1 /* trees.c -- output deflated data using Huffman coding
2 * Copyright (C) 1995-2010 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 /* #define GEN_TREES_H */
34
35 #include "deflate.h"
36
37 #ifdef DEBUG
38 # include <ctype.h>
39 #endif
40
41 /* ===========================================================================
42 * Constants
43 */
44
45 #define MAX_BL_BITS 7
46 /* Bit length codes must not exceed MAX_BL_BITS bits */
47
48 #define END_BLOCK 256
49 /* end of block literal code */
50
51 #define REP_3_6 16
52 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
53
54 #define REPZ_3_10 17
55 /* repeat a zero length 3-10 times (3 bits of repeat count) */
56
57 #define REPZ_11_138 18
58 /* repeat a zero length 11-138 times (7 bits of repeat count) */
59
60 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
61 = {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};
62
63 local const int extra_dbits[D_CODES] /* extra bits for each distance code */
64 = {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};
65
66 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
67 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
68
69 local const uch bl_order[BL_CODES]
70 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
71 /* The lengths of the bit length codes are sent in order of decreasing
72 * probability, to avoid transmitting the lengths for unused bit length codes.
73 */
74
75 #define Buf_size (8 * 2*sizeof(char))
76 /* Number of bits used within bi_buf. (bi_buf might be implemented on
77 * more than 16 bits on some systems.)
78 */
79
80 /* ===========================================================================
81 * Local data. These are initialized only once.
82 */
83
84 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
85
86 #if defined(GEN_TREES_H) || !defined(STDC)
87 /* non ANSI compilers may not accept trees.h */
88
89 local ct_data static_ltree[L_CODES+2];
90 /* The static literal tree. Since the bit lengths are imposed, there is no
91 * need for the L_CODES extra codes used during heap construction. However
92 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
93 * below).
94 */
95
96 local ct_data static_dtree[D_CODES];
97 /* The static distance tree. (Actually a trivial tree since all codes use
98 * 5 bits.)
99 */
100
101 uch _dist_code[DIST_CODE_LEN];
102 /* Distance codes. The first 256 values correspond to the distances
103 * 3 .. 258, the last 256 values correspond to the top 8 bits of
104 * the 15 bit distances.
105 */
106
107 uch _length_code[MAX_MATCH-MIN_MATCH+1];
108 /* length code for each normalized match length (0 == MIN_MATCH) */
109
110 local int base_length[LENGTH_CODES];
111 /* First normalized length for each code (0 = MIN_MATCH) */
112
113 local int base_dist[D_CODES];
114 /* First normalized distance for each code (0 = distance of 1) */
115
116 #else
117 # include "trees.h"
118 #endif /* GEN_TREES_H */
119
120 struct static_tree_desc_s {
121 const ct_data *static_tree; /* static tree or NULL */
122 const intf *extra_bits; /* extra bits for each code or NULL */
123 int extra_base; /* base index for extra_bits */
124 int elems; /* max number of elements in the tree */
125 int max_length; /* max bit length for the codes */
126 };
127
128 local static_tree_desc static_l_desc =
129 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
130
131 local static_tree_desc static_d_desc =
132 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
133
134 local static_tree_desc static_bl_desc =
135 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
136
137 /* ===========================================================================
138 * Local (static) routines in this file.
139 */
140
141 local void tr_static_init OF((void));
142 local void init_block OF((deflate_state *s));
143 local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
144 local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
145 local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
146 local void build_tree OF((deflate_state *s, tree_desc *desc));
147 local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
148 local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
149 local int build_bl_tree OF((deflate_state *s));
150 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
151 int blcodes));
152 local void compress_block OF((deflate_state *s, ct_data *ltree,
153 ct_data *dtree));
154 local int detect_data_type OF((deflate_state *s));
155 local unsigned bi_reverse OF((unsigned value, int length));
156 local void bi_windup OF((deflate_state *s));
157 local void bi_flush OF((deflate_state *s));
158 local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
159 int header));
160
161 #ifdef GEN_TREES_H
162 local void gen_trees_header OF((void));
163 #endif
164
165 #ifndef DEBUG
166 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
167 /* Send a code of the given tree. c and tree must not have side effects */
168
169 #else /* DEBUG */
170 # define send_code(s, c, tree) \
171 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
172 send_bits(s, tree[c].Code, tree[c].Len); }
173 #endif
174
175 /* ===========================================================================
176 * Output a short LSB first on the stream.
177 * IN assertion: there is enough room in pendingBuf.
178 */
179 #define put_short(s, w) { \
180 put_byte(s, (uch)((w) & 0xff)); \
181 put_byte(s, (uch)((ush)(w) >> 8)); \
182 }
183
184 /* ===========================================================================
185 * Send a value on a given number of bits.
186 * IN assertion: length <= 16 and value fits in length bits.
187 */
188 #ifdef DEBUG
189 local void send_bits OF((deflate_state *s, int value, int length));
190
send_bits(s,value,length)191 local void send_bits(s, value, length)
192 deflate_state *s;
193 int value; /* value to send */
194 int length; /* number of bits */
195 {
196 Tracevv((stderr," l %2d v %4x ", length, value));
197 Assert(length > 0 && length <= 15, "invalid length");
198 s->bits_sent += (ulg)length;
199
200 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
201 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
202 * unused bits in value.
