Jonathon Fletcher
Basic gzip/gunzip in memory buffer examples using zlib code.
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trees.c
00001 /* trees.c -- output deflated data using Huffman coding 00002 * Copyright (C) 1995-2012 Jean-loup Gailly 00003 * detect_data_type() function provided freely by Cosmin Truta, 2006 00004 * For conditions of distribution and use, see copyright notice in zlib.h 00005 */ 00006 00007 /* 00008 * ALGORITHM 00009 * 00010 * The "deflation" process uses several Huffman trees. The more 00011 * common source values are represented by shorter bit sequences. 00012 * 00013 * Each code tree is stored in a compressed form which is itself 00014 * a Huffman encoding of the lengths of all the code strings (in 00015 * ascending order by source values). The actual code strings are 00016 * reconstructed from the lengths in the inflate process, as described 00017 * in the deflate specification. 00018 * 00019 * REFERENCES 00020 * 00021 * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification". 00022 * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc 00023 * 00024 * Storer, James A. 00025 * Data Compression: Methods and Theory, pp. 49-50. 00026 * Computer Science Press, 1988. ISBN 0-7167-8156-5. 00027 * 00028 * Sedgewick, R. 00029 * Algorithms, p290. 00030 * Addison-Wesley, 1983. ISBN 0-201-06672-6. 00031 */ 00032 00033 /* @(#) $Id$ */ 00034 00035 /* #define GEN_TREES_H */ 00036 00037 #include "deflate.h" 00038 00039 #ifdef DEBUG 00040 # include <ctype.h> 00041 #endif 00042 00043 /* =========================================================================== 00044 * Constants 00045 */ 00046 00047 #define MAX_BL_BITS 7 00048 /* Bit length codes must not exceed MAX_BL_BITS bits */ 00049 00050 #define END_BLOCK 256 00051 /* end of block literal code */ 00052 00053 #define REP_3_6 16 00054 /* repeat previous bit length 3-6 times (2 bits of repeat count) */ 00055 00056 #define REPZ_3_10 17 00057 /* repeat a zero length 3-10 times (3 bits of repeat count) */ 00058 00059 #define REPZ_11_138 18 00060 /* repeat a zero length 11-138 times (7 bits of repeat count) */ 00061 00062 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ 00063 = {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}; 00064 00065 local const int extra_dbits[D_CODES] /* extra bits for each distance code */ 00066 = {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}; 00067 00068 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */ 00069 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; 00070 00071 local const uch bl_order[BL_CODES] 00072 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; 00073 /* The lengths of the bit length codes are sent in order of decreasing 00074 * probability, to avoid transmitting the lengths for unused bit length codes. 00075 */ 00076 00077 /* =========================================================================== 00078 * Local data. These are initialized only once. 00079 */ 00080 00081 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */ 00082 00083 #if defined(GEN_TREES_H) || !defined(STDC) 00084 /* non ANSI compilers may not accept trees.h */ 00085 00086 local ct_data static_ltree[L_CODES+2]; 00087 /* The static literal tree. Since the bit lengths are imposed, there is no 00088 * need for the L_CODES extra codes used during heap construction. However 00089 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init 00090 * below). 00091 */ 00092 00093 local ct_data static_dtree[D_CODES]; 00094 /* The static distance tree. (Actually a trivial tree since all codes use 00095 * 5 bits.) 00096 */ 00097 00098 uch _dist_code[DIST_CODE_LEN]; 00099 /* Distance codes. The first 256 values correspond to the distances 00100 * 3 .. 258, the last 256 values correspond to the top 8 bits of 00101 * the 15 bit distances. 00102 */ 00103 00104 uch _length_code[MAX_MATCH-MIN_MATCH+1]; 00105 /* length code for each normalized match length (0 == MIN_MATCH) */ 00106 00107 local int base_length[LENGTH_CODES]; 00108 /* First normalized length for each code (0 = MIN_MATCH) */ 00109 00110 local int base_dist[D_CODES]; 00111 /* First normalized distance for each code (0 = distance of 1) */ 00112 00113 #else 00114 # include "trees.h" 00115 #endif /* GEN_TREES_H */ 00116 00117 struct static_tree_desc_s { 00118 const ct_data *static_tree; /* static tree or NULL */ 00119 const intf *extra_bits; /* extra bits for each code or NULL */ 00120 int extra_base; /* base index for extra_bits */ 00121 int elems; /* max number of elements in the tree */ 00122 int max_length; /* max bit length for the codes */ 00123 }; 00124 00125 local static_tree_desc static_l_desc = 00126 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; 00127 00128 local static_tree_desc static_d_desc = 00129 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; 00130 00131 local static_tree_desc static_bl_desc = 00132 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; 00133 00134 /* =========================================================================== 00135 * Local (static) routines in this file. 00136 */ 00137 00138 local void tr_static_init OF((void)); 00139 local void init_block OF((deflate_state *s)); 00140 local void pqdownheap OF((deflate_state *s, ct_data *tree, int k)); 00141 local void gen_bitlen OF((deflate_state *s, tree_desc *desc)); 00142 local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count)); 00143 local void build_tree OF((deflate_state *s, tree_desc *desc)); 00144 local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code)); 00145 local void send_tree OF((deflate_state *s, ct_data *tree, int max_code)); 00146 local int build_bl_tree OF((deflate_state *s)); 00147 