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Revision 31 - (show annotations) (download)
Tue Sep 7 03:24:11 2010 UTC (10 years, 1 month ago) by william
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committing r3113 initial commit again...
1 /* trees.c -- output deflated data using Huffman coding
2 * Copyright (C) 1995-2009 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 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 #define Buf_size (8 * 2*sizeof(char))
78 /* Number of bits used within bi_buf. (bi_buf might be implemented on
79 * more than 16 bits on some systems.)
80 */
81
82 /* ===========================================================================
83 * Local data. These are initialized only once.
84 */
85
86 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
87
88 #if defined(GEN_TREES_H) || !defined(STDC)
89 /* non ANSI compilers may not accept trees.h */
90
91 local ct_data static_ltree[L_CODES+2];
92 /* The static literal tree. Since the bit lengths are imposed, there is no
93 * need for the L_CODES extra codes used during heap construction. However
94 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
95 * below).
96 */
97
98 local ct_data static_dtree[D_CODES];
99 /* The static distance tree. (Actually a trivial tree since all codes use
100 * 5 bits.)
101 */
102
103 uch _dist_code[DIST_CODE_LEN];
104 /* Distance codes. The first 256 values correspond to the distances
105 * 3 .. 258, the last 256 values correspond to the top 8 bits of
106 * the 15 bit distances.
107 */
108
109 uch _length_code[MAX_MATCH-MIN_MATCH+1];
110 /* length code for each normalized match length (0 == MIN_MATCH) */
111
112 local int base_length[LENGTH_CODES];
113 /* First normalized length for each code (0 = MIN_MATCH) */
114
115 local int base_dist[D_CODES];
116 /* First normalized distance for each code (0 = distance of 1) */
117
118 #else
119 # include "trees.h"
120 #endif /* GEN_TREES_H */
121
122 struct static_tree_desc_s {
123 const ct_data *static_tree; /* static tree or NULL */
124 const intf *extra_bits; /* extra bits for each code or NULL */
125 int extra_base; /* base index for extra_bits */
126 int elems; /* max number of elements in the tree */
127 int max_length; /* max bit length for the codes */
128 };
129
130 local static_tree_desc static_l_desc =
131 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
132
133 local static_tree_desc static_d_desc =
134 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
135
136 local static_tree_desc static_bl_desc =
137 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
138
139 /* ===========================================================================
140 * Local (static) routines in this file.
141 */
142
143 local void tr_static_init OF((void));
144 local void init_block OF((deflate_state *s));
145 local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
146 local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
147 local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
148 local void build_tree OF((deflate_state *s, tree_desc *desc));
149 local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
150 local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
151 local int build_bl_tree OF((deflate_state *s));
152 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
153 int blcodes));
154 local void compress_block OF((deflate_state *s, ct_data *ltree,
155 ct_data *dtree));
156 local int detect_data_type OF((deflate_state *s));
157 local unsigned bi_reverse OF((unsigned value, int length));
158 local void bi_windup OF((deflate_state *s));
159 local void bi_flush OF((deflate_state *s));
160 local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
161 int header));
162
163 #ifdef GEN_TREES_H
164 local void gen_trees_header OF((void));
165 #endif
166
167 #ifndef DEBUG
168 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
169 /* Send a code of the given tree. c and tree must not have side effects */
170
171 #else /* DEBUG */
172 # define send_code(s, c, tree) \
173 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
174 send_bits(s, tree[c].Code, tree[c].Len); }
175 #endif
176
177 /* ===========================================================================
178 * Output a short LSB first on the stream.
179 * IN assertion: there is enough room in pendingBuf.
180 */
181 #define put_short(s, w) { \
182 put_byte(s, (uch)((w) & 0xff)); \
183 put_byte(s, (uch)((ush)(w) >> 8)); \
184 }
185
186 /* ===========================================================================
187 * Send a value on a given number of bits.
188 * IN assertion: length <= 16 and value fits in length bits.
189 */
190 #ifdef DEBUG
191 local void send_bits OF((deflate_state *s, int value, int length));
192
193 local void send_bits(s, value, length)
194 deflate_state *s;
195 int value; /* value to send */
196 int length; /* number of bits */
197 {
198 Tracevv((stderr," l %2d v %4x ", length, value));
199 Assert(length > 0 && length <= 15, "invalid length");
200 s->bits_sent += (ulg)length;
201
202 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
203 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
204 * unused bits in value.
205 */
206 if (s->bi_valid > (int)Buf_size - length) {
207 s->bi_buf |= (ush)value << s->bi_valid;
208 put_short(s, s->bi_buf);
209 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
210 s->bi_valid += length - Buf_size;
211 } else {
212 s->bi_buf |= (ush)value << s->bi_valid;
213 s->bi_valid += length;
214 }
215 }
216 #else /* !DEBUG */
217
218 #define send_bits(s, value, length) \
219 { int len = length;\
220 if (s->bi_valid > (int)Buf_size - len) {\
221 int val = value;\
222 s->bi_buf |= (ush)val << s->bi_valid;\
223 put_short(s, s->bi_buf);\
224 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
225 s->bi_valid += len - Buf_size;\
226 } else {\
227 s->bi_buf |= (ush)(value) << s->bi_valid;\
228 s->bi_valid += len;\
229 }\
230 }
231 #endif /* DEBUG */
232
233
234 /* the arguments must not have side effects */
235
236 /* ===========================================================================
237 * Initialize the various 'constant' tables.
