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ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4. The directory name has changed: no version number in the expanded directory now.
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:43:07 +0200
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1:1d09e1dec1d9 2:b50eed0cc0ef
1 /* trees.c -- output deflated data using Huffman coding
2 * Copyright (C) 1995-2024 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 ZLIB_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 #ifdef NO_INIT_GLOBAL_POINTERS
126 # define TCONST
127 #else
128 # define TCONST const
129 #endif
130
131 local TCONST static_tree_desc static_l_desc =
132 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
133
134 local TCONST static_tree_desc static_d_desc =
135 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
136
137 local TCONST static_tree_desc static_bl_desc =
138 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
139
140 /* ===========================================================================
141 * Output a short LSB first on the stream.
142 * IN assertion: there is enough room in pendingBuf.
143 */
144 #define put_short(s, w) { \
145 put_byte(s, (uch)((w) & 0xff)); \
146 put_byte(s, (uch)((ush)(w) >> 8)); \
147 }
148
149 /* ===========================================================================
150 * Reverse the first len bits of a code, using straightforward code (a faster
151 * method would use a table)
152 * IN assertion: 1 <= len <= 15
153 */
154 local unsigned bi_reverse(unsigned code, int len) {
155 register unsigned res = 0;
156 do {
157 res |= code & 1;
158 code >>= 1, res <<= 1;
159 } while (--len > 0);
160 return res >> 1;
161 }
162
163 /* ===========================================================================
164 * Flush the bit buffer, keeping at most 7 bits in it.
165 */
166 local void bi_flush(deflate_state *s) {
167 if (s->bi_valid == 16) {
168 put_short(s, s->bi_buf);
169 s->bi_buf = 0;
170 s->bi_valid = 0;
171 } else if (s->bi_valid >= 8) {
172 put_byte(s, (Byte)s->bi_buf);
173 s->bi_buf >>= 8;
174 s->bi_valid -= 8;
175 }
176 }
177
178 /* ===========================================================================
179 * Flush the bit buffer and align the output on a byte boundary
180 */
181 local void bi_windup(deflate_state *s) {
182 if (s->bi_valid > 8) {
183 put_short(s, s->bi_buf);
184 } else if (s->bi_valid > 0) {
185 put_byte(s, (Byte)s->bi_buf);
186 }
187 s->bi_buf = 0;
188 s->bi_valid = 0;
189 #ifdef ZLIB_DEBUG
190 s->bits_sent = (s->bits_sent + 7) & ~7;
191 #endif
192 }
193
194 /* ===========================================================================
195 * Generate the codes for a given tree and bit counts (which need not be
196 * optimal).
197 * IN assertion: the array bl_count contains the bit length statistics for
198 * the given tree and the field len is set for all tree elements.
199 * OUT assertion: the field code is set for all tree elements of non
200 * zero code length.
201 */
202 local void gen_codes(ct_data *tree, int max_code, ushf *bl_count) {
203 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
204 unsigned code = 0; /* running code value */
205 int bits; /* bit index */
206 int n; /* code index */
207
208 /* The distribution counts are first used to generate the code values
209 * without bit reversal.
210 */
211 for (bits = 1; bits <= MAX_BITS; bits++) {
212 code = (code + bl_count[bits - 1]) << 1;
213 next_code[bits] = (ush)code;
214 }
215 /* Check that the bit counts in bl_count are consistent. The last code
216 * must be all ones.
217 */
218 Assert (code + bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
219 "inconsistent bit counts");
220 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
221
222 for (n = 0; n <= max_code; n++) {
223 int len = tree[n].Len;
224 if (len == 0) continue;
225 /* Now reverse the bits */
226 tree[n].Code = (ush)bi_reverse(next_code[len]++, len);
227
228 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
229 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len] - 1));
230 }
231 }
232
233 #ifdef GEN_TREES_H
234 local void gen_trees_header(void);
235 #endif
236
237 #ifndef ZLIB_DEBUG
238 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
239 /* Send a code of the given tree. c and tree must not have side effects */
240
241 #else /* !ZLIB_DEBUG */
242 # define send_code(s, c, tree) \
243 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
244 send_bits(s, tree[c].Code, tree[c].Len); }
245 #endif
246
247 /* ===========================================================================
248 * Send a value on a given number of bits.
249 * IN assertion: length <= 16 and value fits in length bits.
