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1 | /* +++ trees.c */ |
2 | /* trees.c -- output deflated data using Huffman coding |
3 | * Copyright (C) 1995-1996 Jean-loup Gailly |
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 | /* From: trees.c,v 1.11 1996/07/24 13:41:06 me Exp $ */ |
34 | |
35 | /* #include "deflate.h" */ |
36 | |
37 | #include <linux/zutil.h> |
38 | #include "defutil.h" |
39 | |
40 | #ifdef DEBUG_ZLIB |
41 | # include <ctype.h> |
42 | #endif |
43 | |
44 | /* =========================================================================== |
45 | * Constants |
46 | */ |
47 | |
48 | #define MAX_BL_BITS 7 |
49 | /* Bit length codes must not exceed MAX_BL_BITS bits */ |
50 | |
51 | #define END_BLOCK 256 |
52 | /* end of block literal code */ |
53 | |
54 | #define REP_3_6 16 |
55 | /* repeat previous bit length 3-6 times (2 bits of repeat count) */ |
56 | |
57 | #define REPZ_3_10 17 |
58 | /* repeat a zero length 3-10 times (3 bits of repeat count) */ |
59 | |
60 | #define REPZ_11_138 18 |
61 | /* repeat a zero length 11-138 times (7 bits of repeat count) */ |
62 | |
63 | static const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ |
64 | = {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}; |
65 | |
66 | static const int extra_dbits[D_CODES] /* extra bits for each distance code */ |
67 | = {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}; |
68 | |
69 | static const int extra_blbits[BL_CODES]/* extra bits for each bit length code */ |
70 | = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; |
71 | |
72 | static const uch bl_order[BL_CODES] |
73 | = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; |
74 | /* The lengths of the bit length codes are sent in order of decreasing |
75 | * probability, to avoid transmitting the lengths for unused bit length codes. |
76 | */ |
77 | |
78 | #define Buf_size (8 * 2*sizeof(char)) |
79 | /* Number of bits used within bi_buf. (bi_buf might be implemented on |
80 | * more than 16 bits on some systems.) |
81 | */ |
82 | |
83 | /* =========================================================================== |
84 | * Local data. These are initialized only once. |
85 | */ |
86 | |
87 | static ct_data static_ltree[L_CODES+2]; |
88 | /* The static literal tree. Since the bit lengths are imposed, there is no |
89 | * need for the L_CODES extra codes used during heap construction. However |
90 | * The codes 286 and 287 are needed to build a canonical tree (see zlib_tr_init |
91 | * below). |
92 | */ |
93 | |
94 | static ct_data static_dtree[D_CODES]; |
95 | /* The static distance tree. (Actually a trivial tree since all codes use |
96 | * 5 bits.) |
97 | */ |
98 | |
99 | static uch dist_code[512]; |
100 | /* distance codes. The first 256 values correspond to the distances |
101 | * 3 .. 258, the last 256 values correspond to the top 8 bits of |
102 | * the 15 bit distances. |
103 | */ |
104 | |
105 | static uch length_code[MAX_MATCH-MIN_MATCH+1]; |
106 | /* length code for each normalized match length (0 == MIN_MATCH) */ |
107 | |
108 | static int base_length[LENGTH_CODES]; |
109 | /* First normalized length for each code (0 = MIN_MATCH) */ |
110 | |
111 | static int base_dist[D_CODES]; |
112 | /* First normalized distance for each code (0 = distance of 1) */ |
113 | |
114 | struct static_tree_desc_s { |
115 | const ct_data *static_tree; /* static tree or NULL */ |
116 | const int *extra_bits; /* extra bits for each code or NULL */ |
117 | int extra_base; /* base index for extra_bits */ |
118 | int elems; /* max number of elements in the tree */ |
119 | int max_length; /* max bit length for the codes */ |
120 | }; |
121 | |
122 | static static_tree_desc static_l_desc = |
123 | {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; |
124 | |
125 | static static_tree_desc static_d_desc = |
126 | {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; |
127 | |
128 | static static_tree_desc static_bl_desc = |
129 | {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; |
130 | |
131 | /* =========================================================================== |
132 | * Local (static) routines in this file. |
133 | */ |
134 | |
135 | static void tr_static_init (void); |
136 | static void init_block (deflate_state *s); |
137 | static void pqdownheap (deflate_state *s, ct_data *tree, int k); |
138 | static void gen_bitlen (deflate_state *s, tree_desc *desc); |
139 | static void gen_codes (ct_data *tree, int max_code, ush *bl_count); |
140 | static void build_tree (deflate_state *s, tree_desc *desc); |
141 | static void scan_tree (deflate_state *s, ct_data *tree, int max_code); |
142 | static void send_tree (deflate_state *s, ct_data *tree, int max_code); |
143 | static int build_bl_tree (deflate_state *s); |
144 | static void send_all_trees (deflate_state *s, int lcodes, int dcodes, |
145 | int blcodes); |
146 | static void compress_block (deflate_state *s, ct_data *ltree, |
147 | ct_data *dtree); |
148 | static void set_data_type (deflate_state *s); |
149 | static unsigned bi_reverse (unsigned value, int length); |
150 | static void bi_windup (deflate_state *s); |
151 | static void bi_flush (deflate_state *s); |
152 | static void copy_block (deflate_state *s, char *buf, unsigned len, |
153 | int header); |
154 | |
155 | #ifndef DEBUG_ZLIB |
156 | # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len) |
