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1 /* trees.c -- output deflated data using Huffman coding
2 * Copyright (C) 1995-1998 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 /* @(#) $Id$ */
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 #define MAX(a,b) (a >= b ? a : b)
234 /* the arguments must not have side effects */
235
236 /* ===========================================================================
237 * Initialize the various 'constant' tables.
238 */
239 local void tr_static_init()
240 {
241 #if defined(GEN_TREES_H) || !defined(STDC)
242 static int static_init_done = 0;
243 int n; /* iterates over tree elements */
244 int bits; /* bit counter */
245 int length; /* length value */
246 int code; /* code value */
247 int dist; /* distance index */
248 ush bl_count[MAX_BITS+1];
249 /* number of codes at each bit length for an optimal tree */
250
251 if (static_init_done) return;
252
253 /* For some embedded targets, global variables are not initialized: */
254 static_l_desc.static_tree = static_ltree;
255 static_l_desc.extra_bits = extra_lbits;
256 static_d_desc.static_tree = static_dtree;
257 static_d_desc.extra_bits = extra_dbits;
258 static_bl_desc.extra_bits = extra_blbits;
259
260 /* Initialize the mapping length (0..255) -> length code (0..28) */
261 length = 0;
262 for (code = 0; code < LENGTH_CODES-1; code++) {
263 base_length[code] = length;
264 for (n = 0; n < (1<<extra_lbits[code]); n++) {
265 _length_code[length++] = (uch)code;
266 }
267 }
268 Assert (length == 256, "tr_static_init: length != 256");
269 /* Note that the length 255 (match length 258) can be represented
270 * in two different ways: code 284 + 5 bits or code 285, so we
271 * overwrite length_code[255] to use the best encoding:
272 */
273 _length_code[length-1] = (uch)code;
274
275 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
276 dist = 0;
277 for (code = 0 ; code < 16; code++) {
278 base_dist[code] = dist;
279 for (n = 0; n < (1<<extra_dbits[code]); n++) {
280 _dist_code[dist++] = (uch)code;
281 }
282 }
283 Assert (dist == 256, "tr_static_init: dist != 256");
284 dist >>= 7; /* from now on, all distances are divided by 128 */
285 for ( ; code < D_CODES; code++) {
286 base_dist[code] = dist << 7;
287 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
288 _dist_code[256 + dist++] = (uch)code;
289 }
290 }
291 Assert (dist == 256, "tr_static_init: 256+dist != 512");
292
293 /* Construct the codes of the static literal tree */
294 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
295 n = 0;
296 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
297 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
298 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
299 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
300 /* Codes 286 and 287 do not exist, but we must include them in the
301 * tree construction to get a canonical Huffman tree (longest code
302 * all ones)
303 */
304 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
305
306 /* The static distance tree is trivial: */
307 for (n = 0; n < D_CODES; n++) {
308 static_dtree[n].Len = 5;
309 static_dtree[n].Code = bi_reverse((unsigned)n, 5);
310 }
311 static_init_done = 1;
312
313 # ifdef GEN_TREES_H
314 gen_trees_header();
315 # endif
316 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
317 }
318
319 /* ===========================================================================
320 * Genererate the file trees.h describing the static trees.
321 */
322 #ifdef GEN_TREES_H
323 # ifndef DEBUG
324 # include <stdio.h>
325 # endif
326
327 # define SEPARATOR(i, last, width) \
328 ((i) == (last)? "\n};\n\n" : \
329 ((i) % (width) == (width)-1 ? ",\n" : ", "))
330
331 void gen_trees_header()
332 {
333 FILE *header = fopen("trees.h", "w");
334 int i;
335
336 Assert (header != NULL, "Can't open trees.h");
337 fprintf(header,
338 "/* header created automatically with -DGEN_TREES_H */\n\n");
339
340 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
341 for (i = 0; i < L_CODES+2; i++) {
342 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
343 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
344 }
345
346 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
347 for (i = 0; i < D_CODES; i++) {
348 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
349 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
350 }
351
352 fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n");
353 for (i = 0; i < DIST_CODE_LEN; i++) {
354 fprintf(header, "%2u%s", _dist_code[i],
355 SEPARATOR(i, DIST_CODE_LEN-1, 20));
356 }
357
358 fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
359 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
360 fprintf(header, "%2u%s", _length_code[i],
361 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
362 }
363
364 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
365 for (i = 0; i < LENGTH_CODES; i++) {
366 fprintf(header, "%1u%s", base_length[i],
367 SEPARATOR(i, LENGTH_CODES-1, 20));
368 }
369
370 fprintf(header, "local const int base_dist[D_CODES] = {\n");
371 for (i = 0; i < D_CODES; i++) {
372 fprintf(header, "%5u%s", base_dist[i],
373 SEPARATOR(i, D_CODES-1, 10));
374 }
375
376 fclose(header);
377 }
378 #endif /* GEN_TREES_H */
379
380 /* ===========================================================================
381 * Initialize the tree data structures for a new zlib stream.