203 */
204 if (s->bi_valid > (int)Buf_size - length) {
205 s->bi_buf |= (ush)value << s->bi_valid;
206 put_short(s, s->bi_buf);
207 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
208 s->bi_valid += length - Buf_size;
209 } else {
210 s->bi_buf |= (ush)value << s->bi_valid;
211 s->bi_valid += length;
212 }
213 }
214 #else /* !DEBUG */
215
216 #define send_bits(s, value, length) \
217 { int len = length;\
218 if (s->bi_valid > (int)Buf_size - len) {\
219 int val = value;\
220 s->bi_buf |= (ush)val << s->bi_valid;\
221 put_short(s, s->bi_buf);\
222 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
223 s->bi_valid += len - Buf_size;\
224 } else {\
225 s->bi_buf |= (ush)(value) << s->bi_valid;\
226 s->bi_valid += len;\
227 }\
228 }
229 #endif /* DEBUG */
230
231
232 /* the arguments must not have side effects */
233
234 /* ===========================================================================
235 * Initialize the various 'constant' tables.
236 */
tr_static_init()237 local void tr_static_init()
238 {
239 #if defined(GEN_TREES_H) || !defined(STDC)
240 static int static_init_done = 0;
241 int n; /* iterates over tree elements */
242 int bits; /* bit counter */
243 int length; /* length value */
244 int code; /* code value */
245 int dist; /* distance index */
246 ush bl_count[MAX_BITS+1];
247 /* number of codes at each bit length for an optimal tree */
248
249 if (static_init_done) return;
250
251 /* For some embedded targets, global variables are not initialized: */
252 #ifdef NO_INIT_GLOBAL_POINTERS
253 static_l_desc.static_tree = static_ltree;
254 static_l_desc.extra_bits = extra_lbits;
255 static_d_desc.static_tree = static_dtree;
256 static_d_desc.extra_bits = extra_dbits;
257 static_bl_desc.extra_bits = extra_blbits;
258 #endif
259
260 /* Initialize the mapping length (0..255) -> length code (0..28) */
261 length = 0;
262 for (code = 0; code < LENGTH_CODES-1; code++) {
263 base_length[code] = length;
264 for (n = 0; n < (1<<extra_lbits[code]); n++) {
265 _length_code[length++] = (uch)code;
266 }
267 }
268 Assert (length == 256, "tr_static_init: length != 256");
269 /* Note that the length 255 (match length 258) can be represented
270 * in two different ways: code 284 + 5 bits or code 285, so we
271 * overwrite length_code[255] to use the best encoding:
272 */
273 _length_code[length-1] = (uch)code;
274
275 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
276 dist = 0;
277 for (code = 0 ; code < 16; code++) {
278 base_dist[code] = dist;
279 for (n = 0; n < (1<<extra_dbits[code]); n++) {
280 _dist_code[dist++] = (uch)code;
281 }
282 }
283 Assert (dist == 256, "tr_static_init: dist != 256");
284 dist >>= 7; /* from now on, all distances are divided by 128 */
285 for ( ; code < D_CODES; code++) {
286 base_dist[code] = dist << 7;
287 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
288 _dist_code[256 + dist++] = (uch)code;
289 }
290 }
291 Assert (dist == 256, "tr_static_init: 256+dist != 512");
292
293 /* Construct the codes of the static literal tree */
294 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
295 n = 0;
296 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
297 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
298 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
299 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
300 /* Codes 286 and 287 do not exist, but we must include them in the
301 * tree construction to get a canonical Huffman tree (longest code
302 * all ones)
303 */
304 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
305
306 /* The static distance tree is trivial: */
307 for (n = 0; n < D_CODES; n++) {
308 static_dtree[n].Len = 5;
309 static_dtree[n].Code = bi_reverse((unsigned)n, 5);
310 }
311 static_init_done = 1;
312
313 # ifdef GEN_TREES_H
314 gen_trees_header();
315 # endif
316 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
317 }
318
319 /* ===========================================================================
320 * Genererate the file trees.h describing the static trees.
