File indexing completed on 2024-04-14 03:46:49
0001 /* trees.c -- output deflated data using Huffman coding 0002 * Copyright (C) 1995-2012 Jean-loup Gailly 0003 * detect_data_type() function provided freely by Cosmin Truta, 2006 0004 * For conditions of distribution and use, see copyright notice in zlib.h 0005 */ 0006 0007 /* 0008 * ALGORITHM 0009 * 0010 * The "deflation" process uses several Huffman trees. The more 0011 * common source values are represented by shorter bit sequences. 0012 * 0013 * Each code tree is stored in a compressed form which is itself 0014 * a Huffman encoding of the lengths of all the code strings (in 0015 * ascending order by source values). The actual code strings are 0016 * reconstructed from the lengths in the inflate process, as described 0017 * in the deflate specification. 0018 * 0019 * REFERENCES 0020 * 0021 * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification". 0022 * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc 0023 * 0024 * Storer, James A. 0025 * Data Compression: Methods and Theory, pp. 49-50. 0026 * Computer Science Press, 1988. ISBN 0-7167-8156-5. 0027 * 0028 * Sedgewick, R. 0029 * Algorithms, p290. 0030 * Addison-Wesley, 1983. ISBN 0-201-06672-6. 0031 */ 0032 0033 /* @(#) $Id$ */ 0034 0035 /* #define GEN_TREES_H */ 0036 0037 #include "deflate.h" 0038 0039 #ifdef DEBUG 0040 # include <ctype.h> 0041 #endif 0042 0043 /* =========================================================================== 0044 * Constants 0045 */ 0046 0047 #define MAX_BL_BITS 7 0048 /* Bit length codes must not exceed MAX_BL_BITS bits */ 0049 0050 #define END_BLOCK 256 0051 /* end of block literal code */ 0052 0053 #define REP_3_6 16 0054 /* repeat previous bit length 3-6 times (2 bits of repeat count) */ 0055 0056 #define REPZ_3_10 17 0057 /* repeat a zero length 3-10 times (3 bits of repeat count) */ 0058 0059 #define REPZ_11_138 18 0060 /* repeat a zero length 11-138 times (7 bits of repeat count) */ 0061 0062 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ 0063 = {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}; 0064 0065 local const int extra_dbits[D_CODES] /* extra bits for each distance code */ 0066 = {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}; 0067 0068 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */ 0069 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; 0070 0071 local const uch bl_order[BL_CODES] 0072 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; 0073 /* The lengths of the bit length codes are sent in order of decreasing 0074 * probability, to avoid transmitting the lengths for unused bit length codes. 0075 */ 0076 0077 /* =========================================================================== 0078 * Local data. These are initialized only once. 0079 */ 0080 0081 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */ 0082 0083 #if defined(GEN_TREES_H) || !defined(STDC) 0084 /* non ANSI compilers may not accept trees.h */ 0085 0086 local ct_data static_ltree[L_CODES+2]; 0087 /* The static literal tree. Since the bit lengths are imposed, there is no 0088 * need for the L_CODES extra codes used during heap construction. However 0089 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init 0090 * below). 0091 */ 0092 0093 local ct_data static_dtree[D_CODES]; 0094 /* The static distance tree. (Actually a trivial tree since all codes use 0095 * 5 bits.) 0096 */ 0097 0098 uch _dist_code[DIST_CODE_LEN]; 0099 /* Distance codes. The first 256 values correspond to the distances 0100 * 3 .. 258, the last 256 values correspond to the top 8 bits of 0101 * the 15 bit distances. 0102 */ 0103 0104 uch _length_code[MAX_MATCH-MIN_MATCH+1]; 0105 /* length code for each normalized match length (0 == MIN_MATCH) */ 0106 0107 local int base_length[LENGTH_CODES]; 0108 /* First normalized length for each code (0 = MIN_MATCH) */ 0109 0110 local int base_dist[D_CODES]; 0111 /* First normalized distance for each code (0 = distance of 1) */ 0112 0113 #else 0114 # include "trees.h" 0115 #endif /* GEN_TREES_H */ 0116 0117 struct static_tree_desc_s { 0118 const ct_data *static_tree; /* static tree or NULL */ 0119 const intf *extra_bits; /* extra bits for each code or NULL */ 0120 int extra_base; /* base index for extra_bits */ 0121 int elems; /* max number of elements in the tree */ 0122 int max_length; /* max bit length for the codes */ 0123 }; 0124 0125 local static_tree_desc static_l_desc = 0126 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; 0127 0128 local static_tree_desc static_d_desc = 0129 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; 0130 0131 local static_tree_desc static_bl_desc = 0132 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; 0133 0134 /* =========================================================================== 0135 * Local (static) routines in this file. 0136 */ 0137 0138 local void tr_static_init OF((void)); 0139 local void init_block OF((deflate_state *s)); 0140 local void pqdownheap OF((deflate_state *s, ct_data *tree, int k)); 0141 local void gen_bitlen OF((deflate_state *s, tree_desc *desc)); 0142 local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count)); 0143 local void build_tree OF((deflate_state *s, tree_desc *desc)); 0144 local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code)); 0145 local void send_tree OF((deflate_state *s, ct_data *tree, int max_code)); 0146 local int build_bl_tree OF((deflate_state *s)); 0147 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes, 0148 int blcodes)); 