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trees.c (44070B)
---
1 /* trees.c -- output deflated data using Huffman coding
2 * Copyright (C) 1995-2005 Jean-loup Gailly
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */
5
6 /*
7 * ALGORITHM
8 *
9 * The "deflation" process uses several Huffman trees. The more
10 * common source values are represented by shorter bit sequences.
11 *
12 * Each code tree is stored in a compressed form which is itself
13 * a Huffman encoding of the lengths of all the code strings (in
14 * ascending order by source values). The actual code strings are
15 * reconstructed from the lengths in the inflate process, as described
16 * in the deflate specification.
17 *
18 * REFERENCES
19 *
20 * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
21 * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
22 *
23 * Storer, James A.
24 * Data Compression: Methods and Theory, pp. 49-50.
25 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
26 *
27 * Sedgewick, R.
28 * Algorithms, p290.
29 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
30 */
31
32 /* @(#) $Id: trees.c 1925 2005-10-06 19:32:02Z baford $ */
33
34 /* #define GEN_TREES_H */
35
36 #include "deflate.h"
37
38 #ifdef DEBUG
39 # include <ctype.h>
40 #endif
41
42 /* ===========================================================================
43 * Constants
44 */
45
46 #define MAX_BL_BITS 7
47 /* Bit length codes must not exceed MAX_BL_BITS bits */
48
49 #define END_BLOCK 256
50 /* end of block literal code */
51
52 #define REP_3_6 16
53 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
54
55 #define REPZ_3_10 17
56 /* repeat a zero length 3-10 times (3 bits of repeat count) */
57
58 #define REPZ_11_138 18
59 /* repeat a zero length 11-138 times (7 bits of repeat count) */
60
61 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
62 = {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};
63
64 local const int extra_dbits[D_CODES] /* extra bits for each distance code */
65 = {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};
66
67 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
68 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
69
70 local const uch bl_order[BL_CODES]
71 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
72 /* The lengths of the bit length codes are sent in order of decreasing
73 * probability, to avoid transmitting the lengths for unused bit length codes.
74 */
75
76 #define Buf_size (8 * 2*sizeof(char))
77 /* Number of bits used within bi_buf. (bi_buf might be implemented on
78 * more than 16 bits on some systems.)
79 */
80
81 /* ===========================================================================
82 * Local data. These are initialized only once.
83 */
84
85 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
86
87 #if defined(GEN_TREES_H) || !defined(STDC)
88 /* non ANSI compilers may not accept trees.h */
89
90 local ct_data static_ltree[L_CODES+2];
91 /* The static literal tree. Since the bit lengths are imposed, there is no
92 * need for the L_CODES extra codes used during heap construction. However
93 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
94 * below).
95 */
96
97 local ct_data static_dtree[D_CODES];
98 /* The static distance tree. (Actually a trivial tree since all codes use
99 * 5 bits.)
100 */
101
102 uch _dist_code[DIST_CODE_LEN];
103 /* Distance codes. The first 256 values correspond to the distances
104 * 3 .. 258, the last 256 values correspond to the top 8 bits of
105 * the 15 bit distances.
106 */
107
108 uch _length_code[MAX_MATCH-MIN_MATCH+1];
109 /* length code for each normalized match length (0 == MIN_MATCH) */
110
111 local int base_length[LENGTH_CODES];
112 /* First normalized length for each code (0 = MIN_MATCH) */
113
114 local int base_dist[D_CODES];
115 /* First normalized distance for each code (0 = distance of 1) */
116
117 #else
118 # include "trees.h"
119 #endif /* GEN_TREES_H */
120
121 struct static_tree_desc_s {
122 const ct_data *static_tree; /* static tree or NULL */
123 const intf *extra_bits; /* extra bits for each code or NULL */
124 int extra_base; /* base index for extra_bits */
125 int elems; /* max number of elements in the tree */
126 int max_length; /* max bit length for the codes */
127 };
128
129 local static_tree_desc static_l_desc =
130 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
131
132 local static_tree_desc static_d_desc =
133 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
134
135 local static_tree_desc static_bl_desc =
136 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
137
138 /* ===========================================================================
139 * Local (static) routines in this file.
140 */
141
142 local void tr_static_init OF((void));
143 local void init_block OF((deflate_state *s));
144 local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
145 local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
146 local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
147 local void build_tree OF((deflate_state *s, tree_desc *desc));
148 local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
149 local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
150 local int build_bl_tree OF((deflate_state *s));
151 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
152 int blcodes));
153 local void compress_block OF((deflate_state *s, ct_data *ltree,
154 ct_data *dtree));
155 local void set_data_type OF((deflate_state *s));
156 local unsigned bi_reverse OF((unsigned value, int length));
157 local void bi_windup OF((deflate_state *s));
158 local void bi_flush OF((deflate_state *s));
159 local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
160 int header));
161
162 #ifdef GEN_TREES_H
163 local void gen_trees_header OF((void));
164 #endif
165
166 #ifndef DEBUG
167 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
168 /* Send a code of the given tree. c and tree must not have side effects */
169
170 #else /* DEBUG */
171 # define send_code(s, c, tree) \
172 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
173 send_bits(s, tree[c].Code, tree[c].Len); }
174 #endif
175
176 /* ===========================================================================
177 * Output a short LSB first on the stream.