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes, 00148 int blcodes)); 00149 local void compress_block OF((deflate_state *s, ct_data *ltree, 00150 ct_data *dtree)); 00151 local int detect_data_type OF((deflate_state *s)); 00152 local unsigned bi_reverse OF((unsigned value, int length)); 00153 local void bi_windup OF((deflate_state *s)); 00154 local void bi_flush OF((deflate_state *s)); 00155 local void copy_block OF((deflate_state *s, charf *buf, unsigned len, 00156 int header)); 00157 00158 #ifdef GEN_TREES_H 00159 local void gen_trees_header OF((void)); 00160 #endif 00161 00162 #ifndef DEBUG 00163 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len) 00164 /* Send a code of the given tree. c and tree must not have side effects */ 00165 00166 #else /* DEBUG */ 00167 # define send_code(s, c, tree) \ 00168 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \ 00169 send_bits(s, tree[c].Code, tree[c].Len); } 00170 #endif 00171 00172 /* =========================================================================== 00173 * Output a short LSB first on the stream. 00174 * IN assertion: there is enough room in pendingBuf. 00175 */ 00176 #define put_short(s, w) { \ 00177 put_byte(s, (uch)((w) & 0xff)); \ 00178 put_byte(s, (uch)((ush)(w) >> 8)); \ 00179 } 00180 00181 /* =========================================================================== 00182 * Send a value on a given number of bits. 00183 * IN assertion: length <= 16 and value fits in length bits. 00184 */ 00185 #ifdef DEBUG 00186 local void send_bits OF((deflate_state *s, int value, int length)); 00187 00188 local void send_bits(s, value, length) 00189 deflate_state *s; 00190 int value; /* value to send */ 00191 int length; /* number of bits */ 00192 { 00193 Tracevv((stderr," l %2d v %4x ", length, value)); 00194 Assert(length > 0 && length <= 15, "invalid length"); 00195 s->bits_sent += (ulg)length; 00196 00197 /* If not enough room in bi_buf, use (valid) bits from bi_buf and 00198 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid)) 00199 * unused bits in value. 00200 */ 00201 if (s->bi_valid > (int)Buf_size - length) { 00202 s->bi_buf |= (ush)value << s->bi_valid; 00203 put_short(s, s->bi_buf); 00204 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid); 00205 s->bi_valid += length - Buf_size; 00206 } else { 00207 s->bi_buf |= (ush)value << s->bi_valid; 00208 s->bi_valid += length; 00209 } 00210 } 00211 #else /* !DEBUG */ 00212 00213 #define send_bits(s, value, length) \ 00214 { int len = length;\ 00215 if (s->bi_valid > (int)Buf_size - len) {\ 00216 int val = value;\ 00217 s->bi_buf |= (ush)val << s->bi_valid;\ 00218 put_short(s, s->bi_buf);\ 00219 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\ 00220 s->bi_valid += len - Buf_size;\ 00221 } else {\ 00222 s->bi_buf |= (ush)(value) << s->bi_valid;\ 00223 s->bi_valid += len;\ 00224 }\ 00225 } 00226 #endif /* DEBUG */ 00227 00228 00229 /* the arguments must not have side effects */ 00230 00231 /* =========================================================================== 00232 * Initialize the various 'constant' tables. 00233 */ 00234 local void tr_static_init() 00235 { 00236 #if defined(GEN_TREES_H) || !defined(STDC) 00237 static int static_init_done = 0; 00238 int n; /* iterates over tree elements */ 00239 int bits; /* bit counter */ 00240 int length; /* length value */ 00241 int code; /* code value */ 00242 int dist; /* distance index */ 00243 ush bl_count[MAX_BITS+1]; 00244 /* number of codes at each bit length for an optimal tree */ 00245 00246 if (static_init_done) return; 00247 00248 /* For some embedded targets, global variables are not initialized: */ 00249 #ifdef NO_INIT_GLOBAL_POINTERS 00250 static_l_desc.static_tree = static_ltree; 00251 static_l_desc.extra_bits = extra_lbits; 00252 static_d_desc.static_tree = static_dtree; 00253 static_d_desc.extra_bits = extra_dbits; 00254 static_bl_desc.extra_bits = extra_blbits; 00255 #endif 00256 00257 /* Initialize the mapping length (0..255) -> length code (0..28) */ 00258 length = 0; 00259 for (code = 0; code < LENGTH_CODES-1; code++) { 00260 base_length[code] = length; 00261 for (n = 0; n < (1<<extra_lbits[code]); n++) { 00262 _length_code[length++] = (uch)code; 00263 } 00264 } 00265 Assert (length == 256, "tr_static_init: length != 256"); 00266 /* Note that the length 255 (match length 258) can be represented 00267 * in two different ways: code 284 + 5 bits or code 285, so we 00268 * overwrite length_code[255] to use the best encoding: 00269 */ 00270 _length_code[length-1] = (uch)code; 00271 00272 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ 00273 dist = 0; 00274 for (code = 0 ; code < 16; code++) { 00275 base_dist[code] = dist; 00276 for (n = 0; n < (1<<extra_dbits[code]); n++) { 00277 _dist_code[dist++] = (uch)code; 00278 } 00279 } 00280 Assert (dist == 256, "tr_static_init: dist != 256"); 00281 dist >>= 7; /* from now on, all distances are divided by 128 */ 00282 for ( ; code < D_CODES; code++) { 00283 base_dist[code] = dist << 7; 00284 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { 00285 _dist_code[256 + dist++] = (uch)code; 00286 } 00287 } 00288 Assert (dist == 256, "tr_static_init: 256+dist != 512"); 00289 00290 /* Construct the codes of the static literal tree */ 00291 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; 00292 n = 0; 00293 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; 00294 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; 00295 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; 00296 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; 00297 /* Codes 286 and 287 do not exist, but we must include them in the 00298 * tree construction to get a canonical Huffman tree (longest code 00299 * all ones) 00300 */ 00301 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count); 00302 00303 /* The static distance tree is trivial: */ 00304 for (n = 0; n < D_CODES; n++) { 00305 static_dtree[n].Len = 5; 00306 static_dtree[n].Code = bi_reverse((unsigned)n, 5); 00307 } 00308 static_init_done = 1; 00309 00310 # ifdef GEN_TREES_H 00311 gen_trees_header(); 00312 # endif 00313 #endif /* defined(GEN_TREES_H) || !defined(STDC) */ 00314 } 00315 00316 /* =========================================================================== 00317 * Genererate the file trees.h describing the static trees. 