250 */
251 #ifdef ZLIB_DEBUG
252 local void send_bits(deflate_state *s, int value, int length) {
253 Tracevv((stderr," l %2d v %4x ", length, value));
254 Assert(length > 0 && length <= 15, "invalid length");
255 s->bits_sent += (ulg)length;
256
257 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
258 * (16 - bi_valid) bits from value, leaving (width - (16 - bi_valid))
259 * unused bits in value.
260 */
261 if (s->bi_valid > (int)Buf_size - length) {
262 s->bi_buf |= (ush)value << s->bi_valid;
263 put_short(s, s->bi_buf);
264 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
265 s->bi_valid += length - Buf_size;
266 } else {
267 s->bi_buf |= (ush)value << s->bi_valid;
268 s->bi_valid += length;
269 }
270 }
271 #else /* !ZLIB_DEBUG */
272
273 #define send_bits(s, value, length) \
274 { int len = length;\
275 if (s->bi_valid > (int)Buf_size - len) {\
276 int val = (int)value;\
277 s->bi_buf |= (ush)val << s->bi_valid;\
278 put_short(s, s->bi_buf);\
279 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
280 s->bi_valid += len - Buf_size;\
281 } else {\
282 s->bi_buf |= (ush)(value) << s->bi_valid;\
283 s->bi_valid += len;\
284 }\
285 }
286 #endif /* ZLIB_DEBUG */
287
288
289 /* the arguments must not have side effects */
290
291 /* ===========================================================================
292 * Initialize the various 'constant' tables.
293 */
294 local void tr_static_init(void) {
295 #if defined(GEN_TREES_H) || !defined(STDC)
296 static int static_init_done = 0;
297 int n; /* iterates over tree elements */
298 int bits; /* bit counter */
299 int length; /* length value */
300 int code; /* code value */
301 int dist; /* distance index */
302 ush bl_count[MAX_BITS+1];
303 /* number of codes at each bit length for an optimal tree */
304
305 if (static_init_done) return;
306
307 /* For some embedded targets, global variables are not initialized: */
308 #ifdef NO_INIT_GLOBAL_POINTERS
309 static_l_desc.static_tree = static_ltree;
310 static_l_desc.extra_bits = extra_lbits;
311 static_d_desc.static_tree = static_dtree;
312 static_d_desc.extra_bits = extra_dbits;
313 static_bl_desc.extra_bits = extra_blbits;
314 #endif
315
316 /* Initialize the mapping length (0..255) -> length code (0..28) */
317 length = 0;
318 for (code = 0; code < LENGTH_CODES-1; code++) {
319 base_length[code] = length;
320 for (n = 0; n < (1 << extra_lbits[code]); n++) {
321 _length_code[length++] = (uch)code;
322 }
323 }
324 Assert (length == 256, "tr_static_init: length != 256");
325 /* Note that the length 255 (match length 258) can be represented
326 * in two different ways: code 284 + 5 bits or code 285, so we
327 * overwrite length_code[255] to use the best encoding:
328 */
329 _length_code[length - 1] = (uch)code;
330
331 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
332 dist = 0;
333 for (code = 0 ; code < 16; code++) {
334 base_dist[code] = dist;
335 for (n = 0; n < (1 << extra_dbits[code]); n++) {
336 _dist_code[dist++] = (uch)code;
337 }
338 }
339 Assert (dist == 256, "tr_static_init: dist != 256");
340 dist >>= 7; /* from now on, all distances are divided by 128 */
341 for ( ; code < D_CODES; code++) {
342 base_dist[code] = dist << 7;
343 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
344 _dist_code[256 + dist++] = (uch)code;
345 }
346 }
347 Assert (dist == 256, "tr_static_init: 256 + dist != 512");
348
349 /* Construct the codes of the static literal tree */
350 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
351 n = 0;
352 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
353 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
354 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
355 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
356 /* Codes 286 and 287 do not exist, but we must include them in the
357 * tree construction to get a canonical Huffman tree (longest code
358 * all ones)
359 */
360 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
361
362 /* The static distance tree is trivial: */
363 for (n = 0; n < D_CODES; n++) {
364 static_dtree[n].Len = 5;
365 static_dtree[n].Code = bi_reverse((unsigned)n, 5);
366 }
367 static_init_done = 1;
368
369 # ifdef GEN_TREES_H
370 gen_trees_header();
371 # endif
372 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
373 }
374
375 /* ===========================================================================
376 * Generate the file trees.h describing the static trees.