238 */
239 local void tr_static_init()
240 {
241 #if defined(GEN_TREES_H) || !defined(STDC)
242 static int static_init_done = 0;
243 int n; /* iterates over tree elements */
244 int bits; /* bit counter */
245 int length; /* length value */
246 int code; /* code value */
247 int dist; /* distance index */
248 ush bl_count[MAX_BITS+1];
249 /* number of codes at each bit length for an optimal tree */
250
251 if (static_init_done) return;
252
253 /* For some embedded targets, global variables are not initialized: */
254 #ifdef NO_INIT_GLOBAL_POINTERS
255 static_l_desc.static_tree = static_ltree;
256 static_l_desc.extra_bits = extra_lbits;
257 static_d_desc.static_tree = static_dtree;
258 static_d_desc.extra_bits = extra_dbits;
259 static_bl_desc.extra_bits = extra_blbits;
260 #endif
261
262 /* Initialize the mapping length (0..255) -> length code (0..28) */
263 length = 0;
264 for (code = 0; code < LENGTH_CODES-1; code++) {
265 base_length[code] = length;
266 for (n = 0; n < (1<<extra_lbits[code]); n++) {
267 _length_code[length++] = (uch)code;
268 }
269 }
270 Assert (length == 256, "tr_static_init: length != 256");
271 /* Note that the length 255 (match length 258) can be represented
272 * in two different ways: code 284 + 5 bits or code 285, so we
273 * overwrite length_code[255] to use the best encoding:
274 */
275 _length_code[length-1] = (uch)code;
276
277 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
278 dist = 0;
279 for (code = 0 ; code < 16; code++) {
280 base_dist[code] = dist;
281 for (n = 0; n < (1<<extra_dbits[code]); n++) {
282 _dist_code[dist++] = (uch)code;
283 }
284 }
285 Assert (dist == 256, "tr_static_init: dist != 256");
286 dist >>= 7; /* from now on, all distances are divided by 128 */
287 for ( ; code < D_CODES; code++) {
288 base_dist[code] = dist << 7;
289 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
290 _dist_code[256 + dist++] = (uch)code;
291 }
292 }
293 Assert (dist == 256, "tr_static_init: 256+dist != 512");
294
295 /* Construct the codes of the static literal tree */
296 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
297 n = 0;
298 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
299 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
300 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
301 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
302 /* Codes 286 and 287 do not exist, but we must include them in the
303 * tree construction to get a canonical Huffman tree (longest code
304 * all ones)
305 */
306 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
307
308 /* The static distance tree is trivial: */
309 for (n = 0; n < D_CODES; n++) {
310 static_dtree[n].Len = 5;
311 static_dtree[n].Code = bi_reverse((unsigned)n, 5);
312 }
313 static_init_done = 1;
314
315 # ifdef GEN_TREES_H
316 gen_trees_header();
317 # endif
318 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
319 }
320
321 /* ===========================================================================
322 * Genererate the file trees.h describing the static trees.
323 */
324 #ifdef GEN_TREES_H
325 # ifndef DEBUG
326 # include <stdio.h>
327 # endif
328
329 # define SEPARATOR(i, last, width) \
330 ((i) == (last)? "\n};\n\n" : \
331 ((i) % (width) == (width)-1 ? ",\n" : ", "))
332
333 void gen_trees_header()
334 {
335 FILE *header = fopen("trees.h", "w");
336 int i;
337
338 Assert (header != NULL, "Can't open trees.h");
339 fprintf(header,
340 "/* header created automatically with -DGEN_TREES_H */\n\n");
341
342 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
343 for (i = 0; i < L_CODES+2; i++) {
344 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
345 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
346 }
347
348 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
349 for (i = 0; i < D_CODES; i++) {
350 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
351 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
352 }
353
354 fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n");
355 for (i = 0; i < DIST_CODE_LEN; i++) {
356 fprintf(header, "%2u%s", _dist_code[i],
357 SEPARATOR(i, DIST_CODE_LEN-1, 20));
358 }
359
360 fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
361 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
362 fprintf(header, "%2u%s", _length_code[i],
363 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
364 }
365
366 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
367 for (i = 0; i < LENGTH_CODES; i++) {
368 fprintf(header, "%1u%s", base_length[i],
369 SEPARATOR(i, LENGTH_CODES-1, 20));
370 }
371
372 fprintf(header, "local const int base_dist[D_CODES] = {\n");
373 for (i = 0; i < D_CODES; i++) {
374 fprintf(header, "%5u%s", base_dist[i],
375 SEPARATOR(i, D_CODES-1, 10));
376 }
377
378 fclose(header);
379 }
380 #endif /* GEN_TREES_H */
381
382 /* ===========================================================================
383 * Initialize the tree data structures for a new zlib stream.
