c62d2810 |
1 | /* trees.c -- output deflated data using Huffman coding |
2 | * Copyright (C) 1995-2002 Jean-loup Gailly |
3 | * For conditions of distribution and use, see copyright notice in zlib.h |
4 | */ |
5 | |
6 | /* |
7 | * ALGORITHM |
8 | * |
9 | * The "deflation" process uses several Huffman trees. The more |
10 | * common source values are represented by shorter bit sequences. |
11 | * |
12 | * Each code tree is stored in a compressed form which is itself |
13 | * a Huffman encoding of the lengths of all the code strings (in |
14 | * ascending order by source values). The actual code strings are |
15 | * reconstructed from the lengths in the inflate process, as described |
16 | * in the deflate specification. |
17 | * |
18 | * REFERENCES |
19 | * |
20 | * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification". |
21 | * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc |
22 | * |
23 | * Storer, James A. |
24 | * Data Compression: Methods and Theory, pp. 49-50. |
25 | * Computer Science Press, 1988. ISBN 0-7167-8156-5. |
26 | * |
27 | * Sedgewick, R. |
28 | * Algorithms, p290. |
29 | * Addison-Wesley, 1983. ISBN 0-201-06672-6. |
30 | */ |
31 | |
32 | /* @(#) $Id: trees.c,v 1.2 2002/03/13 17:45:56 xodnizel Exp $ */ |
33 | |
34 | /* #define GEN_TREES_H */ |
35 | |
36 | #include "deflate.h" |
37 | |
38 | #ifdef DEBUG |
39 | # include <ctype.h> |
40 | #endif |
41 | |
42 | /* =========================================================================== |
43 | * Constants |
44 | */ |
45 | |
46 | #define MAX_BL_BITS 7 |
47 | /* Bit length codes must not exceed MAX_BL_BITS bits */ |
48 | |
49 | #define END_BLOCK 256 |
50 | /* end of block literal code */ |
51 | |
52 | #define REP_3_6 16 |
53 | /* repeat previous bit length 3-6 times (2 bits of repeat count) */ |
54 | |
55 | #define REPZ_3_10 17 |
56 | /* repeat a zero length 3-10 times (3 bits of repeat count) */ |
57 | |
58 | #define REPZ_11_138 18 |
59 | /* repeat a zero length 11-138 times (7 bits of repeat count) */ |
60 | |
61 | local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ |
62 | = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0}; |
63 | |
64 | local const int extra_dbits[D_CODES] /* extra bits for each distance code */ |
65 | = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13}; |
66 | |
67 | local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */ |
68 | = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; |
69 | |
70 | local const uch bl_order[BL_CODES] |
71 | = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; |
72 | /* The lengths of the bit length codes are sent in order of decreasing |
73 | * probability, to avoid transmitting the lengths for unused bit length codes. |
74 | */ |
75 | |
76 | #define Buf_size (8 * 2*sizeof(char)) |
77 | /* Number of bits used within bi_buf. (bi_buf might be implemented on |
78 | * more than 16 bits on some systems.) |
79 | */ |
80 | |
81 | /* =========================================================================== |
82 | * Local data. These are initialized only once. |
83 | */ |
84 | |
85 | #define DIST_CODE_LEN 512 /* see definition of array dist_code below */ |
86 | |
87 | #if defined(GEN_TREES_H) || !defined(STDC) |
88 | /* non ANSI compilers may not accept trees.h */ |
89 | |
90 | local ct_data static_ltree[L_CODES+2]; |
91 | /* The static literal tree. Since the bit lengths are imposed, there is no |
92 | * need for the L_CODES extra codes used during heap construction. However |
93 | * The codes 286 and 287 are needed to build a canonical tree (see _tr_init |
94 | * below). |
95 | */ |
96 | |
97 | local ct_data static_dtree[D_CODES]; |
98 | /* The static distance tree. (Actually a trivial tree since all codes use |
99 | * 5 bits.) |
100 | */ |
101 | |
102 | uch _dist_code[DIST_CODE_LEN]; |
103 | /* Distance codes. The first 256 values correspond to the distances |
104 | * 3 .. 258, the last 256 values correspond to the top 8 bits of |
105 | * the 15 bit distances. |
106 | */ |
107 | |
108 | uch _length_code[MAX_MATCH-MIN_MATCH+1]; |
109 | /* length code for each normalized match length (0 == MIN_MATCH) */ |
110 | |
111 | local int base_length[LENGTH_CODES]; |
112 | /* First normalized length for each code (0 = MIN_MATCH) */ |
113 | |
114 | local int base_dist[D_CODES]; |
115 | /* First normalized distance for each code (0 = distance of 1) */ |
116 | |
117 | #else |
118 | # include "trees.h" |
119 | #endif /* GEN_TREES_H */ |
120 | |
121 | struct static_tree_desc_s { |
122 | const ct_data *static_tree; /* static tree or NULL */ |
123 | const intf *extra_bits; /* extra bits for each code or NULL */ |
124 | int extra_base; /* base index for extra_bits */ |
125 | int elems; /* max number of elements in the tree */ |
126 | int max_length; /* max bit length for the codes */ |
127 | }; |
128 | |
129 | local static_tree_desc static_l_desc = |
130 | {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; |
131 | |
132 | local static_tree_desc static_d_desc = |
133 | {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; |
134 | |
135 | local static_tree_desc static_bl_desc = |
136 | {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; |
137 | |
138 | /* =========================================================================== |
139 | * Local (static) routines in this file. |
140 | */ |
141 | |
142 | local void tr_static_init OF((void)); |
143 | local void init_block OF((deflate_state *s)); |
144 | local void pqdownheap OF((deflate_state *s, ct_data *tree, int k)); |
145 | local void gen_bitlen OF((deflate_state *s, tree_desc *desc)); |
146 | local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count)); |
147 | local void build_tree OF((deflate_state *s, tree_desc *desc)); |
148 | local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code)); |
149 | local void send_tree OF((deflate_state *s, ct_data *tree, int max_code)); |
150 | local int build_bl_tree OF((deflate_state *s)); |
151 | local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes, |