00318 */ 00319 #ifdef GEN_TREES_H 00320 # ifndef DEBUG 00321 # include <stdio.h> 00322 # endif 00323 00324 # define SEPARATOR(i, last, width) \ 00325 ((i) == (last)? "\n};\n\n" : \ 00326 ((i) % (width) == (width)-1 ? ",\n" : ", ")) 00327 00328 void gen_trees_header() 00329 { 00330 FILE *header = fopen("trees.h", "w"); 00331 int i; 00332 00333 Assert (header != NULL, "Can't open trees.h"); 00334 fprintf(header, 00335 "/* header created automatically with -DGEN_TREES_H */\n\n"); 00336 00337 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n"); 00338 for (i = 0; i < L_CODES+2; i++) { 00339 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code, 00340 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5)); 00341 } 00342 00343 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n"); 00344 for (i = 0; i < D_CODES; i++) { 00345 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code, 00346 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5)); 00347 } 00348 00349 fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n"); 00350 for (i = 0; i < DIST_CODE_LEN; i++) { 00351 fprintf(header, "%2u%s", _dist_code[i], 00352 SEPARATOR(i, DIST_CODE_LEN-1, 20)); 00353 } 00354 00355 fprintf(header, 00356 "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n"); 00357 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) { 00358 fprintf(header, "%2u%s", _length_code[i], 00359 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20)); 00360 } 00361 00362 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n"); 00363 for (i = 0; i < LENGTH_CODES; i++) { 00364 fprintf(header, "%1u%s", base_length[i], 00365 SEPARATOR(i, LENGTH_CODES-1, 20)); 00366 } 00367 00368 fprintf(header, "local const int base_dist[D_CODES] = {\n"); 00369 for (i = 0; i < D_CODES; i++) { 00370 fprintf(header, "%5u%s", base_dist[i], 00371 SEPARATOR(i, D_CODES-1, 10)); 00372 } 00373 00374 fclose(header); 00375 } 00376 #endif /* GEN_TREES_H */ 00377 00378 /* =========================================================================== 00379 * Initialize the tree data structures for a new zlib stream. 00380 */ 00381 void ZLIB_INTERNAL _tr_init(s) 00382 deflate_state *s; 00383 { 00384 tr_static_init(); 00385 00386 s->l_desc.dyn_tree = s->dyn_ltree; 00387 s->l_desc.stat_desc = &static_l_desc; 00388 00389 s->d_desc.dyn_tree = s->dyn_dtree; 00390 s->d_desc.stat_desc = &static_d_desc; 00391 00392 s->bl_desc.dyn_tree = s->bl_tree; 00393 s->bl_desc.stat_desc = &static_bl_desc; 00394 00395 s->bi_buf = 0; 00396 s->bi_valid = 0; 00397 #ifdef DEBUG 00398 s->compressed_len = 0L; 00399 s->bits_sent = 0L; 00400 #endif 00401 00402 /* Initialize the first block of the first file: */ 00403 init_block(s); 00404 } 00405 00406 /* =========================================================================== 00407 * Initialize a new block. 00408 */ 00409 local void init_block(s) 00410 deflate_state *s; 00411 { 00412 int n; /* iterates over tree elements */ 00413 00414 /* Initialize the trees. */ 00415 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0; 00416 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0; 00417 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0; 00418 00419 s->dyn_ltree[END_BLOCK].Freq = 1; 00420 s->opt_len = s->static_len = 0L; 00421 s->last_lit = s->matches = 0; 00422 } 00423 00424 #define SMALLEST 1 00425 /* Index within the heap array of least frequent node in the Huffman tree */ 00426 00427 00428 /* =========================================================================== 00429 * Remove the smallest element from the heap and recreate the heap with 00430 * one less element. Updates heap and heap_len. 00431 */ 00432 #define pqremove(s, tree, top) \ 00433 {\ 00434 top = s->heap[SMALLEST]; \ 00435 s->heap[SMALLEST] = s->heap[s->heap_len--]; \ 00436 pqdownheap(s, tree, SMALLEST); \ 00437 } 00438 00439 /* =========================================================================== 00440 * Compares to subtrees, using the tree depth as tie breaker when 00441 * the subtrees have equal frequency. This minimizes the worst case length. 00442 */ 00443 #define smaller(tree, n, m, depth) \ 00444 (tree[n].Freq < tree[m].Freq || \ 00445 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) 00446 00447 /* =========================================================================== 00448 * Restore the heap property by moving down the tree starting at node k, 00449 * exchanging a node with the smallest of its two sons if necessary, stopping 00450 * when the heap property is re-established (each father smaller than its 00451 * two sons). 