321 */
322 #ifdef GEN_TREES_H
323 # ifndef DEBUG
324 # include <stdio.h>
325 # endif
326
327 # define SEPARATOR(i, last, width) \
328 ((i) == (last)? "\n};\n\n" : \
329 ((i) % (width) == (width)-1 ? ",\n" : ", "))
330
gen_trees_header()331 void gen_trees_header()
332 {
333 FILE *header = fopen("trees.h", "w");
334 int i;
335
336 Assert (header != NULL, "Can't open trees.h");
337 fprintf(header,
338 "/* header created automatically with -DGEN_TREES_H */\n\n");
339
340 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
341 for (i = 0; i < L_CODES+2; i++) {
342 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
343 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
344 }
345
346 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
347 for (i = 0; i < D_CODES; i++) {
348 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
349 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
350 }
351
352 fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
353 for (i = 0; i < DIST_CODE_LEN; i++) {
354 fprintf(header, "%2u%s", _dist_code[i],
355 SEPARATOR(i, DIST_CODE_LEN-1, 20));
356 }
357
358 fprintf(header,
359 "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
360 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
361 fprintf(header, "%2u%s", _length_code[i],
362 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
363 }
364
365 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
366 for (i = 0; i < LENGTH_CODES; i++) {
367 fprintf(header, "%1u%s", base_length[i],
368 SEPARATOR(i, LENGTH_CODES-1, 20));
369 }
370
371 fprintf(header, "local const int base_dist[D_CODES] = {\n");
372 for (i = 0; i < D_CODES; i++) {
373 fprintf(header, "%5u%s", base_dist[i],
374 SEPARATOR(i, D_CODES-1, 10));
375 }
376
377 fclose(header);
378 }
379 #endif /* GEN_TREES_H */
380
381 /* ===========================================================================
382 * Initialize the tree data structures for a new zlib stream.
383 */
_tr_init(s)384 void ZLIB_INTERNAL _tr_init(s)
385 deflate_state *s;
386 {
387 tr_static_init();
388
389 s->l_desc.dyn_tree = s->dyn_ltree;
390 s->l_desc.stat_desc = &static_l_desc;
391
392 s->d_desc.dyn_tree = s->dyn_dtree;
393 s->d_desc.stat_desc = &static_d_desc;
394
395 s->bl_desc.dyn_tree = s->bl_tree;
396 s->bl_desc.stat_desc = &static_bl_desc;
397
398 s->bi_buf = 0;
399 s->bi_valid = 0;
400 s->last_eob_len = 8; /* enough lookahead for inflate */
401 #ifdef DEBUG
402 s->compressed_len = 0L;
403 s->bits_sent = 0L;
404 #endif
405
406 /* Initialize the first block of the first file: */
407 init_block(s);
408 }
409
410 /* ===========================================================================
411 * Initialize a new block.
412 */
init_block(s)413 local void init_block(s)
414 deflate_state *s;
415 {
416 int n; /* iterates over tree elements */
417
418 /* Initialize the trees. */
419 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
420 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
421 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
422
423 s->dyn_ltree[END_BLOCK].Freq = 1;
424 s->opt_len = s->static_len = 0L;
425 s->last_lit = s->matches = 0;
426 }
427
428 #define SMALLEST 1
429 /* Index within the heap array of least frequent node in the Huffman tree */
430
431
432 /* ===========================================================================
433 * Remove the smallest element from the heap and recreate the heap with
434 * one less element. Updates heap and heap_len.
435 */
436 #define pqremove(s, tree, top) \
437 {\
438 top = s->heap[SMALLEST]; \
439 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
440 pqdownheap(s, tree, SMALLEST); \
441 }
442
443 /* ===========================================================================
444 * Compares to subtrees, using the tree depth as tie breaker when
445 * the subtrees have equal frequency. This minimizes the worst case length.
446 */
447 #define smaller(tree, n, m, depth) \
448 (tree[n].Freq < tree[m].Freq || \
449 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
450
451 /* ===========================================================================
452 * Restore the heap property by moving down the tree starting at node k,
453 * exchanging a node with the smallest of its two sons if necessary, stopping
454 * when the heap property is re-established (each father smaller than its
455 * two sons).
456 */
pqdownheap(s,tree,k)457 local void pqdownheap(s, tree, k)
458 deflate_state *s;
459 ct_data *tree; /* the tree to restore */
460 int k; /* node to move down */
461 {
462 int v = s->heap[k];
463 int j = k << 1; /* left son of k */
464 while (j <= s->heap_len) {
465 /* Set j to the smallest of the two sons: */
466 if (j < s->heap_len &&
467 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
468 j++;
469 }
470 /* Exit if v is smaller than both sons */
471 if (smaller(tree, v, s->heap[j], s->depth)) break;
472
473 /* Exchange v with the smallest son */
474 s->heap[k] = s->heap[j]; k = j;
475
476 /* And continue down the tree, setting j to the left son of k */
477 j <<= 1;
478 }
479 s->heap[k] = v;
480 }
481
482 /* ===========================================================================
483 * Compute the optimal bit lengths for a tree and update the total bit length
484 * for the current block.
485 * IN assertion: the fields freq and dad are set, heap[heap_max] and
486 * above are the tree nodes sorted by increasing frequency.
487 * OUT assertions: the field len is set to the optimal bit length, the
488 * array bl_count contains the frequencies for each bit length.
489 * The length opt_len is updated; static_len is also updated if stree is
490 * not null.
491 */
gen_bitlen(s,desc)492 local void gen_bitlen(s, desc)
493 deflate_state *s;
494 tree_desc *desc; /* the tree descriptor */
495 {
496 ct_data *tree = desc->dyn_tree;
497 int max_code = desc->max_code;
498 const ct_data *stree = desc->stat_desc->static_tree;
499 const intf *extra = desc->stat_desc->extra_bits;
500 int base = desc->stat_desc->extra_base;
501 int max_length = desc->stat_desc->max_length;
502 int h; /* heap index */
503 int n, m; /* iterate over the tree elements */
504 int bits; /* bit length */
505 int xbits; /* extra bits */
506 ush f; /* frequency */
507 int overflow = 0; /* number of elements with bit length too large */
508
509 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
510
511 /* In a first pass, compute the optimal bit lengths (which may
512 * overflow in the case of the bit length tree).
