1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /* trees.c -- output deflated data using Huffman coding
26 * Copyright (C) 1995-2017 Jean-loup Gailly
27 * detect_data_type() function provided freely by Cosmin Truta, 2006
28 * For conditions of distribution and use, see copyright notice in zlib.h
29 */
30
31 /*
32 * ALGORITHM
33 *
34 * The "deflation" process uses several Huffman trees. The more
35 * common source values are represented by shorter bit sequences.
36 *
37 * Each code tree is stored in a compressed form which is itself
38 * a Huffman encoding of the lengths of all the code strings (in
39 * ascending order by source values). The actual code strings are
40 * reconstructed from the lengths in the inflate process, as described
41 * in the deflate specification.
42 *
43 * REFERENCES
44 *
45 * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
46 * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
47 *
48 * Storer, James A.
49 * Data Compression: Methods and Theory, pp. 49-50.
50 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
51 *
52 * Sedgewick, R.
53 * Algorithms, p290.
54 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
55 */
56
57 /* @(#) $Id$ */
58
59 /* #define GEN_TREES_H */
60
61 #include "deflate.h"
62
63 #ifdef ZLIB_DEBUG
64 # include <ctype.h>
65 #endif
66
67 /* ===========================================================================
68 * Constants
69 */
70
71 #define MAX_BL_BITS 7
72 /* Bit length codes must not exceed MAX_BL_BITS bits */
73
74 #define END_BLOCK 256
75 /* end of block literal code */
76
77 #define REP_3_6 16
78 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
79
80 #define REPZ_3_10 17
81 /* repeat a zero length 3-10 times (3 bits of repeat count) */
82
83 #define REPZ_11_138 18
84 /* repeat a zero length 11-138 times (7 bits of repeat count) */
85
86 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
87 = {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};
88
89 local const int extra_dbits[D_CODES] /* extra bits for each distance code */
90 = {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};
91
92 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
93 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
94
95 local const uch bl_order[BL_CODES]
96 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
97 /* The lengths of the bit length codes are sent in order of decreasing
98 * probability, to avoid transmitting the lengths for unused bit length codes.
99 */
100
101 /* ===========================================================================
102 * Local data. These are initialized only once.
103 */
104
105 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
106
107 #if defined(GEN_TREES_H) || !defined(STDC)
108 /* non ANSI compilers may not accept trees.h */
109
110 local ct_data static_ltree[L_CODES+2];
111 /* The static literal tree. Since the bit lengths are imposed, there is no
112 * need for the L_CODES extra codes used during heap construction. However
113 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
114 * below).
115 */
116
117 local ct_data static_dtree[D_CODES];
118 /* The static distance tree. (Actually a trivial tree since all codes use
119 * 5 bits.)
120 */
121
122 uch _dist_code[DIST_CODE_LEN];
123 /* Distance codes. The first 256 values correspond to the distances
124 * 3 .. 258, the last 256 values correspond to the top 8 bits of
125 * the 15 bit distances.
126 */
127
128 uch _length_code[MAX_MATCH-MIN_MATCH+1];
129 /* length code for each normalized match length (0 == MIN_MATCH) */
130
131 local int base_length[LENGTH_CODES];
132 /* First normalized length for each code (0 = MIN_MATCH) */
133
134 local int base_dist[D_CODES];
135 /* First normalized distance for each code (0 = distance of 1) */
136
137 #else
138 # include "trees.h"
139 #endif /* GEN_TREES_H */
140
141 struct static_tree_desc_s {
142 const ct_data *static_tree; /* static tree or NULL */
143 const intf *extra_bits; /* extra bits for each code or NULL */
144 int extra_base; /* base index for extra_bits */
145 int elems; /* max number of elements in the tree */
146 int max_length; /* max bit length for the codes */
147 };
148
149 local const static_tree_desc static_l_desc =
150 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
151
152 local const static_tree_desc static_d_desc =
153 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
154
155 local const static_tree_desc static_bl_desc =
156 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
157
158 /* ===========================================================================
159 * Local (static) routines in this file.
160 */
161
162 local void tr_static_init OF((void));
163 local void init_block OF((deflate_state *s));
164 local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
165 local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
166 local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
167 local void build_tree OF((deflate_state *s, tree_desc *desc));
168 local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
169 local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
170 local int build_bl_tree OF((deflate_state *s));
171 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
172 int blcodes));
173 local void compress_block OF((deflate_state *s, const ct_data *ltree,
174 const ct_data *dtree));
175 local int detect_data_type OF((deflate_state *s));
176 local unsigned bi_reverse OF((unsigned value, int length));
177 local void bi_windup OF((deflate_state *s));
178 local void bi_flush OF((deflate_state *s));
179
180 #ifdef GEN_TREES_H
181 local void gen_trees_header OF((void));
182 #endif
183
184 #ifndef ZLIB_DEBUG
185 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
186 /* Send a code of the given tree. c and tree must not have side effects */
187
188 #else /* !ZLIB_DEBUG */
189 # define send_code(s, c, tree) \
190 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
191 send_bits(s, tree[c].Code, tree[c].Len); }
192 #endif
193
194 /* ===========================================================================
195 * Output a short LSB first on the stream.
