1 /* +++ trees.c */ 1
2 /* trees.c -- output deflated data using Huffm
3 * Copyright (C) 1995-1996 Jean-loup Gailly
4 * For conditions of distribution and use, see
5 */
6
7 /*
8 * ALGORITHM
9 *
10 * The "deflation" process uses several H
11 * common source values are represented b
12 *
13 * Each code tree is stored in a compress
14 * a Huffman encoding of the lengths of all th
15 * ascending order by source values). The act
16 * reconstructed from the lengths in the infla
17 * in the deflate specification.
18 *
19 * REFERENCES
20 *
21 * Deutsch, L.P.,"'Deflate' Compressed Da
22 * Available in ftp.uu.net:/pub/archiving
23 *
24 * Storer, James A.
25 * Data Compression: Methods and The
26 * Computer Science Press, 1988. ISB
27 *
28 * Sedgewick, R.
29 * Algorithms, p290.
30 * Addison-Wesley, 1983. ISBN 0-201-0
31 */
32
33 /* From: trees.c,v 1.11 1996/07/24 13:41:06 me
34
35 /* #include "deflate.h" */
36
37 #include <linux/zutil.h>
38 #include <linux/bitrev.h>
39 #include "defutil.h"
40
41 #ifdef DEBUG_ZLIB
42 # include <ctype.h>
43 #endif
44
45 /* ===========================================
46 * Constants
47 */
48
49 #define MAX_BL_BITS 7
50 /* Bit length codes must not exceed MAX_BL_BIT
51
52 #define END_BLOCK 256
53 /* end of block literal code */
54
55 #define REP_3_6 16
56 /* repeat previous bit length 3-6 times (2 bit
57
58 #define REPZ_3_10 17
59 /* repeat a zero length 3-10 times (3 bits of
60
61 #define REPZ_11_138 18
62 /* repeat a zero length 11-138 times (7 bits
63
64 static const int extra_lbits[LENGTH_CODES] /*
65 = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,
66
67 static const int extra_dbits[D_CODES] /* extra
68 = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,
69
70 static const int extra_blbits[BL_CODES]/* extr
71 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
72
73 static const uch bl_order[BL_CODES]
74 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,1
75 /* The lengths of the bit length codes are sen
76 * probability, to avoid transmitting the leng
77 */
78
79 /* ===========================================
80 * Local data. These are initialized only once
81 */
82
83 static ct_data static_ltree[L_CODES+2];
84 /* The static literal tree. Since the bit leng
85 * need for the L_CODES extra codes used durin
86 * The codes 286 and 287 are needed to build a
87 * below).
88 */
89
90 static ct_data static_dtree[D_CODES];
91 /* The static distance tree. (Actually a trivi
92 * 5 bits.)
93 */
94
95 static uch dist_code[512];
96 /* distance codes. The first 256 values corres
97 * 3 .. 258, the last 256 values correspond to
98 * the 15 bit distances.
99 */
100
101 static uch length_code[MAX_MATCH-MIN_MATCH+1];
102 /* length code for each normalized match lengt
103
104 static int base_length[LENGTH_CODES];
105 /* First normalized length for each code (0 =
106
107 static int base_dist[D_CODES];
108 /* First normalized distance for each code (0
109
110 struct static_tree_desc_s {
111 const ct_data *static_tree; /* static tre
112 const int *extra_bits; /* extra bits
113 int extra_base; /* base index
114 int elems; /* max number
115 int max_length; /* max bit le
116 };
117
118 static static_tree_desc static_l_desc =
119 {static_ltree, extra_lbits, LITERALS+1, L_CODE
120
121 static static_tree_desc static_d_desc =
122 {static_dtree, extra_dbits, 0, D_CODE
123
124 static static_tree_desc static_bl_desc =
125 {(const ct_data *)0, extra_blbits, 0, BL_COD
126
127 /* ===========================================
128 * Local (static) routines in this file.