382 */
383 void _tr_init(s)
384 deflate_state *s;
385 {
386 tr_static_init();
387
388 s->l_desc.dyn_tree = s->dyn_ltree;
389 s->l_desc.stat_desc = &static_l_desc;
390
391 s->d_desc.dyn_tree = s->dyn_dtree;
392 s->d_desc.stat_desc = &static_d_desc;
393
394 s->bl_desc.dyn_tree = s->bl_tree;
395 s->bl_desc.stat_desc = &static_bl_desc;
396
397 s->bi_buf = 0;
398 s->bi_valid = 0;
399 s->last_eob_len = 8; /* enough lookahead for inflate */
400 #ifdef DEBUG
401 s->compressed_len = 0L;
402 s->bits_sent = 0L;
403 #endif
404
405 /* Initialize the first block of the first file: */
406 init_block(s);
407 }
408
409 /* ===========================================================================
410 * Initialize a new block.
411 */
412 local void init_block(s)
413 deflate_state *s;
414 {
415 int n; /* iterates over tree elements */
416
417 /* Initialize the trees. */
418 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
419 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
420 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
421
422 s->dyn_ltree[END_BLOCK].Freq = 1;
423 s->opt_len = s->static_len = 0L;
424 s->last_lit = s->matches = 0;
425 }
426
427 #define SMALLEST 1
428 /* Index within the heap array of least frequent node in the Huffman tree */
429
430
431 /* ===========================================================================
432 * Remove the smallest element from the heap and recreate the heap with
433 * one less element. Updates heap and heap_len.
434 */
435 #define pqremove(s, tree, top) \
436 {\
437 top = s->heap[SMALLEST]; \
438 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
439 pqdownheap(s, tree, SMALLEST); \
440 }
441
442 /* ===========================================================================
443 * Compares to subtrees, using the tree depth as tie breaker when
444 * the subtrees have equal frequency. This minimizes the worst case length.
445 */
446 #define smaller(tree, n, m, depth) \
447 (tree[n].Freq < tree[m].Freq || \
448 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
449
450 /* ===========================================================================
451 * Restore the heap property by moving down the tree starting at node k,
452 * exchanging a node with the smallest of its two sons if necessary, stopping
453 * when the heap property is re-established (each father smaller than its
454 * two sons).
455 */
456 local void pqdownheap(s, tree, k)
457 deflate_state *s;
458 ct_data *tree; /* the tree to restore */
459 int k; /* node to move down */
460 {
461 int v = s->heap[k];
462 int j = k << 1; /* left son of k */
463 while (j <= s->heap_len) {
464 /* Set j to the smallest of the two sons: */
465 if (j < s->heap_len &&
466 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
467 j++;
468 }
469 /* Exit if v is smaller than both sons */
470 if (smaller(tree, v, s->heap[j], s->depth)) break;
471
472 /* Exchange v with the smallest son */
473 s->heap[k] = s->heap[j]; k = j;
474
475 /* And continue down the tree, setting j to the left son of k */
476 j <<= 1;
477 }
478 s->heap[k] = v;
479 }
480
481 /* ===========================================================================
482 * Compute the optimal bit lengths for a tree and update the total bit length
483 * for the current block.
484 * IN assertion: the fields freq and dad are set, heap[heap_max] and
485 * above are the tree nodes sorted by increasing frequency.