178 * IN assertion: there is enough room in pendingBuf.
179 */
180 #define put_short(s, w) { \
181 put_byte(s, (uch)((w) & 0xff)); \
182 put_byte(s, (uch)((ush)(w) >> 8)); \
183 }
184
185 /* ===========================================================================
186 * Send a value on a given number of bits.
187 * IN assertion: length <= 16 and value fits in length bits.
188 */
189 #ifdef DEBUG
190 local void send_bits OF((deflate_state *s, int value, int length));
191
192 local void send_bits(s, value, length)
193 deflate_state *s;
194 int value; /* value to send */
195 int length; /* number of bits */
196 {
197 Tracevv((stderr," l %2d v %4x ", length, value));
198 Assert(length > 0 && length <= 15, "invalid length");
199 s->bits_sent += (ulg)length;
200
201 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
202 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
203 * unused bits in value.
204 */
205 if (s->bi_valid > (int)Buf_size - length) {
206 s->bi_buf |= (value << s->bi_valid);
207 put_short(s, s->bi_buf);
208 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
209 s->bi_valid += length - Buf_size;
210 } else {
211 s->bi_buf |= value << s->bi_valid;
212 s->bi_valid += length;
213 }
214 }
215 #else /* !DEBUG */
216
217 #define send_bits(s, value, length) \
218 { int len = length;\
219 if (s->bi_valid > (int)Buf_size - len) {\
220 int val = value;\
221 s->bi_buf |= (val << s->bi_valid);\
222 put_short(s, s->bi_buf);\
223 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
224 s->bi_valid += len - Buf_size;\
225 } else {\
226 s->bi_buf |= (value) << s->bi_valid;\
227 s->bi_valid += len;\
228 }\
229 }
230 #endif /* DEBUG */
231
232
233 /* the arguments must not have side effects */
234
235 /* ===========================================================================
236 * Initialize the various 'constant' tables.
237 */
238 local void tr_static_init()
239 {
240 #if defined(GEN_TREES_H) || !defined(STDC)
241 static int static_init_done = 0;
242 int n; /* iterates over tree elements */
243 int bits; /* bit counter */
244 int length; /* length value */
245 int code; /* code value */
246 int dist; /* distance index */
247 ush bl_count[MAX_BITS+1];
248 /* number of codes at each bit length for an optimal tree */
249
250 if (static_init_done) return;
251
252 /* For some embedded targets, global variables are not initialized: */
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
259 /* Initialize the mapping length (0..255) -> length code (0..28) */
260 length = 0;
261 for (code = 0; code < LENGTH_CODES-1; code++) {
262 base_length[code] = length;
263 for (n = 0; n < (1<<extra_lbits[code]); n++) {
264 _length_code[length++] = (uch)code;
265 }
266 }
267 Assert (length == 256, "tr_static_init: length != 256");
268 /* Note that the length 255 (match length 258) can be represented
269 * in two different ways: code 284 + 5 bits or code 285, so we
270 * overwrite length_code[255] to use the best encoding:
271 */
272 _length_code[length-1] = (uch)code;
273
274 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
275 dist = 0;
276 for (code = 0 ; code < 16; code++) {
277 base_dist[code] = dist;
278 for (n = 0; n < (1<<extra_dbits[code]); n++) {
279 _dist_code[dist++] = (uch)code;
280 }
281 }
282 Assert (dist == 256, "tr_static_init: dist != 256");
283 dist >>= 7; /* from now on, all distances are divided by 128 */
284 for ( ; code < D_CODES; code++) {
285 base_dist[code] = dist << 7;
286 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
287 _dist_code[256 + dist++] = (uch)code;
288 }
289 }
290 Assert (dist == 256, "tr_static_init: 256+dist != 512");
291
292 /* Construct the codes of the static literal tree */
293 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
294 n = 0;
295 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
296 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
297 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
298 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
299 /* Codes 286 and 287 do not exist, but we must include them in the
300 * tree construction to get a canonical Huffman tree (longest code
301 * all ones)
302 */
303 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
304
305 /* The static distance tree is trivial: */
306 for (n = 0; n < D_CODES; n++) {
307 static_dtree[n].Len = 5;
308 static_dtree[n].Code = bi_reverse((unsigned)n, 5);
309 }
310 static_init_done = 1;
311
312 # ifdef GEN_TREES_H
313 gen_trees_header();
314 # endif
315 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
316 }
317
318 /* ===========================================================================
319 * Genererate the file trees.h describing the static trees.
