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Fri Apr 24 18:32:46 2009 UTC (15 years ago) by niro
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Fri Apr 24 18:32:46 2009 UTC (15 years ago) by niro
File MIME type: text/plain
File size: 40390 byte(s)
-updated to klibc-1.5.15
1 | niro | 532 | /* trees.c -- output deflated data using Huffman coding |
2 | * Copyright (C) 1992-1993 Jean-loup Gailly | ||
3 | * This is free software; you can redistribute it and/or modify it under the | ||
4 | * terms of the GNU General Public License, see the file COPYING. | ||
5 | */ | ||
6 | |||
7 | /* | ||
8 | * PURPOSE | ||
9 | * | ||
10 | * Encode various sets of source values using variable-length | ||
11 | * binary code trees. | ||
12 | * | ||
13 | * DISCUSSION | ||
14 | * | ||
15 | * The PKZIP "deflation" process uses several Huffman trees. The more | ||
16 | * common source values are represented by shorter bit sequences. | ||
17 | * | ||
18 | * Each code tree is stored in the ZIP file in a compressed form | ||
19 | * which is itself a Huffman encoding of the lengths of | ||
20 | * all the code strings (in ascending order by source values). | ||
21 | * The actual code strings are reconstructed from the lengths in | ||
22 | * the UNZIP process, as described in the "application note" | ||
23 | * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program. | ||
24 | * | ||
25 | * REFERENCES | ||
26 | * | ||
27 | * Lynch, Thomas J. | ||
28 | * Data Compression: Techniques and Applications, pp. 53-55. | ||
29 | * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7. | ||
30 | * | ||
31 | * Storer, James A. | ||
32 | * Data Compression: Methods and Theory, pp. 49-50. | ||
33 | * Computer Science Press, 1988. ISBN 0-7167-8156-5. | ||
34 | * | ||
35 | * Sedgewick, R. | ||
36 | * Algorithms, p290. | ||
37 | * Addison-Wesley, 1983. ISBN 0-201-06672-6. | ||
38 | * | ||
39 | * INTERFACE | ||
40 | * | ||
41 | * void ct_init (ush *attr, int *methodp) | ||
42 | * Allocate the match buffer, initialize the various tables and save | ||
43 | * the location of the internal file attribute (ascii/binary) and | ||
44 | * method (DEFLATE/STORE) | ||
45 | * | ||
46 | * void ct_tally (int dist, int lc); | ||
47 | * Save the match info and tally the frequency counts. | ||
48 | * | ||
49 | * long flush_block (char *buf, ulg stored_len, int eof) | ||
50 | * Determine the best encoding for the current block: dynamic trees, | ||
51 | * static trees or store, and output the encoded block to the zip | ||
52 | * file. Returns the total compressed length for the file so far. | ||
53 | * | ||
54 | */ | ||
55 | |||
56 | #include <ctype.h> | ||
57 | |||
58 | #include "tailor.h" | ||
59 | #include "gzip.h" | ||
60 | |||
61 | #ifdef RCSID | ||
62 | niro | 815 | static char rcsid[] = "$Id: trees.c,v 1.1 2002/08/18 00:59:21 hpa Exp $"; |
63 | niro | 532 | #endif |
64 | |||
65 | /* =========================================================================== | ||
66 | * Constants | ||
67 | */ | ||
68 | |||
69 | #define MAX_BITS 15 | ||
70 | /* All codes must not exceed MAX_BITS bits */ | ||
71 | |||
72 | #define MAX_BL_BITS 7 | ||
73 | /* Bit length codes must not exceed MAX_BL_BITS bits */ | ||
74 | |||
75 | #define LENGTH_CODES 29 | ||
76 | /* number of length codes, not counting the special END_BLOCK code */ | ||
77 | |||
78 | #define LITERALS 256 | ||
79 | /* number of literal bytes 0..255 */ | ||
80 | |||
81 | #define END_BLOCK 256 | ||
82 | /* end of block literal code */ | ||
83 | |||
84 | #define L_CODES (LITERALS+1+LENGTH_CODES) | ||
85 | /* number of Literal or Length codes, including the END_BLOCK code */ | ||
86 | |||
87 | #define D_CODES 30 | ||
88 | /* number of distance codes */ | ||
89 | |||
90 | #define BL_CODES 19 | ||
91 | /* number of codes used to transfer the bit lengths */ | ||
92 | |||
93 | |||
94 | local int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ | ||
95 | = {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}; | ||
96 | |||
97 | local int extra_dbits[D_CODES] /* extra bits for each distance code */ | ||
98 | = {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}; | ||
99 | |||
100 | local int extra_blbits[BL_CODES]/* extra bits for each bit length code */ | ||
101 | = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; | ||
102 | |||
103 | #define STORED_BLOCK 0 | ||
104 | #define STATIC_TREES 1 | ||
105 | #define DYN_TREES 2 | ||
106 | /* The three kinds of block type */ | ||
107 | |||
108 | #ifndef LIT_BUFSIZE | ||
109 | # ifdef SMALL_MEM | ||
110 | # define LIT_BUFSIZE 0x2000 | ||
111 | # else | ||
112 | # ifdef MEDIUM_MEM | ||