196 * IN assertion: there is enough room in pendingBuf.
197 */
198 #define put_short(s, w) { \
199 put_byte(s, (uch)((w) & 0xff)); \
200 put_byte(s, (uch)((ush)(w) >> 8)); \
201 }
202
203 /* ===========================================================================
204 * Send a value on a given number of bits.
205 * IN assertion: length <= 16 and value fits in length bits.
206 */
207 #ifdef ZLIB_DEBUG
208 local void send_bits OF((deflate_state *s, int value, int length));
209
210 local void send_bits(s, value, length)
211 deflate_state *s;
212 int value; /* value to send */
213 int length; /* number of bits */
214 {
215 Tracevv((stderr," l %2d v %4x ", length, value));
216 Assert(length > 0 && length <= 15, "invalid length");
217 s->bits_sent += (ulg)length;
218
219 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
220 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
221 * unused bits in value.
222 */
223 if (s->bi_valid > (int)Buf_size - length) {
224 s->bi_buf |= (ush)value << s->bi_valid;
225 put_short(s, s->bi_buf);
226 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
227 s->bi_valid += length - Buf_size;
228 } else {
229 s->bi_buf |= (ush)value << s->bi_valid;
230 s->bi_valid += length;
231 }
232 }
233 #else /* !ZLIB_DEBUG */
234
235 #define send_bits(s, value, length) \
236 { int len = length;\
237 if (s->bi_valid > (int)Buf_size - len) {\
238 int val = (int)value;\
239 s->bi_buf |= (ush)val << s->bi_valid;\
240 put_short(s, s->bi_buf);\
241 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
242 s->bi_valid += len - Buf_size;\
243 } else {\
244 s->bi_buf |= (ush)(value) << s->bi_valid;\
245 s->bi_valid += len;\
246 }\
247 }
248 #endif /* ZLIB_DEBUG */
249
250
251 /* the arguments must not have side effects */
252
253 /* ===========================================================================
254 * Initialize the various 'constant' tables.
255 */
256 local void tr_static_init()
257 {
258 #if defined(GEN_TREES_H) || !defined(STDC)
259 static int static_init_done = 0;
260 int n; /* iterates over tree elements */
261 int bits; /* bit counter */
262 int length; /* length value */
263 int code; /* code value */
264 int dist; /* distance index */
265 ush bl_count[MAX_BITS+1];
266 /* number of codes at each bit length for an optimal tree */
267
268 if (static_init_done) return;
269
270 /* For some embedded targets, global variables are not initialized: */
271 #ifdef NO_INIT_GLOBAL_POINTERS
272 static_l_desc.static_tree = static_ltree;
273 static_l_desc.extra_bits = extra_lbits;
274 static_d_desc.static_tree = static_dtree;
275 static_d_desc.extra_bits = extra_dbits;
276 static_bl_desc.extra_bits = extra_blbits;
277 #endif
278
279 /* Initialize the mapping length (0..255) -> length code (0..28) */
280 length = 0;
281 for (code = 0; code < LENGTH_CODES-1; code++) {
282 base_length[code] = length;
283 for (n = 0; n < (1<<extra_lbits[code]); n++) {
284 _length_code[length++] = (uch)code;
285 }
286 }
287 Assert (length == 256, "tr_static_init: length != 256");
288 /* Note that the length 255 (match length 258) can be represented
289 * in two different ways: code 284 + 5 bits or code 285, so we
290 * overwrite length_code[255] to use the best encoding:
291 */
292 _length_code[length-1] = (uch)code;
293
294 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
295 dist = 0;
296 for (code = 0 ; code < 16; code++) {
297 base_dist[code] = dist;
298 for (n = 0; n < (1<<extra_dbits[code]); n++) {
299 _dist_code[dist++] = (uch)code;
300 }
301 }
302 Assert (dist == 256, "tr_static_init: dist != 256");
303 dist >>= 7; /* from now on, all distances are divided by 128 */
304 for ( ; code < D_CODES; code++) {
305 base_dist[code] = dist << 7;
306 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
307 _dist_code[256 + dist++] = (uch)code;
308 }
309 }
310 Assert (dist == 256, "tr_static_init: 256+dist != 512");
311
312 /* Construct the codes of the static literal tree */
313 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
314 n = 0;
315 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
316 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
317 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
318 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
319 /* Codes 286 and 287 do not exist, but we must include them in the
320 * tree construction to get a canonical Huffman tree (longest code
321 * all ones)
322 */
323 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
324
325 /* The static distance tree is trivial: */
326 for (n = 0; n < D_CODES; n++) {
327 static_dtree[n].Len = 5;
328 static_dtree[n].Code = bi_reverse((unsigned)n, 5);
329 }
330 static_init_done = 1;
331
332 # ifdef GEN_TREES_H
333 gen_trees_header();
334 # endif
335 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
336 }
337
338 /* ===========================================================================
339 * Genererate the file trees.h describing the static trees.
