trees.c
1 /* trees.c -- output deflated data using Huffman coding 2 * Copyright (C) 1995-2017 Jean-loup Gailly 3 * detect_data_type() function provided freely by Cosmin Truta, 2006 4 * For conditions of distribution and use, see copyright notice in zlib.h 5 */ 6 7 /* 8 * ALGORITHM 9 * 10 * The "deflation" process uses several Huffman trees. The more 11 * common source values are represented by shorter bit sequences. 12 * 13 * Each code tree is stored in a compressed form which is itself 14 * a Huffman encoding of the lengths of all the code strings (in 15 * ascending order by source values). The actual code strings are 16 * reconstructed from the lengths in the inflate process, as described 17 * in the deflate specification. 18 * 19 * REFERENCES 20 * 21 * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification". 22 * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc 23 * 24 * Storer, James A. 25 * Data Compression: Methods and Theory, pp. 49-50. 26 * Computer Science Press, 1988. ISBN 0-7167-8156-5. 27 * 28 * Sedgewick, R. 29 * Algorithms, p290. 30 * Addison-Wesley, 1983. ISBN 0-201-06672-6. 31 */ 32 33 /* @(#) $Id$ */ 34 35 /* #define GEN_TREES_H */ 36 37 #include "deflate.h" 38 39 #ifdef ZLIB_DEBUG 40 # include <ctype.h> 41 #endif 42 43 /* =========================================================================== 44 * Constants 45 */ 46 47 #define MAX_BL_BITS 7 48 /* Bit length codes must not exceed MAX_BL_BITS bits */ 49 50 #define END_BLOCK 256 51 /* end of block literal code */ 52 53 #define REP_3_6 16 54 /* repeat previous bit length 3-6 times (2 bits of repeat count) */ 55 56 #define REPZ_3_10 17 57 /* repeat a zero length 3-10 times (3 bits of repeat count) */ 58 59 #define REPZ_11_138 18 60 /* repeat a zero length 11-138 times (7 bits of repeat count) */ 61 62 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ 63 = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0}; 64 65 local const int extra_dbits[D_CODES] /* extra bits for each distance code */ 66 = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13}; 67 68 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */ 69 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; 70 71 local const uch bl_order[BL_CODES] 72 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; 73 /* The lengths of the bit length codes are sent in order of decreasing 74 * probability, to avoid transmitting the lengths for unused bit length codes. 75 */ 76 77 /* =========================================================================== 78 * Local data. These are initialized only once. 79 */ 80 81 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */ 82 83 #if defined(GEN_TREES_H) || !defined(STDC) 84 /* non ANSI compilers may not accept trees.h */ 85 86 local ct_data static_ltree[L_CODES+2]; 87 /* The static literal tree. Since the bit lengths are imposed, there is no 88 * need for the L_CODES extra codes used during heap construction. However 89 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init 90 * below). 91 */ 92 93 local ct_data static_dtree[D_CODES]; 94 /* The static distance tree. (Actually a trivial tree since all codes use 95 * 5 bits.) 96 */ 97 98 uch _dist_code[DIST_CODE_LEN]; 99 /* Distance codes. The first 256 values correspond to the distances 100 * 3 .. 258, the last 256 values correspond to the top 8 bits of 101 * the 15 bit distances. 102 */ 103 104 uch _length_code[MAX_MATCH-MIN_MATCH+1]; 105 /* length code for each normalized match length (0 == MIN_MATCH) */ 106 107 local int base_length[LENGTH_CODES]; 108 /* First normalized length for each code (0 = MIN_MATCH) */ 109 110 local int base_dist[D_CODES]; 111 /* First normalized distance for each code (0 = distance of 1) */ 112 113 #else 114 # include "trees.h" 115 #endif /* GEN_TREES_H */ 116 117 struct static_tree_desc_s { 118 const ct_data *static_tree; /* static tree or NULL */ 119 const intf *extra_bits; /* extra bits for each code or NULL */ 120 int extra_base; /* base index for extra_bits */ 121 int elems; /* max number of elements in the tree */ 122 int max_length; /* max bit length for the codes */ 123 }; 124 125 local const static_tree_desc static_l_desc = 126 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; 127 128 local const static_tree_desc static_d_desc = 129 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; 130 131 local const static_tree_desc static_bl_desc = 132 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; 133 134 /* =========================================================================== 135 * Local (static) routines in this file. 136 */ 137 138 local void tr_static_init OF((void)); 139 local void init_block OF((deflate_state *s)); 140 local void pqdownheap OF((deflate_state *s, ct_data *tree, int k)); 141 local void gen_bitlen OF((deflate_state *s, tree_desc *desc)); 142 local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count)); 143 local void build_tree OF((deflate_state *s, tree_desc *desc)); 144 local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code)); 145 local void send_tree OF((deflate_state *s, ct_data *tree, int max_code)); 146 local int build_bl_tree OF((deflate_state *s)); 147 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes, 148 int blcodes)); 149 local void compress_block OF((deflate_state *s, const ct_data *ltree, 150 const ct_data *dtree)); 151 local int detect_data_type OF((deflate_state *s)); 152 local unsigned bi_reverse OF((unsigned value, int length)); 153 local void bi_windup OF((deflate_state *s)); 154 local void bi_flush OF((deflate_state *s)); 155 156 #ifdef GEN_TREES_H 157 local void gen_trees_header OF((void)); 158 #endif 159 160 #ifndef ZLIB_DEBUG 161 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len) 162 /* Send a code of the given tree. c and tree must not have side effects */ 163 164 #else /* !ZLIB_DEBUG */ 165 # define send_code(s, c, tree) \ 166 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \ 167 send_bits(s, tree[c].Code, tree[c].Len); } 168 #endif 169 170 /* =========================================================================== 171 * Output a short LSB first on the stream. 172 * IN assertion: there is enough room in pendingBuf. 173 */ 174 #define put_short(s, w) { \ 175 put_byte(s, (uch)((w) & 0xff)); \ 176 put_byte(s, (uch)((ush)(w) >> 8)); \ 177 } 178 179 /* =========================================================================== 180 * Send a value on a given number of bits. 181 * IN assertion: length <= 16 and value fits in length bits. 182 */ 183 #ifdef ZLIB_DEBUG 184 local void send_bits OF((deflate_state *s, int value, int length)); 185 186 local void send_bits(s, value, length) 187 deflate_state *s; 188 int value; /* value to send */ 189 int length; /* number of bits */ 190 { 191 Tracevv((stderr," l %2d v %4x ", length, value)); 192 Assert(length > 0 && length <= 15, "invalid length"); 193 s->bits_sent += (ulg)length; 194 195 /* If not enough room in bi_buf, use (valid) bits from bi_buf and 196 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid)) 197 * unused bits in value. 198 */ 199 if (s->bi_valid > (int)Buf_size - length) { 200 s->bi_buf |= (ush)value << s->bi_valid; 201 put_short(s, s->bi_buf); 202 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid); 203 s->bi_valid += length - Buf_size; 204 } else { 205 s->bi_buf |= (ush)value << s->bi_valid; 206 s->bi_valid += length; 207 } 208 } 209 #else /* !ZLIB_DEBUG */ 210 211 #define send_bits(s, value, length) \ 212 { int len = length;\ 213 if (s->bi_valid > (int)Buf_size - len) {\ 214 int val = (int)value;\ 215 s->bi_buf |= (ush)val << s->bi_valid;\ 216 put_short(s, s->bi_buf);\ 217 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\ 218 s->bi_valid += len - Buf_size;\ 219 } else {\ 220 s->bi_buf |= (ush)(value) << s->bi_valid;\ 221 s->bi_valid += len;\ 222 }\ 223 } 224 #endif /* ZLIB_DEBUG */ 225 226 227 /* the arguments must not have side effects */ 228 229 /* =========================================================================== 230 * Initialize the various 'constant' tables. 231 */ 232 local void tr_static_init() 233 { 234 #if defined(GEN_TREES_H) || !defined(STDC) 235 static int static_init_done = 0; 236 int n; /* iterates over tree elements */ 237 int bits; /* bit counter */ 238 int length; /* length value */ 239 int code; /* code value */ 240 int dist; /* distance index */ 241 ush bl_count[MAX_BITS+1]; 242 /* number of codes at each bit length for an optimal tree */ 243 244 if (static_init_done) return; 245 246 /* For some embedded targets, global variables are not initialized: */ 247 #ifdef NO_INIT_GLOBAL_POINTERS 248 static_l_desc.static_tree = static_ltree; 249 static_l_desc.extra_bits = extra_lbits; 250 static_d_desc.static_tree = static_dtree; 251 static_d_desc.extra_bits = extra_dbits; 252 static_bl_desc.extra_bits = extra_blbits; 253 #endif 254 255 /* Initialize the mapping length (0..255) -> length code (0..28) */ 256 length = 0; 257 for (code = 0; code < LENGTH_CODES-1; code++) { 258 base_length[code] = length; 259 for (n = 0; n < (1<<extra_lbits[code]); n++) { 260 _length_code[length++] = (uch)code; 261 } 262 } 263 Assert (length == 256, "tr_static_init: length != 256"); 264 /* Note that the length 255 (match length 258) can be represented 265 * in two different ways: code 284 + 5 bits or code 285, so we 266 * overwrite length_code[255] to use the best encoding: 267 */ 268 _length_code[length-1] = (uch)code; 269 270 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ 271 dist = 0; 272 for (code = 0 ; code < 16; code++) { 273 base_dist[code] = dist; 274 for (n = 0; n < (1<<extra_dbits[code]); n++) { 275 _dist_code[dist++] = (uch)code; 276 } 277 } 278 Assert (dist == 256, "tr_static_init: dist != 256"); 279 dist >>= 7; /* from now on, all distances are divided by 128 */ 280 for ( ; code < D_CODES; code++) { 281 base_dist[code] = dist << 7; 282 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { 283 _dist_code[256 + dist++] = (uch)code; 284 } 285 } 286 Assert (dist == 256, "tr_static_init: 256+dist != 512"); 287 288 /* Construct the codes of the static literal tree */ 289 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; 290 n = 0; 291 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; 292 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; 293 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; 294 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; 295 /* Codes 286 and 287 do not exist, but we must include them in the 296 * tree construction to get a canonical Huffman tree (longest code 297 * all ones) 298 */ 299 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count); 300 301 /* The static distance tree is trivial: */ 302 for (n = 0; n < D_CODES; n++) { 303 static_dtree[n].Len = 5; 304 static_dtree[n].Code = bi_reverse((unsigned)n, 5); 305 } 306 static_init_done = 1; 307 308 # ifdef GEN_TREES_H 309 gen_trees_header(); 310 # endif 311 #endif /* defined(GEN_TREES_H) || !defined(STDC) */ 312 } 313 314 /* =========================================================================== 315 * Genererate the file trees.h describing the static trees. 