486 * OUT assertions: the field len is set to the optimal bit length, the
487 * array bl_count contains the frequencies for each bit length.
488 * The length opt_len is updated; static_len is also updated if stree is
489 * not null.
490 */
491 local void gen_bitlen(s, desc)
492 deflate_state *s;
493 tree_desc *desc; /* the tree descriptor */
494 {
495 ct_data *tree = desc->dyn_tree;
496 int max_code = desc->max_code;
497 const ct_data *stree = desc->stat_desc->static_tree;
498 const intf *extra = desc->stat_desc->extra_bits;
499 int base = desc->stat_desc->extra_base;
500 int max_length = desc->stat_desc->max_length;
501 int h; /* heap index */
502 int n, m; /* iterate over the tree elements */
503 int bits; /* bit length */
504 int xbits; /* extra bits */
505 ush f; /* frequency */
506 int overflow = 0; /* number of elements with bit length too large */
507
508 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
509
510 /* In a first pass, compute the optimal bit lengths (which may
511 * overflow in the case of the bit length tree).
512 */
513 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
514
515 for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
516 n = s->heap[h];
517 bits = tree[tree[n].Dad].Len + 1;
518 if (bits > max_length) bits = max_length, overflow++;
519 tree[n].Len = (ush)bits;
520 /* We overwrite tree[n].Dad which is no longer needed */
521
522 if (n > max_code) continue; /* not a leaf node */
523
524 s->bl_count[bits]++;
525 xbits = 0;
526 if (n >= base) xbits = extra[n-base];
527 f = tree[n].Freq;
528 s->opt_len += (ulg)f * (bits + xbits);
529 if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
530 }
531 if (overflow == 0) return;
532
533 Trace((stderr,"\nbit length overflow\n"));
534 /* This happens for example on obj2 and pic of the Calgary corpus */
535
536 /* Find the first bit length which could increase: */
537 do {
538 bits = max_length-1;
539 while (s->bl_count[bits] == 0) bits--;
540 s->bl_count[bits]--; /* move one leaf down the tree */
541 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
542 s->bl_count[max_length]--;
543 /* The brother of the overflow item also moves one step up,
544 * but this does not affect bl_count[max_length]
545 */
546 overflow -= 2;
547 } while (overflow > 0);
548
549 /* Now recompute all bit lengths, scanning in increasing frequency.
550 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
551 * lengths instead of fixing only the wrong ones. This idea is taken
552 * from 'ar' written by Haruhiko Okumura.)
553 */
554 for (bits = max_length; bits != 0; bits--) {
555 n = s->bl_count[bits];
556 while (n != 0) {
557 m = s->heap[--h];
558 if (m > max_code) continue;
559 if (tree[m].Len != (unsigned) bits) {
560 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
561 s->opt_len += ((long)bits - (long)tree[m].Len)
562 *(long)tree[m].Freq;
563 tree[m].Len = (ush)bits;
564 }
565 n--;
566 }
567 }
568 }
569
570 /* ===========================================================================
571 * Generate the codes for a given tree and bit counts (which need not be
572 * optimal).
573 * IN assertion: the array bl_count contains the bit length statistics for
574 * the given tree and the field len is set for all tree elements.
575 * OUT assertion: the field code is set for all tree elements of non
576 * zero code length.
577 */
578 local void gen_codes (tree, max_code, bl_count)
579 ct_data *tree; /* the tree to decorate */
580 int max_code; /* largest code with non zero frequency */
581 ushf *bl_count; /* number of codes at each bit length */
582 {
583 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
584 ush code = 0; /* running code value */
585 int bits; /* bit index */
586 int n; /* code index */
587
588 /* The distribution counts are first used to generate the code values
589 * without bit reversal.
590 */
591 for (bits = 1; bits <= MAX_BITS; bits++) {
592 next_code[bits] = code = (code + bl_count[bits-1]) << 1;
593 }
594 /* Check that the bit counts in bl_count are consistent. The last code
595 * must be all ones.
