1 /* trees.c -- output deflated data using Huffman coding
2 * Copyright (C) 1995-2012 Jean-loup Gailly
3 * detect_data_type() function provided freely by Cosmin Truta, 2006
4 * For conditions of distribution and use, see copyright notice in zlib.h
5 */
6
7 /*
8 * ALGORITHM
9 *
10 * The "deflation" process uses several Huffman trees. The more
11 * common source values are represented by shorter bit sequences.
12 *
13 * Each code tree is stored in a compressed form which is itself
14 * a Huffman encoding of the lengths of all the code strings (in
15 * ascending order by source values). The actual code strings are
16 * reconstructed from the lengths in the inflate process, as described
17 * in the deflate specification.
18 *
19 * REFERENCES
20 *
21 * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
22 * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
23 *
24 * Storer, James A.
25 * Data Compression: Methods and Theory, pp. 49-50.
26 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
27 *
28 * Sedgewick, R.
29 * Algorithms, p290.
30 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
31 */
32
33 /* @(#) $Id$ */
34
35 /* #define GEN_TREES_H */
36
37 #include "deflate.h"
38
39 #ifdef DEBUG
40 # include <ctype.h>
41 #endif
42
43 /* ===========================================================================
44 * Constants
45 */
46
47 #define MAX_BL_BITS 7
48 /* Bit length codes must not exceed MAX_BL_BITS bits */
49
50 #define END_BLOCK 256
51 /* end of block literal code */
52
53 #define REP_3_6 16
54 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
55
56 #define REPZ_3_10 17
57 /* repeat a zero length 3-10 times (3 bits of repeat count) */
58
59 #define REPZ_11_138 18
60 /* repeat a zero length 11-138 times (7 bits of repeat count) */
61
62 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
63 = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};
64
65 local const int extra_dbits[D_CODES] /* extra bits for each distance code */
66 = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
67
68 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
69 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
70
71 local const uch bl_order[BL_CODES]
72 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
73 /* The lengths of the bit length codes are sent in order of decreasing
74 * probability, to avoid transmitting the lengths for unused bit length codes.
75 */
76
77 /* ===========================================================================
78 * Local data. These are initialized only once.
79 */
80
81 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
82
83 #if defined(GEN_TREES_H) || !defined(STDC)
84 /* non ANSI compilers may not accept trees.h */
85
86 local ct_data static_ltree[L_CODES+2];
87 /* The static literal tree. Since the bit lengths are imposed, there is no
88 * need for the L_CODES extra codes used during heap construction. However
89 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
90 * below).
91 */
92
93 local ct_data static_dtree[D_CODES];
94 /* The static distance tree. (Actually a trivial tree since all codes use
95 * 5 bits.)
96 */
97
98 uch _dist_code[DIST_CODE_LEN];
99 /* Distance codes. The first 256 values correspond to the distances
100 * 3 .. 258, the last 256 values correspond to the top 8 bits of
101 * the 15 bit distances.
102 */
103
104 uch _length_code[MAX_MATCH-MIN_MATCH+1];
105 /* length code for each normalized match length (0 == MIN_MATCH) */
106
107 local int base_length[LENGTH_CODES];
108 /* First normalized length for each code (0 = MIN_MATCH) */
109
110 local int base_dist[D_CODES];
111 /* First normalized distance for each code (0 = distance of 1) */
112
113 #else
114 # include "trees.h"
115 #endif /* GEN_TREES_H */
116
117 struct static_tree_desc_s {
118 const ct_data *static_tree; /* static tree or NULL */
119 const intf *extra_bits; /* extra bits for each code or NULL */
120 int extra_base; /* base index for extra_bits */
121 int elems; /* max number of elements in the tree */
122 int max_length; /* max bit length for the codes */
123 };
124
125 local static_tree_desc static_l_desc =
126 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
127
128 local static_tree_desc static_d_desc =
129 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
130
131 local static_tree_desc static_bl_desc =
132 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
133
134 /* ===========================================================================
135 * Local (static) routines in this file.
136 */
137
138 local void tr_static_init OF((void));
139 local void init_block OF((deflate_state *s));
140 local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
141 local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
142 local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
143 local void build_tree OF((deflate_state *s, tree_desc *desc));
144 local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
145 local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
146 local int build_bl_tree OF((deflate_state *s));
147 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
148 int blcodes));
149 local void compress_block OF((deflate_state *s, const ct_data *ltree,
150 const ct_data *dtree));
151 local int detect_data_type OF((deflate_state *s));
152 local unsigned bi_reverse OF((unsigned value, int length));
153 local void bi_windup OF((deflate_state *s));
154 local void bi_flush OF((deflate_state *s));
155 local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
156 int header));
157
158 #ifdef GEN_TREES_H
159 local void gen_trees_header OF((void));
160 #endif
161
162 #ifndef DEBUG
163 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
164 /* Send a code of the given tree. c and tree must not have side effects */
165
166 #else /* DEBUG */
167 # define send_code(s, c, tree) \
168 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
169 send_bits(s, tree[c].Code, tree[c].Len); }
170 #endif
171
172 /* ===========================================================================
173 * Output a short LSB first on the stream.