384 */
385 void _tr_init(s)
386 deflate_state *s;
387 {
388 tr_static_init();
389
390 s->l_desc.dyn_tree = s->dyn_ltree;
391 s->l_desc.stat_desc = &static_l_desc;
392
393 s->d_desc.dyn_tree = s->dyn_dtree;
394 s->d_desc.stat_desc = &static_d_desc;
395
396 s->bl_desc.dyn_tree = s->bl_tree;
397 s->bl_desc.stat_desc = &static_bl_desc;
398
399 s->bi_buf = 0;
400 s->bi_valid = 0;
401 s->last_eob_len = 8; /* enough lookahead for inflate */
402 #ifdef DEBUG
403 s->compressed_len = 0L;
404 s->bits_sent = 0L;
405 #endif
406
407 /* Initialize the first block of the first file: */
408 init_block(s);
409 }
410
411 /* ===========================================================================
412 * Initialize a new block.
413 */
414 local void init_block(s)
415 deflate_state *s;
416 {
417 int n; /* iterates over tree elements */
418
419 /* Initialize the trees. */
420 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
421 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
422 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
423
424 s->dyn_ltree[END_BLOCK].Freq = 1;
425 s->opt_len = s->static_len = 0L;
426 s->last_lit = s->matches = 0;
427 }
428
429 #define SMALLEST 1
430 /* Index within the heap array of least frequent node in the Huffman tree */
431
432
433 /* ===========================================================================
434 * Remove the smallest element from the heap and recreate the heap with
435 * one less element. Updates heap and heap_len.
436 */
437 #define pqremove(s, tree, top) \
438 {\
439 top = s->heap[SMALLEST]; \
440 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
441 pqdownheap(s, tree, SMALLEST); \
442 }
443
444 /* ===========================================================================
445 * Compares to subtrees, using the tree depth as tie breaker when
446 * the subtrees have equal frequency. This minimizes the worst case length.
447 */
448 #define smaller(tree, n, m, depth) \
449 (tree[n].Freq < tree[m].Freq || \
450 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
451
452 /* ===========================================================================
453 * Restore the heap property by moving down the tree starting at node k,
454 * exchanging a node with the smallest of its two sons if necessary, stopping
455 * when the heap property is re-established (each father smaller than its
456 * two sons).
457 */
458 local void pqdownheap(s, tree, k)
459 deflate_state *s;
460 ct_data *tree; /* the tree to restore */
461 int k; /* node to move down */
462 {
463 int v = s->heap[k];
464 int j = k << 1; /* left son of k */
465 while (j <= s->heap_len) {
466 /* Set j to the smallest of the two sons: */
467 if (j < s->heap_len &&
468 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
469 j++;
470 }
471 /* Exit if v is smaller than both sons */
472 if (smaller(tree, v, s->heap[j], s->depth)) break;
473
474 /* Exchange v with the smallest son */
475 s->heap[k] = s->heap[j]; k = j;
476
477 /* And continue down the tree, setting j to the left son of k */
478 j <<= 1;
479 }
480 s->heap[k] = v;
481 }
482
483 /* ===========================================================================
484 * Compute the optimal bit lengths for a tree and update the total bit length
485 * for the current block.
486 * IN assertion: the fields freq and dad are set, heap[heap_max] and
487 * above are the tree nodes sorted by increasing frequency.
488 * OUT assertions: the field len is set to the optimal bit length, the
489 * array bl_count contains the frequencies for each bit length.
490 * The length opt_len is updated; static_len is also updated if stree is
491 * not null.
492 */
493 local void gen_bitlen(s, desc)
494 deflate_state *s;
495 tree_desc *desc; /* the tree descriptor */
496 {
497 ct_data *tree = desc->dyn_tree;
498 int max_code = desc->max_code;
499 const ct_data *stree = desc->stat_desc->static_tree;
500 const intf *extra = desc->stat_desc->extra_bits;
501 int base = desc->stat_desc->extra_base;
502 int max_length = desc->stat_desc->max_length;
503 int h; /* heap index */
504 int n, m; /* iterate over the tree elements */
505 int bits; /* bit length */
506 int xbits; /* extra bits */
507 ush f; /* frequency */
508 int overflow = 0; /* number of elements with bit length too large */
509
510 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
511
512 /* In a first pass, compute the optimal bit lengths (which may
513 * overflow in the case of the bit length tree).