340 */
341 #ifdef GEN_TREES_H
342 # ifndef ZLIB_DEBUG
343 # include <stdio.h>
344 # endif
345
346 # define SEPARATOR(i, last, width) \
347 ((i) == (last)? "\n};\n\n" : \
348 ((i) % (width) == (width)-1 ? ",\n" : ", "))
349
350 void gen_trees_header()
351 {
352 FILE *header = fopen("trees.h", "w");
353 int i;
354
355 Assert (header != NULL, "Can't open trees.h");
356 fprintf(header,
357 "/* header created automatically with -DGEN_TREES_H */\n\n");
358
359 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
360 for (i = 0; i < L_CODES+2; i++) {
361 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
362 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
363 }
364
365 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
366 for (i = 0; i < D_CODES; i++) {
367 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
368 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
369 }
370
371 fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
372 for (i = 0; i < DIST_CODE_LEN; i++) {
373 fprintf(header, "%2u%s", _dist_code[i],
374 SEPARATOR(i, DIST_CODE_LEN-1, 20));
375 }
376
377 fprintf(header,
378 "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
379 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
380 fprintf(header, "%2u%s", _length_code[i],
381 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
382 }
383
384 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
385 for (i = 0; i < LENGTH_CODES; i++) {
386 fprintf(header, "%1u%s", base_length[i],
387 SEPARATOR(i, LENGTH_CODES-1, 20));
388 }
389
390 fprintf(header, "local const int base_dist[D_CODES] = {\n");
391 for (i = 0; i < D_CODES; i++) {
392 fprintf(header, "%5u%s", base_dist[i],
393 SEPARATOR(i, D_CODES-1, 10));
394 }
395
396 fclose(header);
397 }
398 #endif /* GEN_TREES_H */
399
400 /* ===========================================================================
401 * Initialize the tree data structures for a new zlib stream.
402 */
403 void ZLIB_INTERNAL _tr_init(s)
404 deflate_state *s;
405 {
406 tr_static_init();
407
408 s->l_desc.dyn_tree = s->dyn_ltree;
409 s->l_desc.stat_desc = &static_l_desc;
410
411 s->d_desc.dyn_tree = s->dyn_dtree;
412 s->d_desc.stat_desc = &static_d_desc;
413
414 s->bl_desc.dyn_tree = s->bl_tree;
415 s->bl_desc.stat_desc = &static_bl_desc;
416
417 s->bi_buf = 0;
418 s->bi_valid = 0;
419 #ifdef ZLIB_DEBUG
420 s->compressed_len = 0L;
421 s->bits_sent = 0L;
422 #endif
423
424 /* Initialize the first block of the first file: */
425 init_block(s);
426 }
427
428 /* ===========================================================================
429 * Initialize a new block.
430 */
431 local void init_block(s)
432 deflate_state *s;
433 {
434 int n; /* iterates over tree elements */
435
436 /* Initialize the trees. */
437 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
438 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
439 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
440
441 s->dyn_ltree[END_BLOCK].Freq = 1;
442 s->opt_len = s->static_len = 0L;
443 s->last_lit = s->matches = 0;
444 }
445
446 #define SMALLEST 1
447 /* Index within the heap array of least frequent node in the Huffman tree */
448
449
450 /* ===========================================================================
451 * Remove the smallest element from the heap and recreate the heap with
452 * one less element. Updates heap and heap_len.
453 */
454 #define pqremove(s, tree, top) \
455 {\
456 top = s->heap[SMALLEST]; \
457 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
458 pqdownheap(s, tree, SMALLEST); \
459 }
460
461 /* ===========================================================================
462 * Compares to subtrees, using the tree depth as tie breaker when
463 * the subtrees have equal frequency. This minimizes the worst case length.
464 */
465 #define smaller(tree, n, m, depth) \
466 (tree[n].Freq < tree[m].Freq || \
467 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
468
469 /* ===========================================================================
470 * Restore the heap property by moving down the tree starting at node k,
471 * exchanging a node with the smallest of its two sons if necessary, stopping
472 * when the heap property is re-established (each father smaller than its
473 * two sons).
474 */
475 local void pqdownheap(s, tree, k)
476 deflate_state *s;
477 ct_data *tree; /* the tree to restore */
478 int k; /* node to move down */
479 {
480 int v = s->heap[k];
481 int j = k << 1; /* left son of k */
482 while (j <= s->heap_len) {
483 /* Set j to the smallest of the two sons: */
484 if (j < s->heap_len &&
485 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
486 j++;
487 }
488 /* Exit if v is smaller than both sons */
489 if (smaller(tree, v, s->heap[j], s->depth)) break;
490
491 /* Exchange v with the smallest son */
492 s->heap[k] = s->heap[j]; k = j;
493
494 /* And continue down the tree, setting j to the left son of k */
495 j <<= 1;
496 }
497 s->heap[k] = v;
498 }
499
500 /* ===========================================================================
501 * Compute the optimal bit lengths for a tree and update the total bit length
502 * for the current block.