174 * IN assertion: there is enough room in pendingBuf.
175 */
176 #define put_short(s, w) { \
177 put_byte(s, (uch)((w) & 0xff)); \
178 put_byte(s, (uch)((ush)(w) >> 8)); \
179 }
180
181 /* ===========================================================================
182 * Send a value on a given number of bits.
183 * IN assertion: length <= 16 and value fits in length bits.
184 */
185 #ifdef DEBUG
186 local void send_bits OF((deflate_state *s, int value, int length));
187
188 local void send_bits(s, value, length)
189 deflate_state *s;
190 int value; /* value to send */
191 int length; /* number of bits */
192 {
193 Tracevv((stderr," l %2d v %4x ", length, value));
194 Assert(length > 0 && length <= 15, "invalid length");
195 s->bits_sent += (ulg)length;
196
197 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
198 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
199 * unused bits in value.
200 */
201 if (s->bi_valid > (int)Buf_size - length) {
202 s->bi_buf |= (ush)value << s->bi_valid;
203 put_short(s, s->bi_buf);
204 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
205 s->bi_valid += length - Buf_size;
206 } else {
207 s->bi_buf |= (ush)value << s->bi_valid;
208 s->bi_valid += length;
209 }
210 }
211 #else /* !DEBUG */
212
213 #define send_bits(s, value, length) \
214 { int len = length;\
215 if (s->bi_valid > (int)Buf_size - len) {\
216 int val = value;\
217 s->bi_buf |= (ush)val << s->bi_valid;\
218 put_short(s, s->bi_buf);\
219 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
220 s->bi_valid += len - Buf_size;\
221 } else {\
222 s->bi_buf |= (ush)(value) << s->bi_valid;\
223 s->bi_valid += len;\
224 }\
225 }
226 #endif /* DEBUG */
227
228
229 /* the arguments must not have side effects */
230
231 /* ===========================================================================
232 * Initialize the various 'constant' tables.
233 */
234 local void tr_static_init()
235 {
236 #if defined(GEN_TREES_H) || !defined(STDC)
237 static int static_init_done = 0;
238 int n; /* iterates over tree elements */
239 int bits; /* bit counter */
240 int length; /* length value */
241 int code; /* code value */
242 int dist; /* distance index */
243 ush bl_count[MAX_BITS+1];
244 /* number of codes at each bit length for an optimal tree */
245
246 if (static_init_done) return;
247
248 /* For some embedded targets, global variables are not initialized: */
249 #ifdef NO_INIT_GLOBAL_POINTERS
250 static_l_desc.static_tree = static_ltree;
251 static_l_desc.extra_bits = extra_lbits;
252 static_d_desc.static_tree = static_dtree;
253 static_d_desc.extra_bits = extra_dbits;
254 static_bl_desc.extra_bits = extra_blbits;
255 #endif
256
257 /* Initialize the mapping length (0..255) -> length code (0..28) */
258 length = 0;
259 for (code = 0; code < LENGTH_CODES-1; code++) {
260 base_length[code] = length;
261 for (n = 0; n < (1<<extra_lbits[code]); n++) {
262 _length_code[length++] = (uch)code;
263 }
264 }
265 Assert (length == 256, "tr_static_init: length != 256");
266 /* Note that the length 255 (match length 258) can be represented
267 * in two different ways: code 284 + 5 bits or code 285, so we
268 * overwrite length_code[255] to use the best encoding:
269 */
270 _length_code[length-1] = (uch)code;
271
272 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
273 dist = 0;
274 for (code = 0 ; code < 16; code++) {
275 base_dist[code] = dist;
276 for (n = 0; n < (1<<extra_dbits[code]); n++) {
277 _dist_code[dist++] = (uch)code;
278 }
279 }
280 Assert (dist == 256, "tr_static_init: dist != 256");
281 dist >>= 7; /* from now on, all distances are divided by 128 */
282 for ( ; code < D_CODES; code++) {
283 base_dist[code] = dist << 7;
284 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
285 _dist_code[256 + dist++] = (uch)code;
286 }
287 }
288 Assert (dist == 256, "tr_static_init: 256+dist != 512");
289
290 /* Construct the codes of the static literal tree */
291 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
292 n = 0;
293 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
294 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
295 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
296 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
297 /* Codes 286 and 287 do not exist, but we must include them in the
298 * tree construction to get a canonical Huffman tree (longest code
299 * all ones)
300 */
301 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
302
303 /* The static distance tree is trivial: */
304 for (n = 0; n < D_CODES; n++) {
305 static_dtree[n].Len = 5;
306 static_dtree[n].Code = bi_reverse((unsigned)n, 5);
307 }
308 static_init_done = 1;
309
310 # ifdef GEN_TREES_H
311 gen_trees_header();
312 # endif
313 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
314 }
315
316 /* ===========================================================================
317 * Genererate the file trees.h describing the static trees.
