Commit | Line | Data |
---|---|---|
1da177e4 LT |
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> | |
8b235f2f | 38 | #include <linux/bitrev.h> |
1da177e4 LT |
39 | #include "defutil.h" |
40 | ||
41 | #ifdef DEBUG_ZLIB | |
42 | # include <ctype.h> | |
43 | #endif | |
44 | ||
45 | /* =========================================================================== | |
46 | * Constants | |
47 | */ | |
48 | ||
49 | #define MAX_BL_BITS 7 | |
50 | /* Bit length codes must not exceed MAX_BL_BITS bits */ | |
51 | ||
52 | #define END_BLOCK 256 | |
53 | /* end of block literal code */ | |
54 | ||
55 | #define REP_3_6 16 | |
56 | /* repeat previous bit length 3-6 times (2 bits of repeat count) */ | |
57 | ||
58 | #define REPZ_3_10 17 | |
59 | /* repeat a zero length 3-10 times (3 bits of repeat count) */ | |
60 | ||
61 | #define REPZ_11_138 18 | |
62 | /* repeat a zero length 11-138 times (7 bits of repeat count) */ | |
63 | ||
64 | static const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ | |
65 | = {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}; | |
66 | ||
67 | static const int extra_dbits[D_CODES] /* extra bits for each distance code */ | |
68 | = {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}; | |
69 | ||
70 | static const int extra_blbits[BL_CODES]/* extra bits for each bit length code */ | |
71 | = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; | |
72 | ||
73 | static const uch bl_order[BL_CODES] | |
74 | = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; | |
75 | /* The lengths of the bit length codes are sent in order of decreasing | |
76 | * probability, to avoid transmitting the lengths for unused bit length codes. | |
77 | */ | |
78 | ||
1da177e4 LT |
79 | /* =========================================================================== |
80 | * Local data. These are initialized only once. | |
81 | */ | |
82 | ||
83 | static ct_data static_ltree[L_CODES+2]; | |
84 | /* The static literal tree. Since the bit lengths are imposed, there is no | |
85 | * need for the L_CODES extra codes used during heap construction. However | |
86 | * The codes 286 and 287 are needed to build a canonical tree (see zlib_tr_init | |
87 | * below). | |
88 | */ | |
89 | ||
90 | static ct_data static_dtree[D_CODES]; | |
91 | /* The static distance tree. (Actually a trivial tree since all codes use | |
92 | * 5 bits.) | |
93 | */ | |
94 | ||
95 | static uch dist_code[512]; | |
96 | /* distance codes. The first 256 values correspond to the distances | |
97 | * 3 .. 258, the last 256 values correspond to the top 8 bits of | |
98 | * the 15 bit distances. | |
99 | */ | |
100 | ||
101 | static uch length_code[MAX_MATCH-MIN_MATCH+1]; | |
102 | /* length code for each normalized match length (0 == MIN_MATCH) */ | |
103 | ||
104 | static int base_length[LENGTH_CODES]; | |
105 | /* First normalized length for each code (0 = MIN_MATCH) */ | |
106 | ||
107 | static int base_dist[D_CODES]; | |
108 | /* First normalized distance for each code (0 = distance of 1) */ | |
109 | ||
110 | struct static_tree_desc_s { | |
111 | const ct_data *static_tree; /* static tree or NULL */ | |
112 | const int *extra_bits; /* extra bits for each code or NULL */ | |
113 | int extra_base; /* base index for extra_bits */ | |
114 | int elems; /* max number of elements in the tree */ | |
115 | int max_length; /* max bit length for the codes */ | |
116 | }; | |
117 | ||
118 | static static_tree_desc static_l_desc = | |
119 | {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; | |
120 | ||
121 | static static_tree_desc static_d_desc = | |
122 | {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; | |
123 | ||
124 | static static_tree_desc static_bl_desc = | |
125 | {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; | |
126 | ||
127 | /* =========================================================================== | |
128 | * Local (static) routines in this file. | |
129 | */ | |
130 | ||
131 | static void tr_static_init (void); | |
132 | static void init_block (deflate_state *s); | |
133 | static void pqdownheap (deflate_state *s, ct_data *tree, int k); | |
134 | static void gen_bitlen (deflate_state *s, tree_desc *desc); | |
135 | static void gen_codes (ct_data *tree, int max_code, ush *bl_count); | |
136 | static void build_tree (deflate_state *s, tree_desc *desc); | |
137 | static void scan_tree (deflate_state *s, ct_data *tree, int max_code); | |
138 | static void send_tree (deflate_state *s, ct_data *tree, int max_code); | |
139 | static int build_bl_tree (deflate_state *s); | |
140 | static void send_all_trees (deflate_state *s, int lcodes, int dcodes, | |
141 | int blcodes); | |
142 | static void compress_block (deflate_state *s, ct_data *ltree, | |
143 | ct_data *dtree); | |
144 | static void set_data_type (deflate_state *s); | |
1da177e4 LT |
145 | static void bi_flush (deflate_state *s); |
146 | static void copy_block (deflate_state *s, char *buf, unsigned len, | |
147 | int header); | |
148 | ||
149 | #ifndef DEBUG_ZLIB | |
150 | # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len) | |
151 | /* Send a code of the given tree. c and tree must not have side effects */ | |
152 | ||
153 | #else /* DEBUG_ZLIB */ | |
154 | # define send_code(s, c, tree) \ | |
155 | { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \ | |
156 | send_bits(s, tree[c].Code, tree[c].Len); } | |