503 * IN assertion: the fields freq and dad are set, heap[heap_max] and
504 * above are the tree nodes sorted by increasing frequency.
505 * OUT assertions: the field len is set to the optimal bit length, the
506 * array bl_count contains the frequencies for each bit length.
507 * The length opt_len is updated; static_len is also updated if stree is
508 * not null.
509 */
510 local void gen_bitlen(s, desc)
511 deflate_state *s;
512 tree_desc *desc; /* the tree descriptor */
513 {
514 ct_data *tree = desc->dyn_tree;
515 int max_code = desc->max_code;
516 const ct_data *stree = desc->stat_desc->static_tree;
517 const intf *extra = desc->stat_desc->extra_bits;
518 int base = desc->stat_desc->extra_base;
519 int max_length = desc->stat_desc->max_length;
520 int h; /* heap index */
521 int n, m; /* iterate over the tree elements */
522 int bits; /* bit length */
523 int xbits; /* extra bits */
524 ush f; /* frequency */
525 int overflow = 0; /* number of elements with bit length too large */
526
527 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
528
529 /* In a first pass, compute the optimal bit lengths (which may
530 * overflow in the case of the bit length tree).
531 */
532 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
533
534 for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
535 n = s->heap[h];
536 bits = tree[tree[n].Dad].Len + 1;
537 if (bits > max_length) bits = max_length, overflow++;
538 tree[n].Len = (ush)bits;
539 /* We overwrite tree[n].Dad which is no longer needed */
540
541 if (n > max_code) continue; /* not a leaf node */
542
543 s->bl_count[bits]++;
544 xbits = 0;
545 if (n >= base) xbits = extra[n-base];
546 f = tree[n].Freq;
547 s->opt_len += (ulg)f * (unsigned)(bits + xbits);
548 if (stree) s->static_len += (ulg)f * (unsigned)(stree[n].Len + xbits);
549 }
550 if (overflow == 0) return;
551
552 Tracev((stderr,"\nbit length overflow\n"));
553 /* This happens for example on obj2 and pic of the Calgary corpus */
554
555 /* Find the first bit length which could increase: */
556 do {
557 bits = max_length-1;
558 while (s->bl_count[bits] == 0) bits--;
559 s->bl_count[bits]--; /* move one leaf down the tree */
560 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
561 s->bl_count[max_length]--;
562 /* The brother of the overflow item also moves one step up,
563 * but this does not affect bl_count[max_length]
564 */
565 overflow -= 2;
566 } while (overflow > 0);
567
568 /* Now recompute all bit lengths, scanning in increasing frequency.
569 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
570 * lengths instead of fixing only the wrong ones. This idea is taken
571 * from 'ar' written by Haruhiko Okumura.)
572 */
573 for (bits = max_length; bits != 0; bits--) {
574 n = s->bl_count[bits];
575 while (n != 0) {
576 m = s->heap[--h];
577 if (m > max_code) continue;
578 if ((unsigned) tree[m].Len != (unsigned) bits) {
579 Tracev((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
580 s->opt_len += ((ulg)bits - tree[m].Len) * tree[m].Freq;
581 tree[m].Len = (ush)bits;
582 }
583 n--;
584 }
585 }
586 }
587
588 /* ===========================================================================
589 * Generate the codes for a given tree and bit counts (which need not be
590 * optimal).
591 * IN assertion: the array bl_count contains the bit length statistics for
592 * the given tree and the field len is set for all tree elements.
593 * OUT assertion: the field code is set for all tree elements of non
594 * zero code length.
595 */
596 local void gen_codes (tree, max_code, bl_count)
597 ct_data *tree; /* the tree to decorate */
598 int max_code; /* largest code with non zero frequency */
599 ushf *bl_count; /* number of codes at each bit length */
600 {
601 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
602 unsigned code = 0; /* running code value */
603 int bits; /* bit index */
604 int n; /* code index */
605
606 /* The distribution counts are first used to generate the code values
607 * without bit reversal.
608 */
609 for (bits = 1; bits <= MAX_BITS; bits++) {
610 code = (code + bl_count[bits-1]) << 1;
611 next_code[bits] = (ush)code;
612 }
613 /* Check that the bit counts in bl_count are consistent. The last code
614 * must be all ones.
615 */
616 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
617 "inconsistent bit counts");
618 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
619
620 for (n = 0; n <= max_code; n++) {
621 int len = tree[n].Len;
622 if (len == 0) continue;
623 /* Now reverse the bits */
624 tree[n].Code = (ush)bi_reverse(next_code[len]++, len);
625
626 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
627 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
628 }
629 }
630
631 /* ===========================================================================
632 * Construct one Huffman tree and assigns the code bit strings and lengths.
633 * Update the total bit length for the current block.
634 * IN assertion: the field freq is set for all tree elements.
635 * OUT assertions: the fields len and code are set to the optimal bit length
636 * and corresponding code. The length opt_len is updated; static_len is
637 * also updated if stree is not null. The field max_code is set.