318 */
319 #ifdef GEN_TREES_H
320 # ifndef DEBUG
321 # include <stdio.h>
322 # endif
323
324 # define SEPARATOR(i, last, width) \
325 ((i) == (last)? "\n};\n\n" : \
326 ((i) % (width) == (width)-1 ? ",\n" : ", "))
327
328 void gen_trees_header()
329 {
330 FILE *header = fopen("trees.h", "w");
331 int i;
332
333 Assert (header != NULL, "Can't open trees.h");
334 fprintf(header,
335 "/* header created automatically with -DGEN_TREES_H */\n\n");
336
337 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
338 for (i = 0; i < L_CODES+2; i++) {
339 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
340 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
341 }
342
343 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
344 for (i = 0; i < D_CODES; i++) {
345 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
346 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
347 }
348
349 fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
350 for (i = 0; i < DIST_CODE_LEN; i++) {
351 fprintf(header, "%2u%s", _dist_code[i],
352 SEPARATOR(i, DIST_CODE_LEN-1, 20));
353 }
354
355 fprintf(header,
356 "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
357 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
358 fprintf(header, "%2u%s", _length_code[i],
359 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
360 }
361
362 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
363 for (i = 0; i < LENGTH_CODES; i++) {
364 fprintf(header, "%1u%s", base_length[i],
365 SEPARATOR(i, LENGTH_CODES-1, 20));
366 }
367
368 fprintf(header, "local const int base_dist[D_CODES] = {\n");
369 for (i = 0; i < D_CODES; i++) {
370 fprintf(header, "%5u%s", base_dist[i],
371 SEPARATOR(i, D_CODES-1, 10));
372 }
373
374 fclose(header);
375 }
376 #endif /* GEN_TREES_H */
377
378 /* ===========================================================================
379 * Initialize the tree data structures for a new zlib stream.
380 */
381 void ZLIB_INTERNAL _tr_init(s)
382 deflate_state *s;
383 {
384 tr_static_init();
385
386 s->l_desc.dyn_tree = s->dyn_ltree;
387 s->l_desc.stat_desc = &static_l_desc;
388
389 s->d_desc.dyn_tree = s->dyn_dtree;
390 s->d_desc.stat_desc = &static_d_desc;
391
392 s->bl_desc.dyn_tree = s->bl_tree;
393 s->bl_desc.stat_desc = &static_bl_desc;
394
395 s->bi_buf = 0;
396 s->bi_valid = 0;
397 #ifdef DEBUG
398 s->compressed_len = 0L;
399 s->bits_sent = 0L;
400 #endif
401
402 /* Initialize the first block of the first file: */
403 init_block(s);
404 }
405
406 /* ===========================================================================
407 * Initialize a new block.
408 */
409 local void init_block(s)
410 deflate_state *s;
411 {
412 int n; /* iterates over tree elements */
413
414 /* Initialize the trees. */
415 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
416 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
417 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
418
419 s->dyn_ltree[END_BLOCK].Freq = 1;
420 s->opt_len = s->static_len = 0L;
421 s->last_lit = s->matches = 0;
422 }
423
424 #define SMALLEST 1
425 /* Index within the heap array of least frequent node in the Huffman tree */
426
427
428 /* ===========================================================================
429 * Remove the smallest element from the heap and recreate the heap with
430 * one less element. Updates heap and heap_len.
431 */
432 #define pqremove(s, tree, top) \
433 {\
434 top = s->heap[SMALLEST]; \
435 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
436 pqdownheap(s, tree, SMALLEST); \
437 }
438
439 /* ===========================================================================
440 * Compares to subtrees, using the tree depth as tie breaker when
441 * the subtrees have equal frequency. This minimizes the worst case length.
442 */
443 #define smaller(tree, n, m, depth) \
444 (tree[n].Freq < tree[m].Freq || \
445 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
446
447 /* ===========================================================================
448 * Restore the heap property by moving down the tree starting at node k,
449 * exchanging a node with the smallest of its two sons if necessary, stopping
450 * when the heap property is re-established (each father smaller than its
451 * two sons).
452 */
453 local void pqdownheap(s, tree, k)
454 deflate_state *s;
455 ct_data *tree; /* the tree to restore */
456 int k; /* node to move down */
457 {
458 int v = s->heap[k];
459 int j = k << 1; /* left son of k */
460 while (j <= s->heap_len) {
461 /* Set j to the smallest of the two sons: */
462 if (j < s->heap_len &&
463 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
464 j++;
465 }
466 /* Exit if v is smaller than both sons */
467 if (smaller(tree, v, s->heap[j], s->depth)) break;
468
469 /* Exchange v with the smallest son */
470 s->heap[k] = s->heap[j]; k = j;
471
472 /* And continue down the tree, setting j to the left son of k */
473 j <<= 1;
474 }
475 s->heap[k] = v;
476 }
477
478 /* ===========================================================================
479 * Compute the optimal bit lengths for a tree and update the total bit length
480 * for the current block.