596 */
597 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
598 "inconsistent bit counts");
599 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
600
601 for (n = 0; n <= max_code; n++) {
602 int len = tree[n].Len;
603 if (len == 0) continue;
604 /* Now reverse the bits */
605 tree[n].Code = bi_reverse(next_code[len]++, len);
606
607 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
608 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
609 }
610 }
611
612 /* ===========================================================================
613 * Construct one Huffman tree and assigns the code bit strings and lengths.
614 * Update the total bit length for the current block.
615 * IN assertion: the field freq is set for all tree elements.
616 * OUT assertions: the fields len and code are set to the optimal bit length
617 * and corresponding code. The length opt_len is updated; static_len is
618 * also updated if stree is not null. The field max_code is set.
619 */
620 local void build_tree(s, desc)
621 deflate_state *s;
622 tree_desc *desc; /* the tree descriptor */
623 {
624 ct_data *tree = desc->dyn_tree;
625 const ct_data *stree = desc->stat_desc->static_tree;
626 int elems = desc->stat_desc->elems;
627 int n, m; /* iterate over heap elements */
628 int max_code = -1; /* largest code with non zero frequency */
629 int node; /* new node being created */
630
631 /* Construct the initial heap, with least frequent element in
632 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
633 * heap[0] is not used.
634 */
635 s->heap_len = 0, s->heap_max = HEAP_SIZE;
636
637 for (n = 0; n < elems; n++) {
638 if (tree[n].Freq != 0) {
639 s->heap[++(s->heap_len)] = max_code = n;
640 s->depth[n] = 0;
641 } else {
642 tree[n].Len = 0;
643 }
644 }
645
646 /* The pkzip format requires that at least one distance code exists,
647 * and that at least one bit should be sent even if there is only one
648 * possible code. So to avoid special checks later on we force at least
649 * two codes of non zero frequency.
650 */
651 while (s->heap_len < 2) {
652 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
653 tree[node].Freq = 1;
654 s->depth[node] = 0;
655 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
656 /* node is 0 or 1 so it does not have extra bits */
657 }
658 desc->max_code = max_code;
659
660 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
661 * establish sub-heaps of increasing lengths:
662 */
663 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
664
665 /* Construct the Huffman tree by repeatedly combining the least two
666 * frequent nodes.
667 */
668 node = elems; /* next internal node of the tree */
669 do {
670 pqremove(s, tree, n); /* n = node of least frequency */
671 m = s->heap[SMALLEST]; /* m = node of next least frequency */
672
673 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
674 s->heap[--(s->heap_max)] = m;
675
676 /* Create a new node father of n and m */
677 tree[node].Freq = tree[n].Freq + tree[m].Freq;
678 s->depth[node] = (uch) (MAX(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 ascii or binary */
934 if (s->data_type == Z_UNKNOWN) set_data_type(s);
935
936 /* Construct the literal and distance trees */
937 build_tree(s, (tree_desc *)(&(s->l_desc)));
938 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
939 s->static_len));
940
941 build_tree(s, (tree_desc *)(&(s->d_desc)));
942 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
943 s->static_len));
944 /* At this point, opt_len and static_len are the total bit lengths of
945 * the compressed block data, excluding the tree representations.
946 */
947
948 /* Build the bit length tree for the above two trees, and get the index
949 * in bl_order of the last bit length code to send.
950 */
951 max_blindex = build_bl_tree(s);
952
953 /* Determine the best encoding. Compute first the block length in bytes*/
954 opt_lenb = (s->opt_len+3+7)>>3;
955 static_lenb = (s->static_len+3+7)>>3;
956
957 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
958 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
959 s->last_lit));
960
961 if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
962
963 } else {
964 Assert(buf != (char*)0, "lost buf");
965 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
966 }
967
968 #ifdef FORCE_STORED
969 if (buf != (char*)0) { /* force stored block */
970 #else
971 if (stored_len+4 <= opt_lenb && buf != (char*)0) {
972 /* 4: two words for the lengths */
973 #endif
974 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
975 * Otherwise we can't have processed more than WSIZE input bytes since
976 * the last block flush, because compression would have been
977 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
978 * transform a block into a stored block.