320 */
321 #ifdef GEN_TREES_H
322 # ifndef DEBUG
323 # include <stdio.h>
324 # endif
325
326 # define SEPARATOR(i, last, width) \
327 ((i) == (last)? "\n};\n\n" : \
328 ((i) % (width) == (width)-1 ? ",\n" : ", "))
329
330 void gen_trees_header()
331 {
332 FILE *header = fopen("trees.h", "w");
333 int i;
334
335 Assert (header != NULL, "Can't open trees.h");
336 fprintf(header,
337 "/* header created automatically with -DGEN_TREES_H */\n\n");
338
339 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
340 for (i = 0; i < L_CODES+2; i++) {
341 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
342 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
343 }
344
345 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
346 for (i = 0; i < D_CODES; i++) {
347 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
348 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
349 }
350
351 fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n");
352 for (i = 0; i < DIST_CODE_LEN; i++) {
353 fprintf(header, "%2u%s", _dist_code[i],
354 SEPARATOR(i, DIST_CODE_LEN-1, 20));
355 }
356
357 fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
358 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
359 fprintf(header, "%2u%s", _length_code[i],
360 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
361 }
362
363 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
364 for (i = 0; i < LENGTH_CODES; i++) {
365 fprintf(header, "%1u%s", base_length[i],
366 SEPARATOR(i, LENGTH_CODES-1, 20));
367 }
368
369 fprintf(header, "local const int base_dist[D_CODES] = {\n");
370 for (i = 0; i < D_CODES; i++) {
371 fprintf(header, "%5u%s", base_dist[i],
372 SEPARATOR(i, D_CODES-1, 10));
373 }
374
375 fclose(header);
376 }
377 #endif /* GEN_TREES_H */
378
379 /* ===========================================================================
380 * Initialize the tree data structures for a new zlib stream.
381 */
382 void _tr_init(s)
383 deflate_state *s;
384 {
385 tr_static_init();
386
387 s->l_desc.dyn_tree = s->dyn_ltree;
388 s->l_desc.stat_desc = &static_l_desc;
389
390 s->d_desc.dyn_tree = s->dyn_dtree;
391 s->d_desc.stat_desc = &static_d_desc;
392
393 s->bl_desc.dyn_tree = s->bl_tree;
394 s->bl_desc.stat_desc = &static_bl_desc;
395
396 s->bi_buf = 0;
397 s->bi_valid = 0;
398 s->last_eob_len = 8; /* enough lookahead for inflate */
399 #ifdef DEBUG
400 s->compressed_len = 0L;
401 s->bits_sent = 0L;
402 #endif
403
404 /* Initialize the first block of the first file: */
405 init_block(s);
406 }
407
408 /* ===========================================================================
409 * Initialize a new block.
410 */
411 local void init_block(s)
412 deflate_state *s;
413 {
414 int n; /* iterates over tree elements */
415
416 /* Initialize the trees. */
417 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
418 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
419 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
420
421 s->dyn_ltree[END_BLOCK].Freq = 1;
422 s->opt_len = s->static_len = 0L;
423 s->last_lit = s->matches = 0;
424 }
425
426 #define SMALLEST 1
427 /* Index within the heap array of least frequent node in the Huffman tree */
428
429
430 /* ===========================================================================
431 * Remove the smallest element from the heap and recreate the heap with
432 * one less element. Updates heap and heap_len.
433 */
434 #define pqremove(s, tree, top) \
435 {\
436 top = s->heap[SMALLEST]; \
437 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
438 pqdownheap(s, tree, SMALLEST); \
439 }
440
441 /* ===========================================================================
442 * Compares to subtrees, using the tree depth as tie breaker when
443 * the subtrees have equal frequency. This minimizes the worst case length.
444 */
445 #define smaller(tree, n, m, depth) \
446 (tree[n].Freq < tree[m].Freq || \
447 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
448
449 /* ===========================================================================
450 * Restore the heap property by moving down the tree starting at node k,
451 * exchanging a node with the smallest of its two sons if necessary, stopping
452 * when the heap property is re-established (each father smaller than its
453 * two sons).
454 */
455 local void pqdownheap(s, tree, k)
456 deflate_state *s;
457 ct_data *tree; /* the tree to restore */
458 int k; /* node to move down */
459 {
460 int v = s->heap[k];
461 int j = k << 1; /* left son of k */
462 while (j <= s->heap_len) {
463 /* Set j to the smallest of the two sons: */
464 if (j < s->heap_len &&
465 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
466 j++;
467 }
468 /* Exit if v is smaller than both sons */
469 if (smaller(tree, v, s->heap[j], s->depth)) break;
470
471 /* Exchange v with the smallest son */
472 s->heap[k] = s->heap[j]; k = j;
473
474 /* And continue down the tree, setting j to the left son of k */
475 j <<= 1;
476 }
477 s->heap[k] = v;
478 }
479
480 /* ===========================================================================
481 * Compute the optimal bit lengths for a tree and update the total bit length
482 * for the current block.
483 * IN assertion: the fields freq and dad are set, heap[heap_max] and
484 * above are the tree nodes sorted by increasing frequency.
485 * OUT assertions: the field len is set to the optimal bit length, the
486 * array bl_count contains the frequencies for each bit length.