514 */
515 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
516
517 for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
518 n = s->heap[h];
519 bits = tree[tree[n].Dad].Len + 1;
520 if (bits > max_length) bits = max_length, overflow++;
521 tree[n].Len = (ush)bits;
522 /* We overwrite tree[n].Dad which is no longer needed */
523
524 if (n > max_code) continue; /* not a leaf node */
525
526 s->bl_count[bits]++;
527 xbits = 0;
528 if (n >= base) xbits = extra[n-base];
529 f = tree[n].Freq;
530 s->opt_len += (ulg)f * (bits + xbits);
531 if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
532 }
533 if (overflow == 0) return;
534
535 Trace((stderr,"\nbit length overflow\n"));
536 /* This happens for example on obj2 and pic of the Calgary corpus */
537
538 /* Find the first bit length which could increase: */
539 do {
540 bits = max_length-1;
541 while (s->bl_count[bits] == 0) bits--;
542 s->bl_count[bits]--; /* move one leaf down the tree */
543 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
544 s->bl_count[max_length]--;
545 /* The brother of the overflow item also moves one step up,
546 * but this does not affect bl_count[max_length]
547 */
548 overflow -= 2;
549 } while (overflow > 0);
550
551 /* Now recompute all bit lengths, scanning in increasing frequency.
552 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
553 * lengths instead of fixing only the wrong ones. This idea is taken
554 * from 'ar' written by Haruhiko Okumura.)
555 */
556 for (bits = max_length; bits != 0; bits--) {
557 n = s->bl_count[bits];
558 while (n != 0) {
559 m = s->heap[--h];
560 if (m > max_code) continue;
561 if ((unsigned) tree[m].Len != (unsigned) bits) {
562 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
563 s->opt_len += ((long)bits - (long)tree[m].Len)
564 *(long)tree[m].Freq;
565 tree[m].Len = (ush)bits;
566 }
567 n--;
568 }
569 }
570 }
571
572 /* ===========================================================================
573 * Generate the codes for a given tree and bit counts (which need not be
574 * optimal).
575 * IN assertion: the array bl_count contains the bit length statistics for
576 * the given tree and the field len is set for all tree elements.
577 * OUT assertion: the field code is set for all tree elements of non
578 * zero code length.
579 */
580 local void gen_codes (tree, max_code, bl_count)
581 ct_data *tree; /* the tree to decorate */
582 int max_code; /* largest code with non zero frequency */
583 ushf *bl_count; /* number of codes at each bit length */
584 {
585 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
586 ush code = 0; /* running code value */
587 int bits; /* bit index */
588 int n; /* code index */
589
590 /* The distribution counts are first used to generate the code values
591 * without bit reversal.
592 */
593 for (bits = 1; bits <= MAX_BITS; bits++) {
594 next_code[bits] = code = (code + bl_count[bits-1]) << 1;
595 }
596 /* Check that the bit counts in bl_count are consistent. The last code
597 * must be all ones.
598 */
599 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
600 "inconsistent bit counts");
601 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
602
603 for (n = 0; n <= max_code; n++) {
604 int len = tree[n].Len;
605 if (len == 0) continue;
606 /* Now reverse the bits */
607 tree[n].Code = bi_reverse(next_code[len]++, len);
608
609 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
610 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
611 }
612 }
613
614 /* ===========================================================================
615 * Construct one Huffman tree and assigns the code bit strings and lengths.
616 * Update the total bit length for the current block.
617 * IN assertion: the field freq is set for all tree elements.
618 * OUT assertions: the fields len and code are set to the optimal bit length
619 * and corresponding code. The length opt_len is updated; static_len is
620 * also updated if stree is not null. The field max_code is set.
621 */
622 local void build_tree(s, desc)
623 deflate_state *s;
624 tree_desc *desc; /* the tree descriptor */
625 {
626 ct_data *tree = desc->dyn_tree;
627 const ct_data *stree = desc->stat_desc->static_tree;
628 int elems = desc->stat_desc->elems;
629 int n, m; /* iterate over heap elements */
630 int max_code = -1; /* largest code with non zero frequency */
631 int node; /* new node being created */
632
633 /* Construct the initial heap, with least frequent element in
634 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
635 * heap[0] is not used.
636 */
637 s->heap_len = 0, s->heap_max = HEAP_SIZE;
638
639 for (n = 0; n < elems; n++) {
640 if (tree[n].Freq != 0) {
641 s->heap[++(s->heap_len)] = max_code = n;
642 s->depth[n] = 0;
643 } else {
644 tree[n].Len = 0;
645 }
646 }
647
648 /* The pkzip format requires that at least one distance code exists,
649 * and that at least one bit should be sent even if there is only one
650 * possible code. So to avoid special checks later on we force at least
651 * two codes of non zero frequency.
652 */
653 while (s->heap_len < 2) {
654 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
655 tree[node].Freq = 1;
656 s->depth[node] = 0;
657 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
658 /* node is 0 or 1 so it does not have extra bits */
659 }
660 desc->max_code = max_code;
661
662 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
663 * establish sub-heaps of increasing lengths:
664 */
665 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
666
667 /* Construct the Huffman tree by repeatedly combining the least two
668 * frequent nodes.