157 | /* Send a code of the given tree. c and tree must not have side effects */ |
158 | |
159 | #else /* DEBUG_ZLIB */ |
160 | # define send_code(s, c, tree) \ |
161 | { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \ |
162 | send_bits(s, tree[c].Code, tree[c].Len); } |
163 | #endif |
164 | |
165 | #define d_code(dist) \ |
166 | ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)]) |
167 | /* Mapping from a distance to a distance code. dist is the distance - 1 and |
168 | * must not have side effects. dist_code[256] and dist_code[257] are never |
169 | * used. |
170 | */ |
171 | |
172 | /* =========================================================================== |
173 | * Send a value on a given number of bits. |
174 | * IN assertion: length <= 16 and value fits in length bits. |
175 | */ |
176 | #ifdef DEBUG_ZLIB |
177 | static void send_bits (deflate_state *s, int value, int length); |
178 | |
179 | static void send_bits( |
180 | deflate_state *s, |
181 | int value, /* value to send */ |
182 | int length /* number of bits */ |
183 | ) |
184 | { |
185 | Tracevv((stderr," l %2d v %4x ", length, value)); |
186 | Assert(length > 0 && length <= 15, "invalid length"); |
187 | s->bits_sent += (ulg)length; |
188 | |
189 | /* If not enough room in bi_buf, use (valid) bits from bi_buf and |
190 | * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid)) |
191 | * unused bits in value. |
192 | */ |
193 | if (s->bi_valid > (int)Buf_size - length) { |
194 | s->bi_buf |= (value << s->bi_valid); |
195 | put_short(s, s->bi_buf); |
196 | s->bi_buf = (ush)value >> (Buf_size - s->bi_valid); |
197 | s->bi_valid += length - Buf_size; |
198 | } else { |
199 | s->bi_buf |= value << s->bi_valid; |
200 | s->bi_valid += length; |
201 | } |
202 | } |
203 | #else /* !DEBUG_ZLIB */ |
204 | |
205 | #define send_bits(s, value, length) \ |
206 | { int len = length;\ |
207 | if (s->bi_valid > (int)Buf_size - len) {\ |
208 | int val = value;\ |
209 | s->bi_buf |= (val << s->bi_valid);\ |
210 | put_short(s, s->bi_buf);\ |
211 | s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\ |
212 | s->bi_valid += len - Buf_size;\ |
213 | } else {\ |
214 | s->bi_buf |= (value) << s->bi_valid;\ |
215 | s->bi_valid += len;\ |
216 | }\ |
217 | } |
218 | #endif /* DEBUG_ZLIB */ |
219 | |
220 | /* =========================================================================== |
221 | * Initialize the various 'constant' tables. In a multi-threaded environment, |
222 | * this function may be called by two threads concurrently, but this is |
223 | * harmless since both invocations do exactly the same thing. |
224 | */ |
225 | static void tr_static_init(void) |
226 | { |
227 | static int static_init_done; |
228 | int n; /* iterates over tree elements */ |
229 | int bits; /* bit counter */ |
230 | int length; /* length value */ |
231 | int code; /* code value */ |
232 | int dist; /* distance index */ |
233 | ush bl_count[MAX_BITS+1]; |
234 | /* number of codes at each bit length for an optimal tree */ |
235 | |
236 | if (static_init_done) return; |
237 | |
238 | /* Initialize the mapping length (0..255) -> length code (0..28) */ |
239 | length = 0; |
240 | for (code = 0; code < LENGTH_CODES-1; code++) { |
241 | base_length[code] = length; |
242 | for (n = 0; n < (1<<extra_lbits[code]); n++) { |
243 | length_code[length++] = (uch)code; |
244 | } |
245 | } |
246 | Assert (length == 256, "tr_static_init: length != 256"); |
247 | /* Note that the length 255 (match length 258) can be represented |
248 | * in two different ways: code 284 + 5 bits or code 285, so we |
249 | * overwrite length_code[255] to use the best encoding: |
250 | */ |
251 | length_code[length-1] = (uch)code; |
252 | |
253 | /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ |
254 | dist = 0; |
255 | for (code = 0 ; code < 16; code++) { |
256 | base_dist[code] = dist; |
257 | for (n = 0; n < (1<<extra_dbits[code]); n++) { |
258 | dist_code[dist++] = (uch)code; |
259 | } |
260 | } |
261 | Assert (dist == 256, "tr_static_init: dist != 256"); |
262 | dist >>= 7; /* from now on, all distances are divided by 128 */ |
263 | for ( ; code < D_CODES; code++) { |
264 | base_dist[code] = dist << 7; |
265 | for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { |
266 | dist_code[256 + dist++] = (uch)code; |
267 | } |
268 | } |
269 | Assert (dist == 256, "tr_static_init: 256+dist != 512"); |
270 | |
271 | /* Construct the codes of the static literal tree */ |
272 | for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; |
273 | n = 0; |
274 | while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; |
275 | while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; |
276 | while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; |
277 | while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; |
278 | /* Codes 286 and 287 do not exist, but we must include them in the |
279 | * tree construction to get a canonical Huffman tree (longest code |
280 | * all ones) |
281 | */ |
282 | gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count); |
283 | |
284 | /* The static distance tree is trivial: */ |
285 | for (n = 0; n < D_CODES; n++) { |
286 | static_dtree[n].Len = 5; |
287 | static_dtree[n].Code = bi_reverse((unsigned)n, 5); |
288 | } |
289 | static_init_done = 1; |
290 | } |
291 | |
292 | /* =========================================================================== |
293 | * Initialize the tree data structures for a new zlib stream. |