979 */
980 _tr_stored_block(s, buf, stored_len, eof);
981
982 #ifdef FORCE_STATIC
983 } else if (static_lenb >= 0) { /* force static trees */
984 #else
985 } else if (static_lenb == opt_lenb) {
986 #endif
987 send_bits(s, (STATIC_TREES<<1)+eof, 3);
988 compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
989 #ifdef DEBUG
990 s->compressed_len += 3 + s->static_len;
991 #endif
992 } else {
993 send_bits(s, (DYN_TREES<<1)+eof, 3);
994 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
995 max_blindex+1);
996 compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
997 #ifdef DEBUG
998 s->compressed_len += 3 + s->opt_len;
999 #endif
1000 }
1001 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1002 /* The above check is made mod 2^32, for files larger than 512 MB
1003 * and uLong implemented on 32 bits.
1004 */
1005 init_block(s);
1006
1007 if (eof) {
1008 bi_windup(s);
1009 #ifdef DEBUG
1010 s->compressed_len += 7; /* align on byte boundary */
1011 #endif
1012 }
1013 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1014 s->compressed_len-7*eof));
1015 }
1016
1017 /* ===========================================================================
1018 * Save the match info and tally the frequency counts. Return true if
1019 * the current block must be flushed.
1020 */
1021 int _tr_tally (s, dist, lc)
1022 deflate_state *s;
1023 unsigned dist; /* distance of matched string */
1024 unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1025 {
1026 s->d_buf[s->last_lit] = (ush)dist;
1027 s->l_buf[s->last_lit++] = (uch)lc;
1028 if (dist == 0) {
1029 /* lc is the unmatched char */
1030 s->dyn_ltree[lc].Freq++;
1031 } else {
1032 s->matches++;
1033 /* Here, lc is the match length - MIN_MATCH */
1034 dist--; /* dist = match distance - 1 */
1035 Assert((ush)dist < (ush)MAX_DIST(s) &&
1036 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1037 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1038
1039 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1040 s->dyn_dtree[d_code(dist)].Freq++;
1041 }
1042
1043 #ifdef TRUNCATE_BLOCK
1044 /* Try to guess if it is profitable to stop the current block here */
1045 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1046 /* Compute an upper bound for the compressed length */
1047 ulg out_length = (ulg)s->last_lit*8L;
1048 ulg in_length = (ulg)((long)s->strstart - s->block_start);
1049 int dcode;
1050 for (dcode = 0; dcode < D_CODES; dcode++) {
1051 out_length += (ulg)s->dyn_dtree[dcode].Freq *
1052 (5L+extra_dbits[dcode]);
1053 }
1054 out_length >>= 3;
1055 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1056 s->last_lit, in_length, out_length,
1057 100L - out_length*100L/in_length));
1058 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1059 }
1060 #endif
1061 return (s->last_lit == s->lit_bufsize-1);
1062 /* We avoid equality with lit_bufsize because of wraparound at 64K
1063 * on 16 bit machines and because stored blocks are restricted to
1064 * 64K-1 bytes.
1065 */
1066 }
1067
1068 /* ===========================================================================
1069 * Send the block data compressed using the given Huffman trees
1070 */
1071 local void compress_block(s, ltree, dtree)
1072 deflate_state *s;
1073 ct_data *ltree; /* literal tree */
1074 ct_data *dtree; /* distance tree */
1075 {
1076 unsigned dist; /* distance of matched string */
1077 int lc; /* match length or unmatched char (if dist == 0) */
1078 unsigned lx = 0; /* running index in l_buf */
1079 unsigned code; /* the code to send */
1080 int extra; /* number of extra bits to send */
1081
1082 if (s->last_lit != 0) do {
1083 dist = s->d_buf[lx];
1084 lc = s->l_buf[lx++];
1085 if (dist == 0) {
1086 send_code(s, lc, ltree); /* send a literal byte */
1087 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1088 } else {
1089 /* Here, lc is the match length - MIN_MATCH */
1090 code = _length_code[lc];
1091 send_code(s, code+LITERALS+1, ltree); /* send the length code */
1092 extra = extra_lbits[code];
1093 if (extra != 0) {
1094 lc -= base_length[code];
1095 send_bits(s, lc, extra); /* send the extra length bits */
1096 }
1097 dist--; /* dist is now the match distance - 1 */
1098 code = d_code(dist);
1099 Assert (code < D_CODES, "bad d_code");
1100
1101 send_code(s, code, dtree); /* send the distance code */
1102 extra = extra_dbits[code];
1103 if (extra != 0) {
1104 dist -= base_dist[code];
1105 send_bits(s, dist, extra); /* send the extra distance bits */
1106 }
1107 } /* literal or match pair ? */
1108
1109 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1110 Assert(s->pending < s->lit_bufsize + 2*lx, "pendingBuf overflow");
1111
1112 } while (lx < s->last_lit);
1113
1114 send_code(s, END_BLOCK, ltree);
1115 s->last_eob_len = ltree[END_BLOCK].Len;
1116 }
1117
1118 /* ===========================================================================
1119 * Set the data type to ASCII or BINARY, using a crude approximation:
1120 * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
1121 * IN assertion: the fields freq of dyn_ltree are set and the total of all
1122 * frequencies does not exceed 64K (to fit in an int on 16 bit machines).