669 */
670 node = elems; /* next internal node of the tree */
671 do {
672 pqremove(s, tree, n); /* n = node of least frequency */
673 m = s->heap[SMALLEST]; /* m = node of next least frequency */
674
675 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
676 s->heap[--(s->heap_max)] = m;
677
678 /* Create a new node father of n and m */
679 tree[node].Freq = tree[n].Freq + tree[m].Freq;
680 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
681 s->depth[n] : s->depth[m]) + 1);
682 tree[n].Dad = tree[m].Dad = (ush)node;
683 #ifdef DUMP_BL_TREE
684 if (tree == s->bl_tree) {
685 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
686 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
687 }
688 #endif
689 /* and insert the new node in the heap */
690 s->heap[SMALLEST] = node++;
691 pqdownheap(s, tree, SMALLEST);
692
693 } while (s->heap_len >= 2);
694
695 s->heap[--(s->heap_max)] = s->heap[SMALLEST];
696
697 /* At this point, the fields freq and dad are set. We can now
698 * generate the bit lengths.
699 */
700 gen_bitlen(s, (tree_desc *)desc);
701
702 /* The field len is now set, we can generate the bit codes */
703 gen_codes ((ct_data *)tree, max_code, s->bl_count);
704 }
705
706 /* ===========================================================================
707 * Scan a literal or distance tree to determine the frequencies of the codes
708 * in the bit length tree.
709 */
710 local void scan_tree (s, tree, max_code)
711 deflate_state *s;
712 ct_data *tree; /* the tree to be scanned */
713 int max_code; /* and its largest code of non zero frequency */
714 {
715 int n; /* iterates over all tree elements */
716 int prevlen = -1; /* last emitted length */
717 int curlen; /* length of current code */
718 int nextlen = tree[0].Len; /* length of next code */
719 int count = 0; /* repeat count of the current code */
720 int max_count = 7; /* max repeat count */
721 int min_count = 4; /* min repeat count */
722
723 if (nextlen == 0) max_count = 138, min_count = 3;
724 tree[max_code+1].Len = (ush)0xffff; /* guard */
725
726 for (n = 0; n <= max_code; n++) {
727 curlen = nextlen; nextlen = tree[n+1].Len;
728 if (++count < max_count && curlen == nextlen) {
729 continue;
730 } else if (count < min_count) {
731 s->bl_tree[curlen].Freq += count;
732 } else if (curlen != 0) {
733 if (curlen != prevlen) s->bl_tree[curlen].Freq++;
734 s->bl_tree[REP_3_6].Freq++;
735 } else if (count <= 10) {
736 s->bl_tree[REPZ_3_10].Freq++;
737 } else {
738 s->bl_tree[REPZ_11_138].Freq++;
739 }
740 count = 0; prevlen = curlen;
741 if (nextlen == 0) {
742 max_count = 138, min_count = 3;
743 } else if (curlen == nextlen) {
744 max_count = 6, min_count = 3;
745 } else {
746 max_count = 7, min_count = 4;
747 }
748 }
749 }
750
751 /* ===========================================================================
752 * Send a literal or distance tree in compressed form, using the codes in
753 * bl_tree.
754 */
755 local void send_tree (s, tree, max_code)
756 deflate_state *s;
757 ct_data *tree; /* the tree to be scanned */
758 int max_code; /* and its largest code of non zero frequency */
759 {
760 int n; /* iterates over all tree elements */
761 int prevlen = -1; /* last emitted length */
762 int curlen; /* length of current code */
763 int nextlen = tree[0].Len; /* length of next code */
764 int count = 0; /* repeat count of the current code */
765 int max_count = 7; /* max repeat count */
766 int min_count = 4; /* min repeat count */
767
768 /* tree[max_code+1].Len = -1; */ /* guard already set */
769 if (nextlen == 0) max_count = 138, min_count = 3;
770
771 for (n = 0; n <= max_code; n++) {
772 curlen = nextlen; nextlen = tree[n+1].Len;
773 if (++count < max_count && curlen == nextlen) {
774 continue;
775 } else if (count < min_count) {
776 do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
777
778 } else if (curlen != 0) {
779 if (curlen != prevlen) {
780 send_code(s, curlen, s->bl_tree); count--;
781 }
782 Assert(count >= 3 && count <= 6, " 3_6?");
783 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
784
785 } else if (count <= 10) {
786 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
787
788 } else {
789 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
790 }
791 count = 0; prevlen = curlen;
792 if (nextlen == 0) {
793 max_count = 138, min_count = 3;
794 } else if (curlen == nextlen) {
795 max_count = 6, min_count = 3;
796 } else {
797 max_count = 7, min_count = 4;
798 }
799 }
800 }
801
802 /* ===========================================================================
803 * Construct the Huffman tree for the bit lengths and return the index in
804 * bl_order of the last bit length code to send.