157 | #endif | |
158 | ||
159 | #define d_code(dist) \ | |
160 | ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)]) | |
161 | /* Mapping from a distance to a distance code. dist is the distance - 1 and | |
162 | * must not have side effects. dist_code[256] and dist_code[257] are never | |
163 | * used. | |
164 | */ | |
165 | ||
1da177e4 LT |
166 | /* =========================================================================== |
167 | * Initialize the various 'constant' tables. In a multi-threaded environment, | |
168 | * this function may be called by two threads concurrently, but this is | |
169 | * harmless since both invocations do exactly the same thing. | |
170 | */ | |
171 | static void tr_static_init(void) | |
172 | { | |
173 | static int static_init_done; | |
174 | int n; /* iterates over tree elements */ | |
175 | int bits; /* bit counter */ | |
176 | int length; /* length value */ | |
177 | int code; /* code value */ | |
178 | int dist; /* distance index */ | |
179 | ush bl_count[MAX_BITS+1]; | |
180 | /* number of codes at each bit length for an optimal tree */ | |
181 | ||
182 | if (static_init_done) return; | |
183 | ||
184 | /* Initialize the mapping length (0..255) -> length code (0..28) */ | |
185 | length = 0; | |
186 | for (code = 0; code < LENGTH_CODES-1; code++) { | |
187 | base_length[code] = length; | |
188 | for (n = 0; n < (1<<extra_lbits[code]); n++) { | |
189 | length_code[length++] = (uch)code; | |
190 | } | |
191 | } | |
192 | Assert (length == 256, "tr_static_init: length != 256"); | |
193 | /* Note that the length 255 (match length 258) can be represented | |
194 | * in two different ways: code 284 + 5 bits or code 285, so we | |
195 | * overwrite length_code[255] to use the best encoding: | |
196 | */ | |
197 | length_code[length-1] = (uch)code; | |
198 | ||
199 | /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ | |
200 | dist = 0; | |
201 | for (code = 0 ; code < 16; code++) { | |
202 | base_dist[code] = dist; | |
203 | for (n = 0; n < (1<<extra_dbits[code]); n++) { | |
204 | dist_code[dist++] = (uch)code; | |
205 | } | |
206 | } | |
207 | Assert (dist == 256, "tr_static_init: dist != 256"); | |
208 | dist >>= 7; /* from now on, all distances are divided by 128 */ | |
209 | for ( ; code < D_CODES; code++) { | |
210 | base_dist[code] = dist << 7; | |
211 | for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { | |
212 | dist_code[256 + dist++] = (uch)code; | |
213 | } | |
214 | } | |
215 | Assert (dist == 256, "tr_static_init: 256+dist != 512"); | |
216 | ||
217 | /* Construct the codes of the static literal tree */ | |
218 | for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; | |
219 | n = 0; | |
220 | while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; | |
221 | while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; | |
222 | while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; | |
223 | while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; | |
224 | /* Codes 286 and 287 do not exist, but we must include them in the | |
225 | * tree construction to get a canonical Huffman tree (longest code | |
226 | * all ones) | |
227 | */ | |
228 | gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count); | |
229 | ||
230 | /* The static distance tree is trivial: */ | |
231 | for (n = 0; n < D_CODES; n++) { | |
232 | static_dtree[n].Len = 5; | |
8b235f2f | 233 | static_dtree[n].Code = bitrev32((u32)n) >> (32 - 5); |
1da177e4 LT |
234 | } |
235 | static_init_done = 1; | |
236 | } | |
237 | ||
238 | /* =========================================================================== | |
239 | * Initialize the tree data structures for a new zlib stream. | |
240 | */ | |
241 | void zlib_tr_init( | |
242 | deflate_state *s | |
243 | ) | |
244 | { | |
245 | tr_static_init(); | |
246 | ||
247 | s->compressed_len = 0L; | |
248 | ||
249 | s->l_desc.dyn_tree = s->dyn_ltree; | |
250 | s->l_desc.stat_desc = &static_l_desc; | |
251 | ||
252 | s->d_desc.dyn_tree = s->dyn_dtree; | |
253 | s->d_desc.stat_desc = &static_d_desc; | |
254 | ||
255 | s->bl_desc.dyn_tree = s->bl_tree; | |
256 | s->bl_desc.stat_desc = &static_bl_desc; | |
257 | ||
258 | s->bi_buf = 0; | |
259 | s->bi_valid = 0; | |
260 | s->last_eob_len = 8; /* enough lookahead for inflate */ | |
261 | #ifdef DEBUG_ZLIB | |
262 | s->bits_sent = 0L; | |
263 | #endif | |
264 | ||
265 | /* Initialize the first block of the first file: */ | |
266 | init_block(s); | |
267 | } | |
268 | ||
269 | /* =========================================================================== | |
270 | * Initialize a new block. | |
271 | */ | |
272 | static void init_block( | |
273 | deflate_state *s | |
274 | ) | |
275 | { | |
276 | int n; /* iterates over tree elements */ | |
277 | ||
278 | /* Initialize the trees. */ | |
279 | for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0; | |
280 | for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0; | |
281 | for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0; | |
282 | ||
283 | s->dyn_ltree[END_BLOCK].Freq = 1; | |
284 | s->opt_len = s->static_len = 0L; | |
285 | s->last_lit = s->matches = 0; | |
286 | } | |
287 | ||
288 | #define SMALLEST 1 | |
289 | /* Index within the heap array of least frequent node in the Huffman tree */ | |
290 | ||
291 | ||
292 | /* =========================================================================== | |
