1 /* deflate.c -- compress data using the deflation algorithm 2 * Copyright (C) 1995-2005 Jean-loup Gailly. 3 * For conditions of distribution and use, see copyright notice in zlib.h 4 */ 5 6 /* 7 * ALGORITHM 8 * 9 * The "deflation" process depends on being able to identify portions 10 * of the input text which are identical to earlier input (within a 11 * sliding window trailing behind the input currently being processed). 12 * 13 * The most straightforward technique turns out to be the fastest for 14 * most input files: try all possible matches and select the longest. 15 * The key feature of this algorithm is that insertions into the string 16 * dictionary are very simple and thus fast, and deletions are avoided 17 * completely. Insertions are performed at each input character, whereas 18 * string matches are performed only when the previous match ends. So it 19 * is preferable to spend more time in matches to allow very fast string 20 * insertions and avoid deletions. The matching algorithm for small 21 * strings is inspired from that of Rabin & Karp. A brute force approach 22 * is used to find longer strings when a small match has been found. 23 * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze 24 * (by Leonid Broukhis). 25 * A previous version of this file used a more sophisticated algorithm 26 * (by Fiala and Greene) which is guaranteed to run in linear amortized 27 * time, but has a larger average cost, uses more memory and is patented. 28 * However the F&G algorithm may be faster for some highly redundant 29 * files if the parameter max_chain_length (described below) is too large. 30 * 31 * ACKNOWLEDGEMENTS 32 * 33 * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and 34 * I found it in 'freeze' written by Leonid Broukhis. 35 * Thanks to many people for bug reports and testing. 36 * 37 * REFERENCES 38 * 39 * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification". 40 * Available in http://www.ietf.org/rfc/rfc1951.txt 41 * 42 * A description of the Rabin and Karp algorithm is given in the book 43 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252. 44 * 45 * Fiala,E.R., and Greene,D.H. 46 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595 47 * 48 */ 49 50 /* @(#) $Id$ */ 51 52 #include "deflate.h" 53 54 const char deflate_copyright[] = 55 " deflate 1.2.3 Copyright 1995-2005 Jean-loup Gailly "; 56 /* 57 If you use the zlib library in a product, an acknowledgment is welcome 58 in the documentation of your product. If for some reason you cannot 59 include such an acknowledgment, I would appreciate that you keep this 60 copyright string in the executable of your product. 61 */ 62 63 /* =========================================================================== 64 * Function prototypes. 65 */ 66 typedef enum { 67 need_more, /* block not completed, need more input or more output */ 68 block_done, /* block flush performed */ 69 finish_started, /* finish started, need only more output at next deflate */ 70 finish_done /* finish done, accept no more input or output */ 71 } block_state; 72 73 typedef block_state (*compress_func) OF((deflate_state *s, int flush)); 74 /* Compression function. Returns the block state after the call. */ 75 76 local void fill_window OF((deflate_state *s)); 77 local block_state deflate_stored OF((deflate_state *s, int flush)); 78 local block_state deflate_fast OF((deflate_state *s, int flush)); 79 #ifndef FASTEST 80 local block_state deflate_slow OF((deflate_state *s, int flush)); 81 #endif 82 local void lm_init OF((deflate_state *s)); 83 local void putShortMSB OF((deflate_state *s, uInt b)); 84 local void flush_pending OF((z_streamp strm)); 85 local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size)); 86 #ifndef FASTEST 87 #ifdef ASMV 88 void match_init OF((void)); /* asm code initialization */ 89 uInt longest_match OF((deflate_state *s, IPos cur_match)); 90 #else 91 local uInt longest_match OF((deflate_state *s, IPos cur_match)); 92 #endif 93 #endif 94 local uInt longest_match_fast OF((deflate_state *s, IPos cur_match)); 95 96 #ifdef DEBUG 97 local void check_match OF((deflate_state *s, IPos start, IPos match, 98 int length)); 99 #endif 100 101 /* =========================================================================== 102 * Local data 103 */ 104 105 #define NIL 0 106 /* Tail of hash chains */ 107 108 #ifndef TOO_FAR 109 # define TOO_FAR 4096 110 #endif 111 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ 112 113 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) 114 /* Minimum amount of lookahead, except at the end of the input file. 115 * See deflate.c for comments about the MIN_MATCH+1. 116 */ 117 118 /* Values for max_lazy_match, good_match and max_chain_length, depending on 119 * the desired pack level (0..9). The values given below have been tuned to 120 * exclude worst case performance for pathological files. Better values may be 121 * found for specific files. 122 */ 123 typedef struct config_s { 124 ush good_length; /* reduce lazy search above this match length */ 125 ush max_lazy; /* do not perform lazy search above this match length */ 126 ush nice_length; /* quit search above this match length */ 127 ush max_chain; 128 compress_func func; 129 } config; 130 131 #ifdef FASTEST 132 local const config configuration_table[2] = { 133 /* good lazy nice chain */ 134 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 135 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ 136 #else 137 local const config configuration_table[10] = { 138 /* good lazy nice chain */ 139 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ 140 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ 141 /* 2 */ {4, 5, 16, 8, deflate_fast}, 142 /* 3 */ {4, 6, 32, 32, deflate_fast}, 143 144 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ 145 /* 5 */ {8, 16, 32, 32, deflate_slow}, 146 /* 6 */ {8, 16, 128, 128, deflate_slow}, 147 /* 7 */ {8, 32, 128, 256, deflate_slow}, 148 /* 8 */ {32, 128, 258, 1024, deflate_slow}, 149 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ 150 #endif 151 152 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 153 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different 154 * meaning. 155 */ 156 157 #define EQUAL 0 158 /* result of memcmp for equal strings */ 159 160 #ifndef NO_DUMMY_DECL 161 struct static_tree_desc_s {int dummy;}; /* for buggy compilers */ 162 #endif 163 164 /* =========================================================================== 165 * Update a hash value with the given input byte 166 * IN assertion: all calls to to UPDATE_HASH are made with consecutive 167 * input characters, so that a running hash key can be computed from the 168 * previous key instead of complete recalculation each time. 169 */ 170 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask) 171 172 173 /* =========================================================================== 174 * Insert string str in the dictionary and set match_head to the previous head 175 * of the hash chain (the most recent string with same hash key). Return 176 * the previous length of the hash chain. 177 * If this file is compiled with -DFASTEST, the compression level is forced 178 * to 1, and no hash chains are maintained. 179 * IN assertion: all calls to to INSERT_STRING are made with consecutive 180 * input characters and the first MIN_MATCH bytes of str are valid 181 * (except for the last MIN_MATCH-1 bytes of the input file). 