377 */
378 #ifdef GEN_TREES_H
379 # ifndef ZLIB_DEBUG
380 # include <stdio.h>
381 # endif
382
383 # define SEPARATOR(i, last, width) \
384 ((i) == (last)? "\n};\n\n" : \
385 ((i) % (width) == (width) - 1 ? ",\n" : ", "))
386
387 void gen_trees_header(void) {
388 FILE *header = fopen("trees.h", "w");
389 int i;
390
391 Assert (header != NULL, "Can't open trees.h");
392 fprintf(header,
393 "/* header created automatically with -DGEN_TREES_H */\n\n");
394
395 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
396 for (i = 0; i < L_CODES+2; i++) {
397 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
398 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
399 }
400
401 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
402 for (i = 0; i < D_CODES; i++) {
403 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
404 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
405 }
406
407 fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
408 for (i = 0; i < DIST_CODE_LEN; i++) {
409 fprintf(header, "%2u%s", _dist_code[i],
410 SEPARATOR(i, DIST_CODE_LEN-1, 20));
411 }
412
413 fprintf(header,
414 "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
415 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
416 fprintf(header, "%2u%s", _length_code[i],
417 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
418 }
419
420 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
421 for (i = 0; i < LENGTH_CODES; i++) {
422 fprintf(header, "%1u%s", base_length[i],
423 SEPARATOR(i, LENGTH_CODES-1, 20));
424 }
425
426 fprintf(header, "local const int base_dist[D_CODES] = {\n");
427 for (i = 0; i < D_CODES; i++) {
428 fprintf(header, "%5u%s", base_dist[i],
429 SEPARATOR(i, D_CODES-1, 10));
430 }
431
432 fclose(header);
433 }
434 #endif /* GEN_TREES_H */
435
436 /* ===========================================================================
437 * Initialize a new block.
438 */
439 local void init_block(deflate_state *s) {
440 int n; /* iterates over tree elements */
441
442 /* Initialize the trees. */
443 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
444 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
445 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
446
447 s->dyn_ltree[END_BLOCK].Freq = 1;
448 s->opt_len = s->static_len = 0L;
449 s->sym_next = s->matches = 0;
450 }
451
452 /* ===========================================================================
453 * Initialize the tree data structures for a new zlib stream.
454 */
455 void ZLIB_INTERNAL _tr_init(deflate_state *s) {
456 tr_static_init();
457
458 s->l_desc.dyn_tree = s->dyn_ltree;
459 s->l_desc.stat_desc = &static_l_desc;
460
461 s->d_desc.dyn_tree = s->dyn_dtree;
462 s->d_desc.stat_desc = &static_d_desc;
463
464 s->bl_desc.dyn_tree = s->bl_tree;
465 s->bl_desc.stat_desc = &static_bl_desc;
466
467 s->bi_buf = 0;
468 s->bi_valid = 0;
469 #ifdef ZLIB_DEBUG
470 s->compressed_len = 0L;
471 s->bits_sent = 0L;
472 #endif
473
474 /* Initialize the first block of the first file: */
475 init_block(s);
476 }
477
478 #define SMALLEST 1
479 /* Index within the heap array of least frequent node in the Huffman tree */
480
481
482 /* ===========================================================================
483 * Remove the smallest element from the heap and recreate the heap with
484 * one less element. Updates heap and heap_len.
485 */
486 #define pqremove(s, tree, top) \
487 {\
488 top = s->heap[SMALLEST]; \
489 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
490 pqdownheap(s, tree, SMALLEST); \
491 }
492
493 /* ===========================================================================
494 * Compares to subtrees, using the tree depth as tie breaker when
495 * the subtrees have equal frequency. This minimizes the worst case length.
496 */
497 #define smaller(tree, n, m, depth) \
498 (tree[n].Freq < tree[m].Freq || \
499 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
500
501 /* ===========================================================================
502 * Restore the heap property by moving down the tree starting at node k,
503 * exchanging a node with the smallest of its two sons if necessary, stopping
504 * when the heap property is re-established (each father smaller than its
505 * two sons).
506 */
507 local void pqdownheap(deflate_state *s, ct_data *tree, int k) {
508 int v = s->heap[k];
509 int j = k << 1; /* left son of k */
510 while (j <= s->heap_len) {
511 /* Set j to the smallest of the two sons: */
512 if (j < s->heap_len &&
513 smaller(tree, s->heap[j + 1], s->heap[j], s->depth)) {
514 j++;
515 }
516 /* Exit if v is smaller than both sons */
517 if (smaller(tree, v, s->heap[j], s->depth)) break;
518
519 /* Exchange v with the smallest son */
520 s->heap[k] = s->heap[j]; k = j;
521
522 /* And continue down the tree, setting j to the left son of k */
523 j <<= 1;
524 }
525 s->heap[k] = v;
526 }
527
528 /* ===========================================================================
529 * Compute the optimal bit lengths for a tree and update the total bit length
530 * for the current block.