638 */
639 local void build_tree(s, desc)
640 deflate_state *s;
641 tree_desc *desc; /* the tree descriptor */
642 {
643 ct_data *tree = desc->dyn_tree;
644 const ct_data *stree = desc->stat_desc->static_tree;
645 int elems = desc->stat_desc->elems;
646 int n, m; /* iterate over heap elements */
647 int max_code = -1; /* largest code with non zero frequency */
648 int node; /* new node being created */
649
650 /* Construct the initial heap, with least frequent element in
651 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
652 * heap[0] is not used.
653 */
654 s->heap_len = 0, s->heap_max = HEAP_SIZE;
655
656 for (n = 0; n < elems; n++) {
657 if (tree[n].Freq != 0) {
658 s->heap[++(s->heap_len)] = max_code = n;
659 s->depth[n] = 0;
660 } else {
661 tree[n].Len = 0;
662 }
663 }
664
665 /* The pkzip format requires that at least one distance code exists,
666 * and that at least one bit should be sent even if there is only one
667 * possible code. So to avoid special checks later on we force at least
668 * two codes of non zero frequency.
669 */
670 while (s->heap_len < 2) {
671 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
672 tree[node].Freq = 1;
673 s->depth[node] = 0;
674 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
675 /* node is 0 or 1 so it does not have extra bits */
676 }
677 desc->max_code = max_code;
678
679 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
680 * establish sub-heaps of increasing lengths:
681 */
682 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
683
684 /* Construct the Huffman tree by repeatedly combining the least two
685 * frequent nodes.
686 */
687 node = elems; /* next internal node of the tree */
688 do {
689 pqremove(s, tree, n); /* n = node of least frequency */
690 m = s->heap[SMALLEST]; /* m = node of next least frequency */
691
692 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
693 s->heap[--(s->heap_max)] = m;
694
695 /* Create a new node father of n and m */
696 tree[node].Freq = tree[n].Freq + tree[m].Freq;
697 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
698 s->depth[n] : s->depth[m]) + 1);
699 tree[n].Dad = tree[m].Dad = (ush)node;
700 #ifdef DUMP_BL_TREE
701 if (tree == s->bl_tree) {
702 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
703 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
704 }
705 #endif
706 /* and insert the new node in the heap */
707 s->heap[SMALLEST] = node++;
708 pqdownheap(s, tree, SMALLEST);
709
710 } while (s->heap_len >= 2);
711
712 s->heap[--(s->heap_max)] = s->heap[SMALLEST];
713
714 /* At this point, the fields freq and dad are set. We can now
715 * generate the bit lengths.
716 */
717 gen_bitlen(s, (tree_desc *)desc);
718
719 /* The field len is now set, we can generate the bit codes */
720 gen_codes ((ct_data *)tree, max_code, s->bl_count);
721 }
722
723 /* ===========================================================================
724 * Scan a literal or distance tree to determine the frequencies of the codes
725 * in the bit length tree.
726 */
727 local void scan_tree (s, tree, max_code)
728 deflate_state *s;
729 ct_data *tree; /* the tree to be scanned */
730 int max_code; /* and its largest code of non zero frequency */
731 {
732 int n; /* iterates over all tree elements */
733 int prevlen = -1; /* last emitted length */
734 int curlen; /* length of current code */
735 int nextlen = tree[0].Len; /* length of next code */
736 int count = 0; /* repeat count of the current code */
737 int max_count = 7; /* max repeat count */
738 int min_count = 4; /* min repeat count */
739
740 if (nextlen == 0) max_count = 138, min_count = 3;
741 tree[max_code+1].Len = (ush)0xffff; /* guard */
742
743 for (n = 0; n <= max_code; n++) {
744 curlen = nextlen; nextlen = tree[n+1].Len;
745 if (++count < max_count && curlen == nextlen) {
746 continue;
747 } else if (count < min_count) {
748 s->bl_tree[curlen].Freq += count;
749 } else if (curlen != 0) {
750 if (curlen != prevlen) s->bl_tree[curlen].Freq++;
751 s->bl_tree[REP_3_6].Freq++;
752 } else if (count <= 10) {
753 s->bl_tree[REPZ_3_10].Freq++;
754 } else {
755 s->bl_tree[REPZ_11_138].Freq++;
756 }
757 count = 0; prevlen = curlen;
758 if (nextlen == 0) {
759 max_count = 138, min_count = 3;
760 } else if (curlen == nextlen) {
761 max_count = 6, min_count = 3;
762 } else {
763 max_count = 7, min_count = 4;
764 }
765 }
766 }
767
768 /* ===========================================================================
769 * Send a literal or distance tree in compressed form, using the codes in
770 * bl_tree.