129 */
130
131 static void tr_static_init (void);
132 static void init_block (deflate_state *s);
133 static void pqdownheap (deflate_state *s,
134 static void gen_bitlen (deflate_state *s,
135 static void gen_codes (ct_data *tree, int
136 static void build_tree (deflate_state *s,
137 static void scan_tree (deflate_state *s,
138 static void send_tree (deflate_state *s,
139 static int build_bl_tree (deflate_state *s);
140 static void send_all_trees (deflate_state *s,
141 int blcodes);
142 static void compress_block (deflate_state *s,
143 ct_data *dtree);
144 static void set_data_type (deflate_state *s);
145 static void bi_flush (deflate_state *s);
146 static void copy_block (deflate_state *s,
147 int header);
148
149 #ifndef DEBUG_ZLIB
150 # define send_code(s, c, tree) send_bits(s, t
151 /* Send a code of the given tree. c and tre
152
153 #else /* DEBUG_ZLIB */
154 # define send_code(s, c, tree) \
155 { if (z_verbose>2) fprintf(stderr,"\ncd %
156 send_bits(s, tree[c].Code, tree[c].Len)
157 #endif
158
159 #define d_code(dist) \
160 ((dist) < 256 ? dist_code[dist] : dist_code
161 /* Mapping from a distance to a distance code.
162 * must not have side effects. dist_code[256]
163 * used.
164 */
165
166 /* ===========================================
167 * Initialize the various 'constant' tables. I
168 * this function may be called by two threads
169 * harmless since both invocations do exactly
170 */
171 static void tr_static_init(void)
172 {
173 static int static_init_done;
174 int n; /* iterates over tree elemen
175 int bits; /* bit counter */
176 int length; /* length value */
177 int code; /* code value */
178 int dist; /* distance index */
179 ush bl_count[MAX_BITS+1];
180 /* number of codes at each bit length for
181
182 if (static_init_done) return;
183
184 /* Initialize the mapping length (0..255)
185 length = 0;
186 for (code = 0; code < LENGTH_CODES-1; code
187 base_length[code] = length;
188 for (n = 0; n < (1<<extra_lbits[code])
189 length_code[length++] = (uch)code;
190 }
191 }
192 Assert (length == 256, "tr_static_init: le
193 /* Note that the length 255 (match length
194 * in two different ways: code 284 + 5 bit
195 * overwrite length_code[255] to use the b
196 */
197 length_code[length-1] = (uch)code;
198
199 /* Initialize the mapping dist (0..32K) ->
200 dist = 0;
201 for (code = 0 ; code < 16; code++) {
202 base_dist[code] = dist;
203 for (n = 0; n < (1<<extra_dbits[code])
204 dist_code[dist++] = (uch)code;
205 }
206 }
207 Assert (dist == 256, "tr_static_init: dist
208 dist >>= 7; /* from now on, all distances
209 for ( ; code < D_CODES; code++) {
210 base_dist[code] = dist << 7;
211 for (n = 0; n < (1<<(extra_dbits[code]
212 dist_code[256 + dist++] = (uch)cod
213 }
214 }
215 Assert (dist == 256, "tr_static_init: 256+
216
217 /* Construct the codes of the static liter
218 for (bits = 0; bits <= MAX_BITS; bits++) b
219 n = 0;
220 while (n <= 143) static_ltree[n++].Len = 8
221 while (n <= 255) static_ltree[n++].Len = 9
222 while (n <= 279) static_ltree[n++].Len = 7
223 while (n <= 287) static_ltree[n++].Len = 8
224 /* Codes 286 and 287 do not exist, but we
225 * tree construction to get a canonical Hu
226 * all ones)
227 */
228 gen_codes((ct_data *)static_ltree, L_CODES
229
230 /* The static distance tree is trivial: */
231 for (n = 0; n < D_CODES; n++) {
232 static_dtree[n].Len = 5;
233 static_dtree[n].Code = bitrev32((u32)n
234 }
235 static_init_done = 1;
236 }
237
238 /* ===========================================
239 * Initialize the tree data structures for a n
240 */
241 void zlib_tr_init(
242 deflate_state *s
243 )
244 {
245 tr_static_init();
246
247 s->compressed_len = 0L;
248
249 s->l_desc.dyn_tree = s->dyn_ltree;
250 s->l_desc.stat_desc = &static_l_desc;
251
252 s->d_desc.dyn_tree = s->dyn_dtree;
253 s->d_desc.stat_desc = &static_d_desc;
254
255 s->bl_desc.dyn_tree = s->bl_tree;
256 s->bl_desc.stat_desc = &static_bl_desc;
257
258 s->bi_buf = 0;
259 s->bi_valid = 0;
260 s->last_eob_len = 8; /* enough lookahead f
261 #ifdef DEBUG_ZLIB
262 s->bits_sent = 0L;
263 #endif
264
265 /* Initialize the first block of the first
266 init_block(s);
267 }
268
269 /* ===========================================
270 * Initialize a new block.