805 */
806 local int build_bl_tree(s)
807 deflate_state *s;
808 {
809 int max_blindex; /* index of last bit length code of non zero freq */
810
811 /* Determine the bit length frequencies for literal and distance trees */
812 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
813 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
814
815 /* Build the bit length tree: */
816 build_tree(s, (tree_desc *)(&(s->bl_desc)));
817 /* opt_len now includes the length of the tree representations, except
818 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
819 */
820
821 /* Determine the number of bit length codes to send. The pkzip format
822 * requires that at least 4 bit length codes be sent. (appnote.txt says
823 * 3 but the actual value used is 4.)
824 */
825 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
826 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
827 }
828 /* Update opt_len to include the bit length tree and counts */
829 s->opt_len += 3*(max_blindex+1) + 5+5+4;
830 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
831 s->opt_len, s->static_len));
832
833 return max_blindex;
834 }
835
836 /* ===========================================================================
837 * Send the header for a block using dynamic Huffman trees: the counts, the
838 * lengths of the bit length codes, the literal tree and the distance tree.
839 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
840 */
841 local void send_all_trees(s, lcodes, dcodes, blcodes)
842 deflate_state *s;
843 int lcodes, dcodes, blcodes; /* number of codes for each tree */
844 {
845 int rank; /* index in bl_order */
846
847 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
848 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
849 "too many codes");
850 Tracev((stderr, "\nbl counts: "));
851 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
852 send_bits(s, dcodes-1, 5);
853 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
854 for (rank = 0; rank < blcodes; rank++) {
855 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
856 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
857 }
858 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
859
860 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
861 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
862
863 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
864 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
865 }
866
867 /* ===========================================================================
868 * Send a stored block
869 */
870 void _tr_stored_block(s, buf, stored_len, last)
871 deflate_state *s;
872 charf *buf; /* input block */
873 ulg stored_len; /* length of input block */
874 int last; /* one if this is the last block for a file */
875 {
876 send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */
877 #ifdef DEBUG
878 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
879 s->compressed_len += (stored_len + 4) << 3;
880 #endif
881 copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
882 }
883
884 /* ===========================================================================
885 * Send one empty static block to give enough lookahead for inflate.
886 * This takes 10 bits, of which 7 may remain in the bit buffer.
887 * The current inflate code requires 9 bits of lookahead. If the
888 * last two codes for the previous block (real code plus EOB) were coded
889 * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
890 * the last real code. In this case we send two empty static blocks instead
891 * of one. (There are no problems if the previous block is stored or fixed.)
892 * To simplify the code, we assume the worst case of last real code encoded
893 * on one bit only.
894 */
895 void _tr_align(s)
896 deflate_state *s;
897 {
898 send_bits(s, STATIC_TREES<<1, 3);
899 send_code(s, END_BLOCK, static_ltree);
900 #ifdef DEBUG
901 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
902 #endif
903 bi_flush(s);
904 /* Of the 10 bits for the empty block, we have already sent
905 * (10 - bi_valid) bits. The lookahead for the last real code (before
906 * the EOB of the previous block) was thus at least one plus the length
907 * of the EOB plus what we have just sent of the empty static block.
908 */
909 if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
910 send_bits(s, STATIC_TREES<<1, 3);
911 send_code(s, END_BLOCK, static_ltree);
912 #ifdef DEBUG
913 s->compressed_len += 10L;
914 #endif
915 bi_flush(s);
916 }
917 s->last_eob_len = 7;
918 }
919
920 /* ===========================================================================
921 * Determine the best encoding for the current block: dynamic trees, static
922 * trees or store, and output the encoded block to the zip file.
923 */
924 void _tr_flush_block(s, buf, stored_len, last)
925 deflate_state *s;
926 charf *buf; /* input block, or NULL if too old */
927 ulg stored_len; /* length of input block */
928 int last; /* one if this is the last block for a file */
929 {
930 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
931 int max_blindex = 0; /* index of last bit length code of non zero freq */
932
933 /* Build the Huffman trees unless a stored block is forced */
934 if (s->level > 0) {
935
936 /* Check if the file is binary or text */
937 if (s->strm->data_type == Z_UNKNOWN)
938 s->strm->data_type = detect_data_type(s);
939
940 /* Construct the literal and distance trees */
941 build_tree(s, (tree_desc *)(&(s->l_desc)));
942 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
943 s->static_len));
944
945 build_tree(s, (tree_desc *)(&(s->d_desc)));
946 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
947 s->static_len));
948 /* At this point, opt_len and static_len are the total bit lengths of
949 * the compressed block data, excluding the tree representations.
950 */
951
952 /* Build the bit length tree for the above two trees, and get the index
953 * in bl_order of the last bit length code to send.