513 */
514 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
515
516 for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
517 n = s->heap[h];
518 bits = tree[tree[n].Dad].Len + 1;
519 if (bits > max_length) bits = max_length, overflow++;
520 tree[n].Len = (ush)bits;
521 /* We overwrite tree[n].Dad which is no longer needed */
522
523 if (n > max_code) continue; /* not a leaf node */
524
525 s->bl_count[bits]++;
526 xbits = 0;
527 if (n >= base) xbits = extra[n-base];
528 f = tree[n].Freq;
529 s->opt_len += (ulg)f * (bits + xbits);
530 if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
531 }
532 if (overflow == 0) return;
533
534 Trace((stderr,"\nbit length overflow\n"));
535 /* This happens for example on obj2 and pic of the Calgary corpus */
536
537 /* Find the first bit length which could increase: */
538 do {
539 bits = max_length-1;
540 while (s->bl_count[bits] == 0) bits--;
541 s->bl_count[bits]--; /* move one leaf down the tree */
542 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
543 s->bl_count[max_length]--;
544 /* The brother of the overflow item also moves one step up,
545 * but this does not affect bl_count[max_length]
546 */
547 overflow -= 2;
548 } while (overflow > 0);
549
550 /* Now recompute all bit lengths, scanning in increasing frequency.
551 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
552 * lengths instead of fixing only the wrong ones. This idea is taken
553 * from 'ar' written by Haruhiko Okumura.)
554 */
555 for (bits = max_length; bits != 0; bits--) {
556 n = s->bl_count[bits];
557 while (n != 0) {
558 m = s->heap[--h];
559 if (m > max_code) continue;
560 if ((unsigned) tree[m].Len != (unsigned) bits) {
561 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
562 s->opt_len += ((long)bits - (long)tree[m].Len)
563 *(long)tree[m].Freq;
564 tree[m].Len = (ush)bits;
565 }
566 n--;
567 }
568 }
569 }
570
571 /* ===========================================================================
572 * Generate the codes for a given tree and bit counts (which need not be
573 * optimal).
574 * IN assertion: the array bl_count contains the bit length statistics for
575 * the given tree and the field len is set for all tree elements.
576 * OUT assertion: the field code is set for all tree elements of non
577 * zero code length.
578 */
gen_codes(tree,max_code,bl_count)579 local void gen_codes (tree, max_code, bl_count)
580 ct_data *tree; /* the tree to decorate */
581 int max_code; /* largest code with non zero frequency */
582 ushf *bl_count; /* number of codes at each bit length */
583 {
584 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
585 ush code = 0; /* running code value */
586 int bits; /* bit index */
587 int n; /* code index */
588
589 /* The distribution counts are first used to generate the code values
590 * without bit reversal.
591 */
592 for (bits = 1; bits <= MAX_BITS; bits++) {
593 next_code[bits] = code = (code + bl_count[bits-1]) << 1;
594 }
595 /* Check that the bit counts in bl_count are consistent. The last code
596 * must be all ones.
597 */
598 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
599 "inconsistent bit counts");
600 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
601
602 for (n = 0; n <= max_code; n++) {
603 int len = tree[n].Len;
604 if (len == 0) continue;
605 /* Now reverse the bits */
606 tree[n].Code = bi_reverse(next_code[len]++, len);
607
608 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
609 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
610 }
611 }
612
613 /* ===========================================================================
614 * Construct one Huffman tree and assigns the code bit strings and lengths.
615 * Update the total bit length for the current block.
616 * IN assertion: the field freq is set for all tree elements.
617 * OUT assertions: the fields len and code are set to the optimal bit length
618 * and corresponding code. The length opt_len is updated; static_len is
619 * also updated if stree is not null. The field max_code is set.
620 */
build_tree(s,desc)621 local void build_tree(s, desc)
622 deflate_state *s;
623 tree_desc *desc; /* the tree descriptor */
624 {
625 ct_data *tree = desc->dyn_tree;
626 const ct_data *stree = desc->stat_desc->static_tree;
627 int elems = desc->stat_desc->elems;
628 int n, m; /* iterate over heap elements */
629 int max_code = -1; /* largest code with non zero frequency */
630 int node; /* new node being created */
631
632 /* Construct the initial heap, with least frequent element in
633 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
634 * heap[0] is not used.
635 */
636 s->heap_len = 0, s->heap_max = HEAP_SIZE;
637
638 for (n = 0; n < elems; n++) {
639 if (tree[n].Freq != 0) {
640 s->heap[++(s->heap_len)] = max_code = n;
641 s->depth[n] = 0;
642 } else {
643 tree[n].Len = 0;
644 }
645 }
646
647 /* The pkzip format requires that at least one distance code exists,
648 * and that at least one bit should be sent even if there is only one
649 * possible code. So to avoid special checks later on we force at least
650 * two codes of non zero frequency.