182 */ 183 #ifdef FASTEST 184 #define INSERT_STRING(s, str, match_head) \ 185 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 186 match_head = s->head[s->ins_h], \ 187 s->head[s->ins_h] = (Pos)(str)) 188 #else 189 #define INSERT_STRING(s, str, match_head) \ 190 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ 191 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ 192 s->head[s->ins_h] = (Pos)(str)) 193 #endif 194 195 /* =========================================================================== 196 * Initialize the hash table (avoiding 64K overflow for 16 bit systems). 197 * prev[] will be initialized on the fly. 198 */ 199 #define CLEAR_HASH(s) \ 200 s->head[s->hash_size-1] = NIL; \ 201 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head)); 202 203 /* ========================================================================= */ 204 int ZEXPORT deflateInit_(strm, level, version, stream_size) 205 z_streamp strm; 206 int level; 207 const char *version; 208 int stream_size; 209 { 210 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, 211 Z_DEFAULT_STRATEGY, version, stream_size); 212 /* To do: ignore strm->next_in if we use it as window */ 213 } 214 215 /* ========================================================================= */ 216 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy, 217 version, stream_size) 218 z_streamp strm; 219 int level; 220 int method; 221 int windowBits; 222 int memLevel; 223 int strategy; 224 const char *version; 225 int stream_size; 226 { 227 deflate_state *s; 228 int wrap = 1; 229 static const char my_version[] = ZLIB_VERSION; 230 231 ushf *overlay; 232 /* We overlay pending_buf and d_buf+l_buf. This works since the average 233 * output size for (length,distance) codes is <= 24 bits. 234 */ 235 236 if (version == Z_NULL || version[0] != my_version[0] || 237 stream_size != sizeof(z_stream)) { 238 return Z_VERSION_ERROR; 239 } 240 if (strm == Z_NULL) return Z_STREAM_ERROR; 241 242 strm->msg = Z_NULL; 243 if (strm->zalloc == (alloc_func)0) { 244 strm->zalloc = zcalloc; 245 strm->opaque = (voidpf)0; 246 } 247 if (strm->zfree == (free_func)0) strm->zfree = zcfree; 248 249 #ifdef FASTEST 250 if (level != 0) level = 1; 251 #else 252 if (level == Z_DEFAULT_COMPRESSION) level = 6; 253 #endif 254 255 if (windowBits < 0) { /* suppress zlib wrapper */ 256 wrap = 0; 257 windowBits = -windowBits; 258 } 259 #ifdef GZIP 260 else if (windowBits > 15) { 261 wrap = 2; /* write gzip wrapper instead */ 262 windowBits -= 16; 263 } 264 #endif 265 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || 266 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || 267 strategy < 0 || strategy > Z_FIXED) { 268 return Z_STREAM_ERROR; 269 } 270 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 271 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 272 if (s == Z_NULL) return Z_MEM_ERROR; 273 strm->state = (struct internal_state FAR *)s; 274 s->strm = strm; 275 276 s->wrap = wrap; 277 s->gzhead = Z_NULL; 278 s->w_bits = windowBits; 279 s->w_size = 1 << s->w_bits; 280 s->w_mask = s->w_size - 1; 281 282 s->hash_bits = memLevel + 7; 283 s->hash_size = 1 << s->hash_bits; 284 s->hash_mask = s->hash_size - 1; 285 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); 286 287 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 288 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 289 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 290 291 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 292 293 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); 294 s->pending_buf = (uchf *) overlay; 295 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); 296 297 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || 298 s->pending_buf == Z_NULL) { 299 s->status = FINISH_STATE; 300 strm->msg = (char*)ERR_MSG(Z_MEM_ERROR); 301 deflateEnd (strm); 302 return Z_MEM_ERROR; 303 } 304 s->d_buf = overlay + s->lit_bufsize/sizeof(ush); 305 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; 306 307 s->level = level; 308 s->strategy = strategy; 309 s->method = (Byte)method; 310 311 return deflateReset(strm); 312 } 313 314 /* ========================================================================= */ 315 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength) 316 z_streamp strm; 317 const Bytef *dictionary; 318 uInt dictLength; 319 { 320 deflate_state *s; 321 uInt length = dictLength; 322 uInt n; 323 IPos hash_head = 0; 324 325 if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL || 326 strm->state->wrap == 2 || 327 (strm->state->wrap == 1 && strm->state->status != INIT_STATE)) 328 return Z_STREAM_ERROR; 329 330 s = strm->state; 331 if (s->wrap) 332 strm->adler = adler32(strm->adler, dictionary, dictLength); 333 334 if (length < MIN_MATCH) return Z_OK; 335 if (length > MAX_DIST(s)) { 336 length = MAX_DIST(s); 337 dictionary += dictLength - length; /* use the tail of the dictionary */ 338 } 339 zmemcpy(s->window, dictionary, length); 340 s->strstart = length; 341 s->block_start = (long)length; 342 343 /* Insert all strings in the hash table (except for the last two bytes). 344 * s->lookahead stays null, so s->ins_h will be recomputed at the next 345 * call of fill_window. 346 */ 347 s->ins_h = s->window[0]; 348 UPDATE_HASH(s, s->ins_h, s->window[1]); 349 for (n = 0; n <= length - MIN_MATCH; n++) { 350 INSERT_STRING(s, n, hash_head); 351 } 352 if (hash_head) hash_head = 0; /* to make compiler happy */ 353 return Z_OK; 354 } 355 356 /* ========================================================================= */ 357 int ZEXPORT deflateReset (strm) 358 z_streamp strm; 359 { 360 deflate_state *s; 361 362 if (strm == Z_NULL || strm->state == Z_NULL || 363 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) { 364 return Z_STREAM_ERROR; 365 } 366 367 strm->total_in = strm->total_out = 0; 368 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 369 strm->data_type = Z_UNKNOWN; 370 371 s = (deflate_state *)strm->state; 372 s->pending = 0; 373 s->pending_out = s->pending_buf; 374 375 if (s->wrap < 0) { 376 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ 377 } 378 s->status = s->wrap ? INIT_STATE : BUSY_STATE; 379 strm->adler = 380 #ifdef GZIP 381 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : 382 #endif 383 adler32(0L, Z_NULL, 0); 384 s->last_flush = Z_NO_FLUSH; 385 386 _tr_init(s); 387 lm_init(s); 388 389 return Z_OK; 390 } 391 392 /* ========================================================================= */ 393 int ZEXPORT deflateSetHeader (strm, head) 394 z_streamp strm; 395 gz_headerp head; 396 { 397 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 398 if (strm->state->wrap != 2) return Z_STREAM_ERROR; 399 strm->state->gzhead = head; 400 return Z_OK; 401 } 402 403 /* ========================================================================= */ 404 int ZEXPORT deflatePrime (strm, bits, value) 405 z_streamp strm; 406 int bits; 407 int value; 408 { 409 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 410 strm->state->bi_valid = bits; 411 strm->state->bi_buf = (ush)(value & ((1 << bits) - 1)); 412 return Z_OK; 413 } 414 415 /* ========================================================================= */ 416 int ZEXPORT deflateParams(strm, level, strategy) 417 z_streamp strm; 418 int level; 419 int strategy; 420 { 421 deflate_state *s; 422 compress_func func; 423 int err = Z_OK; 424 425 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 426 s = strm->state; 427 428 #ifdef FASTEST 429 if (level != 0) level = 1; 430 #else 431 if (level == Z_DEFAULT_COMPRESSION) level = 6; 432 #endif 433 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { 434 return Z_STREAM_ERROR; 435 } 436 func = configuration_table[s->level].func; 437 438 if (func != configuration_table[level].func && strm->total_in != 0) { 439 /* Flush the last buffer: */ 440 err = deflate(strm, Z_PARTIAL_FLUSH); 441 } 442 if (s->level != level) { 443 s->level = level; 444 s->max_lazy_match = configuration_table[level].max_lazy; 445 s->good_match = configuration_table[level].good_length; 446 s->nice_match = configuration_table[level].nice_length; 447 s->max_chain_length = configuration_table[level].max_chain; 448 } 449 s->strategy = strategy; 450 return err; 451 } 452 453 /* ========================================================================= */ 454 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain) 455 z_streamp strm; 456 int good_length; 457 int max_lazy; 458 int nice_length; 459 int max_chain; 460 { 461 deflate_state *s; 462 463 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 464 s = strm->state; 465 s->good_match = good_length; 466 s->max_lazy_match = max_lazy; 467 s->nice_match = nice_length; 468 s->max_chain_length = max_chain; 469 return Z_OK; 470 } 471 472 /* ========================================================================= 473 * For the default windowBits of 15 and memLevel of 8, this function returns 474 * a close to exact, as well as small, upper bound on the compressed size. 475 * They are coded as constants here for a reason--if the #define's are 476 * changed, then this function needs to be changed as well. The return 477 * value for 15 and 8 only works for those exact settings. 478 * 479 * For any setting other than those defaults for windowBits and memLevel, 480 * the value returned is a conservative worst case for the maximum expansion 481 * resulting from using fixed blocks instead of stored blocks, which deflate 482 * can emit on compressed data for some combinations of the parameters. 483 * 484 * This function could be more sophisticated to provide closer upper bounds 485 * for every combination of windowBits and memLevel, as well as wrap. 486 * But even the conservative upper bound of about 14% expansion does not 487 * seem onerous for output buffer allocation. 488 */ 489 uLong ZEXPORT deflateBound(strm, sourceLen) 490 z_streamp strm; 491 uLong sourceLen; 492 { 493 deflate_state *s; 494 uLong destLen; 495 496 /* conservative upper bound */ 497 destLen = sourceLen + 498 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11; 499 500 /* if can't get parameters, return conservative bound */ 501 if (strm == Z_NULL || strm->state == Z_NULL) 502 return destLen; 503 504 /* if not default parameters, return conservative bound */ 505 s = strm->state; 506 if (s->w_bits != 15 || s->hash_bits != 8 + 7) 507 return destLen; 508 509 /* default settings: return tight bound for that case */ 510 return compressBound(sourceLen); 511 } 512 513 /* ========================================================================= 514 * Put a short in the pending buffer. The 16-bit value is put in MSB order. 515 * IN assertion: the stream state is correct and there is enough room in 516 * pending_buf. 517 */ 518 local void putShortMSB (s, b) 519 deflate_state *s; 520 uInt b; 521 { 522 put_byte(s, (Byte)(b >> 8)); 523 put_byte(s, (Byte)(b & 0xff)); 524 } 525 526 /* ========================================================================= 527 * Flush as much pending output as possible. All deflate() output goes 528 * through this function so some applications may wish to modify it 529 * to avoid allocating a large strm->next_out buffer and copying into it. 530 * (See also read_buf()). 531 */ 532 local void flush_pending(strm) 533 z_streamp strm; 534 { 535 unsigned len = strm->state->pending; 536 537 if (len > strm->avail_out) len = strm->avail_out; 538 if (len == 0) return; 539 540 zmemcpy(strm->next_out, strm->state->pending_out, len); 541 strm->next_out += len; 542 strm->state->pending_out += len; 543 strm->total_out += len; 544 strm->avail_out -= len; 545 strm->state->pending -= len; 546 if (strm->state->pending == 0) { 547 strm->state->pending_out = strm->state->pending_buf; 548 } 549 } 550 551 /* ========================================================================= */ 552 int ZEXPORT deflate (strm, flush) 553 z_streamp strm; 554 int flush; 555 { 556 int old_flush; /* value of flush param for previous deflate call */ 557 deflate_state *s; 558 559 if (strm == Z_NULL || strm->state == Z_NULL || 560 flush > Z_FINISH || flush < 0) { 561 return Z_STREAM_ERROR; 562 } 563 s = strm->state; 564 565 if (strm->next_out == Z_NULL || 566 (strm->next_in == Z_NULL && strm->avail_in != 0) || 567 (s->status == FINISH_STATE && flush != Z_FINISH)) { 568 ERR_RETURN(strm, Z_STREAM_ERROR); 569 } 570 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 571 572 s->strm = strm; /* just in case */ 573 old_flush = s->last_flush; 574 s->last_flush = flush; 575 576 /* Write the header */ 577 if (s->status == INIT_STATE) { 578 #ifdef GZIP 579 if (s->wrap == 2) { 580 strm->adler = crc32(0L, Z_NULL, 0); 581 put_byte(s, 31); 582 put_byte(s, 139); 583 put_byte(s, 8); 584 if (s->gzhead == NULL) { 585 put_byte(s, 0); 586 put_byte(s, 0); 587 put_byte(s, 0); 588 put_byte(s, 0); 589 put_byte(s, 0); 590 put_byte(s, s->level == 9 ? 2 : 591 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 592 4 : 0)); 593 put_byte(s, OS_CODE); 594 s->status = BUSY_STATE; 595 } 596 else { 597 put_byte(s, (s->gzhead->text ? 1 : 0) + 598 (s->gzhead->hcrc ? 2 : 0) + 599 (s->gzhead->extra == Z_NULL ? 0 : 4) + 600 (s->gzhead->name == Z_NULL ? 0 : 8) + 601 (s->gzhead->comment == Z_NULL ? 0 : 16) 602 ); 603 put_byte(s, (Byte)(s->gzhead->time & 0xff)); 604 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); 605 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); 606 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); 607 put_byte(s, s->level == 9 ? 2 : 608 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? 609 4 : 0)); 610 put_byte(s, s->gzhead->os & 0xff); 611 if (s->gzhead->extra != NULL) { 612 put_byte(s, s->gzhead->extra_len & 0xff); 613 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); 614 } 615 if (s->gzhead->hcrc) 616 strm->adler = crc32(strm->adler, s->pending_buf, 617 s->pending); 618 s->gzindex = 0; 619 s->status = EXTRA_STATE; 620 } 621 } 622 else 623 #endif 624 { 625 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; 626 uInt level_flags; 627 628 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) 629 level_flags = 0; 630 else if (s->level < 6) 631 level_flags = 1; 632 else if (s->level == 6) 633 level_flags = 2; 634 else 635 level_flags = 3; 636 header |= (level_flags << 6); 637 if (s->strstart != 0) header |= PRESET_DICT; 638 header += 31 - (header % 31); 639 640 s->status = BUSY_STATE; 641 putShortMSB(s, header); 642 643 /* Save the adler32 of the preset dictionary: */ 644 if (s->strstart != 0) { 645 putShortMSB(s, (uInt)(strm->adler >> 16)); 646 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 647 } 648 strm->adler = adler32(0L, Z_NULL, 0); 649 } 650 } 651 #ifdef GZIP 652 if (s->status == EXTRA_STATE) { 653 if (s->gzhead->extra != NULL) { 654 uInt beg = s->pending; /* start of bytes to update crc */ 655 656 while (s->gzindex < (s->gzhead->extra_len & 0xffff)) { 657 if (s->pending == s->pending_buf_size) { 658 if (s->gzhead->hcrc && s->pending > beg) 659 strm->adler = crc32(strm->adler, s->pending_buf + beg, 660 s->pending - beg); 661 flush_pending(strm); 662 beg = s->pending; 663 if (s->pending == s->pending_buf_size) 664 break; 665 } 666 put_byte(s, s->gzhead->extra[s->gzindex]); 667 s->gzindex++; 668 } 669 if (s->gzhead->hcrc && s->pending > beg) 670 strm->adler = crc32(strm->adler, s->pending_buf + beg, 671 s->pending - beg); 672 if (s->gzindex == s->gzhead->extra_len) { 673 s->gzindex = 0; 674 s->status = NAME_STATE; 675 } 676 } 677 else 678 s->status = NAME_STATE; 679 } 680 if (s->status == NAME_STATE) { 681 if (s->gzhead->name != NULL) { 682 uInt beg = s->pending; /* start of bytes to update crc */ 683 int val; 684 685 do { 686 if (s->pending == s->pending_buf_size) { 687 if (s->gzhead->hcrc && s->pending > beg) 688 strm->adler = crc32(strm->adler, s->pending_buf + beg, 689 s->pending - beg); 690 flush_pending(strm); 691 beg = s->pending; 692 if (s->pending == s->pending_buf_size) { 693 val = 1; 694 break; 695 } 696 } 697 val = s->gzhead->name[s->gzindex++]; 698 put_byte(s, val); 699 } while (val != 0); 700 if (s->gzhead->hcrc && s->pending > beg) 701 strm->adler = crc32(strm->adler, s->pending_buf + beg, 702 s->pending - beg); 703 if (val == 0) { 704 s->gzindex = 0; 705 s->status = COMMENT_STATE; 706 } 707 } 708 else 709 s->status = COMMENT_STATE; 710 } 711 if (s->status == COMMENT_STATE) { 712 if (s->gzhead->comment != NULL) { 713 uInt beg = s->pending; /* start of bytes to update crc */ 714 int val; 715 716 do { 717 if (s->pending == s->pending_buf_size) { 718 if (s->gzhead->hcrc && s->pending > beg) 719 strm->adler = crc32(strm->adler, s->pending_buf + beg, 720 s->pending - beg); 721 flush_pending(strm); 722 beg = s->pending; 723 if (s->pending == s->pending_buf_size) { 724 val = 1; 725 break; 726 } 727 } 728 val = s->gzhead->comment[s->gzindex++]; 729 put_byte(s, val); 730 } while (val != 0); 731 if (s->gzhead->hcrc && s->pending > beg) 732 strm->adler = crc32(strm->adler, s->pending_buf + beg, 733 s->pending - beg); 734 if (val == 0) 735 s->status = HCRC_STATE; 736 } 737 else 738 s->status = HCRC_STATE; 739 } 740 if (s->status == HCRC_STATE) { 741 if (s->gzhead->hcrc) { 742 if (s->pending + 2 > s->pending_buf_size) 743 flush_pending(strm); 744 if (s->pending + 2 <= s->pending_buf_size) { 745 put_byte(s, (Byte)(strm->adler & 0xff)); 746 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 747 strm->adler = crc32(0L, Z_NULL, 0); 748 s->status = BUSY_STATE; 749 } 750 } 751 else 752 s->status = BUSY_STATE; 753 } 754 #endif 755 756 /* Flush as much pending output as possible */ 757 if (s->pending != 0) { 758 flush_pending(strm); 759 if (strm->avail_out == 0) { 760 /* Since avail_out is 0, deflate will be called again with 761 * more output space, but possibly with both pending and 762 * avail_in equal to zero. There won't be anything to do, 763 * but this is not an error situation so make sure we 764 * return OK instead of BUF_ERROR at next call of deflate: 765 */ 766 s->last_flush = -1; 767 return Z_OK; 768 } 769 770 /* Make sure there is something to do and avoid duplicate consecutive 771 * flushes. For repeated and useless calls with Z_FINISH, we keep 772 * returning Z_STREAM_END instead of Z_BUF_ERROR. 773 */ 774 } else if (strm->avail_in == 0 && flush <= old_flush && 775 flush != Z_FINISH) { 776 ERR_RETURN(strm, Z_BUF_ERROR); 777 } 778 779 /* User must not provide more input after the first FINISH: */ 780 if (s->status == FINISH_STATE && strm->avail_in != 0) { 781 ERR_RETURN(strm, Z_BUF_ERROR); 782 } 783 784 /* Start a new block or continue the current one. 785 */ 786 if (strm->avail_in != 0 || s->lookahead != 0 || 787 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 788 block_state bstate; 789 790 bstate = (*(configuration_table[s->level].func))(s, flush); 791 792 if (bstate == finish_started || bstate == finish_done) { 793 s->status = FINISH_STATE; 794 } 795 if (bstate == need_more || bstate == finish_started) { 796 if (strm->avail_out == 0) { 797 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ 798 } 799 return Z_OK; 800 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call 801 * of deflate should use the same flush parameter to make sure 802 * that the flush is complete. So we don't have to output an 803 * empty block here, this will be done at next call. This also 804 * ensures that for a very small output buffer, we emit at most 805 * one empty block. 806 */ 807 } 808 if (bstate == block_done) { 809 if (flush == Z_PARTIAL_FLUSH) { 810 _tr_align(s); 811 } else { /* FULL_FLUSH or SYNC_FLUSH */ 812 _tr_stored_block(s, (char*)0, 0L, 0); 813 /* For a full flush, this empty block will be recognized 814 * as a special marker by inflate_sync(). 815 */ 816 if (flush == Z_FULL_FLUSH) { 817 CLEAR_HASH(s); /* forget history */ 818 } 819 } 820 flush_pending(strm); 821 if (strm->avail_out == 0) { 822 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ 823 return Z_OK; 824 } 825 } 826 } 827 Assert(strm->avail_out > 0, "bug2"); 828 829 if (flush != Z_FINISH) return Z_OK; 830 if (s->wrap <= 0) return Z_STREAM_END; 831 832 /* Write the trailer */ 833 #ifdef GZIP 834 if (s->wrap == 2) { 835 put_byte(s, (Byte)(strm->adler & 0xff)); 836 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); 837 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); 838 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); 839 put_byte(s, (Byte)(strm->total_in & 0xff)); 840 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); 841 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); 842 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); 843 } 844 else 845 #endif 846 { 847 putShortMSB(s, (uInt)(strm->adler >> 16)); 848 putShortMSB(s, (uInt)(strm->adler & 0xffff)); 849 } 850 flush_pending(strm); 851 /* If avail_out is zero, the application will call deflate again 852 * to flush the rest. 853 */ 854 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 855 return s->pending != 0 ? Z_OK : Z_STREAM_END; 856 } 857 858 /* ========================================================================= */ 859 int ZEXPORT deflateEnd (strm) 860 z_streamp strm; 861 { 862 int status; 863 864 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 865 866 status = strm->state->status; 867 if (status != INIT_STATE && 868 status != EXTRA_STATE && 869 status != NAME_STATE && 870 status != COMMENT_STATE && 871 status != HCRC_STATE && 872 status != BUSY_STATE && 873 status != FINISH_STATE) { 874 return Z_STREAM_ERROR; 875 } 876 877 /* Deallocate in reverse order of allocations: */ 878 TRY_FREE(strm, strm->state->pending_buf); 879 TRY_FREE(strm, strm->state->head); 880 TRY_FREE(strm, strm->state->prev); 881 TRY_FREE(strm, strm->state->window); 882 883 ZFREE(strm, strm->state); 884 strm->state = Z_NULL; 885 886 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; 887 } 888 889 /* ========================================================================= 890 * Copy the source state to the destination state. 891 * To simplify the source, this is not supported for 16-bit MSDOS (which 892 * doesn't have enough memory anyway to duplicate compression states). 