Line data Source code
1 : /* trees.c -- output deflated data using Huffman coding
2 : * Copyright (C) 1995-2017 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 : local const static_tree_desc static_l_desc =
126 : {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
127 :
128 : local const static_tree_desc static_d_desc =
129 : {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
130 :
131 : local const 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 :
156 : #ifdef GEN_TREES_H
157 : local void gen_trees_header OF((void));
158 : #endif
159 :
160 : #ifndef ZLIB_DEBUG
161 : # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
162 : /* Send a code of the given tree. c and tree must not have side effects */
163 :
164 : #else /* !ZLIB_DEBUG */
165 : # define send_code(s, c, tree) \
166 : { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
167 : send_bits(s, tree[c].Code, tree[c].Len); }
168 : #endif
169 :
170 : /* ===========================================================================
171 : * Output a short LSB first on the stream.
172 : * IN assertion: there is enough room in pendingBuf.
173 : */
174 : #define put_short(s, w) { \
175 : put_byte(s, (uch)((w) & 0xff)); \
176 : put_byte(s, (uch)((ush)(w) >> 8)); \
177 : }
178 :
179 : /* ===========================================================================
180 : * Send a value on a given number of bits.
181 : * IN assertion: length <= 16 and value fits in length bits.
182 : */
183 : #ifdef ZLIB_DEBUG
184 : local void send_bits OF((deflate_state *s, int value, int length));
185 :
186 : local void send_bits(s, value, length)
187 : deflate_state *s;
188 : int value; /* value to send */
189 : int length; /* number of bits */
190 : {
191 : Tracevv((stderr," l %2d v %4x ", length, value));
192 : Assert(length > 0 && length <= 15, "invalid length");
193 : s->bits_sent += (ulg)length;
194 :
195 : /* If not enough room in bi_buf, use (valid) bits from bi_buf and
196 : * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
197 : * unused bits in value.
198 : */
199 : if (s->bi_valid > (int)Buf_size - length) {
200 : s->bi_buf |= (ush)value << s->bi_valid;
201 : put_short(s, s->bi_buf);
202 : s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
203 : s->bi_valid += length - Buf_size;
204 : } else {
205 : s->bi_buf |= (ush)value << s->bi_valid;
206 : s->bi_valid += length;
207 : }
208 : }
209 : #else /* !ZLIB_DEBUG */
210 :
211 : #define send_bits(s, value, length) \
212 : { int len = length;\
213 : if (s->bi_valid > (int)Buf_size - len) {\
214 : int val = (int)value;\
215 : s->bi_buf |= (ush)val << s->bi_valid;\
216 : put_short(s, s->bi_buf);\
217 : s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
218 : s->bi_valid += len - Buf_size;\
219 : } else {\
220 : s->bi_buf |= (ush)(value) << s->bi_valid;\
221 : s->bi_valid += len;\
222 : }\
223 : }
224 : #endif /* ZLIB_DEBUG */
225 :
226 :
227 : /* the arguments must not have side effects */
228 :
229 : /* ===========================================================================
230 : * Initialize the various 'constant' tables.
231 : */
232 72 : local void tr_static_init()
233 : {
234 : #if defined(GEN_TREES_H) || !defined(STDC)
235 : static int static_init_done = 0;
236 : int n; /* iterates over tree elements */
237 : int bits; /* bit counter */
238 : int length; /* length value */
239 : int code; /* code value */
240 : int dist; /* distance index */
241 : ush bl_count[MAX_BITS+1];
242 : /* number of codes at each bit length for an optimal tree */
243 :
244 : if (static_init_done) return;
245 :
246 : /* For some embedded targets, global variables are not initialized: */
247 : #ifdef NO_INIT_GLOBAL_POINTERS
248 : static_l_desc.static_tree = static_ltree;
249 : static_l_desc.extra_bits = extra_lbits;
250 : static_d_desc.static_tree = static_dtree;
251 : static_d_desc.extra_bits = extra_dbits;
252 : static_bl_desc.extra_bits = extra_blbits;
253 : #endif
254 :
255 : /* Initialize the mapping length (0..255) -> length code (0..28) */
256 : length = 0;
257 : for (code = 0; code < LENGTH_CODES-1; code++) {
258 : base_length[code] = length;
259 : for (n = 0; n < (1<<extra_lbits[code]); n++) {
260 : _length_code[length++] = (uch)code;
261 : }
262 : }
263 : Assert (length == 256, "tr_static_init: length != 256");
264 : /* Note that the length 255 (match length 258) can be represented
265 : * in two different ways: code 284 + 5 bits or code 285, so we
266 : * overwrite length_code[255] to use the best encoding:
267 : */
268 : _length_code[length-1] = (uch)code;
269 :
270 : /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
271 : dist = 0;
272 : for (code = 0 ; code < 16; code++) {
273 : base_dist[code] = dist;
274 : for (n = 0; n < (1<<extra_dbits[code]); n++) {
275 : _dist_code[dist++] = (uch)code;
276 : }
277 : }
278 : Assert (dist == 256, "tr_static_init: dist != 256");
279 : dist >>= 7; /* from now on, all distances are divided by 128 */
280 : for ( ; code < D_CODES; code++) {
281 : base_dist[code] = dist << 7;
282 : for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
283 : _dist_code[256 + dist++] = (uch)code;
284 : }
285 : }
286 : Assert (dist == 256, "tr_static_init: 256+dist != 512");
287 :
288 : /* Construct the codes of the static literal tree */
289 : for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
290 : n = 0;
291 : while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
292 : while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
293 : while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
294 : while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
295 : /* Codes 286 and 287 do not exist, but we must include them in the
296 : * tree construction to get a canonical Huffman tree (longest code
297 : * all ones)
298 : */
299 : gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
300 :
301 : /* The static distance tree is trivial: */
302 : for (n = 0; n < D_CODES; n++) {
303 : static_dtree[n].Len = 5;
304 : static_dtree[n].Code = bi_reverse((unsigned)n, 5);
305 : }
306 : static_init_done = 1;
307 :
308 : # ifdef GEN_TREES_H
309 : gen_trees_header();
310 : # endif
311 : #endif /* defined(GEN_TREES_H) || !defined(STDC) */
312 72 : }
313 :
314 : /* ===========================================================================
315 : * Genererate the file trees.h describing the static trees.