294 | */ |
295 | void zlib_tr_init( |
296 | deflate_state *s |
297 | ) |
298 | { |
299 | tr_static_init(); |
300 | |
301 | s->compressed_len = 0L; |
302 | |
303 | s->l_desc.dyn_tree = s->dyn_ltree; |
304 | s->l_desc.stat_desc = &static_l_desc; |
305 | |
306 | s->d_desc.dyn_tree = s->dyn_dtree; |
307 | s->d_desc.stat_desc = &static_d_desc; |
308 | |
309 | s->bl_desc.dyn_tree = s->bl_tree; |
310 | s->bl_desc.stat_desc = &static_bl_desc; |
311 | |
312 | s->bi_buf = 0; |
313 | s->bi_valid = 0; |
314 | s->last_eob_len = 8; /* enough lookahead for inflate */ |
315 | #ifdef DEBUG_ZLIB |
316 | s->bits_sent = 0L; |
317 | #endif |
318 | |
319 | /* Initialize the first block of the first file: */ |
320 | init_block(s); |
321 | } |
322 | |
323 | /* =========================================================================== |
324 | * Initialize a new block. |
325 | */ |
326 | static void init_block( |
327 | deflate_state *s |
328 | ) |
329 | { |
330 | int n; /* iterates over tree elements */ |
331 | |
332 | /* Initialize the trees. */ |
333 | for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0; |
334 | for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0; |
335 | for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0; |
336 | |
337 | s->dyn_ltree[END_BLOCK].Freq = 1; |
338 | s->opt_len = s->static_len = 0L; |
339 | s->last_lit = s->matches = 0; |
340 | } |
341 | |
342 | #define SMALLEST 1 |
343 | /* Index within the heap array of least frequent node in the Huffman tree */ |
344 | |
345 | |
346 | /* =========================================================================== |
347 | * Remove the smallest element from the heap and recreate the heap with |
348 | * one less element. Updates heap and heap_len. |
349 | */ |
350 | #define pqremove(s, tree, top) \ |
351 | {\ |
352 | top = s->heap[SMALLEST]; \ |
353 | s->heap[SMALLEST] = s->heap[s->heap_len--]; \ |
354 | pqdownheap(s, tree, SMALLEST); \ |
355 | } |
356 | |
357 | /* =========================================================================== |
358 | * Compares to subtrees, using the tree depth as tie breaker when |
359 | * the subtrees have equal frequency. This minimizes the worst case length. |
360 | */ |
361 | #define smaller(tree, n, m, depth) \ |
362 | (tree[n].Freq < tree[m].Freq || \ |
363 | (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) |
364 | |
365 | /* =========================================================================== |
366 | * Restore the heap property by moving down the tree starting at node k, |
367 | * exchanging a node with the smallest of its two sons if necessary, stopping |
368 | * when the heap property is re-established (each father smaller than its |
369 | * two sons). |
370 | */ |
371 | static void pqdownheap( |
372 | deflate_state *s, |
373 | ct_data *tree, /* the tree to restore */ |
374 | int k /* node to move down */ |
375 | ) |
376 | { |
377 | int v = s->heap[k]; |
378 | int j = k << 1; /* left son of k */ |
379 | while (j <= s->heap_len) { |
380 | /* Set j to the smallest of the two sons: */ |
381 | if (j < s->heap_len && |
382 | smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { |
383 | j++; |
384 | } |
385 | /* Exit if v is smaller than both sons */ |
386 | if (smaller(tree, v, s->heap[j], s->depth)) break; |
387 | |
388 | /* Exchange v with the smallest son */ |
389 | s->heap[k] = s->heap[j]; k = j; |
390 | |
391 | /* And continue down the tree, setting j to the left son of k */ |
392 | j <<= 1; |
393 | } |
394 | s->heap[k] = v; |
395 | } |
396 | |
397 | /* =========================================================================== |
398 | * Compute the optimal bit lengths for a tree and update the total bit length |
399 | * for the current block. |
400 | * IN assertion: the fields freq and dad are set, heap[heap_max] and |
401 | * above are the tree nodes sorted by increasing frequency. |
402 | * OUT assertions: the field len is set to the optimal bit length, the |
403 | * array bl_count contains the frequencies for each bit length. |
404 | * The length opt_len is updated; static_len is also updated if stree is |
405 | * not null. |
406 | */ |
407 | static void gen_bitlen( |
408 | deflate_state *s, |
409 | tree_desc *desc /* the tree descriptor */ |
410 | ) |
411 | { |
412 | ct_data *tree = desc->dyn_tree; |
413 | int max_code = desc->max_code; |
414 | const ct_data *stree = desc->stat_desc->static_tree; |
415 | const int *extra = desc->stat_desc->extra_bits; |
416 | int base = desc->stat_desc->extra_base; |
417 | int max_length = desc->stat_desc->max_length; |
418 | int h; /* heap index */ |
419 | int n, m; /* iterate over the tree elements */ |
420 | int bits; /* bit length */ |
421 | int xbits; /* extra bits */ |
422 | ush f; /* frequency */ |
423 | int overflow = 0; /* number of elements with bit length too large */ |
424 | |
425 | for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0; |
426 | |
427 | /* In a first pass, compute the optimal bit lengths (which may |
428 | * overflow in the case of the bit length tree). |
429 | */ |
430 | tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ |
431 | |
432 | for (h = s->heap_max+1; h < HEAP_SIZE; h++) { |
433 | n = s->heap[h]; |
434 | bits = tree[tree[n].Dad].Len + 1; |
435 | if (bits > max_length) bits = max_length, overflow++; |
436 | tree[n].Len = (ush)bits; |
437 | /* We overwrite tree[n].Dad which is no longer needed */ |