487 * The length opt_len is updated; static_len is also updated if stree is
488 * not null.
489 */
490 local void gen_bitlen(s, desc)
491 deflate_state *s;
492 tree_desc *desc; /* the tree descriptor */
493 {
494 ct_data *tree = desc->dyn_tree;
495 int max_code = desc->max_code;
496 const ct_data *stree = desc->stat_desc->static_tree;
497 const intf *extra = desc->stat_desc->extra_bits;
498 int base = desc->stat_desc->extra_base;
499 int max_length = desc->stat_desc->max_length;
500 int h; /* heap index */
501 int n, m; /* iterate over the tree elements */
502 int bits; /* bit length */
503 int xbits; /* extra bits */
504 ush f; /* frequency */
505 int overflow = 0; /* number of elements with bit length too large */
506
507 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
508
509 /* In a first pass, compute the optimal bit lengths (which may
510 * overflow in the case of the bit length tree).
511 */
512 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
513
514 for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
515 n = s->heap[h];
516 bits = tree[tree[n].Dad].Len + 1;
517 if (bits > max_length) bits = max_length, overflow++;
518 tree[n].Len = (ush)bits;
519 /* We overwrite tree[n].Dad which is no longer needed */
520
521 if (n > max_code) continue; /* not a leaf node */
522
523 s->bl_count[bits]++;
524 xbits = 0;
525 if (n >= base) xbits = extra[n-base];
526 f = tree[n].Freq;
527 s->opt_len += (ulg)f * (bits + xbits);
528 if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
529 }
530 if (overflow == 0) return;
531
532 Trace((stderr,"\nbit length overflow\n"));
533 /* This happens for example on obj2 and pic of the Calgary corpus */
534
535 /* Find the first bit length which could increase: */
536 do {
537 bits = max_length-1;
538 while (s->bl_count[bits] == 0) bits--;
539 s->bl_count[bits]--; /* move one leaf down the tree */
540 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
541 s->bl_count[max_length]--;
542 /* The brother of the overflow item also moves one step up,
543 * but this does not affect bl_count[max_length]
544 */
545 overflow -= 2;
546 } while (overflow > 0);
547
548 /* Now recompute all bit lengths, scanning in increasing frequency.
549 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
550 * lengths instead of fixing only the wrong ones. This idea is taken
551 * from 'ar' written by Haruhiko Okumura.)
552 */
553 for (bits = max_length; bits != 0; bits--) {
554 n = s->bl_count[bits];
555 while (n != 0) {
556 m = s->heap[--h];
557 if (m > max_code) continue;
558 if ((unsigned) tree[m].Len != (unsigned) bits) {
559 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
560 s->opt_len += ((long)bits - (long)tree[m].Len)
561 *(long)tree[m].Freq;
562 tree[m].Len = (ush)bits;
563 }
564 n--;
565 }
566 }
567 }
568
569 /* ===========================================================================
570 * Generate the codes for a given tree and bit counts (which need not be
571 * optimal).
572 * IN assertion: the array bl_count contains the bit length statistics for
573 * the given tree and the field len is set for all tree elements.
574 * OUT assertion: the field code is set for all tree elements of non
575 * zero code length.
576 */
577 local void gen_codes (tree, max_code, bl_count)
578 ct_data *tree; /* the tree to decorate */
579 int max_code; /* largest code with non zero frequency */
580 ushf *bl_count; /* number of codes at each bit length */
581 {
582 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
583 ush code = 0; /* running code value */
584 int bits; /* bit index */
585 int n; /* code index */
586
587 /* The distribution counts are first used to generate the code values
588 * without bit reversal.
589 */
590 for (bits = 1; bits <= MAX_BITS; bits++) {
591 next_code[bits] = code = (code + bl_count[bits-1]) << 1;
592 }
593 /* Check that the bit counts in bl_count are consistent. The last code
594 * must be all ones.
595 */
596 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
597 "inconsistent bit counts");
598 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
599
600 for (n = 0; n <= max_code; n++) {
601 int len = tree[n].Len;
602 if (len == 0) continue;
603 /* Now reverse the bits */
604 tree[n].Code = bi_reverse(next_code[len]++, len);
605
606 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
607 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
608 }
609 }
610
611 /* ===========================================================================
612 * Construct one Huffman tree and assigns the code bit strings and lengths.
613 * Update the total bit length for the current block.
614 * IN assertion: the field freq is set for all tree elements.
615 * OUT assertions: the fields len and code are set to the optimal bit length
616 * and corresponding code. The length opt_len is updated; static_len is
617 * also updated if stree is not null. The field max_code is set.
618 */
619 local void build_tree(s, desc)
620 deflate_state *s;
621 tree_desc *desc; /* the tree descriptor */
622 {
623 ct_data *tree = desc->dyn_tree;
624 const ct_data *stree = desc->stat_desc->static_tree;
625 int elems = desc->stat_desc->elems;
626 int n, m; /* iterate over heap elements */
627 int max_code = -1; /* largest code with non zero frequency */
628 int node; /* new node being created */
629
630 /* Construct the initial heap, with least frequent element in
631 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
632 * heap[0] is not used.
