1 /* $NetBSD: deflate.c,v 1.7 2024/09/22 19:12:27 christos Exp $ */ 2 3 /* deflate.c -- compress data using the deflation algorithm 4 * Copyright (C) 1995-2024 Jean-loup Gailly and Mark Adler 5 * For conditions of distribution and use, see copyright notice in zlib.h 6 */ 7 8 /* 9 * ALGORITHM 10 * 11 * The "deflation" process depends on being able to identify portions 12 * of the input text which are identical to earlier input (within a 13 * sliding window trailing behind the input currently being processed). 14 * 15 * The most straightforward technique turns out to be the fastest for 16 * most input files: try all possible matches and select the longest. 17 * The key feature of this algorithm is that insertions into the string 18 * dictionary are very simple and thus fast, and deletions are avoided 19 * completely. Insertions are performed at each input character, whereas 20 * string matches are performed only when the previous match ends. So it 21 * is preferable to spend more time in matches to allow very fast string 22 * insertions and avoid deletions. The matching algorithm for small 23 * strings is inspired from that of Rabin & Karp. A brute force approach 24 * is used to find longer strings when a small match has been found. 25 * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze 26 * (by Leonid Broukhis). 27 * A previous version of this file used a more sophisticated algorithm 28 * (by Fiala and Greene) which is guaranteed to run in linear amortized 29 * time, but has a larger average cost, uses more memory and is patented. 30 * However the F&G algorithm may be faster for some highly redundant 31 * files if the parameter max_chain_length (described below) is too large. 32 * 33 * ACKNOWLEDGEMENTS 34 * 35 * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and 36 * I found it in 'freeze' written by Leonid Broukhis. 37 * Thanks to many people for bug reports and testing. 38 * 39 * REFERENCES 40 * 41 * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification". 42 * Available in http://tools.ietf.org/html/rfc1951 43 * 44 * A description of the Rabin and Karp algorithm is given in the book 45 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252. 46 * 47 * Fiala,E.R., and Greene,D.H. 48 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595 49 * 50 */ 51 52 /* @(#) Id */ 53 54 #include "deflate.h" 55 56 const char deflate_copyright[] = 57 " deflate 1.3.1 Copyright 1995-2024 Jean-loup Gailly and Mark Adler "; 58 /* 59 If you use the zlib library in a product, an acknowledgment is welcome 60 in the documentation of your product. If for some reason you cannot 61 include such an acknowledgment, I would appreciate that you keep this 62 copyright string in the executable of your product. 63 */ 64 65 typedef enum { 66 need_more, /* block not completed, need more input or more output */ 67 block_done, /* block flush performed */ 68 finish_started, /* finish started, need only more output at next deflate */ 69 finish_done /* finish done, accept no more input or output */ 70 } block_state; 71 72 typedef block_state (*compress_func)(deflate_state *s, int flush); 73 /* Compression function. Returns the block state after the call. */ 74 75 local block_state deflate_stored(deflate_state *s, int flush); 76 local block_state deflate_fast(deflate_state *s, int flush); 77 #ifndef FASTEST 78 local block_state deflate_slow(deflate_state *s, int flush); 79 #endif 80 local block_state deflate_rle(deflate_state *s, int flush); 81 local block_state deflate_huff(deflate_state *s, int flush); 82 83 /* =========================================================================== 84 * Local data 85 */ 86 87 #define NIL 0 88 /* Tail of hash chains */ 89 90 #ifndef TOO_FAR 91 # define TOO_FAR 4096 92 #endif 93 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ 94 95 /* Values for max_lazy_match, good_match and max_chain_length, depending on 96 * the desired pack level (0..9). The values given below have been tuned to 97 * exclude worst case performance for pathological files. Better values may be 98 * found for specific files. 99 */ 100 typedef struct config_s { 101 ush good_length; /* reduce lazy search above this match length */ 102 ush max_lazy; /* do not perform lazy search above this match length */ 103 ush nice_length; /* quit search above this match length */ 104 ush max_chain; 105 compress_func func; 106 } config; 107 108 #ifdef FASTEST 109 local const config configuration_table[2] = { 110 /* good lazy nice chain */ 111 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 112 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ 113 #else 114 local const config configuration_table[10] = { 115 /* good lazy nice chain */ 116 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 117 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ 118 /* 2 */ {4, 5, 16, 8, deflate_fast}, 119 /* 3 */ {4, 6, 32, 32, deflate_fast}, 120 121 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ 122 /* 5 */ {8, 16, 32, 32, deflate_slow}, 123 /* 6 */ {8, 16, 128, 128, deflate_slow}, 124 /* 7 */ {8, 32, 128, 256, deflate_slow}, 125 /* 8 */ {32, 128, 258, 1024, deflate_slow}, 126 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ 127 #endif 128 129 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 130 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different 131 * meaning. 132 */ 133 134 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */ 135 #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0)) 136 137 /* =========================================================================== 138 * Update a hash value with the given input byte 139 * IN assertion: all calls to UPDATE_HASH are made with consecutive input 140 * characters, so that a running hash key can be computed from the previous 141 * key instead of complete recalculation each time. 142 */ 143 #define UPDATE_HASH(s,h,c) (h = (((h) << s->hash_shift) ^ (c)) & s->hash_mask) 144 145 146 /* =========================================================================== 147 * Insert string str in the dictionary and set match_head to the previous head 148 * of the hash chain (the most recent string with same hash key). Return 149 * the previous length of the hash chain. 150 * If this file is compiled with -DFASTEST, the compression level is forced 151 * to 1, and no hash chains are maintained. 152 * IN assertion: all calls to INSERT_STRING are made with consecutive input 153 * characters and the first MIN_MATCH bytes of str are valid (except for 154 * the last MIN_MATCH-1 bytes of the input file). 155 */ 156 #ifdef FASTEST 157 #define INSERT_STRING(s, str, match_head) \ 158 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 159 match_head = s->head[s->ins_h], \ 160 s->head[s->ins_h] = (Pos)(str)) 161 #else 162 #define INSERT_STRING(s, str, match_head) \ 163 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 164 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ 165 s->head[s->ins_h] = (Pos)(str)) 166 #endif 167 168 /* =========================================================================== 169 * Initialize the hash table (avoiding 64K overflow for 16 bit systems). 170 * prev[] will be initialized on the fly. 171 */ 172 #define CLEAR_HASH(s) \ 173 do { \ 174 s->head[s->hash_size - 1] = NIL; \ 175 zmemzero((Bytef *)s->head, \ 176 (unsigned)(s->hash_size - 1)*sizeof(*s->head)); \ 177 } while (0) 178 179 /* =========================================================================== 180 * Slide the hash table when sliding the window down (could be avoided with 32 181 * bit values at the expense of memory usage). We slide even when level == 0 to 182 * keep the hash table consistent if we switch back to level > 0 later. 183 */ 184 #if defined(__has_feature) 185 # if __has_feature(memory_sanitizer) 186 __attribute__((no_sanitize("memory"))) 187 # endif 188 #endif 189 local void slide_hash(deflate_state *s) { 190 unsigned n, m; 191 Posf *p; 192 uInt wsize = s->w_size; 193 194 n = s->hash_size; 195 p = &s->head[n]; 196 do { 197 m = *--p; 198 *p = (Pos)(m >= wsize ? m - wsize : NIL); 199 } while (--n); 200 n = wsize; 201 #ifndef FASTEST 202 p = &s->prev[n]; 203 do { 204 m = *--p; 205 *p = (Pos)(m >= wsize ? m - wsize : NIL); 206 /* If n is not on any hash chain, prev[n] is garbage but 207 * its value will never be used. 208 */ 209 } while (--n); 210 #endif 211 } 212 213 /* =========================================================================== 214 * Read a new buffer from the current input stream, update the adler32 215 * and total number of bytes read. All deflate() input goes through 216 * this function so some applications may wish to modify it to avoid 217 * allocating a large strm->next_in buffer and copying from it. 218 * (See also flush_pending()). 219 */ 220 local unsigned read_buf(z_streamp strm, Bytef *buf, unsigned size) { 221 unsigned len = strm->avail_in; 222 223 if (len > size) len = size; 224 if (len == 0) return 0; 225 226 strm->avail_in -= len; 227 228 zmemcpy(buf, strm->next_in, len); 229 if (strm->state->wrap == 1) { 230 strm->adler = adler32(strm->adler, buf, len); 231 } 232 #ifdef GZIP 233 else if (strm->state->wrap == 2) { 234 strm->adler = crc32(strm->adler, buf, len); 235 } 236 #endif 237 strm->next_in += len; 238 strm->total_in += len; 239 240 return len; 241 } 242 243 /* =========================================================================== 244 * Fill the window when the lookahead becomes insufficient. 245 * Updates strstart and lookahead. 