152 | int blcodes)); |
153 | local void compress_block OF((deflate_state *s, ct_data *ltree, |
154 | ct_data *dtree)); |
155 | local void set_data_type OF((deflate_state *s)); |
156 | local unsigned bi_reverse OF((unsigned value, int length)); |
157 | local void bi_windup OF((deflate_state *s)); |
158 | local void bi_flush OF((deflate_state *s)); |
159 | local void copy_block OF((deflate_state *s, charf *buf, unsigned len, |
160 | int header)); |
161 | |
162 | #ifdef GEN_TREES_H |
163 | local void gen_trees_header OF((void)); |
164 | #endif |
165 | |
166 | #ifndef DEBUG |
167 | # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len) |
168 | /* Send a code of the given tree. c and tree must not have side effects */ |
169 | |
170 | #else /* DEBUG */ |
171 | # define send_code(s, c, tree) \ |
172 | { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \ |
173 | send_bits(s, tree[c].Code, tree[c].Len); } |
174 | #endif |
175 | |
176 | /* =========================================================================== |
177 | * Output a short LSB first on the stream. |
178 | * IN assertion: there is enough room in pendingBuf. |
179 | */ |
180 | #define put_short(s, w) { \ |
181 | put_byte(s, (uch)((w) & 0xff)); \ |
182 | put_byte(s, (uch)((ush)(w) >> 8)); \ |
183 | } |
184 | |
185 | /* =========================================================================== |
186 | * Send a value on a given number of bits. |
187 | * IN assertion: length <= 16 and value fits in length bits. |
188 | */ |
189 | #ifdef DEBUG |
190 | local void send_bits OF((deflate_state *s, int value, int length)); |
191 | |
192 | local void send_bits(s, value, length) |
193 | deflate_state *s; |
194 | int value; /* value to send */ |
195 | int length; /* number of bits */ |
196 | { |
197 | Tracevv((stderr," l %2d v %4x ", length, value)); |
198 | Assert(length > 0 && length <= 15, "invalid length"); |
199 | s->bits_sent += (ulg)length; |
200 | |
201 | /* If not enough room in bi_buf, use (valid) bits from bi_buf and |
202 | * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid)) |
203 | * unused bits in value. |
204 | */ |
205 | if (s->bi_valid > (int)Buf_size - length) { |
206 | s->bi_buf |= (value << s->bi_valid); |
207 | put_short(s, s->bi_buf); |
208 | s->bi_buf = (ush)value >> (Buf_size - s->bi_valid); |
209 | s->bi_valid += length - Buf_size; |
210 | } else { |
211 | s->bi_buf |= value << s->bi_valid; |
212 | s->bi_valid += length; |
213 | } |
214 | } |
215 | #else /* !DEBUG */ |
216 | |
217 | #define send_bits(s, value, length) \ |
218 | { int len = length;\ |
219 | if (s->bi_valid > (int)Buf_size - len) {\ |
220 | int val = value;\ |
221 | s->bi_buf |= (val << s->bi_valid);\ |
222 | put_short(s, s->bi_buf);\ |
223 | s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\ |
224 | s->bi_valid += len - Buf_size;\ |
225 | } else {\ |
226 | s->bi_buf |= (value) << s->bi_valid;\ |
227 | s->bi_valid += len;\ |
228 | }\ |
229 | } |
230 | #endif /* DEBUG */ |
231 | |
232 | |
233 | #define MAX(a,b) (a >= b ? a : b) |
234 | /* the arguments must not have side effects */ |
235 | |
236 | /* =========================================================================== |
237 | * Initialize the various 'constant' tables. |
238 | */ |
239 | local void tr_static_init() |
240 | { |
241 | #if defined(GEN_TREES_H) || !defined(STDC) |
242 | static int static_init_done = 0; |
243 | int n; /* iterates over tree elements */ |
244 | int bits; /* bit counter */ |
245 | int length; /* length value */ |
246 | int code; /* code value */ |
247 | int dist; /* distance index */ |
248 | ush bl_count[MAX_BITS+1]; |
249 | /* number of codes at each bit length for an optimal tree */ |
250 | |
251 | if (static_init_done) return; |
252 | |
253 | /* For some embedded targets, global variables are not initialized: */ |
254 | static_l_desc.static_tree = static_ltree; |
255 | static_l_desc.extra_bits = extra_lbits; |
256 | static_d_desc.static_tree = static_dtree; |
257 | static_d_desc.extra_bits = extra_dbits; |
258 | static_bl_desc.extra_bits = extra_blbits; |
259 | |
260 | /* Initialize the mapping length (0..255) -> length code (0..28) */ |
261 | length = 0; |
262 | for (code = 0; code < LENGTH_CODES-1; code++) { |
263 | base_length[code] = length; |
264 | for (n = 0; n < (1<<extra_lbits[code]); n++) { |
265 | _length_code[length++] = (uch)code; |
266 | } |
267 | } |
268 | Assert (length == 256, "tr_static_init: length != 256"); |
269 | /* Note that the length 255 (match length 258) can be represented |
270 | * in two different ways: code 284 + 5 bits or code 285, so we |
271 | * overwrite length_code[255] to use the best encoding: |
272 | */ |
273 | _length_code[length-1] = (uch)code; |
274 | |
275 | /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ |
276 | dist = 0; |
277 | for (code = 0 ; code < 16; code++) { |
278 | base_dist[code] = dist; |
279 | for (n = 0; n < (1<<extra_dbits[code]); n++) { |
280 | _dist_code[dist++] = (uch)code; |
281 | } |
282 | } |
283 | Assert (dist == 256, "tr_static_init: dist != 256"); |
284 | dist >>= 7; /* from now on, all distances are divided by 128 */ |
285 | for ( ; code < D_CODES; code++) { |
286 | base_dist[code] = dist << 7; |
287 | for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { |
288 | _dist_code[256 + dist++] = (uch)code; |
289 | } |
290 | } |
291 | Assert (dist == 256, "tr_static_init: 256+dist != 512"); |
292 | |
293 | /* Construct the codes of the static literal tree */ |
294 | for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; |
295 | n = 0; |
296 | while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; |
297 | while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; |
298 | while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; |
299 | while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; |
300 | /* Codes 286 and 287 do not exist, but we must include them in the |
301 | * tree construction to get a canonical Huffman tree (longest code |