0149 local void compress_block OF((deflate_state *s, const ct_data *ltree, 0150 const ct_data *dtree)); 0151 local int detect_data_type OF((deflate_state *s)); 0152 local unsigned bi_reverse OF((unsigned value, int length)); 0153 local void bi_windup OF((deflate_state *s)); 0154 local void bi_flush OF((deflate_state *s)); 0155 local void copy_block OF((deflate_state *s, charf *buf, unsigned len, 0156 int header)); 0157 0158 #ifdef GEN_TREES_H 0159 local void gen_trees_header OF((void)); 0160 #endif 0161 0162 #ifndef DEBUG 0163 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len) 0164 /* Send a code of the given tree. c and tree must not have side effects */ 0165 0166 #else /* DEBUG */ 0167 # define send_code(s, c, tree) \ 0168 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \ 0169 send_bits(s, tree[c].Code, tree[c].Len); } 0170 #endif 0171 0172 /* =========================================================================== 0173 * Output a short LSB first on the stream. 0174 * IN assertion: there is enough room in pendingBuf. 0175 */ 0176 #define put_short(s, w) { \ 0177 put_byte(s, (uch)((w) & 0xff)); \ 0178 put_byte(s, (uch)((ush)(w) >> 8)); \ 0179 } 0180 0181 /* =========================================================================== 0182 * Send a value on a given number of bits. 0183 * IN assertion: length <= 16 and value fits in length bits. 0184 */ 0185 #ifdef DEBUG 0186 local void send_bits OF((deflate_state *s, int value, int length)); 0187 0188 local void send_bits(s, value, length) 0189 deflate_state *s; 0190 int value; /* value to send */ 0191 int length; /* number of bits */ 0192 { 0193 Tracevv((stderr," l %2d v %4x ", length, value)); 0194 Assert(length > 0 && length <= 15, "invalid length"); 0195 s->bits_sent += (ulg)length; 0196 0197 /* If not enough room in bi_buf, use (valid) bits from bi_buf and 0198 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid)) 0199 * unused bits in value. 0200 */ 0201 if (s->bi_valid > (int)Buf_size - length) { 0202 s->bi_buf |= (ush)value << s->bi_valid; 0203 put_short(s, s->bi_buf); 0204 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid); 0205 s->bi_valid += length - Buf_size; 0206 } else { 0207 s->bi_buf |= (ush)value << s->bi_valid; 0208 s->bi_valid += length; 0209 } 0210 } 0211 #else /* !DEBUG */ 0212 0213 #define send_bits(s, value, length) \ 0214 { int len = length;\ 0215 if (s->bi_valid > (int)Buf_size - len) {\ 0216 int val = value;\ 0217 s->bi_buf |= (ush)val << s->bi_valid;\ 0218 put_short(s, s->bi_buf);\ 0219 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\ 0220 s->bi_valid += len - Buf_size;\ 0221 } else {\ 0222 s->bi_buf |= (ush)(value) << s->bi_valid;\ 0223 s->bi_valid += len;\ 0224 }\ 0225 } 0226 #endif /* DEBUG */ 0227 0228 0229 /* the arguments must not have side effects */ 0230 0231 /* =========================================================================== 0232 * Initialize the various 'constant' tables. 0233 */ 0234 local void tr_static_init() 0235 { 0236 #if defined(GEN_TREES_H) || !defined(STDC) 0237 static int static_init_done = 0; 0238 int n; /* iterates over tree elements */ 0239 int bits; /* bit counter */ 0240 int length; /* length value */ 0241 int code; /* code value */ 0242 int dist; /* distance index */ 0243 ush bl_count[MAX_BITS+1]; 0244 /* number of codes at each bit length for an optimal tree */ 0245 0246 if (static_init_done) return; 0247 0248 /* For some embedded targets, global variables are not initialized: */ 0249 #ifdef NO_INIT_GLOBAL_POINTERS 0250 static_l_desc.static_tree = static_ltree; 0251 static_l_desc.extra_bits = extra_lbits; 0252 static_d_desc.static_tree = static_dtree; 0253 static_d_desc.extra_bits = extra_dbits; 0254 static_bl_desc.extra_bits = extra_blbits; 0255 #endif 0256 0257 /* Initialize the mapping length (0..255) -> length code (0..28) */ 0258 length = 0; 0259 for (code = 0; code < LENGTH_CODES-1; code++) { 0260 base_length[code] = length; 0261 for (n = 0; n < (1<<extra_lbits[code]); n++) { 0262 _length_code[length++] = (uch)code; 0263 } 0264 } 0265 Assert (length == 256, "tr_static_init: length != 256"); 0266 /* Note that the length 255 (match length 258) can be represented 0267 * in two different ways: code 284 + 5 bits or code 285, so we 0268 * overwrite length_code[255] to use the best encoding: 0269 */ 0270 _length_code[length-1] = (uch)code; 0271 0272 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ 0273 dist = 0; 0274 for (code = 0 ; code < 16; code++) { 0275 base_dist[code] = dist; 0276 for (n = 0; n < (1<<extra_dbits[code]); n++) { 0277 _dist_code[dist++] = (uch)code; 0278 } 0279 } 0280 Assert (dist == 256, "tr_static_init: dist != 256"); 0281 dist >>= 7; /* from now on, all distances are divided by 128 */ 0282 for ( ; code < D_CODES; code++) { 0283 base_dist[code] = dist << 7; 0284 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { 0285 _dist_code[256 + dist++] = (uch)code; 0286 } 0287 } 0288 Assert (dist == 256, "tr_static_init: 256+dist != 512"); 0289 0290 /* Construct the codes of the static literal tree */ 0291 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; 0292 n = 0; 0293 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; 0294 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; 0295 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; 0296 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; 0297 /* Codes 286 and 287 do not exist, but we must include them in the 0298 * tree construction to get a canonical Huffman tree (longest code 0299 * all ones) 0300 */ 0301 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count); 0302 0303 /* The static distance tree is trivial: */ 0304 for (n = 0; n < D_CODES; n++) { 0305 static_dtree[n].Len = 5; 0306 static_dtree[n].Code = bi_reverse((unsigned)n, 5); 0307 } 0308 static_init_done = 1; 0309 0310 # ifdef GEN_TREES_H 0311 gen_trees_header(); 0312 # endif 0313 #endif /* defined(GEN_TREES_H) || !defined(STDC) */ 0314 } 0315 0316 /* =========================================================================== 0317 * Genererate the file trees.h describing the static trees. 