271 */
272 static void init_block(
273 deflate_state *s
274 )
275 {
276 int n; /* iterates over tree elements */
277
278 /* Initialize the trees. */
279 for (n = 0; n < L_CODES; n++) s->dyn_ltre
280 for (n = 0; n < D_CODES; n++) s->dyn_dtre
281 for (n = 0; n < BL_CODES; n++) s->bl_tree[
282
283 s->dyn_ltree[END_BLOCK].Freq = 1;
284 s->opt_len = s->static_len = 0L;
285 s->last_lit = s->matches = 0;
286 }
287
288 #define SMALLEST 1
289 /* Index within the heap array of least freque
290
291
292 /* ===========================================
293 * Remove the smallest element from the heap a
294 * one less element. Updates heap and heap_len
295 */
296 #define pqremove(s, tree, top) \
297 {\
298 top = s->heap[SMALLEST]; \
299 s->heap[SMALLEST] = s->heap[s->heap_len--]
300 pqdownheap(s, tree, SMALLEST); \
301 }
302
303 /* ===========================================
304 * Compares to subtrees, using the tree depth
305 * the subtrees have equal frequency. This min
306 */
307 #define smaller(tree, n, m, depth) \
308 (tree[n].Freq < tree[m].Freq || \
309 (tree[n].Freq == tree[m].Freq && depth[n] <
310
311 /* ===========================================
312 * Restore the heap property by moving down th
313 * exchanging a node with the smallest of its
314 * when the heap property is re-established (e
315 * two sons).
316 */
317 static void pqdownheap(
318 deflate_state *s,
319 ct_data *tree, /* the tree to restore
320 int k /* node to move down *
321 )
322 {
323 int v = s->heap[k];
324 int j = k << 1; /* left son of k */
325 while (j <= s->heap_len) {
326 /* Set j to the smallest of the two so
327 if (j < s->heap_len &&
328 smaller(tree, s->heap[j+1], s->hea
329 j++;
330 }
331 /* Exit if v is smaller than both sons
332 if (smaller(tree, v, s->heap[j], s->de
333
334 /* Exchange v with the smallest son */
335 s->heap[k] = s->heap[j]; k = j;
336
337 /* And continue down the tree, setting
338 j <<= 1;
339 }
340 s->heap[k] = v;
341 }
342
343 /* ===========================================
344 * Compute the optimal bit lengths for a tree
345 * for the current block.
346 * IN assertion: the fields freq and dad are s
347 * above are the tree nodes sorted by incre
348 * OUT assertions: the field len is set to the
349 * array bl_count contains the frequencies
350 * The length opt_len is updated; static_l
351 * not null.
352 */
353 static void gen_bitlen(
354 deflate_state *s,
355 tree_desc *desc /* the tree descrip
356 )
357 {
358 ct_data *tree = desc->dyn_tree;
359 int max_code = desc->max_code;
360 const ct_data *stree = desc->stat_desc->st
361 const int *extra = desc->stat_desc->ex
362 int base = desc->stat_desc->ex
363 int max_length = desc->stat_desc->ma
364 int h; /* heap index */
365 int n, m; /* iterate over the tr
366 int bits; /* bit length */
367 int xbits; /* extra bits */
368 ush f; /* frequency */
369 int overflow = 0; /* number of elements
370
371 for (bits = 0; bits <= MAX_BITS; bits++) s
372
373 /* In a first pass, compute the optimal bi
374 * overflow in the case of the bit length
375 */
376 tree[s->heap[s->heap_max]].Len = 0; /* roo
377
378 for (h = s->heap_max+1; h < HEAP_SIZE; h++
379 n = s->heap[h];
380 bits = tree[tree[n].Dad].Len + 1;
381 if (bits > max_length) bits = max_leng
382 tree[n].Len = (ush)bits;
383 /* We overwrite tree[n].Dad which is n
384
385 if (n > max_code) continue; /* not a l
386
387 s->bl_count[bits]++;
388 xbits = 0;
389 if (n >= base) xbits = extra[n-base];
390 f = tree[n].Freq;
391 s->opt_len += (ulg)f * (bits + xbits);
392 if (stree) s->static_len += (ulg)f * (
393 }
394 if (overflow == 0) return;
395
396 Trace((stderr,"\nbit length overflow\n"));
397 /* This happens for example on obj2 and pi
398
399 /* Find the first bit length which could i
400 do {
401 bits = max_length-1;
402 while (s->bl_count[bits] == 0) bits--;
403 s->bl_count[bits]--; /* move one
404 s->bl_count[bits+1] += 2; /* move one
405 s->bl_count[max_length]--;
406 /* The brother of the overflow item al
407 * but this does not affect bl_count[m
408 */
409 overflow -= 2;
410 } while (overflow > 0);
411
412 /* Now recompute all bit lengths, scanning
413 * h is still equal to HEAP_SIZE. (It is s
414 * lengths instead of fixing only the wron
415 * from 'ar' written by Haruhiko Okumura.)