438 | |
439 | if (n > max_code) continue; /* not a leaf node */ |
440 | |
441 | s->bl_count[bits]++; |
442 | xbits = 0; |
443 | if (n >= base) xbits = extra[n-base]; |
444 | f = tree[n].Freq; |
445 | s->opt_len += (ulg)f * (bits + xbits); |
446 | if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits); |
447 | } |
448 | if (overflow == 0) return; |
449 | |
450 | Trace((stderr,"\nbit length overflow\n")); |
451 | /* This happens for example on obj2 and pic of the Calgary corpus */ |
452 | |
453 | /* Find the first bit length which could increase: */ |
454 | do { |
455 | bits = max_length-1; |
456 | while (s->bl_count[bits] == 0) bits--; |
457 | s->bl_count[bits]--; /* move one leaf down the tree */ |
458 | s->bl_count[bits+1] += 2; /* move one overflow item as its brother */ |
459 | s->bl_count[max_length]--; |
460 | /* The brother of the overflow item also moves one step up, |
461 | * but this does not affect bl_count[max_length] |
462 | */ |
463 | overflow -= 2; |
464 | } while (overflow > 0); |
465 | |
466 | /* Now recompute all bit lengths, scanning in increasing frequency. |
467 | * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all |
468 | * lengths instead of fixing only the wrong ones. This idea is taken |
469 | * from 'ar' written by Haruhiko Okumura.) |
470 | */ |
471 | for (bits = max_length; bits != 0; bits--) { |
472 | n = s->bl_count[bits]; |
473 | while (n != 0) { |
474 | m = s->heap[--h]; |
475 | if (m > max_code) continue; |
476 | if (tree[m].Len != (unsigned) bits) { |
477 | Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); |
478 | s->opt_len += ((long)bits - (long)tree[m].Len) |
479 | *(long)tree[m].Freq; |
480 | tree[m].Len = (ush)bits; |
481 | } |
482 | n--; |
483 | } |
484 | } |
485 | } |
486 | |
487 | /* =========================================================================== |
488 | * Generate the codes for a given tree and bit counts (which need not be |
489 | * optimal). |
490 | * IN assertion: the array bl_count contains the bit length statistics for |
491 | * the given tree and the field len is set for all tree elements. |
492 | * OUT assertion: the field code is set for all tree elements of non |
493 | * zero code length. |
494 | */ |
495 | static void gen_codes( |
496 | ct_data *tree, /* the tree to decorate */ |
497 | int max_code, /* largest code with non zero frequency */ |
498 | ush *bl_count /* number of codes at each bit length */ |
499 | ) |
500 | { |
501 | ush next_code[MAX_BITS+1]; /* next code value for each bit length */ |
502 | ush code = 0; /* running code value */ |
503 | int bits; /* bit index */ |
504 | int n; /* code index */ |
505 | |
506 | /* The distribution counts are first used to generate the code values |
507 | * without bit reversal. |
508 | */ |
509 | for (bits = 1; bits <= MAX_BITS; bits++) { |
510 | next_code[bits] = code = (code + bl_count[bits-1]) << 1; |
511 | } |
512 | /* Check that the bit counts in bl_count are consistent. The last code |
513 | * must be all ones. |
514 | */ |
515 | Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, |
516 | "inconsistent bit counts"); |
517 | Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); |
518 | |
519 | for (n = 0; n <= max_code; n++) { |
520 | int len = tree[n].Len; |
521 | if (len == 0) continue; |
522 | /* Now reverse the bits */ |
523 | tree[n].Code = bi_reverse(next_code[len]++, len); |
524 | |
525 | Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", |
526 | n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); |
527 | } |
528 | } |
529 | |
530 | /* =========================================================================== |
531 | * Construct one Huffman tree and assigns the code bit strings and lengths. |
532 | * Update the total bit length for the current block. |
533 | * IN assertion: the field freq is set for all tree elements. |
534 | * OUT assertions: the fields len and code are set to the optimal bit length |
535 | * and corresponding code. The length opt_len is updated; static_len is |
536 | * also updated if stree is not null. The field max_code is set. |
537 | */ |
538 | static void build_tree( |
539 | deflate_state *s, |
540 | tree_desc *desc /* the tree descriptor */ |
541 | ) |
542 | { |
543 | ct_data *tree = desc->dyn_tree; |
544 | const ct_data *stree = desc->stat_desc->static_tree; |
545 | int elems = desc->stat_desc->elems; |
546 | int n, m; /* iterate over heap elements */ |
547 | int max_code = -1; /* largest code with non zero frequency */ |
548 | int node; /* new node being created */ |
549 | |
550 | /* Construct the initial heap, with least frequent element in |
551 | * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. |
552 | * heap[0] is not used. |
553 | */ |
554 | s->heap_len = 0, s->heap_max = HEAP_SIZE; |
555 | |
556 | for (n = 0; n < elems; n++) { |
557 | if (tree[n].Freq != 0) { |
558 | s->heap[++(s->heap_len)] = max_code = n; |
559 | s->depth[n] = 0; |
560 | } else { |
561 | tree[n].Len = 0; |
562 | } |
563 | } |
564 | |
565 | /* The pkzip format requires that at least one distance code exists, |
566 | * and that at least one bit should be sent even if there is only one |
567 | * possible code. So to avoid special checks later on we force at least |
568 | * two codes of non zero frequency. |
569 | */ |
570 | while (s->heap_len < 2) { |
571 | node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0); |
572 | tree[node].Freq = 1; |
