += put; 748 _tr_flush_bits(s); 749 value >>= put; 750 bits -= put; 751 } while (bits); 752 return Z_OK; 753 } 754 755 /* ========================================================================= */ 756 int ZEXPORT deflateParams(z_streamp strm, int level, int strategy) { 757 deflate_state *s; 758 compress_func func; 759 760 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 761 s = strm->state; 762 763 #ifdef FASTEST 764 if (level != 0) level = 1; 765 #else 766 if (level == Z_DEFAULT_COMPRESSION) level = 6; 767 #endif 768 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 769 return Z_STREAM_ERROR; 770 } 771 func = configuration_table[s->level].func; 772 773 if ((strategy != s->strategy || func != configuration_table[level].func) && 774 s->last_flush != -2) { 775 /* Flush the last buffer: */ 776 int err = deflate(strm, Z_BLOCK); 777 if (err == Z_STREAM_ERROR) 778 return err; 779 if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead) 780 return Z_BUF_ERROR; 781 } 782 if (s->level != level) { 783 if (s->level == 0 && s->matches != 0) { 784 if (s->matches == 1) 785 slide_hash(s); 786 else 787 CLEAR_HASH(s); 788 s->matches = 0; 789 } 790 s->level = level; 791 s->max_lazy_match = configuration_table[level].max_lazy; 792 s->good_match = configuration_table[level].good_length; 793 s->nice_match = configuration_table[level].nice_length; 794 s->max_chain_length = configuration_table[level].max_chain; 795 } 796 s->strategy = strategy; 797 return Z_OK; 798 } 799 800 /* ========================================================================= */ 801 int ZEXPORT deflateTune(z_streamp strm, int good_length, int max_lazy, 802 int nice_length, int max_chain) { 803 deflate_state *s; 804 805 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 806 s = strm->state; 807 s->good_match = (uInt)good_length; 808 s->max_lazy_match = (uInt)max_lazy; 809 s->nice_match = nice_length; 810 s->max_chain_length = (uInt)max_chain; 811 return Z_OK; 812 } 813 814 /* ========================================================================= 815 * For the default windowBits of 15 and memLevel of 8, this function returns a 816 * close to exact, as well as small, upper bound on the compressed size. This 817 * is an expansion of ~0.03%, plus a small constant. 818 * 819 * For any setting other than those defaults for windowBits and memLevel, one 820 * of two worst case bounds is returned. This is at most an expansion of ~4% or 821 * ~13%, plus a small constant. 822 * 823 * Both the 0.03% and 4% derive from the overhead of stored blocks. The first 824 * one is for stored blocks of 16383 bytes (memLevel == 8), whereas the second 825 * is for stored blocks of 127 bytes (the worst case memLevel == 1). The 826 * expansion results from five bytes of header for each stored block. 827 * 828 * The larger expansion of 13% results from a window size less than or equal to 829 * the symbols buffer size (windowBits <= memLevel + 7). In that case some of 830 * the data being compressed may have slid out of the sliding window, impeding 831 * a stored block from being emitted. Then the only choice is a fixed or 832 * dynamic block, where a fixed block limits the maximum expansion to 9 bits 833 * per 8-bit byte, plus 10 bits for every block. The smallest block size for 834 * which this can occur is 255 (memLevel == 2). 835 * 836 * Shifts are used to approximate divisions, for speed. 837 */ 838 uLong ZEXPORT deflateBound(z_streamp strm, uLong sourceLen) { 839 deflate_state *s; 840 uLong fixedlen, storelen, wraplen; 841 842 /* upper bound for fixed blocks with 9-bit literals and length 255 843 (memLevel == 2, which is the lowest that may not use stored blocks) -- 844 ~13% overhead plus a small constant */ 845 fixedlen = sourceLen + (sourceLen >> 3) + (sourceLen >> 8) + 846 (sourceLen >> 9) + 4; 847 848 /* upper bound for stored blocks with length 127 (memLevel == 1) -- 849 ~4% overhead plus a small constant */ 850 storelen = sourceLen + (sourceLen >> 5) + (sourceLen >> 7) + 851 (sourceLen >> 11) + 7; 852 853 /* if can't get parameters, return larger bound plus a wrapper */ 854 if (deflateStateCheck(strm)) 855 return (fixedlen > storelen ? fixedlen : storelen) + 18; 856 857 /* compute wrapper length */ 858 s = strm->state; 859 switch (s->wrap < 0 ? -s->wrap : s->wrap) { 860 case 0: /* raw deflate */ 861 wraplen = 0; 862 break; 863 case 1: /* zlib wrapper */ 864 wraplen = 6 + (s->strstart ? 4 : 0); 865 break; 866 #ifdef GZIP 867 case 2: /* gzip wrapper */ 868 wraplen = 18; 869 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 870 Bytef *str; 871 if (s->gzhead->extra != Z_NULL) 872 wraplen += 2 + s->gzhead->extra_len; 873 str = s->gzhead->name; 874 if (str != Z_NULL) 875 do { 876 wraplen++; 877 } while (*str++); 878 str = s->gzhead->comment; 879 if (str != Z_NULL) 880 do { 881 wraplen++; 882 } while (*str++); 883 if (s->gzhead->hcrc) 884 wraplen += 2; 885 } 886 break; 887 #endif 888 default: /* for compiler happiness */ 889 wraplen = 18; 890 } 891 892 /* if not default parameters, return one of the conservative bounds */ 893 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 894 return (s->w_bits <= s->hash_bits && s->level ? fixedlen : storelen) + 895 wraplen; 896 897 /* default settings: return tight bound for that case -- ~0.03% overhead 898 plus a small constant */ 899 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 900 (sourceLen >> 25) + 13 - 6 + wraplen; 901 } 902 903 /* ========================================================================= 904 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 905 * IN assertion: the stream state is correct and there is enough room in 906 * pending_buf. 907 */ 908 local void putShortMSB(deflate_state *s, uInt b) { 909 put_byte(s, (Byte)(b >> 8)); 910 put_byte(s, (Byte)(b & 0xff)); 911 } 912 913 /* ========================================================================= 914 * Flush as much pending output as possible. All deflate() output, except for 915 * some deflate_stored() output, goes through this function so some 916 * applications may wish to modify it to avoid allocating a large 917 * strm->next_out buffer and copying into it. (See also read_buf()). 