771 */
772 local void send_tree (s, tree, max_code)
773 deflate_state *s;
774 ct_data *tree; /* the tree to be scanned */
775 int max_code; /* and its largest code of non zero frequency */
776 {
777 int n; /* iterates over all tree elements */
778 int prevlen = -1; /* last emitted length */
779 int curlen; /* length of current code */
780 int nextlen = tree[0].Len; /* length of next code */
781 int count = 0; /* repeat count of the current code */
782 int max_count = 7; /* max repeat count */
783 int min_count = 4; /* min repeat count */
784
785 /* tree[max_code+1].Len = -1; */ /* guard already set */
786 if (nextlen == 0) max_count = 138, min_count = 3;
787
788 for (n = 0; n <= max_code; n++) {
789 curlen = nextlen; nextlen = tree[n+1].Len;
790 if (++count < max_count && curlen == nextlen) {
791 continue;
792 } else if (count < min_count) {
793 do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
794
795 } else if (curlen != 0) {
796 if (curlen != prevlen) {
797 send_code(s, curlen, s->bl_tree); count--;
798 }
799 Assert(count >= 3 && count <= 6, " 3_6?");
800 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
801
802 } else if (count <= 10) {
803 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
804
805 } else {
806 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
807 }
808 count = 0; prevlen = curlen;
809 if (nextlen == 0) {
810 max_count = 138, min_count = 3;
811 } else if (curlen == nextlen) {
812 max_count = 6, min_count = 3;
813 } else {
814 max_count = 7, min_count = 4;
815 }
816 }
817 }
818
819 /* ===========================================================================
820 * Construct the Huffman tree for the bit lengths and return the index in
821 * bl_order of the last bit length code to send.
822 */
823 local int build_bl_tree(s)
824 deflate_state *s;
825 {
826 int max_blindex; /* index of last bit length code of non zero freq */
827
828 /* Determine the bit length frequencies for literal and distance trees */
829 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
830 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
831
832 /* Build the bit length tree: */
833 build_tree(s, (tree_desc *)(&(s->bl_desc)));
834 /* opt_len now includes the length of the tree representations, except
835 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
836 */
837
838 /* Determine the number of bit length codes to send. The pkzip format
839 * requires that at least 4 bit length codes be sent. (appnote.txt says
840 * 3 but the actual value used is 4.)
841 */
842 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
843 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
844 }
845 /* Update opt_len to include the bit length tree and counts */
846 s->opt_len += 3*((ulg)max_blindex+1) + 5+5+4;
847 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
848 s->opt_len, s->static_len));
849
850 return max_blindex;
851 }
852
853 /* ===========================================================================
854 * Send the header for a block using dynamic Huffman trees: the counts, the
855 * lengths of the bit length codes, the literal tree and the distance tree.
856 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
857 */
858 local void send_all_trees(s, lcodes, dcodes, blcodes)
859 deflate_state *s;
860 int lcodes, dcodes, blcodes; /* number of codes for each tree */
861 {
862 int rank; /* index in bl_order */
863
864 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
865 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
866 "too many codes");
867 Tracev((stderr, "\nbl counts: "));
868 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
869 send_bits(s, dcodes-1, 5);
870 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
871 for (rank = 0; rank < blcodes; rank++) {
872 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
873 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
874 }
875 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
876
877 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
878 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
879
880 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
881 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
882 }
883
884 /* ===========================================================================
885 * Send a stored block
886 */
887 void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
888 deflate_state *s;
889 charf *buf; /* input block */
890 ulg stored_len; /* length of input block */
891 int last; /* one if this is the last block for a file */
892 {
893 send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */
894 bi_windup(s); /* align on byte boundary */
895 put_short(s, (ush)stored_len);
896 put_short(s, (ush)~stored_len);
897 zmemcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len);
898 s->pending += stored_len;
899 #ifdef ZLIB_DEBUG
900 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
901 s->compressed_len += (stored_len + 4) << 3;
902 s->bits_sent += 2*16;
903 s->bits_sent += stored_len<<3;
904 #endif
905 }
906
907 /* ===========================================================================
908 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
909 */
910 void ZLIB_INTERNAL _tr_flush_bits(s)
911 deflate_state *s;
912 {
913 bi_flush(s);
914 }
915
916 /* ===========================================================================
917 * Send one empty static block to give enough lookahead for inflate.
918 * This takes 10 bits, of which 7 may remain in the bit buffer.
919 */
920 void ZLIB_INTERNAL _tr_align(s)
921 deflate_state *s;
922 {
923 send_bits(s, STATIC_TREES<<1, 3);
924 send_code(s, END_BLOCK, static_ltree);
925 #ifdef ZLIB_DEBUG
926 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
927 #endif
928 bi_flush(s);
929 }
930
931 /* ===========================================================================
932 * Determine the best encoding for the current block: dynamic trees, static
933 * trees or store, and write out the encoded block.