302 | * all ones) |
303 | */ |
304 | gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count); |
305 | |
306 | /* The static distance tree is trivial: */ |
307 | for (n = 0; n < D_CODES; n++) { |
308 | static_dtree[n].Len = 5; |
309 | static_dtree[n].Code = bi_reverse((unsigned)n, 5); |
310 | } |
311 | static_init_done = 1; |
312 | |
313 | # ifdef GEN_TREES_H |
314 | gen_trees_header(); |
315 | # endif |
316 | #endif /* defined(GEN_TREES_H) || !defined(STDC) */ |
317 | } |
318 | |
319 | /* =========================================================================== |
320 | * Genererate the file trees.h describing the static trees. |
321 | */ |
322 | #ifdef GEN_TREES_H |
323 | # ifndef DEBUG |
324 | # include <stdio.h> |
325 | # endif |
326 | |
327 | # define SEPARATOR(i, last, width) \ |
328 | ((i) == (last)? "\n};\n\n" : \ |
329 | ((i) % (width) == (width)-1 ? ",\n" : ", ")) |
330 | |
331 | void gen_trees_header() |
332 | { |
333 | FILE *header = fopen("trees.h", "w"); |
334 | int i; |
335 | |
336 | Assert (header != NULL, "Can't open trees.h"); |
337 | fprintf(header, |
338 | "/* header created automatically with -DGEN_TREES_H */\n\n"); |
339 | |
340 | fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n"); |
341 | for (i = 0; i < L_CODES+2; i++) { |
342 | fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code, |
343 | static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5)); |
344 | } |
345 | |
346 | fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n"); |
347 | for (i = 0; i < D_CODES; i++) { |
348 | fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code, |
349 | static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5)); |
350 | } |
351 | |
352 | fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n"); |
353 | for (i = 0; i < DIST_CODE_LEN; i++) { |
354 | fprintf(header, "%2u%s", _dist_code[i], |
355 | SEPARATOR(i, DIST_CODE_LEN-1, 20)); |
356 | } |
357 | |
358 | fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n"); |
359 | for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) { |
360 | fprintf(header, "%2u%s", _length_code[i], |
361 | SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20)); |
362 | } |
363 | |
364 | fprintf(header, "local const int base_length[LENGTH_CODES] = {\n"); |
365 | for (i = 0; i < LENGTH_CODES; i++) { |
366 | fprintf(header, "%1u%s", base_length[i], |
367 | SEPARATOR(i, LENGTH_CODES-1, 20)); |
368 | } |
369 | |
370 | fprintf(header, "local const int base_dist[D_CODES] = {\n"); |
371 | for (i = 0; i < D_CODES; i++) { |
372 | fprintf(header, "%5u%s", base_dist[i], |
373 | SEPARATOR(i, D_CODES-1, 10)); |
374 | } |
375 | |
376 | fclose(header); |
377 | } |
378 | #endif /* GEN_TREES_H */ |
379 | |
380 | /* =========================================================================== |
381 | * Initialize the tree data structures for a new zlib stream. |
382 | */ |
383 | void _tr_init(s) |
384 | deflate_state *s; |
385 | { |
386 | tr_static_init(); |
387 | |
388 | s->l_desc.dyn_tree = s->dyn_ltree; |
389 | s->l_desc.stat_desc = &static_l_desc; |
390 | |
391 | s->d_desc.dyn_tree = s->dyn_dtree; |
392 | s->d_desc.stat_desc = &static_d_desc; |
393 | |
394 | s->bl_desc.dyn_tree = s->bl_tree; |
395 | s->bl_desc.stat_desc = &static_bl_desc; |
396 | |
397 | s->bi_buf = 0; |
398 | s->bi_valid = 0; |
399 | s->last_eob_len = 8; /* enough lookahead for inflate */ |
400 | #ifdef DEBUG |
401 | s->compressed_len = 0L; |
402 | s->bits_sent = 0L; |
403 | #endif |
404 | |
405 | /* Initialize the first block of the first file: */ |
406 | init_block(s); |
407 | } |
408 | |
409 | /* =========================================================================== |
410 | * Initialize a new block. |
411 | */ |
412 | local void init_block(s) |
413 | deflate_state *s; |
414 | { |
415 | int n; /* iterates over tree elements */ |
416 | |
417 | /* Initialize the trees. */ |
418 | for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0; |
419 | for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0; |
420 | for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0; |
421 | |
422 | s->dyn_ltree[END_BLOCK].Freq = 1; |
423 | s->opt_len = s->static_len = 0L; |
424 | s->last_lit = s->matches = 0; |
425 | } |
426 | |
427 | #define SMALLEST 1 |
428 | /* Index within the heap array of least frequent node in the Huffman tree */ |
429 | |
430 | |
431 | /* =========================================================================== |
432 | * Remove the smallest element from the heap and recreate the heap with |
433 | * one less element. Updates heap and heap_len. |
434 | */ |
435 | #define pqremove(s, tree, top) \ |
436 | {\ |
437 | top = s->heap[SMALLEST]; \ |
438 | s->heap[SMALLEST] = s->heap[s->heap_len--]; \ |
439 | pqdownheap(s, tree, SMALLEST); \ |
440 | } |
441 | |
442 | /* =========================================================================== |
443 | * Compares to subtrees, using the tree depth as tie breaker when |
444 | * the subtrees have equal frequency. This minimizes the worst case length. |
445 | */ |
446 | #define smaller(tree, n, m, depth) \ |
447 | (tree[n].Freq < tree[m].Freq || \ |
448 | (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) |
449 | |
450 | /* =========================================================================== |
451 | * Restore the heap property by moving down the tree starting at node k, |
452 | * exchanging a node with the smallest of its two sons if necessary, stopping |
453 | * when the heap property is re-established (each father smaller than its |
454 | * two sons). |
455 | */ |
456 | local void pqdownheap(s, tree, k) |
457 | deflate_state *s; |
458 | ct_data *tree; /* the tree to restore */ |
459 | int k; /* node to move down */ |
460 | { |
461 | int v = s->heap[k]; |
462 | int j = k << 1; /* left son of k */ |
463 | while (j <= s->heap_len) { |
464 | /* Set j to the smallest of the two sons: */ |
465 | if (j < s->heap_len && |
466 | smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { |
467 | j++; |