481 * IN assertion: the fields freq and dad are set, heap[heap_max] and
482 * above are the tree nodes sorted by increasing frequency.
483 * OUT assertions: the field len is set to the optimal bit length, the
484 * array bl_count contains the frequencies for each bit length.
485 * The length opt_len is updated; static_len is also updated if stree is
486 * not null.
487 */
488 local void gen_bitlen(s, desc)
489 deflate_state *s;
490 tree_desc *desc; /* the tree descriptor */
491 {
492 ct_data *tree = desc->dyn_tree;
493 int max_code = desc->max_code;
494 const ct_data *stree = desc->stat_desc->static_tree;
495 const intf *extra = desc->stat_desc->extra_bits;
496 int base = desc->stat_desc->extra_base;
497 int max_length = desc->stat_desc->max_length;
498 int h; /* heap index */
499 int n, m; /* iterate over the tree elements */
500 int bits; /* bit length */
501 int xbits; /* extra bits */
502 ush f; /* frequency */
503 int overflow = 0; /* number of elements with bit length too large */
504
505 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
506
507 /* In a first pass, compute the optimal bit lengths (which may
508 * overflow in the case of the bit length tree).
509 */
510 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
511
512 for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
513 n = s->heap[h];
514 bits = tree[tree[n].Dad].Len + 1;
515 if (bits > max_length) bits = max_length, overflow++;
516 tree[n].Len = (ush)bits;
517 /* We overwrite tree[n].Dad which is no longer needed */
518
519 if (n > max_code) continue; /* not a leaf node */
520
521 s->bl_count[bits]++;
522 xbits = 0;
523 if (n >= base) xbits = extra[n-base];
524 f = tree[n].Freq;
525 s->opt_len += (ulg)f * (bits + xbits);
526 if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
527 }
528 if (overflow == 0) return;
529
530 Trace((stderr,"\nbit length overflow\n"));
531 /* This happens for example on obj2 and pic of the Calgary corpus */
532
533 /* Find the first bit length which could increase: */
534 do {
535 bits = max_length-1;
536 while (s->bl_count[bits] == 0) bits--;
537 s->bl_count[bits]--; /* move one leaf down the tree */
538 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
539 s->bl_count[max_length]--;
540 /* The brother of the overflow item also moves one step up,
541 * but this does not affect bl_count[max_length]
542 */
543 overflow -= 2;
544 } while (overflow > 0);
545
546 /* Now recompute all bit lengths, scanning in increasing frequency.
547 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
548 * lengths instead of fixing only the wrong ones. This idea is taken
549 * from 'ar' written by Haruhiko Okumura.)
550 */
551 for (bits = max_length; bits != 0; bits--) {
552 n = s->bl_count[bits];
553 while (n != 0) {
554 m = s->heap[--h];
555 if (m > max_code) continue;
556 if ((unsigned) tree[m].Len != (unsigned) bits) {
557 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
558 s->opt_len += ((long)bits - (long)tree[m].Len)
559 *(long)tree[m].Freq;
560 tree[m].Len = (ush)bits;
561 }
562 n--;
563 }
564 }
565 }
566
567 /* ===========================================================================
568 * Generate the codes for a given tree and bit counts (which need not be
569 * optimal).
570 * IN assertion: the array bl_count contains the bit length statistics for
571 * the given tree and the field len is set for all tree elements.
572 * OUT assertion: the field code is set for all tree elements of non
573 * zero code length.
574 */
575 local void gen_codes (tree, max_code, bl_count)
576 ct_data *tree; /* the tree to decorate */
577 int max_code; /* largest code with non zero frequency */
578 ushf *bl_count; /* number of codes at each bit length */
579 {
580 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
581 ush code = 0; /* running code value */
582 int bits; /* bit index */
583 int n; /* code index */
584
585 /* The distribution counts are first used to generate the code values
586 * without bit reversal.
587 */
588 for (bits = 1; bits <= MAX_BITS; bits++) {
589 next_code[bits] = code = (code + bl_count[bits-1]) << 1;
590 }
591 /* Check that the bit counts in bl_count are consistent. The last code
592 * must be all ones.
593 */
594 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
595 "inconsistent bit counts");
596 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
597
598 for (n = 0; n <= max_code; n++) {
599 int len = tree[n].Len;
600 if (len == 0) continue;
601 /* Now reverse the bits */
602 tree[n].Code = bi_reverse(next_code[len]++, len);
603
604 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
605 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
606 }
607 }
608
609 /* ===========================================================================
610 * Construct one Huffman tree and assigns the code bit strings and lengths.
611 * Update the total bit length for the current block.
612 * IN assertion: the field freq is set for all tree elements.
613 * OUT assertions: the fields len and code are set to the optimal bit length
614 * and corresponding code. The length opt_len is updated; static_len is
615 * also updated if stree is not null. The field max_code is set.