293 | * Remove the smallest element from the heap and recreate the heap with | |
294 | * one less element. Updates heap and heap_len. | |
295 | */ | |
296 | #define pqremove(s, tree, top) \ | |
297 | {\ | |
298 | top = s->heap[SMALLEST]; \ | |
299 | s->heap[SMALLEST] = s->heap[s->heap_len--]; \ | |
300 | pqdownheap(s, tree, SMALLEST); \ | |
301 | } | |
302 | ||
303 | /* =========================================================================== | |
304 | * Compares to subtrees, using the tree depth as tie breaker when | |
305 | * the subtrees have equal frequency. This minimizes the worst case length. | |
306 | */ | |
307 | #define smaller(tree, n, m, depth) \ | |
308 | (tree[n].Freq < tree[m].Freq || \ | |
309 | (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) | |
310 | ||
311 | /* =========================================================================== | |
312 | * Restore the heap property by moving down the tree starting at node k, | |
313 | * exchanging a node with the smallest of its two sons if necessary, stopping | |
314 | * when the heap property is re-established (each father smaller than its | |
315 | * two sons). | |
316 | */ | |
317 | static void pqdownheap( | |
318 | deflate_state *s, | |
319 | ct_data *tree, /* the tree to restore */ | |
320 | int k /* node to move down */ | |
321 | ) | |
322 | { | |
323 | int v = s->heap[k]; | |
324 | int j = k << 1; /* left son of k */ | |
325 | while (j <= s->heap_len) { | |
326 | /* Set j to the smallest of the two sons: */ | |
327 | if (j < s->heap_len && | |
328 | smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { | |
329 | j++; | |
330 | } | |
331 | /* Exit if v is smaller than both sons */ | |
332 | if (smaller(tree, v, s->heap[j], s->depth)) break; | |
333 | ||
334 | /* Exchange v with the smallest son */ | |
335 | s->heap[k] = s->heap[j]; k = j; | |
336 | ||
337 | /* And continue down the tree, setting j to the left son of k */ | |
338 | j <<= 1; | |
339 | } | |
340 | s->heap[k] = v; | |
341 | } | |
342 | ||
343 | /* =========================================================================== | |
344 | * Compute the optimal bit lengths for a tree and update the total bit length | |
345 | * for the current block. | |
346 | * IN assertion: the fields freq and dad are set, heap[heap_max] and | |
347 | * above are the tree nodes sorted by increasing frequency. | |
348 | * OUT assertions: the field len is set to the optimal bit length, the | |
349 | * array bl_count contains the frequencies for each bit length. | |
350 | * The length opt_len is updated; static_len is also updated if stree is | |
351 | * not null. | |
352 | */ | |
353 | static void gen_bitlen( | |
354 | deflate_state *s, | |
355 | tree_desc *desc /* the tree descriptor */ | |
356 | ) | |
357 | { | |
358 | ct_data *tree = desc->dyn_tree; | |
359 | int max_code = desc->max_code; | |
360 | const ct_data *stree = desc->stat_desc->static_tree; | |
361 | const int *extra = desc->stat_desc->extra_bits; | |
362 | int base = desc->stat_desc->extra_base; | |
363 | int max_length = desc->stat_desc->max_length; | |
364 | int h; /* heap index */ | |
365 | int n, m; /* iterate over the tree elements */ | |
366 | int bits; /* bit length */ | |
367 | int xbits; /* extra bits */ | |
368 | ush f; /* frequency */ | |
369 | int overflow = 0; /* number of elements with bit length too large */ | |
370 | ||
371 | for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0; | |
372 | ||
373 | /* In a first pass, compute the optimal bit lengths (which may | |
374 | * overflow in the case of the bit length tree). | |
375 | */ | |
376 | tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ | |
377 | ||
378 | for (h = s->heap_max+1; h < HEAP_SIZE; h++) { | |
379 | n = s->heap[h]; | |
380 | bits = tree[tree[n].Dad].Len + 1; | |
381 | if (bits > max_length) bits = max_length, overflow++; | |
382 | tree[n].Len = (ush)bits; | |
383 | /* We overwrite tree[n].Dad which is no longer needed */ | |
384 | ||
385 | if (n > max_code) continue; /* not a leaf node */ | |
386 | ||
387 | s->bl_count[bits]++; | |
388 | xbits = 0; | |
389 | if (n >= base) xbits = extra[n-base]; | |
390 | f = tree[n].Freq; | |
391 | s->opt_len += (ulg)f * (bits + xbits); | |
392 | if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits); | |
393 | } | |
394 | if (overflow == 0) return; | |
395 | ||
396 | Trace((stderr,"\nbit length overflow\n")); | |
397 | /* This happens for example on obj2 and pic of the Calgary corpus */ | |
398 | ||
399 | /* Find the first bit length which could increase: */ | |
400 | do { | |
401 | bits = max_length-1; | |
402 | while (s->bl_count[bits] == 0) bits--; | |
403 | s->bl_count[bits]--; /* move one leaf down the tree */ | |
404 | s->bl_count[bits+1] += 2; /* move one overflow item as its brother */ | |
405 | s->bl_count[max_length]--; | |
406 | /* The brother of the overflow item also moves one step up, | |
407 | * but this does not affect bl_count[max_length] | |
408 | */ | |
409 | overflow -= 2; | |
410 | } while (overflow > 0); | |
411 | ||
412 | /* Now recompute all bit lengths, scanning in increasing frequency. | |
413 | * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all | |
414 | * lengths instead of fixing only the wrong ones. This idea is taken | |
415 | * from 'ar' written by Haruhiko Okumura.) | |
416 | */ | |
417 | for (bits = max_length; bits != 0; bits--) { | |