246 * 247 * IN assertion: lookahead < MIN_LOOKAHEAD 248 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 249 * At least one byte has been read, or avail_in == 0; reads are 250 * performed for at least two bytes (required for the zip translate_eol 251 * option -- not supported here). 252 */ 253 local void fill_window(deflate_state *s) { 254 unsigned n; 255 unsigned more; /* Amount of free space at the end of the window. */ 256 uInt wsize = s->w_size; 257 258 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); 259 260 do { 261 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 262 263 /* Deal with !@#$% 64K limit: */ 264 if (sizeof(int) <= 2) { 265 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 266 more = wsize; 267 268 } else if (more == (unsigned)(-1)) { 269 /* Very unlikely, but possible on 16 bit machine if 270 * strstart == 0 && lookahead == 1 (input done a byte at time) 271 */ 272 more--; 273 } 274 } 275 276 /* If the window is almost full and there is insufficient lookahead, 277 * move the upper half to the lower one to make room in the upper half. 278 */ 279 if (s->strstart >= wsize + MAX_DIST(s)) { 280 281 zmemcpy(s->window, s->window + wsize, (unsigned)wsize - more); 282 s->match_start -= wsize; 283 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 284 s->block_start -= (long) wsize; 285 if (s->insert > s->strstart) 286 s->insert = s->strstart; 287 slide_hash(s); 288 more += wsize; 289 } 290 if (s->strm->avail_in == 0) break; 291 292 /* If there was no sliding: 293 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 294 * more == window_size - lookahead - strstart 295 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 296 * => more >= window_size - 2*WSIZE + 2 297 * In the BIG_MEM or MMAP case (not yet supported), 298 * window_size == input_size + MIN_LOOKAHEAD && 299 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 300 * Otherwise, window_size == 2*WSIZE so more >= 2. 301 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 302 */ 303 Assert(more >= 2, "more < 2"); 304 305 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 306 s->lookahead += n; 307 308 /* Initialize the hash value now that we have some input: */ 309 if (s->lookahead + s->insert >= MIN_MATCH) { 310 uInt str = s->strstart - s->insert; 311 s->ins_h = s->window[str]; 312 UPDATE_HASH(s, s->ins_h, s->window[str + 1]); 313 #if MIN_MATCH != 3 314 Call UPDATE_HASH() MIN_MATCH-3 more times 315 #endif 316 while (s->insert) { 317 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 318 #ifndef FASTEST 319 s->prev[str & s->w_mask] = s->head[s->ins_h]; 320 #endif 321 s->head[s->ins_h] = (Pos)str; 322 str++; 323 s->insert--; 324 if (s->lookahead + s->insert < MIN_MATCH) 325 break; 326 } 327 } 328 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 329 * but this is not important since only literal bytes will be emitted. 330 */ 331 332 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 333 334 /* If the WIN_INIT bytes after the end of the current data have never been 335 * written, then zero those bytes in order to avoid memory check reports of 336 * the use of uninitialized (or uninitialised as Julian writes) bytes by 337 * the longest match routines. Update the high water mark for the next 338 * time through here. WIN_INIT is set to MAX_MATCH since the longest match 339 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. 340 */ 341 if (s->high_water < s->window_size) { 342 ulg curr = s->strstart + (ulg)(s->lookahead); 343 ulg init; 344 345 if (s->high_water < curr) { 346 /* Previous high water mark below current data -- zero WIN_INIT 347 * bytes or up to end of window, whichever is less. 348 */ 349 init = s->window_size - curr; 350 if (init > WIN_INIT) 351 init = WIN_INIT; 352 zmemzero(s->window + curr, (unsigned)init); 353 s->high_water = curr + init; 354 } 355 else if (s->high_water < (ulg)curr + WIN_INIT) { 356 /* High water mark at or above current data, but below current data 357 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up 358 * to end of window, whichever is less. 359 */ 360 init = (ulg)curr + WIN_INIT - s->high_water; 361 if (init > s->window_size - s->high_water) 362 init = s->window_size - s->high_water; 363 zmemzero(s->window + s->high_water, (unsigned)init); 364 s->high_water += init; 365 } 366 } 367 368 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 369 "not enough room for search"); 370 } 371 372 /* ========================================================================= */ 373 int ZEXPORT deflateInit_(z_streamp strm, int level, const char *version, 374 int stream_size) { 375 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, 376 Z_DEFAULT_STRATEGY, version, stream_size); 377 /* To do: ignore strm->next_in if we use it as window */ 378 } 379 380 /* ========================================================================= */ 381 int ZEXPORT deflateInit2_(z_streamp strm, int level, int method, 382 int windowBits, int memLevel, int strategy, 383 const char *version, int stream_size) { 384 deflate_state *s; 385 int wrap = 1; 386 static const char my_version[] = ZLIB_VERSION; 387 388 if (version == Z_NULL || version[0] != my_version[0] || 389 stream_size != sizeof(z_stream)) { 390 return Z_VERSION_ERROR; 391 } 392 if (strm == Z_NULL) return Z_STREAM_ERROR; 393 394 strm->msg = Z_NULL; 395 if (strm->zalloc == (alloc_func)0) { 396 #ifdef Z_SOLO 397 return Z_STREAM_ERROR; 398 #else 399 strm->zalloc = zcalloc; 400 strm->opaque = (voidpf)0; 401 #endif 402 } 403 if (strm->zfree == (free_func)0) 404 #ifdef Z_SOLO 405 return Z_STREAM_ERROR; 406 #else 407 strm->zfree = zcfree; 408 #endif 409 410 #ifdef FASTEST 411 if (level != 0) level = 1; 412 #else 413 if (level == Z_DEFAULT_COMPRESSION) level = 6; 414 #endif 415 416 if (windowBits < 0) { /* suppress zlib wrapper */ 417 wrap = 0; 418 if (windowBits < -15) 419 return Z_STREAM_ERROR; 420 windowBits = -windowBits; 421 } 422 #ifdef GZIP 423 else if (windowBits > 15) { 424 wrap = 2; /* write gzip wrapper instead */ 425 windowBits -= 16; 426 } 427 #endif 428 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 429 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 430 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) { 431 return Z_STREAM_ERROR; 432 } 433 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 434 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 435 if (s == Z_NULL) return Z_MEM_ERROR; 436 strm->state = (struct internal_state FAR *)s; 437 s->strm = strm; 438 s->status = INIT_STATE; /* to pass state test in deflateReset() */ 439 440 s->wrap = wrap; 441 s->gzhead = Z_NULL; 442 s->w_bits = (uInt)windowBits; 443 s->w_size = 1 << s->w_bits; 444 s->w_mask = s->w_size - 1; 445 446 s->hash_bits = (uInt)memLevel + 7; 447 s->hash_size = 1 << s->hash_bits; 448 s->hash_mask = s->hash_size - 1; 449 s->hash_shift = ((s->hash_bits + MIN_MATCH-1) / MIN_MATCH); 450 451 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 452 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 453 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 454 455 s->high_water = 0; /* nothing written to s->window yet */ 456 457 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 458 459 /* We overlay pending_buf and sym_buf. This works since the average size 460 * for length/distance pairs over any compressed block is assured to be 31 461 * bits or less. 462 * 463 * Analysis: The longest fixed codes are a length code of 8 bits plus 5 464 * extra bits, for lengths 131 to 257. The longest fixed distance codes are 465 * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest 466 * possible fixed-codes length/distance pair is then 31 bits total. 467 * 468 * sym_buf starts one-fourth of the way into pending_buf. So there are 469 * three bytes in sym_buf for every four bytes in pending_buf. Each symbol 470 * in sym_buf is three bytes -- two for the distance and one for the 471 * literal/length. As each symbol is consumed, the pointer to the next 472 * sym_buf value to read moves forward three bytes. From that symbol, up to 473 * 31 bits are written to pending_buf. The closest the written pending_buf 474 * bits gets to the next sym_buf symbol to read is just before the last 475 * code is written. At that time, 31*(n - 2) bits have been written, just 476 * after 24*(n - 2) bits have been consumed from sym_buf. sym_buf starts at 477 * 8*n bits into pending_buf. (Note that the symbol buffer fills when n - 1 478 * symbols are written.) The closest the writing gets to what is unread is 479 * then n + 14 bits. Here n is lit_bufsize, which is 16384 by default, and 480 * can range from 128 to 32768. 481 * 482 * Therefore, at a minimum, there are 142 bits of space between what is 483 * written and what is read in the overlain buffers, so the symbols cannot 484 * be overwritten by the compressed data. That space is actually 139 bits, 485 * due to the three-bit fixed-code block header. 486 * 487 * That covers the case where either Z_FIXED is specified, forcing fixed 488 * codes, or when the use of fixed codes is chosen, because that choice 489 * results in a smaller compressed block than dynamic codes. That latter 490 * condition then assures that the above analysis also covers all dynamic 491 * blocks. A dynamic-code block will only be chosen to be emitted if it has 492 * fewer bits than a fixed-code block would for the same set of symbols. 