416 */
417 for (bits = max_length; bits != 0; bits--)
418 n = s->bl_count[bits];
419 while (n != 0) {
420 m = s->heap[--h];
421 if (m > max_code) continue;
422 if (tree[m].Len != (unsigned) bits
423 Trace((stderr,"code %d bits %d
424 s->opt_len += ((long)bits - (l
425 *(long)tree[m].F
426 tree[m].Len = (ush)bits;
427 }
428 n--;
429 }
430 }
431 }
432
433 /* ===========================================
434 * Generate the codes for a given tree and bit
435 * optimal).
436 * IN assertion: the array bl_count contains t
437 * the given tree and the field len is set for
438 * OUT assertion: the field code is set for al
439 * zero code length.
440 */
441 static void gen_codes(
442 ct_data *tree, /* the tree
443 int max_code, /* largest
444 ush *bl_count /* number of
445 )
446 {
447 ush next_code[MAX_BITS+1]; /* next code va
448 ush code = 0; /* running code
449 int bits; /* bit index */
450 int n; /* code index *
451
452 /* The distribution counts are first used
453 * without bit reversal.
454 */
455 for (bits = 1; bits <= MAX_BITS; bits++) {
456 next_code[bits] = code = (code + bl_co
457 }
458 /* Check that the bit counts in bl_count a
459 * must be all ones.
460 */
461 Assert (code + bl_count[MAX_BITS]-1 == (1<
462 "inconsistent bit counts");
463 Tracev((stderr,"\ngen_codes: max_code %d "
464
465 for (n = 0; n <= max_code; n++) {
466 int len = tree[n].Len;
467 if (len == 0) continue;
468 /* Now reverse the bits */
469 tree[n].Code = bitrev32((u32)(next_cod
470
471 Tracecv(tree != static_ltree, (stderr,
472 n, (isgraph(n) ? n : ' '), len, t
473 }
474 }
475
476 /* ===========================================
477 * Construct one Huffman tree and assigns the
478 * Update the total bit length for the current
479 * IN assertion: the field freq is set for all
480 * OUT assertions: the fields len and code are
481 * and corresponding code. The length opt_
482 * also updated if stree is not null. The
483 */
484 static void build_tree(
485 deflate_state *s,
486 tree_desc *desc /* the tree descripto
487 )
488 {
489 ct_data *tree = desc->dyn_tree;
490 const ct_data *stree = desc->stat_desc->s
491 int elems = desc->stat_desc->e
492 int n, m; /* iterate over heap el
493 int max_code = -1; /* largest code with no
494 int node; /* new node being creat
495
496 /* Construct the initial heap, with least
497 * heap[SMALLEST]. The sons of heap[n] are
498 * heap[0] is not used.
499 */
500 s->heap_len = 0, s->heap_max = HEAP_SIZE;
501
502 for (n = 0; n < elems; n++) {
503 if (tree[n].Freq != 0) {
504 s->heap[++(s->heap_len)] = max_cod
505 s->depth[n] = 0;
506 } else {
507 tree[n].Len = 0;
508 }
509 }
510
511 /* The pkzip format requires that at least
512 * and that at least one bit should be sen
513 * possible code. So to avoid special chec
514 * two codes of non zero frequency.
515 */
516 while (s->heap_len < 2) {
517 node = s->heap[++(s->heap_len)] = (max
518 tree[node].Freq = 1;
519 s->depth[node] = 0;
520 s->opt_len--; if (stree) s->static_len
521 /* node is 0 or 1 so it does not have
522 }
523 desc->max_code = max_code;
524
525 /* The elements heap[heap_len/2+1 .. heap_
526 * establish sub-heaps of increasing lengt
527 */
528 for (n = s->heap_len/2; n >= 1; n--) pqdow
529
530 /* Construct the Huffman tree by repeatedl
531 * frequent nodes.