418 | n = s->bl_count[bits]; | |
419 | while (n != 0) { | |
420 | m = s->heap[--h]; | |
421 | if (m > max_code) continue; | |
422 | if (tree[m].Len != (unsigned) bits) { | |
423 | Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); | |
424 | s->opt_len += ((long)bits - (long)tree[m].Len) | |
425 | *(long)tree[m].Freq; | |
426 | tree[m].Len = (ush)bits; | |
427 | } | |
428 | n--; | |
429 | } | |
430 | } | |
431 | } | |
432 | ||
433 | /* =========================================================================== | |
434 | * Generate the codes for a given tree and bit counts (which need not be | |
435 | * optimal). | |
436 | * IN assertion: the array bl_count contains the bit length statistics for | |
437 | * the given tree and the field len is set for all tree elements. | |
438 | * OUT assertion: the field code is set for all tree elements of non | |
439 | * zero code length. | |
440 | */ | |
441 | static void gen_codes( | |
442 | ct_data *tree, /* the tree to decorate */ | |
443 | int max_code, /* largest code with non zero frequency */ | |
444 | ush *bl_count /* number of codes at each bit length */ | |
445 | ) | |
446 | { | |
447 | ush next_code[MAX_BITS+1]; /* next code value for each bit length */ | |
448 | ush code = 0; /* running code value */ | |
449 | int bits; /* bit index */ | |
450 | int n; /* code index */ | |
451 | ||
452 | /* The distribution counts are first used to generate the code values | |
453 | * without bit reversal. | |
454 | */ | |
455 | for (bits = 1; bits <= MAX_BITS; bits++) { | |
456 | next_code[bits] = code = (code + bl_count[bits-1]) << 1; | |
457 | } | |
458 | /* Check that the bit counts in bl_count are consistent. The last code | |
459 | * must be all ones. | |
460 | */ | |
461 | Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, | |
462 | "inconsistent bit counts"); | |
463 | Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); | |
464 | ||
465 | for (n = 0; n <= max_code; n++) { | |
466 | int len = tree[n].Len; | |
467 | if (len == 0) continue; | |
468 | /* Now reverse the bits */ | |
8b235f2f | 469 | tree[n].Code = bitrev32((u32)(next_code[len]++)) >> (32 - len); |
1da177e4 LT |
470 | |
471 | Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", | |
472 | n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); | |
473 | } | |
474 | } | |
475 | ||
476 | /* =========================================================================== | |
477 | * Construct one Huffman tree and assigns the code bit strings and lengths. | |
478 | * Update the total bit length for the current block. | |
479 | * IN assertion: the field freq is set for all tree elements. | |
480 | * OUT assertions: the fields len and code are set to the optimal bit length | |
481 | * and corresponding code. The length opt_len is updated; static_len is | |
482 | * also updated if stree is not null. The field max_code is set. | |
483 | */ | |
484 | static void build_tree( | |
485 | deflate_state *s, | |
486 | tree_desc *desc /* the tree descriptor */ | |
487 | ) | |
488 | { | |
489 | ct_data *tree = desc->dyn_tree; | |
490 | const ct_data *stree = desc->stat_desc->static_tree; | |
491 | int elems = desc->stat_desc->elems; | |
492 | int n, m; /* iterate over heap elements */ | |
493 | int max_code = -1; /* largest code with non zero frequency */ | |
494 | int node; /* new node being created */ | |
495 | ||
496 | /* Construct the initial heap, with least frequent element in | |
497 | * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. | |
498 | * heap[0] is not used. | |
499 | */ | |
500 | s->heap_len = 0, s->heap_max = HEAP_SIZE; | |
501 | ||
502 | for (n = 0; n < elems; n++) { | |
503 | if (tree[n].Freq != 0) { | |
504 | s->heap[++(s->heap_len)] = max_code = n; | |
505 | s->depth[n] = 0; | |
506 | } else { | |
507 | tree[n].Len = 0; | |
508 | } | |
509 | } | |
510 | ||
511 | /* The pkzip format requires that at least one distance code exists, | |
512 | * and that at least one bit should be sent even if there is only one | |
513 | * possible code. So to avoid special checks later on we force at least | |
514 | * two codes of non zero frequency. | |
515 | */ | |
516 | while (s->heap_len < 2) { | |
517 | node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0); | |
518 | tree[node].Freq = 1; | |
519 | s->depth[node] = 0; | |
520 | s->opt_len--; if (stree) s->static_len -= stree[node].Len; | |
521 | /* node is 0 or 1 so it does not have extra bits */ | |
522 | } | |
523 | desc->max_code = max_code; | |
524 | ||
525 | /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, | |
526 | * establish sub-heaps of increasing lengths: | |
527 | */ | |
528 | for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n); | |
529 | ||
530 | /* Construct the Huffman tree by repeatedly combining the least two | |
531 | * frequent nodes. | |
532 | */ | |
533 | node = elems; /* next internal node of the tree */ | |
534 | do { | |
535 | pqremove(s, tree, n); /* n = node of least frequency */ | |
536 | m = s->heap[SMALLEST]; /* m = node of next least frequency */ | |
537 | ||
538 | s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */ | |
539 | s->heap[--(s->heap_max)] = m; | |
540 | ||
541 | /* Create a new node father of n and m */ | |
542 | tree[node].Freq = tree[n].Freq + tree[m].Freq; | |
543 | s->depth[node] = (uch) (max(s->depth[n], s->depth[m]) + 1); | |