493 * Therefore its average symbol length is assured to be less than 31. So 494 * the compressed data for a dynamic block also cannot overwrite the 495 * symbols from which it is being constructed. 496 */ 497 498 s->pending_buf = (uchf *) ZALLOC(strm, s->lit_bufsize, LIT_BUFS); 499 s->pending_buf_size = (ulg)s->lit_bufsize * 4; 500 501 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 502 s->pending_buf == Z_NULL) { 503 s->status = FINISH_STATE; 504 strm->msg = __UNCONST(ERR_MSG(Z_MEM_ERROR)); 505 deflateEnd (strm); 506 return Z_MEM_ERROR; 507 } 508 #ifdef LIT_MEM 509 s->d_buf = (ushf *)(s->pending_buf + (s->lit_bufsize << 1)); 510 s->l_buf = s->pending_buf + (s->lit_bufsize << 2); 511 s->sym_end = s->lit_bufsize - 1; 512 #else 513 s->sym_buf = s->pending_buf + s->lit_bufsize; 514 s->sym_end = (s->lit_bufsize - 1) * 3; 515 #endif 516 /* We avoid equality with lit_bufsize*3 because of wraparound at 64K 517 * on 16 bit machines and because stored blocks are restricted to 518 * 64K-1 bytes. 519 */ 520 521 s->level = level; 522 s->strategy = strategy; 523 s->method = (Byte)method; 524 525 return deflateReset(strm); 526 } 527 528 /* ========================================================================= 529 * Check for a valid deflate stream state. Return 0 if ok, 1 if not. 530 */ 531 local int deflateStateCheck(z_streamp strm) { 532 deflate_state *s; 533 if (strm == Z_NULL || 534 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) 535 return 1; 536 s = strm->state; 537 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE && 538 #ifdef GZIP 539 s->status != GZIP_STATE && 540 #endif 541 s->status != EXTRA_STATE && 542 s->status != NAME_STATE && 543 s->status != COMMENT_STATE && 544 s->status != HCRC_STATE && 545 s->status != BUSY_STATE && 546 s->status != FINISH_STATE)) 547 return 1; 548 return 0; 549 } 550 551 /* ========================================================================= */ 552 int ZEXPORT deflateSetDictionary(z_streamp strm, const Bytef *dictionary, 553 uInt dictLength) { 554 deflate_state *s; 555 uInt str, n; 556 int wrap; 557 unsigned avail; 558 z_const unsigned char *next; 559 560 if (deflateStateCheck(strm) || dictionary == Z_NULL) 561 return Z_STREAM_ERROR; 562 s = strm->state; 563 wrap = s->wrap; 564 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) 565 return Z_STREAM_ERROR; 566 567 /* when using zlib wrappers, compute Adler-32 for provided dictionary */ 568 if (wrap == 1) 569 strm->adler = adler32(strm->adler, dictionary, dictLength); 570 s->wrap = 0; /* avoid computing Adler-32 in read_buf */ 571 572 /* if dictionary would fill window, just replace the history */ 573 if (dictLength >= s->w_size) { 574 if (wrap == 0) { /* already empty otherwise */ 575 CLEAR_HASH(s); 576 s->strstart = 0; 577 s->block_start = 0L; 578 s->insert = 0; 579 } 580 dictionary += dictLength - s->w_size; /* use the tail */ 581 dictLength = s->w_size; 582 } 583 584 /* insert dictionary into window and hash */ 585 avail = strm->avail_in; 586 next = strm->next_in; 587 strm->avail_in = dictLength; 588 strm->next_in = __UNCONST(dictionary); 589 fill_window(s); 590 while (s->lookahead >= MIN_MATCH) { 591 str = s->strstart; 592 n = s->lookahead - (MIN_MATCH-1); 593 do { 594 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); 595 #ifndef FASTEST 596 s->prev[str & s->w_mask] = s->head[s->ins_h]; 597 #endif 598 s->head[s->ins_h] = (Pos)str; 599 str++; 600 } while (--n); 601 s->strstart = str; 602 s->lookahead = MIN_MATCH-1; 603 fill_window(s); 604 } 605 s->strstart += s->lookahead; 606 s->block_start = (long)s->strstart; 607 s->insert = s->lookahead; 608 s->lookahead = 0; 609 s->match_length = s->prev_length = MIN_MATCH-1; 610 s->match_available = 0; 611 strm->next_in = next; 612 strm->avail_in = avail; 613 s->wrap = wrap; 614 return Z_OK; 615 } 616 617 /* ========================================================================= */ 618 int ZEXPORT deflateGetDictionary(z_streamp strm, Bytef *dictionary, 619 uInt *dictLength) { 620 deflate_state *s; 621 uInt len; 622 623 if (deflateStateCheck(strm)) 624 return Z_STREAM_ERROR; 625 s = strm->state; 626 len = s->strstart + s->lookahead; 627 if (len > s->w_size) 628 len = s->w_size; 629 if (dictionary != Z_NULL && len) 630 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len); 631 if (dictLength != Z_NULL) 632 *dictLength = len; 633 return Z_OK; 634 } 635 636 /* ========================================================================= */ 637 int ZEXPORT deflateResetKeep(z_streamp strm) { 638 deflate_state *s; 639 640 if (deflateStateCheck(strm)) { 641 return Z_STREAM_ERROR; 642 } 643 644 strm->total_in = strm->total_out = 0; 645 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 646 strm->data_type = Z_UNKNOWN; 647 648 s = (deflate_state *)strm->state; 649 s->pending = 0; 650 s->pending_out = s->pending_buf; 651 652 if (s->wrap < 0) { 653 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 654 } 655 s->status = 656 #ifdef GZIP 657 s->wrap == 2 ? GZIP_STATE : 658 #endif 659 INIT_STATE; 660 strm->adler = 661 #ifdef GZIP 662 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 663 #endif 664 adler32(0L, Z_NULL, 0); 665 s->last_flush = -2; 666 667 _tr_init(s); 668 669 return Z_OK; 670 } 671 672 /* =========================================================================== 673 * Initialize the "longest match" routines for a new zlib stream 674 */ 675 local void lm_init(deflate_state *s) { 676 s->window_size = (ulg)2L*s->w_size; 677 678 CLEAR_HASH(s); 679 680 /* Set the default configuration parameters: 681 */ 682 s->max_lazy_match = configuration_table[s->level].max_lazy; 683 s->good_match = configuration_table[s->level].good_length; 684 s->nice_match = configuration_table[s->level].nice_length; 685 s->max_chain_length = configuration_table[s->level].max_chain; 686 687 s->strstart = 0; 688 s->block_start = 0L; 689 s->lookahead = 0; 690 s->insert = 0; 691 s->match_length = s->prev_length = MIN_MATCH-1; 692 s->match_available = 0; 693 s->ins_h = 0; 694 } 695 696 /* ========================================================================= */ 697 int ZEXPORT deflateReset(z_streamp strm) { 698 int ret; 699 700 ret = deflateResetKeep(strm); 701 if (ret == Z_OK) 702 lm_init(strm->state); 703 return ret; 704 } 705 706 /* ========================================================================= */ 707 int ZEXPORT deflateSetHeader(z_streamp strm, gz_headerp head) { 708 if (deflateStateCheck(strm) || strm->state->wrap != 2) 709 return Z_STREAM_ERROR; 710 strm->state->gzhead = head; 711 return Z_OK; 712 } 713 714 /* ========================================================================= */ 715 int ZEXPORT deflatePending(z_streamp strm, unsigned *pending, int *bits) { 716 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 717 if (pending != Z_NULL) 718 *pending = strm->state->pending; 719 if (bits != Z_NULL) 720 *bits = strm->state->bi_valid; 721 return Z_OK; 722 } 723 724 /* ========================================================================= */ 725 int ZEXPORT deflatePrime(z_streamp strm, int bits, int value) { 726 deflate_state *s; 727 int put; 728 729 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 730 s = strm->state; 731 #ifdef LIT_MEM 732 if (bits < 0 || bits > 16 || 733 (uchf *)s->d_buf < s->pending_out + ((Buf_size + 7) >> 3)) 734 return Z_BUF_ERROR; 735 #else 736 if (bits < 0 || bits > 16 || 737 s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3)) 738 return Z_BUF_ERROR; 739 #endif 740 do { 741 put = Buf_size - s->bi_valid; 742 if (put > bits) 743 put = bits; 744 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid); 745 s->bi_valid += put; 746 _tr_flush_bits(s); 747 value >>= put; 748 bits -= put; 749 } while (bits); 750 return Z_OK; 751 } 752 753 /* ========================================================================= */ 754 int ZEXPORT deflateParams(z_streamp strm, int level, int strategy) { 755 deflate_state *s; 756 compress_func func; 757 758 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 759 s = strm->state; 760 761 #ifdef FASTEST 762 if (level != 0) level = 1; 763 #else 764 if (level == Z_DEFAULT_COMPRESSION) level = 6; 765 #endif 766 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 767 return Z_STREAM_ERROR; 768 } 769 func = configuration_table[s->level].func; 770 771 if ((strategy != s->strategy || func != configuration_table[level].func) && 772 s->last_flush != -2) { 773 /* Flush the last buffer: */ 774 int err = deflate(strm, Z_BLOCK); 775 if (err == Z_STREAM_ERROR) 776 return err; 777 if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead) 778 return Z_BUF_ERROR; 779 } 780 if (s->level != level) { 781 if (s->level == 0 && s->matches != 0) { 782 if (s->matches == 1) 783 slide_hash(s); 784 else 785 CLEAR_HASH(s); 786 s->matches = 0; 787 } 788 s->level = level; 789 s->max_lazy_match = configuration_table[level].max_lazy; 790 s->good_match = configuration_table[level].good_length; 791 s->nice_match = configuration_table[level].nice_length; 792 s->max_chain_length = configuration_table[level].max_chain; 793 } 794 s->strategy = strategy; 795 return Z_OK; 796 } 797 798 /* ========================================================================= */ 799 int ZEXPORT deflateTune(z_streamp strm, int good_length, int max_lazy, 800 int nice_length, int max_chain) { 801 deflate_state *s; 802 803 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 804 s = strm->state; 805 s->good_match = (uInt)good_length; 806 s->max_lazy_match = (uInt)max_lazy; 807 s->nice_match = nice_length; 808 s->max_chain_length = (uInt)max_chain; 809 return Z_OK; 810 } 811 812 /* ========================================================================= 813 * For the default windowBits of 15 and memLevel of 8, this function returns a 814 * close to exact, as well as small, upper bound on the compressed size. This 815 * is an expansion of ~0.03%, plus a small constant. 