0318 */ 0319 #ifdef GEN_TREES_H 0320 # ifndef DEBUG 0321 # include <stdio.h> 0322 # endif 0323 0324 # define SEPARATOR(i, last, width) \ 0325 ((i) == (last)? "\n};\n\n" : \ 0326 ((i) % (width) == (width)-1 ? ",\n" : ", ")) 0327 0328 void gen_trees_header() 0329 { 0330 FILE *header = fopen("trees.h", "w"); 0331 int i; 0332 0333 Assert (header != NULL, "Can't open trees.h"); 0334 fprintf(header, 0335 "/* header created automatically with -DGEN_TREES_H */\n\n"); 0336 0337 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n"); 0338 for (i = 0; i < L_CODES+2; i++) { 0339 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code, 0340 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5)); 0341 } 0342 0343 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n"); 0344 for (i = 0; i < D_CODES; i++) { 0345 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code, 0346 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5)); 0347 } 0348 0349 fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n"); 0350 for (i = 0; i < DIST_CODE_LEN; i++) { 0351 fprintf(header, "%2u%s", _dist_code[i], 0352 SEPARATOR(i, DIST_CODE_LEN-1, 20)); 0353 } 0354 0355 fprintf(header, 0356 "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n"); 0357 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) { 0358 fprintf(header, "%2u%s", _length_code[i], 0359 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20)); 0360 } 0361 0362 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n"); 0363 for (i = 0; i < LENGTH_CODES; i++) { 0364 fprintf(header, "%1u%s", base_length[i], 0365 SEPARATOR(i, LENGTH_CODES-1, 20)); 0366 } 0367 0368 fprintf(header, "local const int base_dist[D_CODES] = {\n"); 0369 for (i = 0; i < D_CODES; i++) { 0370 fprintf(header, "%5u%s", base_dist[i], 0371 SEPARATOR(i, D_CODES-1, 10)); 0372 } 0373 0374 fclose(header); 0375 } 0376 #endif /* GEN_TREES_H */ 0377 0378 /* =========================================================================== 0379 * Initialize the tree data structures for a new zlib stream. 0380 */ 0381 void ZLIB_INTERNAL _tr_init(s) 0382 deflate_state *s; 0383 { 0384 tr_static_init(); 0385 0386 s->l_desc.dyn_tree = s->dyn_ltree; 0387 s->l_desc.stat_desc = &static_l_desc; 0388 0389 s->d_desc.dyn_tree = s->dyn_dtree; 0390 s->d_desc.stat_desc = &static_d_desc; 0391 0392 s->bl_desc.dyn_tree = s->bl_tree; 0393 s->bl_desc.stat_desc = &static_bl_desc; 0394 0395 s->bi_buf = 0; 0396 s->bi_valid = 0; 0397 #ifdef DEBUG 0398 s->compressed_len = 0L; 0399 s->bits_sent = 0L; 0400 #endif 0401 0402 /* Initialize the first block of the first file: */ 0403 init_block(s); 0404 } 0405 0406 /* =========================================================================== 0407 * Initialize a new block. 0408 */ 0409 local void init_block(s) 0410 deflate_state *s; 0411 { 0412 int n; /* iterates over tree elements */ 0413 0414 /* Initialize the trees. */ 0415 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0; 0416 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0; 0417 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0; 0418 0419 s->dyn_ltree[END_BLOCK].Freq = 1; 0420 s->opt_len = s->static_len = 0L; 0421 s->last_lit = s->matches = 0; 0422 } 0423 0424 #define SMALLEST 1 0425 /* Index within the heap array of least frequent node in the Huffman tree */ 0426 0427 0428 /* =========================================================================== 0429 * Remove the smallest element from the heap and recreate the heap with 0430 * one less element. Updates heap and heap_len. 0431 */ 0432 #define pqremove(s, tree, top) \ 0433 {\ 0434 top = s->heap[SMALLEST]; \ 0435 s->heap[SMALLEST] = s->heap[s->heap_len--]; \ 0436 pqdownheap(s, tree, SMALLEST); \ 0437 } 0438 0439 /* =========================================================================== 0440 * Compares to subtrees, using the tree depth as tie breaker when 0441 * the subtrees have equal frequency. This minimizes the worst case length. 0442 */ 0443 #define smaller(tree, n, m, depth) \ 0444 (tree[n].Freq < tree[m].Freq || \ 0445 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) 0446 0447 /* =========================================================================== 0448 * Restore the heap property by moving down the tree starting at node k, 0449 * exchanging a node with the smallest of its two sons if necessary, stopping 0450 * when the heap property is re-established (each father smaller than its 0451 * two sons). 0452 */ 0453 local void pqdownheap(s, tree, k) 0454 deflate_state *s; 0455 ct_data *tree; /* the tree to restore */ 0456 int k; /* node to move down */ 0457 { 0458 int v = s->heap[k]; 0459 int j = k << 1; /* left son of k */ 0460 while (j <= s->heap_len) { 0461 /* Set j to the smallest of the two sons: */ 0462 if (j < s->heap_len && 0463 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { 0464 j++; 0465 } 0466 /* Exit if v is smaller than both sons */ 0467 if (smaller(tree, v, s->heap[j], s->depth)) break; 0468 0469 /* Exchange v with the smallest son */ 0470 s->heap[k] = s->heap[j]; k = j; 0471 0472 /* And continue down the tree, setting j to the left son of k */ 0473 j <<= 1; 0474 } 0475 s->heap[k] = v; 0476 } 0477 0478 /* =========================================================================== 0479 * Compute the optimal bit lengths for a tree and update the total bit length 0480 * for the current block. 