544 | tree[n].Dad = tree[m].Dad = (ush)node; | |
545 | #ifdef DUMP_BL_TREE | |
546 | if (tree == s->bl_tree) { | |
547 | fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", | |
548 | node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); | |
549 | } | |
550 | #endif | |
551 | /* and insert the new node in the heap */ | |
552 | s->heap[SMALLEST] = node++; | |
553 | pqdownheap(s, tree, SMALLEST); | |
554 | ||
555 | } while (s->heap_len >= 2); | |
556 | ||
557 | s->heap[--(s->heap_max)] = s->heap[SMALLEST]; | |
558 | ||
559 | /* At this point, the fields freq and dad are set. We can now | |
560 | * generate the bit lengths. | |
561 | */ | |
562 | gen_bitlen(s, (tree_desc *)desc); | |
563 | ||
564 | /* The field len is now set, we can generate the bit codes */ | |
565 | gen_codes ((ct_data *)tree, max_code, s->bl_count); | |
566 | } | |
567 | ||
568 | /* =========================================================================== | |
569 | * Scan a literal or distance tree to determine the frequencies of the codes | |
570 | * in the bit length tree. | |
571 | */ | |
572 | static void scan_tree( | |
573 | deflate_state *s, | |
574 | ct_data *tree, /* the tree to be scanned */ | |
575 | int max_code /* and its largest code of non zero frequency */ | |
576 | ) | |
577 | { | |
578 | int n; /* iterates over all tree elements */ | |
579 | int prevlen = -1; /* last emitted length */ | |
580 | int curlen; /* length of current code */ | |
581 | int nextlen = tree[0].Len; /* length of next code */ | |
582 | int count = 0; /* repeat count of the current code */ | |
583 | int max_count = 7; /* max repeat count */ | |
584 | int min_count = 4; /* min repeat count */ | |
585 | ||
586 | if (nextlen == 0) max_count = 138, min_count = 3; | |
587 | tree[max_code+1].Len = (ush)0xffff; /* guard */ | |
588 | ||
589 | for (n = 0; n <= max_code; n++) { | |
590 | curlen = nextlen; nextlen = tree[n+1].Len; | |
591 | if (++count < max_count && curlen == nextlen) { | |
592 | continue; | |
593 | } else if (count < min_count) { | |
594 | s->bl_tree[curlen].Freq += count; | |
595 | } else if (curlen != 0) { | |
596 | if (curlen != prevlen) s->bl_tree[curlen].Freq++; | |
597 | s->bl_tree[REP_3_6].Freq++; | |
598 | } else if (count <= 10) { | |
599 | s->bl_tree[REPZ_3_10].Freq++; | |
600 | } else { | |
601 | s->bl_tree[REPZ_11_138].Freq++; | |
602 | } | |
603 | count = 0; prevlen = curlen; | |
604 | if (nextlen == 0) { | |
605 | max_count = 138, min_count = 3; | |
606 | } else if (curlen == nextlen) { | |
607 | max_count = 6, min_count = 3; | |
608 | } else { | |
609 | max_count = 7, min_count = 4; | |
610 | } | |
611 | } | |
612 | } | |
613 | ||
614 | /* =========================================================================== | |
615 | * Send a literal or distance tree in compressed form, using the codes in | |
616 | * bl_tree. | |
617 | */ | |
618 | static void send_tree( | |
619 | deflate_state *s, | |
620 | ct_data *tree, /* the tree to be scanned */ | |
621 | int max_code /* and its largest code of non zero frequency */ | |
622 | ) | |
623 | { | |
624 | int n; /* iterates over all tree elements */ | |
625 | int prevlen = -1; /* last emitted length */ | |
626 | int curlen; /* length of current code */ | |
627 | int nextlen = tree[0].Len; /* length of next code */ | |
628 | int count = 0; /* repeat count of the current code */ | |
629 | int max_count = 7; /* max repeat count */ | |
630 | int min_count = 4; /* min repeat count */ | |
631 | ||
632 | /* tree[max_code+1].Len = -1; */ /* guard already set */ | |
633 | if (nextlen == 0) max_count = 138, min_count = 3; | |
634 | ||
635 | for (n = 0; n <= max_code; n++) { | |
636 | curlen = nextlen; nextlen = tree[n+1].Len; | |
637 | if (++count < max_count && curlen == nextlen) { | |
638 | continue; | |
639 | } else if (count < min_count) { | |
640 | do { send_code(s, curlen, s->bl_tree); } while (--count != 0); | |
641 | ||
642 | } else if (curlen != 0) { | |
643 | if (curlen != prevlen) { | |
644 | send_code(s, curlen, s->bl_tree); count--; | |
645 | } | |
646 | Assert(count >= 3 && count <= 6, " 3_6?"); | |
647 | send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2); | |
648 | ||
649 | } else if (count <= 10) { | |
650 | send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3); | |
651 | ||
652 | } else { | |
653 | send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7); | |
654 | } | |
655 | count = 0; prevlen = curlen; | |
656 | if (nextlen == 0) { | |
657 | max_count = 138, min_count = 3; | |
658 | } else if (curlen == nextlen) { | |
659 | max_count = 6, min_count = 3; | |
660 | } else { | |
661 | max_count = 7, min_count = 4; | |
662 | } | |
663 | } | |
664 | } | |
665 | ||
666 | /* =========================================================================== | |
667 | * Construct the Huffman tree for the bit lengths and return the index in | |
668 | * bl_order of the last bit length code to send. | |
669 | */ | |
670 | static int build_bl_tree( | |
671 | deflate_state *s | |
672 | ) | |
673 | { | |
674 | int max_blindex; /* index of last bit length code of non zero freq */ | |
675 | ||
676 | /* Determine the bit length frequencies for literal and distance trees */ | |
677 | scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code); | |
678 | scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code); | |
679 | ||
680 | /* Build the bit length tree: */ | |