918 */ 919 local void flush_pending(z_streamp strm) { 920 unsigned len; 921 deflate_state *s = strm->state; 922 923 _tr_flush_bits(s); 924 len = s->pending; 925 if (len > strm->avail_out) len = strm->avail_out; 926 if (len == 0) return; 927 928 zmemcpy(strm->next_out, s->pending_out, len); 929 strm->next_out += len; 930 s->pending_out += len; 931 strm->total_out += len; 932 strm->avail_out -= len; 933 s->pending -= len; 934 if (s->pending == 0) { 935 s->pending_out = s->pending_buf; 936 } 937 } 938 939 /* =========================================================================== 940 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1]. 941 */ 942 #define HCRC_UPDATE(beg) \ 943 do { \ 944 if (s->gzhead->hcrc && s->pending > (beg)) \ 945 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \ 946 s->pending - (beg)); \ 947 } while (0) 948 949 /* ========================================================================= */ 950 int ZEXPORT deflate(z_streamp strm, int flush) { 951 int old_flush; /* value of flush param for previous deflate call */ 952 deflate_state *s; 953 954 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { 955 return Z_STREAM_ERROR; 956 } 957 s = strm->state; 958 959 if (strm->next_out == Z_NULL || 960 (strm->avail_in != 0 && strm->next_in == Z_NULL) || 961 (s->status == FINISH_STATE && flush != Z_FINISH)) { 962 ERR_RETURN(strm, Z_STREAM_ERROR); 963 } 964 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 965 966 old_flush = s->last_flush; 967 s->last_flush = flush; 968 969 /* Flush as much pending output as possible */ 970 if (s->pending != 0) { 971 flush_pending(strm); 972 if (strm->avail_out == 0) { 973 /* Since avail_out is 0, deflate will be called again with 974 * more output space, but possibly with both pending and 975 * avail_in equal to zero. There won't be anything to do, 976 * but this is not an error situation so make sure we 977 * return OK instead of BUF_ERROR at next call of deflate: 978 */ 979 s->last_flush = -1; 980 return Z_OK; 981 } 982 983 /* Make sure there is something to do and avoid duplicate consecutive 984 * flushes. For repeated and useless calls with Z_FINISH, we keep 985 * returning Z_STREAM_END instead of Z_BUF_ERROR. 986 */ 987 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 988 flush != Z_FINISH) { 989 ERR_RETURN(strm, Z_BUF_ERROR); 990 } 991 992 /* User must not provide more input after the first FINISH: */ 993 if (s->status == FINISH_STATE && strm->avail_in != 0) { 994 ERR_RETURN(strm, Z_BUF_ERROR); 995 } 996 997 /* Write the header */ 998 if (s->status == INIT_STATE && s->wrap == 0) 999 s->status = BUSY_STATE; 1000 if (s->status == INIT_STATE) { 1001 /* zlib header */ 1002 uInt header = (Z_DEFLATED + ((s->w_bits - 8) << 4)) << 8; 1003 uInt level_flags; 1004 1005 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 1006 level_flags = 0; 1007 else if (s->level < 6) 1008 level_flags = 1; 1009 else if (s->level == 6) 1010 level_flags = 2; 1011 else 1012 level_flags = 3; 1013 header |= (level_flags << 6); 1014 if (s->strstart != 0) header |= PRESET_DICT; 1015 header += 31 - (header % 31); 1016 1017 putShortMSB(s, header); 1018 1019 /* Save the adler32 of the preset dictionary: */ 1020 if (s->strstart != 0) { 1021 putShortMSB(s, (uInt)(strm->adler >> 16)); 1022 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1023 } 1024 strm->adler = adler32(0L, Z_NULL, 0); 1025 s->status = BUSY_STATE; 1026 1027 /* Compression must start with an empty pending buffer */ 1028 flush_pending(strm); 1029 if (s->pending != 0) { 1030 s->last_flush = -1; 1031 return Z_OK; 1032 } 1033 } 1034 #ifdef GZIP 1035 if (s->status == GZIP_STATE) { 1036 /* gzip header */ 1037 strm->adler = crc32(0L, Z_NULL, 0); 1038 put_byte(s, 31); 1039 put_byte(s, 139); 1040 put_byte(s, 8); 1041 if (s->gzhead == Z_NULL) { 1042 put_byte(s, 0); 1043 put_byte(s, 0); 1044 put_byte(s, 0); 1045 put_byte(s, 0); 1046 put_byte(s, 0); 1047 put_byte(s, s->level == 9 ? 2 : 1048 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 1049 4 : 0)); 1050 put_byte(s, OS_CODE); 1051 s->status = BUSY_STATE; 1052 1053 /* Compression must start with an empty pending buffer */ 1054 flush_pending(strm); 1055 if (s->pending != 0) { 1056 s->last_flush = -1; 1057 return Z_OK; 1058 } 1059 } 1060 else { 1061 put_byte(s, (s->gzhead->text ? 1 : 0) + 1062 (s->gzhead->hcrc ? 2 : 0) + 1063 (s->gzhead->extra == Z_NULL ? 0 : 4) + 1064 (s->gzhead->name == Z_NULL ? 0 : 8) + 1065 (s->gzhead->comment == Z_NULL ? 0 : 16) 1066 ); 1067 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 1068 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 1069 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 1070 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 1071 put_byte(s, s->level == 9 ? 2 : 1072 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 1073 4 : 0)); 1074 put_byte(s, s->gzhead->os & 0xff); 1075 if (s->gzhead->extra != Z_NULL) { 1076 put_byte(s, s->gzhead->extra_len & 0xff); 1077 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 1078 } 1079 if (s->gzhead->hcrc) 1080 strm->adler = crc32(strm->adler, s->pending_buf, 1081 s->pending); 1082 s->gzindex = 0; 1083 s->status = EXTRA_STATE; 1084 } 1085 } 1086 if (s->status == EXTRA_STATE) { 1087 if (s->gzhead->extra != Z_NULL) { 1088 ulg beg = s->pending; /* start of bytes to update crc */ 1089 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex; 1090 while (s->pending + left > s->pending_buf_size) { 1091 uInt copy = s->pending_buf_size - s->pending; 1092 zmemcpy(s->pending_buf + s->pending, 1093 s->gzhead->extra + s->gzindex, copy); 1094 s->pending = s->pending_buf_size; 1095 HCRC_UPDATE(beg); 1096 s->gzindex += copy; 1097 flush_pending(strm); 1098 if (s->pending != 0) { 1099 s->last_flush = -1; 1100 return Z_OK; 1101 } 1102 beg = 0; 1103 left -= copy; 1104 } 1105 zmemcpy(s->pending_buf + s->pending, 1106 s->gzhead->extra + s->gzindex, left); 1107 s->pending += left; 1108 HCRC_UPDATE(beg); 1109 s->gzindex = 0; 1110 } 1111 s->status = NAME_STATE; 1112 } 1113 if (s->status == NAME_STATE) { 1114 if (s->gzhead->name != Z_NULL) { 1115 ulg beg = s->pending; /* start of bytes to update crc */ 1116 int val; 1117 do { 1118 if (s->pending == s->pending_buf_size) { 1119 HCRC_UPDATE(beg); 1120 flush_pending(strm); 1121 if (s->pending != 0) { 1122 s->last_flush = -1; 1123 return Z_OK; 1124 } 1125 beg = 0; 1126 } 1127 val = s->gzhead->name[s->gzindex++]; 1128 put_byte(s, val); 1129 } while (val != 0); 1130 HCRC_UPDATE(beg); 1131 s->gzindex = 0; 1132 } 1133 s->status = COMMENT_STATE; 1134 } 1135 if (s->status == COMMENT_STATE) { 1136 if (s->gzhead->comment != Z_NULL) { 1137 ulg beg = s->pending; /* start of bytes to update crc */ 1138 int val; 1139 do { 1140 if (s->pending == s->pending_buf_size) { 1141 HCRC_UPDATE(beg); 1142 flush_pending(strm); 1143 if (s->pending != 0) { 1144 s->last_flush = -1; 1145 return Z_OK; 1146 } 1147 beg = 0; 1148 } 1149 val = s->gzhead->comment[s->gzindex++]; 1150 put_byte(s, val); 1151 } while (val != 0); 1152 HCRC_UPDATE(beg); 1153 } 1154 s->status = HCRC_STATE; 1155 } 1156 if (s->status == HCRC_STATE) { 1157 if (s->gzhead->hcrc) { 1158 if (s->pending + 2 > s->pending_buf_size) { 1159 flush_pending(strm); 1160 if (s->pending != 0) { 1161 s->last_flush = -1; 1162 return Z_OK; 1163 } 1164 } 1165 put_byte(s, (Byte)(strm->adler & 0xff)); 1166 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1167 strm->adler = crc32(0L, Z_NULL, 0); 1168 } 1169 s->status = BUSY_STATE; 1170 1171 /* Compression must start with an empty pending buffer */ 1172 flush_pending(strm); 1173 if (s->pending != 0) { 1174 s->last_flush = -1; 1175 return Z_OK; 1176 } 1177 } 1178 #endif 1179 1180 /* Start a new block or continue the current one. 1181 */ 1182 if (strm->avail_in != 0 || s->lookahead != 0 || 1183 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 1184 block_state bstate; 1185 1186 bstate = s->level == 0 ? deflate_stored(s, flush) : 1187 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 1188 s->strategy == Z_RLE ? deflate_rle(s, flush) : 1189 (*(configuration_table[s->level].func))(s, flush); 1190 1191 if (bstate == finish_started || bstate == finish_done) { 1192 s->status = FINISH_STATE; 1193 } 1194 if (bstate == need_more || bstate == finish_started) { 1195 if (strm->avail_out == 0) { 1196 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 1197 } 1198 return Z_OK; 1199 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 1200 * of deflate should use the same flush parameter to make sure 1201 * that the flush is complete. So we don't have to output an 1202 * empty block here, this will be done at next call. This also 1203 * ensures that for a very small output buffer, we emit at most 1204 * one empty block. 1205 */ 1206 } 1207 if (bstate == block_done) { 1208 if (flush == Z_PARTIAL_FLUSH) { 1209 _tr_align(s); 1210 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 1211 _tr_stored_block(s, (char*)0, 0L, 0); 1212 /* For a full flush, this empty block will be recognized 1213 * as a special marker by inflate_sync(). 1214 */ 1215 if (flush == Z_FULL_FLUSH) { 1216 CLEAR_HASH(s); /* forget history */ 1217 if (s->lookahead == 0) { 1218 s->strstart = 0; 1219 s->block_start = 0L; 1220 s->insert = 0; 1221 } 1222 } 1223 } 1224 flush_pending(strm); 1225 if (strm->avail_out == 0) { 1226 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 1227 return Z_OK; 1228 } 1229 } 1230 } 1231 1232 if (flush != Z_FINISH) return Z_OK; 1233 if (s->wrap <= 0) return Z_STREAM_END; 1234 1235 /* Write the trailer */ 1236 #ifdef GZIP 1237 if (s->wrap == 2) { 1238 put_byte(s, (Byte)(strm->adler & 0xff)); 1239 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1240 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 1241 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 1242 put_byte(s, (Byte)(strm->total_in & 0xff)); 1243 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 1244 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 1245 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 1246 } 1247 else 1248 #endif 1249 { 1250 putShortMSB(s, (uInt)(strm->adler >> 16)); 1251 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1252 } 1253 flush_pending(strm); 1254 /* If avail_out is zero, the application will call deflate again 1255 * to flush the rest. 1256 */ 1257 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 1258 return s->pending != 0 ? Z_OK : Z_STREAM_END; 1259 } 1260 1261 /* ========================================================================= */ 1262 int ZEXPORT deflateEnd(z_streamp strm) { 1263 int status; 1264 1265 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 1266 1267 status = strm->state->status; 1268 1269 /* Deallocate in reverse order of allocations: */ 1270 TRY_FREE(strm, strm->state->pending_buf, strm->state->pending_buf_size); 1271 TRY_FREE(strm, strm->state->head, strm->state->hash_size * sizeof(Pos)); 1272 TRY_FREE(strm, strm->state->prev, strm->state->w_size * sizeof(Pos)); 1273 TRY_FREE(strm, strm->state->window, strm->state->w_size * 2 * sizeof(Byte)); 1274 1275 ZFREE(strm, strm->state, sizeof(deflate_state)); 1276 strm->state = Z_NULL; 1277 1278 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1279 } 1280 1281 /* ========================================================================= 1282 * Copy the source state to the destination state. 1283 * To simplify the source, this is not supported for 16-bit MSDOS (which 1284 * doesn't have enough memory anyway to duplicate compression states). 