0481 * IN assertion: the fields freq and dad are set, heap[heap_max] and 0482 * above are the tree nodes sorted by increasing frequency. 0483 * OUT assertions: the field len is set to the optimal bit length, the 0484 * array bl_count contains the frequencies for each bit length. 0485 * The length opt_len is updated; static_len is also updated if stree is 0486 * not null. 0487 */ 0488 local void gen_bitlen(s, desc) 0489 deflate_state *s; 0490 tree_desc *desc; /* the tree descriptor */ 0491 { 0492 ct_data *tree = desc->dyn_tree; 0493 int max_code = desc->max_code; 0494 const ct_data *stree = desc->stat_desc->static_tree; 0495 const intf *extra = desc->stat_desc->extra_bits; 0496 int base = desc->stat_desc->extra_base; 0497 int max_length = desc->stat_desc->max_length; 0498 int h; /* heap index */ 0499 int n, m; /* iterate over the tree elements */ 0500 int bits; /* bit length */ 0501 int xbits; /* extra bits */ 0502 ush f; /* frequency */ 0503 int overflow = 0; /* number of elements with bit length too large */ 0504 0505 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0; 0506 0507 /* In a first pass, compute the optimal bit lengths (which may 0508 * overflow in the case of the bit length tree). 0509 */ 0510 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ 0511 0512 for (h = s->heap_max+1; h < HEAP_SIZE; h++) { 0513 n = s->heap[h]; 0514 bits = tree[tree[n].Dad].Len + 1; 0515 if (bits > max_length) bits = max_length, overflow++; 0516 tree[n].Len = (ush)bits; 0517 /* We overwrite tree[n].Dad which is no longer needed */ 0518 0519 if (n > max_code) continue; /* not a leaf node */ 0520 0521 s->bl_count[bits]++; 0522 xbits = 0; 0523 if (n >= base) xbits = extra[n-base]; 0524 f = tree[n].Freq; 0525 s->opt_len += (ulg)f * (bits + xbits); 0526 if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits); 0527 } 0528 if (overflow == 0) return; 0529 0530 Trace((stderr,"\nbit length overflow\n")); 0531 /* This happens for example on obj2 and pic of the Calgary corpus */ 0532 0533 /* Find the first bit length which could increase: */ 0534 do { 0535 bits = max_length-1; 0536 while (s->bl_count[bits] == 0) bits--; 0537 s->bl_count[bits]--; /* move one leaf down the tree */ 0538 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */ 0539 s->bl_count[max_length]--; 0540 /* The brother of the overflow item also moves one step up, 0541 * but this does not affect bl_count[max_length] 0542 */ 0543 overflow -= 2; 0544 } while (overflow > 0); 0545 0546 /* Now recompute all bit lengths, scanning in increasing frequency. 0547 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all 0548 * lengths instead of fixing only the wrong ones. This idea is taken 0549 * from 'ar' written by Haruhiko Okumura.) 0550 */ 0551 for (bits = max_length; bits != 0; bits--) { 0552 n = s->bl_count[bits]; 0553 while (n != 0) { 0554 m = s->heap[--h]; 0555 if (m > max_code) continue; 0556 if ((unsigned) tree[m].Len != (unsigned) bits) { 0557 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); 0558 s->opt_len += ((long)bits - (long)tree[m].Len) 0559 *(long)tree[m].Freq; 0560 tree[m].Len = (ush)bits; 0561 } 0562 n--; 0563 } 0564 } 0565 } 0566 0567 /* =========================================================================== 0568 * Generate the codes for a given tree and bit counts (which need not be 0569 * optimal). 0570 * IN assertion: the array bl_count contains the bit length statistics for 0571 * the given tree and the field len is set for all tree elements. 0572 * OUT assertion: the field code is set for all tree elements of non 0573 * zero code length. 0574 */ 0575 local void gen_codes (tree, max_code, bl_count) 0576 ct_data *tree; /* the tree to decorate */ 0577 int max_code; /* largest code with non zero frequency */ 0578 ushf *bl_count; /* number of codes at each bit length */ 0579 { 0580 ush next_code[MAX_BITS+1]; /* next code value for each bit length */ 0581 ush code = 0; /* running code value */ 0582 int bits; /* bit index */ 0583 int n; /* code index */ 0584 0585 /* The distribution counts are first used to generate the code values 0586 * without bit reversal. 0587 */ 0588 for (bits = 1; bits <= MAX_BITS; bits++) { 0589 next_code[bits] = code = (code + bl_count[bits-1]) << 1; 0590 } 0591 /* Check that the bit counts in bl_count are consistent. The last code 0592 * must be all ones. 0593 */ 0594 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, 0595 "inconsistent bit counts"); 0596 Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); 0597 0598 for (n = 0; n <= max_code; n++) { 0599 int len = tree[n].Len; 0600 if (len == 0) continue; 0601 /* Now reverse the bits */ 0602 tree[n].Code = bi_reverse(next_code[len]++, len); 0603 0604 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", 0605 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); 0606 } 0607 } 0608 0609 /* =========================================================================== 0610 * Construct one Huffman tree and assigns the code bit strings and lengths. 0611 * Update the total bit length for the current block. 0612 * IN assertion: the field freq is set for all tree elements. 