681 | build_tree(s, (tree_desc *)(&(s->bl_desc))); | |
682 | /* opt_len now includes the length of the tree representations, except | |
683 | * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. | |
684 | */ | |
685 | ||
686 | /* Determine the number of bit length codes to send. The pkzip format | |
687 | * requires that at least 4 bit length codes be sent. (appnote.txt says | |
688 | * 3 but the actual value used is 4.) | |
689 | */ | |
690 | for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { | |
691 | if (s->bl_tree[bl_order[max_blindex]].Len != 0) break; | |
692 | } | |
693 | /* Update opt_len to include the bit length tree and counts */ | |
694 | s->opt_len += 3*(max_blindex+1) + 5+5+4; | |
695 | Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", | |
696 | s->opt_len, s->static_len)); | |
697 | ||
698 | return max_blindex; | |
699 | } | |
700 | ||
701 | /* =========================================================================== | |
702 | * Send the header for a block using dynamic Huffman trees: the counts, the | |
703 | * lengths of the bit length codes, the literal tree and the distance tree. | |
704 | * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. | |
705 | */ | |
706 | static void send_all_trees( | |
707 | deflate_state *s, | |
708 | int lcodes, /* number of codes for each tree */ | |
709 | int dcodes, /* number of codes for each tree */ | |
710 | int blcodes /* number of codes for each tree */ | |
711 | ) | |
712 | { | |
713 | int rank; /* index in bl_order */ | |
714 | ||
715 | Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); | |
716 | Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, | |
717 | "too many codes"); | |
718 | Tracev((stderr, "\nbl counts: ")); | |
719 | send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */ | |
720 | send_bits(s, dcodes-1, 5); | |
721 | send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */ | |
722 | for (rank = 0; rank < blcodes; rank++) { | |
723 | Tracev((stderr, "\nbl code %2d ", bl_order[rank])); | |
724 | send_bits(s, s->bl_tree[bl_order[rank]].Len, 3); | |
725 | } | |
726 | Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent)); | |
727 | ||
728 | send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */ | |
729 | Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent)); | |
730 | ||
731 | send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */ | |
732 | Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent)); | |
733 | } | |
734 | ||
735 | /* =========================================================================== | |
736 | * Send a stored block | |
737 | */ | |
738 | void zlib_tr_stored_block( | |
739 | deflate_state *s, | |
740 | char *buf, /* input block */ | |
741 | ulg stored_len, /* length of input block */ | |
742 | int eof /* true if this is the last block for a file */ | |
743 | ) | |
744 | { | |
745 | send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */ | |
746 | s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L; | |
747 | s->compressed_len += (stored_len + 4) << 3; | |
748 | ||
749 | copy_block(s, buf, (unsigned)stored_len, 1); /* with header */ | |
750 | } | |
751 | ||
752 | /* Send just the `stored block' type code without any length bytes or data. | |
753 | */ | |
754 | void zlib_tr_stored_type_only( | |
755 | deflate_state *s | |
756 | ) | |
757 | { | |
758 | send_bits(s, (STORED_BLOCK << 1), 3); | |
759 | bi_windup(s); | |
760 | s->compressed_len = (s->compressed_len + 3) & ~7L; | |
761 | } | |
762 | ||
763 | ||
764 | /* =========================================================================== | |
765 | * Send one empty static block to give enough lookahead for inflate. | |
766 | * This takes 10 bits, of which 7 may remain in the bit buffer. | |
767 | * The current inflate code requires 9 bits of lookahead. If the | |
768 | * last two codes for the previous block (real code plus EOB) were coded | |
769 | * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode | |
770 | * the last real code. In this case we send two empty static blocks instead | |
771 | * of one. (There are no problems if the previous block is stored or fixed.) | |
772 | * To simplify the code, we assume the worst case of last real code encoded | |
773 | * on one bit only. | |
774 | */ | |
775 | void zlib_tr_align( | |
776 | deflate_state *s | |
777 | ) | |
778 | { | |
779 | send_bits(s, STATIC_TREES<<1, 3); | |
780 | send_code(s, END_BLOCK, static_ltree); | |
781 | s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ | |
782 | bi_flush(s); | |
783 | /* Of the 10 bits for the empty block, we have already sent | |
784 | * (10 - bi_valid) bits. The lookahead for the last real code (before | |
785 | * the EOB of the previous block) was thus at least one plus the length | |
786 | * of the EOB plus what we have just sent of the empty static block. | |
787 | */ | |
788 | if (1 + s->last_eob_len + 10 - s->bi_valid < 9) { | |
789 | send_bits(s, STATIC_TREES<<1, 3); | |
790 | send_code(s, END_BLOCK, static_ltree); | |
791 | s->compressed_len += 10L; | |
792 | bi_flush(s); | |
793 | } | |
794 | s->last_eob_len = 7; | |
795 | } | |
796 | ||
797 | /* =========================================================================== | |
798 | * Determine the best encoding for the current block: dynamic trees, static | |
799 | * trees or store, and output the encoded block to the zip file. This function | |