316 */ 317 #ifdef GEN_TREES_H 318 # ifndef ZLIB_DEBUG 319 # include <stdio.h> 320 # endif 321 322 # define SEPARATOR(i, last, width) \ 323 ((i) == (last)? "\n};\n\n" : \ 324 ((i) % (width) == (width)-1 ? ",\n" : ", ")) 325 326 void gen_trees_header() 327 { 328 FILE *header = fopen("trees.h", "w"); 329 int i; 330 331 Assert (header != NULL, "Can't open trees.h"); 332 fprintf(header, 333 "/* header created automatically with -DGEN_TREES_H */\n\n"); 334 335 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n"); 336 for (i = 0; i < L_CODES+2; i++) { 337 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code, 338 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5)); 339 } 340 341 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n"); 342 for (i = 0; i < D_CODES; i++) { 343 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code, 344 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5)); 345 } 346 347 fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n"); 348 for (i = 0; i < DIST_CODE_LEN; i++) { 349 fprintf(header, "%2u%s", _dist_code[i], 350 SEPARATOR(i, DIST_CODE_LEN-1, 20)); 351 } 352 353 fprintf(header, 354 "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n"); 355 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) { 356 fprintf(header, "%2u%s", _length_code[i], 357 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20)); 358 } 359 360 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n"); 361 for (i = 0; i < LENGTH_CODES; i++) { 362 fprintf(header, "%1u%s", base_length[i], 363 SEPARATOR(i, LENGTH_CODES-1, 20)); 364 } 365 366 fprintf(header, "local const int base_dist[D_CODES] = {\n"); 367 for (i = 0; i < D_CODES; i++) { 368 fprintf(header, "%5u%s", base_dist[i], 369 SEPARATOR(i, D_CODES-1, 10)); 370 } 371 372 fclose(header); 373 } 374 #endif /* GEN_TREES_H */ 375 376 /* =========================================================================== 377 * Initialize the tree data structures for a new zlib stream. 378 */ 379 void ZLIB_INTERNAL _tr_init(s) 380 deflate_state *s; 381 { 382 tr_static_init(); 383 384 s->l_desc.dyn_tree = s->dyn_ltree; 385 s->l_desc.stat_desc = &static_l_desc; 386 387 s->d_desc.dyn_tree = s->dyn_dtree; 388 s->d_desc.stat_desc = &static_d_desc; 389 390 s->bl_desc.dyn_tree = s->bl_tree; 391 s->bl_desc.stat_desc = &static_bl_desc; 392 393 s->bi_buf = 0; 394 s->bi_valid = 0; 395 #ifdef ZLIB_DEBUG 396 s->compressed_len = 0L; 397 s->bits_sent = 0L; 398 #endif 399 400 /* Initialize the first block of the first file: */ 401 init_block(s); 402 } 403 404 /* =========================================================================== 405 * Initialize a new block. 406 */ 407 local void init_block(s) 408 deflate_state *s; 409 { 410 int n; /* iterates over tree elements */ 411 412 /* Initialize the trees. */ 413 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0; 414 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0; 415 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0; 416 417 s->dyn_ltree[END_BLOCK].Freq = 1; 418 s->opt_len = s->static_len = 0L; 419 s->last_lit = s->matches = 0; 420 } 421 422 #define SMALLEST 1 423 /* Index within the heap array of least frequent node in the Huffman tree */ 424 425 426 /* =========================================================================== 427 * Remove the smallest element from the heap and recreate the heap with 428 * one less element. Updates heap and heap_len. 429 */ 430 #define pqremove(s, tree, top) \ 431 {\ 432 top = s->heap[SMALLEST]; \ 433 s->heap[SMALLEST] = s->heap[s->heap_len--]; \ 434 pqdownheap(s, tree, SMALLEST); \ 435 } 436 437 /* =========================================================================== 438 * Compares to subtrees, using the tree depth as tie breaker when 439 * the subtrees have equal frequency. This minimizes the worst case length. 440 */ 441 #define smaller(tree, n, m, depth) \ 442 (tree[n].Freq < tree[m].Freq || \ 443 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) 444 445 /* =========================================================================== 446 * Restore the heap property by moving down the tree starting at node k, 447 * exchanging a node with the smallest of its two sons if necessary, stopping 448 * when the heap property is re-established (each father smaller than its 449 * two sons). 450 */ 451 local void pqdownheap(s, tree, k) 452 deflate_state *s; 453 ct_data *tree; /* the tree to restore */ 454 int k; /* node to move down */ 455 { 456 int v = s->heap[k]; 457 int j = k << 1; /* left son of k */ 458 while (j <= s->heap_len) { 459 /* Set j to the smallest of the two sons: */ 460 if (j < s->heap_len && 461 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { 462 j++; 463 } 464 /* Exit if v is smaller than both sons */ 465 if (smaller(tree, v, s->heap[j], s->depth)) break; 466 467 /* Exchange v with the smallest son */ 468 s->heap[k] = s->heap[j]; k = j; 469 470 /* And continue down the tree, setting j to the left son of k */ 471 j <<= 1; 472 } 473 s->heap[k] = v; 474 } 475 476 /* =========================================================================== 477 * Compute the optimal bit lengths for a tree and update the total bit length 478 * for the current block. 