816 * 817 * For any setting other than those defaults for windowBits and memLevel, one 818 * of two worst case bounds is returned. This is at most an expansion of ~4% or 819 * ~13%, plus a small constant. 820 * 821 * Both the 0.03% and 4% derive from the overhead of stored blocks. The first 822 * one is for stored blocks of 16383 bytes (memLevel == 8), whereas the second 823 * is for stored blocks of 127 bytes (the worst case memLevel == 1). The 824 * expansion results from five bytes of header for each stored block. 825 * 826 * The larger expansion of 13% results from a window size less than or equal to 827 * the symbols buffer size (windowBits <= memLevel + 7). In that case some of 828 * the data being compressed may have slid out of the sliding window, impeding 829 * a stored block from being emitted. Then the only choice is a fixed or 830 * dynamic block, where a fixed block limits the maximum expansion to 9 bits 831 * per 8-bit byte, plus 10 bits for every block. The smallest block size for 832 * which this can occur is 255 (memLevel == 2). 833 * 834 * Shifts are used to approximate divisions, for speed. 835 */ 836 uLong ZEXPORT deflateBound(z_streamp strm, uLong sourceLen) { 837 deflate_state *s; 838 uLong fixedlen, storelen, wraplen; 839 840 /* upper bound for fixed blocks with 9-bit literals and length 255 841 (memLevel == 2, which is the lowest that may not use stored blocks) -- 842 ~13% overhead plus a small constant */ 843 fixedlen = sourceLen + (sourceLen >> 3) + (sourceLen >> 8) + 844 (sourceLen >> 9) + 4; 845 846 /* upper bound for stored blocks with length 127 (memLevel == 1) -- 847 ~4% overhead plus a small constant */ 848 storelen = sourceLen + (sourceLen >> 5) + (sourceLen >> 7) + 849 (sourceLen >> 11) + 7; 850 851 /* if can't get parameters, return larger bound plus a zlib wrapper */ 852 if (deflateStateCheck(strm)) 853 return (fixedlen > storelen ? fixedlen : storelen) + 6; 854 855 /* compute wrapper length */ 856 s = strm->state; 857 switch (s->wrap) { 858 case 0: /* raw deflate */ 859 wraplen = 0; 860 break; 861 case 1: /* zlib wrapper */ 862 wraplen = 6 + (s->strstart ? 4 : 0); 863 break; 864 #ifdef GZIP 865 case 2: /* gzip wrapper */ 866 wraplen = 18; 867 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */ 868 Bytef *str; 869 if (s->gzhead->extra != Z_NULL) 870 wraplen += 2 + s->gzhead->extra_len; 871 str = s->gzhead->name; 872 if (str != Z_NULL) 873 do { 874 wraplen++; 875 } while (*str++); 876 str = s->gzhead->comment; 877 if (str != Z_NULL) 878 do { 879 wraplen++; 880 } while (*str++); 881 if (s->gzhead->hcrc) 882 wraplen += 2; 883 } 884 break; 885 #endif 886 default: /* for compiler happiness */ 887 wraplen = 6; 888 } 889 890 /* if not default parameters, return one of the conservative bounds */ 891 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 892 return (s->w_bits <= s->hash_bits && s->level ? fixedlen : storelen) + 893 wraplen; 894 895 /* default settings: return tight bound for that case -- ~0.03% overhead 896 plus a small constant */ 897 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + 898 (sourceLen >> 25) + 13 - 6 + wraplen; 899 } 900 901 /* ========================================================================= 902 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 903 * IN assertion: the stream state is correct and there is enough room in 904 * pending_buf. 905 */ 906 local void putShortMSB(deflate_state *s, uInt b) { 907 put_byte(s, (Byte)(b >> 8)); 908 put_byte(s, (Byte)(b & 0xff)); 909 } 910 911 /* ========================================================================= 912 * Flush as much pending output as possible. All deflate() output, except for 913 * some deflate_stored() output, goes through this function so some 914 * applications may wish to modify it to avoid allocating a large 915 * strm->next_out buffer and copying into it. (See also read_buf()). 916 */ 917 local void flush_pending(z_streamp strm) { 918 unsigned len; 919 deflate_state *s = strm->state; 920 921 _tr_flush_bits(s); 922 len = s->pending; 923 if (len > strm->avail_out) len = strm->avail_out; 924 if (len == 0) return; 925 926 zmemcpy(strm->next_out, s->pending_out, len); 927 strm->next_out += len; 928 s->pending_out += len; 929 strm->total_out += len; 930 strm->avail_out -= len; 931 s->pending -= len; 932 if (s->pending == 0) { 933 s->pending_out = s->pending_buf; 934 } 935 } 936 937 /* =========================================================================== 938 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1]. 939 */ 940 #define HCRC_UPDATE(beg) \ 941 do { \ 942 if (s->gzhead->hcrc && s->pending > (beg)) \ 943 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \ 944 s->pending - (beg)); \ 945 } while (0) 946 947 /* ========================================================================= */ 948 int ZEXPORT deflate(z_streamp strm, int flush) { 949 int old_flush; /* value of flush param for previous deflate call */ 950 deflate_state *s; 951 952 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { 953 return Z_STREAM_ERROR; 954 } 955 s = strm->state; 956 957 if (strm->next_out == Z_NULL || 958 (strm->avail_in != 0 && strm->next_in == Z_NULL) || 959 (s->status == FINISH_STATE && flush != Z_FINISH)) { 960 ERR_RETURN(strm, Z_STREAM_ERROR); 961 } 962 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 963 964 old_flush = s->last_flush; 965 s->last_flush = flush; 966 967 /* Flush as much pending output as possible */ 968 if (s->pending != 0) { 969 flush_pending(strm); 970 if (strm->avail_out == 0) { 971 /* Since avail_out is 0, deflate will be called again with 972 * more output space, but possibly with both pending and 973 * avail_in equal to zero. There won't be anything to do, 974 * but this is not an error situation so make sure we 975 * return OK instead of BUF_ERROR at next call of deflate: 976 */ 977 s->last_flush = -1; 978 return Z_OK; 979 } 980 981 /* Make sure there is something to do and avoid duplicate consecutive 982 * flushes. For repeated and useless calls with Z_FINISH, we keep 983 * returning Z_STREAM_END instead of Z_BUF_ERROR. 984 */ 985 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) && 986 flush != Z_FINISH) { 987 ERR_RETURN(strm, Z_BUF_ERROR); 988 } 989 990 /* User must not provide more input after the first FINISH: */ 991 if (s->status == FINISH_STATE && strm->avail_in != 0) { 992 ERR_RETURN(strm, Z_BUF_ERROR); 993 } 994 995 /* Write the header */ 996 if (s->status == INIT_STATE && s->wrap == 0) 997 s->status = BUSY_STATE; 998 if (s->status == INIT_STATE) { 999 /* zlib header */ 1000 uInt header = (Z_DEFLATED + ((s->w_bits - 8) << 4)) << 8; 1001 uInt level_flags; 1002 1003 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 1004 level_flags = 0; 1005 else if (s->level < 6) 1006 level_flags = 1; 1007 else if (s->level == 6) 1008 level_flags = 2; 1009 else 1010 level_flags = 3; 1011 header |= (level_flags << 6); 1012 if (s->strstart != 0) header |= PRESET_DICT; 1013 header += 31 - (header % 31); 1014 1015 putShortMSB(s, header); 1016 1017 /* Save the adler32 of the preset dictionary: */ 1018 if (s->strstart != 0) { 1019 putShortMSB(s, (uInt)(strm->adler >> 16)); 1020 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1021 } 1022 strm->adler = adler32(0L, Z_NULL, 0); 1023 s->status = BUSY_STATE; 1024 1025 /* Compression must start with an empty pending buffer */ 1026 flush_pending(strm); 1027 if (s->pending != 0) { 1028 s->last_flush = -1; 1029 return Z_OK; 1030 } 1031 } 1032 #ifdef GZIP 1033 if (s->status == GZIP_STATE) { 1034 /* gzip header */ 1035 strm->adler = crc32(0L, Z_NULL, 0); 1036 put_byte(s, 31); 1037 put_byte(s, 139); 1038 put_byte(s, 8); 1039 if (s->gzhead == Z_NULL) { 1040 put_byte(s, 0); 1041 put_byte(s, 0); 1042 put_byte(s, 0); 1043 put_byte(s, 0); 1044 put_byte(s, 0); 1045 put_byte(s, s->level == 9 ? 2 : 1046 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 1047 4 : 0)); 1048 put_byte(s, OS_CODE); 1049 s->status = BUSY_STATE; 1050 1051 /* Compression must start with an empty pending buffer */ 1052 flush_pending(strm); 1053 if (s->pending != 0) { 1054 s->last_flush = -1; 1055 return Z_OK; 1056 } 1057 } 1058 else { 1059 put_byte(s, (s->gzhead->text ? 1 : 0) + 1060 (s->gzhead->hcrc ? 2 : 0) + 1061 (s->gzhead->extra == Z_NULL ? 0 : 4) + 1062 (s->gzhead->name == Z_NULL ? 0 : 8) + 1063 (s->gzhead->comment == Z_NULL ? 0 : 16) 1064 ); 1065 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 1066 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 1067 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 1068 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 1069 put_byte(s, s->level == 9 ? 