573 | s->depth[node] = 0; |
574 | s->opt_len--; if (stree) s->static_len -= stree[node].Len; |
575 | /* node is 0 or 1 so it does not have extra bits */ |
576 | } |
577 | desc->max_code = max_code; |
578 | |
579 | /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, |
580 | * establish sub-heaps of increasing lengths: |
581 | */ |
582 | for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n); |
583 | |
584 | /* Construct the Huffman tree by repeatedly combining the least two |
585 | * frequent nodes. |
586 | */ |
587 | node = elems; /* next internal node of the tree */ |
588 | do { |
589 | pqremove(s, tree, n); /* n = node of least frequency */ |
590 | m = s->heap[SMALLEST]; /* m = node of next least frequency */ |
591 | |
592 | s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */ |
593 | s->heap[--(s->heap_max)] = m; |
594 | |
595 | /* Create a new node father of n and m */ |
596 | tree[node].Freq = tree[n].Freq + tree[m].Freq; |
597 | s->depth[node] = (uch) (max(s->depth[n], s->depth[m]) + 1); |
598 | tree[n].Dad = tree[m].Dad = (ush)node; |
599 | #ifdef DUMP_BL_TREE |
600 | if (tree == s->bl_tree) { |
601 | fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", |
602 | node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); |
603 | } |
604 | #endif |
605 | /* and insert the new node in the heap */ |
606 | s->heap[SMALLEST] = node++; |
607 | pqdownheap(s, tree, SMALLEST); |
608 | |
609 | } while (s->heap_len >= 2); |
610 | |
611 | s->heap[--(s->heap_max)] = s->heap[SMALLEST]; |
612 | |
613 | /* At this point, the fields freq and dad are set. We can now |
614 | * generate the bit lengths. |
615 | */ |
616 | gen_bitlen(s, (tree_desc *)desc); |
617 | |
618 | /* The field len is now set, we can generate the bit codes */ |
619 | gen_codes ((ct_data *)tree, max_code, s->bl_count); |
620 | } |
621 | |
622 | /* =========================================================================== |
623 | * Scan a literal or distance tree to determine the frequencies of the codes |
624 | * in the bit length tree. |
625 | */ |
626 | static void scan_tree( |
627 | deflate_state *s, |
628 | ct_data *tree, /* the tree to be scanned */ |
629 | int max_code /* and its largest code of non zero frequency */ |
630 | ) |
631 | { |
632 | int n; /* iterates over all tree elements */ |
633 | int prevlen = -1; /* last emitted length */ |
634 | int curlen; /* length of current code */ |
635 | int nextlen = tree[0].Len; /* length of next code */ |
636 | int count = 0; /* repeat count of the current code */ |
637 | int max_count = 7; /* max repeat count */ |
638 | int min_count = 4; /* min repeat count */ |
639 | |
640 | if (nextlen == 0) max_count = 138, min_count = 3; |
641 | tree[max_code+1].Len = (ush)0xffff; /* guard */ |
642 | |
643 | for (n = 0; n <= max_code; n++) { |
644 | curlen = nextlen; nextlen = tree[n+1].Len; |
645 | if (++count < max_count && curlen == nextlen) { |
646 | continue; |
647 | } else if (count < min_count) { |
648 | s->bl_tree[curlen].Freq += count; |
649 | } else if (curlen != 0) { |
650 | if (curlen != prevlen) s->bl_tree[curlen].Freq++; |
651 | s->bl_tree[REP_3_6].Freq++; |
652 | } else if (count <= 10) { |
653 | s->bl_tree[REPZ_3_10].Freq++; |
654 | } else { |
655 | s->bl_tree[REPZ_11_138].Freq++; |
656 | } |
657 | count = 0; prevlen = curlen; |
658 | if (nextlen == 0) { |
659 | max_count = 138, min_count = 3; |
660 | } else if (curlen == nextlen) { |
661 | max_count = 6, min_count = 3; |
662 | } else { |
663 | max_count = 7, min_count = 4; |
664 | } |
665 | } |
666 | } |
667 | |
668 | /* =========================================================================== |
669 | * Send a literal or distance tree in compressed form, using the codes in |
670 | * bl_tree. |
671 | */ |
672 | static void send_tree( |
673 | deflate_state *s, |
674 | ct_data *tree, /* the tree to be scanned */ |
675 | int max_code /* and its largest code of non zero frequency */ |
676 | ) |
677 | { |
678 | int n; /* iterates over all tree elements */ |
679 | int prevlen = -1; /* last emitted length */ |
680 | int curlen; /* length of current code */ |
681 | int nextlen = tree[0].Len; /* length of next code */ |
682 | int count = 0; /* repeat count of the current code */ |
683 | int max_count = 7; /* max repeat count */ |
684 | int min_count = 4; /* min repeat count */ |
685 | |
686 | /* tree[max_code+1].Len = -1; */ /* guard already set */ |
687 | if (nextlen == 0) max_count = 138, min_count = 3; |
688 | |
689 | for (n = 0; n <= max_code; n++) { |
690 | curlen = nextlen; nextlen = tree[n+1].Len; |
691 | if (++count < max_count && curlen == nextlen) { |
692 | continue; |
693 | } else if (count < min_count) { |
694 | do { send_code(s, curlen, s->bl_tree); } while (--count != 0); |
695 | |
696 | } else if (curlen != 0) { |
697 | if (curlen != prevlen) { |
698 | send_code(s, curlen, s->bl_tree); count--; |
699 | } |
700 | Assert(count >= 3 && count <= 6, " 3_6?"); |
701 | send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2); |
702 | |
703 | } else if (count <= 10) { |
704 | send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3); |
705 | |
706 | } else { |
707 | send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7); |
708 | } |
709 | count = 0; prevlen = curlen; |
710 | if (nextlen == 0) { |
711 | max_count = 138, min_count = 3; |
712 | } else if (curlen == nextlen) { |
713 | max_count = 6, min_count = 3; |
714 | } else { |