1285 */ 1286 int ZEXPORT deflateCopy(z_streamp dest, z_streamp source) { 1287 #ifdef MAXSEG_64K 1288 (void)dest; 1289 (void)source; 1290 return Z_STREAM_ERROR; 1291 #else 1292 deflate_state *ds; 1293 deflate_state *ss; 1294 1295 1296 if (deflateStateCheck(source) || dest == Z_NULL) { 1297 return Z_STREAM_ERROR; 1298 } 1299 1300 ss = source->state; 1301 1302 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream)); 1303 1304 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1305 if (ds == Z_NULL) return Z_MEM_ERROR; 1306 dest->state = (struct internal_state FAR *) ds; 1307 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state)); 1308 ds->strm = dest; 1309 1310 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1311 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1312 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1313 ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, LIT_BUFS); 1314 1315 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1316 ds->pending_buf == Z_NULL) { 1317 deflateEnd (dest); 1318 return Z_MEM_ERROR; 1319 } 1320 /* following zmemcpy do not work for 16-bit MSDOS */ 1321 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1322 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos)); 1323 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos)); 1324 zmemcpy(ds->pending_buf, ss->pending_buf, ds->lit_bufsize * LIT_BUFS); 1325 1326 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1327 #ifdef LIT_MEM 1328 ds->d_buf = (ushf *)(ds->pending_buf + (ds->lit_bufsize << 1)); 1329 ds->l_buf = ds->pending_buf + (ds->lit_bufsize << 2); 1330 #else 1331 ds->sym_buf = ds->pending_buf + ds->lit_bufsize; 1332 #endif 1333 1334 ds->l_desc.dyn_tree = ds->dyn_ltree; 1335 ds->d_desc.dyn_tree = ds->dyn_dtree; 1336 ds->bl_desc.dyn_tree = ds->bl_tree; 1337 1338 return Z_OK; 1339 #endif /* MAXSEG_64K */ 1340 } 1341 1342 #ifndef FASTEST 1343 /* =========================================================================== 1344 * Set match_start to the longest match starting at the given string and 1345 * return its length. Matches shorter or equal to prev_length are discarded, 1346 * in which case the result is equal to prev_length and match_start is 1347 * garbage. 1348 * IN assertions: cur_match is the head of the hash chain for the current 1349 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1350 * OUT assertion: the match length is not greater than s->lookahead. 1351 */ 1352 local uInt longest_match(deflate_state *s, IPos cur_match) { 1353 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1354 register Bytef *scan = s->window + s->strstart; /* current string */ 1355 register Bytef *match; /* matched string */ 1356 register int len; /* length of current match */ 1357 int best_len = (int)s->prev_length; /* best match length so far */ 1358 int nice_match = s->nice_match; /* stop if match long enough */ 1359 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1360 s->strstart - (IPos)MAX_DIST(s) : NIL; 1361 /* Stop when cur_match becomes <= limit. To simplify the code, 1362 * we prevent matches with the string of window index 0. 1363 */ 1364 Posf *prev = s->prev; 1365 uInt wmask = s->w_mask; 1366 1367 #ifdef UNALIGNED_OK 1368 /* Compare two bytes at a time. Note: this is not always beneficial. 1369 * Try with and without -DUNALIGNED_OK to check. 1370 */ 1371 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1372 register ush scan_start = *(ushf*)scan; 1373 register ush scan_end = *(ushf*)(scan + best_len - 1); 1374 #else 1375 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1376 register Byte scan_end1 = scan[best_len - 1]; 1377 register Byte scan_end = scan[best_len]; 1378 #endif 1379 1380 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1381 * It is easy to get rid of this optimization if necessary. 1382 */ 1383 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1384 1385 /* Do not waste too much time if we already have a good match: */ 1386 if (s->prev_length >= s->good_match) { 1387 chain_length >>= 2; 1388 } 1389 /* Do not look for matches beyond the end of the input. This is necessary 1390 * to make deflate deterministic. 1391 */ 1392 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead; 1393 1394 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1395 "need lookahead"); 1396 1397 do { 1398 Assert(cur_match < s->strstart, "no future"); 1399 match = s->window + cur_match; 1400 1401 /* Skip to next match if the match length cannot increase 1402 * or if the match length is less than 2. Note that the checks below 1403 * for insufficient lookahead only occur occasionally for performance 1404 * reasons. Therefore uninitialized memory will be accessed, and 1405 * conditional jumps will be made that depend on those values. 1406 * However the length of the match is limited to the lookahead, so 1407 * the output of deflate is not affected by the uninitialized values. 1408 */ 1409 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1410 /* This code assumes sizeof(unsigned short) == 2. Do not use 1411 * UNALIGNED_OK if your compiler uses a different size. 1412 */ 1413 if (*(ushf*)(match + best_len - 1) != scan_end || 1414 *(ushf*)match != scan_start) continue; 1415 1416 /* It is not necessary to compare scan[2] and match[2] since they are 1417 * always equal when the other bytes match, given that the hash keys 1418 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1419 * strstart + 3, + 5, up to strstart + 257. We check for insufficient 1420 * lookahead only every 4th comparison; the 128th check will be made 1421 * at strstart + 257. If MAX_MATCH-2 is not a multiple of 8, it is 1422 * necessary to put more guard bytes at the end of the window, or 1423 * to check more often for insufficient lookahead. 1424 */ 1425 Assert(scan[2] == match[2], "scan[2]?"); 1426 scan++, match++; 1427 do { 1428 } while (*(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1429 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1430 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1431 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1432 scan < strend); 1433 /* The funny "do {}" generates better code on most compilers */ 1434 1435 /* Here, scan <= window + strstart + 257 */ 1436 Assert(scan <= s->window + (unsigned)(s->window_size - 1), 1437 "wild scan"); 1438 if (*scan == *match) scan++; 1439 1440 len = (MAX_MATCH - 1) - (int)(strend - scan); 1441 scan = strend - (MAX_MATCH-1); 1442 1443 #else /* UNALIGNED_OK */ 1444 1445 if (match[best_len] != scan_end || 1446 match[best_len - 1] != scan_end1 || 1447 *match != *scan || 1448 *++match != scan[1]) continue; 1449 1450 /* The check at best_len - 1 can be removed because it will be made 1451 * again later. (This heuristic is not always a win.) 1452 * It is not necessary to compare scan[2] and match[2] since they 1453 * are always equal when the other bytes match, given that 1454 * the hash keys are equal and that HASH_BITS >= 8. 1455 */ 1456 scan += 2, match++; 1457 Assert(*scan == *match, "match[2]?"); 1458 1459 /* We check for insufficient lookahead only every 8th comparison; 1460 * the 256th check will be made at strstart + 258. 