2 : 1070 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 1071 4 : 0)); 1072 put_byte(s, s->gzhead->os & 0xff); 1073 if (s->gzhead->extra != Z_NULL) { 1074 put_byte(s, s->gzhead->extra_len & 0xff); 1075 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 1076 } 1077 if (s->gzhead->hcrc) 1078 strm->adler = crc32(strm->adler, s->pending_buf, 1079 s->pending); 1080 s->gzindex = 0; 1081 s->status = EXTRA_STATE; 1082 } 1083 } 1084 if (s->status == EXTRA_STATE) { 1085 if (s->gzhead->extra != Z_NULL) { 1086 ulg beg = s->pending; /* start of bytes to update crc */ 1087 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex; 1088 while (s->pending + left > s->pending_buf_size) { 1089 uInt copy = s->pending_buf_size - s->pending; 1090 zmemcpy(s->pending_buf + s->pending, 1091 s->gzhead->extra + s->gzindex, copy); 1092 s->pending = s->pending_buf_size; 1093 HCRC_UPDATE(beg); 1094 s->gzindex += copy; 1095 flush_pending(strm); 1096 if (s->pending != 0) { 1097 s->last_flush = -1; 1098 return Z_OK; 1099 } 1100 beg = 0; 1101 left -= copy; 1102 } 1103 zmemcpy(s->pending_buf + s->pending, 1104 s->gzhead->extra + s->gzindex, left); 1105 s->pending += left; 1106 HCRC_UPDATE(beg); 1107 s->gzindex = 0; 1108 } 1109 s->status = NAME_STATE; 1110 } 1111 if (s->status == NAME_STATE) { 1112 if (s->gzhead->name != Z_NULL) { 1113 ulg beg = s->pending; /* start of bytes to update crc */ 1114 int val; 1115 do { 1116 if (s->pending == s->pending_buf_size) { 1117 HCRC_UPDATE(beg); 1118 flush_pending(strm); 1119 if (s->pending != 0) { 1120 s->last_flush = -1; 1121 return Z_OK; 1122 } 1123 beg = 0; 1124 } 1125 val = s->gzhead->name[s->gzindex++]; 1126 put_byte(s, val); 1127 } while (val != 0); 1128 HCRC_UPDATE(beg); 1129 s->gzindex = 0; 1130 } 1131 s->status = COMMENT_STATE; 1132 } 1133 if (s->status == COMMENT_STATE) { 1134 if (s->gzhead->comment != Z_NULL) { 1135 ulg beg = s->pending; /* start of bytes to update crc */ 1136 int val; 1137 do { 1138 if (s->pending == s->pending_buf_size) { 1139 HCRC_UPDATE(beg); 1140 flush_pending(strm); 1141 if (s->pending != 0) { 1142 s->last_flush = -1; 1143 return Z_OK; 1144 } 1145 beg = 0; 1146 } 1147 val = s->gzhead->comment[s->gzindex++]; 1148 put_byte(s, val); 1149 } while (val != 0); 1150 HCRC_UPDATE(beg); 1151 } 1152 s->status = HCRC_STATE; 1153 } 1154 if (s->status == HCRC_STATE) { 1155 if (s->gzhead->hcrc) { 1156 if (s->pending + 2 > s->pending_buf_size) { 1157 flush_pending(strm); 1158 if (s->pending != 0) { 1159 s->last_flush = -1; 1160 return Z_OK; 1161 } 1162 } 1163 put_byte(s, (Byte)(strm->adler & 0xff)); 1164 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1165 strm->adler = crc32(0L, Z_NULL, 0); 1166 } 1167 s->status = BUSY_STATE; 1168 1169 /* Compression must start with an empty pending buffer */ 1170 flush_pending(strm); 1171 if (s->pending != 0) { 1172 s->last_flush = -1; 1173 return Z_OK; 1174 } 1175 } 1176 #endif 1177 1178 /* Start a new block or continue the current one. 1179 */ 1180 if (strm->avail_in != 0 || s->lookahead != 0 || 1181 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 1182 block_state bstate; 1183 1184 bstate = s->level == 0 ? deflate_stored(s, flush) : 1185 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : 1186 s->strategy == Z_RLE ? deflate_rle(s, flush) : 1187 (*(configuration_table[s->level].func))(s, flush); 1188 1189 if (bstate == finish_started || bstate == finish_done) { 1190 s->status = FINISH_STATE; 1191 } 1192 if (bstate == need_more || bstate == finish_started) { 1193 if (strm->avail_out == 0) { 1194 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 1195 } 1196 return Z_OK; 1197 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 1198 * of deflate should use the same flush parameter to make sure 1199 * that the flush is complete. So we don't have to output an 1200 * empty block here, this will be done at next call. This also 1201 * ensures that for a very small output buffer, we emit at most 1202 * one empty block. 1203 */ 1204 } 1205 if (bstate == block_done) { 1206 if (flush == Z_PARTIAL_FLUSH) { 1207 _tr_align(s); 1208 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ 1209 _tr_stored_block(s, (char*)0, 0L, 0); 1210 /* For a full flush, this empty block will be recognized 1211 * as a special marker by inflate_sync(). 1212 */ 1213 if (flush == Z_FULL_FLUSH) { 1214 CLEAR_HASH(s); /* forget history */ 1215 if (s->lookahead == 0) { 1216 s->strstart = 0; 1217 s->block_start = 0L; 1218 s->insert = 0; 1219 } 1220 } 1221 } 1222 flush_pending(strm); 1223 if (strm->avail_out == 0) { 1224 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 1225 return Z_OK; 1226 } 1227 } 1228 } 1229 1230 if (flush != Z_FINISH) return Z_OK; 1231 if (s->wrap <= 0) return Z_STREAM_END; 1232 1233 /* Write the trailer */ 1234 #ifdef GZIP 1235 if (s->wrap == 2) { 1236 put_byte(s, (Byte)(strm->adler & 0xff)); 1237 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 1238 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 1239 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 1240 put_byte(s, (Byte)(strm->total_in & 0xff)); 1241 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 1242 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 1243 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 1244 } 1245 else 1246 #endif 1247 { 1248 putShortMSB(s, (uInt)(strm->adler >> 16)); 1249 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 1250 } 1251 flush_pending(strm); 1252 /* If avail_out is zero, the application will call deflate again 1253 * to flush the rest. 1254 */ 1255 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 1256 return s->pending != 0 ? Z_OK : Z_STREAM_END; 1257 } 1258 1259 /* ========================================================================= */ 1260 int ZEXPORT deflateEnd(z_streamp strm) { 1261 int status; 1262 1263 if (deflateStateCheck(strm)) return Z_STREAM_ERROR; 1264 1265 status = strm->state->status; 1266 1267 /* Deallocate in reverse order of allocations: */ 1268 TRY_FREE(strm, strm->state->pending_buf); 1269 TRY_FREE(strm, strm->state->head); 1270 TRY_FREE(strm, strm->state->prev); 1271 TRY_FREE(strm, strm->state->window); 1272 1273 ZFREE(strm, strm->state); 1274 strm->state = Z_NULL; 1275 1276 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 1277 } 1278 1279 /* ========================================================================= 1280 * Copy the source state to the destination state. 1281 * To simplify the source, this is not supported for 16-bit MSDOS (which 1282 * doesn't have enough memory anyway to duplicate compression states). 1283 */ 1284 int ZEXPORT deflateCopy(z_streamp dest, z_streamp source) { 1285 #ifdef MAXSEG_64K 1286 (void)dest; 1287 (void)source; 1288 return Z_STREAM_ERROR; 1289 #else 1290 deflate_state *ds; 1291 deflate_state *ss; 1292 1293 1294 if (deflateStateCheck(source) || dest == Z_NULL) { 1295 return Z_STREAM_ERROR; 1296 } 1297 1298 ss = source->state; 1299 1300 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream)); 1301 1302 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 1303 if (ds == Z_NULL) return Z_MEM_ERROR; 1304 dest->state = (struct internal_state FAR *) ds; 1305 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state)); 1306 ds->strm = dest; 1307 1308 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 1309 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 1310 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 1311 ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, LIT_BUFS); 1312 1313 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 1314 ds->pending_buf == Z_NULL) { 1315 deflateEnd (dest); 1316 return Z_MEM_ERROR; 1317 } 1318 /* following zmemcpy do not work for 16-bit MSDOS */ 1319 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 1320 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos)); 1321 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos)); 1322 zmemcpy(ds->pending_buf, ss->pending_buf, ds->lit_bufsize * LIT_BUFS); 1323 1324 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 1325 #ifdef LIT_MEM 1326 ds->d_buf = (ushf *)(ds->pending_buf + (ds->lit_bufsize << 1)); 1327 ds->l_buf = ds->pending_buf + (ds->lit_bufsize << 2); 1328 #else 1329 ds->sym_buf = ds->pending_buf + ds->lit_bufsize; 1330 #endif 1331 1332 ds->l_desc.dyn_tree = ds->dyn_ltree; 1333 ds->d_desc.dyn_tree = ds->dyn_dtree; 1334 ds->bl_desc.dyn_tree = ds->bl_tree; 1335 1336 return Z_OK; 1337 #endif /* MAXSEG_64K */ 1338 } 1339 1340 #ifndef FASTEST 1341 /* =========================================================================== 1342 * Set match_start to the longest match starting at the given string and 1343 * return its length. Matches shorter or equal to prev_length are discarded, 1344 * in which case the result is equal to prev_length and match_start is 1345 * garbage. 1346 * IN assertions: cur_match is the head of the hash chain for the current 1347 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1348 * OUT assertion: the match length is not greater than s->lookahead. 1349 */ 1350 local uInt longest_match(deflate_state *s, IPos cur_match) { 1351 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1352 register Bytef *scan = s->window + s->strstart; /* current string */ 1353 register Bytef *match; /* matched string */ 1354 register int len; /* length of current match */ 1355 int best_len = (int)s->prev_length; /* best match length so far */ 1356 int nice_match = s->nice_match; /* stop if match long enough */ 1357 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1358 s->strstart - (IPos)MAX_DIST(s) : NIL; 1359 /* Stop when cur_match becomes <= limit. To simplify the code, 1360 * we prevent matches with the string of window index 0. 1361 */ 1362 Posf *prev = s->prev; 1363 uInt wmask = s->w_mask; 1364 1365 #ifdef UNALIGNED_OK 1366 /* Compare two bytes at a time. Note: this is not always beneficial. 1367 * Try with and without -DUNALIGNED_OK to check. 