893 */ 894 int ZEXPORT deflateCopy (dest, source) 895 z_streamp dest; 896 z_streamp source; 897 { 898 #ifdef MAXSEG_64K 899 return Z_STREAM_ERROR; 900 #else 901 deflate_state *ds; 902 deflate_state *ss; 903 ushf *overlay; 904 905 906 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) { 907 return Z_STREAM_ERROR; 908 } 909 910 ss = source->state; 911 912 zmemcpy(dest, source, sizeof(z_stream)); 913 914 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); 915 if (ds == Z_NULL) return Z_MEM_ERROR; 916 dest->state = (struct internal_state FAR *) ds; 917 zmemcpy(ds, ss, sizeof(deflate_state)); 918 ds->strm = dest; 919 920 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); 921 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); 922 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); 923 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); 924 ds->pending_buf = (uchf *) overlay; 925 926 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || 927 ds->pending_buf == Z_NULL) { 928 deflateEnd (dest); 929 return Z_MEM_ERROR; 930 } 931 /* following zmemcpy do not work for 16-bit MSDOS */ 932 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); 933 zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos)); 934 zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos)); 935 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); 936 937 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); 938 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); 939 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; 940 941 ds->l_desc.dyn_tree = ds->dyn_ltree; 942 ds->d_desc.dyn_tree = ds->dyn_dtree; 943 ds->bl_desc.dyn_tree = ds->bl_tree; 944 945 return Z_OK; 946 #endif /* MAXSEG_64K */ 947 } 948 949 /* =========================================================================== 950 * Read a new buffer from the current input stream, update the adler32 951 * and total number of bytes read. All deflate() input goes through 952 * this function so some applications may wish to modify it to avoid 953 * allocating a large strm->next_in buffer and copying from it. 954 * (See also flush_pending()). 955 */ 956 local int read_buf(strm, buf, size) 957 z_streamp strm; 958 Bytef *buf; 959 unsigned size; 960 { 961 unsigned len = strm->avail_in; 962 963 if (len > size) len = size; 964 if (len == 0) return 0; 965 966 strm->avail_in -= len; 967 968 if (strm->state->wrap == 1) { 969 strm->adler = adler32(strm->adler, strm->next_in, len); 970 } 971 #ifdef GZIP 972 else if (strm->state->wrap == 2) { 973 strm->adler = crc32(strm->adler, strm->next_in, len); 974 } 975 #endif 976 zmemcpy(buf, strm->next_in, len); 977 strm->next_in += len; 978 strm->total_in += len; 979 980 return (int)len; 981 } 982 983 /* =========================================================================== 984 * Initialize the "longest match" routines for a new zlib stream 985 */ 986 local void lm_init (s) 987 deflate_state *s; 988 { 989 s->window_size = (ulg)2L*s->w_size; 990 991 CLEAR_HASH(s); 992 993 /* Set the default configuration parameters: 994 */ 995 s->max_lazy_match = configuration_table[s->level].max_lazy; 996 s->good_match = configuration_table[s->level].good_length; 997 s->nice_match = configuration_table[s->level].nice_length; 998 s->max_chain_length = configuration_table[s->level].max_chain; 999 1000 s->strstart = 0; 1001 s->block_start = 0L; 1002 s->lookahead = 0; 1003 s->match_length = s->prev_length = MIN_MATCH-1; 1004 s->match_available = 0; 1005 s->ins_h = 0; 1006 #ifndef FASTEST 1007 #ifdef ASMV 1008 match_init(); /* initialize the asm code */ 1009 #endif 1010 #endif 1011 } 1012 1013 #ifndef FASTEST 1014 /* =========================================================================== 1015 * Set match_start to the longest match starting at the given string and 1016 * return its length. Matches shorter or equal to prev_length are discarded, 1017 * in which case the result is equal to prev_length and match_start is 1018 * garbage. 1019 * IN assertions: cur_match is the head of the hash chain for the current 1020 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 1021 * OUT assertion: the match length is not greater than s->lookahead. 1022 */ 1023 #ifndef ASMV 1024 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or 1025 * match.S. The code will be functionally equivalent. 1026 */ 1027 local uInt longest_match(s, cur_match) 1028 deflate_state *s; 1029 IPos cur_match; /* current match */ 1030 { 1031 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 1032 register Bytef *scan = s->window + s->strstart; /* current string */ 1033 register Bytef *match; /* matched string */ 1034 register int len; /* length of current match */ 1035 int best_len = s->prev_length; /* best match length so far */ 1036 int nice_match = s->nice_match; /* stop if match long enough */ 1037 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 1038 s->strstart - (IPos)MAX_DIST(s) : NIL; 1039 /* Stop when cur_match becomes <= limit. To simplify the code, 1040 * we prevent matches with the string of window index 0. 1041 */ 1042 Posf *prev = s->prev; 1043 uInt wmask = s->w_mask; 1044 1045 #ifdef UNALIGNED_OK 1046 /* Compare two bytes at a time. Note: this is not always beneficial. 1047 * Try with and without -DUNALIGNED_OK to check. 1048 */ 1049 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; 1050 register ush scan_start = *(ushf*)scan; 1051 register ush scan_end = *(ushf*)(scan+best_len-1); 1052 #else 1053 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1054 register Byte scan_end1 = scan[best_len-1]; 1055 register Byte scan_end = scan[best_len]; 1056 #endif 1057 1058 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1059 * It is easy to get rid of this optimization if necessary. 1060 */ 1061 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1062 1063 /* Do not waste too much time if we already have a good match: */ 1064 if (s->prev_length >= s->good_match) { 1065 chain_length >>= 2; 1066 } 1067 /* Do not look for matches beyond the end of the input. This is necessary 1068 * to make deflate deterministic. 1069 */ 1070 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; 1071 1072 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1073 1074 do { 1075 Assert(cur_match < s->strstart, "no future"); 1076 match = s->window + cur_match; 1077 1078 /* Skip to next match if the match length cannot increase 1079 * or if the match length is less than 2. Note that the checks below 1080 * for insufficient lookahead only occur occasionally for performance 1081 * reasons. Therefore uninitialized memory will be accessed, and 1082 * conditional jumps will be made that depend on those values. 1083 * However the length of the match is limited to the lookahead, so 1084 * the output of deflate is not affected by the uninitialized values. 1085 */ 1086 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) 1087 /* This code assumes sizeof(unsigned short) == 2. Do not use 1088 * UNALIGNED_OK if your compiler uses a different size. 1089 */ 1090 if (*(ushf*)(match+best_len-1) != scan_end || 1091 *(ushf*)match != scan_start) continue; 1092 1093 /* It is not necessary to compare scan[2] and match[2] since they are 1094 * always equal when the other bytes match, given that the hash keys 1095 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at 1096 * strstart+3, +5, ... up to strstart+257. We check for insufficient 1097 * lookahead only every 4th comparison; the 128th check will be made 1098 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is 1099 * necessary to put more guard bytes at the end of the window, or 1100 * to check more often for insufficient lookahead. 