954 */
955 max_blindex = build_bl_tree(s);
956
957 /* Determine the best encoding. Compute the block lengths in bytes. */
958 opt_lenb = (s->opt_len+3+7)>>3;
959 static_lenb = (s->static_len+3+7)>>3;
960
961 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
962 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
963 s->last_lit));
964
965 if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
966
967 } else {
968 Assert(buf != (char*)0, "lost buf");
969 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
970 }
971
972 #ifdef FORCE_STORED
973 if (buf != (char*)0) { /* force stored block */
974 #else
975 if (stored_len+4 <= opt_lenb && buf != (char*)0) {
976 /* 4: two words for the lengths */
977 #endif
978 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
979 * Otherwise we can't have processed more than WSIZE input bytes since
980 * the last block flush, because compression would have been
981 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
982 * transform a block into a stored block.
983 */
984 _tr_stored_block(s, buf, stored_len, last);
985
986 #ifdef FORCE_STATIC
987 } else if (static_lenb >= 0) { /* force static trees */
988 #else
989 } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
990 #endif
991 send_bits(s, (STATIC_TREES<<1)+last, 3);
992 compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
993 #ifdef DEBUG
994 s->compressed_len += 3 + s->static_len;
995 #endif
996 } else {
997 send_bits(s, (DYN_TREES<<1)+last, 3);
998 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
999 max_blindex+1);
1000 compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
1001 #ifdef DEBUG
1002 s->compressed_len += 3 + s->opt_len;
1003 #endif
1004 }
1005 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1006 /* The above check is made mod 2^32, for files larger than 512 MB
1007 * and uLong implemented on 32 bits.
1008 */
1009 init_block(s);
1010
1011 if (last) {
1012 bi_windup(s);
1013 #ifdef DEBUG
1014 s->compressed_len += 7; /* align on byte boundary */
1015 #endif
1016 }
1017 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1018 s->compressed_len-7*last));
1019 }
1020
1021 /* ===========================================================================
1022 * Save the match info and tally the frequency counts. Return true if
1023 * the current block must be flushed.
1024 */
1025 int _tr_tally (s, dist, lc)
1026 deflate_state *s;
1027 unsigned dist; /* distance of matched string */
1028 unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1029 {
1030 s->d_buf[s->last_lit] = (ush)dist;
1031 s->l_buf[s->last_lit++] = (uch)lc;
1032 if (dist == 0) {
1033 /* lc is the unmatched char */
1034 s->dyn_ltree[lc].Freq++;
1035 } else {
1036 s->matches++;
1037 /* Here, lc is the match length - MIN_MATCH */
1038 dist--; /* dist = match distance - 1 */
1039 Assert((ush)dist < (ush)MAX_DIST(s) &&
1040 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1041 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1042
1043 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1044 s->dyn_dtree[d_code(dist)].Freq++;
1045 }
1046
1047 #ifdef TRUNCATE_BLOCK
1048 /* Try to guess if it is profitable to stop the current block here */
1049 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1050 /* Compute an upper bound for the compressed length */
1051 ulg out_length = (ulg)s->last_lit*8L;
1052 ulg in_length = (ulg)((long)s->strstart - s->block_start);
1053 int dcode;
1054 for (dcode = 0; dcode < D_CODES; dcode++) {
1055 out_length += (ulg)s->dyn_dtree[dcode].Freq *
1056 (5L+extra_dbits[dcode]);
1057 }
1058 out_length >>= 3;
1059 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1060 s->last_lit, in_length, out_length,
1061 100L - out_length*100L/in_length));
1062 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1063 }
1064 #endif
1065 return (s->last_lit == s->lit_bufsize-1);
1066 /* We avoid equality with lit_bufsize because of wraparound at 64K
1067 * on 16 bit machines and because stored blocks are restricted to
1068 * 64K-1 bytes.
1069 */
1070 }
1071
1072 /* ===========================================================================
1073 * Send the block data compressed using the given Huffman trees
1074 */
1075 local void compress_block(s, ltree, dtree)
1076 deflate_state *s;
1077 ct_data *ltree; /* literal tree */
1078 ct_data *dtree; /* distance tree */
1079 {
1080 unsigned dist; /* distance of matched string */
1081 int lc; /* match length or unmatched char (if dist == 0) */
1082 unsigned lx = 0; /* running index in l_buf */
1083 unsigned code; /* the code to send */
1084 int extra; /* number of extra bits to send */
1085
1086 if (s->last_lit != 0) do {
1087 dist = s->d_buf[lx];
1088 lc = s->l_buf[lx++];
1089 if (dist == 0) {
1090 send_code(s, lc, ltree); /* send a literal byte */
1091 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1092 } else {
1093 /* Here, lc is the match length - MIN_MATCH */
1094 code = _length_code[lc];
1095 send_code(s, code+LITERALS+1, ltree); /* send the length code */
1096 extra = extra_lbits[code];
1097 if (extra != 0) {
1098 lc -= base_length[code];
1099 send_bits(s, lc, extra); /* send the extra length bits */
1100 }
1101 dist--; /* dist is now the match distance - 1 */
1102 code = d_code(dist);
1103 Assert (code < D_CODES, "bad d_code");
1104
1105 send_code(s, code, dtree); /* send the distance code */
1106 extra = extra_dbits[code];
1107 if (extra != 0) {
1108 dist -= base_dist[code];
1109 send_bits(s, dist, extra); /* send the extra distance bits */
1110 }
1111 } /* literal or match pair ? */
1112
1113 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1114 Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1115 "pendingBuf overflow");
1116
1117 } while (lx < s->last_lit);
1118
1119 send_code(s, END_BLOCK, ltree);
1120 s->last_eob_len = ltree[END_BLOCK].Len;
1121 }
1122
1123 /* ===========================================================================
1124 * Check if the data type is TEXT or BINARY, using the following algorithm:
1125 * - TEXT if the two conditions below are satisfied:
1126 * a) There are no non-portable control characters belonging to the
1127 * "black list" (0..6, 14..25, 28..31).