532 */
533 node = elems; /* next interna
534 do {
535 pqremove(s, tree, n); /* n = node of
536 m = s->heap[SMALLEST]; /* m = node of
537
538 s->heap[--(s->heap_max)] = n; /* keep
539 s->heap[--(s->heap_max)] = m;
540
541 /* Create a new node father of n and m
542 tree[node].Freq = tree[n].Freq + tree[
543 s->depth[node] = (uch) (max(s->depth[n
544 tree[n].Dad = tree[m].Dad = (ush)node;
545 #ifdef DUMP_BL_TREE
546 if (tree == s->bl_tree) {
547 fprintf(stderr,"\nnode %d(%d), son
548 node, tree[node].Freq, n,
549 }
550 #endif
551 /* and insert the new node in the heap
552 s->heap[SMALLEST] = node++;
553 pqdownheap(s, tree, SMALLEST);
554
555 } while (s->heap_len >= 2);
556
557 s->heap[--(s->heap_max)] = s->heap[SMALLES
558
559 /* At this point, the fields freq and dad
560 * generate the bit lengths.
561 */
562 gen_bitlen(s, (tree_desc *)desc);
563
564 /* The field len is now set, we can genera
565 gen_codes ((ct_data *)tree, max_code, s->b
566 }
567
568 /* ===========================================
569 * Scan a literal or distance tree to determin
570 * in the bit length tree.
571 */
572 static void scan_tree(
573 deflate_state *s,
574 ct_data *tree, /* the tree to be sca
575 int max_code /* and its largest co
576 )
577 {
578 int n; /* iterates ove
579 int prevlen = -1; /* last emitted
580 int curlen; /* length of cu
581 int nextlen = tree[0].Len; /* length of ne
582 int count = 0; /* repeat count
583 int max_count = 7; /* max repeat c
584 int min_count = 4; /* min repeat c
585
586 if (nextlen == 0) max_count = 138, min_cou
587 tree[max_code+1].Len = (ush)0xffff; /* gua
588
589 for (n = 0; n <= max_code; n++) {
590 curlen = nextlen; nextlen = tree[n+1].
591 if (++count < max_count && curlen == n
592 continue;
593 } else if (count < min_count) {
594 s->bl_tree[curlen].Freq += count;
595 } else if (curlen != 0) {
596 if (curlen != prevlen) s->bl_tree[
597 s->bl_tree[REP_3_6].Freq++;
598 } else if (count <= 10) {
599 s->bl_tree[REPZ_3_10].Freq++;
600 } else {
601 s->bl_tree[REPZ_11_138].Freq++;
602 }
603 count = 0; prevlen = curlen;
604 if (nextlen == 0) {
605 max_count = 138, min_count = 3;
606 } else if (curlen == nextlen) {
607 max_count = 6, min_count = 3;
608 } else {
609 max_count = 7, min_count = 4;
610 }
611 }
612 }
613
614 /* ===========================================
615 * Send a literal or distance tree in compress
616 * bl_tree.
617 */
618 static void send_tree(
619 deflate_state *s,
620 ct_data *tree, /* the tree to be scann
621 int max_code /* and its largest code
622 )
623 {
624 int n; /* iterates ove
625 int prevlen = -1; /* last emitted
626 int curlen; /* length of cu
627 int nextlen = tree[0].Len; /* length of ne
628 int count = 0; /* repeat count
629 int max_count = 7; /* max repeat c
630 int min_count = 4; /* min repeat c
631
632 /* tree[max_code+1].Len = -1; */ /* guard
633 if (nextlen == 0) max_count = 138, min_cou
634
635 for (n = 0; n <= max_code; n++) {
636 curlen = nextlen; nextlen = tree[n+1].
637 if (++count < max_count && curlen == n
638 continue;
639 } else if (count < min_count) {
640 do { send_code(s, curlen, s->bl_tr
641
642 } else if (curlen != 0) {
643 if (curlen != prevlen) {
644 send_code(s, curlen, s->bl_tre
645 }
646 Assert(count >= 3 && count <= 6, "
647 send_code(s, REP_3_6, s->bl_tree);
648
649 } else if (count <= 10) {
650 send_code(s, REPZ_3_10, s->bl_tree
651
652 } else {
653 send_code(s, REPZ_11_138, s->bl_tr
654 }
655 count = 0; prevlen = curlen;
656 if (nextlen == 0) {
657 max_count = 138, min_count = 3;
658 } else if (curlen == nextlen) {
659 max_count = 6, min_count = 3;
660 } else {
661 max_count = 7, min_count = 4;
662 }
663 }
664 }
665
666 /* ===========================================
667 * Construct the Huffman tree for the bit leng
668 * bl_order of the last bit length code to sen
669 */
670 static int build_bl_tree(
671 deflate_state *s
672 )
673 {
674 int max_blindex; /* index of last bit len
675
676 /* Determine the bit length frequencies fo
677 scan_tree(s, (ct_data *)s->dyn_ltree, s->l
678 scan_tree(s, (ct_data *)s->dyn_dtree, s->d
679
680 /* Build the bit length tree: */
681 build_tree(s, (tree_desc *)(&(s->bl_desc))
682 /* opt_len now includes the length of the
683 * the lengths of the bit lengths codes an
684 */
685
686 /* Determine the number of bit length code
687 * requires that at least 4 bit length cod
688 * 3 but the actual value used is 4.)