715 | max_count = 7, min_count = 4; |
716 | } |
717 | } |
718 | } |
719 | |
720 | /* =========================================================================== |
721 | * Construct the Huffman tree for the bit lengths and return the index in |
722 | * bl_order of the last bit length code to send. |
723 | */ |
724 | static int build_bl_tree( |
725 | deflate_state *s |
726 | ) |
727 | { |
728 | int max_blindex; /* index of last bit length code of non zero freq */ |
729 | |
730 | /* Determine the bit length frequencies for literal and distance trees */ |
731 | scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code); |
732 | scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code); |
733 | |
734 | /* Build the bit length tree: */ |
735 | build_tree(s, (tree_desc *)(&(s->bl_desc))); |
736 | /* opt_len now includes the length of the tree representations, except |
737 | * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. |
738 | */ |
739 | |
740 | /* Determine the number of bit length codes to send. The pkzip format |
741 | * requires that at least 4 bit length codes be sent. (appnote.txt says |
742 | * 3 but the actual value used is 4.) |
743 | */ |
744 | for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { |
745 | if (s->bl_tree[bl_order[max_blindex]].Len != 0) break; |
746 | } |
747 | /* Update opt_len to include the bit length tree and counts */ |
748 | s->opt_len += 3*(max_blindex+1) + 5+5+4; |
749 | Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", |
750 | s->opt_len, s->static_len)); |
751 | |
752 | return max_blindex; |
753 | } |
754 | |
755 | /* =========================================================================== |
756 | * Send the header for a block using dynamic Huffman trees: the counts, the |
757 | * lengths of the bit length codes, the literal tree and the distance tree. |
758 | * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. |
759 | */ |
760 | static void send_all_trees( |
761 | deflate_state *s, |
762 | int lcodes, /* number of codes for each tree */ |
763 | int dcodes, /* number of codes for each tree */ |
764 | int blcodes /* number of codes for each tree */ |
765 | ) |
766 | { |
767 | int rank; /* index in bl_order */ |
768 | |
769 | Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); |
770 | Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, |
771 | "too many codes"); |
772 | Tracev((stderr, "\nbl counts: ")); |
773 | send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */ |
774 | send_bits(s, dcodes-1, 5); |
775 | send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */ |
776 | for (rank = 0; rank < blcodes; rank++) { |
777 | Tracev((stderr, "\nbl code %2d ", bl_order[rank])); |
778 | send_bits(s, s->bl_tree[bl_order[rank]].Len, 3); |
779 | } |
780 | Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent)); |
781 | |
782 | send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */ |
783 | Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent)); |
784 | |
785 | send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */ |
786 | Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent)); |
787 | } |
788 | |
789 | /* =========================================================================== |
790 | * Send a stored block |
791 | */ |
792 | void zlib_tr_stored_block( |
793 | deflate_state *s, |
794 | char *buf, /* input block */ |
795 | ulg stored_len, /* length of input block */ |
796 | int eof /* true if this is the last block for a file */ |
797 | ) |
798 | { |
799 | send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */ |
800 | s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L; |
801 | s->compressed_len += (stored_len + 4) << 3; |
802 | |
803 | copy_block(s, buf, (unsigned)stored_len, 1); /* with header */ |
804 | } |
805 | |
806 | /* Send just the `stored block' type code without any length bytes or data. |
807 | */ |
808 | void zlib_tr_stored_type_only( |
809 | deflate_state *s |
810 | ) |
811 | { |
812 | send_bits(s, (STORED_BLOCK << 1), 3); |
813 | bi_windup(s); |
814 | s->compressed_len = (s->compressed_len + 3) & ~7L; |
815 | } |
816 | |
817 | |
818 | /* =========================================================================== |
819 | * Send one empty static block to give enough lookahead for inflate. |
820 | * This takes 10 bits, of which 7 may remain in the bit buffer. |
821 | * The current inflate code requires 9 bits of lookahead. If the |
822 | * last two codes for the previous block (real code plus EOB) were coded |
823 | * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode |
824 | * the last real code. In this case we send two empty static blocks instead |
825 | * of one. (There are no problems if the previous block is stored or fixed.) |
826 | * To simplify the code, we assume the worst case of last real code encoded |
827 | * on one bit only. |
828 | */ |
829 | void zlib_tr_align( |
830 | deflate_state *s |
831 | ) |
832 | { |
833 | send_bits(s, STATIC_TREES<<1, 3); |
834 | send_code(s, END_BLOCK, static_ltree); |
835 | s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ |
836 | bi_flush(s); |
837 | /* Of the 10 bits for the empty block, we have already sent |
838 | * (10 - bi_valid) bits. The lookahead for the last real code (before |
839 | * the EOB of the previous block) was thus at least one plus the length |
840 | * of the EOB plus what we have just sent of the empty static block. |
841 | */ |