00452 */ 00453 local void pqdownheap(s, tree, k) 00454 deflate_state *s; 00455 ct_data *tree; /* the tree to restore */ 00456 int k; /* node to move down */ 00457 { 00458 int v = s->heap[k]; 00459 int j = k << 1; /* left son of k */ 00460 while (j <= s->heap_len) { 00461 /* Set j to the smallest of the two sons: */ 00462 if (j < s->heap_len && 00463 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { 00464 j++; 00465 } 00466 /* Exit if v is smaller than both sons */ 00467 if (smaller(tree, v, s->heap[j], s->depth)) break; 00468 00469 /* Exchange v with the smallest son */ 00470 s->heap[k] = s->heap[j]; k = j; 00471 00472 /* And continue down the tree, setting j to the left son of k */ 00473 j <<= 1; 00474 } 00475 s->heap[k] = v; 00476 } 00477 00478 /* =========================================================================== 00479 * Compute the optimal bit lengths for a tree and update the total bit length 00480 * for the current block. 00481 * IN assertion: the fields freq and dad are set, heap[heap_max] and 00482 * above are the tree nodes sorted by increasing frequency. 00483 * OUT assertions: the field len is set to the optimal bit length, the 00484 * array bl_count contains the frequencies for each bit length. 00485 * The length opt_len is updated; static_len is also updated if stree is 00486 * not null. 00487 */ 00488 local void gen_bitlen(s, desc) 00489 deflate_state *s; 00490 tree_desc *desc; /* the tree descriptor */ 00491 { 00492 ct_data *tree = desc->dyn_tree; 00493 int max_code = desc->max_code; 00494 const ct_data *stree = desc->stat_desc->static_tree; 00495 const intf *extra = desc->stat_desc->extra_bits; 00496 int base = desc->stat_desc->extra_base; 00497 int max_length = desc->stat_desc->max_length; 00498 int h; /* heap index */ 00499 int n, m; /* iterate over the tree elements */ 00500 int bits; /* bit length */ 00501 int xbits; /* extra bits */ 00502 ush f; /* frequency */ 00503 int overflow = 0; /* number of elements with bit length too large */ 00504 00505 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0; 00506 00507 /* In a first pass, compute the optimal bit lengths (which may 00508 * overflow in the case of the bit length tree). 00509 */ 00510 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ 00511 00512 for (h = s->heap_max+1; h < HEAP_SIZE; h++) { 00513 n = s->heap[h]; 00514 bits = tree[tree[n].Dad].Len + 1; 00515 if (bits > max_length) bits = max_length, overflow++; 00516 tree[n].Len = (ush)bits; 00517 /* We overwrite tree[n].Dad which is no longer needed */ 00518 00519 if (n > max_code) continue; /* not a leaf node */ 00520 00521 s->bl_count[bits]++; 00522 xbits = 0; 00523 if (n >= base) xbits = extra[n-base]; 00524 f = tree[n].Freq; 00525 s->opt_len += (ulg)f * (bits + xbits); 00526 if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits); 00527 } 00528 if (overflow == 0) return; 00529 00530 Trace((stderr,"\nbit length overflow\n")); 00531 /* This happens for example on obj2 and pic of the Calgary corpus */ 00532 00533 /* Find the first bit length which could increase: */ 00534 do { 00535 bits = max_length-1; 00536 while (s->bl_count[bits] == 0) bits--; 00537 s->bl_count[bits]--; /* move one leaf down the tree */ 00538 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */ 00539 s->bl_count[max_length]--; 00540 /* The brother of the overflow item also moves one step up, 00541 * but this does not affect bl_count[max_length] 00542 */ 00543 overflow -= 2; 00544 } while (overflow > 0); 00545 00546 /* Now recompute all bit lengths, scanning in increasing frequency. 00547 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all 00548 * lengths instead of fixing only the wrong ones. This idea is taken 00549 * from 'ar' written by Haruhiko Okumura.) 00550 */ 00551 for (bits = max_length; bits != 0; bits--) { 00552 n = s->bl_count[bits]; 00553 while (n != 0) { 00554 m = s->heap[--h]; 00555 if (m > max_code) continue; 00556 if ((unsigned) tree[m].Len != (unsigned) bits) { 00557 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); 00558 s->opt_len += ((long)bits - (long)tree[m].Len) 00559 *(long)tree[m].Freq; 00560 tree[m].Len = (ush)bits; 00561 } 00562 n--; 00563 } 00564 } 00565 } 00566 00567 /* =========================================================================== 00568 * Generate the codes for a given tree and bit counts (which need not be 00569 * optimal). 00570 * IN assertion: the array bl_count contains the bit length statistics for 00571 * the given tree and the field len is set for all tree elements. 00572 * OUT assertion: the field code is set for all tree elements of non 00573 * zero code length. 00574 */ 00575 local void gen_codes (tree, max_code, bl_count) 00576 ct_data *tree; /* the tree to decorate */ 00577 int max_code; /* largest code with non zero frequency */ 00578 ushf *bl_count; /* number of codes at each bit length */ 00579 { 00580 ush next_code[MAX_BITS+1]; /* next code value for each bit length */ 00581 ush code = 0; /* running code value */ 00582 int bits; /* bit index */ 00583 int n; /* code index */ 00584 00585 /* The distribution counts are first used to generate the code values 00586 * without bit reversal. 00587 */ 00588 for (bits = 1; bits <= MAX_BITS; bits++) { 00589 next_code[bits] = code = (code + bl_count[bits-1]) << 1; 00590 } 00591 /* Check that the bit counts in bl_count are consistent. The last code 00592 * must be all ones. 00593 */ 00594 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, 00595 "inconsistent bit counts"); 00596 Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); 00597 00598 for (n = 0; n <= max_code; n++) { 00599 int len = tree[n].Len; 00600 if (len == 0) continue; 00601 /* Now reverse the bits */ 00602 tree[n].Code = bi_reverse(next_code[len]++, len); 00603 00604 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", 00605 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); 00606 } 00607 } 00608 00609 /* =========================================================================== 00610 * Construct one Huffman tree and assigns the code bit strings and lengths. 00611 * Update the total bit length for the current block. 