479 * IN assertion: the fields freq and dad are set, heap[heap_max] and 480 * above are the tree nodes sorted by increasing frequency. 481 * OUT assertions: the field len is set to the optimal bit length, the 482 * array bl_count contains the frequencies for each bit length. 483 * The length opt_len is updated; static_len is also updated if stree is 484 * not null. 485 */ 486 local void gen_bitlen(s, desc) 487 deflate_state *s; 488 tree_desc *desc; /* the tree descriptor */ 489 { 490 ct_data *tree = desc->dyn_tree; 491 int max_code = desc->max_code; 492 const ct_data *stree = desc->stat_desc->static_tree; 493 const intf *extra = desc->stat_desc->extra_bits; 494 int base = desc->stat_desc->extra_base; 495 int max_length = desc->stat_desc->max_length; 496 int h; /* heap index */ 497 int n, m; /* iterate over the tree elements */ 498 int bits; /* bit length */ 499 int xbits; /* extra bits */ 500 ush f; /* frequency */ 501 int overflow = 0; /* number of elements with bit length too large */ 502 503 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0; 504 505 /* In a first pass, compute the optimal bit lengths (which may 506 * overflow in the case of the bit length tree). 507 */ 508 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ 509 510 for (h = s->heap_max+1; h < HEAP_SIZE; h++) { 511 n = s->heap[h]; 512 bits = tree[tree[n].Dad].Len + 1; 513 if (bits > max_length) bits = max_length, overflow++; 514 tree[n].Len = (ush)bits; 515 /* We overwrite tree[n].Dad which is no longer needed */ 516 517 if (n > max_code) continue; /* not a leaf node */ 518 519 s->bl_count[bits]++; 520 xbits = 0; 521 if (n >= base) xbits = extra[n-base]; 522 f = tree[n].Freq; 523 s->opt_len += (ulg)f * (unsigned)(bits + xbits); 524 if (stree) s->static_len += (ulg)f * (unsigned)(stree[n].Len + xbits); 525 } 526 if (overflow == 0) return; 527 528 Tracev((stderr,"\nbit length overflow\n")); 529 /* This happens for example on obj2 and pic of the Calgary corpus */ 530 531 /* Find the first bit length which could increase: */ 532 do { 533 bits = max_length-1; 534 while (s->bl_count[bits] == 0) bits--; 535 s->bl_count[bits]--; /* move one leaf down the tree */ 536 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */ 537 s->bl_count[max_length]--; 538 /* The brother of the overflow item also moves one step up, 539 * but this does not affect bl_count[max_length] 540 */ 541 overflow -= 2; 542 } while (overflow > 0); 543 544 /* Now recompute all bit lengths, scanning in increasing frequency. 545 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all 546 * lengths instead of fixing only the wrong ones. This idea is taken 547 * from 'ar' written by Haruhiko Okumura.) 548 */ 549 for (bits = max_length; bits != 0; bits--) { 550 n = s->bl_count[bits]; 551 while (n != 0) { 552 m = s->heap[--h]; 553 if (m > max_code) continue; 554 if ((unsigned) tree[m].Len != (unsigned) bits) { 555 Tracev((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); 556 s->opt_len += ((ulg)bits - tree[m].Len) * tree[m].Freq; 557 tree[m].Len = (ush)bits; 558 } 559 n--; 560 } 561 } 562 } 563 564 /* =========================================================================== 565 * Generate the codes for a given tree and bit counts (which need not be 566 * optimal). 567 * IN assertion: the array bl_count contains the bit length statistics for 568 * the given tree and the field len is set for all tree elements. 569 * OUT assertion: the field code is set for all tree elements of non 570 * zero code length. 571 */ 572 local void gen_codes (tree, max_code, bl_count) 573 ct_data *tree; /* the tree to decorate */ 574 int max_code; /* largest code with non zero frequency */ 575 ushf *bl_count; /* number of codes at each bit length */ 576 { 577 ush next_code[MAX_BITS+1]; /* next code value for each bit length */ 578 unsigned code = 0; /* running code value */ 579 int bits; /* bit index */ 580 int n; /* code index */ 581 582 /* The distribution counts are first used to generate the code values 583 * without bit reversal. 584 */ 585 for (bits = 1; bits <= MAX_BITS; bits++) { 586 code = (code + bl_count[bits-1]) << 1; 587 next_code[bits] = (ush)code; 588 } 589 /* Check that the bit counts in bl_count are consistent. The last code 590 * must be all ones. 591 */ 592 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, 593 "inconsistent bit counts"); 594 Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); 595 596 for (n = 0; n <= max_code; n++) { 597 int len = tree[n].Len; 598 if (len == 0) continue; 599 /* Now reverse the bits */ 600 tree[n].Code = (ush)bi_reverse(next_code[len]++, len); 601 602 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", 603 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); 604 } 605 } 606 607 /* =========================================================================== 608 * Construct one Huffman tree and assigns the code bit strings and lengths. 609 * Update the total bit length for the current block. 