651 */
652 while (s->heap_len < 2) {
653 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
654 tree[node].Freq = 1;
655 s->depth[node] = 0;
656 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
657 /* node is 0 or 1 so it does not have extra bits */
658 }
659 desc->max_code = max_code;
660
661 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
662 * establish sub-heaps of increasing lengths:
663 */
664 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
665
666 /* Construct the Huffman tree by repeatedly combining the least two
667 * frequent nodes.
668 */
669 node = elems; /* next internal node of the tree */
670 do {
671 pqremove(s, tree, n); /* n = node of least frequency */
672 m = s->heap[SMALLEST]; /* m = node of next least frequency */
673
674 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
675 s->heap[--(s->heap_max)] = m;
676
677 /* Create a new node father of n and m */
678 tree[node].Freq = tree[n].Freq + tree[m].Freq;
679 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
680 s->depth[n] : s->depth[m]) + 1);
681 tree[n].Dad = tree[m].Dad = (ush)node;
682 #ifdef DUMP_BL_TREE
683 if (tree == s->bl_tree) {
684 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
685 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
686 }
687 #endif
688 /* and insert the new node in the heap */
689 s->heap[SMALLEST] = node++;
690 pqdownheap(s, tree, SMALLEST);
691
692 } while (s->heap_len >= 2);
693
694 s->heap[--(s->heap_max)] = s->heap[SMALLEST];
695
696 /* At this point, the fields freq and dad are set. We can now
697 * generate the bit lengths.
698 */
699 gen_bitlen(s, (tree_desc *)desc);
700
701 /* The field len is now set, we can generate the bit codes */
702 gen_codes ((ct_data *)tree, max_code, s->bl_count);
703 }
704
705 /* ===========================================================================
706 * Scan a literal or distance tree to determine the frequencies of the codes
707 * in the bit length tree.
708 */
scan_tree(s,tree,max_code)709 local void scan_tree (s, tree, max_code)
710 deflate_state *s;
711 ct_data *tree; /* the tree to be scanned */
712 int max_code; /* and its largest code of non zero frequency */
713 {
714 int n; /* iterates over all tree elements */
715 int prevlen = -1; /* last emitted length */
716 int curlen; /* length of current code */
717 int nextlen = tree[0].Len; /* length of next code */
718 int count = 0; /* repeat count of the current code */
719 int max_count = 7; /* max repeat count */
720 int min_count = 4; /* min repeat count */
721
722 if (nextlen == 0) max_count = 138, min_count = 3;
723 tree[max_code+1].Len = (ush)0xffff; /* guard */
724
725 for (n = 0; n <= max_code; n++) {
726 curlen = nextlen; nextlen = tree[n+1].Len;
727 if (++count < max_count && curlen == nextlen) {
728 continue;
729 } else if (count < min_count) {
730 s->bl_tree[curlen].Freq += count;
731 } else if (curlen != 0) {
732 if (curlen != prevlen) s->bl_tree[curlen].Freq++;
733 s->bl_tree[REP_3_6].Freq++;
734 } else if (count <= 10) {
735 s->bl_tree[REPZ_3_10].Freq++;
736 } else {
737 s->bl_tree[REPZ_11_138].Freq++;
738 }
739 count = 0; prevlen = curlen;
740 if (nextlen == 0) {
741 max_count = 138, min_count = 3;
742 } else if (curlen == nextlen) {
743 max_count = 6, min_count = 3;
744 } else {
745 max_count = 7, min_count = 4;
746 }
747 }
748 }
749
750 /* ===========================================================================
751 * Send a literal or distance tree in compressed form, using the codes in
752 * bl_tree.
753 */
send_tree(s,tree,max_code)754 local void send_tree (s, tree, max_code)
755 deflate_state *s;
756 ct_data *tree; /* the tree to be scanned */
757 int max_code; /* and its largest code of non zero frequency */
758 {
759 int n; /* iterates over all tree elements */
760 int prevlen = -1; /* last emitted length */
761 int curlen; /* length of current code */
762 int nextlen = tree[0].Len; /* length of next code */
763 int count = 0; /* repeat count of the current code */
764 int max_count = 7; /* max repeat count */
765 int min_count = 4; /* min repeat count */
766
767 /* tree[max_code+1].Len = -1; */ /* guard already set */
768 if (nextlen == 0) max_count = 138, min_count = 3;
769
770 for (n = 0; n <= max_code; n++) {
771 curlen = nextlen; nextlen = tree[n+1].Len;
772 if (++count < max_count && curlen == nextlen) {
773 continue;
774 } else if (count < min_count) {
775 do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
776
777 } else if (curlen != 0) {
778 if (curlen != prevlen) {
779 send_code(s, curlen, s->bl_tree); count--;
780 }
781 Assert(count >= 3 && count <= 6, " 3_6?");
782 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
783
784 } else if (count <= 10) {
785 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
786
787 } else {
788 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
789 }
790 count = 0; prevlen = curlen;
791 if (nextlen == 0) {
792 max_count = 138, min_count = 3;
793 } else if (curlen == nextlen) {
794 max_count = 6, min_count = 3;
795 } else {
796 max_count = 7, min_count = 4;
797 }
798 }
799 }
800
801 /* ===========================================================================
802 * Construct the Huffman tree for the bit lengths and return the index in
803 * bl_order of the last bit length code to send.