316 : */
317 : #ifdef GEN_TREES_H
318 : # ifndef ZLIB_DEBUG
319 : # include <stdio.h>
320 : # endif
321 :
322 : # define SEPARATOR(i, last, width) \
323 : ((i) == (last)? "\n};\n\n" : \
324 : ((i) % (width) == (width)-1 ? ",\n" : ", "))
325 :
326 : void gen_trees_header()
327 : {
328 : FILE *header = fopen("trees.h", "w");
329 : int i;
330 :
331 : Assert (header != NULL, "Can't open trees.h");
332 : fprintf(header,
333 : "/* header created automatically with -DGEN_TREES_H */\n\n");
334 :
335 : fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
336 : for (i = 0; i < L_CODES+2; i++) {
337 : fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
338 : static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
339 : }
340 :
341 : fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
342 : for (i = 0; i < D_CODES; i++) {
343 : fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
344 : static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
345 : }
346 :
347 : fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
348 : for (i = 0; i < DIST_CODE_LEN; i++) {
349 : fprintf(header, "%2u%s", _dist_code[i],
350 : SEPARATOR(i, DIST_CODE_LEN-1, 20));
351 : }
352 :
353 : fprintf(header,
354 : "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
355 : for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
356 : fprintf(header, "%2u%s", _length_code[i],
357 : SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
358 : }
359 :
360 : fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
361 : for (i = 0; i < LENGTH_CODES; i++) {
362 : fprintf(header, "%1u%s", base_length[i],
363 : SEPARATOR(i, LENGTH_CODES-1, 20));
364 : }
365 :
366 : fprintf(header, "local const int base_dist[D_CODES] = {\n");
367 : for (i = 0; i < D_CODES; i++) {
368 : fprintf(header, "%5u%s", base_dist[i],
369 : SEPARATOR(i, D_CODES-1, 10));
370 : }
371 :
372 : fclose(header);
373 : }
374 : #endif /* GEN_TREES_H */
375 :
376 : /* ===========================================================================
377 : * Initialize the tree data structures for a new zlib stream.
378 : */
379 72 : void ZLIB_INTERNAL _tr_init(s)
380 : deflate_state *s;
381 : {
382 72 : tr_static_init();
383 :
384 72 : s->l_desc.dyn_tree = s->dyn_ltree;
385 72 : s->l_desc.stat_desc = &static_l_desc;
386 :
387 72 : s->d_desc.dyn_tree = s->dyn_dtree;
388 72 : s->d_desc.stat_desc = &static_d_desc;
389 :
390 72 : s->bl_desc.dyn_tree = s->bl_tree;
391 72 : s->bl_desc.stat_desc = &static_bl_desc;
392 :
393 72 : s->bi_buf = 0;
394 72 : s->bi_valid = 0;
395 : #ifdef ZLIB_DEBUG
396 : s->compressed_len = 0L;
397 : s->bits_sent = 0L;
398 : #endif
399 :
400 : /* Initialize the first block of the first file: */
401 72 : init_block(s);
402 72 : }
403 :
404 : /* ===========================================================================
405 : * Initialize a new block.
406 : */
407 144 : local void init_block(s)
408 : deflate_state *s;
409 : {
410 : int n; /* iterates over tree elements */
411 :
412 : /* Initialize the trees. */
413 144 : for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
414 144 : for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
415 144 : for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
416 :
417 144 : s->dyn_ltree[END_BLOCK].Freq = 1;
418 144 : s->opt_len = s->static_len = 0L;
419 144 : s->last_lit = s->matches = 0;
420 144 : }
421 :
422 : #define SMALLEST 1
423 : /* Index within the heap array of least frequent node in the Huffman tree */
424 :
425 :
426 : /* ===========================================================================
427 : * Remove the smallest element from the heap and recreate the heap with
428 : * one less element. Updates heap and heap_len.