1368 */ 1369 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1370 register ush scan_start = *(ushf*)scan; 1371 register ush scan_end = *(ushf*)(scan + best_len - 1); 1372 #else 1373 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1374 register Byte scan_end1 = scan[best_len - 1]; 1375 register Byte scan_end = scan[best_len]; 1376 #endif 1377 1378 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1379 * It is easy to get rid of this optimization if necessary. 1380 */ 1381 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1382 1383 /* Do not waste too much time if we already have a good match: */ 1384 if (s->prev_length >= s->good_match) { 1385 chain_length >>= 2; 1386 } 1387 /* Do not look for matches beyond the end of the input. This is necessary 1388 * to make deflate deterministic. 1389 */ 1390 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead; 1391 1392 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1393 "need lookahead"); 1394 1395 do { 1396 Assert(cur_match < s->strstart, "no future"); 1397 match = s->window + cur_match; 1398 1399 /* Skip to next match if the match length cannot increase 1400 * or if the match length is less than 2. Note that the checks below 1401 * for insufficient lookahead only occur occasionally for performance 1402 * reasons. Therefore uninitialized memory will be accessed, and 1403 * conditional jumps will be made that depend on those values. 1404 * However the length of the match is limited to the lookahead, so 1405 * the output of deflate is not affected by the uninitialized values. 1406 */ 1407 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1408 /* This code assumes sizeof(unsigned short) == 2. Do not use 1409 * UNALIGNED_OK if your compiler uses a different size. 1410 */ 1411 if (*(ushf*)(match + best_len - 1) != scan_end || 1412 *(ushf*)match != scan_start) continue; 1413 1414 /* It is not necessary to compare scan[2] and match[2] since they are 1415 * always equal when the other bytes match, given that the hash keys 1416 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1417 * strstart + 3, + 5, up to strstart + 257. We check for insufficient 1418 * lookahead only every 4th comparison; the 128th check will be made 1419 * at strstart + 257. If MAX_MATCH-2 is not a multiple of 8, it is 1420 * necessary to put more guard bytes at the end of the window, or 1421 * to check more often for insufficient lookahead. 1422 */ 1423 Assert(scan[2] == match[2], "scan[2]?"); 1424 scan++, match++; 1425 do { 1426 } while (*(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1427 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1428 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1429 *(ushf*)(scan += 2) == *(ushf*)(match += 2) && 1430 scan < strend); 1431 /* The funny "do {}" generates better code on most compilers */ 1432 1433 /* Here, scan <= window + strstart + 257 */ 1434 Assert(scan <= s->window + (unsigned)(s->window_size - 1), 1435 "wild scan"); 1436 if (*scan == *match) scan++; 1437 1438 len = (MAX_MATCH - 1) - (int)(strend - scan); 1439 scan = strend - (MAX_MATCH-1); 1440 1441 #else /* UNALIGNED_OK */ 1442 1443 if (match[best_len] != scan_end || 1444 match[best_len - 1] != scan_end1 || 1445 *match != *scan || 1446 *++match != scan[1]) continue; 1447 1448 /* The check at best_len - 1 can be removed because it will be made 1449 * again later. (This heuristic is not always a win.) 1450 * It is not necessary to compare scan[2] and match[2] since they 1451 * are always equal when the other bytes match, given that 1452 * the hash keys are equal and that HASH_BITS >= 8. 1453 */ 1454 scan += 2, match++; 1455 Assert(*scan == *match, "match[2]?"); 1456 1457 /* We check for insufficient lookahead only every 8th comparison; 1458 * the 256th check will be made at strstart + 258. 1459 */ 1460 do { 1461 } while (*++scan == *++match && *++scan == *++match && 1462 *++scan == *++match && *++scan == *++match && 1463 *++scan == *++match && *++scan == *++match && 1464 *++scan == *++match && *++scan == *++match && 1465 scan < strend); 1466 1467 Assert(scan <= s->window + (unsigned)(s->window_size - 1), 1468 "wild scan"); 1469 1470 len = MAX_MATCH - (int)(strend - scan); 1471 scan = strend - MAX_MATCH; 1472 1473 #endif /* UNALIGNED_OK */ 1474 1475 if (len > best_len) { 1476 s->match_start = cur_match; 1477 best_len = len; 1478 if (len >= nice_match) break; 1479 #ifdef UNALIGNED_OK 1480 scan_end = *(ushf*)(scan + best_len - 1); 1481 #else 1482 scan_end1 = scan[best_len - 1]; 1483 scan_end = scan[best_len]; 1484 #endif 1485 } 1486 } while ((cur_match = prev[cur_match & wmask]) > limit 1487 && --chain_length != 0); 1488 1489 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1490 return s->lookahead; 1491 } 1492 1493 #else /* FASTEST */ 1494 1495 /* --------------------------------------------------------------------------- 1496 * Optimized version for FASTEST only 1497 */ 1498 local uInt longest_match(deflate_state *s, IPos cur_match) { 1499 register Bytef *scan = s->window + s->strstart; /* current string */ 1500 register Bytef *match; /* matched string */ 1501 register int len; /* length of current match */ 1502 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1503 1504 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1505 * It is easy to get rid of this optimization if necessary. 1506 */ 1507 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1508 1509 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, 1510 "need lookahead"); 1511 1512 Assert(cur_match < s->strstart, "no future"); 1513 1514 match = s->window + cur_match; 1515 1516 /* Return failure if the match length is less than 2: 1517 */ 1518 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1519 1520 /* The check at best_len - 1 can be removed because it will be made 1521 * again later. (This heuristic is not always a win.) 1522 * It is not necessary to compare scan[2] and match[2] since they 1523 * are always equal when the other bytes match, given that 1524 * the hash keys are equal and that HASH_BITS >= 8. 1525 */ 1526 scan += 2, match += 2; 1527 Assert(*scan == *match, "match[2]?"); 1528 1529 /* We check for insufficient lookahead only every 8th comparison; 1530 * the 256th check will be made at strstart + 258. 1531 */ 1532 do { 1533 } while (*++scan == *++match && *++scan == *++match && 1534 *++scan == *++match && *++scan == *++match && 1535 *++scan == *++match && *++scan == *++match && 1536 *++scan == *++match && *++scan == *++match && 1537 scan < strend); 1538 1539 Assert(scan <= s->window + (unsigned)(s->window_size - 1), "wild scan"); 1540 1541 len = MAX_MATCH - (int)(strend - scan); 1542 1543 if (len < MIN_MATCH) return MIN_MATCH - 1; 1544 1545 s->match_start = cur_match; 1546 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1547 } 1548 1549 #endif /* FASTEST */ 1550 1551 #ifdef ZLIB_DEBUG 1552 1553 #define EQUAL 0 1554 /* result of memcmp for equal strings */ 1555 1556 /* =========================================================================== 1557 * Check that the match at match_start is indeed a match. 1558 */ 1559 local void check_match(deflate_state *s, IPos start, IPos match, int length) { 1560 /* check that the match is indeed a match */ 1561 Bytef *back = s->window + (int)match, *here = s->window + start; 1562 IPos len = length; 1563 if (match == (IPos)-1) { 1564 /* match starts one byte before the current window -- just compare the 1565 subsequent length-1 bytes */ 1566 back++; 1567 here++; 1568 len--; 1569 } 1570 if (zmemcmp(back, here, len) != EQUAL) { 1571 fprintf(stderr, " start %u, match %d, length %d\n", 1572 start, (int)match, length); 1573 do { 1574 fprintf(stderr, "(%02x %02x)", *back++, *here++); 1575 } while (--len != 0); 1576 z_error("invalid match"); 1577 } 1578 if (z_verbose > 1) { 1579 fprintf(stderr,"\\[%d,%d]", start - match, length); 1580 do { putc(s->window[start++], stderr); } while (--length != 0); 1581 } 1582 } 1583 #else 1584 # define check_match(s, start, match, length) 1585 #endif /* ZLIB_DEBUG */ 1586 1587 /* =========================================================================== 1588 * Flush the current block, with given end-of-file flag. 1589 * IN assertion: strstart is set to the end of the current match. 1590 */ 1591 #define FLUSH_BLOCK_ONLY(s, last) { \ 1592 _tr_flush_block(s, (s->block_start >= 0L ? \ 1593 (charf *)&s->window[(unsigned)s->block_start] : \ 1594 (charf *)Z_NULL), \ 1595 (ulg)((long)s->strstart - s->block_start), \ 1596 (last)); \ 1597 s->block_start = s->strstart; \ 1598 flush_pending(s->strm); \ 1599 Tracev((stderr,"[FLUSH]")); \ 1600 } 1601 1602 /* Same but force premature exit if necessary. */ 1603 #define FLUSH_BLOCK(s, last) { \ 1604 FLUSH_BLOCK_ONLY(s, last); \ 1605 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ 1606 } 1607 1608 /* Maximum stored block length in deflate format (not including header). */ 1609 #define MAX_STORED 65535 1610 1611 /* Minimum of a and b. */ 1612 #define MIN(a, b) ((a) > (b) ? (b) : (a)) 1613 1614 /* =========================================================================== 1615 * Copy without compression as much as possible from the input stream, return 1616 * the current block state. 1617 * 1618 * In case deflateParams() is used to later switch to a non-zero compression 1619 * level, s->matches (otherwise unused when storing) keeps track of the number 1620 * of hash table slides to perform. If s->matches is 1, then one hash table 1621 * slide will be done when switching. If s->matches is 2, the maximum value 1622 * allowed here, then the hash table will be cleared, since two or more slides 1623 * is the same as a clear. 