468 | } |
469 | /* Exit if v is smaller than both sons */ |
470 | if (smaller(tree, v, s->heap[j], s->depth)) break; |
471 | |
472 | /* Exchange v with the smallest son */ |
473 | s->heap[k] = s->heap[j]; k = j; |
474 | |
475 | /* And continue down the tree, setting j to the left son of k */ |
476 | j <<= 1; |
477 | } |
478 | s->heap[k] = v; |
479 | } |
480 | |
481 | /* =========================================================================== |
482 | * Compute the optimal bit lengths for a tree and update the total bit length |
483 | * for the current block. |
484 | * IN assertion: the fields freq and dad are set, heap[heap_max] and |
485 | * above are the tree nodes sorted by increasing frequency. |
486 | * OUT assertions: the field len is set to the optimal bit length, the |
487 | * array bl_count contains the frequencies for each bit length. |
488 | * The length opt_len is updated; static_len is also updated if stree is |
489 | * not null. |
490 | */ |
491 | local void gen_bitlen(s, desc) |
492 | deflate_state *s; |
493 | tree_desc *desc; /* the tree descriptor */ |
494 | { |
495 | ct_data *tree = desc->dyn_tree; |
496 | int max_code = desc->max_code; |
497 | const ct_data *stree = desc->stat_desc->static_tree; |
498 | const intf *extra = desc->stat_desc->extra_bits; |
499 | int base = desc->stat_desc->extra_base; |
500 | int max_length = desc->stat_desc->max_length; |
501 | int h; /* heap index */ |
502 | int n, m; /* iterate over the tree elements */ |
503 | int bits; /* bit length */ |
504 | int xbits; /* extra bits */ |
505 | ush f; /* frequency */ |
506 | int overflow = 0; /* number of elements with bit length too large */ |
507 | |
508 | for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0; |
509 | |
510 | /* In a first pass, compute the optimal bit lengths (which may |
511 | * overflow in the case of the bit length tree). |
512 | */ |
513 | tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ |
514 | |
515 | for (h = s->heap_max+1; h < HEAP_SIZE; h++) { |
516 | n = s->heap[h]; |
517 | bits = tree[tree[n].Dad].Len + 1; |
518 | if (bits > max_length) bits = max_length, overflow++; |
519 | tree[n].Len = (ush)bits; |
520 | /* We overwrite tree[n].Dad which is no longer needed */ |
521 | |
522 | if (n > max_code) continue; /* not a leaf node */ |
523 | |
524 | s->bl_count[bits]++; |
525 | xbits = 0; |
526 | if (n >= base) xbits = extra[n-base]; |
527 | f = tree[n].Freq; |
528 | s->opt_len += (ulg)f * (bits + xbits); |
529 | if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits); |
530 | } |
531 | if (overflow == 0) return; |
532 | |
533 | Trace((stderr,"\nbit length overflow\n")); |
534 | /* This happens for example on obj2 and pic of the Calgary corpus */ |
535 | |
536 | /* Find the first bit length which could increase: */ |
537 | do { |
538 | bits = max_length-1; |
539 | while (s->bl_count[bits] == 0) bits--; |
540 | s->bl_count[bits]--; /* move one leaf down the tree */ |
541 | s->bl_count[bits+1] += 2; /* move one overflow item as its brother */ |
542 | s->bl_count[max_length]--; |
543 | /* The brother of the overflow item also moves one step up, |
544 | * but this does not affect bl_count[max_length] |
545 | */ |
546 | overflow -= 2; |
547 | } while (overflow > 0); |
548 | |
549 | /* Now recompute all bit lengths, scanning in increasing frequency. |
550 | * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all |
551 | * lengths instead of fixing only the wrong ones. This idea is taken |
552 | * from 'ar' written by Haruhiko Okumura.) |
553 | */ |
554 | for (bits = max_length; bits != 0; bits--) { |
555 | n = s->bl_count[bits]; |
556 | while (n != 0) { |
557 | m = s->heap[--h]; |
558 | if (m > max_code) continue; |
559 | if (tree[m].Len != (unsigned) bits) { |
560 | Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); |
561 | s->opt_len += ((long)bits - (long)tree[m].Len) |
562 | *(long)tree[m].Freq; |
563 | tree[m].Len = (ush)bits; |
564 | } |
565 | n--; |
566 | } |
567 | } |
568 | } |
569 | |
570 | /* =========================================================================== |
571 | * Generate the codes for a given tree and bit counts (which need not be |
572 | * optimal). |
573 | * IN assertion: the array bl_count contains the bit length statistics for |
574 | * the given tree and the field len is set for all tree elements. |
575 | * OUT assertion: the field code is set for all tree elements of non |
576 | * zero code length. |
577 | */ |
578 | local void gen_codes (tree, max_code, bl_count) |
579 | ct_data *tree; /* the tree to decorate */ |
580 | int max_code; /* largest code with non zero frequency */ |
581 | ushf *bl_count; /* number of codes at each bit length */ |
582 | { |
583 | ush next_code[MAX_BITS+1]; /* next code value for each bit length */ |
584 | ush code = 0; /* running code value */ |
585 | int bits; /* bit index */ |
586 | int n; /* code index */ |
587 | |
588 | /* The distribution counts are first used to generate the code values |
589 | * without bit reversal. |
590 | */ |
591 | for (bits = 1; bits <= MAX_BITS; bits++) { |
592 | next_code[bits] = code = (code + bl_count[bits-1]) << 1; |
593 | } |
594 | /* Check that the bit counts in bl_count are consistent. The last code |
595 | * must be all ones. |
596 | */ |
597 | Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, |
598 | "inconsistent bit counts"); |
599 | Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); |
600 | |
601 | for (n = 0; n <= max_code; n++) { |
602 | int len = tree[n].Len; |
603 | if (len == 0) continue; |
604 | /* Now reverse the bits */ |
605 | tree[n].Code = bi_reverse(next_code[len]++, len); |
606 | |
607 | Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", |
608 | n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); |
609 | } |
610 | } |
611 | |
612 | /* =========================================================================== |
613 | * Construct one Huffman tree and assigns the code bit strings and lengths. |