429 : */
430 : #define pqremove(s, tree, top) \
431 : {\
432 : top = s->heap[SMALLEST]; \
433 : s->heap[SMALLEST] = s->heap[s->heap_len--]; \
434 : pqdownheap(s, tree, SMALLEST); \
435 : }
436 :
437 : /* ===========================================================================
438 : * Compares to subtrees, using the tree depth as tie breaker when
439 : * the subtrees have equal frequency. This minimizes the worst case length.
440 : */
441 : #define smaller(tree, n, m, depth) \
442 : (tree[n].Freq < tree[m].Freq || \
443 : (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
444 :
445 : /* ===========================================================================
446 : * Restore the heap property by moving down the tree starting at node k,
447 : * exchanging a node with the smallest of its two sons if necessary, stopping
448 : * when the heap property is re-established (each father smaller than its
449 : * two sons).
450 : */
451 648 : local void pqdownheap(s, tree, k)
452 : deflate_state *s;
453 : ct_data *tree; /* the tree to restore */
454 : int k; /* node to move down */
455 : {
456 648 : int v = s->heap[k];
457 648 : int j = k << 1; /* left son of k */
458 1368 : while (j <= s->heap_len) {
459 : /* Set j to the smallest of the two sons: */
460 216 : if (j < s->heap_len &&
461 0 : smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
462 0 : j++;
463 : }
464 : /* Exit if v is smaller than both sons */
465 216 : if (smaller(tree, v, s->heap[j], s->depth)) break;
466 :
467 : /* Exchange v with the smallest son */
468 72 : s->heap[k] = s->heap[j]; k = j;
469 :
470 : /* And continue down the tree, setting j to the left son of k */
471 72 : j <<= 1;
472 : }
473 648 : s->heap[k] = v;
474 648 : }
475 :
476 : /* ===========================================================================
477 : * Compute the optimal bit lengths for a tree and update the total bit length
478 : * for the current block.
479 : * IN assertion: the fields freq and dad are set, heap[heap_max] and
480 : * above are the tree nodes sorted by increasing frequency.
481 : * OUT assertions: the field len is set to the optimal bit length, the
482 : * array bl_count contains the frequencies for each bit length.
483 : * The length opt_len is updated; static_len is also updated if stree is
484 : * not null.
485 : */
486 216 : local void gen_bitlen(s, desc)
487 : deflate_state *s;
488 : tree_desc *desc; /* the tree descriptor */
489 : {
490 216 : ct_data *tree = desc->dyn_tree;
491 216 : int max_code = desc->max_code;
492 216 : const ct_data *stree = desc->stat_desc->static_tree;
493 216 : const intf *extra = desc->stat_desc->extra_bits;
494 216 : int base = desc->stat_desc->extra_base;
495 216 : int max_length = desc->stat_desc->max_length;
496 : int h; /* heap index */
497 : int n, m; /* iterate over the tree elements */
498 : int bits; /* bit length */
499 : int xbits; /* extra bits */
500 : ush f; /* frequency */
501 216 : int overflow = 0; /* number of elements with bit length too large */
502 :
503 216 : for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
504 :
505 : /* In a first pass, compute the optimal bit lengths (which may
506 : * overflow in the case of the bit length tree).
507 : */
508 216 : tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
509 :
510 648 : for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
511 432 : n = s->heap[h];
512 432 : bits = tree[tree[n].Dad].Len + 1;
513 432 : if (bits > max_length) bits = max_length, overflow++;
514 432 : tree[n].Len = (ush)bits;
515 : /* We overwrite tree[n].Dad which is no longer needed */
516 :
517 432 : if (n > max_code) continue; /* not a leaf node */
518 :
519 432 : s->bl_count[bits]++;
520 432 : xbits = 0;
521 432 : if (n >= base) xbits = extra[n-base];
522 432 : f = tree[n].Freq;
523 432 : s->opt_len += (ulg)f * (unsigned)(bits + xbits);
524 432 : if (stree) s->static_len += (ulg)f * (unsigned)(stree[n].Len + xbits);
525 : }
526 216 : if (overflow == 0) return;
527 :
528 : Tracev((stderr,"\nbit length overflow\n"));
529 : /* This happens for example on obj2 and pic of the Calgary corpus */
530 :
531 : /* Find the first bit length which could increase: */
532 : do {
533 0 : bits = max_length-1;
534 0 : while (s->bl_count[bits] == 0) bits--;
535 0 : s->bl_count[bits]--; /* move one leaf down the tree */
536 0 : s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
537 0 : s->bl_count[max_length]--;
538 : /* The brother of the overflow item also moves one step up,
539 : * but this does not affect bl_count[max_length]
540 : */
541 0 : overflow -= 2;
542 0 : } while (overflow > 0);
543 :
544 : /* Now recompute all bit lengths, scanning in increasing frequency.
545 : * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
546 : * lengths instead of fixing only the wrong ones. This idea is taken
547 : * from 'ar' written by Haruhiko Okumura.)