934 */
935 void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
936 deflate_state *s;
937 charf *buf; /* input block, or NULL if too old */
938 ulg stored_len; /* length of input block */
939 int last; /* one if this is the last block for a file */
940 {
941 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
942 int max_blindex = 0; /* index of last bit length code of non zero freq */
943
944 /* Build the Huffman trees unless a stored block is forced */
945 if (s->level > 0) {
946
947 /* Check if the file is binary or text */
948 if (s->strm->data_type == Z_UNKNOWN)
949 s->strm->data_type = detect_data_type(s);
950
951 /* Construct the literal and distance trees */
952 build_tree(s, (tree_desc *)(&(s->l_desc)));
953 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
954 s->static_len));
955
956 build_tree(s, (tree_desc *)(&(s->d_desc)));
957 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
958 s->static_len));
959 /* At this point, opt_len and static_len are the total bit lengths of
960 * the compressed block data, excluding the tree representations.
961 */
962
963 /* Build the bit length tree for the above two trees, and get the index
964 * in bl_order of the last bit length code to send.
965 */
966 max_blindex = build_bl_tree(s);
967
968 /* Determine the best encoding. Compute the block lengths in bytes. */
969 opt_lenb = (s->opt_len+3+7)>>3;
970 static_lenb = (s->static_len+3+7)>>3;
971
972 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
973 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
974 s->last_lit));
975
976 if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
977
978 } else {
979 Assert(buf != (char*)0, "lost buf");
980 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
981 }
982
983 #ifdef FORCE_STORED
984 if (buf != (char*)0) { /* force stored block */
985 #else
986 if (stored_len+4 <= opt_lenb && buf != (char*)0) {
987 /* 4: two words for the lengths */
988 #endif
989 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
990 * Otherwise we can't have processed more than WSIZE input bytes since
991 * the last block flush, because compression would have been
992 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
993 * transform a block into a stored block.
994 */
995 _tr_stored_block(s, buf, stored_len, last);
996
997 #ifdef FORCE_STATIC
998 } else if (static_lenb >= 0) { /* force static trees */
999 #else
1000 } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
1001 #endif
1002 send_bits(s, (STATIC_TREES<<1)+last, 3);
1003 compress_block(s, (const ct_data *)static_ltree,
1004 (const ct_data *)static_dtree);
1005 #ifdef ZLIB_DEBUG
1006 s->compressed_len += 3 + s->static_len;
1007 #endif
1008 } else {
1009 send_bits(s, (DYN_TREES<<1)+last, 3);
1010 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
1011 max_blindex+1);
1012 compress_block(s, (const ct_data *)s->dyn_ltree,
1013 (const ct_data *)s->dyn_dtree);
1014 #ifdef ZLIB_DEBUG
1015 s->compressed_len += 3 + s->opt_len;
1016 #endif
1017 }
1018 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1019 /* The above check is made mod 2^32, for files larger than 512 MB
1020 * and uLong implemented on 32 bits.
1021 */
1022 init_block(s);
1023
1024 if (last) {
1025 bi_windup(s);
1026 #ifdef ZLIB_DEBUG
1027 s->compressed_len += 7; /* align on byte boundary */
1028 #endif
1029 }
1030 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1031 s->compressed_len-7*last));
1032 }
1033
1034 /* ===========================================================================
1035 * Save the match info and tally the frequency counts. Return true if
1036 * the current block must be flushed.
1037 */
1038 int ZLIB_INTERNAL _tr_tally (s, dist, lc)
1039 deflate_state *s;
1040 unsigned dist; /* distance of matched string */
1041 unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1042 {
1043 s->d_buf[s->last_lit] = (ush)dist;
1044 s->l_buf[s->last_lit++] = (uch)lc;
1045 if (dist == 0) {
1046 /* lc is the unmatched char */
1047 s->dyn_ltree[lc].Freq++;
1048 } else {
1049 s->matches++;
1050 /* Here, lc is the match length - MIN_MATCH */
1051 dist--; /* dist = match distance - 1 */
1052 Assert((ush)dist < (ush)MAX_DIST(s) &&
1053 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1054 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1055
1056 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1057 s->dyn_dtree[d_code(dist)].Freq++;
1058 }
1059
1060 #ifdef TRUNCATE_BLOCK
1061 /* Try to guess if it is profitable to stop the current block here */
1062 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1063 /* Compute an upper bound for the compressed length */
1064 ulg out_length = (ulg)s->last_lit*8L;
1065 ulg in_length = (ulg)((long)s->strstart - s->block_start);
1066 int dcode;
1067 for (dcode = 0; dcode < D_CODES; dcode++) {
1068 out_length += (ulg)s->dyn_dtree[dcode].Freq *
1069 (5L+extra_dbits[dcode]);
1070 }
1071 out_length >>= 3;
1072 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1073 s->last_lit, in_length, out_length,
1074 100L - out_length*100L/in_length));
1075 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1076 }
1077 #endif
1078 return (s->last_lit == s->lit_bufsize-1);
1079 /* We avoid equality with lit_bufsize because of wraparound at 64K
1080 * on 16 bit machines and because stored blocks are restricted to
1081 * 64K-1 bytes.