1101 */ 1102 Assert(scan[2] == match[2], "scan[2]?"); 1103 scan++, match++; 1104 do { 1105 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1106 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1107 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1108 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && 1109 scan < strend); 1110 /* The funny "do {}" generates better code on most compilers */ 1111 1112 /* Here, scan <= window+strstart+257 */ 1113 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1114 if (*scan == *match) scan++; 1115 1116 len = (MAX_MATCH - 1) - (int)(strend-scan); 1117 scan = strend - (MAX_MATCH-1); 1118 1119 #else /* UNALIGNED_OK */ 1120 1121 if (match[best_len] != scan_end || 1122 match[best_len-1] != scan_end1 || 1123 *match != *scan || 1124 *++match != scan[1]) continue; 1125 1126 /* The check at best_len-1 can be removed because it will be made 1127 * again later. (This heuristic is not always a win.) 1128 * It is not necessary to compare scan[2] and match[2] since they 1129 * are always equal when the other bytes match, given that 1130 * the hash keys are equal and that HASH_BITS >= 8. 1131 */ 1132 scan += 2, match++; 1133 Assert(*scan == *match, "match[2]?"); 1134 1135 /* We check for insufficient lookahead only every 8th comparison; 1136 * the 256th check will be made at strstart+258. 1137 */ 1138 do { 1139 } while (*++scan == *++match && *++scan == *++match && 1140 *++scan == *++match && *++scan == *++match && 1141 *++scan == *++match && *++scan == *++match && 1142 *++scan == *++match && *++scan == *++match && 1143 scan < strend); 1144 1145 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1146 1147 len = MAX_MATCH - (int)(strend - scan); 1148 scan = strend - MAX_MATCH; 1149 1150 #endif /* UNALIGNED_OK */ 1151 1152 if (len > best_len) { 1153 s->match_start = cur_match; 1154 best_len = len; 1155 if (len >= nice_match) break; 1156 #ifdef UNALIGNED_OK 1157 scan_end = *(ushf*)(scan+best_len-1); 1158 #else 1159 scan_end1 = scan[best_len-1]; 1160 scan_end = scan[best_len]; 1161 #endif 1162 } 1163 } while ((cur_match = prev[cur_match & wmask]) > limit 1164 && --chain_length != 0); 1165 1166 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 1167 return s->lookahead; 1168 } 1169 #endif /* ASMV */ 1170 #endif /* FASTEST */ 1171 1172 /* --------------------------------------------------------------------------- 1173 * Optimized version for level == 1 or strategy == Z_RLE only 1174 */ 1175 local uInt longest_match_fast(s, cur_match) 1176 deflate_state *s; 1177 IPos cur_match; /* current match */ 1178 { 1179 register Bytef *scan = s->window + s->strstart; /* current string */ 1180 register Bytef *match; /* matched string */ 1181 register int len; /* length of current match */ 1182 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 1183 1184 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. 1185 * It is easy to get rid of this optimization if necessary. 1186 */ 1187 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); 1188 1189 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 1190 1191 Assert(cur_match < s->strstart, "no future"); 1192 1193 match = s->window + cur_match; 1194 1195 /* Return failure if the match length is less than 2: 1196 */ 1197 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; 1198 1199 /* The check at best_len-1 can be removed because it will be made 1200 * again later. (This heuristic is not always a win.) 1201 * It is not necessary to compare scan[2] and match[2] since they 1202 * are always equal when the other bytes match, given that 1203 * the hash keys are equal and that HASH_BITS >= 8. 1204 */ 1205 scan += 2, match += 2; 1206 Assert(*scan == *match, "match[2]?"); 1207 1208 /* We check for insufficient lookahead only every 8th comparison; 1209 * the 256th check will be made at strstart+258. 1210 */ 1211 do { 1212 } while (*++scan == *++match && *++scan == *++match && 1213 *++scan == *++match && *++scan == *++match && 1214 *++scan == *++match && *++scan == *++match && 1215 *++scan == *++match && *++scan == *++match && 1216 scan < strend); 1217 1218 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); 1219 1220 len = MAX_MATCH - (int)(strend - scan); 1221 1222 if (len < MIN_MATCH) return MIN_MATCH - 1; 1223 1224 s->match_start = cur_match; 1225 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; 1226 } 1227 1228 #ifdef DEBUG 1229 /* =========================================================================== 1230 * Check that the match at match_start is indeed a match. 1231 */ 1232 local void check_match(s, start, match, length) 1233 deflate_state *s; 1234 IPos start, match; 1235 int length; 1236 { 1237 /* check that the match is indeed a match */ 1238 if (zmemcmp(s->window + match, 1239 s->window + start, length) != EQUAL) { 1240 fprintf(stderr, " start %u, match %u, length %d\n", 1241 start, match, length); 1242 do { 1243 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); 1244 } while (--length != 0); 1245 z_error("invalid match"); 1246 } 1247 if (z_verbose > 1) { 1248 fprintf(stderr,"\\[%d,%d]", start-match, length); 1249 do { putc(s->window[start++], stderr); } while (--length != 0); 1250 } 1251 } 1252 #else 1253 # define check_match(s, start, match, length) 1254 #endif /* DEBUG */ 1255 1256 /* =========================================================================== 1257 * Fill the window when the lookahead becomes insufficient. 1258 * Updates strstart and lookahead. 1259 * 1260 * IN assertion: lookahead < MIN_LOOKAHEAD 1261 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD 1262 * At least one byte has been read, or avail_in == 0; reads are 1263 * performed for at least two bytes (required for the zip translate_eol 1264 * option -- not supported here). 1265 */ 1266 local void fill_window(s) 1267 deflate_state *s; 1268 { 1269 register unsigned n, m; 1270 register Posf *p; 1271 unsigned more; /* Amount of free space at the end of the window. */ 1272 uInt wsize = s->w_size; 1273 1274 do { 1275 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); 1276 1277 /* Deal with !@#$% 64K limit: */ 1278 if (sizeof(int) <= 2) { 1279 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 1280 more = wsize; 1281 1282 } else if (more == (unsigned)(-1)) { 1283 /* Very unlikely, but possible on 16 bit machine if 1284 * strstart == 0 && lookahead == 1 (input done a byte at time) 1285 */ 1286 more--; 1287 } 1288 } 1289 1290 /* If the window is almost full and there is insufficient lookahead, 1291 * move the upper half to the lower one to make room in the upper half. 1292 */ 1293 if (s->strstart >= wsize+MAX_DIST(s)) { 1294 1295 zmemcpy(s->window, s->window+wsize, (unsigned)wsize); 1296 s->match_start -= wsize; 1297 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 1298 s->block_start -= (long) wsize; 1299 1300 /* Slide the hash table (could be avoided with 32 bit values 1301 at the expense of memory usage). We slide even when level == 0 1302 to keep the hash table consistent if we switch back to level > 0 1303 later. (Using level 0 permanently is not an optimal usage of 1304 zlib, so we don't care about this pathological case.) 1305 */ 1306 /* %%% avoid this when Z_RLE */ 1307 n = s->hash_size; 1308 p = &s->head[n]; 1309 do { 1310 m = *--p; 1311 *p = (Pos)(m >= wsize ? m-wsize : NIL); 1312 } while (--n); 1313 1314 n = wsize; 1315 #ifndef FASTEST 1316 p = &s->prev[n]; 1317 do { 1318 m = *--p; 1319 *p = (Pos)(m >= wsize ? m-wsize : NIL); 1320 /* If n is not on any hash chain, prev[n] is garbage but 1321 * its value will never be used. 1322 */ 1323 } while (--n); 1324 #endif 1325 more += wsize; 1326 } 1327 if (s->strm->avail_in == 0) return; 1328 1329 /* If there was no sliding: 1330 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && 1331 * more == window_size - lookahead - strstart 1332 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) 1333 * => more >= window_size - 2*WSIZE + 2 1334 * In the BIG_MEM or MMAP case (not yet supported), 1335 * window_size == input_size + MIN_LOOKAHEAD && 1336 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. 