1123 */
1124 local void set_data_type(s)
1125 deflate_state *s;
1126 {
1127 int n = 0;
1128 unsigned ascii_freq = 0;
1129 unsigned bin_freq = 0;
1130 while (n < 7) bin_freq += s->dyn_ltree[n++].Freq;
1131 while (n < 128) ascii_freq += s->dyn_ltree[n++].Freq;
1132 while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq;
1133 s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? Z_BINARY : Z_ASCII);
1134 }
1135
1136 /* ===========================================================================
1137 * Reverse the first len bits of a code, using straightforward code (a faster
1138 * method would use a table)
1139 * IN assertion: 1 <= len <= 15
1140 */
1141 local unsigned bi_reverse(code, len)
1142 unsigned code; /* the value to invert */
1143 int len; /* its bit length */
1144 {
1145 register unsigned res = 0;
1146 do {
1147 res |= code & 1;
1148 code >>= 1, res <<= 1;
1149 } while (--len > 0);
1150 return res >> 1;
1151 }
1152
1153 /* ===========================================================================
1154 * Flush the bit buffer, keeping at most 7 bits in it.
1155 */
1156 local void bi_flush(s)
1157 deflate_state *s;
1158 {
1159 if (s->bi_valid == 16) {
1160 put_short(s, s->bi_buf);
1161 s->bi_buf = 0;
1162 s->bi_valid = 0;
1163 } else if (s->bi_valid >= 8) {
1164 put_byte(s, (Byte)s->bi_buf);
1165 s->bi_buf >>= 8;
1166 s->bi_valid -= 8;
1167 }
1168 }
1169
1170 /* ===========================================================================
1171 * Flush the bit buffer and align the output on a byte boundary
1172 */
1173 local void bi_windup(s)
1174 deflate_state *s;
1175 {
1176 if (s->bi_valid > 8) {
1177 put_short(s, s->bi_buf);
1178 } else if (s->bi_valid > 0) {
1179 put_byte(s, (Byte)s->bi_buf);
1180 }
1181 s->bi_buf = 0;
1182 s->bi_valid = 0;
1183 #ifdef DEBUG
1184 s->bits_sent = (s->bits_sent+7) & ~7;
1185 #endif
1186 }
1187
1188 /* ===========================================================================
1189 * Copy a stored block, storing first the length and its
1190 * one's complement if requested.
1191 */
1192 local void copy_block(s, buf, len, header)
1193 deflate_state *s;
1194 charf *buf; /* the input data */
1195 unsigned len; /* its length */
1196 int header; /* true if block header must be written */
1197 {
1198 bi_windup(s); /* align on byte boundary */
1199 s->last_eob_len = 8; /* enough lookahead for inflate */
1200
1201 if (header) {
1202 put_short(s, (ush)len);
1203 put_short(s, (ush)~len);
1204 #ifdef DEBUG
1205 s->bits_sent += 2*16;
1206 #endif
1207 }
1208 #ifdef DEBUG
1209 s->bits_sent += (ulg)len<<3;
1210 #endif
1211 while (len--) {
1212 put_byte(s, *buf++);
1213 }
1214 }