1461 */ 1462 do { 1463 } while (*++scan == *++match && *++scan == *++match && 1464 *++scan == *++match && *++scan == *++match && 1465 *++scan == *++match && *++scan == *++match && 1466 *++scan == *++match && *++scan == *++match && 1467 scan < strend); 1468 1469 Assert(scan <= s->window + (unsigned)(s->window_size - 1), 1470 "wild scan"); 1471 1472 len = MAX_MATCH - (int)(strend - scan); 1473 scan = strend - MAX_MATCH; 1474 1475 #endif /* UNALIGNED_OK */ 1476 1477 if (len > best_len) { 1478 s->match_start = cur_match; 1479 best_len = len; 1480 if (len >= nice_match) break; 1481 #ifdef UNALIGNED_OK 1482 scan_end = *(ushf*)(scan + best_len - 1); 1483 #else 1484 scan_end1 = scan[best_len - 1]; 1485 scan_end = scan[best_len]; 1486 #endif 1487 } 1488 } while ((cur_match = prev[cur_match & wmask]) > limit 1489 && --chain_length != 0); 1490 1491 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1492 return s->lookahead; 1493 } 1494 1495 #else /* FASTEST */ 1496 1497 /* --------------------------------------------------------------------------- 1498 * Optimized version for FASTEST only 1499 */ 1500 local uInt longest_match(deflate_state *s, IPos cur_match) { 1501 register Bytef *scan = s->window + s->strstart; /* current string */ 1502 register Bytef *match; /* matched string */ 1503 register int len; /* length of current match */ 1504 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1505 1506 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1507 * It is easy to get rid of this optimization if necessary. 1508 */ 1509 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1510 1511 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1512 "need lookahead"); 1513 1514 Assert(cur_match < s->strstart, "no future"); 1515 1516 match = s->window + cur_match; 1517 1518 /* Return failure if the match length is less than 2: 1519 */ 1520 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1521 1522 /* The check at best_len - 1 can be removed because it will be made 1523 * again later. (This heuristic is not always a win.) 1524 * It is not necessary to compare scan[2] and match[2] since they 1525 * are always equal when the other bytes match, given that 1526 * the hash keys are equal and that HASH_BITS >= 8. 1527 */ 1528 scan += 2, match += 2; 1529 Assert(*scan == *match, "match[2]?"); 1530 1531 /* We check for insufficient lookahead only every 8th comparison; 1532 * the 256th check will be made at strstart + 258. 1533 */ 1534 do { 1535 } while (*++scan == *++match && *++scan == *++match && 1536 *++scan == *++match && *++scan == *++match && 1537 *++scan == *++match && *++scan == *++match && 1538 *++scan == *++match && *++scan == *++match && 1539 scan < strend); 1540 1541 Assert(scan <= s->window + (unsigned)(s->window_size - 1), "wild scan"); 1542 1543 len = MAX_MATCH - (int)(strend - scan); 1544 1545 if (len < MIN_MATCH) return MIN_MATCH - 1; 1546 1547 s->match_start = cur_match; 1548 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1549 } 1550 1551 #endif /* FASTEST */ 1552 1553 #ifdef ZLIB_DEBUG 1554 1555 #define EQUAL 0 1556 /* result of memcmp for equal strings */ 1557 1558 /* =========================================================================== 1559 * Check that the match at match_start is indeed a match. 1560 */ 1561 local void check_match(deflate_state *s, IPos start, IPos match, int length) { 1562 /* check that the match is indeed a match */ 1563 Bytef *back = s->window + (int)match, *here = s->window + start; 1564 IPos len = length; 1565 if (match == (IPos)-1) { 1566 /* match starts one byte before the current window -- just compare the 1567 subsequent length-1 bytes */ 1568 back++; 1569 here++; 1570 len--; 1571 } 1572 if (zmemcmp(back, here, len) != EQUAL) { 1573 fprintf(stderr, " start %u, match %d, length %d\n", 1574 start, (int)match, length); 1575 do { 1576 fprintf(stderr, "(%02x %02x)", *back++, *here++); 1577 } while (--len != 0); 1578 z_error("invalid match"); 1579 } 1580 if (z_verbose > 1) { 1581 fprintf(stderr,"\\[%d,%d]", start - match, length); 1582 do { putc(s->window[start++], stderr); } while (--length != 0); 1583 } 1584 } 1585 #else 1586 # define check_match(s, start, match, length) 1587 #endif /* ZLIB_DEBUG */ 1588 1589 /* =========================================================================== 1590 * Flush the current block, with given end-of-file flag. 1591 * IN assertion: strstart is set to the end of the current match. 1592 */ 1593 #define FLUSH_BLOCK_ONLY(s, last) { \ 1594 _tr_flush_block(s, (s->block_start >= 0L ? \ 1595 (charf *)&s->window[(unsigned)s->block_start] : \ 1596 (charf *)Z_NULL), \ 1597 (ulg)((long)s->strstart - s->block_start), \ 1598 (last)); \ 1599 s->block_start = s->strstart; \ 1600 flush_pending(s->strm); \ 1601 Tracev((stderr,"[FLUSH]")); \ 1602 } 1603 1604 /* Same but force premature exit if necessary. */ 1605 #define FLUSH_BLOCK(s, last) { \ 1606 FLUSH_BLOCK_ONLY(s, last); \ 1607 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1608 } 1609 1610 /* Maximum stored block length in deflate format (not including header). */ 1611 #define MAX_STORED 65535 1612 1613 #ifndef MIN 1614 /* Minimum of a and b. */ 1615 #define MIN(a, b) ((a) > (b) ? (b) : (a)) 1616 #endif 1617 1618 /* =========================================================================== 1619 * Copy without compression as much as possible from the input stream, return 1620 * the current block state. 1621 * 1622 * In case deflateParams() is used to later switch to a non-zero compression 1623 * level, s->matches (otherwise unused when storing) keeps track of the number 1624 * of hash table slides to perform. If s->matches is 1, then one hash table 1625 * slide will be done when switching. If s->matches is 2, the maximum value 1626 * allowed here, then the hash table will be cleared, since two or more slides 1627 * is the same as a clear. 