548 : */
549 0 : for (bits = max_length; bits != 0; bits--) {
550 0 : n = s->bl_count[bits];
551 0 : while (n != 0) {
552 0 : m = s->heap[--h];
553 0 : if (m > max_code) continue;
554 0 : if ((unsigned) tree[m].Len != (unsigned) bits) {
555 : Tracev((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
556 0 : s->opt_len += ((ulg)bits - tree[m].Len) * tree[m].Freq;
557 0 : tree[m].Len = (ush)bits;
558 : }
559 0 : n--;
560 : }
561 : }
562 : }
563 :
564 : /* ===========================================================================
565 : * Generate the codes for a given tree and bit counts (which need not be
566 : * optimal).
567 : * IN assertion: the array bl_count contains the bit length statistics for
568 : * the given tree and the field len is set for all tree elements.
569 : * OUT assertion: the field code is set for all tree elements of non
570 : * zero code length.
571 : */
572 216 : local void gen_codes (tree, max_code, bl_count)
573 : ct_data *tree; /* the tree to decorate */
574 : int max_code; /* largest code with non zero frequency */
575 : ushf *bl_count; /* number of codes at each bit length */
576 : {
577 : ush next_code[MAX_BITS+1]; /* next code value for each bit length */
578 216 : unsigned code = 0; /* running code value */
579 : int bits; /* bit index */
580 : int n; /* code index */
581 :
582 : /* The distribution counts are first used to generate the code values
583 : * without bit reversal.
584 : */
585 3456 : for (bits = 1; bits <= MAX_BITS; bits++) {
586 3240 : code = (code + bl_count[bits-1]) << 1;
587 3240 : next_code[bits] = (ush)code;
588 : }
589 : /* Check that the bit counts in bl_count are consistent. The last code
590 : * must be all ones.
591 : */
592 : Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
593 : "inconsistent bit counts");
594 : Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
595 :
596 20232 : for (n = 0; n <= max_code; n++) {
597 20016 : int len = tree[n].Len;
598 20016 : if (len == 0) continue;
599 : /* Now reverse the bits */
600 432 : tree[n].Code = (ush)bi_reverse(next_code[len]++, len);
601 :
602 : Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
603 : n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
604 : }
605 216 : }
606 :
607 : /* ===========================================================================
608 : * Construct one Huffman tree and assigns the code bit strings and lengths.
609 : * Update the total bit length for the current block.
610 : * IN assertion: the field freq is set for all tree elements.
611 : * OUT assertions: the fields len and code are set to the optimal bit length
612 : * and corresponding code. The length opt_len is updated; static_len is
613 : * also updated if stree is not null. The field max_code is set.
614 : */
615 216 : local void build_tree(s, desc)
616 : deflate_state *s;
617 : tree_desc *desc; /* the tree descriptor */
618 : {
619 216 : ct_data *tree = desc->dyn_tree;
620 216 : const ct_data *stree = desc->stat_desc->static_tree;
621 216 : int elems = desc->stat_desc->elems;
622 : int n, m; /* iterate over heap elements */
623 216 : int max_code = -1; /* largest code with non zero frequency */
624 : int node; /* new node being created */
625 :
626 : /* Construct the initial heap, with least frequent element in
627 : * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
628 : * heap[0] is not used.
629 : */
630 216 : s->heap_len = 0, s->heap_max = HEAP_SIZE;
631 :
632 24336 : for (n = 0; n < elems; n++) {
633 24120 : if (tree[n].Freq != 0) {
634 216 : s->heap[++(s->heap_len)] = max_code = n;
635 216 : s->depth[n] = 0;
636 : } else {
637 23904 : tree[n].Len = 0;
638 : }
639 : }
640 :
641 : /* The pkzip format requires that at least one distance code exists,
642 : * and that at least one bit should be sent even if there is only one
643 : * possible code. So to avoid special checks later on we force at least
644 : * two codes of non zero frequency.
645 : */
646 648 : while (s->heap_len < 2) {
647 216 : node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
648 216 : tree[node].Freq = 1;
649 216 : s->depth[node] = 0;
650 216 : s->opt_len--; if (stree) s->static_len -= stree[node].Len;
651 : /* node is 0 or 1 so it does not have extra bits */
652 : }
653 216 : desc->max_code = max_code;
654 :
655 : /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
656 : * establish sub-heaps of increasing lengths:
657 : */
658 216 : for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
659 :
660 : /* Construct the Huffman tree by repeatedly combining the least two
661 : * frequent nodes.
662 : */
663 216 : node = elems; /* next internal node of the tree */
664 : do {
665 216 : pqremove(s, tree, n); /* n = node of least frequency */
666 216 : m = s->heap[SMALLEST]; /* m = node of next least frequency */
667 :
668 216 : s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
669 216 : s->heap[--(s->heap_max)] = m;
670 :
671 : /* Create a new node father of n and m */
672 216 : tree[node].Freq = tree[n].Freq + tree[m].Freq;
673 432 : s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
674 216 : s->depth[n] : s->depth[m]) + 1);
675 216 : tree[n].Dad = tree[m].Dad = (ush)node;
676 : #ifdef DUMP_BL_TREE
677 : if (tree == s->bl_tree) {
678 : fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
679 : node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
680 : }
681 : #endif
682 : /* and insert the new node in the heap */
683 216 : s->heap[SMALLEST] = node++;
684 216 : pqdownheap(s, tree, SMALLEST);
685 :
686 216 : } while (s->heap_len >= 2);
687 :
688 216 : s->heap[--(s->heap_max)] = s->heap[SMALLEST];
689 :
690 : /* At this point, the fields freq and dad are set. We can now
691 : * generate the bit lengths.