0613 * OUT assertions: the fields len and code are set to the optimal bit length 0614 * and corresponding code. The length opt_len is updated; static_len is 0615 * also updated if stree is not null. The field max_code is set. 0616 */ 0617 local void build_tree(s, desc) 0618 deflate_state *s; 0619 tree_desc *desc; /* the tree descriptor */ 0620 { 0621 ct_data *tree = desc->dyn_tree; 0622 const ct_data *stree = desc->stat_desc->static_tree; 0623 int elems = desc->stat_desc->elems; 0624 int n, m; /* iterate over heap elements */ 0625 int max_code = -1; /* largest code with non zero frequency */ 0626 int node; /* new node being created */ 0627 0628 /* Construct the initial heap, with least frequent element in 0629 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. 0630 * heap[0] is not used. 0631 */ 0632 s->heap_len = 0, s->heap_max = HEAP_SIZE; 0633 0634 for (n = 0; n < elems; n++) { 0635 if (tree[n].Freq != 0) { 0636 s->heap[++(s->heap_len)] = max_code = n; 0637 s->depth[n] = 0; 0638 } else { 0639 tree[n].Len = 0; 0640 } 0641 } 0642 0643 /* The pkzip format requires that at least one distance code exists, 0644 * and that at least one bit should be sent even if there is only one 0645 * possible code. So to avoid special checks later on we force at least 0646 * two codes of non zero frequency. 0647 */ 0648 while (s->heap_len < 2) { 0649 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0); 0650 tree[node].Freq = 1; 0651 s->depth[node] = 0; 0652 s->opt_len--; if (stree) s->static_len -= stree[node].Len; 0653 /* node is 0 or 1 so it does not have extra bits */ 0654 } 0655 desc->max_code = max_code; 0656 0657 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, 0658 * establish sub-heaps of increasing lengths: 0659 */ 0660 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n); 0661 0662 /* Construct the Huffman tree by repeatedly combining the least two 0663 * frequent nodes. 0664 */ 0665 node = elems; /* next internal node of the tree */ 0666 do { 0667 pqremove(s, tree, n); /* n = node of least frequency */ 0668 m = s->heap[SMALLEST]; /* m = node of next least frequency */ 0669 0670 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */ 0671 s->heap[--(s->heap_max)] = m; 0672 0673 /* Create a new node father of n and m */ 0674 tree[node].Freq = tree[n].Freq + tree[m].Freq; 0675 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ? 0676 s->depth[n] : s->depth[m]) + 1); 0677 tree[n].Dad = tree[m].Dad = (ush)node; 0678 #ifdef DUMP_BL_TREE 0679 if (tree == s->bl_tree) { 0680 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", 0681 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); 0682 } 0683 #endif 0684 /* and insert the new node in the heap */ 0685 s->heap[SMALLEST] = node++; 0686 pqdownheap(s, tree, SMALLEST); 0687 0688 } while (s->heap_len >= 2); 0689 0690 s->heap[--(s->heap_max)] = s->heap[SMALLEST]; 0691 0692 /* At this point, the fields freq and dad are set. We can now 0693 * generate the bit lengths. 0694 */ 0695 gen_bitlen(s, (tree_desc *)desc); 0696 0697 /* The field len is now set, we can generate the bit codes */ 0698 gen_codes ((ct_data *)tree, max_code, s->bl_count); 0699 } 0700 0701 /* =========================================================================== 0702 * Scan a literal or distance tree to determine the frequencies of the codes 0703 * in the bit length tree. 0704 */ 0705 local void scan_tree (s, tree, max_code) 0706 deflate_state *s; 0707 ct_data *tree; /* the tree to be scanned */ 0708 int max_code; /* and its largest code of non zero frequency */ 0709 { 0710 int n; /* iterates over all tree elements */ 0711 int prevlen = -1; /* last emitted length */ 0712 int curlen; /* length of current code */ 0713 int nextlen = tree[0].Len; /* length of next code */ 0714 int count = 0; /* repeat count of the current code */ 0715 int max_count = 7; /* max repeat count */ 0716 int min_count = 4; /* min repeat count */ 0717 0718 if (nextlen == 0) max_count = 138, min_count = 3; 0719 tree[max_code+1].Len = (ush)0xffff; /* guard */ 0720 0721 for (n = 0; n <= max_code; n++) { 0722 curlen = nextlen; nextlen = tree[n+1].Len; 0723 if (++count < max_count && curlen == nextlen) { 0724 continue; 0725 } else if (count < min_count) { 0726 s->bl_tree[curlen].Freq += count; 0727 } else if (curlen != 0) { 0728 if (curlen != prevlen) s->bl_tree[curlen].Freq++; 0729 s->bl_tree[REP_3_6].Freq++; 0730 } else if (count <= 10) { 0731 s->bl_tree[REPZ_3_10].Freq++; 0732 } else { 0733 s->bl_tree[REPZ_11_138].Freq++; 0734 } 0735 count = 0; prevlen = curlen; 0736 if (nextlen == 0) { 0737 max_count = 138, min_count = 3; 0738 } else if (curlen == nextlen) { 0739 max_count = 6, min_count = 3; 0740 } else { 0741 max_count = 7, min_count = 4; 0742 } 0743 } 0744 } 0745 0746 /* =========================================================================== 0747 * Send a literal or distance tree in compressed form, using the codes in 0748 * bl_tree. 0749 */ 0750 local void send_tree (s, tree, max_code) 0751 deflate_state *s; 0752 ct_data *tree; /* the tree to be scanned */ 0753 int max_code; /* and its largest code of non zero frequency */ 0754 { 0755 int n; /* iterates over all tree elements */ 0756 int prevlen = -1; /* last emitted length */ 0757 int curlen; /* length of current code */ 0758 int nextlen = tree[0].Len; /* length of next code */ 0759 int count = 0; /* repeat count of the current code */ 0760 int max_count = 7; /* max repeat count */ 0761 int min_count = 4; /* min repeat count */ 0762 0763 /* tree[max_code+1].Len = -1; */ /* guard already set */ 0764 if (nextlen == 0) max_count = 138, min_count = 3; 0765 0766 for (n = 0; n <= max_code; n++) { 0767 curlen = nextlen; nextlen = tree[n+1].Len; 0768 if (++count < max_count && curlen == nextlen) { 0769 continue; 0770 } else if (count < min_count) { 0771 do { send_code(s, curlen, s->bl_tree); } while (--count != 0); 0772 0773 } else if (curlen != 0) { 0774 if (curlen != prevlen) { 0775 send_code(s, curlen, s->bl_tree); count--; 0776 } 0777 Assert(count >= 3 && count <= 6, " 3_6?"); 0778 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2); 0779 0780 } else if (count <= 10) { 0781 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3); 0782 0783 } else { 0784 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7); 0785 } 0786 count = 0; prevlen = curlen; 0787 if (nextlen == 0) { 0788 max_count = 138, min_count = 3; 0789 } else if (curlen == nextlen) { 0790 max_count = 6, min_count = 3; 0791 } else { 0792 max_count = 7, min_count = 4; 0793 } 0794 } 0795 } 0796 0797 /* =========================================================================== 0798 * Construct the Huffman tree for the bit lengths and return the index in 0799 * bl_order of the last bit length code to send. 0800 */ 0801 local int build_bl_tree(s) 0802 deflate_state *s; 0803 { 0804 int max_blindex; /* index of last bit length code of non zero freq */ 0805 0806 /* Determine the bit length frequencies for literal and distance trees */ 0807 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code); 0808 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code); 0809 0810 /* Build the bit length tree: */ 0811 build_tree(s, (tree_desc *)(&(s->bl_desc))); 0812 /* opt_len now includes the length of the tree representations, except 0813 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. 0814 */ 0815 0816 /* Determine the number of bit length codes to send. The pkzip format 0817 * requires that at least 4 bit length codes be sent. (appnote.txt says 0818 * 3 but the actual value used is 4.) 0819 */ 0820 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { 0821 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break; 0822 } 0823 /* Update opt_len to include the bit length tree and counts */ 0824 s->opt_len += 3*(max_blindex+1) + 5+5+4; 0825 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", 0826 s->opt_len, s->static_len)); 0827 0828 return max_blindex; 0829 } 0830 0831 /* =========================================================================== 0832 * Send the header for a block using dynamic Huffman trees: the counts, the 0833 * lengths of the bit length codes, the literal tree and the distance tree. 0834 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. 0835 */ 0836 local void send_all_trees(s, lcodes, dcodes, blcodes) 0837 deflate_state *s; 0838 int lcodes, dcodes, blcodes; /* number of codes for each tree */ 0839 { 0840 int rank; /* index in bl_order */ 0841 0842 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); 0843 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, 0844 "too many codes"); 0845 Tracev((stderr, "\nbl counts: ")); 0846 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */ 0847 send_bits(s, dcodes-1, 5); 0848 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */ 0849 for (rank = 0; rank < blcodes; rank++) { 0850 Tracev((stderr, "\nbl code %2d ", bl_order[rank])); 0851 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3); 0852 } 0853 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent)); 0854 0855 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */ 0856 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent)); 0857 0858 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */ 0859 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent)); 0860 } 0861 0862 /* =========================================================================== 0863 * Send a stored block 0864 */ 0865 void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last) 0866 deflate_state *s; 0867 charf *buf; /* input block */ 0868 ulg stored_len; /* length of input block */ 0869 int last; /* one if this is the last block for a file */ 0870 { 0871 send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */ 0872 #ifdef DEBUG 0873 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L; 0874 s->compressed_len += (stored_len + 4) << 3; 0875 #endif 0876 copy_block(s, buf, (unsigned)stored_len, 1); /* with header */ 0877 } 0878 0879 /* =========================================================================== 0880 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits) 0881 */ 0882 void ZLIB_INTERNAL _tr_flush_bits(s) 0883 deflate_state *s; 0884 { 0885 bi_flush(s); 0886 } 0887 0888 /* =========================================================================== 0889 * Send one empty static block to give enough lookahead for inflate. 0890 * This takes 10 bits, of which 7 may remain in the bit buffer. 