804 */
build_bl_tree(s)805 local int build_bl_tree(s)
806 deflate_state *s;
807 {
808 int max_blindex; /* index of last bit length code of non zero freq */
809
810 /* Determine the bit length frequencies for literal and distance trees */
811 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
812 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
813
814 /* Build the bit length tree: */
815 build_tree(s, (tree_desc *)(&(s->bl_desc)));
816 /* opt_len now includes the length of the tree representations, except
817 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
818 */
819
820 /* Determine the number of bit length codes to send. The pkzip format
821 * requires that at least 4 bit length codes be sent. (appnote.txt says
822 * 3 but the actual value used is 4.)
823 */
824 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
825 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
826 }
827 /* Update opt_len to include the bit length tree and counts */
828 s->opt_len += 3*(max_blindex+1) + 5+5+4;
829 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
830 s->opt_len, s->static_len));
831
832 return max_blindex;
833 }
834
835 /* ===========================================================================
836 * Send the header for a block using dynamic Huffman trees: the counts, the
837 * lengths of the bit length codes, the literal tree and the distance tree.
838 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
839 */
send_all_trees(s,lcodes,dcodes,blcodes)840 local void send_all_trees(s, lcodes, dcodes, blcodes)
841 deflate_state *s;
842 int lcodes, dcodes, blcodes; /* number of codes for each tree */
843 {
844 int rank; /* index in bl_order */
845
846 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
847 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
848 "too many codes");
849 Tracev((stderr, "\nbl counts: "));
850 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
851 send_bits(s, dcodes-1, 5);
852 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
853 for (rank = 0; rank < blcodes; rank++) {
854 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
855 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
856 }
857 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
858
859 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
860 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
861
862 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
863 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
864 }
865
866 /* ===========================================================================
867 * Send a stored block
868 */
_tr_stored_block(s,buf,stored_len,last)869 void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
870 deflate_state *s;
871 charf *buf; /* input block */
872 ulg stored_len; /* length of input block */
873 int last; /* one if this is the last block for a file */
874 {
875 send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */
876 #ifdef DEBUG
877 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
878 s->compressed_len += (stored_len + 4) << 3;
879 #endif
880 copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
881 }
882
883 /* ===========================================================================
884 * Send one empty static block to give enough lookahead for inflate.
885 * This takes 10 bits, of which 7 may remain in the bit buffer.
886 * The current inflate code requires 9 bits of lookahead. If the
887 * last two codes for the previous block (real code plus EOB) were coded
888 * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
889 * the last real code. In this case we send two empty static blocks instead
890 * of one. (There are no problems if the previous block is stored or fixed.)
891 * To simplify the code, we assume the worst case of last real code encoded
892 * on one bit only.
893 */
_tr_align(s)894 void ZLIB_INTERNAL _tr_align(s)
895 deflate_state *s;
896 {
897 send_bits(s, STATIC_TREES<<1, 3);
898 send_code(s, END_BLOCK, static_ltree);
899 #ifdef DEBUG
900 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
901 #endif
902 bi_flush(s);
903 /* Of the 10 bits for the empty block, we have already sent
904 * (10 - bi_valid) bits. The lookahead for the last real code (before
905 * the EOB of the previous block) was thus at least one plus the length
906 * of the EOB plus what we have just sent of the empty static block.
907 */
908 if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
909 send_bits(s, STATIC_TREES<<1, 3);
910 send_code(s, END_BLOCK, static_ltree);
911 #ifdef DEBUG
912 s->compressed_len += 10L;
913 #endif
914 bi_flush(s);
915 }
916 s->last_eob_len = 7;
917 }
918
919 /* ===========================================================================
920 * Determine the best encoding for the current block: dynamic trees, static
921 * trees or store, and output the encoded block to the zip file.
922 */
_tr_flush_block(s,buf,stored_len,last)923 void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
924 deflate_state *s;
925 charf *buf; /* input block, or NULL if too old */
926 ulg stored_len; /* length of input block */
927 int last; /* one if this is the last block for a file */
928 {
929 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
930 int max_blindex = 0; /* index of last bit length code of non zero freq */
931
932 /* Build the Huffman trees unless a stored block is forced */
933 if (s->level > 0) {
934
935 /* Check if the file is binary or text */
936 if (s->strm->data_type == Z_UNKNOWN)
937 s->strm->data_type = detect_data_type(s);
938
939 /* Construct the literal and distance trees */
940 build_tree(s, (tree_desc *)(&(s->l_desc)));
941 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
942 s->static_len));
943
944 build_tree(s, (tree_desc *)(&(s->d_desc)));
945 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
946 s->static_len));
947 /* At this point, opt_len and static_len are the total bit lengths of
948 * the compressed block data, excluding the tree representations.
949 */
950
951 /* Build the bit length tree for the above two trees, and get the index
952 * in bl_order of the last bit length code to send.