00612 * IN assertion: the field freq is set for all tree elements. 00613 * OUT assertions: the fields len and code are set to the optimal bit length 00614 * and corresponding code. The length opt_len is updated; static_len is 00615 * also updated if stree is not null. The field max_code is set. 00616 */ 00617 local void build_tree(s, desc) 00618 deflate_state *s; 00619 tree_desc *desc; /* the tree descriptor */ 00620 { 00621 ct_data *tree = desc->dyn_tree; 00622 const ct_data *stree = desc->stat_desc->static_tree; 00623 int elems = desc->stat_desc->elems; 00624 int n, m; /* iterate over heap elements */ 00625 int max_code = -1; /* largest code with non zero frequency */ 00626 int node; /* new node being created */ 00627 00628 /* Construct the initial heap, with least frequent element in 00629 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. 00630 * heap[0] is not used. 00631 */ 00632 s->heap_len = 0, s->heap_max = HEAP_SIZE; 00633 00634 for (n = 0; n < elems; n++) { 00635 if (tree[n].Freq != 0) { 00636 s->heap[++(s->heap_len)] = max_code = n; 00637 s->depth[n] = 0; 00638 } else { 00639 tree[n].Len = 0; 00640 } 00641 } 00642 00643 /* The pkzip format requires that at least one distance code exists, 00644 * and that at least one bit should be sent even if there is only one 00645 * possible code. So to avoid special checks later on we force at least 00646 * two codes of non zero frequency. 00647 */ 00648 while (s->heap_len < 2) { 00649 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0); 00650 tree[node].Freq = 1; 00651 s->depth[node] = 0; 00652 s->opt_len--; if (stree) s->static_len -= stree[node].Len; 00653 /* node is 0 or 1 so it does not have extra bits */ 00654 } 00655 desc->max_code = max_code; 00656 00657 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, 00658 * establish sub-heaps of increasing lengths: 00659 */ 00660 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n); 00661 00662 /* Construct the Huffman tree by repeatedly combining the least two 00663 * frequent nodes. 00664 */ 00665 node = elems; /* next internal node of the tree */ 00666 do { 00667 pqremove(s, tree, n); /* n = node of least frequency */ 00668 m = s->heap[SMALLEST]; /* m = node of next least frequency */ 00669 00670 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */ 00671 s->heap[--(s->heap_max)] = m; 00672 00673 /* Create a new node father of n and m */ 00674 tree[node].Freq = tree[n].Freq + tree[m].Freq; 00675 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ? 00676 s->depth[n] : s->depth[m]) + 1); 00677 tree[n].Dad = tree[m].Dad = (ush)node; 00678 #ifdef DUMP_BL_TREE 00679 if (tree == s->bl_tree) { 00680 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", 00681 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); 00682 } 00683 #endif 00684 /* and insert the new node in the heap */ 00685 s->heap[SMALLEST] = node++; 00686 pqdownheap(s, tree, SMALLEST); 00687 00688 } while (s->heap_len >= 2); 00689 00690 s->heap[--(s->heap_max)] = s->heap[SMALLEST]; 00691 00692 /* At this point, the fields freq and dad are set. We can now 00693 * generate the bit lengths. 00694 */ 00695 gen_bitlen(s, (tree_desc *)desc); 00696 00697 /* The field len is now set, we can generate the bit codes */ 00698 gen_codes ((ct_data *)tree, max_code, s->bl_count); 00699 } 00700 00701 /* =========================================================================== 00702 * Scan a literal or distance tree to determine the frequencies of the codes 00703 * in the bit length tree. 00704 */ 00705 local void scan_tree (s, tree, max_code) 00706 deflate_state *s; 00707 ct_data *tree; /* the tree to be scanned */ 00708 int max_code; /* and its largest code of non zero frequency */ 00709 { 00710 int n; /* iterates over all tree elements */ 00711 int prevlen = -1; /* last emitted length */ 00712 int curlen; /* length of current code */ 00713 int nextlen = tree[0].Len; /* length of next code */ 00714 int count = 0; /* repeat count of the current code */ 00715 int max_count = 7; /* max repeat count */ 00716 int min_count = 4; /* min repeat count */ 00717 00718 if (nextlen == 0) max_count = 138, min_count = 3; 00719 tree[max_code+1].Len = (ush)0xffff; /* guard */ 00720 00721 for (n = 0; n <= max_code; n++) { 00722 curlen = nextlen; nextlen = tree[n+1].Len; 00723 if (++count < max_count && curlen == nextlen) { 00724 continue; 00725 } else if (count < min_count) { 00726 s->bl_tree[curlen].Freq += count; 00727 } else if (curlen != 0) { 00728 if (curlen != prevlen) s->bl_tree[curlen].Freq++; 00729 s->bl_tree[REP_3_6].Freq++; 00730 } else if (count <= 10) { 00731 s->bl_tree[REPZ_3_10].Freq++; 00732 } else { 00733 s->bl_tree[REPZ_11_138].Freq++; 00734 } 00735 count = 0; prevlen = curlen; 00736 if (nextlen == 0) { 00737 max_count = 138, min_count = 3; 00738 } else if (curlen == nextlen) { 00739 max_count = 6, min_count = 3; 00740 } else { 00741 max_count = 7, min_count = 4; 00742 } 00743 } 00744 } 00745 00746 /* =========================================================================== 00747 * Send a literal or distance tree in compressed form, using the codes in 00748 * bl_tree. 00749 */ 00750 local void send_tree (s, tree, max_code) 00751 deflate_state *s; 00752 ct_data *tree; /* the tree to be scanned */ 00753 int max_code; /* and its largest code of non zero frequency */ 00754 { 00755 int n; /* iterates over all tree elements */ 00756 int prevlen = -1; /* last emitted length */ 00757 int curlen; /* length of current code */ 00758 int nextlen = tree[0].Len; /* length of next code */ 00759 int count = 0; /* repeat count of the current code */ 00760 int max_count = 7; /* max repeat count */ 00761 int min_count = 4; /* min