1628 * 1629 * deflate_stored() is written to minimize the number of times an input byte is 1630 * copied. It is most efficient with large input and output buffers, which 1631 * maximizes the opportunities to have a single copy from next_in to next_out. 1632 */ 1633 local block_state deflate_stored(deflate_state *s, int flush) { 1634 /* Smallest worthy block size when not flushing or finishing. By default 1635 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For 1636 * large input and output buffers, the stored block size will be larger. 1637 */ 1638 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size); 1639 1640 /* Copy as many min_block or larger stored blocks directly to next_out as 1641 * possible. If flushing, copy the remaining available input to next_out as 1642 * stored blocks, if there is enough space. 1643 */ 1644 int last = 0; 1645 unsigned len, left, have; 1646 unsigned used = s->strm->avail_in; 1647 do { 1648 /* Set len to the maximum size block that we can copy directly with the 1649 * available input data and output space. Set left to how much of that 1650 * would be copied from what's left in the window. 1651 */ 1652 len = MAX_STORED; /* maximum deflate stored block length */ 1653 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1654 if (s->strm->avail_out < have) /* need room for header */ 1655 break; 1656 /* maximum stored block length that will fit in avail_out: */ 1657 have = s->strm->avail_out - have; 1658 left = s->strstart - s->block_start; /* bytes left in window */ 1659 if (len > (ulg)left + s->strm->avail_in) 1660 len = left + s->strm->avail_in; /* limit len to the input */ 1661 if (len > have) 1662 len = have; /* limit len to the output */ 1663 1664 /* If the stored block would be less than min_block in length, or if 1665 * unable to copy all of the available input when flushing, then try 1666 * copying to the window and the pending buffer instead. Also don't 1667 * write an empty block when flushing -- deflate() does that. 1668 */ 1669 if (len < min_block && ((len == 0 && flush != Z_FINISH) || 1670 flush == Z_NO_FLUSH || 1671 len != left + s->strm->avail_in)) 1672 break; 1673 1674 /* Make a dummy stored block in pending to get the header bytes, 1675 * including any pending bits. This also updates the debugging counts. 1676 */ 1677 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0; 1678 _tr_stored_block(s, (char *)0, 0L, last); 1679 1680 /* Replace the lengths in the dummy stored block with len. */ 1681 s->pending_buf[s->pending - 4] = (Bytef)len; 1682 s->pending_buf[s->pending - 3] = (Bytef)(len >> 8); 1683 s->pending_buf[s->pending - 2] = (Bytef)~len; 1684 s->pending_buf[s->pending - 1] = (Bytef)(~len >> 8); 1685 1686 /* Write the stored block header bytes. */ 1687 flush_pending(s->strm); 1688 1689 #ifdef ZLIB_DEBUG 1690 /* Update debugging counts for the data about to be copied. */ 1691 s->compressed_len += len << 3; 1692 s->bits_sent += len << 3; 1693 #endif 1694 1695 /* Copy uncompressed bytes from the window to next_out. */ 1696 if (left) { 1697 if (left > len) 1698 left = len; 1699 zmemcpy(s->strm->next_out, s->window + s->block_start, left); 1700 s->strm->next_out += left; 1701 s->strm->avail_out -= left; 1702 s->strm->total_out += left; 1703 s->block_start += left; 1704 len -= left; 1705 } 1706 1707 /* Copy uncompressed bytes directly from next_in to next_out, updating 1708 * the check value. 1709 */ 1710 if (len) { 1711 read_buf(s->strm, s->strm->next_out, len); 1712 s->strm->next_out += len; 1713 s->strm->avail_out -= len; 1714 s->strm->total_out += len; 1715 } 1716 } while (last == 0); 1717 1718 /* Update the sliding window with the last s->w_size bytes of the copied 1719 * data, or append all of the copied data to the existing window if less 1720 * than s->w_size bytes were copied. Also update the number of bytes to 1721 * insert in the hash tables, in the event that deflateParams() switches to 1722 * a non-zero compression level. 1723 */ 1724 used -= s->strm->avail_in; /* number of input bytes directly copied */ 1725 if (used) { 1726 /* If any input was used, then no unused input remains in the window, 1727 * therefore s->block_start == s->strstart. 1728 */ 1729 if (used >= s->w_size) { /* supplant the previous history */ 1730 s->matches = 2; /* clear hash */ 1731 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size); 1732 s->strstart = s->w_size; 1733 s->insert = s->strstart; 1734 } 1735 else { 1736 if (s->window_size - s->strstart <= used) { 1737 /* Slide the window down. */ 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 if (s->insert > s->strstart) 1743 s->insert = s->strstart; 1744 } 1745 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used); 1746 s->strstart += used; 1747 s->insert += MIN(used, s->w_size - s->insert); 1748 } 1749 s->block_start = s->strstart; 1750 } 1751 if (s->high_water < s->strstart) 1752 s->high_water = s->strstart; 1753 1754 /* If the last block was written to next_out, then done. */ 1755 if (last) { 1756 s->bi_used = 8; 1757 return finish_done; 1758 } 1759 1760 /* If flushing and all input has been consumed, then done. */ 1761 if (flush != Z_NO_FLUSH && flush != Z_FINISH && 1762 s->strm->avail_in == 0 && (long)s->strstart == s->block_start) 1763 return block_done; 1764 1765 /* Fill the window with any remaining input. */ 1766 have = s->window_size - s->strstart; 1767 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) { 1768 /* Slide the window down. */ 1769 s->block_start -= s->w_size; 1770 s->strstart -= s->w_size; 1771 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1772 if (s->matches < 2) 1773 s->matches++; /* add a pending slide_hash() */ 1774 have += s->w_size; /* more space now */ 1775 if (s->insert > s->strstart) 1776 s->insert = s->strstart; 1777 } 1778 if (have > s->strm->avail_in) 1779 have = s->strm->avail_in; 1780 if (have) { 1781 read_buf(s->strm, s->window + s->strstart, have); 1782 s->strstart += have; 1783 s->insert += MIN(have, s->w_size - s->insert); 1784 } 1785 if (s->high_water < s->strstart) 1786 s->high_water = s->strstart; 1787 1788 /* There was not enough avail_out to write a complete worthy or flushed 1789 * stored block to next_out. Write a stored block to pending instead, if we 1790 * have enough input for a worthy block, or if flushing and there is enough 1791 * room for the remaining input as a stored block in the pending buffer. 