692 : */
693 216 : gen_bitlen(s, (tree_desc *)desc);
694 :
695 : /* The field len is now set, we can generate the bit codes */
696 216 : gen_codes ((ct_data *)tree, max_code, s->bl_count);
697 216 : }
698 :
699 : /* ===========================================================================
700 : * Scan a literal or distance tree to determine the frequencies of the codes
701 : * in the bit length tree.
702 : */
703 144 : local void scan_tree (s, tree, max_code)
704 : deflate_state *s;
705 : ct_data *tree; /* the tree to be scanned */
706 : int max_code; /* and its largest code of non zero frequency */
707 : {
708 : int n; /* iterates over all tree elements */
709 144 : int prevlen = -1; /* last emitted length */
710 : int curlen; /* length of current code */
711 144 : int nextlen = tree[0].Len; /* length of next code */
712 144 : int count = 0; /* repeat count of the current code */
713 144 : int max_count = 7; /* max repeat count */
714 144 : int min_count = 4; /* min repeat count */
715 :
716 144 : if (nextlen == 0) max_count = 138, min_count = 3;
717 144 : tree[max_code+1].Len = (ush)0xffff; /* guard */
718 :
719 18792 : for (n = 0; n <= max_code; n++) {
720 18648 : curlen = nextlen; nextlen = tree[n+1].Len;
721 18648 : if (++count < max_count && curlen == nextlen) {
722 18288 : continue;
723 360 : } else if (count < min_count) {
724 216 : s->bl_tree[curlen].Freq += count;
725 144 : } else if (curlen != 0) {
726 0 : if (curlen != prevlen) s->bl_tree[curlen].Freq++;
727 0 : s->bl_tree[REP_3_6].Freq++;
728 144 : } else if (count <= 10) {
729 0 : s->bl_tree[REPZ_3_10].Freq++;
730 : } else {
731 144 : s->bl_tree[REPZ_11_138].Freq++;
732 : }
733 360 : count = 0; prevlen = curlen;
734 360 : if (nextlen == 0) {
735 144 : max_count = 138, min_count = 3;
736 216 : } else if (curlen == nextlen) {
737 0 : max_count = 6, min_count = 3;
738 : } else {
739 216 : max_count = 7, min_count = 4;
740 : }
741 : }
742 144 : }
743 :
744 : /* ===========================================================================
745 : * Send a literal or distance tree in compressed form, using the codes in
746 : * bl_tree.
747 : */
748 0 : local void send_tree (s, tree, max_code)
749 : deflate_state *s;
750 : ct_data *tree; /* the tree to be scanned */
751 : int max_code; /* and its largest code of non zero frequency */
752 : {
753 : int n; /* iterates over all tree elements */
754 0 : int prevlen = -1; /* last emitted length */
755 : int curlen; /* length of current code */
756 0 : int nextlen = tree[0].Len; /* length of next code */
757 0 : int count = 0; /* repeat count of the current code */
758 0 : int max_count = 7; /* max repeat count */
759 0 : int min_count = 4; /* min repeat count */
760 :
761 : /* tree[max_code+1].Len = -1; */ /* guard already set */
762 0 : if (nextlen == 0) max_count = 138, min_count = 3;
763 :
764 0 : for (n = 0; n <= max_code; n++) {
765 0 : curlen = nextlen; nextlen = tree[n+1].Len;
766 0 : if (++count < max_count && curlen == nextlen) {
767 0 : continue;
768 0 : } else if (count < min_count) {
769 0 : do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
770 :
771 0 : } else if (curlen != 0) {
772 0 : if (curlen != prevlen) {
773 0 : send_code(s, curlen, s->bl_tree); count--;
774 : }
775 : Assert(count >= 3 && count <= 6, " 3_6?");
776 0 : send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
777 :
778 0 : } else if (count <= 10) {
779 0 : send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
780 :
781 : } else {
782 0 : send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
783 : }
784 0 : count = 0; prevlen = curlen;
785 0 : if (nextlen == 0) {
786 0 : max_count = 138, min_count = 3;
787 0 : } else if (curlen == nextlen) {
788 0 : max_count = 6, min_count = 3;
789 : } else {
790 0 : max_count = 7, min_count = 4;
791 : }
792 : }
793 0 : }
794 :
795 : /* ===========================================================================
796 : * Construct the Huffman tree for the bit lengths and return the index in
797 : * bl_order of the last bit length code to send.