633 */
634 s->heap_len = 0, s->heap_max = HEAP_SIZE;
635
636 for (n = 0; n < elems; n++) {
637 if (tree[n].Freq != 0) {
638 s->heap[++(s->heap_len)] = max_code = n;
639 s->depth[n] = 0;
640 } else {
641 tree[n].Len = 0;
642 }
643 }
644
645 /* The pkzip format requires that at least one distance code exists,
646 * and that at least one bit should be sent even if there is only one
647 * possible code. So to avoid special checks later on we force at least
648 * two codes of non zero frequency.
649 */
650 while (s->heap_len < 2) {
651 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
652 tree[node].Freq = 1;
653 s->depth[node] = 0;
654 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
655 /* node is 0 or 1 so it does not have extra bits */
656 }
657 desc->max_code = max_code;
658
659 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
660 * establish sub-heaps of increasing lengths:
661 */
662 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
663
664 /* Construct the Huffman tree by repeatedly combining the least two
665 * frequent nodes.
666 */
667 node = elems; /* next internal node of the tree */
668 do {
669 pqremove(s, tree, n); /* n = node of least frequency */
670 m = s->heap[SMALLEST]; /* m = node of next least frequency */
671
672 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
673 s->heap[--(s->heap_max)] = m;
674
675 /* Create a new node father of n and m */
676 tree[node].Freq = tree[n].Freq + tree[m].Freq;
677 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
678 s->depth[n] : s->depth[m]) + 1);
679 tree[n].Dad = tree[m].Dad = (ush)node;
680 #ifdef DUMP_BL_TREE
681 if (tree == s->bl_tree) {
682 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
683 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
684 }
685 #endif
686 /* and insert the new node in the heap */
687 s->heap[SMALLEST] = node++;
688 pqdownheap(s, tree, SMALLEST);
689
690 } while (s->heap_len >= 2);
691
692 s->heap[--(s->heap_max)] = s->heap[SMALLEST];
693
694 /* At this point, the fields freq and dad are set. We can now
695 * generate the bit lengths.
696 */
697 gen_bitlen(s, (tree_desc *)desc);
698
699 /* The field len is now set, we can generate the bit codes */
700 gen_codes ((ct_data *)tree, max_code, s->bl_count);
701 }
702
703 /* ===========================================================================
704 * Scan a literal or distance tree to determine the frequencies of the codes
705 * in the bit length tree.
706 */
707 local void scan_tree (s, tree, max_code)
708 deflate_state *s;
709 ct_data *tree; /* the tree to be scanned */
710 int max_code; /* and its largest code of non zero frequency */
711 {
712 int n; /* iterates over all tree elements */
713 int prevlen = -1; /* last emitted length */
714 int curlen; /* length of current code */
715 int nextlen = tree[0].Len; /* length of next code */
716 int count = 0; /* repeat count of the current code */
717 int max_count = 7; /* max repeat count */
718 int min_count = 4; /* min repeat count */
719
720 if (nextlen == 0) max_count = 138, min_count = 3;
721 tree[max_code+1].Len = (ush)0xffff; /* guard */
722
723 for (n = 0; n <= max_code; n++) {
724 curlen = nextlen; nextlen = tree[n+1].Len;
725 if (++count < max_count && curlen == nextlen) {
726 continue;
727 } else if (count < min_count) {
728 s->bl_tree[curlen].Freq += count;
729 } else if (curlen != 0) {
730 if (curlen != prevlen) s->bl_tree[curlen].Freq++;
731 s->bl_tree[REP_3_6].Freq++;
732 } else if (count <= 10) {
733 s->bl_tree[REPZ_3_10].Freq++;
734 } else {
735 s->bl_tree[REPZ_11_138].Freq++;
736 }
737 count = 0; prevlen = curlen;
738 if (nextlen == 0) {
739 max_count = 138, min_count = 3;
740 } else if (curlen == nextlen) {
741 max_count = 6, min_count = 3;
742 } else {
743 max_count = 7, min_count = 4;
744 }
745 }
746 }
747
748 /* ===========================================================================
749 * Send a literal or distance tree in compressed form, using the codes in
750 * bl_tree.