repeat count */ 00762 00763 /* tree[max_code+1].Len = -1; */ /* guard already set */ 00764 if (nextlen == 0) max_count = 138, min_count = 3; 00765 00766 for (n = 0; n <= max_code; n++) { 00767 curlen = nextlen; nextlen = tree[n+1].Len; 00768 if (++count < max_count && curlen == nextlen) { 00769 continue; 00770 } else if (count < min_count) { 00771 do { send_code(s, curlen, s->bl_tree); } while (--count != 0); 00772 00773 } else if (curlen != 0) { 00774 if (curlen != prevlen) { 00775 send_code(s, curlen, s->bl_tree); count--; 00776 } 00777 Assert(count >= 3 && count <= 6, " 3_6?"); 00778 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2); 00779 00780 } else if (count <= 10) { 00781 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3); 00782 00783 } else { 00784 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7); 00785 } 00786 count = 0; prevlen = curlen; 00787 if (nextlen == 0) { 00788 max_count = 138, min_count = 3; 00789 } else if (curlen == nextlen) { 00790 max_count = 6, min_count = 3; 00791 } else { 00792 max_count = 7, min_count = 4; 00793 } 00794 } 00795 } 00796 00797 /* =========================================================================== 00798 * Construct the Huffman tree for the bit lengths and return the index in 00799 * bl_order of the last bit length code to send. 00800 */ 00801 local int build_bl_tree(s) 00802 deflate_state *s; 00803 { 00804 int max_blindex; /* index of last bit length code of non zero freq */ 00805 00806 /* Determine the bit length frequencies for literal and distance trees */ 00807 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code); 00808 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code); 00809 00810 /* Build the bit length tree: */ 00811 build_tree(s, (tree_desc *)(&(s->bl_desc))); 00812 /* opt_len now includes the length of the tree representations, except 00813 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. 00814 */ 00815 00816 /* Determine the number of bit length codes to send. The pkzip format 00817 * requires that at least 4 bit length codes be sent. (appnote.txt says 00818 * 3 but the actual value used is 4.) 00819 */ 00820 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { 00821 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break; 00822 } 00823 /* Update opt_len to include the bit length tree and counts */ 00824 s->opt_len += 3*(max_blindex+1) + 5+5+4; 00825 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", 00826 s->opt_len, s->static_len)); 00827 00828 return max_blindex; 00829 } 00830 00831 /* =========================================================================== 00832 * Send the header for a block using dynamic Huffman trees: the counts, the 00833 * lengths of the bit length codes, the literal tree and the distance tree. 00834 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. 00835 */ 00836 local void send_all_trees(s, lcodes, dcodes, blcodes) 00837 deflate_state *s; 00838 int lcodes, dcodes, blcodes; /* number of codes for each tree */ 00839 { 00840 int rank; /* index in bl_order */ 00841 00842 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); 00843 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, 00844 "too many codes"); 00845 Tracev((stderr, "\nbl counts: ")); 00846 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */ 00847 send_bits(s, dcodes-1, 5); 00848 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */ 00849 for (rank = 0; rank < blcodes; rank++) { 00850 Tracev((stderr, "\nbl code %2d ", bl_order[rank])); 00851 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3); 00852 } 00853 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent)); 00854 00855 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */ 00856 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent)); 00857 00858 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */ 00859 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent)); 00860 } 00861 00862 /* =========================================================================== 00863 * Send a stored block 00864 */ 00865 void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last) 00866 deflate_state *s; 00867 charf *buf; /* input block */ 00868 ulg stored_len; /* length of input block */ 00869 int last; /* one if this is the last block for a file */ 00870 { 00871 send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */ 00872 #ifdef DEBUG 00873 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L; 00874 s->compressed_len += (stored_len + 4) << 3; 00875 #endif 00876 copy_block(s, buf, (unsigned)stored_len, 1); /* with header */ 00877 } 00878 00879 /* =========================================================================== 00880 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits) 00881 */ 00882 void ZLIB_INTERNAL _tr_flush_bits(s) 00883 deflate_state *s; 00884 { 00885 bi_flush(s); 00886 } 00887 00888 /* =========================================================================== 00889 * Send one empty static block to give enough lookahead for inflate. 00890 * This takes 10 bits, of which 7 may remain in the bit buffer. 