531 * IN assertion: the fields freq and dad are set, heap[heap_max] and
532 * above are the tree nodes sorted by increasing frequency.
533 * OUT assertions: the field len is set to the optimal bit length, the
534 * array bl_count contains the frequencies for each bit length.
535 * The length opt_len is updated; static_len is also updated if stree is
536 * not null.
537 */
538 local void gen_bitlen(deflate_state *s, tree_desc *desc) {
539 ct_data *tree = desc->dyn_tree;
540 int max_code = desc->max_code;
541 const ct_data *stree = desc->stat_desc->static_tree;
542 const intf *extra = desc->stat_desc->extra_bits;
543 int base = desc->stat_desc->extra_base;
544 int max_length = desc->stat_desc->max_length;
545 int h; /* heap index */
546 int n, m; /* iterate over the tree elements */
547 int bits; /* bit length */
548 int xbits; /* extra bits */
549 ush f; /* frequency */
550 int overflow = 0; /* number of elements with bit length too large */
551
552 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
553
554 /* In a first pass, compute the optimal bit lengths (which may
555 * overflow in the case of the bit length tree).
556 */
557 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
558
559 for (h = s->heap_max + 1; h < HEAP_SIZE; h++) {
560 n = s->heap[h];
561 bits = tree[tree[n].Dad].Len + 1;
562 if (bits > max_length) bits = max_length, overflow++;
563 tree[n].Len = (ush)bits;
564 /* We overwrite tree[n].Dad which is no longer needed */
565
566 if (n > max_code) continue; /* not a leaf node */
567
568 s->bl_count[bits]++;
569 xbits = 0;
570 if (n >= base) xbits = extra[n - base];
571 f = tree[n].Freq;
572 s->opt_len += (ulg)f * (unsigned)(bits + xbits);
573 if (stree) s->static_len += (ulg)f * (unsigned)(stree[n].Len + xbits);
574 }
575 if (overflow == 0) return;
576
577 Tracev((stderr,"\nbit length overflow\n"));
578 /* This happens for example on obj2 and pic of the Calgary corpus */
579
580 /* Find the first bit length which could increase: */
581 do {
582 bits = max_length - 1;
583 while (s->bl_count[bits] == 0) bits--;
584 s->bl_count[bits]--; /* move one leaf down the tree */
585 s->bl_count[bits + 1] += 2; /* move one overflow item as its brother */
586 s->bl_count[max_length]--;
587 /* The brother of the overflow item also moves one step up,
588 * but this does not affect bl_count[max_length]
589 */
590 overflow -= 2;
591 } while (overflow > 0);
592
593 /* Now recompute all bit lengths, scanning in increasing frequency.
594 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
595 * lengths instead of fixing only the wrong ones. This idea is taken
596 * from 'ar' written by Haruhiko Okumura.)
597 */
598 for (bits = max_length; bits != 0; bits--) {
599 n = s->bl_count[bits];
600 while (n != 0) {
601 m = s->heap[--h];
602 if (m > max_code) continue;
603 if ((unsigned) tree[m].Len != (unsigned) bits) {
604 Tracev((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
605 s->opt_len += ((ulg)bits - tree[m].Len) * tree[m].Freq;
606 tree[m].Len = (ush)bits;
607 }
608 n--;
609 }
610 }
611 }
612
613 #ifdef DUMP_BL_TREE
614 # include <stdio.h>
615 #endif
616
617 /* ===========================================================================
618 * Construct one Huffman tree and assigns the code bit strings and lengths.
619 * Update the total bit length for the current block.
620 * IN assertion: the field freq is set for all tree elements.
621 * OUT assertions: the fields len and code are set to the optimal bit length
622 * and corresponding code. The length opt_len is updated; static_len is
623 * also updated if stree is not null. The field max_code is set.
624 */
625 local void build_tree(deflate_state *s, tree_desc *desc) {
626 ct_data *tree = desc->dyn_tree;
627 const ct_data *stree = desc->stat_desc->static_tree;
628 int elems = desc->stat_desc->elems;
629 int n, m; /* iterate over heap elements */
630 int max_code = -1; /* largest code with non zero frequency */
631 int node; /* new node being created */
632
633 /* Construct the initial heap, with least frequent element in
634 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n + 1].
635 * heap[0] is not used.