751 */
752 local void send_tree (s, tree, max_code)
753 deflate_state *s;
754 ct_data *tree; /* the tree to be scanned */
755 int max_code; /* and its largest code of non zero frequency */
756 {
757 int n; /* iterates over all tree elements */
758 int prevlen = -1; /* last emitted length */
759 int curlen; /* length of current code */
760 int nextlen = tree[0].Len; /* length of next code */
761 int count = 0; /* repeat count of the current code */
762 int max_count = 7; /* max repeat count */
763 int min_count = 4; /* min repeat count */
764
765 /* tree[max_code+1].Len = -1; */ /* guard already set */
766 if (nextlen == 0) max_count = 138, min_count = 3;
767
768 for (n = 0; n <= max_code; n++) {
769 curlen = nextlen; nextlen = tree[n+1].Len;
770 if (++count < max_count && curlen == nextlen) {
771 continue;
772 } else if (count < min_count) {
773 do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
774
775 } else if (curlen != 0) {
776 if (curlen != prevlen) {
777 send_code(s, curlen, s->bl_tree); count--;
778 }
779 Assert(count >= 3 && count <= 6, " 3_6?");
780 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
781
782 } else if (count <= 10) {
783 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
784
785 } else {
786 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
787 }
788 count = 0; prevlen = curlen;
789 if (nextlen == 0) {
790 max_count = 138, min_count = 3;
791 } else if (curlen == nextlen) {
792 max_count = 6, min_count = 3;
793 } else {
794 max_count = 7, min_count = 4;
795 }
796 }
797 }
798
799 /* ===========================================================================
800 * Construct the Huffman tree for the bit lengths and return the index in
801 * bl_order of the last bit length code to send.
802 */
803 local int build_bl_tree(s)
804 deflate_state *s;
805 {
806 int max_blindex; /* index of last bit length code of non zero freq */
807
808 /* Determine the bit length frequencies for literal and distance trees */
809 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
810 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
811
812 /* Build the bit length tree: */
813 build_tree(s, (tree_desc *)(&(s->bl_desc)));
814 /* opt_len now includes the length of the tree representations, except
815 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
816 */
817
818 /* Determine the number of bit length codes to send. The pkzip format
819 * requires that at least 4 bit length codes be sent. (appnote.txt says
820 * 3 but the actual value used is 4.)
821 */
822 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
823 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
824 }
825 /* Update opt_len to include the bit length tree and counts */
826 s->opt_len += 3*(max_blindex+1) + 5+5+4;
827 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
828 s->opt_len, s->static_len));
829
830 return max_blindex;
831 }
832
833 /* ===========================================================================
834 * Send the header for a block using dynamic Huffman trees: the counts, the
835 * lengths of the bit length codes, the literal tree and the distance tree.
836 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
837 */
838 local void send_all_trees(s, lcodes, dcodes, blcodes)
839 deflate_state *s;
840 int lcodes, dcodes, blcodes; /* number of codes for each tree */
841 {
842 int rank; /* index in bl_order */
843
844 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
845 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
846 "too many codes");
847 Tracev((stderr, "\nbl counts: "));
848 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
849 send_bits(s, dcodes-1, 5);
850 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
851 for (rank = 0; rank < blcodes; rank++) {
852 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
853 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
854 }
855 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
856
857 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
858 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
859
860 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
861 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
862 }
863
864 /* ===========================================================================
865 * Send a stored block
866 */
867 void _tr_stored_block(s, buf, stored_len, eof)
868 deflate_state *s;
869 charf *buf; /* input block */
870 ulg stored_len; /* length of input block */
871 int eof; /* true if this is the last block for a file */
872 {
873 send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */
874 #ifdef DEBUG
875 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
876 s->compressed_len += (stored_len + 4) << 3;
877 #endif
878 copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
879 }
880
881 /* ===========================================================================
882 * Send one empty static block to give enough lookahead for inflate.
883 * This takes 10 bits, of which 7 may remain in the bit buffer.
884 * The current inflate code requires 9 bits of lookahead. If the
885 * last two codes for the previous block (real code plus EOB) were coded
886 * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
887 * the last real code. In this case we send two empty static blocks instead
888 * of one. (There are no problems if the previous block is stored or fixed.)
889 * To simplify the code, we assume the worst case of last real code encoded
890 * on one bit only.
891 */
892 void _tr_align(s)
893 deflate_state *s;
894 {
895 send_bits(s, STATIC_TREES<<1, 3);
896 send_code(s, END_BLOCK, static_ltree);
897 #ifdef DEBUG
898 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
899 #endif
900 bi_flush(s);
901 /* Of the 10 bits for the empty block, we have already sent
902 * (10 - bi_valid) bits. The lookahead for the last real code (before
903 * the EOB of the previous block) was thus at least one plus the length
904 * of the EOB plus what we have just sent of the empty static block.
905 */
906 if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
907 send_bits(s, STATIC_TREES<<1, 3);
908 send_code(s, END_BLOCK, static_ltree);
909 #ifdef DEBUG
910 s->compressed_len += 10L;
911 #endif
912 bi_flush(s);
913 }
914 s->last_eob_len = 7;
915 }
916
917 /* ===========================================================================
918 * Determine the best encoding for the current block: dynamic trees, static
919 * trees or store, and output the encoded block to the zip file.