0891 */ 0892 void ZLIB_INTERNAL _tr_align(s) 0893 deflate_state *s; 0894 { 0895 send_bits(s, STATIC_TREES<<1, 3); 0896 send_code(s, END_BLOCK, static_ltree); 0897 #ifdef DEBUG 0898 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ 0899 #endif 0900 bi_flush(s); 0901 } 0902 0903 /* =========================================================================== 0904 * Determine the best encoding for the current block: dynamic trees, static 0905 * trees or store, and output the encoded block to the zip file. 0906 */ 0907 void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last) 0908 deflate_state *s; 0909 charf *buf; /* input block, or NULL if too old */ 0910 ulg stored_len; /* length of input block */ 0911 int last; /* one if this is the last block for a file */ 0912 { 0913 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ 0914 int max_blindex = 0; /* index of last bit length code of non zero freq */ 0915 0916 /* Build the Huffman trees unless a stored block is forced */ 0917 if (s->level > 0) { 0918 0919 /* Check if the file is binary or text */ 0920 if (s->strm->data_type == Z_UNKNOWN) 0921 s->strm->data_type = detect_data_type(s); 0922 0923 /* Construct the literal and distance trees */ 0924 build_tree(s, (tree_desc *)(&(s->l_desc))); 0925 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len, 0926 s->static_len)); 0927 0928 build_tree(s, (tree_desc *)(&(s->d_desc))); 0929 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len, 0930 s->static_len)); 0931 /* At this point, opt_len and static_len are the total bit lengths of 0932 * the compressed block data, excluding the tree representations. 0933 */ 0934 0935 /* Build the bit length tree for the above two trees, and get the index 0936 * in bl_order of the last bit length code to send. 0937 */ 0938 max_blindex = build_bl_tree(s); 0939 0940 /* Determine the best encoding. Compute the block lengths in bytes. */ 0941 opt_lenb = (s->opt_len+3+7)>>3; 0942 static_lenb = (s->static_len+3+7)>>3; 0943 0944 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ", 0945 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, 0946 s->last_lit)); 0947 0948 if (static_lenb <= opt_lenb) opt_lenb = static_lenb; 0949 0950 } else { 0951 Assert(buf != (char*)0, "lost buf"); 0952 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */ 0953 } 0954 0955 #ifdef FORCE_STORED 0956 if (buf != (char*)0) { /* force stored block */ 0957 #else 0958 if (stored_len+4 <= opt_lenb && buf != (char*)0) { 0959 /* 4: two words for the lengths */ 0960 #endif 0961 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. 0962 * Otherwise we can't have processed more than WSIZE input bytes since 0963 * the last block flush, because compression would have been 0964 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to 0965 * transform a block into a stored block. 0966 */ 0967 _tr_stored_block(s, buf, stored_len, last); 0968 0969 #ifdef FORCE_STATIC 0970 } else if (static_lenb >= 0) { /* force static trees */ 0971 #else 0972 } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) { 0973 #endif 0974 send_bits(s, (STATIC_TREES<<1)+last, 3); 0975 compress_block(s, (const ct_data *)static_ltree, 0976 (const ct_data *)static_dtree); 0977 #ifdef DEBUG 0978 s->compressed_len += 3 + s->static_len; 0979 #endif 0980 } else { 0981 send_bits(s, (DYN_TREES<<1)+last, 3); 0982 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1, 0983 max_blindex+1); 0984 compress_block(s, (const ct_data *)s->dyn_ltree, 0985 (const ct_data *)s->dyn_dtree); 0986 #ifdef DEBUG 0987 s->compressed_len += 3 + s->opt_len; 0988 #endif 0989 } 0990 Assert (s->compressed_len == s->bits_sent, "bad compressed size"); 0991 /* The above check is made mod 2^32, for files larger than 512 MB 0992 * and uLong implemented on 32 bits. 0993 */ 0994 init_block(s); 0995 0996 if (last) { 0997 bi_windup(s); 0998 #ifdef DEBUG 0999 s->compressed_len += 7; /* align on byte boundary */ 1000 #endif 1001 } 1002 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3, 1003 s->compressed_len-7*last)); 1004 } 1005 1006 /* =========================================================================== 1007 * Save the match info and tally the frequency counts. Return true if 1008 * the current block must be flushed. 1009 */ 1010 int ZLIB_INTERNAL _tr_tally (s, dist, lc) 1011 deflate_state *s; 1012 unsigned dist; /* distance of matched string */ 1013 unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ 1014 { 1015 s->d_buf[s->last_lit] = (ush)dist; 1016 s->l_buf[s->last_lit++] = (uch)lc; 1017 if (dist == 0) { 1018 /* lc is the unmatched char */ 1019 s->dyn_ltree[lc].Freq++; 1020 } else { 1021 s->matches++; 1022 /* Here, lc is the match length - MIN_MATCH */ 1023 dist--; /* dist = match distance - 1 */ 1024 Assert((ush)dist < (ush)MAX_DIST(s) && 1025 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && 1026 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match"); 1027 1028 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++; 1029 s->dyn_dtree[d_code(dist)].Freq++; 1030 } 1031 1032 #ifdef TRUNCATE_BLOCK 1033 /* Try to guess if it is profitable to stop the current block here */ 1034 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) { 1035 /* Compute an upper bound for the compressed length */ 1036 ulg out_length = (ulg)s->last_lit*8L; 1037 ulg in_length = (ulg)((long)s->strstart - s->block_start); 1038 int dcode; 1039 for (dcode = 0; dcode < D_CODES; dcode++) { 1040 out_length += (ulg)s->dyn_dtree[dcode].Freq * 1041 (5L+extra_dbits[dcode]); 1042 } 1043 out_length >>= 3; 1044 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ", 1045 s->last_lit, in_length, out_length, 1046 100L - out_length*100L/in_length)); 1047 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1; 1048 } 1049 #endif 1050 return (s->last_lit == s->lit_bufsize-1); 1051 /* We avoid equality with lit_bufsize because of wraparound at 64K 1052 * on 16 bit machines and because stored blocks are restricted to 1053 * 64K-1 bytes. 