614 | * Update the total bit length for the current block. |
615 | * IN assertion: the field freq is set for all tree elements. |
616 | * OUT assertions: the fields len and code are set to the optimal bit length |
617 | * and corresponding code. The length opt_len is updated; static_len is |
618 | * also updated if stree is not null. The field max_code is set. |
619 | */ |
620 | local void build_tree(s, desc) |
621 | deflate_state *s; |
622 | tree_desc *desc; /* the tree descriptor */ |
623 | { |
624 | ct_data *tree = desc->dyn_tree; |
625 | const ct_data *stree = desc->stat_desc->static_tree; |
626 | int elems = desc->stat_desc->elems; |
627 | int n, m; /* iterate over heap elements */ |
628 | int max_code = -1; /* largest code with non zero frequency */ |
629 | int node; /* new node being created */ |
630 | |
631 | /* Construct the initial heap, with least frequent element in |
632 | * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. |
633 | * heap[0] is not used. |
634 | */ |
635 | s->heap_len = 0, s->heap_max = HEAP_SIZE; |
636 | |
637 | for (n = 0; n < elems; n++) { |
638 | if (tree[n].Freq != 0) { |
639 | s->heap[++(s->heap_len)] = max_code = n; |
640 | s->depth[n] = 0; |
641 | } else { |
642 | tree[n].Len = 0; |
643 | } |
644 | } |
645 | |
646 | /* The pkzip format requires that at least one distance code exists, |
647 | * and that at least one bit should be sent even if there is only one |
648 | * possible code. So to avoid special checks later on we force at least |
649 | * two codes of non zero frequency. |
650 | */ |
651 | while (s->heap_len < 2) { |
652 | node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0); |
653 | tree[node].Freq = 1; |
654 | s->depth[node] = 0; |
655 | s->opt_len--; if (stree) s->static_len -= stree[node].Len; |
656 | /* node is 0 or 1 so it does not have extra bits */ |
657 | } |
658 | desc->max_code = max_code; |
659 | |
660 | /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, |
661 | * establish sub-heaps of increasing lengths: |
662 | */ |
663 | for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n); |
664 | |
665 | /* Construct the Huffman tree by repeatedly combining the least two |
666 | * frequent nodes. |
667 | */ |
668 | node = elems; /* next internal node of the tree */ |
669 | do { |
670 | pqremove(s, tree, n); /* n = node of least frequency */ |
671 | m = s->heap[SMALLEST]; /* m = node of next least frequency */ |
672 | |
673 | s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */ |
674 | s->heap[--(s->heap_max)] = m; |
675 | |
676 | /* Create a new node father of n and m */ |
677 | tree[node].Freq = tree[n].Freq + tree[m].Freq; |
678 | s->depth[node] = (uch) (MAX(s->depth[n], s->depth[m]) + 1); |
679 | tree[n].Dad = tree[m].Dad = (ush)node; |
680 | #ifdef DUMP_BL_TREE |
681 | if (tree == s->bl_tree) { |
682 | fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", |
683 | node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); |
684 | } |
685 | #endif |
686 | /* and insert the new node in the heap */ |
687 | s->heap[SMALLEST] = node++; |
688 | pqdownheap(s, tree, SMALLEST); |
689 | |
690 | } while (s->heap_len >= 2); |
691 | |
692 | s->heap[--(s->heap_max)] = s->heap[SMALLEST]; |
693 | |
694 | /* At this point, the fields freq and dad are set. We can now |
695 | * generate the bit lengths. |
696 | */ |
697 | gen_bitlen(s, (tree_desc *)desc); |
698 | |
699 | /* The field len is now set, we can generate the bit codes */ |
700 | gen_codes ((ct_data *)tree, max_code, s->bl_count); |
701 | } |
702 | |
703 | /* =========================================================================== |
704 | * Scan a literal or distance tree to determine the frequencies of the codes |
705 | * in the bit length tree. |
706 | */ |
707 | local void scan_tree (s, tree, max_code) |
708 | deflate_state *s; |
709 | ct_data *tree; /* the tree to be scanned */ |
710 | int max_code; /* and its largest code of non zero frequency */ |
711 | { |
712 | int n; /* iterates over all tree elements */ |
713 | int prevlen = -1; /* last emitted length */ |
714 | int curlen; /* length of current code */ |
715 | int nextlen = tree[0].Len; /* length of next code */ |
716 | int count = 0; /* repeat count of the current code */ |
717 | int max_count = 7; /* max repeat count */ |
718 | int min_count = 4; /* min repeat count */ |
719 | |
720 | if (nextlen == 0) max_count = 138, min_count = 3; |
721 | tree[max_code+1].Len = (ush)0xffff; /* guard */ |
722 | |
723 | for (n = 0; n <= max_code; n++) { |
724 | curlen = nextlen; nextlen = tree[n+1].Len; |
725 | if (++count < max_count && curlen == nextlen) { |
726 | continue; |
727 | } else if (count < min_count) { |
728 | s->bl_tree[curlen].Freq += count; |
729 | } else if (curlen != 0) { |
730 | if (curlen != prevlen) s->bl_tree[curlen].Freq++; |
731 | s->bl_tree[REP_3_6].Freq++; |
732 | } else if (count <= 10) { |
733 | s->bl_tree[REPZ_3_10].Freq++; |
734 | } else { |
735 | s->bl_tree[REPZ_11_138].Freq++; |
736 | } |
737 | count = 0; prevlen = curlen; |
738 | if (nextlen == 0) { |
739 | max_count = 138, min_count = 3; |
740 | } else if (curlen == nextlen) { |
741 | max_count = 6, min_count = 3; |
742 | } else { |
743 | max_count = 7, min_count = 4; |
744 | } |
745 | } |
746 | } |
747 | |
748 | /* =========================================================================== |
749 | * Send a literal or distance tree in compressed form, using the codes in |
750 | * bl_tree. |
751 | */ |
752 | local void send_tree (s, tree, max_code) |
753 | deflate_state *s; |
754 | ct_data *tree; /* the tree to be scanned */ |
755 | int max_code; /* and its largest code of non zero frequency */ |
756 | { |
757 | int n; /* iterates over all tree elements */ |
758 | int prevlen = -1; /* last emitted length */ |
759 | int curlen; /* length of current code */ |
760 | int nextlen = tree[0].Len; /* length of next code */ |
761 | int count = 0; /* repeat count of the current code */ |
762 | int max_count = 7; /* max repeat count */ |