1624 * 1625 * deflate_stored() is written to minimize the number of times an input byte is 1626 * copied. It is most efficient with large input and output buffers, which 1627 * maximizes the opportunities to have a single copy from next_in to next_out. 1628 */ 1629 local block_state deflate_stored(deflate_state *s, int flush) { 1630 /* Smallest worthy block size when not flushing or finishing. By default 1631 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For 1632 * large input and output buffers, the stored block size will be larger. 1633 */ 1634 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size); 1635 1636 /* Copy as many min_block or larger stored blocks directly to next_out as 1637 * possible. If flushing, copy the remaining available input to next_out as 1638 * stored blocks, if there is enough space. 1639 */ 1640 unsigned len, left, have, last = 0; 1641 unsigned used = s->strm->avail_in; 1642 do { 1643 /* Set len to the maximum size block that we can copy directly with the 1644 * available input data and output space. Set left to how much of that 1645 * would be copied from what's left in the window. 1646 */ 1647 len = MAX_STORED; /* maximum deflate stored block length */ 1648 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1649 if (s->strm->avail_out < have) /* need room for header */ 1650 break; 1651 /* maximum stored block length that will fit in avail_out: */ 1652 have = s->strm->avail_out - have; 1653 left = s->strstart - s->block_start; /* bytes left in window */ 1654 if (len > (ulg)left + s->strm->avail_in) 1655 len = left + s->strm->avail_in; /* limit len to the input */ 1656 if (len > have) 1657 len = have; /* limit len to the output */ 1658 1659 /* If the stored block would be less than min_block in length, or if 1660 * unable to copy all of the available input when flushing, then try 1661 * copying to the window and the pending buffer instead. Also don't 1662 * write an empty block when flushing -- deflate() does that. 1663 */ 1664 if (len < min_block && ((len == 0 && flush != Z_FINISH) || 1665 flush == Z_NO_FLUSH || 1666 len != left + s->strm->avail_in)) 1667 break; 1668 1669 /* Make a dummy stored block in pending to get the header bytes, 1670 * including any pending bits. This also updates the debugging counts. 1671 */ 1672 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0; 1673 _tr_stored_block(s, (char *)0, 0L, last); 1674 1675 /* Replace the lengths in the dummy stored block with len. */ 1676 s->pending_buf[s->pending - 4] = len; 1677 s->pending_buf[s->pending - 3] = len >> 8; 1678 s->pending_buf[s->pending - 2] = ~len; 1679 s->pending_buf[s->pending - 1] = ~len >> 8; 1680 1681 /* Write the stored block header bytes. */ 1682 flush_pending(s->strm); 1683 1684 #ifdef ZLIB_DEBUG 1685 /* Update debugging counts for the data about to be copied. */ 1686 s->compressed_len += len << 3; 1687 s->bits_sent += len << 3; 1688 #endif 1689 1690 /* Copy uncompressed bytes from the window to next_out. */ 1691 if (left) { 1692 if (left > len) 1693 left = len; 1694 zmemcpy(s->strm->next_out, s->window + s->block_start, left); 1695 s->strm->next_out += left; 1696 s->strm->avail_out -= left; 1697 s->strm->total_out += left; 1698 s->block_start += left; 1699 len -= left; 1700 } 1701 1702 /* Copy uncompressed bytes directly from next_in to next_out, updating 1703 * the check value. 1704 */ 1705 if (len) { 1706 read_buf(s->strm, s->strm->next_out, len); 1707 s->strm->next_out += len; 1708 s->strm->avail_out -= len; 1709 s->strm->total_out += len; 1710 } 1711 } while (last == 0); 1712 1713 /* Update the sliding window with the last s->w_size bytes of the copied 1714 * data, or append all of the copied data to the existing window if less 1715 * than s->w_size bytes were copied. Also update the number of bytes to 1716 * insert in the hash tables, in the event that deflateParams() switches to 1717 * a non-zero compression level. 1718 */ 1719 used -= s->strm->avail_in; /* number of input bytes directly copied */ 1720 if (used) { 1721 /* If any input was used, then no unused input remains in the window, 1722 * therefore s->block_start == s->strstart. 1723 */ 1724 if (used >= s->w_size) { /* supplant the previous history */ 1725 s->matches = 2; /* clear hash */ 1726 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size); 1727 s->strstart = s->w_size; 1728 s->insert = s->strstart; 1729 } 1730 else { 1731 if (s->window_size - s->strstart <= used) { 1732 /* Slide the window down. */ 1733 s->strstart -= s->w_size; 1734 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1735 if (s->matches < 2) 1736 s->matches++; /* add a pending slide_hash() */ 1737 if (s->insert > s->strstart) 1738 s->insert = s->strstart; 1739 } 1740 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used); 1741 s->strstart += used; 1742 s->insert += MIN(used, s->w_size - s->insert); 1743 } 1744 s->block_start = s->strstart; 1745 } 1746 if (s->high_water < s->strstart) 1747 s->high_water = s->strstart; 1748 1749 /* If the last block was written to next_out, then done. */ 1750 if (last) 1751 return finish_done; 1752 1753 /* If flushing and all input has been consumed, then done. */ 1754 if (flush != Z_NO_FLUSH && flush != Z_FINISH && 1755 s->strm->avail_in == 0 && (long)s->strstart == s->block_start) 1756 return block_done; 1757 1758 /* Fill the window with any remaining input. */ 1759 have = s->window_size - s->strstart; 1760 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) { 1761 /* Slide the window down. */ 1762 s->block_start -= s->w_size; 1763 s->strstart -= s->w_size; 1764 zmemcpy(s->window, s->window + s->w_size, s->strstart); 1765 if (s->matches < 2) 1766 s->matches++; /* add a pending slide_hash() */ 1767 have += s->w_size; /* more space now */ 1768 if (s->insert > s->strstart) 1769 s->insert = s->strstart; 1770 } 1771 if (have > s->strm->avail_in) 1772 have = s->strm->avail_in; 1773 if (have) { 1774 read_buf(s->strm, s->window + s->strstart, have); 1775 s->strstart += have; 1776 s->insert += MIN(have, s->w_size - s->insert); 1777 } 1778 if (s->high_water < s->strstart) 1779 s->high_water = s->strstart; 1780 1781 /* There was not enough avail_out to write a complete worthy or flushed 1782 * stored block to next_out. Write a stored block to pending instead, if we 1783 * have enough input for a worthy block, or if flushing and there is enough 1784 * room for the remaining input as a stored block in the pending buffer. 1785 */ 1786 have = (s->bi_valid + 42) >> 3; /* number of header bytes */ 1787 /* maximum stored block length that will fit in pending: */ 1788 have = MIN(s->pending_buf_size - have, MAX_STORED); 1789 min_block = MIN(have, s->w_size); 1790 left = s->strstart - s->block_start; 1791 if (left >= min_block || 1792 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH && 1793 s->strm->avail_in == 0 && left <= have)) { 1794 len = MIN(left, have); 1795 last = flush == Z_FINISH && s->strm->avail_in == 0 && 1796 len == left ? 1 : 0; 1797 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last); 1798 s->block_start += len; 1799 flush_pending(s->strm); 1800 } 1801 1802 /* We've done all we can with the available input and output. */ 1803 return last ? finish_started : need_more; 1804 } 1805 1806 /* =========================================================================== 1807 * Compress as much as possible from the input stream, return the current 1808 * block state. 1809 * This function does not perform lazy evaluation of matches and inserts 1810 * new strings in the dictionary only for unmatched strings or for short 1811 * matches. It is used only for the fast compression options. 1812 */ 1813 local block_state deflate_fast(deflate_state *s, int flush) { 1814 IPos hash_head; /* head of the hash chain */ 1815 int bflush; /* set if current block must be flushed */ 1816 1817 for (;;) { 1818 /* Make sure that we always have enough lookahead, except 1819 * at the end of the input file. We need MAX_MATCH bytes 1820 * for the next match, plus MIN_MATCH bytes to insert the 1821 * string following the next match. 1822 */ 1823 if (s->lookahead < MIN_LOOKAHEAD) { 1824 fill_window(s); 1825 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1826 return need_more; 1827 } 1828 if (s->lookahead == 0) break; /* flush the current block */ 1829 } 1830 1831 /* Insert the string window[strstart .. strstart + 2] in the 1832 * dictionary, and set hash_head to the head of the hash chain: 1833 */ 1834 hash_head = NIL; 1835 if (s->lookahead >= MIN_MATCH) { 1836 INSERT_STRING(s, s->strstart, hash_head); 1837 } 1838 1839 /* Find the longest match, discarding those <= prev_length. 1840 * At this point we have always match_length < MIN_MATCH 1841 */ 1842 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1843 /* To simplify the code, we prevent matches with the string 1844 * of window index 0 (in particular we have to avoid a match 1845 * of the string with itself at the start of the input file). 1846 */ 1847 s->match_length = longest_match (s, hash_head); 1848 /* longest_match() sets match_start */ 1849 } 1850 if (s->match_length >= MIN_MATCH) { 1851 check_match(s, s->strstart, s->match_start, s->match_length); 1852 1853 _tr_tally_dist(s, s->strstart - s->match_start, 1854 s->match_length - MIN_MATCH, bflush); 1855 1856 s->lookahead -= s->match_length; 1857 1858 /* Insert new strings in the hash table only if the match length 1859 * is not too large. This saves time but degrades compression. 