689 */
690 for (max_blindex = BL_CODES-1; max_blindex
691 if (s->bl_tree[bl_order[max_blindex]].
692 }
693 /* Update opt_len to include the bit lengt
694 s->opt_len += 3*(max_blindex+1) + 5+5+4;
695 Tracev((stderr, "\ndyn trees: dyn %ld, sta
696 s->opt_len, s->static_len));
697
698 return max_blindex;
699 }
700
701 /* ===========================================
702 * Send the header for a block using dynamic H
703 * lengths of the bit length codes, the litera
704 * IN assertion: lcodes >= 257, dcodes >= 1, b
705 */
706 static void send_all_trees(
707 deflate_state *s,
708 int lcodes, /* number of codes for ea
709 int dcodes, /* number of codes for ea
710 int blcodes /* number of codes for ea
711 )
712 {
713 int rank; /* index in b
714
715 Assert (lcodes >= 257 && dcodes >= 1 && bl
716 Assert (lcodes <= L_CODES && dcodes <= D_C
717 "too many codes");
718 Tracev((stderr, "\nbl counts: "));
719 send_bits(s, lcodes-257, 5); /* not +255 a
720 send_bits(s, dcodes-1, 5);
721 send_bits(s, blcodes-4, 4); /* not -3 as
722 for (rank = 0; rank < blcodes; rank++) {
723 Tracev((stderr, "\nbl code %2d ", bl_o
724 send_bits(s, s->bl_tree[bl_order[rank]
725 }
726 Tracev((stderr, "\nbl tree: sent %ld", s->
727
728 send_tree(s, (ct_data *)s->dyn_ltree, lcod
729 Tracev((stderr, "\nlit tree: sent %ld", s-
730
731 send_tree(s, (ct_data *)s->dyn_dtree, dcod
732 Tracev((stderr, "\ndist tree: sent %ld", s
733 }
734
735 /* ===========================================
736 * Send a stored block
737 */
738 void zlib_tr_stored_block(
739 deflate_state *s,
740 char *buf, /* input block */
741 ulg stored_len, /* length of input b
742 int eof /* true if this is t
743 )
744 {
745 send_bits(s, (STORED_BLOCK<<1)+eof, 3); /
746 s->compressed_len = (s->compressed_len + 3
747 s->compressed_len += (stored_len + 4) << 3
748
749 copy_block(s, buf, (unsigned)stored_len, 1
750 }
751
752 /* Send just the `stored block' type code with
753 */
754 void zlib_tr_stored_type_only(
755 deflate_state *s
756 )
757 {
758 send_bits(s, (STORED_BLOCK << 1), 3);
759 bi_windup(s);
760 s->compressed_len = (s->compressed_len + 3
761 }
762
763
764 /* ===========================================
765 * Send one empty static block to give enough
766 * This takes 10 bits, of which 7 may remain i
767 * The current inflate code requires 9 bits of
768 * last two codes for the previous block (real
769 * on 5 bits or less, inflate may have only 5+
770 * the last real code. In this case we send tw
771 * of one. (There are no problems if the previ
772 * To simplify the code, we assume the worst c
773 * on one bit only.