953 */
954 max_blindex = build_bl_tree(s);
955
956 /* Determine the best encoding. Compute the block lengths in bytes. */
957 opt_lenb = (s->opt_len+3+7)>>3;
958 static_lenb = (s->static_len+3+7)>>3;
959
960 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
961 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
962 s->last_lit));
963
964 if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
965
966 } else {
967 Assert(buf != (char*)0, "lost buf");
968 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
969 }
970
971 #ifdef FORCE_STORED
972 if (buf != (char*)0) { /* force stored block */
973 #else
974 if (stored_len+4 <= opt_lenb && buf != (char*)0) {
975 /* 4: two words for the lengths */
976 #endif
977 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
978 * Otherwise we can't have processed more than WSIZE input bytes since
979 * the last block flush, because compression would have been
980 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
981 * transform a block into a stored block.
982 */
983 _tr_stored_block(s, buf, stored_len, last);
984
985 #ifdef FORCE_STATIC
986 } else if (static_lenb >= 0) { /* force static trees */
987 #else
988 } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
989 #endif
990 send_bits(s, (STATIC_TREES<<1)+last, 3);
991 compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
992 #ifdef DEBUG
993 s->compressed_len += 3 + s->static_len;
994 #endif
995 } else {
996 send_bits(s, (DYN_TREES<<1)+last, 3);
997 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
998 max_blindex+1);
999 compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
1000 #ifdef DEBUG
1001 s->compressed_len += 3 + s->opt_len;
1002 #endif
1003 }
1004 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1005 /* The above check is made mod 2^32, for files larger than 512 MB
1006 * and uLong implemented on 32 bits.
1007 */
1008 init_block(s);
1009
1010 if (last) {
1011 bi_windup(s);
1012 #ifdef DEBUG
1013 s->compressed_len += 7; /* align on byte boundary */
1014 #endif
1015 }
1016 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1017 s->compressed_len-7*last));
1018 }
1019
1020 /* ===========================================================================
1021 * Save the match info and tally the frequency counts. Return true if
1022 * the current block must be flushed.
1023 */
_tr_tally(s,dist,lc)1024 int ZLIB_INTERNAL _tr_tally (s, dist, lc)
1025 deflate_state *s;
1026 unsigned dist; /* distance of matched string */
1027 unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1028 {
1029 s->d_buf[s->last_lit] = (ush)dist;
1030 s->l_buf[s->last_lit++] = (uch)lc;
1031 if (dist == 0) {
1032 /* lc is the unmatched char */
1033 s->dyn_ltree[lc].Freq++;
1034 } else {
1035 s->matches++;
1036 /* Here, lc is the match length - MIN_MATCH */
1037 dist--; /* dist = match distance - 1 */
1038 Assert((ush)dist < (ush)MAX_DIST(s) &&
1039 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1040 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1041
1042 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1043 s->dyn_dtree[d_code(dist)].Freq++;
1044 }
1045
1046 #ifdef TRUNCATE_BLOCK
1047 /* Try to guess if it is profitable to stop the current block here */
1048 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1049 /* Compute an upper bound for the compressed length */
1050 ulg out_length = (ulg)s->last_lit*8L;
1051 ulg in_length = (ulg)((long)s->strstart - s->block_start);
1052 int dcode;
1053 for (dcode = 0; dcode < D_CODES; dcode++) {
1054 out_length += (ulg)s->dyn_dtree[dcode].Freq *
1055 (5L+extra_dbits[dcode]);
1056 }
1057 out_length >>= 3;
1058 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1059 s->last_lit, in_length, out_length,
1060 100L - out_length*100L/in_length));
1061 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1062 }
1063 #endif
1064 return (s->last_lit == s->lit_bufsize-1);
1065 /* We avoid equality with lit_bufsize because of wraparound at 64K
1066 * on 16 bit machines and because stored blocks are restricted to
1067 * 64K-1 bytes.
1068 */
1069 }
1070
1071 /* ===========================================================================
1072 * Send the block data compressed using the given Huffman trees
1073 */
compress_block(s,ltree,dtree)1074 local void compress_block(s, ltree, dtree)
1075 deflate_state *s;
1076 ct_data *ltree; /* literal tree */
1077 ct_data *dtree; /* distance tree */
1078 {
1079 unsigned dist; /* distance of matched string */
1080 int lc; /* match length or unmatched char (if dist == 0) */
1081 unsigned lx = 0; /* running index in l_buf */
1082 unsigned code; /* the code to send */
1083 int extra; /* number of extra bits to send */
1084
1085 if (s->last_lit != 0) do {
1086 dist = s->d_buf[lx];
1087 lc = s->l_buf[lx++];
1088 if (dist == 0) {
1089 send_code(s, lc, ltree); /* send a literal byte */
1090 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1091 } else {
1092 /* Here, lc is the match length - MIN_MATCH */
1093 code = _length_code[lc];
1094 send_code(s, code+LITERALS+1, ltree); /* send the length code */
1095 extra = extra_lbits[code];
1096 if (extra != 0) {
1097 lc -= base_length[code];
1098 send_bits(s, lc, extra); /* send the extra length bits */
1099 }
1100 dist--; /* dist is now the match distance - 1 */
1101 code = d_code(dist);
1102 Assert (code < D_CODES, "bad d_code");
1103
1104 send_code(s, code, dtree); /* send the distance code */
1105 extra = extra_dbits[code];
1106 if (extra != 0) {
1107 dist -= base_dist[code];
1108 send_bits(s, dist, extra); /* send the extra distance bits */
1109 }
1110 } /* literal or match pair ? */
1111
1112 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1113 Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1114 "pendingBuf overflow");
1115
1116 } while (lx < s->last_lit);
1117
1118 send_code(s, END_BLOCK, ltree);
1119 s->last_eob_len = ltree[END_BLOCK].Len;
1120 }
1121
1122 /* ===========================================================================
1123 * Check if the data type is TEXT or BINARY, using the following algorithm:
1124 * - TEXT if the two conditions below are satisfied:
1125 * a) There are no non-portable control characters belonging to the
1126 * "black list" (0..6, 14..25, 28..31).