1860 */ 1861 #ifndef FASTEST 1862 if (s->match_length <= s->max_insert_length && 1863 s->lookahead >= MIN_MATCH) { 1864 s->match_length--; /* string at strstart already in table */ 1865 do { 1866 s->strstart++; 1867 INSERT_STRING(s, s->strstart, hash_head); 1868 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1869 * always MIN_MATCH bytes ahead. 1870 */ 1871 } while (--s->match_length != 0); 1872 s->strstart++; 1873 } else 1874 #endif 1875 { 1876 s->strstart += s->match_length; 1877 s->match_length = 0; 1878 s->ins_h = s->window[s->strstart]; 1879 UPDATE_HASH(s, s->ins_h, s->window[s->strstart + 1]); 1880 #if MIN_MATCH != 3 1881 Call UPDATE_HASH() MIN_MATCH-3 more times 1882 #endif 1883 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1884 * matter since it will be recomputed at next deflate call. 1885 */ 1886 } 1887 } else { 1888 /* No match, output a literal byte */ 1889 Tracevv((stderr,"%c", s->window[s->strstart])); 1890 _tr_tally_lit(s, s->window[s->strstart], bflush); 1891 s->lookahead--; 1892 s->strstart++; 1893 } 1894 if (bflush) FLUSH_BLOCK(s, 0); 1895 } 1896 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 1897 if (flush == Z_FINISH) { 1898 FLUSH_BLOCK(s, 1); 1899 return finish_done; 1900 } 1901 if (s->sym_next) 1902 FLUSH_BLOCK(s, 0); 1903 return block_done; 1904 } 1905 1906 #ifndef FASTEST 1907 /* =========================================================================== 1908 * Same as above, but achieves better compression. We use a lazy 1909 * evaluation for matches: a match is finally adopted only if there is 1910 * no better match at the next window position. 1911 */ 1912 local block_state deflate_slow(deflate_state *s, int flush) { 1913 IPos hash_head; /* head of hash chain */ 1914 int bflush; /* set if current block must be flushed */ 1915 1916 /* Process the input block. */ 1917 for (;;) { 1918 /* Make sure that we always have enough lookahead, except 1919 * at the end of the input file. We need MAX_MATCH bytes 1920 * for the next match, plus MIN_MATCH bytes to insert the 1921 * string following the next match. 1922 */ 1923 if (s->lookahead < MIN_LOOKAHEAD) { 1924 fill_window(s); 1925 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1926 return need_more; 1927 } 1928 if (s->lookahead == 0) break; /* flush the current block */ 1929 } 1930 1931 /* Insert the string window[strstart .. strstart + 2] in the 1932 * dictionary, and set hash_head to the head of the hash chain: 1933 */ 1934 hash_head = NIL; 1935 if (s->lookahead >= MIN_MATCH) { 1936 INSERT_STRING(s, s->strstart, hash_head); 1937 } 1938 1939 /* Find the longest match, discarding those <= prev_length. 1940 */ 1941 s->prev_length = s->match_length, s->prev_match = s->match_start; 1942 s->match_length = MIN_MATCH-1; 1943 1944 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1945 s->strstart - hash_head <= MAX_DIST(s)) { 1946 /* To simplify the code, we prevent matches with the string 1947 * of window index 0 (in particular we have to avoid a match 1948 * of the string with itself at the start of the input file). 1949 */ 1950 s->match_length = longest_match (s, hash_head); 1951 /* longest_match() sets match_start */ 1952 1953 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1954 #if TOO_FAR <= 32767 1955 || (s->match_length == MIN_MATCH && 1956 s->strstart - s->match_start > TOO_FAR) 1957 #endif 1958 )) { 1959 1960 /* If prev_match is also MIN_MATCH, match_start is garbage 1961 * but we will ignore the current match anyway. 1962 */ 1963 s->match_length = MIN_MATCH-1; 1964 } 1965 } 1966 /* If there was a match at the previous step and the current 1967 * match is not better, output the previous match: 1968 */ 1969 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1970 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1971 /* Do not insert strings in hash table beyond this. */ 1972 1973 check_match(s, s->strstart - 1, s->prev_match, s->prev_length); 1974 1975 _tr_tally_dist(s, s->strstart - 1 - s->prev_match, 1976 s->prev_length - MIN_MATCH, bflush); 1977 1978 /* Insert in hash table all strings up to the end of the match. 1979 * strstart - 1 and strstart are already inserted. If there is not 1980 * enough lookahead, the last two strings are not inserted in 1981 * the hash table. 1982 */ 1983 s->lookahead -= s->prev_length - 1; 1984 s->prev_length -= 2; 1985 do { 1986 if (++s->strstart <= max_insert) { 1987 INSERT_STRING(s, s->strstart, hash_head); 1988 } 1989 } while (--s->prev_length != 0); 1990 s->match_available = 0; 1991 s->match_length = MIN_MATCH-1; 1992 s->strstart++; 1993 1994 if (bflush) FLUSH_BLOCK(s, 0); 1995 1996 } else if (s->match_available) { 1997 /* If there was no match at the previous position, output a 1998 * single literal. If there was a match but the current match 1999 * is longer, truncate the previous match to a single literal. 2000 */ 2001 Tracevv((stderr,"%c", s->window[s->strstart - 1])); 2002 _tr_tally_lit(s, s->window[s->strstart - 1], bflush); 2003 if (bflush) { 2004 FLUSH_BLOCK_ONLY(s, 0); 2005 } 2006 s->strstart++; 2007 s->lookahead--; 2008 if (s->strm->avail_out == 0) return need_more; 2009 } else { 2010 /* There is no previous match to compare with, wait for 2011 * the next step to decide. 2012 */ 2013 s->match_available = 1; 2014 s->strstart++; 2015 s->lookahead--; 2016 } 2017 } 2018 Assert (flush != Z_NO_FLUSH, "no flush?"); 2019 if (s->match_available) { 2020 Tracevv((stderr,"%c", s->window[s->strstart - 1])); 2021 _tr_tally_lit(s, s->window[s->strstart - 1], bflush); 2022 s->match_available = 0; 2023 } 2024 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1; 2025 if (flush == Z_FINISH) { 2026 FLUSH_BLOCK(s, 1); 2027 return finish_done; 2028 } 2029 if (s->sym_next) 2030 FLUSH_BLOCK(s, 0); 2031 return block_done; 2032 } 2033 #endif /* FASTEST */ 2034 2035 /* =========================================================================== 2036 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 2037 * one. Do not maintain a hash table. (It will be regenerated if this run of 2038 * deflate switches away from Z_RLE.) 2039 */ 2040 local block_state deflate_rle(deflate_state *s, int flush) { 2041 int bflush; /* set if current block must be flushed */ 2042 uInt prev; /* byte at distance one to match */ 2043 Bytef *scan, *strend; /* scan goes up to strend for length of run */ 2044 2045 for (;;) { 2046 /* Make sure that we always have enough lookahead, except 2047 * at the end of the input file. We need MAX_MATCH bytes 2048 * for the longest run, plus one for the unrolled loop. 2049 */ 2050 if (s->lookahead <= MAX_MATCH) { 2051 fill_window(s); 2052 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) { 2053 return need_more; 2054 } 2055 if (s->lookahead == 0) break; /* flush the current block */ 2056 } 2057 2058 /* See how many times the previous byte repeats */ 2059 s->match_length = 0; 2060 if (s->lookahead >= MIN_MATCH && s->strstart > 0) { 2061 scan = s->window + s->strstart - 1; 2062 prev = *scan; 2063 if (prev == *++scan && prev == *++scan && prev == *++scan) { 2064 strend = s->window + s->strstart + MAX_MATCH; 2065 do { 2066 } while (prev == *++scan && prev == *++scan && 2067 prev == *++scan && prev == *++scan && 2068 prev == *++scan && prev == *++scan && 2069 prev == *++scan && prev == *++scan && 2070 scan < strend); 2071 s->match_length = MAX_MATCH - (uInt)(strend - scan); 2072 if (s->match_length > s->lookahead) 2073 s->match_length = s->lookahead; 2074 } 2075 Assert(scan <= s->window + (uInt)(s->window_size - 1), 2076 "wild scan"); 2077 } 2078 2079 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 2080 if (s->match_length >= MIN_MATCH) { 2081 check_match(s, s->strstart, s->strstart - 1, s->match_length); 2082 2083 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush); 2084 2085 s->lookahead -= s->match_length; 2086 s->strstart += s->match_length; 2087 s->match_length = 0; 2088 } else { 2089 /* No match, output a literal byte */ 2090 Tracevv((stderr,"%c", s->window[s->strstart])); 2091 _tr_tally_lit(s, s->window[s->strstart], bflush); 2092 s->lookahead--; 2093 s->strstart++; 2094 } 2095 if (bflush) FLUSH_BLOCK(s, 0); 2096 } 2097 s->insert = 0; 2098 if (flush == Z_FINISH) { 2099 FLUSH_BLOCK(s, 1); 2100 return finish_done; 2101 } 2102 if (s->sym_next) 2103 FLUSH_BLOCK(s, 0); 2104 return block_done; 2105 } 2106 2107 /* =========================================================================== 2108 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. 2109 * (It will be regenerated if this run of deflate switches away from Huffman.) 2110 */ 2111 local block_state deflate_huff(deflate_state *s, int flush) { 2112 int bflush; /* set if current block must be flushed */ 2113 2114 for (;;) { 2115 /* Make sure that we have a literal to write. */ 2116 if (s->lookahead == 0) { 2117 fill_window(s); 2118 if (s->lookahead == 0) { 2119 if (flush == Z_NO_FLUSH) 2120 return need_more; 2121 break; /* flush the current block */ 2122 } 2123 } 2124 2125 /* Output a literal byte */ 2126 s->match_length = 0; 2127 Tracevv((stderr,"%c", s->window[s->strstart])); 2128 _tr_tally_lit(s, s->window[s->strstart], bflush); 2129 s->lookahead--; 2130 s->strstart++; 2131 if (bflush) FLUSH_BLOCK(s, 0); 2132 } 2133 s->insert = 0; 2134 if (flush == Z_FINISH) { 2135 FLUSH_BLOCK(s, 1); 2136 return finish_done; 2137 } 2138 if (s->sym_next) 2139 FLUSH_BLOCK(s, 0); 2140 return block_done; 2141 } 2142