842 | if (1 + s->last_eob_len + 10 - s->bi_valid < 9) { |
843 | send_bits(s, STATIC_TREES<<1, 3); |
844 | send_code(s, END_BLOCK, static_ltree); |
845 | s->compressed_len += 10L; |
846 | bi_flush(s); |
847 | } |
848 | s->last_eob_len = 7; |
849 | } |
850 | |
851 | /* =========================================================================== |
852 | * Determine the best encoding for the current block: dynamic trees, static |
853 | * trees or store, and output the encoded block to the zip file. This function |
854 | * returns the total compressed length for the file so far. |
855 | */ |
856 | ulg zlib_tr_flush_block( |
857 | deflate_state *s, |
858 | char *buf, /* input block, or NULL if too old */ |
859 | ulg stored_len, /* length of input block */ |
860 | int eof /* true if this is the last block for a file */ |
861 | ) |
862 | { |
863 | ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ |
864 | int max_blindex = 0; /* index of last bit length code of non zero freq */ |
865 | |
866 | /* Build the Huffman trees unless a stored block is forced */ |
867 | if (s->level > 0) { |
868 | |
869 | /* Check if the file is ascii or binary */ |
870 | if (s->data_type == Z_UNKNOWN) set_data_type(s); |
871 | |
872 | /* Construct the literal and distance trees */ |
873 | build_tree(s, (tree_desc *)(&(s->l_desc))); |
874 | Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len, |
875 | s->static_len)); |
876 | |
877 | build_tree(s, (tree_desc *)(&(s->d_desc))); |
878 | Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len, |
879 | s->static_len)); |
880 | /* At this point, opt_len and static_len are the total bit lengths of |
881 | * the compressed block data, excluding the tree representations. |
882 | */ |
883 | |
884 | /* Build the bit length tree for the above two trees, and get the index |
885 | * in bl_order of the last bit length code to send. |
886 | */ |
887 | max_blindex = build_bl_tree(s); |
888 | |
889 | /* Determine the best encoding. Compute first the block length in bytes*/ |
890 | opt_lenb = (s->opt_len+3+7)>>3; |
891 | static_lenb = (s->static_len+3+7)>>3; |
892 | |
893 | Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ", |
894 | opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, |
895 | s->last_lit)); |
896 | |
897 | if (static_lenb <= opt_lenb) opt_lenb = static_lenb; |
898 | |
899 | } else { |
900 | Assert(buf != (char*)0, "lost buf"); |
901 | opt_lenb = static_lenb = stored_len + 5; /* force a stored block */ |
902 | } |
903 | |
904 | /* If compression failed and this is the first and last block, |
905 | * and if the .zip file can be seeked (to rewrite the local header), |
906 | * the whole file is transformed into a stored file: |
907 | */ |
908 | #ifdef STORED_FILE_OK |
909 | # ifdef FORCE_STORED_FILE |
910 | if (eof && s->compressed_len == 0L) { /* force stored file */ |
911 | # else |
912 | if (stored_len <= opt_lenb && eof && s->compressed_len==0L && seekable()) { |
913 | # endif |
914 | /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ |
915 | if (buf == (char*)0) error ("block vanished"); |
916 | |
917 | copy_block(s, buf, (unsigned)stored_len, 0); /* without header */ |
918 | s->compressed_len = stored_len << 3; |
919 | s->method = STORED; |
920 | } else |
921 | #endif /* STORED_FILE_OK */ |
922 | |
923 | #ifdef FORCE_STORED |
924 | if (buf != (char*)0) { /* force stored block */ |
925 | #else |
926 | if (stored_len+4 <= opt_lenb && buf != (char*)0) { |
927 | /* 4: two words for the lengths */ |
928 | #endif |
929 | /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. |
930 | * Otherwise we can't have processed more than WSIZE input bytes since |
931 | * the last block flush, because compression would have been |
932 | * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to |
933 | * transform a block into a stored block. |
934 | */ |
935 | zlib_tr_stored_block(s, buf, stored_len, eof); |
936 | |
937 | #ifdef FORCE_STATIC |
938 | } else if (static_lenb >= 0) { /* force static trees */ |
939 | #else |
940 | } else if (static_lenb == opt_lenb) { |
941 | #endif |
942 | send_bits(s, (STATIC_TREES<<1)+eof, 3); |
943 | compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree); |
944 | s->compressed_len += 3 + s->static_len; |
945 | } else { |
946 | send_bits(s, (DYN_TREES<<1)+eof, 3); |
947 | send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1, |
948 | max_blindex+1); |
949 | compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree); |
950 | s->compressed_len += 3 + s->opt_len; |
951 | } |
952 | Assert (s->compressed_len == s->bits_sent, "bad compressed size"); |
953 | init_block(s); |
954 | |
955 | if (eof) { |
956 | bi_windup(s); |
957 | s->compressed_len += 7; /* align on byte boundary */ |
958 | } |
959 | Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3, |
960 | s->compressed_len-7*eof)); |
961 | |
962 | return s->compressed_len >> 3; |
963 | } |
964 | |
965 | /* =========================================================================== |
966 | * Save the match info and tally the frequency counts. Return true if |
967 | * the current block must be flushed. |
968 | */ |
969 | int zlib_tr_tally( |
970 | deflate_state *s, |
971 | unsigned dist, /* distance of matched string */ |
972 | unsigned lc /* match length-MIN_MATCH or unmatched char (if dist==0) */ |
973 | ) |
974 | { |
975 | s->d_buf[s->last_lit] = (ush)dist; |
976 | s->l_buf[s->last_lit++] = (uch)lc; |
977 | if (dist == 0) { |