798 : */
799 72 : local int build_bl_tree(s)
800 : deflate_state *s;
801 : {
802 : int max_blindex; /* index of last bit length code of non zero freq */
803 :
804 : /* Determine the bit length frequencies for literal and distance trees */
805 72 : scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
806 72 : scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
807 :
808 : /* Build the bit length tree: */
809 72 : build_tree(s, (tree_desc *)(&(s->bl_desc)));
810 : /* opt_len now includes the length of the tree representations, except
811 : * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
812 : */
813 :
814 : /* Determine the number of bit length codes to send. The pkzip format
815 : * requires that at least 4 bit length codes be sent. (appnote.txt says
816 : * 3 but the actual value used is 4.)
817 : */
818 144 : for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
819 144 : if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
820 : }
821 : /* Update opt_len to include the bit length tree and counts */
822 72 : s->opt_len += 3*((ulg)max_blindex+1) + 5+5+4;
823 : Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
824 : s->opt_len, s->static_len));
825 :
826 72 : return max_blindex;
827 : }
828 :
829 : /* ===========================================================================
830 : * Send the header for a block using dynamic Huffman trees: the counts, the
831 : * lengths of the bit length codes, the literal tree and the distance tree.
832 : * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
833 : */
834 0 : local void send_all_trees(s, lcodes, dcodes, blcodes)
835 : deflate_state *s;
836 : int lcodes, dcodes, blcodes; /* number of codes for each tree */
837 : {
838 : int rank; /* index in bl_order */
839 :
840 : Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
841 : Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
842 : "too many codes");
843 : Tracev((stderr, "\nbl counts: "));
844 0 : send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
845 0 : send_bits(s, dcodes-1, 5);
846 0 : send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
847 0 : for (rank = 0; rank < blcodes; rank++) {
848 : Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
849 0 : send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
850 : }
851 : Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
852 :
853 0 : send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
854 : Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
855 :
856 0 : send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
857 : Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
858 0 : }
859 :
860 : /* ===========================================================================
861 : * Send a stored block
862 : */
863 0 : void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
864 : deflate_state *s;
865 : charf *buf; /* input block */
866 : ulg stored_len; /* length of input block */
867 : int last; /* one if this is the last block for a file */
868 : {
869 0 : send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */
870 0 : bi_windup(s); /* align on byte boundary */
871 0 : put_short(s, (ush)stored_len);
872 0 : put_short(s, (ush)~stored_len);
873 0 : zmemcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len);
874 0 : s->pending += stored_len;
875 : #ifdef ZLIB_DEBUG
876 : s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
877 : s->compressed_len += (stored_len + 4) << 3;
878 : s->bits_sent += 2*16;
879 : s->bits_sent += stored_len<<3;
880 : #endif
881 0 : }
882 :
883 : /* ===========================================================================
884 : * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
885 : */
886 216 : void ZLIB_INTERNAL _tr_flush_bits(s)
887 : deflate_state *s;
888 : {
889 216 : bi_flush(s);
890 216 : }
891 :
892 : /* ===========================================================================
893 : * Send one empty static block to give enough lookahead for inflate.
894 : * This takes 10 bits, of which 7 may remain in the bit buffer.
895 : */
896 0 : void ZLIB_INTERNAL _tr_align(s)
897 : deflate_state *s;
898 : {
899 0 : send_bits(s, STATIC_TREES<<1, 3);
900 0 : send_code(s, END_BLOCK, static_ltree);
901 : #ifdef ZLIB_DEBUG
902 : s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
903 : #endif
904 0 : bi_flush(s);
905 0 : }
906 :
907 : /* ===========================================================================
908 : * Determine the best encoding for the current block: dynamic trees, static
909 : * trees or store, and write out the encoded block.
910 : */
911 72 : void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
912 : deflate_state *s;
913 : charf *buf; /* input block, or NULL if too old */
914 : ulg stored_len; /* length of input block */
915 : int last; /* one if this is the last block for a file */
916 : {
917 : ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
918 72 : int max_blindex = 0; /* index of last bit length code of non zero freq */
919 :
920 : /* Build the Huffman trees unless a stored block is forced */
921 72 : if (s->level > 0) {
922 :
923 : /* Check if the file is binary or text */
924 72 : if (s->strm->data_type == Z_UNKNOWN)
925 72 : s->strm->data_type = detect_data_type(s);
926 :
927 : /* Construct the literal and distance trees */
928 72 : build_tree(s, (tree_desc *)(&(s->l_desc)));
929 : Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
930 : s->static_len));
931 :
932 72 : build_tree(s, (tree_desc *)(&(s->d_desc)));
933 : Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
934 : s->static_len));
935 : /* At this point, opt_len and static_len are the total bit lengths of
936 : * the compressed block data, excluding the tree representations.
937 : */
938 :
939 : /* Build the bit length tree for the above two trees, and get the index
940 : * in bl_order of the last bit length code to send.