610 * IN assertion: the field freq is set for all tree elements. 611 * OUT assertions: the fields len and code are set to the optimal bit length 612 * and corresponding code. The length opt_len is updated; static_len is 613 * also updated if stree is not null. The field max_code is set. 614 */ 615 local void build_tree(s, desc) 616 deflate_state *s; 617 tree_desc *desc; /* the tree descriptor */ 618 { 619 ct_data *tree = desc->dyn_tree; 620 const ct_data *stree = desc->stat_desc->static_tree; 621 int elems = desc->stat_desc->elems; 622 int n, m; /* iterate over heap elements */ 623 int max_code = -1; /* largest code with non zero frequency */ 624 int node; /* new node being created */ 625 626 /* Construct the initial heap, with least frequent element in 627 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. 628 * heap[0] is not used. 629 */ 630 s->heap_len = 0, s->heap_max = HEAP_SIZE; 631 632 for (n = 0; n < elems; n++) { 633 if (tree[n].Freq != 0) { 634 s->heap[++(s->heap_len)] = max_code = n; 635 s->depth[n] = 0; 636 } else { 637 tree[n].Len = 0; 638 } 639 } 640 641 /* The pkzip format requires that at least one distance code exists, 642 * and that at least one bit should be sent even if there is only one 643 * possible code. So to avoid special checks later on we force at least 644 * two codes of non zero frequency. 645 */ 646 while (s->heap_len < 2) { 647 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0); 648 tree[node].Freq = 1; 649 s->depth[node] = 0; 650 s->opt_len--; if (stree) s->static_len -= stree[node].Len; 651 /* node is 0 or 1 so it does not have extra bits */ 652 } 653 desc->max_code = max_code; 654 655 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, 656 * establish sub-heaps of increasing lengths: 657 */ 658 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n); 659 660 /* Construct the Huffman tree by repeatedly combining the least two 661 * frequent nodes. 662 */ 663 node = elems; /* next internal node of the tree */ 664 do { 665 pqremove(s, tree, n); /* n = node of least frequency */ 666 m = s->heap[SMALLEST]; /* m = node of next least frequency */ 667 668 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */ 669 s->heap[--(s->heap_max)] = m; 670 671 /* Create a new node father of n and m */ 672 tree[node].Freq = tree[n].Freq + tree[m].Freq; 673 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ? 674 s->depth[n] : s->depth[m]) + 1); 675 tree[n].Dad = tree[m].Dad = (ush)node; 676 #ifdef DUMP_BL_TREE 677 if (tree == s->bl_tree) { 678 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", 679 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); 680 } 681 #endif 682 /* and insert the new node in the heap */ 683 s->heap[SMALLEST] = node++; 684 pqdownheap(s, tree, SMALLEST); 685 686 } while (s->heap_len >= 2); 687 688 s->heap[--(s->heap_max)] = s->heap[SMALLEST]; 689 690 /* At this point, the fields freq and dad are set. We can now 691 * generate the bit lengths. 692 */ 693 gen_bitlen(s, (tree_desc *)desc); 694 695 /* The field len is now set, we can generate the bit codes */ 696 gen_codes ((ct_data *)tree, max_code, s->bl_count); 697 } 698 699 /* =========================================================================== 700 * Scan a literal or distance tree to determine the frequencies of the codes 701 * in the bit length tree. 702 */ 703 local void scan_tree (s, tree, max_code) 704 deflate_state *s; 705 ct_data *tree; /* the tree to be scanned */ 706 int max_code; /* and its largest code of non zero frequency */ 707 { 708 int n; /* iterates over all tree elements */ 709 int prevlen = -1; /* last emitted length */ 710 int curlen; /* length of current code */ 711 int nextlen = tree[0].Len; /* length of next code */ 712 int count = 0; /* repeat count of the current code */ 713 int max_count = 7; /* max repeat count */ 714 int min_count = 4; /* min repeat count */ 715 716 if (nextlen == 0) max_count = 138, min_count = 3; 717 tree[max_code+1].Len = (ush)0xffff; /* guard */ 718 719 for (n = 0; n <= max_code; n++) { 720 curlen = nextlen; nextlen = tree[n+1].Len; 721 if (++count < max_count && curlen == nextlen) { 722 continue; 723 } else if (count < min_count) { 724 s->bl_tree[curlen].Freq += count; 725 } else if (curlen != 0) { 726 if (curlen != prevlen) s->bl_tree[curlen].Freq++; 727 s->bl_tree[REP_3_6].Freq++; 728 } else if (count <= 10) { 729 s->bl_tree[REPZ_3_10].Freq++; 730 } else { 731 s->bl_tree[REPZ_11_138].Freq++; 732 } 733 count = 0; prevlen = curlen; 734 if (nextlen == 0) { 735 max_count = 138, min_count = 3; 736 } else if (curlen == nextlen) { 737 max_count = 6, min_count = 3; 738 } else { 739 max_count = 7, min_count = 4; 740 } 741 } 742 } 743 744 /* =========================================================================== 745 * Send a literal or distance tree in compressed form, using the codes in 746 * bl_tree. 747 */ 748 local void send_tree (s, tree, max_code) 749 deflate_state *s; 750 ct_data *tree; /* the tree to be scanned */ 751 int max_code; /* and its largest code of non zero frequency */ 752 { 753 int n; /* iterates over all tree elements */ 754 int prevlen = -1; /* last emitted length */ 755 int curlen; /* length of current code */ 756 int nextlen = tree[0].Len; /* length of next code */ 757 int count = 0; /* repeat count of the current