1127 * b) There is at least one printable character belonging to the
1128 * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1129 * - BINARY otherwise.
1130 * - The following partially-portable control characters form a
1131 * "gray list" that is ignored in this detection algorithm:
1132 * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1133 * IN assertion: the fields Freq of dyn_ltree are set.
1134 */
detect_data_type(s)1135 local int detect_data_type(s)
1136 deflate_state *s;
1137 {
1138 /* black_mask is the bit mask of black-listed bytes
1139 * set bits 0..6, 14..25, and 28..31
1140 * 0xf3ffc07f = binary 11110011111111111100000001111111
1141 */
1142 unsigned long black_mask = 0xf3ffc07fUL;
1143 int n;
1144
1145 /* Check for non-textual ("black-listed") bytes. */
1146 for (n = 0; n <= 31; n++, black_mask >>= 1)
1147 if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1148 return Z_BINARY;
1149
1150 /* Check for textual ("white-listed") bytes. */
1151 if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1152 || s->dyn_ltree[13].Freq != 0)
1153 return Z_TEXT;
1154 for (n = 32; n < LITERALS; n++)
1155 if (s->dyn_ltree[n].Freq != 0)
1156 return Z_TEXT;
1157
1158 /* There are no "black-listed" or "white-listed" bytes:
1159 * this stream either is empty or has tolerated ("gray-listed") bytes only.
1160 */
1161 return Z_BINARY;
1162 }
1163
1164 /* ===========================================================================
1165 * Reverse the first len bits of a code, using straightforward code (a faster
1166 * method would use a table)
1167 * IN assertion: 1 <= len <= 15
1168 */
bi_reverse(code,len)1169 local unsigned bi_reverse(code, len)
1170 unsigned code; /* the value to invert */
1171 int len; /* its bit length */
1172 {
1173 register unsigned res = 0;
1174 do {
1175 res |= code & 1;
1176 code >>= 1, res <<= 1;
1177 } while (--len > 0);
1178 return res >> 1;
1179 }
1180
1181 /* ===========================================================================
1182 * Flush the bit buffer, keeping at most 7 bits in it.
1183 */
bi_flush(s)1184 local void bi_flush(s)
1185 deflate_state *s;
1186 {
1187 if (s->bi_valid == 16) {
1188 put_short(s, s->bi_buf);
1189 s->bi_buf = 0;
1190 s->bi_valid = 0;
1191 } else if (s->bi_valid >= 8) {
1192 put_byte(s, (Byte)s->bi_buf);
1193 s->bi_buf >>= 8;
1194 s->bi_valid -= 8;
1195 }
1196 }
1197
1198 /* ===========================================================================
1199 * Flush the bit buffer and align the output on a byte boundary
1200 */
bi_windup(s)1201 local void bi_windup(s)
1202 deflate_state *s;
1203 {
1204 if (s->bi_valid > 8) {
1205 put_short(s, s->bi_buf);
1206 } else if (s->bi_valid > 0) {
1207 put_byte(s, (Byte)s->bi_buf);
1208 }
1209 s->bi_buf = 0;
1210 s->bi_valid = 0;
1211 #ifdef DEBUG
1212 s->bits_sent = (s->bits_sent+7) & ~7;
1213 #endif
1214 }
1215
1216 /* ===========================================================================
1217 * Copy a stored block, storing first the length and its
1218 * one's complement if requested.
1219 */
copy_block(s,buf,len,header)1220 local void copy_block(s, buf, len, header)
1221 deflate_state *s;
1222 charf *buf; /* the input data */
1223 unsigned len; /* its length */
1224 int header; /* true if block header must be written */
1225 {
1226 bi_windup(s); /* align on byte boundary */
1227 s->last_eob_len = 8; /* enough lookahead for inflate */
1228
1229 if (header) {
1230 put_short(s, (ush)len);
1231 put_short(s, (ush)~len);
1232 #ifdef DEBUG
1233 s->bits_sent += 2*16;
1234 #endif
1235 }
1236 #ifdef DEBUG
1237 s->bits_sent += (ulg)len<<3;
1238 #endif
1239 while (len--) {
1240 put_byte(s, *buf++);
1241 }
1242 }
1243