616 */
617 local void build_tree(s, desc)
618 deflate_state *s;
619 tree_desc *desc; /* the tree descriptor */
620 {
621 ct_data *tree = desc->dyn_tree;
622 const ct_data *stree = desc->stat_desc->static_tree;
623 int elems = desc->stat_desc->elems;
624 int n, m; /* iterate over heap elements */
625 int max_code = -1; /* largest code with non zero frequency */
626 int node; /* new node being created */
627
628 /* Construct the initial heap, with least frequent element in
629 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
630 * heap[0] is not used.
631 */
632 s->heap_len = 0, s->heap_max = HEAP_SIZE;
633
634 for (n = 0; n < elems; n++) {
635 if (tree[n].Freq != 0) {
636 s->heap[++(s->heap_len)] = max_code = n;
637 s->depth[n] = 0;
638 } else {
639 tree[n].Len = 0;
640 }
641 }
642
643 /* The pkzip format requires that at least one distance code exists,
644 * and that at least one bit should be sent even if there is only one
645 * possible code. So to avoid special checks later on we force at least
646 * two codes of non zero frequency.
647 */
648 while (s->heap_len < 2) {
649 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
650 tree[node].Freq = 1;
651 s->depth[node] = 0;
652 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
653 /* node is 0 or 1 so it does not have extra bits */
654 }
655 desc->max_code = max_code;
656
657 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
658 * establish sub-heaps of increasing lengths:
659 */
660 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
661
662 /* Construct the Huffman tree by repeatedly combining the least two
663 * frequent nodes.
664 */
665 node = elems; /* next internal node of the tree */
666 do {
667 pqremove(s, tree, n); /* n = node of least frequency */
668 m = s->heap[SMALLEST]; /* m = node of next least frequency */
669
670 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
671 s->heap[--(s->heap_max)] = m;
672
673 /* Create a new node father of n and m */
674 tree[node].Freq = tree[n].Freq + tree[m].Freq;
675 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
676 s->depth[n] : s->depth[m]) + 1);
677 tree[n].Dad = tree[m].Dad = (ush)node;
678 #ifdef DUMP_BL_TREE
679 if (tree == s->bl_tree) {
680 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
681 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
682 }
683 #endif
684 /* and insert the new node in the heap */
685 s->heap[SMALLEST] = node++;
686 pqdownheap(s, tree, SMALLEST);
687
688 } while (s->heap_len >= 2);
689
690 s->heap[--(s->heap_max)] = s->heap[SMALLEST];
691
692 /* At this point, the fields freq and dad are set. We can now
693 * generate the bit lengths.
694 */
695 gen_bitlen(s, (tree_desc *)desc);
696
697 /* The field len is now set, we can generate the bit codes */
698 gen_codes ((ct_data *)tree, max_code, s->bl_count);
699 }
700
701 /* ===========================================================================
702 * Scan a literal or distance tree to determine the frequencies of the codes
703 * in the bit length tree.
704 */
705 local void scan_tree (s, tree, max_code)
706 deflate_state *s;
707 ct_data *tree; /* the tree to be scanned */
708 int max_code; /* and its largest code of non zero frequency */
709 {
710 int n; /* iterates over all tree elements */
711 int prevlen = -1; /* last emitted length */
712 int curlen; /* length of current code */
713 int nextlen = tree[0].Len; /* length of next code */
714 int count = 0; /* repeat count of the current code */
715 int max_count = 7; /* max repeat count */
716 int min_count = 4; /* min repeat count */
717
718 if (nextlen == 0) max_count = 138, min_count = 3;
719 tree[max_code+1].Len = (ush)0xffff; /* guard */
720
721 for (n = 0; n <= max_code; n++) {
722 curlen = nextlen; nextlen = tree[n+1].Len;
723 if (++count < max_count && curlen == nextlen) {
724 continue;
725 } else if (count < min_count) {
726 s->bl_tree[curlen].Freq += count;
727 } else if (curlen != 0) {
728 if (curlen != prevlen) s->bl_tree[curlen].Freq++;
729 s->bl_tree[REP_3_6].Freq++;
730 } else if (count <= 10) {
731 s->bl_tree[REPZ_3_10].Freq++;
732 } else {
733 s->bl_tree[REPZ_11_138].Freq++;
734 }
735 count = 0; prevlen = curlen;
736 if (nextlen == 0) {
737 max_count = 138, min_count = 3;
738 } else if (curlen == nextlen) {
739 max_count = 6, min_count = 3;
740 } else {
741 max_count = 7, min_count = 4;
742 }
743 }
744 }
745
746 /* ===========================================================================
747 * Send a literal or distance tree in compressed form, using the codes in
748 * bl_tree.