636 */
637 s->heap_len = 0, s->heap_max = HEAP_SIZE;
638
639 for (n = 0; n < elems; n++) {
640 if (tree[n].Freq != 0) {
641 s->heap[++(s->heap_len)] = max_code = n;
642 s->depth[n] = 0;
643 } else {
644 tree[n].Len = 0;
645 }
646 }
647
648 /* The pkzip format requires that at least one distance code exists,
649 * and that at least one bit should be sent even if there is only one
650 * possible code. So to avoid special checks later on we force at least
651 * two codes of non zero frequency.
652 */
653 while (s->heap_len < 2) {
654 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
655 tree[node].Freq = 1;
656 s->depth[node] = 0;
657 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
658 /* node is 0 or 1 so it does not have extra bits */
659 }
660 desc->max_code = max_code;
661
662 /* The elements heap[heap_len/2 + 1 .. heap_len] are leaves of the tree,
663 * establish sub-heaps of increasing lengths:
664 */
665 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
666
667 /* Construct the Huffman tree by repeatedly combining the least two
668 * frequent nodes.
669 */
670 node = elems; /* next internal node of the tree */
671 do {
672 pqremove(s, tree, n); /* n = node of least frequency */
673 m = s->heap[SMALLEST]; /* m = node of next least frequency */
674
675 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
676 s->heap[--(s->heap_max)] = m;
677
678 /* Create a new node father of n and m */
679 tree[node].Freq = tree[n].Freq + tree[m].Freq;
680 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
681 s->depth[n] : s->depth[m]) + 1);
682 tree[n].Dad = tree[m].Dad = (ush)node;
683 #ifdef DUMP_BL_TREE
684 if (tree == s->bl_tree) {
685 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
686 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
687 }
688 #endif
689 /* and insert the new node in the heap */
690 s->heap[SMALLEST] = node++;
691 pqdownheap(s, tree, SMALLEST);
692
693 } while (s->heap_len >= 2);
694
695 s->heap[--(s->heap_max)] = s->heap[SMALLEST];
696
697 /* At this point, the fields freq and dad are set. We can now
698 * generate the bit lengths.
699 */
700 gen_bitlen(s, (tree_desc *)desc);
701
702 /* The field len is now set, we can generate the bit codes */
703 gen_codes ((ct_data *)tree, max_code, s->bl_count);
704 }
705
706 /* ===========================================================================
707 * Scan a literal or distance tree to determine the frequencies of the codes
708 * in the bit length tree.
709 */
710 local void scan_tree(deflate_state *s, ct_data *tree, int max_code) {
711 int n; /* iterates over all tree elements */
712 int prevlen = -1; /* last emitted length */
713 int curlen; /* length of current code */
714 int nextlen = tree[0].Len; /* length of next code */
715 int count = 0; /* repeat count of the current code */
716 int max_count = 7; /* max repeat count */
717 int min_count = 4; /* min repeat count */
718
719 if (nextlen == 0) max_count = 138, min_count = 3;
720 tree[max_code + 1].Len = (ush)0xffff; /* guard */
721
722 for (n = 0; n <= max_code; n++) {
723 curlen = nextlen; nextlen = tree[n + 1].Len;
724 if (++count < max_count && curlen == nextlen) {
725 continue;
726 } else if (count < min_count) {
727 s->bl_tree[curlen].Freq += count;
728 } else if (curlen != 0) {
729 if (curlen != prevlen) s->bl_tree[curlen].Freq++;
730 s->bl_tree[REP_3_6].Freq++;
731 } else if (count <= 10) {
732 s->bl_tree[REPZ_3_10].Freq++;
733 } else {
734 s->bl_tree[REPZ_11_138].Freq++;
735 }
736 count = 0; prevlen = curlen;
737 if (nextlen == 0) {
738 max_count = 138, min_count = 3;
739 } else if (curlen == nextlen) {
740 max_count = 6, min_count = 3;
741 } else {
742 max_count = 7, min_count = 4;
743 }
744 }
745 }
746
747 /* ===========================================================================
748 * Send a literal or distance tree in compressed form, using the codes in
749 * bl_tree.