1792 */ 1793 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1794 /* maximum stored block length that will fit in pending: */ 1795 have = MIN(s->pending_buf_size - have, MAX_STORED); 1796 min_block = MIN(have, s->w_size); 1797 left = s->strstart - s->block_start; 1798 if (left >= min_block || 1799 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH && 1800 s->strm->avail_in == 0 && left <= have)) { 1801 len = MIN(left, have); 1802 last = flush == Z_FINISH && s->strm->avail_in == 0 && 1803 len == left ? 1 : 0; 1804 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last); 1805 s->block_start += len; 1806 flush_pending(s->strm); 1807 } 1808 1809 /* We've done all we can with the available input and output. */ 1810 if (last) 1811 s->bi_used = 8; 1812 return last ? finish_started : need_more; 1813 } 1814 1815 /* =========================================================================== 1816 * Compress as much as possible from the input stream, return the current 1817 * block state. 1818 * This function does not perform lazy evaluation of matches and inserts 1819 * new strings in the dictionary only for unmatched strings or for short 1820 * matches. It is used only for the fast compression options. 1821 */ 1822 local block_state deflate_fast(deflate_state *s, int flush) { 1823 IPos hash_head; /* head of the hash chain */ 1824 int bflush; /* set if current block must be flushed */ 1825 1826 for (;;) { 1827 /* Make sure that we always have enough lookahead, except 1828 * at the end of the input file. We need MAX_MATCH bytes 1829 * for the next match, plus MIN_MATCH bytes to insert the 1830 * string following the next match. 1831 */ 1832 if (s->lookahead < MIN_LOOKAHEAD) { 1833 fill_window(s); 1834 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1835 return need_more; 1836 } 1837 if (s->lookahead == 0) break; /* flush the current block */ 1838 } 1839 1840 /* Insert the string window[strstart .. strstart + 2] in the 1841 * dictionary, and set hash_head to the head of the hash chain: 1842 */ 1843 hash_head = NIL; 1844 if (s->lookahead >= MIN_MATCH) { 1845 INSERT_STRING(s, s->strstart, hash_head); 1846 } 1847 1848 /* Find the longest match, discarding those <= prev_length. 1849 * At this point we have always match_length < MIN_MATCH 1850 */ 1851 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1852 /* To simplify the code, we prevent matches with the string 1853 * of window index 0 (in particular we have to avoid a match 1854 * of the string with itself at the start of the input file). 1855 */ 1856 s->match_length = longest_match (s, hash_head); 1857 /* longest_match() sets match_start */ 1858 } 1859 if (s->match_length >= MIN_MATCH) { 1860 check_match(s, s->strstart, s->match_start, s->match_length); 1861 1862 _tr_tally_dist(s, s->strstart - s->match_start, 1863 s->match_length - MIN_MATCH, bflush); 1864 1865 s->lookahead -= s->match_length; 1866 1867 /* Insert new strings in the hash table only if the match length 1868 * is not too large. This saves time but degrades compression. 1869 */ 1870 #ifndef FASTEST 1871 if (s->match_length <= s->max_insert_length && 1872 s->lookahead >= MIN_MATCH) { 1873 s->match_length--; /* string at strstart already in table */ 1874 do { 1875 s->strstart++; 1876 INSERT_STRING(s, s->strstart, hash_head); 1877 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1878 * always MIN_MATCH bytes ahead. 1879 */ 1880 } while (--s->match_length != 0); 1881 s->strstart++; 1882 } else 1883 #endif 1884 { 1885 s->strstart += s->match_length; 1886 s->match_length = 0; 1887 s->ins_h = s->window[s->strstart]; 1888 UPDATE_HASH(s, s->ins_h, s->window[s->strstart + 1]); 1889 #if MIN_MATCH != 3 1890 Call UPDATE_HASH() MIN_MATCH-3 more times 1891 #endif 1892 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1893 * matter since it will be recomputed at next deflate call. 1894 */ 1895 } 1896 } else { 1897 /* No match, output a literal byte */ 1898 Tracevv((stderr,"%c", s->window[s->strstart])); 1899 _tr_tally_lit(s, s->window[s->strstart], bflush); 1900 s->lookahead--; 1901 s->strstart++; 1902 } 1903 if (bflush) FLUSH_BLOCK(s, 0); 1904 } 1905 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1906 if (flush == Z_FINISH) { 1907 FLUSH_BLOCK(s, 1); 1908 return finish_done; 1909 } 1910 if (s->sym_next) 1911 FLUSH_BLOCK(s, 0); 1912 return block_done; 1913 } 1914 1915 #ifndef FASTEST 1916 /* =========================================================================== 1917 * Same as above, but achieves better compression. We use a lazy 1918 * evaluation for matches: a match is finally adopted only if there is 1919 * no better match at the next window position. 1920 */ 1921 local block_state deflate_slow(deflate_state *s, int flush) { 1922 IPos hash_head; /* head of hash chain */ 1923 int bflush; /* set if current block must be flushed */ 1924 1925 /* Process the input block. */ 1926 for (;;) { 1927 /* Make sure that we always have enough lookahead, except 1928 * at the end of the input file. We need MAX_MATCH bytes 1929 * for the next match, plus MIN_MATCH bytes to insert the 1930 * string following the next match. 1931 */ 1932 if (s->lookahead < MIN_LOOKAHEAD) { 1933 fill_window(s); 1934 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1935 return need_more; 1936 } 1937 if (s->lookahead == 0) break; /* flush the current block */ 1938 } 1939 1940 /* Insert the string window[strstart .. strstart + 2] in the 1941 * dictionary, and set hash_head to the head of the hash chain: 1942 */ 1943 hash_head = NIL; 1944 if (s->lookahead >= MIN_MATCH) { 1945 INSERT_STRING(s, s->strstart, hash_head); 1946 } 1947 1948 /* Find the longest match, discarding those <= prev_length. 1949 */ 1950 s->prev_length = s->match_length, s->prev_match = s->match_start; 1951 s->match_length = MIN_MATCH-1; 1952 1953 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1954 s->strstart - hash_head <= MAX_DIST(s)) { 1955 /* To simplify the code, we prevent matches with the string 1956 * of window index 0 (in particular we have to avoid a match 1957 * of the string with itself at the start of the input file). 