941 : */
942 72 : max_blindex = build_bl_tree(s);
943 :
944 : /* Determine the best encoding. Compute the block lengths in bytes. */
945 72 : opt_lenb = (s->opt_len+3+7)>>3;
946 72 : static_lenb = (s->static_len+3+7)>>3;
947 :
948 : Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
949 : opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
950 : s->last_lit));
951 :
952 72 : if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
953 :
954 : } else {
955 : Assert(buf != (char*)0, "lost buf");
956 0 : opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
957 : }
958 :
959 : #ifdef FORCE_STORED
960 : if (buf != (char*)0) { /* force stored block */
961 : #else
962 72 : if (stored_len+4 <= opt_lenb && buf != (char*)0) {
963 : /* 4: two words for the lengths */
964 : #endif
965 : /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
966 : * Otherwise we can't have processed more than WSIZE input bytes since
967 : * the last block flush, because compression would have been
968 : * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
969 : * transform a block into a stored block.
970 : */
971 0 : _tr_stored_block(s, buf, stored_len, last);
972 :
973 : #ifdef FORCE_STATIC
974 : } else if (static_lenb >= 0) { /* force static trees */
975 : #else
976 72 : } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
977 : #endif
978 72 : send_bits(s, (STATIC_TREES<<1)+last, 3);
979 72 : compress_block(s, (const ct_data *)static_ltree,
980 : (const ct_data *)static_dtree);
981 : #ifdef ZLIB_DEBUG
982 : s->compressed_len += 3 + s->static_len;
983 : #endif
984 : } else {
985 0 : send_bits(s, (DYN_TREES<<1)+last, 3);
986 0 : send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
987 : max_blindex+1);
988 0 : compress_block(s, (const ct_data *)s->dyn_ltree,
989 0 : (const ct_data *)s->dyn_dtree);
990 : #ifdef ZLIB_DEBUG
991 : s->compressed_len += 3 + s->opt_len;
992 : #endif
993 : }
994 : Assert (s->compressed_len == s->bits_sent, "bad compressed size");
995 : /* The above check is made mod 2^32, for files larger than 512 MB
996 : * and uLong implemented on 32 bits.
997 : */
998 72 : init_block(s);
999 :
1000 72 : if (last) {
1001 72 : bi_windup(s);
1002 : #ifdef ZLIB_DEBUG
1003 : s->compressed_len += 7; /* align on byte boundary */
1004 : #endif
1005 : }
1006 : Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1007 : s->compressed_len-7*last));
1008 72 : }
1009 :
1010 : /* ===========================================================================
1011 : * Save the match info and tally the frequency counts. Return true if
1012 : * the current block must be flushed.
1013 : */
1014 0 : int ZLIB_INTERNAL _tr_tally (s, dist, lc)
1015 : deflate_state *s;
1016 : unsigned dist; /* distance of matched string */
1017 : unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1018 : {
1019 0 : s->d_buf[s->last_lit] = (ush)dist;
1020 0 : s->l_buf[s->last_lit++] = (uch)lc;
1021 0 : if (dist == 0) {
1022 : /* lc is the unmatched char */
1023 0 : s->dyn_ltree[lc].Freq++;
1024 : } else {
1025 0 : s->matches++;
1026 : /* Here, lc is the match length - MIN_MATCH */
1027 0 : dist--; /* dist = match distance - 1 */
1028 : Assert((ush)dist < (ush)MAX_DIST(s) &&
1029 : (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1030 : (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1031 :
1032 0 : s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1033 0 : s->dyn_dtree[d_code(dist)].Freq++;
1034 : }
1035 :
1036 : #ifdef TRUNCATE_BLOCK
1037 : /* Try to guess if it is profitable to stop the current block here */
1038 : if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1039 : /* Compute an upper bound for the compressed length */
1040 : ulg out_length = (ulg)s->last_lit*8L;
1041 : ulg in_length = (ulg)((long)s->strstart - s->block_start);
1042 : int dcode;
1043 : for (dcode = 0; dcode < D_CODES; dcode++) {
1044 : out_length += (ulg)s->dyn_dtree[dcode].Freq *
1045 : (5L+extra_dbits[dcode]);
1046 : }
1047 : out_length >>= 3;
1048 : Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1049 : s->last_lit, in_length, out_length,
1050 : 100L - out_length*100L/in_length));
1051 : if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1052 : }
1053 : #endif
1054 0 : return (s->last_lit == s->lit_bufsize-1);
1055 : /* We avoid equality with lit_bufsize because of wraparound at 64K
1056 : * on 16 bit machines and because stored blocks are restricted to
1057 : * 64K-1 bytes.