763 | int min_count = 4; /* min repeat count */ |
764 | |
765 | /* tree[max_code+1].Len = -1; */ /* guard already set */ |
766 | if (nextlen == 0) max_count = 138, min_count = 3; |
767 | |
768 | for (n = 0; n <= max_code; n++) { |
769 | curlen = nextlen; nextlen = tree[n+1].Len; |
770 | if (++count < max_count && curlen == nextlen) { |
771 | continue; |
772 | } else if (count < min_count) { |
773 | do { send_code(s, curlen, s->bl_tree); } while (--count != 0); |
774 | |
775 | } else if (curlen != 0) { |
776 | if (curlen != prevlen) { |
777 | send_code(s, curlen, s->bl_tree); count--; |
778 | } |
779 | Assert(count >= 3 && count <= 6, " 3_6?"); |
780 | send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2); |
781 | |
782 | } else if (count <= 10) { |
783 | send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3); |
784 | |
785 | } else { |
786 | send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7); |
787 | } |
788 | count = 0; prevlen = curlen; |
789 | if (nextlen == 0) { |
790 | max_count = 138, min_count = 3; |
791 | } else if (curlen == nextlen) { |
792 | max_count = 6, min_count = 3; |
793 | } else { |
794 | max_count = 7, min_count = 4; |
795 | } |
796 | } |
797 | } |
798 | |
799 | /* =========================================================================== |
800 | * Construct the Huffman tree for the bit lengths and return the index in |
801 | * bl_order of the last bit length code to send. |
802 | */ |
803 | local int build_bl_tree(s) |
804 | deflate_state *s; |
805 | { |
806 | int max_blindex; /* index of last bit length code of non zero freq */ |
807 | |
808 | /* Determine the bit length frequencies for literal and distance trees */ |
809 | scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code); |
810 | scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code); |
811 | |
812 | /* Build the bit length tree: */ |
813 | build_tree(s, (tree_desc *)(&(s->bl_desc))); |
814 | /* opt_len now includes the length of the tree representations, except |
815 | * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. |
816 | */ |
817 | |
818 | /* Determine the number of bit length codes to send. The pkzip format |
819 | * requires that at least 4 bit length codes be sent. (appnote.txt says |
820 | * 3 but the actual value used is 4.) |
821 | */ |
822 | for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { |
823 | if (s->bl_tree[bl_order[max_blindex]].Len != 0) break; |
824 | } |
825 | /* Update opt_len to include the bit length tree and counts */ |
826 | s->opt_len += 3*(max_blindex+1) + 5+5+4; |
827 | Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", |
828 | s->opt_len, s->static_len)); |
829 | |
830 | return max_blindex; |
831 | } |
832 | |
833 | /* =========================================================================== |
834 | * Send the header for a block using dynamic Huffman trees: the counts, the |
835 | * lengths of the bit length codes, the literal tree and the distance tree. |
836 | * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. |
837 | */ |
838 | local void send_all_trees(s, lcodes, dcodes, blcodes) |
839 | deflate_state *s; |
840 | int lcodes, dcodes, blcodes; /* number of codes for each tree */ |
841 | { |
842 | int rank; /* index in bl_order */ |
843 | |
844 | Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); |
845 | Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, |
846 | "too many codes"); |
847 | Tracev((stderr, "\nbl counts: ")); |
848 | send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */ |
849 | send_bits(s, dcodes-1, 5); |
850 | send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */ |
851 | for (rank = 0; rank < blcodes; rank++) { |
852 | Tracev((stderr, "\nbl code %2d ", bl_order[rank])); |
853 | send_bits(s, s->bl_tree[bl_order[rank]].Len, 3); |
854 | } |
855 | Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent)); |
856 | |
857 | send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */ |
858 | Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent)); |
859 | |
860 | send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */ |
861 | Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent)); |
862 | } |
863 | |
864 | /* =========================================================================== |
865 | * Send a stored block |
866 | */ |
867 | void _tr_stored_block(s, buf, stored_len, eof) |
868 | deflate_state *s; |
869 | charf *buf; /* input block */ |
870 | ulg stored_len; /* length of input block */ |
871 | int eof; /* true if this is the last block for a file */ |
872 | { |
873 | send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */ |
874 | #ifdef DEBUG |
875 | s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L; |
876 | s->compressed_len += (stored_len + 4) << 3; |
877 | #endif |
878 | copy_block(s, buf, (unsigned)stored_len, 1); /* with header */ |
879 | } |
880 | |
881 | /* =========================================================================== |
882 | * Send one empty static block to give enough lookahead for inflate. |
883 | * This takes 10 bits, of which 7 may remain in the bit buffer. |
884 | * The current inflate code requires 9 bits of lookahead. If the |
885 | * last two codes for the previous block (real code plus EOB) were coded |
886 | * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode |
887 | * the last real code. In this case we send two empty static blocks instead |
888 | * of one. (There are no problems if the previous block is stored or fixed.) |
889 | * To simplify the code, we assume the worst case of last real code encoded |
890 | * on one bit only. |
891 | */ |
892 | void _tr_align(s) |
893 | deflate_state *s; |
894 | { |
895 | send_bits(s, STATIC_TREES<<1, 3); |
896 | send_code(s, END_BLOCK, static_ltree); |
897 | #ifdef DEBUG |
898 | s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ |
899 | #endif |
900 | bi_flush(s); |
901 | /* Of the 10 bits for the empty block, we have already sent |
902 | * (10 - bi_valid) bits. The lookahead for the last real code (before |