920 */
921 void _tr_flush_block(s, buf, stored_len, eof)
922 deflate_state *s;
923 charf *buf; /* input block, or NULL if too old */
924 ulg stored_len; /* length of input block */
925 int eof; /* true if this is the last block for a file */
926 {
927 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
928 int max_blindex = 0; /* index of last bit length code of non zero freq */
929
930 /* Build the Huffman trees unless a stored block is forced */
931 if (s->level > 0) {
932
933 /* Check if the file is binary or text */
934 if (stored_len > 0 && s->strm->data_type == Z_UNKNOWN)
935 set_data_type(s);
936
937 /* Construct the literal and distance trees */
938 build_tree(s, (tree_desc *)(&(s->l_desc)));
939 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
940 s->static_len));
941
942 build_tree(s, (tree_desc *)(&(s->d_desc)));
943 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
944 s->static_len));
945 /* At this point, opt_len and static_len are the total bit lengths of
946 * the compressed block data, excluding the tree representations.
947 */
948
949 /* Build the bit length tree for the above two trees, and get the index
950 * in bl_order of the last bit length code to send.
951 */
952 max_blindex = build_bl_tree(s);
953
954 /* Determine the best encoding. Compute the block lengths in bytes. */
955 opt_lenb = (s->opt_len+3+7)>>3;
956 static_lenb = (s->static_len+3+7)>>3;
957
958 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
959 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
960 s->last_lit));
961
962 if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
963
964 } else {
965 Assert(buf != (char*)0, "lost buf");
966 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
967 }
968
969 #ifdef FORCE_STORED
970 if (buf != (char*)0) { /* force stored block */
971 #else
972 if (stored_len+4 <= opt_lenb && buf != (char*)0) {
973 /* 4: two words for the lengths */
974 #endif
975 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
976 * Otherwise we can't have processed more than WSIZE input bytes since
977 * the last block flush, because compression would have been
978 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
979 * transform a block into a stored block.
980 */
981 _tr_stored_block(s, buf, stored_len, eof);
982
983 #ifdef FORCE_STATIC
984 } else if (static_lenb >= 0) { /* force static trees */
985 #else
986 } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
987 #endif
988 send_bits(s, (STATIC_TREES<<1)+eof, 3);
989 compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
990 #ifdef DEBUG
991 s->compressed_len += 3 + s->static_len;
992 #endif
993 } else {
994 send_bits(s, (DYN_TREES<<1)+eof, 3);
995 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
996 max_blindex+1);
997 compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
998 #ifdef DEBUG
999 s->compressed_len += 3 + s->opt_len;
1000 #endif
1001 }
1002 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1003 /* The above check is made mod 2^32, for files larger than 512 MB
1004 * and uLong implemented on 32 bits.
1005 */
1006 init_block(s);
1007
1008 if (eof) {
1009 bi_windup(s);
1010 #ifdef DEBUG
1011 s->compressed_len += 7; /* align on byte boundary */
1012 #endif
1013 }
1014 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1015 s->compressed_len-7*eof));
1016 }
1017
1018 /* ===========================================================================
1019 * Save the match info and tally the frequency counts. Return true if
1020 * the current block must be flushed.
1021 */
1022 int _tr_tally (s, dist, lc)
1023 deflate_state *s;
1024 unsigned dist; /* distance of matched string */
1025 unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1026 {
1027 s->d_buf[s->last_lit] = (ush)dist;
1028 s->l_buf[s->last_lit++] = (uch)lc;
1029 if (dist == 0) {
1030 /* lc is the unmatched char */
1031 s->dyn_ltree[lc].Freq++;
1032 } else {
1033 s->matches++;
1034 /* Here, lc is the match length - MIN_MATCH */
1035 dist--; /* dist = match distance - 1 */
1036 Assert((ush)dist < (ush)MAX_DIST(s) &&
1037 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1038 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1039
1040 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1041 s->dyn_dtree[d_code(dist)].Freq++;
1042 }
1043
1044 #ifdef TRUNCATE_BLOCK
1045 /* Try to guess if it is profitable to stop the current block here */
1046 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1047 /* Compute an upper bound for the compressed length */
1048 ulg out_length = (ulg)s->last_lit*8L;
1049 ulg in_length = (ulg)((long)s->strstart - s->block_start);
1050 int dcode;
1051 for (dcode = 0; dcode < D_CODES; dcode++) {
1052 out_length += (ulg)s->dyn_dtree[dcode].Freq *
1053 (5L+extra_dbits[dcode]);
1054 }
1055 out_length >>= 3;
1056 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1057 s->last_lit, in_length, out_length,
1058 100L - out_length*100L/in_length));
1059 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1060 }
1061 #endif
1062 return (s->last_lit == s->lit_bufsize-1);
1063 /* We avoid equality with lit_bufsize because of wraparound at 64K
1064 * on 16 bit machines and because stored blocks are restricted to
1065 * 64K-1 bytes.