749 */
750 local void send_tree (s, tree, max_code)
751 deflate_state *s;
752 ct_data *tree; /* the tree to be scanned */
753 int max_code; /* and its largest code of non zero frequency */
754 {
755 int n; /* iterates over all tree elements */
756 int prevlen = -1; /* last emitted length */
757 int curlen; /* length of current code */
758 int nextlen = tree[0].Len; /* length of next code */
759 int count = 0; /* repeat count of the current code */
760 int max_count = 7; /* max repeat count */
761 int min_count = 4; /* min repeat count */
762
763 /* tree[max_code+1].Len = -1; */ /* guard already set */
764 if (nextlen == 0) max_count = 138, min_count = 3;
765
766 for (n = 0; n <= max_code; n++) {
767 curlen = nextlen; nextlen = tree[n+1].Len;
768 if (++count < max_count && curlen == nextlen) {
769 continue;
770 } else if (count < min_count) {
771 do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
772
773 } else if (curlen != 0) {
774 if (curlen != prevlen) {
775 send_code(s, curlen, s->bl_tree); count--;
776 }
777 Assert(count >= 3 && count <= 6, " 3_6?");
778 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
779
780 } else if (count <= 10) {
781 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
782
783 } else {
784 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
785 }
786 count = 0; prevlen = curlen;
787 if (nextlen == 0) {
788 max_count = 138, min_count = 3;
789 } else if (curlen == nextlen) {
790 max_count = 6, min_count = 3;
791 } else {
792 max_count = 7, min_count = 4;
793 }
794 }
795 }
796
797 /* ===========================================================================
798 * Construct the Huffman tree for the bit lengths and return the index in
799 * bl_order of the last bit length code to send.
800 */
801 local int build_bl_tree(s)
802 deflate_state *s;
803 {
804 int max_blindex; /* index of last bit length code of non zero freq */
805
806 /* Determine the bit length frequencies for literal and distance trees */
807 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
808 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
809
810 /* Build the bit length tree: */
811 build_tree(s, (tree_desc *)(&(s->bl_desc)));
812 /* opt_len now includes the length of the tree representations, except
813 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
814 */
815
816 /* Determine the number of bit length codes to send. The pkzip format
817 * requires that at least 4 bit length codes be sent. (appnote.txt says
818 * 3 but the actual value used is 4.)
819 */
820 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
821 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
822 }
823 /* Update opt_len to include the bit length tree and counts */
824 s->opt_len += 3*(max_blindex+1) + 5+5+4;
825 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
826 s->opt_len, s->static_len));
827
828 return max_blindex;
829 }
830
831 /* ===========================================================================
832 * Send the header for a block using dynamic Huffman trees: the counts, the
833 * lengths of the bit length codes, the literal tree and the distance tree.
834 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
835 */
836 local void send_all_trees(s, lcodes, dcodes, blcodes)
837 deflate_state *s;
838 int lcodes, dcodes, blcodes; /* number of codes for each tree */
839 {
840 int rank; /* index in bl_order */
841
842 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
843 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
844 "too many codes");
845 Tracev((stderr, "\nbl counts: "));
846 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
847 send_bits(s, dcodes-1, 5);
848 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
849 for (rank = 0; rank < blcodes; rank++) {
850 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
851 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
852 }
853 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
854
855 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
856 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
857
858 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
859 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
860 }
861
862 /* ===========================================================================
863 * Send a stored block
864 */
865 void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
866 deflate_state *s;
867 charf *buf; /* input block */
868 ulg stored_len; /* length of input block */
869 int last; /* one if this is the last block for a file */
870 {
871 send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */
872 #ifdef DEBUG
873 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
874 s->compressed_len += (stored_len + 4) << 3;
875 #endif
876 copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
877 }
878
879 /* ===========================================================================
880 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
881 */
882 void ZLIB_INTERNAL _tr_flush_bits(s)
883 deflate_state *s;
884 {
885 bi_flush(s);
886 }
887
888 /* ===========================================================================
889 * Send one empty static block to give enough lookahead for inflate.
890 * This takes 10 bits, of which 7 may remain in the bit buffer.
891 */
892 void ZLIB_INTERNAL _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 }
902
903 /* ===========================================================================
904 * Determine the best encoding for the current block: dynamic trees, static
905 * trees or store, and output the encoded block to the zip file.
906 */
907 void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
908 deflate_state *s;
909 charf *buf; /* input block, or NULL if too old */
910 ulg stored_len; /* length of input block */
911 int last; /* one if this is the last block for a file */
912 {
913 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
914 int max_blindex = 0; /* index of last bit length code of non zero freq */
915
916 /* Build the Huffman trees unless a stored block is forced */
917 if (s->level > 0) {
918
919 /* Check if the file is binary or text */
920 if (s->strm->data_type == Z_UNKNOWN)
921 s->strm->data_type = detect_data_type(s);
922
923 /* Construct the literal and distance trees */
924 build_tree(s, (tree_desc *)(&(s->l_desc)));
925 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
926 s->static_len));
927
928 build_tree(s, (tree_desc *)(&(s->d_desc)));
929 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
930 s->static_len));
931 /* At this point, opt_len and static_len are the total bit lengths of
932 * the compressed block data, excluding the tree representations.
933 */
934
935 /* Build the bit length tree for the above two trees, and get the index
936 * in bl_order of the last bit length code to send.