code */ 758 int max_count = 7; /* max repeat count */ 759 int min_count = 4; /* min repeat count */ 760 761 /* tree[max_code+1].Len = -1; */ /* guard already set */ 762 if (nextlen == 0) max_count = 138, min_count = 3; 763 764 for (n = 0; n <= max_code; n++) { 765 curlen = nextlen; nextlen = tree[n+1].Len; 766 if (++count < max_count && curlen == nextlen) { 767 continue; 768 } else if (count < min_count) { 769 do { send_code(s, curlen, s->bl_tree); } while (--count != 0); 770 771 } else if (curlen != 0) { 772 if (curlen != prevlen) { 773 send_code(s, curlen, s->bl_tree); count--; 774 } 775 Assert(count >= 3 && count <= 6, " 3_6?"); 776 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2); 777 778 } else if (count <= 10) { 779 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3); 780 781 } else { 782 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7); 783 } 784 count = 0; prevlen = curlen; 785 if (nextlen == 0) { 786 max_count = 138, min_count = 3; 787 } else if (curlen == nextlen) { 788 max_count = 6, min_count = 3; 789 } else { 790 max_count = 7, min_count = 4; 791 } 792 } 793 } 794 795 /* =========================================================================== 796 * Construct the Huffman tree for the bit lengths and return the index in 797 * bl_order of the last bit length code to send. 798 */ 799 local int build_bl_tree(s) 800 deflate_state *s; 801 { 802 int max_blindex; /* index of last bit length code of non zero freq */ 803 804 /* Determine the bit length frequencies for literal and distance trees */ 805 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code); 806 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code); 807 808 /* Build the bit length tree: */ 809 build_tree(s, (tree_desc *)(&(s->bl_desc))); 810 /* opt_len now includes the length of the tree representations, except 811 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. 812 */ 813 814 /* Determine the number of bit length codes to send. The pkzip format 815 * requires that at least 4 bit length codes be sent. (appnote.txt says 816 * 3 but the actual value used is 4.) 817 */ 818 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { 819 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break; 820 } 821 /* Update opt_len to include the bit length tree and counts */ 822 s->opt_len += 3*((ulg)max_blindex+1) + 5+5+4; 823 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", 824 s->opt_len, s->static_len)); 825 826 return max_blindex; 827 } 828 829 /* =========================================================================== 830 * Send the header for a block using dynamic Huffman trees: the counts, the 831 * lengths of the bit length codes, the literal tree and the distance tree. 832 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. 833 */ 834 local void send_all_trees(s, lcodes, dcodes, blcodes) 835 deflate_state *s; 836 int lcodes, dcodes, blcodes; /* number of codes for each tree */ 837 { 838 int rank; /* index in bl_order */ 839 840 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); 841 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, 842 "too many codes"); 843 Tracev((stderr, "\nbl counts: ")); 844 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */ 845 send_bits(s, dcodes-1, 5); 846 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */ 847 for (rank = 0; rank < blcodes; rank++) { 848 Tracev((stderr, "\nbl code %2d ", bl_order[rank])); 849 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3); 850 } 851 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent)); 852 853 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */ 854 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent)); 855 856 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */ 857 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent)); 858 } 859 860 /* =========================================================================== 861 * Send a stored block 862 */ 863 void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last) 864 deflate_state *s; 865 charf *buf; /* input block */ 866 ulg stored_len; /* length of input block */ 867 int last; /* one if this is the last block for a file */ 868 { 869 send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */ 870 bi_windup(s); /* align on byte boundary */ 871 put_short(s, (ush)stored_len); 872 put_short(s, (ush)~stored_len); 873 zmemcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len); 874 s->pending += stored_len; 875 #ifdef ZLIB_DEBUG 876 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L; 877 s->compressed_len += (stored_len + 4) << 3; 878 s->bits_sent += 2*16; 879 s->bits_sent += stored_len<<3; 880 #endif 881 } 882 883 /* =========================================================================== 884 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits) 885 */ 886 void ZLIB_INTERNAL _tr_flush_bits(s) 887 deflate_state *s; 888 { 889 bi_flush(s); 890 } 891 892 /* =========================================================================== 893 * Send one empty static block to give enough lookahead for inflate. 894 * This takes 10 bits, of which 7 may remain in the bit buffer. 