774 */
775 void zlib_tr_align(
776 deflate_state *s
777 )
778 {
779 send_bits(s, STATIC_TREES<<1, 3);
780 send_code(s, END_BLOCK, static_ltree);
781 s->compressed_len += 10L; /* 3 for block t
782 bi_flush(s);
783 /* Of the 10 bits for the empty block, we
784 * (10 - bi_valid) bits. The lookahead for
785 * the EOB of the previous block) was thus
786 * of the EOB plus what we have just sent
787 */
788 if (1 + s->last_eob_len + 10 - s->bi_valid
789 send_bits(s, STATIC_TREES<<1, 3);
790 send_code(s, END_BLOCK, static_ltree);
791 s->compressed_len += 10L;
792 bi_flush(s);
793 }
794 s->last_eob_len = 7;
795 }
796
797 /* ===========================================
798 * Determine the best encoding for the current
799 * trees or store, and output the encoded bloc
800 * returns the total compressed length for the
801 */
802 ulg zlib_tr_flush_block(
803 deflate_state *s,
804 char *buf, /* input block, or N
805 ulg stored_len, /* length of input b
806 int eof /* true if this is t
807 )
808 {
809 ulg opt_lenb, static_lenb; /* opt_len and
810 int max_blindex = 0; /* index of last bit
811
812 /* Build the Huffman trees unless a stored
813 if (s->level > 0) {
814
815 /* Check if the file is ascii or bina
816 if (s->data_type == Z_UNKNOWN) set_dat
817
818 /* Construct the literal and distance
819 build_tree(s, (tree_desc *)(&(s->l_des
820 Tracev((stderr, "\nlit data: dyn %ld,
821 s->static_len));
822
823 build_tree(s, (tree_desc *)(&(s->d_des
824 Tracev((stderr, "\ndist data: dyn %ld,
825 s->static_len));
826 /* At this point, opt_len and static_l
827 * the compressed block data, excludin
828 */
829
830 /* Build the bit length tree for the a
831 * in bl_order of the last bit length
832 */
833 max_blindex = build_bl_tree(s);
834
835 /* Determine the best encoding. Comput
836 opt_lenb = (s->opt_len+3+7)>>3;
837 static_lenb = (s->static_len+3+7)>>3;
838
839 Tracev((stderr, "\nopt %lu(%lu) stat %
840 opt_lenb, s->opt_len, static_l
841 s->last_lit));
842
843 if (static_lenb <= opt_lenb) opt_lenb
844
845 } else {
846 Assert(buf != (char*)0, "lost buf");
847 opt_lenb = static_lenb = stored_len +
848 }
849
850 /* If compression failed and this is the f
851 * and if the .zip file can be seeked (to
852 * the whole file is transformed into a st
853 */
854 #ifdef STORED_FILE_OK
855 # ifdef FORCE_STORED_FILE
856 if (eof && s->compressed_len == 0L) { /* f
857 # else
858 if (stored_len <= opt_lenb && eof && s->co
859 # endif
860 /* Since LIT_BUFSIZE <= 2*WSIZE, the i
861 if (buf == (char*)0) error ("block van
862
863 copy_block(s, buf, (unsigned)stored_le
864 s->compressed_len = stored_len << 3;
865 s->method = STORED;
866 } else
867 #endif /* STORED_FILE_OK */
868
869 #ifdef FORCE_STORED
870 if (buf != (char*)0) { /* force stored blo
871 #else
872 if (stored_len+4 <= opt_lenb && buf != (ch
873 /* 4: two words for the
874 #endif
875 /* The test buf != NULL is only necess
876 * Otherwise we can't have processed m
877 * the last block flush, because compr
878 * successful. If LIT_BUFSIZE <= WSIZE
879 * transform a block into a stored blo
880 */
881 zlib_tr_stored_block(s, buf, stored_le
882
883 #ifdef FORCE_STATIC
884 } else if (static_lenb >= 0) { /* force st
885 #else
886 } else if (static_lenb == opt_lenb) {
887 #endif
888 send_bits(s, (STATIC_TREES<<1)+eof, 3)
889 compress_block(s, (ct_data *)static_lt
890 s->compressed_len += 3 + s->static_len
891 } else {
892 send_bits(s, (DYN_TREES<<1)+eof, 3);
893 send_all_trees(s, s->l_desc.max_code+1
894 max_blindex+1);
895 compress_block(s, (ct_data *)s->dyn_lt
896 s->compressed_len += 3 + s->opt_len;
897 }
898 Assert (s->compressed_len == s->bits_sent,
899 init_block(s);
900
901 if (eof) {
902 bi_windup(s);
903 s->compressed_len += 7; /* align on b
904 }
905 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->
906 s->compressed_len-7*eof));
907
908 return s->compressed_len >> 3;
909 }
910
911 /* ===========================================
912 * Save the match info and tally the frequency
913 * the current block must be flushed.