1082 */
1083 }
1084
1085 /* ===========================================================================
1086 * Send the block data compressed using the given Huffman trees
1087 */
1088 local void compress_block(s, ltree, dtree)
1089 deflate_state *s;
1090 const ct_data *ltree; /* literal tree */
1091 const ct_data *dtree; /* distance tree */
1092 {
1093 unsigned dist; /* distance of matched string */
1094 int lc; /* match length or unmatched char (if dist == 0) */
1095 unsigned lx = 0; /* running index in l_buf */
1096 unsigned code; /* the code to send */
1097 int extra; /* number of extra bits to send */
1098
1099 if (s->last_lit != 0) do {
1100 dist = s->d_buf[lx];
1101 lc = s->l_buf[lx++];
1102 if (dist == 0) {
1103 send_code(s, lc, ltree); /* send a literal byte */
1104 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1105 } else {
1106 /* Here, lc is the match length - MIN_MATCH */
1107 code = _length_code[lc];
1108 send_code(s, code+LITERALS+1, ltree); /* send the length code */
1109 extra = extra_lbits[code];
1110 if (extra != 0) {
1111 lc -= base_length[code];
1112 send_bits(s, lc, extra); /* send the extra length bits */
1113 }
1114 dist--; /* dist is now the match distance - 1 */
1115 code = d_code(dist);
1116 Assert (code < D_CODES, "bad d_code");
1117
1118 send_code(s, code, dtree); /* send the distance code */
1119 extra = extra_dbits[code];
1120 if (extra != 0) {
1121 dist -= (unsigned)base_dist[code];
1122 send_bits(s, dist, extra); /* send the extra distance bits */
1123 }
1124 } /* literal or match pair ? */
1125
1126 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1127 Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1128 "pendingBuf overflow");
1129
1130 } while (lx < s->last_lit);
1131
1132 send_code(s, END_BLOCK, ltree);
1133 }
1134
1135 /* ===========================================================================
1136 * Check if the data type is TEXT or BINARY, using the following algorithm:
1137 * - TEXT if the two conditions below are satisfied:
1138 * a) There are no non-portable control characters belonging to the
1139 * "black list" (0..6, 14..25, 28..31).
1140 * b) There is at least one printable character belonging to the
1141 * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1142 * - BINARY otherwise.
1143 * - The following partially-portable control characters form a
1144 * "gray list" that is ignored in this detection algorithm:
1145 * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1146 * IN assertion: the fields Freq of dyn_ltree are set.
1147 */
1148 local int detect_data_type(s)
1149 deflate_state *s;
1150 {
1151 /* black_mask is the bit mask of black-listed bytes
1152 * set bits 0..6, 14..25, and 28..31
1153 * 0xf3ffc07f = binary 11110011111111111100000001111111
1154 */
1155 unsigned long black_mask = 0xf3ffc07fUL;
1156 int n;
1157
1158 /* Check for non-textual ("black-listed") bytes. */
1159 for (n = 0; n <= 31; n++, black_mask >>= 1)
1160 if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1161 return Z_BINARY;
1162
1163 /* Check for textual ("white-listed") bytes. */
1164 if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1165 || s->dyn_ltree[13].Freq != 0)
1166 return Z_TEXT;
1167 for (n = 32; n < LITERALS; n++)
1168 if (s->dyn_ltree[n].Freq != 0)
1169 return Z_TEXT;
1170
1171 /* There are no "black-listed" or "white-listed" bytes:
1172 * this stream either is empty or has tolerated ("gray-listed") bytes only.
1173 */
1174 return Z_BINARY;
1175 }
1176
1177 /* ===========================================================================
1178 * Reverse the first len bits of a code, using straightforward code (a faster
1179 * method would use a table)
1180 * IN assertion: 1 <= len <= 15
1181 */
1182 local unsigned bi_reverse(code, len)
1183 unsigned code; /* the value to invert */
1184 int len; /* its bit length */
1185 {
1186 register unsigned res = 0;
1187 do {
1188 res |= code & 1;
1189 code >>= 1, res <<= 1;
1190 } while (--len > 0);
1191 return res >> 1;
1192 }
1193
1194 /* ===========================================================================
1195 * Flush the bit buffer, keeping at most 7 bits in it.
1196 */
1197 local void bi_flush(s)
1198 deflate_state *s;
1199 {
1200 if (s->bi_valid == 16) {
1201 put_short(s, s->bi_buf);
1202 s->bi_buf = 0;
1203 s->bi_valid = 0;
1204 } else if (s->bi_valid >= 8) {
1205 put_byte(s, (Byte)s->bi_buf);
1206 s->bi_buf >>= 8;
1207 s->bi_valid -= 8;
1208 }
1209 }
1210
1211 /* ===========================================================================
1212 * Flush the bit buffer and align the output on a byte boundary
1213 */
1214 local void bi_windup(s)
1215 deflate_state *s;
1216 {
1217 if (s->bi_valid > 8) {
1218 put_short(s, s->bi_buf);
1219 } else if (s->bi_valid > 0) {
1220 put_byte(s, (Byte)s->bi_buf);
1221 }
1222 s->bi_buf = 0;
1223 s->bi_valid = 0;
1224 #ifdef ZLIB_DEBUG
1225 s->bits_sent = (s->bits_sent+7) & ~7;
1226 #endif
1227 }