00891 */ 00892 void ZLIB_INTERNAL _tr_align(s) 00893 deflate_state *s; 00894 { 00895 send_bits(s, STATIC_TREES<<1, 3); 00896 send_code(s, END_BLOCK, static_ltree); 00897 #ifdef DEBUG 00898 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ 00899 #endif 00900 bi_flush(s); 00901 } 00902 00903 /* =========================================================================== 00904 * Determine the best encoding for the current block: dynamic trees, static 00905 * trees or store, and output the encoded block to the zip file. 00906 */ 00907 void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last) 00908 deflate_state *s; 00909 charf *buf; /* input block, or NULL if too old */ 00910 ulg stored_len; /* length of input block */ 00911 int last; /* one if this is the last block for a file */ 00912 { 00913 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ 00914 int max_blindex = 0; /* index of last bit length code of non zero freq */ 00915 00916 /* Build the Huffman trees unless a stored block is forced */ 00917 if (s->level > 0) { 00918 00919 /* Check if the file is binary or text */ 00920 if (s->strm->data_type == Z_UNKNOWN) 00921 s->strm->data_type = detect_data_type(s); 00922 00923 /* Construct the literal and distance trees */ 00924 build_tree(s, (tree_desc *)(&(s->l_desc))); 00925 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len, 00926 s->static_len)); 00927 00928 build_tree(s, (tree_desc *)(&(s->d_desc))); 00929 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len, 00930 s->static_len)); 00931 /* At this point, opt_len and static_len are the total bit lengths of 00932 * the compressed block data, excluding the tree representations. 00933 */ 00934 00935 /* Build the bit length tree for the above two trees, and get the index 00936 * in bl_order of the last bit length code to send. 00937 */ 00938 max_blindex = build_bl_tree(s); 00939 00940 /* Determine the best encoding. Compute the block lengths in bytes. */ 00941 opt_lenb = (s->opt_len+3+7)>>3; 00942 static_lenb = (s->static_len+3+7)>>3; 00943 00944 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ", 00945 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, 00946 s->last_lit)); 00947 00948 if (static_lenb <= opt_lenb) opt_lenb = static_lenb; 00949 00950 } else { 00951 Assert(buf != (char*)0, "lost buf"); 00952 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */ 00953 } 00954 00955 #ifdef FORCE_STORED 00956 if (buf != (char*)0) { /* force stored block */ 00957 #else 00958 if (stored_len+4 <= opt_lenb && buf != (char*)0) { 00959 /* 4: two words for the lengths */ 00960 #endif 00961 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. 00962 * Otherwise we can't have processed more than WSIZE input bytes since 00963 * the last block flush, because compression would have been 00964 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to 00965 * transform a block into a stored block. 00966 */ 00967 _tr_stored_block(s, buf, stored_len, last); 00968 00969 #ifdef FORCE_STATIC 00970 } else if (static_lenb >= 0) { /* force static trees */ 00971 #else 00972 } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) { 00973 #endif 00974 send_bits(s, (STATIC_TREES<<1)+last, 3); 00975 compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree); 00976 #ifdef DEBUG 00977 s->compressed_len += 3 + s->static_len; 00978 #endif 00979 } else { 00980 send_bits(s, (DYN_TREES<<1)+last, 3); 00981 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1, 00982 max_blindex+1); 00983 compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree); 00984 #ifdef DEBUG 00985 s->compressed_len += 3 + s->opt_len; 00986 #endif 00987 } 00988 Assert (s->compressed_len == s->bits_sent, "bad compressed size"); 00989 /* The above check is made mod 2^32, for files larger than 512 MB 00990 * and uLong implemented on 32 bits. 00991 */ 00992 init_block(s); 00993 00994 if (last) { 00995 bi_windup(s); 00996 #ifdef DEBUG 00997 s->compressed_len += 7; /* align on byte boundary */ 00998 #endif 00999 } 01000 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3, 01001 s->compressed_len-7*last)); 01002 } 01003 01004 /* =========================================================================== 01005 * Save the match info and tally the frequency counts. Return true if 01006 * the current block must be flushed. 01007 */ 01008 int ZLIB_INTERNAL _tr_tally (s, dist, lc) 01009 deflate_state *s; 01010 unsigned dist; /* distance of matched string */ 01011 unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ 01012 { 01013 s->d_buf[s->last_lit] = (ush)dist; 01014 s->l_buf[s->last_lit++] = (uch)lc; 01015 if (dist == 0) { 01016 /* lc is the unmatched char */ 01017 s->dyn_ltree[lc].Freq++; 01018 } else { 01019 s->matches++; 01020 /* Here, lc is the match length - MIN_MATCH */ 01021 dist--; /* dist = match distance - 1 */ 01022 Assert((ush)dist < (ush)MAX_DIST(s) && 01023 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && 01024 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match"); 01025 01026 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++; 01027 s->dyn_dtree[d_code(dist)].Freq++; 01028 } 01029 01030 #ifdef TRUNCATE_BLOCK 01031 /* Try to guess if it is profitable to stop the current block here */ 01032 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) { 01033 /* Compute an upper bound for the compressed length */ 01034 ulg out_length = (ulg)s->last_lit*8L; 01035 ulg in_length = (ulg)((long)s->strstart - s->block_start); 01036 int dcode; 01037 for (dcode = 0; dcode < D_CODES; dcode++) { 01038 out_length += (ulg)s->dyn_dtree[dcode].Freq * 01039 (5L+extra_dbits[dcode]); 01040 } 01041 out_length >>= 3; 01042 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ", 01043 s->last_lit, in_length, out_length, 01044 100L - out_length*100L/in_length)); 01045 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1; 01046 } 01047 #endif 01048 return (s->last_lit == s->lit_bufsize-1); 01049 /* We avoid equality with lit_bufsize because of wraparound at 64K 01050 * on 16 bit machines and because stored blocks are restricted to 01051 * 64K-1 bytes. 