1058 : */
1059 : }
1060 :
1061 : /* ===========================================================================
1062 : * Send the block data compressed using the given Huffman trees
1063 : */
1064 72 : local void compress_block(s, ltree, dtree)
1065 : deflate_state *s;
1066 : const ct_data *ltree; /* literal tree */
1067 : const ct_data *dtree; /* distance tree */
1068 : {
1069 : unsigned dist; /* distance of matched string */
1070 : int lc; /* match length or unmatched char (if dist == 0) */
1071 72 : unsigned lx = 0; /* running index in l_buf */
1072 : unsigned code; /* the code to send */
1073 : int extra; /* number of extra bits to send */
1074 :
1075 72 : if (s->last_lit != 0) do {
1076 0 : dist = s->d_buf[lx];
1077 0 : lc = s->l_buf[lx++];
1078 0 : if (dist == 0) {
1079 0 : send_code(s, lc, ltree); /* send a literal byte */
1080 : Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1081 : } else {
1082 : /* Here, lc is the match length - MIN_MATCH */
1083 0 : code = _length_code[lc];
1084 0 : send_code(s, code+LITERALS+1, ltree); /* send the length code */
1085 0 : extra = extra_lbits[code];
1086 0 : if (extra != 0) {
1087 0 : lc -= base_length[code];
1088 0 : send_bits(s, lc, extra); /* send the extra length bits */
1089 : }
1090 0 : dist--; /* dist is now the match distance - 1 */
1091 0 : code = d_code(dist);
1092 : Assert (code < D_CODES, "bad d_code");
1093 :
1094 0 : send_code(s, code, dtree); /* send the distance code */
1095 0 : extra = extra_dbits[code];
1096 0 : if (extra != 0) {
1097 0 : dist -= (unsigned)base_dist[code];
1098 0 : send_bits(s, dist, extra); /* send the extra distance bits */
1099 : }
1100 : } /* literal or match pair ? */
1101 :
1102 : /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1103 : Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1104 : "pendingBuf overflow");
1105 :
1106 0 : } while (lx < s->last_lit);
1107 :
1108 72 : send_code(s, END_BLOCK, ltree);
1109 72 : }
1110 :
1111 : /* ===========================================================================
1112 : * Check if the data type is TEXT or BINARY, using the following algorithm:
1113 : * - TEXT if the two conditions below are satisfied:
1114 : * a) There are no non-portable control characters belonging to the
1115 : * "black list" (0..6, 14..25, 28..31).
1116 : * b) There is at least one printable character belonging to the
1117 : * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1118 : * - BINARY otherwise.
1119 : * - The following partially-portable control characters form a
1120 : * "gray list" that is ignored in this detection algorithm:
1121 : * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1122 : * IN assertion: the fields Freq of dyn_ltree are set.
1123 : */
1124 72 : local int detect_data_type(s)
1125 : deflate_state *s;
1126 : {
1127 : /* black_mask is the bit mask of black-listed bytes
1128 : * set bits 0..6, 14..25, and 28..31
1129 : * 0xf3ffc07f = binary 11110011111111111100000001111111
1130 : */
1131 72 : unsigned long black_mask = 0xf3ffc07fUL;
1132 : int n;
1133 :
1134 : /* Check for non-textual ("black-listed") bytes. */
1135 2376 : for (n = 0; n <= 31; n++, black_mask >>= 1)
1136 2304 : if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1137 0 : return Z_BINARY;
1138 :
1139 : /* Check for textual ("white-listed") bytes. */
1140 72 : if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1141 72 : || s->dyn_ltree[13].Freq != 0)
1142 0 : return Z_TEXT;
1143 16200 : for (n = 32; n < LITERALS; n++)
1144 16128 : if (s->dyn_ltree[n].Freq != 0)
1145 0 : return Z_TEXT;
1146 :
1147 : /* There are no "black-listed" or "white-listed" bytes:
1148 : * this stream either is empty or has tolerated ("gray-listed") bytes only.
1149 : */
1150 72 : return Z_BINARY;
1151 : }
1152 :
1153 : /* ===========================================================================
1154 : * Reverse the first len bits of a code, using straightforward code (a faster
1155 : * method would use a table)
1156 : * IN assertion: 1 <= len <= 15
1157 : */
1158 432 : local unsigned bi_reverse(code, len)
1159 : unsigned code; /* the value to invert */
1160 : int len; /* its bit length */
1161 : {
1162 432 : register unsigned res = 0;
1163 : do {
1164 432 : res |= code & 1;
1165 432 : code >>= 1, res <<= 1;
1166 432 : } while (--len > 0);
1167 432 : return res >> 1;
1168 : }
1169 :
1170 : /* ===========================================================================
1171 : * Flush the bit buffer, keeping at most 7 bits in it.
1172 : */
1173 216 : local void bi_flush(s)
1174 : deflate_state *s;
1175 : {
1176 216 : if (s->bi_valid == 16) {
1177 0 : put_short(s, s->bi_buf);
1178 0 : s->bi_buf = 0;
1179 0 : s->bi_valid = 0;
1180 216 : } else if (s->bi_valid >= 8) {
1181 0 : put_byte(s, (Byte)s->bi_buf);
1182 0 : s->bi_buf >>= 8;
1183 0 : s->bi_valid -= 8;
1184 : }
1185 216 : }
1186 :
1187 : /* ===========================================================================
1188 : * Flush the bit buffer and align the output on a byte boundary
1189 : */
1190 72 : local void bi_windup(s)
1191 : deflate_state *s;
1192 : {
1193 72 : if (s->bi_valid > 8) {
1194 72 : put_short(s, s->bi_buf);
1195 0 : } else if (s->bi_valid > 0) {
1196 0 : put_byte(s, (Byte)s->bi_buf);
1197 : }
1198 72 : s->bi_buf = 0;
1199 72 : s->bi_valid = 0;
1200 : #ifdef ZLIB_DEBUG
1201 : s->bits_sent = (s->bits_sent+7) & ~7;
1202 : #endif
1203 72 : }
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