800 | * returns the total compressed length for the file so far. | |
801 | */ | |
802 | ulg zlib_tr_flush_block( | |
803 | deflate_state *s, | |
804 | char *buf, /* input block, or NULL if too old */ | |
805 | ulg stored_len, /* length of input block */ | |
806 | int eof /* true if this is the last block for a file */ | |
807 | ) | |
808 | { | |
809 | ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ | |
810 | int max_blindex = 0; /* index of last bit length code of non zero freq */ | |
811 | ||
812 | /* Build the Huffman trees unless a stored block is forced */ | |
813 | if (s->level > 0) { | |
814 | ||
815 | /* Check if the file is ascii or binary */ | |
816 | if (s->data_type == Z_UNKNOWN) set_data_type(s); | |
817 | ||
818 | /* Construct the literal and distance trees */ | |
819 | build_tree(s, (tree_desc *)(&(s->l_desc))); | |
820 | Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len, | |
821 | s->static_len)); | |
822 | ||
823 | build_tree(s, (tree_desc *)(&(s->d_desc))); | |
824 | Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len, | |
825 | s->static_len)); | |
826 | /* At this point, opt_len and static_len are the total bit lengths of | |
827 | * the compressed block data, excluding the tree representations. | |
828 | */ | |
829 | ||
830 | /* Build the bit length tree for the above two trees, and get the index | |
831 | * in bl_order of the last bit length code to send. | |
832 | */ | |
833 | max_blindex = build_bl_tree(s); | |
834 | ||
835 | /* Determine the best encoding. Compute first the block length in bytes*/ | |
836 | opt_lenb = (s->opt_len+3+7)>>3; | |
837 | static_lenb = (s->static_len+3+7)>>3; | |
838 | ||
839 | Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ", | |
840 | opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, | |
841 | s->last_lit)); | |
842 | ||
843 | if (static_lenb <= opt_lenb) opt_lenb = static_lenb; | |
844 | ||
845 | } else { | |
846 | Assert(buf != (char*)0, "lost buf"); | |
847 | opt_lenb = static_lenb = stored_len + 5; /* force a stored block */ | |
848 | } | |
849 | ||
850 | /* If compression failed and this is the first and last block, | |
851 | * and if the .zip file can be seeked (to rewrite the local header), | |
852 | * the whole file is transformed into a stored file: | |
853 | */ | |
854 | #ifdef STORED_FILE_OK | |
855 | # ifdef FORCE_STORED_FILE | |
856 | if (eof && s->compressed_len == 0L) { /* force stored file */ | |
857 | # else | |
858 | if (stored_len <= opt_lenb && eof && s->compressed_len==0L && seekable()) { | |
859 | # endif | |
860 | /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ | |
861 | if (buf == (char*)0) error ("block vanished"); | |
862 | ||
863 | copy_block(s, buf, (unsigned)stored_len, 0); /* without header */ | |
864 | s->compressed_len = stored_len << 3; | |
865 | s->method = STORED; | |
866 | } else | |
867 | #endif /* STORED_FILE_OK */ | |
868 | ||
869 | #ifdef FORCE_STORED | |
870 | if (buf != (char*)0) { /* force stored block */ | |
871 | #else | |
872 | if (stored_len+4 <= opt_lenb && buf != (char*)0) { | |
873 | /* 4: two words for the lengths */ | |
874 | #endif | |
875 | /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. | |
876 | * Otherwise we can't have processed more than WSIZE input bytes since | |
877 | * the last block flush, because compression would have been | |
878 | * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to | |
879 | * transform a block into a stored block. | |
880 | */ | |
881 | zlib_tr_stored_block(s, buf, stored_len, eof); | |
882 | ||
883 | #ifdef FORCE_STATIC | |
884 | } else if (static_lenb >= 0) { /* force static trees */ | |
885 | #else | |
886 | } else if (static_lenb == opt_lenb) { | |
887 | #endif | |
888 | send_bits(s, (STATIC_TREES<<1)+eof, 3); | |
889 | compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree); | |
890 | s->compressed_len += 3 + s->static_len; | |
891 | } else { | |
892 | send_bits(s, (DYN_TREES<<1)+eof, 3); | |
893 | send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1, | |
894 | max_blindex+1); | |
895 | compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree); | |
896 | s->compressed_len += 3 + s->opt_len; | |
897 | } | |
898 | Assert (s->compressed_len == s->bits_sent, "bad compressed size"); | |
899 | init_block(s); | |
900 | ||
901 | if (eof) { | |
902 | bi_windup(s); | |
903 | s->compressed_len += 7; /* align on byte boundary */ | |
904 | } | |
905 | Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3, | |
906 | s->compressed_len-7*eof)); | |
907 | ||
908 | return s->compressed_len >> 3; | |
909 | } | |
910 | ||
911 | /* =========================================================================== | |
912 | * Save the match info and tally the frequency counts. Return true if | |
913 | * the current block must be flushed. | |
914 | */ | |
915 | int zlib_tr_tally( | |
916 | deflate_state *s, | |
917 | unsigned dist, /* distance of matched string */ | |
918 | unsigned lc /* match length-MIN_MATCH or unmatched char (if dist==0) */ | |
919 | ) | |
920 | { | |
921 | s->d_buf[s->last_lit] = (ush)dist; | |
922 | s->l_buf[s->last_lit++] = (uch)lc; | |
923 | if (dist == 0) { | |
924 | /* lc is the unmatched char */ | |
925 | s->dyn_ltree[lc].Freq++; | |
926 | } else { | |
927 | s->matches++; | |
928 | /* Here, lc is the match length - MIN_MATCH */ | |