750 */
751 local void send_tree(deflate_state *s, ct_data *tree, int max_code) {
752 int n; /* iterates over all tree elements */
753 int prevlen = -1; /* last emitted length */
754 int curlen; /* length of current code */
755 int nextlen = tree[0].Len; /* length of next code */
756 int count = 0; /* repeat count of the current code */
757 int max_count = 7; /* max repeat count */
758 int min_count = 4; /* min repeat count */
759
760 /* tree[max_code + 1].Len = -1; */ /* guard already set */
761 if (nextlen == 0) max_count = 138, min_count = 3;
762
763 for (n = 0; n <= max_code; n++) {
764 curlen = nextlen; nextlen = tree[n + 1].Len;
765 if (++count < max_count && curlen == nextlen) {
766 continue;
767 } else if (count < min_count) {
768 do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
769
770 } else if (curlen != 0) {
771 if (curlen != prevlen) {
772 send_code(s, curlen, s->bl_tree); count--;
773 }
774 Assert(count >= 3 && count <= 6, " 3_6?");
775 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count - 3, 2);
776
777 } else if (count <= 10) {
778 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count - 3, 3);
779
780 } else {
781 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count - 11, 7);
782 }
783 count = 0; prevlen = curlen;
784 if (nextlen == 0) {
785 max_count = 138, min_count = 3;
786 } else if (curlen == nextlen) {
787 max_count = 6, min_count = 3;
788 } else {
789 max_count = 7, min_count = 4;
790 }
791 }
792 }
793
794 /* ===========================================================================
795 * Construct the Huffman tree for the bit lengths and return the index in
796 * bl_order of the last bit length code to send.
797 */
798 local int build_bl_tree(deflate_state *s) {
799 int max_blindex; /* index of last bit length code of non zero freq */
800
801 /* Determine the bit length frequencies for literal and distance trees */
802 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
803 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
804
805 /* Build the bit length tree: */
806 build_tree(s, (tree_desc *)(&(s->bl_desc)));
807 /* opt_len now includes the length of the tree representations, except the
808 * lengths of the bit lengths codes and the 5 + 5 + 4 bits for the counts.
809 */
810
811 /* Determine the number of bit length codes to send. The pkzip format
812 * requires that at least 4 bit length codes be sent. (appnote.txt says
813 * 3 but the actual value used is 4.)
814 */
815 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
816 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
817 }
818 /* Update opt_len to include the bit length tree and counts */
819 s->opt_len += 3*((ulg)max_blindex + 1) + 5 + 5 + 4;
820 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
821 s->opt_len, s->static_len));
822
823 return max_blindex;
824 }
825
826 /* ===========================================================================
827 * Send the header for a block using dynamic Huffman trees: the counts, the
828 * lengths of the bit length codes, the literal tree and the distance tree.
829 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
830 */
831 local void send_all_trees(deflate_state *s, int lcodes, int dcodes,
832 int blcodes) {
833 int rank; /* index in bl_order */
834
835 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
836 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
837 "too many codes");
838 Tracev((stderr, "\nbl counts: "));
839 send_bits(s, lcodes - 257, 5); /* not +255 as stated in appnote.txt */
840 send_bits(s, dcodes - 1, 5);
841 send_bits(s, blcodes - 4, 4); /* not -3 as stated in appnote.txt */
842 for (rank = 0; rank < blcodes; rank++) {
843 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
844 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
845 }
846 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
847
848 send_tree(s, (ct_data *)s->dyn_ltree, lcodes - 1); /* literal tree */
849 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
850
851 send_tree(s, (ct_data *)s->dyn_dtree, dcodes - 1); /* distance tree */
852 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
853 }
854
855 /* ===========================================================================
856 * Send a stored block
857 */
858 void ZLIB_INTERNAL _tr_stored_block(deflate_state *s, charf *buf,
859 ulg stored_len, int last) {
860 send_bits(s, (STORED_BLOCK<<1) + last, 3); /* send block type */
861 bi_windup(s); /* align on byte boundary */
862 put_short(s, (ush)stored_len);
863 put_short(s, (ush)~stored_len);
864 if (stored_len)
865 zmemcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len);
866 s->pending += stored_len;
867 #ifdef ZLIB_DEBUG
868 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
869 s->compressed_len += (stored_len + 4) << 3;
870 s->bits_sent += 2*16;
871 s->bits_sent += stored_len << 3;
872 #endif
873 }
874
875 /* ===========================================================================
876 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
877 */
878 void ZLIB_INTERNAL _tr_flush_bits(deflate_state *s) {
879 bi_flush(s);
880 }
881
882 /* ===========================================================================
883 * Send one empty static block to give enough lookahead for inflate.
884 * This takes 10 bits, of which 7 may remain in the bit buffer.