937 */
938 max_blindex = build_bl_tree(s);
939
940 /* Determine the best encoding. Compute the block lengths in bytes. */
941 opt_lenb = (s->opt_len+3+7)>>3;
942 static_lenb = (s->static_len+3+7)>>3;
943
944 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
945 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
946 s->last_lit));
947
948 if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
949
950 } else {
951 Assert(buf != (char*)0, "lost buf");
952 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
953 }
954
955 #ifdef FORCE_STORED
956 if (buf != (char*)0) { /* force stored block */
957 #else
958 if (stored_len+4 <= opt_lenb && buf != (char*)0) {
959 /* 4: two words for the lengths */
960 #endif
961 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
962 * Otherwise we can't have processed more than WSIZE input bytes since
963 * the last block flush, because compression would have been
964 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
965 * transform a block into a stored block.
966 */
967 _tr_stored_block(s, buf, stored_len, last);
968
969 #ifdef FORCE_STATIC
970 } else if (static_lenb >= 0) { /* force static trees */
971 #else
972 } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
973 #endif
974 send_bits(s, (STATIC_TREES<<1)+last, 3);
975 compress_block(s, (const ct_data *)static_ltree,
976 (const ct_data *)static_dtree);
977 #ifdef DEBUG
978 s->compressed_len += 3 + s->static_len;
979 #endif
980 } else {
981 send_bits(s, (DYN_TREES<<1)+last, 3);
982 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
983 max_blindex+1);
984 compress_block(s, (const ct_data *)s->dyn_ltree,
985 (const ct_data *)s->dyn_dtree);
986 #ifdef DEBUG
987 s->compressed_len += 3 + s->opt_len;
988 #endif
989 }
990 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
991 /* The above check is made mod 2^32, for files larger than 512 MB
992 * and uLong implemented on 32 bits.
993 */
994 init_block(s);
995
996 if (last) {
997 bi_windup(s);
998 #ifdef DEBUG
999 s->compressed_len += 7; /* align on byte boundary */
1000 #endif
1001 }
1002 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1003 s->compressed_len-7*last));
1004 }
1005
1006 /* ===========================================================================
1007 * Save the match info and tally the frequency counts. Return true if
1008 * the current block must be flushed.
1009 */
1010 int ZLIB_INTERNAL _tr_tally (s, dist, lc)
1011 deflate_state *s;
1012 unsigned dist; /* distance of matched string */
1013 unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1014 {
1015 s->d_buf[s->last_lit] = (ush)dist;
1016 s->l_buf[s->last_lit++] = (uch)lc;
1017 if (dist == 0) {
1018 /* lc is the unmatched char */
1019 s->dyn_ltree[lc].Freq++;
1020 } else {
1021 s->matches++;
1022 /* Here, lc is the match length - MIN_MATCH */
1023 dist--; /* dist = match distance - 1 */
1024 Assert((ush)dist < (ush)MAX_DIST(s) &&
1025 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1026 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1027
1028 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1029 s->dyn_dtree[d_code(dist)].Freq++;
1030 }
1031
1032 #ifdef TRUNCATE_BLOCK
1033 /* Try to guess if it is profitable to stop the current block here */
1034 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1035 /* Compute an upper bound for the compressed length */
1036 ulg out_length = (ulg)s->last_lit*8L;
1037 ulg in_length = (ulg)((long)s->strstart - s->block_start);
1038 int dcode;
1039 for (dcode = 0; dcode < D_CODES; dcode++) {
1040 out_length += (ulg)s->dyn_dtree[dcode].Freq *
1041 (5L+extra_dbits[dcode]);
1042 }
1043 out_length >>= 3;
1044 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1045 s->last_lit, in_length, out_length,
1046 100L - out_length*100L/in_length));
1047 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1048 }
1049 #endif
1050 return (s->last_lit == s->lit_bufsize-1);
1051 /* We avoid equality with lit_bufsize because of wraparound at 64K
1052 * on 16 bit machines and because stored blocks are restricted to
1053 * 64K-1 bytes.
1054 */
1055 }
1056
1057 /* ===========================================================================
1058 * Send the block data compressed using the given Huffman trees
1059 */
1060 local void compress_block(s, ltree, dtree)
1061 deflate_state *s;
1062 const ct_data *ltree; /* literal tree */
1063 const ct_data *dtree; /* distance tree */
1064 {
1065 unsigned dist; /* distance of matched string */
1066 int lc; /* match length or unmatched char (if dist == 0) */
1067 unsigned lx = 0; /* running index in l_buf */
1068 unsigned code; /* the code to send */
1069 int extra; /* number of extra bits to send */
1070
1071 if (s->last_lit != 0) do {
1072 dist = s->d_buf[lx];
1073 lc = s->l_buf[lx++];
1074 if (dist == 0) {
1075 send_code(s, lc, ltree); /* send a literal byte */
1076 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1077 } else {
1078 /* Here, lc is the match length - MIN_MATCH */
1079 code = _length_code[lc];
1080 send_code(s, code+LITERALS+1, ltree); /* send the length code */
1081 extra = extra_lbits[code];
1082 if (extra != 0) {
1083 lc -= base_length[code];
1084 send_bits(s, lc, extra); /* send the extra length bits */
1085 }
1086 dist--; /* dist is now the match distance - 1 */
1087 code = d_code(dist);
1088 Assert (code < D_CODES, "bad d_code");
1089
1090 send_code(s, code, dtree); /* send the distance code */
1091 extra = extra_dbits[code];
1092 if (extra != 0) {
1093 dist -= base_dist[code];
1094 send_bits(s, dist, extra); /* send the extra distance bits */
1095 }
1096 } /* literal or match pair ? */
1097
1098 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1099 Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1100 "pendingBuf overflow");
1101
1102 } while (lx < s->last_lit);
1103
1104 send_code(s, END_BLOCK, ltree);
1105 }
1106
1107 /* ===========================================================================
1108 * Check if the data type is TEXT or BINARY, using the following algorithm:
1109 * - TEXT if the two conditions below are satisfied:
1110 * a) There are no non-portable control characters belonging to the
1111 * "black list" (0..6, 14..25, 28..31).