929 | dist--; /* dist = match distance - 1 */ | |
930 | Assert((ush)dist < (ush)MAX_DIST(s) && | |
931 | (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && | |
932 | (ush)d_code(dist) < (ush)D_CODES, "zlib_tr_tally: bad match"); | |
933 | ||
934 | s->dyn_ltree[length_code[lc]+LITERALS+1].Freq++; | |
935 | s->dyn_dtree[d_code(dist)].Freq++; | |
936 | } | |
937 | ||
938 | /* Try to guess if it is profitable to stop the current block here */ | |
939 | if ((s->last_lit & 0xfff) == 0 && s->level > 2) { | |
940 | /* Compute an upper bound for the compressed length */ | |
941 | ulg out_length = (ulg)s->last_lit*8L; | |
942 | ulg in_length = (ulg)((long)s->strstart - s->block_start); | |
943 | int dcode; | |
944 | for (dcode = 0; dcode < D_CODES; dcode++) { | |
945 | out_length += (ulg)s->dyn_dtree[dcode].Freq * | |
946 | (5L+extra_dbits[dcode]); | |
947 | } | |
948 | out_length >>= 3; | |
949 | Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ", | |
950 | s->last_lit, in_length, out_length, | |
951 | 100L - out_length*100L/in_length)); | |
952 | if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1; | |
953 | } | |
954 | return (s->last_lit == s->lit_bufsize-1); | |
955 | /* We avoid equality with lit_bufsize because of wraparound at 64K | |
956 | * on 16 bit machines and because stored blocks are restricted to | |
957 | * 64K-1 bytes. | |
958 | */ | |
959 | } | |
960 | ||
961 | /* =========================================================================== | |
962 | * Send the block data compressed using the given Huffman trees | |
963 | */ | |
964 | static void compress_block( | |
965 | deflate_state *s, | |
966 | ct_data *ltree, /* literal tree */ | |
967 | ct_data *dtree /* distance tree */ | |
968 | ) | |
969 | { | |
970 | unsigned dist; /* distance of matched string */ | |
971 | int lc; /* match length or unmatched char (if dist == 0) */ | |
972 | unsigned lx = 0; /* running index in l_buf */ | |
973 | unsigned code; /* the code to send */ | |
974 | int extra; /* number of extra bits to send */ | |
975 | ||
976 | if (s->last_lit != 0) do { | |
977 | dist = s->d_buf[lx]; | |
978 | lc = s->l_buf[lx++]; | |
979 | if (dist == 0) { | |
980 | send_code(s, lc, ltree); /* send a literal byte */ | |
981 | Tracecv(isgraph(lc), (stderr," '%c' ", lc)); | |
982 | } else { | |
983 | /* Here, lc is the match length - MIN_MATCH */ | |
984 | code = length_code[lc]; | |
985 | send_code(s, code+LITERALS+1, ltree); /* send the length code */ | |
986 | extra = extra_lbits[code]; | |
987 | if (extra != 0) { | |
988 | lc -= base_length[code]; | |
989 | send_bits(s, lc, extra); /* send the extra length bits */ | |
990 | } | |
991 | dist--; /* dist is now the match distance - 1 */ | |
992 | code = d_code(dist); | |
993 | Assert (code < D_CODES, "bad d_code"); | |
994 | ||
995 | send_code(s, code, dtree); /* send the distance code */ | |
996 | extra = extra_dbits[code]; | |
997 | if (extra != 0) { | |
998 | dist -= base_dist[code]; | |
999 | send_bits(s, dist, extra); /* send the extra distance bits */ | |
1000 | } | |
1001 | } /* literal or match pair ? */ | |
1002 | ||
1003 | /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */ | |
1004 | Assert(s->pending < s->lit_bufsize + 2*lx, "pendingBuf overflow"); | |
1005 | ||
1006 | } while (lx < s->last_lit); | |
1007 | ||
1008 | send_code(s, END_BLOCK, ltree); | |
1009 | s->last_eob_len = ltree[END_BLOCK].Len; | |
1010 | } | |
1011 | ||
1012 | /* =========================================================================== | |
1013 | * Set the data type to ASCII or BINARY, using a crude approximation: | |
1014 | * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise. | |
1015 | * IN assertion: the fields freq of dyn_ltree are set and the total of all | |
1016 | * frequencies does not exceed 64K (to fit in an int on 16 bit machines). | |
1017 | */ | |
1018 | static void set_data_type( | |
1019 | deflate_state *s | |
1020 | ) | |
1021 | { | |
1022 | int n = 0; | |
1023 | unsigned ascii_freq = 0; | |
1024 | unsigned bin_freq = 0; | |
1025 | while (n < 7) bin_freq += s->dyn_ltree[n++].Freq; | |
1026 | while (n < 128) ascii_freq += s->dyn_ltree[n++].Freq; | |
1027 | while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq; | |
1028 | s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? Z_BINARY : Z_ASCII); | |
1029 | } | |
1030 | ||
1031 | /* =========================================================================== | |
1032 | * Copy a stored block, storing first the length and its | |
1033 | * one's complement if requested. | |
1034 | */ | |
1035 | static void copy_block( | |
1036 | deflate_state *s, | |
1037 | char *buf, /* the input data */ | |
1038 | unsigned len, /* its length */ | |
1039 | int header /* true if block header must be written */ | |
1040 | ) | |
1041 | { | |
1042 | bi_windup(s); /* align on byte boundary */ | |
1043 | s->last_eob_len = 8; /* enough lookahead for inflate */ | |
1044 | ||
1045 | if (header) { | |
1046 | put_short(s, (ush)len); | |
1047 | put_short(s, (ush)~len); | |
1048 | #ifdef DEBUG_ZLIB | |
1049 | s->bits_sent += 2*16; | |
1050 | #endif | |
1051 | } | |
1052 | #ifdef DEBUG_ZLIB | |
1053 | s->bits_sent += (ulg)len<<3; | |
1054 | #endif | |
1055 | /* bundle up the put_byte(s, *buf++) calls */ | |
1056 | memcpy(&s->pending_buf[s->pending], buf, len); | |
1057 | s->pending += len; | |
1058 | } | |
1059 |