978 | /* lc is the unmatched char */ |
979 | s->dyn_ltree[lc].Freq++; |
980 | } else { |
981 | s->matches++; |
982 | /* Here, lc is the match length - MIN_MATCH */ |
983 | dist--; /* dist = match distance - 1 */ |
984 | Assert((ush)dist < (ush)MAX_DIST(s) && |
985 | (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && |
986 | (ush)d_code(dist) < (ush)D_CODES, "zlib_tr_tally: bad match"); |
987 | |
988 | s->dyn_ltree[length_code[lc]+LITERALS+1].Freq++; |
989 | s->dyn_dtree[d_code(dist)].Freq++; |
990 | } |
991 | |
992 | /* Try to guess if it is profitable to stop the current block here */ |
993 | if ((s->last_lit & 0xfff) == 0 && s->level > 2) { |
994 | /* Compute an upper bound for the compressed length */ |
995 | ulg out_length = (ulg)s->last_lit*8L; |
996 | ulg in_length = (ulg)((long)s->strstart - s->block_start); |
997 | int dcode; |
998 | for (dcode = 0; dcode < D_CODES; dcode++) { |
999 | out_length += (ulg)s->dyn_dtree[dcode].Freq * |
1000 | (5L+extra_dbits[dcode]); |
1001 | } |
1002 | out_length >>= 3; |
1003 | Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ", |
1004 | s->last_lit, in_length, out_length, |
1005 | 100L - out_length*100L/in_length)); |
1006 | if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1; |
1007 | } |
1008 | return (s->last_lit == s->lit_bufsize-1); |
1009 | /* We avoid equality with lit_bufsize because of wraparound at 64K |
1010 | * on 16 bit machines and because stored blocks are restricted to |
1011 | * 64K-1 bytes. |
1012 | */ |
1013 | } |
1014 | |
1015 | /* =========================================================================== |
1016 | * Send the block data compressed using the given Huffman trees |
1017 | */ |
1018 | static void compress_block( |
1019 | deflate_state *s, |
1020 | ct_data *ltree, /* literal tree */ |
1021 | ct_data *dtree /* distance tree */ |
1022 | ) |
1023 | { |
1024 | unsigned dist; /* distance of matched string */ |
1025 | int lc; /* match length or unmatched char (if dist == 0) */ |
1026 | unsigned lx = 0; /* running index in l_buf */ |
1027 | unsigned code; /* the code to send */ |
1028 | int extra; /* number of extra bits to send */ |
1029 | |
1030 | if (s->last_lit != 0) do { |
1031 | dist = s->d_buf[lx]; |
1032 | lc = s->l_buf[lx++]; |
1033 | if (dist == 0) { |
1034 | send_code(s, lc, ltree); /* send a literal byte */ |
1035 | Tracecv(isgraph(lc), (stderr," '%c' ", lc)); |
1036 | } else { |
1037 | /* Here, lc is the match length - MIN_MATCH */ |
1038 | code = length_code[lc]; |
1039 | send_code(s, code+LITERALS+1, ltree); /* send the length code */ |
1040 | extra = extra_lbits[code]; |
1041 | if (extra != 0) { |
1042 | lc -= base_length[code]; |
1043 | send_bits(s, lc, extra); /* send the extra length bits */ |
1044 | } |
1045 | dist--; /* dist is now the match distance - 1 */ |
1046 | code = d_code(dist); |
1047 | Assert (code < D_CODES, "bad d_code"); |
1048 | |
1049 | send_code(s, code, dtree); /* send the distance code */ |
1050 | extra = extra_dbits[code]; |
1051 | if (extra != 0) { |
1052 | dist -= base_dist[code]; |
1053 | send_bits(s, dist, extra); /* send the extra distance bits */ |
1054 | } |
1055 | } /* literal or match pair ? */ |
1056 | |
1057 | /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */ |
1058 | Assert(s->pending < s->lit_bufsize + 2*lx, "pendingBuf overflow"); |
1059 | |
1060 | } while (lx < s->last_lit); |
1061 | |
1062 | send_code(s, END_BLOCK, ltree); |
1063 | s->last_eob_len = ltree[END_BLOCK].Len; |
1064 | } |
1065 | |
1066 | /* =========================================================================== |
1067 | * Set the data type to ASCII or BINARY, using a crude approximation: |
1068 | * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise. |
1069 | * IN assertion: the fields freq of dyn_ltree are set and the total of all |
1070 | * frequencies does not exceed 64K (to fit in an int on 16 bit machines). |
1071 | */ |
1072 | static void set_data_type( |
1073 | deflate_state *s |
1074 | ) |
1075 | { |
1076 | int n = 0; |
1077 | unsigned ascii_freq = 0; |
1078 | unsigned bin_freq = 0; |
1079 | while (n < 7) bin_freq += s->dyn_ltree[n++].Freq; |
1080 | while (n < 128) ascii_freq += s->dyn_ltree[n++].Freq; |
1081 | while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq; |
1082 | s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? Z_BINARY : Z_ASCII); |
1083 | } |
1084 | |
1085 | /* =========================================================================== |
1086 | * Copy a stored block, storing first the length and its |
1087 | * one's complement if requested. |
1088 | */ |
1089 | static void copy_block( |
1090 | deflate_state *s, |
1091 | char *buf, /* the input data */ |
1092 | unsigned len, /* its length */ |
1093 | int header /* true if block header must be written */ |
1094 | ) |
1095 | { |
1096 | bi_windup(s); /* align on byte boundary */ |
1097 | s->last_eob_len = 8; /* enough lookahead for inflate */ |
1098 | |
1099 | if (header) { |
1100 | put_short(s, (ush)len); |
1101 | put_short(s, (ush)~len); |
1102 | #ifdef DEBUG_ZLIB |
1103 | s->bits_sent += 2*16; |
1104 | #endif |
1105 | } |
1106 | #ifdef DEBUG_ZLIB |
1107 | s->bits_sent += (ulg)len<<3; |
1108 | #endif |
1109 | /* bundle up the put_byte(s, *buf++) calls */ |
1110 | memcpy(&s->pending_buf[s->pending], buf, len); |
1111 | s->pending += len; |
1112 | } |
1113 | |
1114 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9