903 | * the EOB of the previous block) was thus at least one plus the length |
904 | * of the EOB plus what we have just sent of the empty static block. |
905 | */ |
906 | if (1 + s->last_eob_len + 10 - s->bi_valid < 9) { |
907 | send_bits(s, STATIC_TREES<<1, 3); |
908 | send_code(s, END_BLOCK, static_ltree); |
909 | #ifdef DEBUG |
910 | s->compressed_len += 10L; |
911 | #endif |
912 | bi_flush(s); |
913 | } |
914 | s->last_eob_len = 7; |
915 | } |
916 | |
917 | /* =========================================================================== |
918 | * Determine the best encoding for the current block: dynamic trees, static |
919 | * trees or store, and output the encoded block to the zip file. |
920 | */ |
921 | void _tr_flush_block(s, buf, stored_len, eof) |
922 | deflate_state *s; |
923 | charf *buf; /* input block, or NULL if too old */ |
924 | ulg stored_len; /* length of input block */ |
925 | int eof; /* true if this is the last block for a file */ |
926 | { |
927 | ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ |
928 | int max_blindex = 0; /* index of last bit length code of non zero freq */ |
929 | |
930 | /* Build the Huffman trees unless a stored block is forced */ |
931 | if (s->level > 0) { |
932 | |
933 | /* Check if the file is ascii or binary */ |
934 | if (s->data_type == Z_UNKNOWN) set_data_type(s); |
935 | |
936 | /* Construct the literal and distance trees */ |
937 | build_tree(s, (tree_desc *)(&(s->l_desc))); |
938 | Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len, |
939 | s->static_len)); |
940 | |
941 | build_tree(s, (tree_desc *)(&(s->d_desc))); |
942 | Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len, |
943 | s->static_len)); |
944 | /* At this point, opt_len and static_len are the total bit lengths of |
945 | * the compressed block data, excluding the tree representations. |
946 | */ |
947 | |
948 | /* Build the bit length tree for the above two trees, and get the index |
949 | * in bl_order of the last bit length code to send. |
950 | */ |
951 | max_blindex = build_bl_tree(s); |
952 | |
953 | /* Determine the best encoding. Compute first the block length in bytes*/ |
954 | opt_lenb = (s->opt_len+3+7)>>3; |
955 | static_lenb = (s->static_len+3+7)>>3; |
956 | |
957 | Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ", |
958 | opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, |
959 | s->last_lit)); |
960 | |
961 | if (static_lenb <= opt_lenb) opt_lenb = static_lenb; |
962 | |
963 | } else { |
964 | Assert(buf != (char*)0, "lost buf"); |
965 | opt_lenb = static_lenb = stored_len + 5; /* force a stored block */ |
966 | } |
967 | |
968 | #ifdef FORCE_STORED |
969 | if (buf != (char*)0) { /* force stored block */ |
970 | #else |
971 | if (stored_len+4 <= opt_lenb && buf != (char*)0) { |
972 | /* 4: two words for the lengths */ |
973 | #endif |
974 | /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. |
975 | * Otherwise we can't have processed more than WSIZE input bytes since |
976 | * the last block flush, because compression would have been |
977 | * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to |
978 | * transform a block into a stored block. |
979 | */ |
980 | _tr_stored_block(s, buf, stored_len, eof); |
981 | |
982 | #ifdef FORCE_STATIC |
983 | } else if (static_lenb >= 0) { /* force static trees */ |
984 | #else |
985 | } else if (static_lenb == opt_lenb) { |
986 | #endif |
987 | send_bits(s, (STATIC_TREES<<1)+eof, 3); |
988 | compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree); |
989 | #ifdef DEBUG |
990 | s->compressed_len += 3 + s->static_len; |
991 | #endif |
992 | } else { |
993 | send_bits(s, (DYN_TREES<<1)+eof, 3); |
994 | send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1, |
995 | max_blindex+1); |
996 | compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree); |
997 | #ifdef DEBUG |
998 | s->compressed_len += 3 + s->opt_len; |
999 | #endif |
1000 | } |
1001 | Assert (s->compressed_len == s->bits_sent, "bad compressed size"); |
1002 | /* The above check is made mod 2^32, for files larger than 512 MB |
1003 | * and uLong implemented on 32 bits. |
1004 | */ |
1005 | init_block(s); |
1006 | |
1007 | if (eof) { |
1008 | bi_windup(s); |
1009 | #ifdef DEBUG |
1010 | s->compressed_len += 7; /* align on byte boundary */ |
1011 | #endif |
1012 | } |
1013 | Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3, |
1014 | s->compressed_len-7*eof)); |
1015 | } |
1016 | |
1017 | /* =========================================================================== |
1018 | * Save the match info and tally the frequency counts. Return true if |
1019 | * the current block must be flushed. |
1020 | */ |
1021 | int _tr_tally (s, dist, lc) |
1022 | deflate_state *s; |
1023 | unsigned dist; /* distance of matched string */ |
1024 | unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ |
1025 | { |
1026 | s->d_buf[s->last_lit] = (ush)dist; |
1027 | s->l_buf[s->last_lit++] = (uch)lc; |
1028 | if (dist == 0) { |
1029 | /* lc is the unmatched char */ |
1030 | s->dyn_ltree[lc].Freq++; |
1031 | } else { |
1032 | s->matches++; |
1033 | /* Here, lc is the match length - MIN_MATCH */ |
1034 | dist--; /* dist = match distance - 1 */ |
1035 | Assert((ush)dist < (ush)MAX_DIST(s) && |
1036 | (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && |
1037 | (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match"); |
1038 | |
1039 | s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++; |
1040 | s->dyn_dtree[d_code(dist)].Freq++; |
1041 | } |
1042 | |
1043 | #ifdef TRUNCATE_BLOCK |
1044 | /* Try to guess if it is profitable to stop the current block here */ |
1045 | if ((s->last_lit & 0x1fff) == 0 && s->level > 2) { |
1046 | /* Compute an upper bound for the compressed length */ |
1047 | ulg out_length = (ulg)s->last_lit*8L; |
1048 | ulg in_length = (ulg)((long)s->strstart - s->block_start); |
1049 | int dcode; |
1050 | for (dcode = 0; dcode < D_CODES; dcode++) { |
1051 | out_length += (ulg)s->dyn_dtree[dcode].Freq * |