1054 */ 1055 } 1056 1057 /* =========================================================================== 1058 * Send the block data compressed using the given Huffman trees 1059 */ 1060 local void compress_block(s, ltree, dtree) 1061 deflate_state *s; 1062 const ct_data *ltree; /* literal tree */ 1063 const ct_data *dtree; /* distance tree */ 1064 { 1065 unsigned dist; /* distance of matched string */ 1066 int lc; /* match length or unmatched char (if dist == 0) */ 1067 unsigned lx = 0; /* running index in l_buf */ 1068 unsigned code; /* the code to send */ 1069 int extra; /* number of extra bits to send */ 1070 1071 if (s->last_lit != 0) do { 1072 dist = s->d_buf[lx]; 1073 lc = s->l_buf[lx++]; 1074 if (dist == 0) { 1075 send_code(s, lc, ltree); /* send a literal byte */ 1076 Tracecv(isgraph(lc), (stderr," '%c' ", lc)); 1077 } else { 1078 /* Here, lc is the match length - MIN_MATCH */ 1079 code = _length_code[lc]; 1080 send_code(s, code+LITERALS+1, ltree); /* send the length code */ 1081 extra = extra_lbits[code]; 1082 if (extra != 0) { 1083 lc -= base_length[code]; 1084 send_bits(s, lc, extra); /* send the extra length bits */ 1085 } 1086 dist--; /* dist is now the match distance - 1 */ 1087 code = d_code(dist); 1088 Assert (code < D_CODES, "bad d_code"); 1089 1090 send_code(s, code, dtree); /* send the distance code */ 1091 extra = extra_dbits[code]; 1092 if (extra != 0) { 1093 dist -= base_dist[code]; 1094 send_bits(s, dist, extra); /* send the extra distance bits */ 1095 } 1096 } /* literal or match pair ? */ 1097 1098 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */ 1099 Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx, 1100 "pendingBuf overflow"); 1101 1102 } while (lx < s->last_lit); 1103 1104 send_code(s, END_BLOCK, ltree); 1105 } 1106 1107 /* =========================================================================== 1108 * Check if the data type is TEXT or BINARY, using the following algorithm: 1109 * - TEXT if the two conditions below are satisfied: 1110 * a) There are no non-portable control characters belonging to the 1111 * "black list" (0..6, 14..25, 28..31). 1112 * b) There is at least one printable character belonging to the 1113 * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255). 1114 * - BINARY otherwise. 1115 * - The following partially-portable control characters form a 1116 * "gray list" that is ignored in this detection algorithm: 1117 * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}). 1118 * IN assertion: the fields Freq of dyn_ltree are set. 1119 */ 1120 local int detect_data_type(s) 1121 deflate_state *s; 1122 { 1123 /* black_mask is the bit mask of black-listed bytes 1124 * set bits 0..6, 14..25, and 28..31 1125 * 0xf3ffc07f = binary 11110011111111111100000001111111 1126 */ 1127 unsigned long black_mask = 0xf3ffc07fUL; 1128 int n; 1129 1130 /* Check for non-textual ("black-listed") bytes. */ 1131 for (n = 0; n <= 31; n++, black_mask >>= 1) 1132 if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0)) 1133 return Z_BINARY; 1134 1135 /* Check for textual ("white-listed") bytes. */ 1136 if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0 1137 || s->dyn_ltree[13].Freq != 0) 1138 return Z_TEXT; 1139 for (n = 32; n < LITERALS; n++) 1140 if (s->dyn_ltree[n].Freq != 0) 1141 return Z_TEXT; 1142 1143 /* There are no "black-listed" or "white-listed" bytes: 1144 * this stream either is empty or has tolerated ("gray-listed") bytes only. 1145 */ 1146 return Z_BINARY; 1147 } 1148 1149 /* =========================================================================== 1150 * Reverse the first len bits of a code, using straightforward code (a faster 1151 * method would use a table) 1152 * IN assertion: 1 <= len <= 15 1153 */ 1154 local unsigned bi_reverse(code, len) 1155 unsigned code; /* the value to invert */ 1156 int len; /* its bit length */ 1157 { 1158 register unsigned res = 0; 1159 do { 1160 res |= code & 1; 1161 code >>= 1, res <<= 1; 1162 } while (--len > 0); 1163 return res >> 1; 1164 } 1165 1166 /* =========================================================================== 1167 * Flush the bit buffer, keeping at most 7 bits in it. 1168 */ 1169 local void bi_flush(s) 1170 deflate_state *s; 1171 { 1172 if (s->bi_valid == 16) { 1173 put_short(s, s->bi_buf); 1174 s->bi_buf = 0; 1175 s->bi_valid = 0; 1176 } else if (s->bi_valid >= 8) { 1177 put_byte(s, (Byte)s->bi_buf); 1178 s->bi_buf >>= 8; 1179 s->bi_valid -= 8; 1180 } 1181 } 1182 1183 /* =========================================================================== 1184 * Flush the bit buffer and align the output on a byte boundary 1185 */ 1186 local void bi_windup(s) 1187 deflate_state *s; 1188 { 1189 if (s->bi_valid > 8) { 1190 put_short(s, s->bi_buf); 1191 } else if (s->bi_valid > 0) { 1192 put_byte(s, (Byte)s->bi_buf); 1193 } 1194 s->bi_buf = 0; 1195 s->bi_valid = 0; 1196 #ifdef DEBUG 1197 s->bits_sent = (s->bits_sent+7) & ~7; 1198 #endif 1199 } 1200 1201 /* =========================================================================== 1202 * Copy a stored block, storing first the length and its 1203 * one's complement if requested. 1204 */ 1205 local void copy_block(s, buf, len, header) 1206 deflate_state *s; 1207 charf *buf; /* the input data */ 1208 unsigned len; /* its length */ 1209 int header; /* true if block header must be written */ 1210 { 1211 bi_windup(s); /* align on byte boundary */ 1212 1213 if (header) { 1214 put_short(s, (ush)len); 1215 put_short(s, (ush)~len); 1216 #ifdef DEBUG 1217 s->bits_sent += 2*16; 1218 #endif 1219 } 1220 #ifdef DEBUG 1221 s->bits_sent += (ulg)len<<3; 1222 #endif 1223 while (len--) { 1224 put_byte(s, *buf++); 1225 } 1226 }