895 */ 896 void ZLIB_INTERNAL _tr_align(s) 897 deflate_state *s; 898 { 899 send_bits(s, STATIC_TREES<<1, 3); 900 send_code(s, END_BLOCK, static_ltree); 901 #ifdef ZLIB_DEBUG 902 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ 903 #endif 904 bi_flush(s); 905 } 906 907 /* =========================================================================== 908 * Determine the best encoding for the current block: dynamic trees, static 909 * trees or store, and write out the encoded block. 910 */ 911 void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last) 912 deflate_state *s; 913 charf *buf; /* input block, or NULL if too old */ 914 ulg stored_len; /* length of input block */ 915 int last; /* one if this is the last block for a file */ 916 { 917 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ 918 int max_blindex = 0; /* index of last bit length code of non zero freq */ 919 920 /* Build the Huffman trees unless a stored block is forced */ 921 if (s->level > 0) { 922 923 /* Check if the file is binary or text */ 924 if (s->strm->data_type == Z_UNKNOWN) 925 s->strm->data_type = detect_data_type(s); 926 927 /* Construct the literal and distance trees */ 928 build_tree(s, (tree_desc *)(&(s->l_desc))); 929 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len, 930 s->static_len)); 931 932 build_tree(s, (tree_desc *)(&(s->d_desc))); 933 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len, 934 s->static_len)); 935 /* At this point, opt_len and static_len are the total bit lengths of 936 * the compressed block data, excluding the tree representations. 937 */ 938 939 /* Build the bit length tree for the above two trees, and get the index 940 * in bl_order of the last bit length code to send. 941 */ 942 max_blindex = build_bl_tree(s); 943 944 /* Determine the best encoding. Compute the block lengths in bytes. */ 945 opt_lenb = (s->opt_len+3+7)>>3; 946 static_lenb = (s->static_len+3+7)>>3; 947 948 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ", 949 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, 950 s->last_lit)); 951 952 if (static_lenb <= opt_lenb) opt_lenb = static_lenb; 953 954 } else { 955 Assert(buf != (char*)0, "lost buf"); 956 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */ 957 } 958 959 #ifdef FORCE_STORED 960 if (buf != (char*)0) { /* force stored block */ 961 #else 962 if (stored_len+4 <= opt_lenb && buf != (char*)0) { 963 /* 4: two words for the lengths */ 964 #endif 965 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. 966 * Otherwise we can't have processed more than WSIZE input bytes since 967 * the last block flush, because compression would have been 968 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to 969 * transform a block into a stored block. 970 */ 971 _tr_stored_block(s, buf, stored_len, last); 972 973 #ifdef FORCE_STATIC 974 } else if (static_lenb >= 0) { /* force static trees */ 975 #else 976 } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) { 977 #endif 978 send_bits(s, (STATIC_TREES<<1)+last, 3); 979 compress_block(s, (const ct_data *)static_ltree, 980 (const ct_data *)static_dtree); 981 #ifdef ZLIB_DEBUG 982 s->compressed_len += 3 + s->static_len; 983 #endif 984 } else { 985 send_bits(s, (DYN_TREES<<1)+last, 3); 986 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1, 987 max_blindex+1); 988 compress_block(s, (const ct_data *)s->dyn_ltree, 989 (const ct_data *)s->dyn_dtree); 990 #ifdef ZLIB_DEBUG 991 s->compressed_len += 3 + s->opt_len; 992 #endif 993 } 994 Assert (s->compressed_len == s->bits_sent, "bad compressed size"); 995 /* The above check is made mod 2^32, for files larger than 512 MB 996 * and uLong implemented on 32 bits. 997 */ 998 init_block(s); 999 1000 if (last) { 1001 bi_windup(s); 1002 #ifdef ZLIB_DEBUG 1003 s->compressed_len += 7; /* align on byte boundary */ 1004 #endif 1005 } 1006 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3, 1007 s->compressed_len-7*last)); 1008 } 1009 1010 /* =========================================================================== 1011 * Save the match info and tally the frequency counts. Return true if 1012 * the current block must be flushed. 1013 */ 1014 int ZLIB_INTERNAL _tr_tally (s, dist, lc) 1015 deflate_state *s; 1016 unsigned dist; /* distance of matched string */ 1017 unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ 1018 { 1019 s->d_buf[s->last_lit] = (ush)dist; 1020 s->l_buf[s->last_lit++] = (uch)lc; 1021 if (dist == 0) { 1022 /* lc is the unmatched char */ 1023 s->dyn_ltree[lc].Freq++; 1024 } else { 1025 s->matches++; 1026 /* Here, lc is the match length - MIN_MATCH */ 1027 dist--; /* dist = match distance - 1 */ 1028 Assert((ush)dist < (ush)MAX_DIST(s) && 1029 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && 1030 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match"); 1031 1032 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++; 1033 s->dyn_dtree[d_code(dist)].Freq++; 1034 } 1035 1036 #ifdef TRUNCATE_BLOCK 1037 /* Try to guess if it is profitable to stop the current block here */ 1038 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) { 1039 /* Compute an upper bound for the compressed length */ 1040 ulg out_length = (ulg)s->last_lit*8L; 1041 ulg in_length = (ulg)((long)s->strstart - s->block_start); 1042 int dcode; 1043 for (dcode = 0; dcode < D_CODES; dcode++) { 1044 out_length += (ulg)s->dyn_dtree[dcode].Freq * 1045 (5L+extra_dbits[dcode]); 1046 } 1047 out_length >>= 3; 1048 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ", 1049 s->last_lit, in_length, out_length, 1050 100L - out_length*100L/in_length)); 1051 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1; 1052 } 1053 #endif 1054 return (s->last_lit == s->lit_bufsize-1); 1055 /* We avoid equality with lit_bufsize because of wraparound at 64K 1056 * on 16 bit machines and because stored blocks are restricted to 1057 * 64K-1 bytes. 