1337 * Otherwise, window_size == 2*WSIZE so more >= 2. 1338 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. 1339 */ 1340 Assert(more >= 2, "more < 2"); 1341 1342 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 1343 s->lookahead += n; 1344 1345 /* Initialize the hash value now that we have some input: */ 1346 if (s->lookahead >= MIN_MATCH) { 1347 s->ins_h = s->window[s->strstart]; 1348 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); 1349 #if MIN_MATCH != 3 1350 Call UPDATE_HASH() MIN_MATCH-3 more times 1351 #endif 1352 } 1353 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, 1354 * but this is not important since only literal bytes will be emitted. 1355 */ 1356 1357 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); 1358 } 1359 1360 /* =========================================================================== 1361 * Flush the current block, with given end-of-file flag. 1362 * IN assertion: strstart is set to the end of the current match. 1363 */ 1364 #define FLUSH_BLOCK_ONLY(s, eof) { \ 1365 _tr_flush_block(s, (s->block_start >= 0L ? \ 1366 (charf *)&s->window[(unsigned)s->block_start] : \ 1367 (charf *)Z_NULL), \ 1368 (ulg)((long)s->strstart - s->block_start), \ 1369 (eof)); \ 1370 s->block_start = s->strstart; \ 1371 flush_pending(s->strm); \ 1372 Tracev((stderr,"[FLUSH]")); \ 1373 } 1374 1375 /* Same but force premature exit if necessary. */ 1376 #define FLUSH_BLOCK(s, eof) { \ 1377 FLUSH_BLOCK_ONLY(s, eof); \ 1378 if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \ 1379 } 1380 1381 /* =========================================================================== 1382 * Copy without compression as much as possible from the input stream, return 1383 * the current block state. 1384 * This function does not insert new strings in the dictionary since 1385 * uncompressible data is probably not useful. This function is used 1386 * only for the level=0 compression option. 1387 * NOTE: this function should be optimized to avoid extra copying from 1388 * window to pending_buf. 1389 */ 1390 local block_state deflate_stored(s, flush) 1391 deflate_state *s; 1392 int flush; 1393 { 1394 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited 1395 * to pending_buf_size, and each stored block has a 5 byte header: 1396 */ 1397 ulg max_block_size = 0xffff; 1398 ulg max_start; 1399 1400 if (max_block_size > s->pending_buf_size - 5) { 1401 max_block_size = s->pending_buf_size - 5; 1402 } 1403 1404 /* Copy as much as possible from input to output: */ 1405 for (;;) { 1406 /* Fill the window as much as possible: */ 1407 if (s->lookahead <= 1) { 1408 1409 Assert(s->strstart < s->w_size+MAX_DIST(s) || 1410 s->block_start >= (long)s->w_size, "slide too late"); 1411 1412 fill_window(s); 1413 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more; 1414 1415 if (s->lookahead == 0) break; /* flush the current block */ 1416 } 1417 Assert(s->block_start >= 0L, "block gone"); 1418 1419 s->strstart += s->lookahead; 1420 s->lookahead = 0; 1421 1422 /* Emit a stored block if pending_buf will be full: */ 1423 max_start = s->block_start + max_block_size; 1424 if (s->strstart == 0 || (ulg)s->strstart >= max_start) { 1425 /* strstart == 0 is possible when wraparound on 16-bit machine */ 1426 s->lookahead = (uInt)(s->strstart - max_start); 1427 s->strstart = (uInt)max_start; 1428 FLUSH_BLOCK(s, 0); 1429 } 1430 /* Flush if we may have to slide, otherwise block_start may become 1431 * negative and the data will be gone: 1432 */ 1433 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) { 1434 FLUSH_BLOCK(s, 0); 1435 } 1436 } 1437 FLUSH_BLOCK(s, flush == Z_FINISH); 1438 return flush == Z_FINISH ? finish_done : block_done; 1439 } 1440 1441 /* =========================================================================== 1442 * Compress as much as possible from the input stream, return the current 1443 * block state. 1444 * This function does not perform lazy evaluation of matches and inserts 1445 * new strings in the dictionary only for unmatched strings or for short 1446 * matches. It is used only for the fast compression options. 1447 */ 1448 local block_state deflate_fast(s, flush) 1449 deflate_state *s; 1450 int flush; 1451 { 1452 IPos hash_head = NIL; /* head of the hash chain */ 1453 int bflush; /* set if current block must be flushed */ 1454 1455 for (;;) { 1456 /* Make sure that we always have enough lookahead, except 1457 * at the end of the input file. We need MAX_MATCH bytes 1458 * for the next match, plus MIN_MATCH bytes to insert the 1459 * string following the next match. 1460 */ 1461 if (s->lookahead < MIN_LOOKAHEAD) { 1462 fill_window(s); 1463 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1464 return need_more; 1465 } 1466 if (s->lookahead == 0) break; /* flush the current block */ 1467 } 1468 1469 /* Insert the string window[strstart .. strstart+2] in the 1470 * dictionary, and set hash_head to the head of the hash chain: 1471 */ 1472 if (s->lookahead >= MIN_MATCH) { 1473 INSERT_STRING(s, s->strstart, hash_head); 1474 } 1475 1476 /* Find the longest match, discarding those <= prev_length. 1477 * At this point we have always match_length < MIN_MATCH 1478 */ 1479 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { 1480 /* To simplify the code, we prevent matches with the string 1481 * of window index 0 (in particular we have to avoid a match 1482 * of the string with itself at the start of the input file). 1483 */ 1484 #ifdef FASTEST 1485 if ((s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) || 1486 (s->strategy == Z_RLE && s->strstart - hash_head == 1)) { 1487 s->match_length = longest_match_fast (s, hash_head); 1488 } 1489 #else 1490 if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) { 1491 s->match_length = longest_match (s, hash_head); 1492 } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) { 1493 s->match_length = longest_match_fast (s, hash_head); 1494 } 1495 #endif 1496 /* longest_match() or longest_match_fast() sets match_start */ 1497 } 1498 if (s->match_length >= MIN_MATCH) { 1499 check_match(s, s->strstart, s->match_start, s->match_length); 1500 1501 _tr_tally_dist(s, s->strstart - s->match_start, 1502 s->match_length - MIN_MATCH, bflush); 1503 1504 s->lookahead -= s->match_length; 1505 1506 /* Insert new strings in the hash table only if the match length 1507 * is not too large. This saves time but degrades compression. 1508 */ 1509 #ifndef FASTEST 1510 if (s->match_length <= s->max_insert_length && 1511 s->lookahead >= MIN_MATCH) { 1512 s->match_length--; /* string at strstart already in table */ 1513 do { 1514 s->strstart++; 1515 INSERT_STRING(s, s->strstart, hash_head); 1516 /* strstart never exceeds WSIZE-MAX_MATCH, so there are 1517 * always MIN_MATCH bytes ahead. 