885 */
886 void ZLIB_INTERNAL _tr_align(deflate_state *s) {
887 send_bits(s, STATIC_TREES<<1, 3);
888 send_code(s, END_BLOCK, static_ltree);
889 #ifdef ZLIB_DEBUG
890 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
891 #endif
892 bi_flush(s);
893 }
894
895 /* ===========================================================================
896 * Send the block data compressed using the given Huffman trees
897 */
898 local void compress_block(deflate_state *s, const ct_data *ltree,
899 const ct_data *dtree) {
900 unsigned dist; /* distance of matched string */
901 int lc; /* match length or unmatched char (if dist == 0) */
902 unsigned sx = 0; /* running index in symbol buffers */
903 unsigned code; /* the code to send */
904 int extra; /* number of extra bits to send */
905
906 if (s->sym_next != 0) do {
907 #ifdef LIT_MEM
908 dist = s->d_buf[sx];
909 lc = s->l_buf[sx++];
910 #else
911 dist = s->sym_buf[sx++] & 0xff;
912 dist += (unsigned)(s->sym_buf[sx++] & 0xff) << 8;
913 lc = s->sym_buf[sx++];
914 #endif
915 if (dist == 0) {
916 send_code(s, lc, ltree); /* send a literal byte */
917 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
918 } else {
919 /* Here, lc is the match length - MIN_MATCH */
920 code = _length_code[lc];
921 send_code(s, code + LITERALS + 1, ltree); /* send length code */
922 extra = extra_lbits[code];
923 if (extra != 0) {
924 lc -= base_length[code];
925 send_bits(s, lc, extra); /* send the extra length bits */
926 }
927 dist--; /* dist is now the match distance - 1 */
928 code = d_code(dist);
929 Assert (code < D_CODES, "bad d_code");
930
931 send_code(s, code, dtree); /* send the distance code */
932 extra = extra_dbits[code];
933 if (extra != 0) {
934 dist -= (unsigned)base_dist[code];
935 send_bits(s, dist, extra); /* send the extra distance bits */
936 }
937 } /* literal or match pair ? */
938
939 /* Check for no overlay of pending_buf on needed symbols */
940 #ifdef LIT_MEM
941 Assert(s->pending < 2 * (s->lit_bufsize + sx), "pendingBuf overflow");
942 #else
943 Assert(s->pending < s->lit_bufsize + sx, "pendingBuf overflow");
944 #endif
945
946 } while (sx < s->sym_next);
947
948 send_code(s, END_BLOCK, ltree);
949 }
950
951 /* ===========================================================================
952 * Check if the data type is TEXT or BINARY, using the following algorithm:
953 * - TEXT if the two conditions below are satisfied:
954 * a) There are no non-portable control characters belonging to the
955 * "block list" (0..6, 14..25, 28..31).
956 * b) There is at least one printable character belonging to the
957 * "allow list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
958 * - BINARY otherwise.
959 * - The following partially-portable control characters form a
960 * "gray list" that is ignored in this detection algorithm:
961 * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
962 * IN assertion: the fields Freq of dyn_ltree are set.
963 */
964 local int detect_data_type(deflate_state *s) {
965 /* block_mask is the bit mask of block-listed bytes
966 * set bits 0..6, 14..25, and 28..31
967 * 0xf3ffc07f = binary 11110011111111111100000001111111
968 */
969 unsigned long block_mask = 0xf3ffc07fUL;
970 int n;
971
972 /* Check for non-textual ("block-listed") bytes. */
973 for (n = 0; n <= 31; n++, block_mask >>= 1)
974 if ((block_mask & 1) && (s->dyn_ltree[n].Freq != 0))
975 return Z_BINARY;
976
977 /* Check for textual ("allow-listed") bytes. */
978 if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
979 || s->dyn_ltree[13].Freq != 0)
980 return Z_TEXT;
981 for (n = 32; n < LITERALS; n++)
982 if (s->dyn_ltree[n].Freq != 0)
983 return Z_TEXT;
984
985 /* There are no "block-listed" or "allow-listed" bytes:
986 * this stream either is empty or has tolerated ("gray-listed") bytes only.
987 */
988 return Z_BINARY;
989 }
990
991 /* ===========================================================================
992 * Determine the best encoding for the current block: dynamic trees, static
993 * trees or store, and write out the encoded block.