1958 */ 1959 s->match_length = longest_match (s, hash_head); 1960 /* longest_match() sets match_start */ 1961 1962 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1963 #if TOO_FAR <= 32767 1964 || (s->match_length == MIN_MATCH && 1965 s->strstart - s->match_start > TOO_FAR) 1966 #endif 1967 )) { 1968 1969 /* If prev_match is also MIN_MATCH, match_start is garbage 1970 * but we will ignore the current match anyway. 1971 */ 1972 s->match_length = MIN_MATCH-1; 1973 } 1974 } 1975 /* If there was a match at the previous step and the current 1976 * match is not better, output the previous match: 1977 */ 1978 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1979 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1980 /* Do not insert strings in hash table beyond this. */ 1981 1982 check_match(s, s->strstart - 1, s->prev_match, s->prev_length); 1983 1984 _tr_tally_dist(s, s->strstart - 1 - s->prev_match, 1985 s->prev_length - MIN_MATCH, bflush); 1986 1987 /* Insert in hash table all strings up to the end of the match. 1988 * strstart - 1 and strstart are already inserted. If there is not 1989 * enough lookahead, the last two strings are not inserted in 1990 * the hash table. 1991 */ 1992 s->lookahead -= s->prev_length - 1; 1993 s->prev_length -= 2; 1994 do { 1995 if (++s->strstart <= max_insert) { 1996 INSERT_STRING(s, s->strstart, hash_head); 1997 } 1998 } while (--s->prev_length != 0); 1999 s->match_available = 0; 2000 s->match_length = MIN_MATCH-1; 2001 s->strstart++; 2002 2003 if (bflush) FLUSH_BLOCK(s, 0); 2004 2005 } else if (s->match_available) { 2006 /* If there was no match at the previous position, output a 2007 * single literal. If there was a match but the current match 2008 * is longer, truncate the previous match to a single literal. 2009 */ 2010 Tracevv((stderr,"%c", s->window[s->strstart - 1])); 2011 _tr_tally_lit(s, s->window[s->strstart - 1], bflush); 2012 if (bflush) { 2013 FLUSH_BLOCK_ONLY(s, 0); 2014 } 2015 s->strstart++; 2016 s->lookahead--; 2017 if (s->strm->avail_out == 0) return need_more; 2018 } else { 2019 /* There is no previous match to compare with, wait for 2020 * the next step to decide. 2021 */ 2022 s->match_available = 1; 2023 s->strstart++; 2024 s->lookahead--; 2025 } 2026 } 2027 Assert (flush != Z_NO_FLUSH, "no flush?"); 2028 if (s->match_available) { 2029 Tracevv((stderr,"%c", s->window[s->strstart - 1])); 2030 _tr_tally_lit(s, s->window[s->strstart - 1], bflush); 2031 s->match_available = 0; 2032 } 2033 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 2034 if (flush == Z_FINISH) { 2035 FLUSH_BLOCK(s, 1); 2036 return finish_done; 2037 } 2038 if (s->sym_next) 2039 FLUSH_BLOCK(s, 0); 2040 return block_done; 2041 } 2042 #endif /* FASTEST */ 2043 2044 /* =========================================================================== 2045 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 2046 * one. Do not maintain a hash table. (It will be regenerated if this run of 2047 * deflate switches away from Z_RLE.) 2048 */ 2049 local block_state deflate_rle(deflate_state *s, int flush) { 2050 int bflush; /* set if current block must be flushed */ 2051 uInt prev; /* byte at distance one to match */ 2052 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 2053 2054 for (;;) { 2055 /* Make sure that we always have enough lookahead, except 2056 * at the end of the input file. We need MAX_MATCH bytes 2057 * for the longest run, plus one for the unrolled loop. 2058 */ 2059 if (s->lookahead <= MAX_MATCH) { 2060 fill_window(s); 2061 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 2062 return need_more; 2063 } 2064 if (s->lookahead == 0) break; /* flush the current block */ 2065 } 2066 2067 /* See how many times the previous byte repeats */ 2068 s->match_length = 0; 2069 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 2070 scan = s->window + s->strstart - 1; 2071 prev = *scan; 2072 if (prev == *++scan && prev == *++scan && prev == *++scan) { 2073 strend = s->window + s->strstart + MAX_MATCH; 2074 do { 2075 } while (prev == *++scan && prev == *++scan && 2076 prev == *++scan && prev == *++scan && 2077 prev == *++scan && prev == *++scan && 2078 prev == *++scan && prev == *++scan && 2079 scan < strend); 2080 s->match_length = MAX_MATCH - (uInt)(strend - scan); 2081 if (s->match_length > s->lookahead) 2082 s->match_length = s->lookahead; 2083 } 2084 Assert(scan <= s->window + (uInt)(s->window_size - 1), 2085 "wild scan"); 2086 } 2087 2088 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 2089 if (s->match_length >= MIN_MATCH) { 2090 check_match(s, s->strstart, s->strstart - 1, s->match_length); 2091 2092 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 2093 2094 s->lookahead -= s->match_length; 2095 s->strstart += s->match_length; 2096 s->match_length = 0; 2097 } else { 2098 /* No match, output a literal byte */ 2099 Tracevv((stderr,"%c", s->window[s->strstart])); 2100 _tr_tally_lit(s, s->window[s->strstart], bflush); 2101 s->lookahead--; 2102 s->strstart++; 2103 } 2104 if (bflush) FLUSH_BLOCK(s, 0); 2105 } 2106 s->insert = 0; 2107 if (flush == Z_FINISH) { 2108 FLUSH_BLOCK(s, 1); 2109 return finish_done; 2110 } 2111 if (s->sym_next) 2112 FLUSH_BLOCK(s, 0); 2113 return block_done; 2114 } 2115 2116 /* =========================================================================== 2117 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 2118 * (It will be regenerated if this run of deflate switches away from Huffman.) 2119 */ 2120 local block_state deflate_huff(deflate_state *s, int flush) { 2121 int bflush; /* set if current block must be flushed */ 2122 2123 for (;;) { 2124 /* Make sure that we have a literal to write. */ 2125 if (s->lookahead == 0) { 2126 fill_window(s); 2127 if (s->lookahead == 0) { 2128 if (flush == Z_NO_FLUSH) 2129 return need_more; 2130 break; /* flush the current block */ 2131 } 2132 } 2133 2134 /* Output a literal byte */ 2135 s->match_length = 0; 2136 Tracevv((stderr,"%c", s->window[s->strstart])); 2137 _tr_tally_lit(s, s->window[s->strstart], bflush); 2138 s->lookahead--; 2139 s->strstart++; 2140 if (bflush) FLUSH_BLOCK(s, 0); 2141 } 2142 s->insert = 0; 2143 if (flush == Z_FINISH) { 2144 FLUSH_BLOCK(s, 1); 2145 return finish_done; 2146 } 2147 if (s->sym_next) 2148 FLUSH_BLOCK(s, 0); 2149 return block_done; 2150 } 2151