1518 */ 1519 } while (--s->match_length != 0); 1520 s->strstart++; 1521 } else 1522 #endif 1523 { 1524 s->strstart += s->match_length; 1525 s->match_length = 0; 1526 s->ins_h = s->window[s->strstart]; 1527 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); 1528 #if MIN_MATCH != 3 1529 Call UPDATE_HASH() MIN_MATCH-3 more times 1530 #endif 1531 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not 1532 * matter since it will be recomputed at next deflate call. 1533 */ 1534 } 1535 } else { 1536 /* No match, output a literal byte */ 1537 Tracevv((stderr,"%c", s->window[s->strstart])); 1538 _tr_tally_lit (s, s->window[s->strstart], bflush); 1539 s->lookahead--; 1540 s->strstart++; 1541 } 1542 if (bflush) FLUSH_BLOCK(s, 0); 1543 } 1544 FLUSH_BLOCK(s, flush == Z_FINISH); 1545 return flush == Z_FINISH ? finish_done : block_done; 1546 } 1547 1548 #ifndef FASTEST 1549 /* =========================================================================== 1550 * Same as above, but achieves better compression. We use a lazy 1551 * evaluation for matches: a match is finally adopted only if there is 1552 * no better match at the next window position. 1553 */ 1554 local block_state deflate_slow(s, flush) 1555 deflate_state *s; 1556 int flush; 1557 { 1558 IPos hash_head = NIL; /* head of hash chain */ 1559 int bflush; /* set if current block must be flushed */ 1560 1561 /* Process the input block. */ 1562 for (;;) { 1563 /* Make sure that we always have enough lookahead, except 1564 * at the end of the input file. We need MAX_MATCH bytes 1565 * for the next match, plus MIN_MATCH bytes to insert the 1566 * string following the next match. 1567 */ 1568 if (s->lookahead < MIN_LOOKAHEAD) { 1569 fill_window(s); 1570 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 1571 return need_more; 1572 } 1573 if (s->lookahead == 0) break; /* flush the current block */ 1574 } 1575 1576 /* Insert the string window[strstart .. strstart+2] in the 1577 * dictionary, and set hash_head to the head of the hash chain: 1578 */ 1579 if (s->lookahead >= MIN_MATCH) { 1580 INSERT_STRING(s, s->strstart, hash_head); 1581 } 1582 1583 /* Find the longest match, discarding those <= prev_length. 1584 */ 1585 s->prev_length = s->match_length, s->prev_match = s->match_start; 1586 s->match_length = MIN_MATCH-1; 1587 1588 if (hash_head != NIL && s->prev_length < s->max_lazy_match && 1589 s->strstart - hash_head <= MAX_DIST(s)) { 1590 /* To simplify the code, we prevent matches with the string 1591 * of window index 0 (in particular we have to avoid a match 1592 * of the string with itself at the start of the input file). 1593 */ 1594 if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) { 1595 s->match_length = longest_match (s, hash_head); 1596 } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) { 1597 s->match_length = longest_match_fast (s, hash_head); 1598 } 1599 /* longest_match() or longest_match_fast() sets match_start */ 1600 1601 if (s->match_length <= 5 && (s->strategy == Z_FILTERED 1602 #if TOO_FAR <= 32767 1603 || (s->match_length == MIN_MATCH && 1604 s->strstart - s->match_start > TOO_FAR) 1605 #endif 1606 )) { 1607 1608 /* If prev_match is also MIN_MATCH, match_start is garbage 1609 * but we will ignore the current match anyway. 1610 */ 1611 s->match_length = MIN_MATCH-1; 1612 } 1613 } 1614 /* If there was a match at the previous step and the current 1615 * match is not better, output the previous match: 1616 */ 1617 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 1618 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; 1619 /* Do not insert strings in hash table beyond this. */ 1620 1621 check_match(s, s->strstart-1, s->prev_match, s->prev_length); 1622 1623 _tr_tally_dist(s, s->strstart -1 - s->prev_match, 1624 s->prev_length - MIN_MATCH, bflush); 1625 1626 /* Insert in hash table all strings up to the end of the match. 1627 * strstart-1 and strstart are already inserted. If there is not 1628 * enough lookahead, the last two strings are not inserted in 1629 * the hash table. 1630 */ 1631 s->lookahead -= s->prev_length-1; 1632 s->prev_length -= 2; 1633 do { 1634 if (++s->strstart <= max_insert) { 1635 INSERT_STRING(s, s->strstart, hash_head); 1636 } 1637 } while (--s->prev_length != 0); 1638 s->match_available = 0; 1639 s->match_length = MIN_MATCH-1; 1640 s->strstart++; 1641 1642 if (bflush) FLUSH_BLOCK(s, 0); 1643 1644 } else if (s->match_available) { 1645 /* If there was no match at the previous position, output a 1646 * single literal. If there was a match but the current match 1647 * is longer, truncate the previous match to a single literal. 1648 */ 1649 Tracevv((stderr,"%c", s->window[s->strstart-1])); 1650 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 1651 if (bflush) { 1652 FLUSH_BLOCK_ONLY(s, 0); 1653 } 1654 s->strstart++; 1655 s->lookahead--; 1656 if (s->strm->avail_out == 0) return need_more; 1657 } else { 1658 /* There is no previous match to compare with, wait for 1659 * the next step to decide. 1660 */ 1661 s->match_available = 1; 1662 s->strstart++; 1663 s->lookahead--; 1664 } 1665 } 1666 Assert (flush != Z_NO_FLUSH, "no flush?"); 1667 if (s->match_available) { 1668 Tracevv((stderr,"%c", s->window[s->strstart-1])); 1669 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 1670 s->match_available = 0; 1671 } 1672 FLUSH_BLOCK(s, flush == Z_FINISH); 1673 return flush == Z_FINISH ? finish_done : block_done; 1674 } 1675 #endif /* FASTEST */ 1676 1677 #if 0 1678 /* =========================================================================== 1679 * For Z_RLE, simply look for runs of bytes, generate matches only of distance 1680 * one. Do not maintain a hash table. (It will be regenerated if this run of 1681 * deflate switches away from Z_RLE.) 1682 */ 1683 local block_state deflate_rle(s, flush) 1684 deflate_state *s; 1685 int flush; 1686 { 1687 int bflush; /* set if current block must be flushed */ 1688 uInt run; /* length of run */ 1689 uInt max; /* maximum length of run */ 1690 uInt prev; /* byte at distance one to match */ 1691 Bytef *scan; /* scan for end of run */ 1692 1693 for (;;) { 1694 /* Make sure that we always have enough lookahead, except 1695 * at the end of the input file. We need MAX_MATCH bytes 1696 * for the longest encodable run. 1697 */ 1698 if (s->lookahead < MAX_MATCH) { 1699 fill_window(s); 1700 if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) { 1701 return need_more; 1702 } 1703 if (s->lookahead == 0) break; /* flush the current block */ 1704 } 1705 1706 /* See how many times the previous byte repeats */ 1707 run = 0; 1708 if (s->strstart > 0) { /* if there is a previous byte, that is */ 1709 max = s->lookahead < MAX_MATCH ? s->lookahead : MAX_MATCH; 1710 scan = s->window + s->strstart - 1; 1711 prev = *scan++; 1712 do { 1713 if (*scan++ != prev) 1714 break; 1715 } while (++run < max); 1716 } 1717 1718 /* Emit match if have run of MIN_MATCH or longer, else emit literal */ 1719 if (run >= MIN_MATCH) { 1720 check_match(s, s->strstart, s->strstart - 1, run); 1721 _tr_tally_dist(s, 1, run - MIN_MATCH, bflush); 1722 s->lookahead -= run; 1723 s->strstart += run; 1724 } else { 1725 /* No match, output a literal byte */ 1726 Tracevv((stderr,"%c", s->window[s->strstart])); 1727 _tr_tally_lit (s, s->window[s->strstart], bflush); 1728 s->lookahead--; 1729 s->strstart++; 1730 } 1731 if (bflush) FLUSH_BLOCK(s, 0); 1732 } 1733 FLUSH_BLOCK(s, flush == Z_FINISH); 1734 return flush == Z_FINISH ? finish_done : block_done; 1735 } 1736 #endif 1737