994 */
995 void ZLIB_INTERNAL _tr_flush_block(deflate_state *s, charf *buf,
996 ulg stored_len, int last) {
997 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
998 int max_blindex = 0; /* index of last bit length code of non zero freq */
999
1000 /* Build the Huffman trees unless a stored block is forced */
1001 if (s->level > 0) {
1002
1003 /* Check if the file is binary or text */
1004 if (s->strm->data_type == Z_UNKNOWN)
1005 s->strm->data_type = detect_data_type(s);
1006
1007 /* Construct the literal and distance trees */
1008 build_tree(s, (tree_desc *)(&(s->l_desc)));
1009 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
1010 s->static_len));
1011
1012 build_tree(s, (tree_desc *)(&(s->d_desc)));
1013 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
1014 s->static_len));
1015 /* At this point, opt_len and static_len are the total bit lengths of
1016 * the compressed block data, excluding the tree representations.
1017 */
1018
1019 /* Build the bit length tree for the above two trees, and get the index
1020 * in bl_order of the last bit length code to send.
1021 */
1022 max_blindex = build_bl_tree(s);
1023
1024 /* Determine the best encoding. Compute the block lengths in bytes. */
1025 opt_lenb = (s->opt_len + 3 + 7) >> 3;
1026 static_lenb = (s->static_len + 3 + 7) >> 3;
1027
1028 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
1029 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
1030 s->sym_next / 3));
1031
1032 #ifndef FORCE_STATIC
1033 if (static_lenb <= opt_lenb || s->strategy == Z_FIXED)
1034 #endif
1035 opt_lenb = static_lenb;
1036
1037 } else {
1038 Assert(buf != (char*)0, "lost buf");
1039 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
1040 }
1041
1042 #ifdef FORCE_STORED
1043 if (buf != (char*)0) { /* force stored block */
1044 #else
1045 if (stored_len + 4 <= opt_lenb && buf != (char*)0) {
1046 /* 4: two words for the lengths */
1047 #endif
1048 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1049 * Otherwise we can't have processed more than WSIZE input bytes since
1050 * the last block flush, because compression would have been
1051 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1052 * transform a block into a stored block.
1053 */
1054 _tr_stored_block(s, buf, stored_len, last);
1055
1056 } else if (static_lenb == opt_lenb) {
1057 send_bits(s, (STATIC_TREES<<1) + last, 3);
1058 compress_block(s, (const ct_data *)static_ltree,
1059 (const ct_data *)static_dtree);
1060 #ifdef ZLIB_DEBUG
1061 s->compressed_len += 3 + s->static_len;
1062 #endif
1063 } else {
1064 send_bits(s, (DYN_TREES<<1) + last, 3);
1065 send_all_trees(s, s->l_desc.max_code + 1, s->d_desc.max_code + 1,
1066 max_blindex + 1);
1067 compress_block(s, (const ct_data *)s->dyn_ltree,
1068 (const ct_data *)s->dyn_dtree);
1069 #ifdef ZLIB_DEBUG
1070 s->compressed_len += 3 + s->opt_len;
1071 #endif
1072 }
1073 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1074 /* The above check is made mod 2^32, for files larger than 512 MB
1075 * and uLong implemented on 32 bits.
1076 */
1077 init_block(s);
1078
1079 if (last) {
1080 bi_windup(s);
1081 #ifdef ZLIB_DEBUG
1082 s->compressed_len += 7; /* align on byte boundary */
1083 #endif
1084 }
1085 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len >> 3,
1086 s->compressed_len - 7*last));
1087 }
1088
1089 /* ===========================================================================
1090 * Save the match info and tally the frequency counts. Return true if
1091 * the current block must be flushed.
1092 */
1093 int ZLIB_INTERNAL _tr_tally(deflate_state *s, unsigned dist, unsigned lc) {
1094 #ifdef LIT_MEM
1095 s->d_buf[s->sym_next] = (ush)dist;
1096 s->l_buf[s->sym_next++] = (uch)lc;
1097 #else
1098 s->sym_buf[s->sym_next++] = (uch)dist;
1099 s->sym_buf[s->sym_next++] = (uch)(dist >> 8);
1100 s->sym_buf[s->sym_next++] = (uch)lc;
1101 #endif
1102 if (dist == 0) {
1103 /* lc is the unmatched char */
1104 s->dyn_ltree[lc].Freq++;
1105 } else {
1106 s->matches++;
1107 /* Here, lc is the match length - MIN_MATCH */
1108 dist--; /* dist = match distance - 1 */
1109 Assert((ush)dist < (ush)MAX_DIST(s) &&
1110 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1111 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1112
1113 s->dyn_ltree[_length_code[lc] + LITERALS + 1].Freq++;
1114 s->dyn_dtree[d_code(dist)].Freq++;
1115 }
1116 return (s->sym_next == s->sym_end);
1117 }