1052 | (5L+extra_dbits[dcode]); |
1053 | } |
1054 | out_length >>= 3; |
1055 | Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ", |
1056 | s->last_lit, in_length, out_length, |
1057 | 100L - out_length*100L/in_length)); |
1058 | if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1; |
1059 | } |
1060 | #endif |
1061 | return (s->last_lit == s->lit_bufsize-1); |
1062 | /* We avoid equality with lit_bufsize because of wraparound at 64K |
1063 | * on 16 bit machines and because stored blocks are restricted to |
1064 | * 64K-1 bytes. |
1065 | */ |
1066 | } |
1067 | |
1068 | /* =========================================================================== |
1069 | * Send the block data compressed using the given Huffman trees |
1070 | */ |
1071 | local void compress_block(s, ltree, dtree) |
1072 | deflate_state *s; |
1073 | ct_data *ltree; /* literal tree */ |
1074 | ct_data *dtree; /* distance tree */ |
1075 | { |
1076 | unsigned dist; /* distance of matched string */ |
1077 | int lc; /* match length or unmatched char (if dist == 0) */ |
1078 | unsigned lx = 0; /* running index in l_buf */ |
1079 | unsigned code; /* the code to send */ |
1080 | int extra; /* number of extra bits to send */ |
1081 | |
1082 | if (s->last_lit != 0) do { |
1083 | dist = s->d_buf[lx]; |
1084 | lc = s->l_buf[lx++]; |
1085 | if (dist == 0) { |
1086 | send_code(s, lc, ltree); /* send a literal byte */ |
1087 | Tracecv(isgraph(lc), (stderr," '%c' ", lc)); |
1088 | } else { |
1089 | /* Here, lc is the match length - MIN_MATCH */ |
1090 | code = _length_code[lc]; |
1091 | send_code(s, code+LITERALS+1, ltree); /* send the length code */ |
1092 | extra = extra_lbits[code]; |
1093 | if (extra != 0) { |
1094 | lc -= base_length[code]; |
1095 | send_bits(s, lc, extra); /* send the extra length bits */ |
1096 | } |
1097 | dist--; /* dist is now the match distance - 1 */ |
1098 | code = d_code(dist); |
1099 | Assert (code < D_CODES, "bad d_code"); |
1100 | |
1101 | send_code(s, code, dtree); /* send the distance code */ |
1102 | extra = extra_dbits[code]; |
1103 | if (extra != 0) { |
1104 | dist -= base_dist[code]; |
1105 | send_bits(s, dist, extra); /* send the extra distance bits */ |
1106 | } |
1107 | } /* literal or match pair ? */ |
1108 | |
1109 | /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */ |
1110 | Assert(s->pending < s->lit_bufsize + 2*lx, "pendingBuf overflow"); |
1111 | |
1112 | } while (lx < s->last_lit); |
1113 | |
1114 | send_code(s, END_BLOCK, ltree); |
1115 | s->last_eob_len = ltree[END_BLOCK].Len; |
1116 | } |
1117 | |
1118 | /* =========================================================================== |
1119 | * Set the data type to ASCII or BINARY, using a crude approximation: |
1120 | * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise. |
1121 | * IN assertion: the fields freq of dyn_ltree are set and the total of all |
1122 | * frequencies does not exceed 64K (to fit in an int on 16 bit machines). |
1123 | */ |
1124 | local void set_data_type(s) |
1125 | deflate_state *s; |
1126 | { |
1127 | int n = 0; |
1128 | unsigned ascii_freq = 0; |
1129 | unsigned bin_freq = 0; |
1130 | while (n < 7) bin_freq += s->dyn_ltree[n++].Freq; |
1131 | while (n < 128) ascii_freq += s->dyn_ltree[n++].Freq; |
1132 | while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq; |
1133 | s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? Z_BINARY : Z_ASCII); |
1134 | } |
1135 | |
1136 | /* =========================================================================== |
1137 | * Reverse the first len bits of a code, using straightforward code (a faster |
1138 | * method would use a table) |
1139 | * IN assertion: 1 <= len <= 15 |
1140 | */ |
1141 | local unsigned bi_reverse(code, len) |
1142 | unsigned code; /* the value to invert */ |
1143 | int len; /* its bit length */ |
1144 | { |
1145 | register unsigned res = 0; |
1146 | do { |
1147 | res |= code & 1; |
1148 | code >>= 1, res <<= 1; |
1149 | } while (--len > 0); |
1150 | return res >> 1; |
1151 | } |
1152 | |
1153 | /* =========================================================================== |
1154 | * Flush the bit buffer, keeping at most 7 bits in it. |
1155 | */ |
1156 | local void bi_flush(s) |
1157 | deflate_state *s; |
1158 | { |
1159 | if (s->bi_valid == 16) { |
1160 | put_short(s, s->bi_buf); |
1161 | s->bi_buf = 0; |
1162 | s->bi_valid = 0; |
1163 | } else if (s->bi_valid >= 8) { |
1164 | put_byte(s, (Byte)s->bi_buf); |
1165 | s->bi_buf >>= 8; |
1166 | s->bi_valid -= 8; |
1167 | } |
1168 | } |
1169 | |
1170 | /* =========================================================================== |
1171 | * Flush the bit buffer and align the output on a byte boundary |
1172 | */ |
1173 | local void bi_windup(s) |
1174 | deflate_state *s; |
1175 | { |
1176 | if (s->bi_valid > 8) { |
1177 | put_short(s, s->bi_buf); |
1178 | } else if (s->bi_valid > 0) { |
1179 | put_byte(s, (Byte)s->bi_buf); |
1180 | } |
1181 | s->bi_buf = 0; |
1182 | s->bi_valid = 0; |
1183 | #ifdef DEBUG |
1184 | s->bits_sent = (s->bits_sent+7) & ~7; |
1185 | #endif |
1186 | } |
1187 | |
1188 | /* =========================================================================== |
1189 | * Copy a stored block, storing first the length and its |
1190 | * one's complement if requested. |
1191 | */ |
1192 | local void copy_block(s, buf, len, header) |
1193 | deflate_state *s; |
1194 | charf *buf; /* the input data */ |
1195 | unsigned len; /* its length */ |
1196 | int header; /* true if block header must be written */ |
1197 | { |
1198 | bi_windup(s); /* align on byte boundary */ |
1199 | s->last_eob_len = 8; /* enough lookahead for inflate */ |
1200 | |
1201 | if (header) { |
1202 | put_short(s, (ush)len); |
1203 | put_short(s, (ush)~len); |
1204 | #ifdef DEBUG |
1205 | s->bits_sent += 2*16; |
1206 | #endif |
1207 | } |
1208 | #ifdef DEBUG |
1209 | s->bits_sent += (ulg)len<<3; |
1210 | #endif |
1211 | while (len--) { |
1212 | put_byte(s, *buf++); |
1213 | } |
1214 | } |