1128 * b) There is at least one printable character belonging to the
1129 * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1130 * - BINARY otherwise.
1131 * - The following partially-portable control characters form a
1132 * "gray list" that is ignored in this detection algorithm:
1133 * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1134 * IN assertion: the fields Freq of dyn_ltree are set.
1135 */
1136 local int detect_data_type(s)
1137 deflate_state *s;
1138 {
1139 /* black_mask is the bit mask of black-listed bytes
1140 * set bits 0..6, 14..25, and 28..31
1141 * 0xf3ffc07f = binary 11110011111111111100000001111111
1142 */
1143 unsigned long black_mask = 0xf3ffc07fUL;
1144 int n;
1145
1146 /* Check for non-textual ("black-listed") bytes. */
1147 for (n = 0; n <= 31; n++, black_mask >>= 1)
1148 if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1149 return Z_BINARY;
1150
1151 /* Check for textual ("white-listed") bytes. */
1152 if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1153 || s->dyn_ltree[13].Freq != 0)
1154 return Z_TEXT;
1155 for (n = 32; n < LITERALS; n++)
1156 if (s->dyn_ltree[n].Freq != 0)
1157 return Z_TEXT;
1158
1159 /* There are no "black-listed" or "white-listed" bytes:
1160 * this stream either is empty or has tolerated ("gray-listed") bytes only.
1161 */
1162 return Z_BINARY;
1163 }
1164
1165 /* ===========================================================================
1166 * Reverse the first len bits of a code, using straightforward code (a faster
1167 * method would use a table)
1168 * IN assertion: 1 <= len <= 15
1169 */
1170 local unsigned bi_reverse(code, len)
1171 unsigned code; /* the value to invert */
1172 int len; /* its bit length */
1173 {
1174 register unsigned res = 0;
1175 do {
1176 res |= code & 1;
1177 code >>= 1, res <<= 1;
1178 } while (--len > 0);
1179 return res >> 1;
1180 }
1181
1182 /* ===========================================================================
1183 * Flush the bit buffer, keeping at most 7 bits in it.
1184 */
1185 local void bi_flush(s)
1186 deflate_state *s;
1187 {
1188 if (s->bi_valid == 16) {
1189 put_short(s, s->bi_buf);
1190 s->bi_buf = 0;
1191 s->bi_valid = 0;
1192 } else if (s->bi_valid >= 8) {
1193 put_byte(s, (Byte)s->bi_buf);
1194 s->bi_buf >>= 8;
1195 s->bi_valid -= 8;
1196 }
1197 }
1198
1199 /* ===========================================================================
1200 * Flush the bit buffer and align the output on a byte boundary
1201 */
1202 local void bi_windup(s)
1203 deflate_state *s;
1204 {
1205 if (s->bi_valid > 8) {
1206 put_short(s, s->bi_buf);
1207 } else if (s->bi_valid > 0) {
1208 put_byte(s, (Byte)s->bi_buf);
1209 }
1210 s->bi_buf = 0;
1211 s->bi_valid = 0;
1212 #ifdef DEBUG
1213 s->bits_sent = (s->bits_sent+7) & ~7;
1214 #endif
1215 }
1216
1217 /* ===========================================================================
1218 * Copy a stored block, storing first the length and its
1219 * one's complement if requested.
1220 */
1221 local void copy_block(s, buf, len, header)
1222 deflate_state *s;
1223 charf *buf; /* the input data */
1224 unsigned len; /* its length */
1225 int header; /* true if block header must be written */
1226 {
1227 bi_windup(s); /* align on byte boundary */
1228 s->last_eob_len = 8; /* enough lookahead for inflate */
1229
1230 if (header) {
1231 put_short(s, (ush)len);
1232 put_short(s, (ush)~len);
1233 #ifdef DEBUG
1234 s->bits_sent += 2*16;
1235 #endif
1236 }
1237 #ifdef DEBUG
1238 s->bits_sent += (ulg)len<<3;
1239 #endif
1240 while (len--) {
1241 put_byte(s, *buf++);
1242 }
1243 }

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