914 */
915 int zlib_tr_tally(
916 deflate_state *s,
917 unsigned dist, /* distance of matched
918 unsigned lc /* match length-MIN_MA
919 )
920 {
921 s->d_buf[s->last_lit] = (ush)dist;
922 s->l_buf[s->last_lit++] = (uch)lc;
923 if (dist == 0) {
924 /* lc is the unmatched char */
925 s->dyn_ltree[lc].Freq++;
926 } else {
927 s->matches++;
928 /* Here, lc is the match length - MIN_
929 dist--; /* dist = match di
930 Assert((ush)dist < (ush)MAX_DIST(s) &&
931 (ush)lc <= (ush)(MAX_MATCH-MIN_
932 (ush)d_code(dist) < (ush)D_CODE
933
934 s->dyn_ltree[length_code[lc]+LITERALS+
935 s->dyn_dtree[d_code(dist)].Freq++;
936 }
937
938 /* Try to guess if it is profitable to sto
939 if ((s->last_lit & 0xfff) == 0 && s->level
940 /* Compute an upper bound for the comp
941 ulg out_length = (ulg)s->last_lit*8L;
942 ulg in_length = (ulg)((long)s->strstar
943 int dcode;
944 for (dcode = 0; dcode < D_CODES; dcode
945 out_length += (ulg)s->dyn_dtree[dc
946 (5L+extra_dbits[dcode]);
947 }
948 out_length >>= 3;
949 Tracev((stderr,"\nlast_lit %u, in %ld,
950 s->last_lit, in_length, out_len
951 100L - out_length*100L/in_lengt
952 if (s->matches < s->last_lit/2 && out_
953 }
954 return (s->last_lit == s->lit_bufsize-1);
955 /* We avoid equality with lit_bufsize beca
956 * on 16 bit machines and because stored b
957 * 64K-1 bytes.
958 */
959 }
960
961 /* ===========================================
962 * Send the block data compressed using the gi
963 */
964 static void compress_block(
965 deflate_state *s,
966 ct_data *ltree, /* literal tree */
967 ct_data *dtree /* distance tree */
968 )
969 {
970 unsigned dist; /* distance of matched
971 int lc; /* match length or unm
972 unsigned lx = 0; /* running index in l_
973 unsigned code; /* the code to send */
974 int extra; /* number of extra bit
975
976 if (s->last_lit != 0) do {
977 dist = s->d_buf[lx];
978 lc = s->l_buf[lx++];
979 if (dist == 0) {
980 send_code(s, lc, ltree); /* send a
981 Tracecv(isgraph(lc), (stderr," '%c
982 } else {
983 /* Here, lc is the match length -
984 code = length_code[lc];
985 send_code(s, code+LITERALS+1, ltre
986 extra = extra_lbits[code];
987 if (extra != 0) {
988 lc -= base_length[code];
989 send_bits(s, lc, extra);
990 }
991 dist--; /* dist is now the match d
992 code = d_code(dist);
993 Assert (code < D_CODES, "bad d_cod
994
995 send_code(s, code, dtree); /
996 extra = extra_dbits[code];
997 if (extra != 0) {
998 dist -= base_dist[code];
999 send_bits(s, dist, extra); /
1000 }
1001 } /* literal or match pair ? */
1002
1003 /* Check that the overlay between pen
1004 Assert(s->pending < s->lit_bufsize +
1005
1006 } while (lx < s->last_lit);
1007
1008 send_code(s, END_BLOCK, ltree);
1009 s->last_eob_len = ltree[END_BLOCK].Len;
1010 }
1011
1012 /* ==========================================
1013 * Set the data type to ASCII or BINARY, usin
1014 * binary if more than 20% of the bytes are <
1015 * IN assertion: the fields freq of dyn_ltree
1016 * frequencies does not exceed 64K (to fit in
1017 */
1018 static void set_data_type(
1019 deflate_state *s
1020 )
1021 {
1022 int n = 0;
1023 unsigned ascii_freq = 0;
1024 unsigned bin_freq = 0;
1025 while (n < 7) bin_freq += s->dyn_l
1026 while (n < 128) ascii_freq += s->dyn_l
1027 while (n < LITERALS) bin_freq += s->dyn_l
1028 s->data_type = (Byte)(bin_freq > (ascii_f
1029 }
1030
1031 /* ==========================================
1032 * Copy a stored block, storing first the len
1033 * one's complement if requested.
1034 */
1035 static void copy_block(
1036 deflate_state *s,
1037 char *buf, /* the input data *
1038 unsigned len, /* its length */
1039 int header /* true if block he
1040 )
1041 {
1042 bi_windup(s); /* align on byte bou
1043 s->last_eob_len = 8; /* enough lookahead
1044
1045 if (header) {
1046 put_short(s, (ush)len);
1047 put_short(s, (ush)~len);
1048 #ifdef DEBUG_ZLIB
1049 s->bits_sent += 2*16;
1050 #endif
1051 }
1052 #ifdef DEBUG_ZLIB
1053 s->bits_sent += (ulg)len<<3;
1054 #endif
1055 /* bundle up the put_byte(s, *buf++) call
1056 memcpy(&s->pending_buf[s->pending], buf,
1057 s->pending += len;
1058 }
1059
1060
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