1058 */ 1059 } 1060 1061 /* =========================================================================== 1062 * Send the block data compressed using the given Huffman trees 1063 */ 1064 local void compress_block(s, ltree, dtree) 1065 deflate_state *s; 1066 const ct_data *ltree; /* literal tree */ 1067 const ct_data *dtree; /* distance tree */ 1068 { 1069 unsigned dist; /* distance of matched string */ 1070 int lc; /* match length or unmatched char (if dist == 0) */ 1071 unsigned lx = 0; /* running index in l_buf */ 1072 unsigned code; /* the code to send */ 1073 int extra; /* number of extra bits to send */ 1074 1075 if (s->last_lit != 0) do { 1076 dist = s->d_buf[lx]; 1077 lc = s->l_buf[lx++]; 1078 if (dist == 0) { 1079 send_code(s, lc, ltree); /* send a literal byte */ 1080 Tracecv(isgraph(lc), (stderr," '%c' ", lc)); 1081 } else { 1082 /* Here, lc is the match length - MIN_MATCH */ 1083 code = _length_code[lc]; 1084 send_code(s, code+LITERALS+1, ltree); /* send the length code */ 1085 extra = extra_lbits[code]; 1086 if (extra != 0) { 1087 lc -= base_length[code]; 1088 send_bits(s, lc, extra); /* send the extra length bits */ 1089 } 1090 dist--; /* dist is now the match distance - 1 */ 1091 code = d_code(dist); 1092 Assert (code < D_CODES, "bad d_code"); 1093 1094 send_code(s, code, dtree); /* send the distance code */ 1095 extra = extra_dbits[code]; 1096 if (extra != 0) { 1097 dist -= (unsigned)base_dist[code]; 1098 send_bits(s, dist, extra); /* send the extra distance bits */ 1099 } 1100 } /* literal or match pair ? */ 1101 1102 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */ 1103 Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx, 1104 "pendingBuf overflow"); 1105 1106 } while (lx < s->last_lit); 1107 1108 send_code(s, END_BLOCK, ltree); 1109 } 1110 1111 /* =========================================================================== 1112 * Check if the data type is TEXT or BINARY, using the following algorithm: 1113 * - TEXT if the two conditions below are satisfied: 1114 * a) There are no non-portable control characters belonging to the 1115 * "black list" (0..6, 14..25, 28..31). 1116 * b) There is at least one printable character belonging to the 1117 * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255). 1118 * - BINARY otherwise. 1119 * - The following partially-portable control characters form a 1120 * "gray list" that is ignored in this detection algorithm: 1121 * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}). 1122 * IN assertion: the fields Freq of dyn_ltree are set. 1123 */ 1124 local int detect_data_type(s) 1125 deflate_state *s; 1126 { 1127 /* black_mask is the bit mask of black-listed bytes 1128 * set bits 0..6, 14..25, and 28..31 1129 * 0xf3ffc07f = binary 11110011111111111100000001111111 1130 */ 1131 unsigned long black_mask = 0xf3ffc07fUL; 1132 int n; 1133 1134 /* Check for non-textual ("black-listed") bytes. */ 1135 for (n = 0; n <= 31; n++, black_mask >>= 1) 1136 if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0)) 1137 return Z_BINARY; 1138 1139 /* Check for textual ("white-listed") bytes. */ 1140 if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0 1141 || s->dyn_ltree[13].Freq != 0) 1142 return Z_TEXT; 1143 for (n = 32; n < LITERALS; n++) 1144 if (s->dyn_ltree[n].Freq != 0) 1145 return Z_TEXT; 1146 1147 /* There are no "black-listed" or "white-listed" bytes: 1148 * this stream either is empty or has tolerated ("gray-listed") bytes only. 1149 */ 1150 return Z_BINARY; 1151 } 1152 1153 /* =========================================================================== 1154 * Reverse the first len bits of a code, using straightforward code (a faster 1155 * method would use a table) 1156 * IN assertion: 1 <= len <= 15 1157 */ 1158 local unsigned bi_reverse(code, len) 1159 unsigned code; /* the value to invert */ 1160 int len; /* its bit length */ 1161 { 1162 register unsigned res = 0; 1163 do { 1164 res |= code & 1; 1165 code >>= 1, res <<= 1; 1166 } while (--len > 0); 1167 return res >> 1; 1168 } 1169 1170 /* =========================================================================== 1171 * Flush the bit buffer, keeping at most 7 bits in it. 1172 */ 1173 local void bi_flush(s) 1174 deflate_state *s; 1175 { 1176 if (s->bi_valid == 16) { 1177 put_short(s, s->bi_buf); 1178 s->bi_buf = 0; 1179 s->bi_valid = 0; 1180 } else if (s->bi_valid >= 8) { 1181 put_byte(s, (Byte)s->bi_buf); 1182 s->bi_buf >>= 8; 1183 s->bi_valid -= 8; 1184 } 1185 } 1186 1187 /* =========================================================================== 1188 * Flush the bit buffer and align the output on a byte boundary 1189 */ 1190 local void bi_windup(s) 1191 deflate_state *s; 1192 { 1193 if (s->bi_valid > 8) { 1194 put_short(s, s->bi_buf); 1195 } else if (s->bi_valid > 0) { 1196 put_byte(s, (Byte)s->bi_buf); 1197 } 1198 s->bi_buf = 0; 1199 s->bi_valid = 0; 1200 #ifdef ZLIB_DEBUG 1201 s->bits_sent = (s->bits_sent+7) & ~7; 1202 #endif 1203 }