1112 * b) There is at least one printable character belonging to the
1113 * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1114 * - BINARY otherwise.
1115 * - The following partially-portable control characters form a
1116 * "gray list" that is ignored in this detection algorithm:
1117 * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1118 * IN assertion: the fields Freq of dyn_ltree are set.
1119 */
1120 local int detect_data_type(s)
1121 deflate_state *s;
1122 {
1123 /* black_mask is the bit mask of black-listed bytes
1124 * set bits 0..6, 14..25, and 28..31
1125 * 0xf3ffc07f = binary 11110011111111111100000001111111
1126 */
1127 unsigned long black_mask = 0xf3ffc07fUL;
1128 int n;
1129
1130 /* Check for non-textual ("black-listed") bytes. */
1131 for (n = 0; n <= 31; n++, black_mask >>= 1)
1132 if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1133 return Z_BINARY;
1134
1135 /* Check for textual ("white-listed") bytes. */
1136 if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1137 || s->dyn_ltree[13].Freq != 0)
1138 return Z_TEXT;
1139 for (n = 32; n < LITERALS; n++)
1140 if (s->dyn_ltree[n].Freq != 0)
1141 return Z_TEXT;
1142
1143 /* There are no "black-listed" or "white-listed" bytes:
1144 * this stream either is empty or has tolerated ("gray-listed") bytes only.
1145 */
1146 return Z_BINARY;
1147 }
1148
1149 /* ===========================================================================
1150 * Reverse the first len bits of a code, using straightforward code (a faster
1151 * method would use a table)
1152 * IN assertion: 1 <= len <= 15
1153 */
1154 local unsigned bi_reverse(code, len)
1155 unsigned code; /* the value to invert */
1156 int len; /* its bit length */
1157 {
1158 register unsigned res = 0;
1159 do {
1160 res |= code & 1;
1161 code >>= 1, res <<= 1;
1162 } while (--len > 0);
1163 return res >> 1;
1164 }
1165
1166 /* ===========================================================================
1167 * Flush the bit buffer, keeping at most 7 bits in it.
1168 */
1169 local void bi_flush(s)
1170 deflate_state *s;
1171 {
1172 if (s->bi_valid == 16) {
1173 put_short(s, s->bi_buf);
1174 s->bi_buf = 0;
1175 s->bi_valid = 0;
1176 } else if (s->bi_valid >= 8) {
1177 put_byte(s, (Byte)s->bi_buf);
1178 s->bi_buf >>= 8;
1179 s->bi_valid -= 8;
1180 }
1181 }
1182
1183 /* ===========================================================================
1184 * Flush the bit buffer and align the output on a byte boundary
1185 */
1186 local void bi_windup(s)
1187 deflate_state *s;
1188 {
1189 if (s->bi_valid > 8) {
1190 put_short(s, s->bi_buf);
1191 } else if (s->bi_valid > 0) {
1192 put_byte(s, (Byte)s->bi_buf);
1193 }
1194 s->bi_buf = 0;
1195 s->bi_valid = 0;
1196 #ifdef DEBUG
1197 s->bits_sent = (s->bits_sent+7) & ~7;
1198 #endif
1199 }
1200
1201 /* ===========================================================================
1202 * Copy a stored block, storing first the length and its
1203 * one's complement if requested.
1204 */
1205 local void copy_block(s, buf, len, header)
1206 deflate_state *s;
1207 charf *buf; /* the input data */
1208 unsigned len; /* its length */
1209 int header; /* true if block header must be written */
1210 {
1211 bi_windup(s); /* align on byte boundary */
1212
1213 if (header) {
1214 put_short(s, (ush)len);
1215 put_short(s, (ush)~len);
1216 #ifdef DEBUG
1217 s->bits_sent += 2*16;
1218 #endif
1219 }
1220 #ifdef DEBUG
1221 s->bits_sent += (ulg)len<<3;
1222 #endif
1223 while (len--) {
1224 put_byte(s, *buf++);
1225 }
1226 }