01052 */ 01053 } 01054 01055 /* =========================================================================== 01056 * Send the block data compressed using the given Huffman trees 01057 */ 01058 local void compress_block(s, ltree, dtree) 01059 deflate_state *s; 01060 ct_data *ltree; /* literal tree */ 01061 ct_data *dtree; /* distance tree */ 01062 { 01063 unsigned dist; /* distance of matched string */ 01064 int lc; /* match length or unmatched char (if dist == 0) */ 01065 unsigned lx = 0; /* running index in l_buf */ 01066 unsigned code; /* the code to send */ 01067 int extra; /* number of extra bits to send */ 01068 01069 if (s->last_lit != 0) do { 01070 dist = s->d_buf[lx]; 01071 lc = s->l_buf[lx++]; 01072 if (dist == 0) { 01073 send_code(s, lc, ltree); /* send a literal byte */ 01074 Tracecv(isgraph(lc), (stderr," '%c' ", lc)); 01075 } else { 01076 /* Here, lc is the match length - MIN_MATCH */ 01077 code = _length_code[lc]; 01078 send_code(s, code+LITERALS+1, ltree); /* send the length code */ 01079 extra = extra_lbits[code]; 01080 if (extra != 0) { 01081 lc -= base_length[code]; 01082 send_bits(s, lc, extra); /* send the extra length bits */ 01083 } 01084 dist--; /* dist is now the match distance - 1 */ 01085 code = d_code(dist); 01086 Assert (code < D_CODES, "bad d_code"); 01087 01088 send_code(s, code, dtree); /* send the distance code */ 01089 extra = extra_dbits[code]; 01090 if (extra != 0) { 01091 dist -= base_dist[code]; 01092 send_bits(s, dist, extra); /* send the extra distance bits */ 01093 } 01094 } /* literal or match pair ? */ 01095 01096 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */ 01097 Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx, 01098 "pendingBuf overflow"); 01099 01100 } while (lx < s->last_lit); 01101 01102 send_code(s, END_BLOCK, ltree); 01103 } 01104 01105 /* =========================================================================== 01106 * Check if the data type is TEXT or BINARY, using the following algorithm: 01107 * - TEXT if the two conditions below are satisfied: 01108 * a) There are no non-portable control characters belonging to the 01109 * "black list" (0..6, 14..25, 28..31). 01110 * b) There is at least one printable character belonging to the 01111 * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255). 01112 * - BINARY otherwise. 01113 * - The following partially-portable control characters form a 01114 * "gray list" that is ignored in this detection algorithm: 01115 * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}). 01116 * IN assertion: the fields Freq of dyn_ltree are set. 01117 */ 01118 local int detect_data_type(s) 01119 deflate_state *s; 01120 { 01121 /* black_mask is the bit mask of black-listed bytes 01122 * set bits 0..6, 14..25, and 28..31 01123 * 0xf3ffc07f = binary 11110011111111111100000001111111 01124 */ 01125 unsigned long black_mask = 0xf3ffc07fUL; 01126 int n; 01127 01128 /* Check for non-textual ("black-listed") bytes. */ 01129 for (n = 0; n <= 31; n++, black_mask >>= 1) 01130 if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0)) 01131 return Z_BINARY; 01132 01133 /* Check for textual ("white-listed") bytes. */ 01134 if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0 01135 || s->dyn_ltree[13].Freq != 0) 01136 return Z_TEXT; 01137 for (n = 32; n < LITERALS; n++) 01138 if (s->dyn_ltree[n].Freq != 0) 01139 return Z_TEXT; 01140 01141 /* There are no "black-listed" or "white-listed" bytes: 01142 * this stream either is empty or has tolerated ("gray-listed") bytes only. 01143 */ 01144 return Z_BINARY; 01145 } 01146 01147 /* =========================================================================== 01148 * Reverse the first len bits of a code, using straightforward code (a faster 01149 * method would use a table) 01150 * IN assertion: 1 <= len <= 15 01151 */ 01152 local unsigned bi_reverse(code, len) 01153 unsigned code; /* the value to invert */ 01154 int len; /* its bit length */ 01155 { 01156 register unsigned res = 0; 01157 do { 01158 res |= code & 1; 01159 code >>= 1, res <<= 1; 01160 } while (--len > 0); 01161 return res >> 1; 01162 } 01163 01164 /* =========================================================================== 01165 * Flush the bit buffer, keeping at most 7 bits in it. 01166 */ 01167 local void bi_flush(s) 01168 deflate_state *s; 01169 { 01170 if (s->bi_valid == 16) { 01171 put_short(s, s->bi_buf); 01172 s->bi_buf = 0; 01173 s->bi_valid = 0; 01174 } else if (s->bi_valid >= 8) { 01175 put_byte(s, (Byte)s->bi_buf); 01176 s->bi_buf >>= 8; 01177 s->bi_valid -= 8; 01178 } 01179 } 01180 01181 /* =========================================================================== 01182 * Flush the bit buffer and align the output on a byte boundary 01183 */ 01184 local void bi_windup(s) 01185 deflate_state *s; 01186 { 01187 if (s->bi_valid > 8) { 01188 put_short(s, s->bi_buf); 01189 } else if (s->bi_valid > 0) { 01190 put_byte(s, (Byte)s->bi_buf); 01191 } 01192 s->bi_buf = 0; 01193 s->bi_valid = 0; 01194 #ifdef DEBUG 01195 s->bits_sent = (s->bits_sent+7) & ~7; 01196 #endif 01197 } 01198 01199 /* =========================================================================== 01200 * Copy a stored block, storing first the length and its 01201 * one's complement if requested. 01202 */ 01203 local void copy_block(s, buf, len, header) 01204 deflate_state *s; 01205 charf *buf; /* the input data */ 01206 unsigned len; /* its length */ 01207 int header; /* true if block header must be written */ 01208 { 01209 bi_windup(s); /* align on byte boundary */ 01210 01211 if (header) { 01212 put_short(s, (ush)len); 01213 put_short(s, (ush)~len); 01214 #ifdef DEBUG 01215 s->bits_sent += 2*16; 01216 #endif 01217 } 01218 #ifdef DEBUG 01219 s->bits_sent += (ulg)len<<3; 01220 #endif 01221 while (len--) { 01222 put_byte(s, *buf++); 01223 } 01224 }
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