1066 */
1067 }
1068
1069 /* ===========================================================================
1070 * Send the block data compressed using the given Huffman trees
1071 */
1072 local void compress_block(s, ltree, dtree)
1073 deflate_state *s;
1074 ct_data *ltree; /* literal tree */
1075 ct_data *dtree; /* distance tree */
1076 {
1077 unsigned dist; /* distance of matched string */
1078 int lc; /* match length or unmatched char (if dist == 0) */
1079 unsigned lx = 0; /* running index in l_buf */
1080 unsigned code; /* the code to send */
1081 int extra; /* number of extra bits to send */
1082
1083 if (s->last_lit != 0) do {
1084 dist = s->d_buf[lx];
1085 lc = s->l_buf[lx++];
1086 if (dist == 0) {
1087 send_code(s, lc, ltree); /* send a literal byte */
1088 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1089 } else {
1090 /* Here, lc is the match length - MIN_MATCH */
1091 code = _length_code[lc];
1092 send_code(s, code+LITERALS+1, ltree); /* send the length code */
1093 extra = extra_lbits[code];
1094 if (extra != 0) {
1095 lc -= base_length[code];
1096 send_bits(s, lc, extra); /* send the extra length bits */
1097 }
1098 dist--; /* dist is now the match distance - 1 */
1099 code = d_code(dist);
1100 Assert (code < D_CODES, "bad d_code");
1101
1102 send_code(s, code, dtree); /* send the distance code */
1103 extra = extra_dbits[code];
1104 if (extra != 0) {
1105 dist -= base_dist[code];
1106 send_bits(s, dist, extra); /* send the extra distance bits */
1107 }
1108 } /* literal or match pair ? */
1109
1110 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1111 Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1112 "pendingBuf overflow");
1113
1114 } while (lx < s->last_lit);
1115
1116 send_code(s, END_BLOCK, ltree);
1117 s->last_eob_len = ltree[END_BLOCK].Len;
1118 }
1119
1120 /* ===========================================================================
1121 * Set the data type to BINARY or TEXT, using a crude approximation:
1122 * set it to Z_TEXT if all symbols are either printable characters (33 to 255)
1123 * or white spaces (9 to 13, or 32); or set it to Z_BINARY otherwise.
1124 * IN assertion: the fields Freq of dyn_ltree are set.
1125 */
1126 local void set_data_type(s)
1127 deflate_state *s;
1128 {
1129 int n;
1130
1131 for (n = 0; n < 9; n++)
1132 if (s->dyn_ltree[n].Freq != 0)
1133 break;
1134 if (n == 9)
1135 for (n = 14; n < 32; n++)
1136 if (s->dyn_ltree[n].Freq != 0)
1137 break;
1138 s->strm->data_type = (n == 32) ? Z_TEXT : Z_BINARY;
1139 }
1140
1141 /* ===========================================================================
1142 * Reverse the first len bits of a code, using straightforward code (a faster
1143 * method would use a table)
1144 * IN assertion: 1 <= len <= 15
1145 */
1146 local unsigned bi_reverse(code, len)
1147 unsigned code; /* the value to invert */
1148 int len; /* its bit length */
1149 {
1150 register unsigned res = 0;
1151 do {
1152 res |= code & 1;
1153 code >>= 1, res <<= 1;
1154 } while (--len > 0);
1155 return res >> 1;
1156 }
1157
1158 /* ===========================================================================
1159 * Flush the bit buffer, keeping at most 7 bits in it.
1160 */
1161 local void bi_flush(s)
1162 deflate_state *s;
1163 {
1164 if (s->bi_valid == 16) {
1165 put_short(s, s->bi_buf);
1166 s->bi_buf = 0;
1167 s->bi_valid = 0;
1168 } else if (s->bi_valid >= 8) {
1169 put_byte(s, (Byte)s->bi_buf);
1170 s->bi_buf >>= 8;
1171 s->bi_valid -= 8;
1172 }
1173 }
1174
1175 /* ===========================================================================
1176 * Flush the bit buffer and align the output on a byte boundary
1177 */
1178 local void bi_windup(s)
1179 deflate_state *s;
1180 {
1181 if (s->bi_valid > 8) {
1182 put_short(s, s->bi_buf);
1183 } else if (s->bi_valid > 0) {
1184 put_byte(s, (Byte)s->bi_buf);
1185 }
1186 s->bi_buf = 0;
1187 s->bi_valid = 0;
1188 #ifdef DEBUG
1189 s->bits_sent = (s->bits_sent+7) & ~7;
1190 #endif
1191 }
1192
1193 /* ===========================================================================
1194 * Copy a stored block, storing first the length and its
1195 * one's complement if requested.
1196 */
1197 local void copy_block(s, buf, len, header)
1198 deflate_state *s;
1199 charf *buf; /* the input data */
1200 unsigned len; /* its length */
1201 int header; /* true if block header must be written */
1202 {
1203 bi_windup(s); /* align on byte boundary */
1204 s->last_eob_len = 8; /* enough lookahead for inflate */
1205
1206 if (header) {
1207 put_short(s, (ush)len);
1208 put_short(s, (ush)~len);
1209 #ifdef DEBUG
1210 s->bits_sent += 2*16;
1211 #endif
1212 }
1213 #ifdef DEBUG
1214 s->bits_sent += (ulg)len<<3;
1215 #endif
1216 while (len--) {
1217 put_byte(s, *buf++);
1218 }
1219 }