113 | # define LIT_BUFSIZE 0x4000 | ||
114 | # else | ||
115 | # define LIT_BUFSIZE 0x8000 | ||
116 | # endif | ||
117 | # endif | ||
118 | #endif | ||
119 | #ifndef DIST_BUFSIZE | ||
120 | # define DIST_BUFSIZE LIT_BUFSIZE | ||
121 | #endif | ||
122 | /* Sizes of match buffers for literals/lengths and distances. There are | ||
123 | * 4 reasons for limiting LIT_BUFSIZE to 64K: | ||
124 | * - frequencies can be kept in 16 bit counters | ||
125 | * - if compression is not successful for the first block, all input data is | ||
126 | * still in the window so we can still emit a stored block even when input | ||
127 | * comes from standard input. (This can also be done for all blocks if | ||
128 | * LIT_BUFSIZE is not greater than 32K.) | ||
129 | * - if compression is not successful for a file smaller than 64K, we can | ||
130 | * even emit a stored file instead of a stored block (saving 5 bytes). | ||
131 | * - creating new Huffman trees less frequently may not provide fast | ||
132 | * adaptation to changes in the input data statistics. (Take for | ||
133 | * example a binary file with poorly compressible code followed by | ||
134 | * a highly compressible string table.) Smaller buffer sizes give | ||
135 | * fast adaptation but have of course the overhead of transmitting trees | ||
136 | * more frequently. | ||
137 | * - I can't count above 4 | ||
138 | * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save | ||
139 | * memory at the expense of compression). Some optimizations would be possible | ||
140 | * if we rely on DIST_BUFSIZE == LIT_BUFSIZE. | ||
141 | */ | ||
142 | #if LIT_BUFSIZE > INBUFSIZ | ||
143 | error cannot overlay l_buf and inbuf | ||
144 | #endif | ||
145 | |||
146 | #define REP_3_6 16 | ||
147 | /* repeat previous bit length 3-6 times (2 bits of repeat count) */ | ||
148 | |||
149 | #define REPZ_3_10 17 | ||
150 | /* repeat a zero length 3-10 times (3 bits of repeat count) */ | ||
151 | |||
152 | #define REPZ_11_138 18 | ||
153 | /* repeat a zero length 11-138 times (7 bits of repeat count) */ | ||
154 | |||
155 | /* =========================================================================== | ||
156 | * Local data | ||
157 | */ | ||
158 | |||
159 | /* Data structure describing a single value and its code string. */ | ||
160 | typedef struct ct_data { | ||
161 | union { | ||
162 | ush freq; /* frequency count */ | ||
163 | ush code; /* bit string */ | ||
164 | } fc; | ||
165 | union { | ||
166 | ush dad; /* father node in Huffman tree */ | ||
167 | ush len; /* length of bit string */ | ||
168 | } dl; | ||
169 | } ct_data; | ||
170 | |||
171 | #define Freq fc.freq | ||
172 | #define Code fc.code | ||
173 | #define Dad dl.dad | ||
174 | #define Len dl.len | ||
175 | |||
176 | #define HEAP_SIZE (2*L_CODES+1) | ||
177 | /* maximum heap size */ | ||
178 | |||
179 | local ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */ | ||
180 | local ct_data dyn_dtree[2*D_CODES+1]; /* distance tree */ | ||
181 | |||
182 | local ct_data static_ltree[L_CODES+2]; | ||
183 | /* The static literal tree. Since the bit lengths are imposed, there is no | ||
184 | * need for the L_CODES extra codes used during heap construction. However | ||
185 | * The codes 286 and 287 are needed to build a canonical tree (see ct_init | ||
186 | * below). | ||
187 | */ | ||
188 | |||
189 | local ct_data static_dtree[D_CODES]; | ||
190 | /* The static distance tree. (Actually a trivial tree since all codes use | ||
191 | * 5 bits.) | ||
192 | */ | ||
193 | |||
194 | local ct_data bl_tree[2*BL_CODES+1]; | ||
195 | /* Huffman tree for the bit lengths */ | ||
196 | |||
197 | typedef struct tree_desc { | ||
198 | ct_data *dyn_tree; /* the dynamic tree */ | ||
199 | ct_data *static_tree; /* corresponding static tree or NULL */ | ||
200 | int *extra_bits; /* extra bits for each code or NULL */ | ||
201 | int extra_base; /* base index for extra_bits */ | ||
202 | int elems; /* max number of elements in the tree */ | ||
203 | int max_length; /* max bit length for the codes */ | ||
204 | int max_code; /* largest code with non zero frequency */ | ||
205 | } tree_desc; | ||
206 | |||
207 | local tree_desc l_desc = | ||
208 | {dyn_ltree, static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS, 0}; | ||
209 | |||
210 | local tree_desc d_desc = | ||
211 | {dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0}; | ||
212 | |||
213 | local tree_desc bl_desc = | ||
214 | {bl_tree, (ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS, 0}; | ||
215 | |||
216 | |||
217 | local ush bl_count[MAX_BITS+1]; | ||
218 | /* number of codes at each bit length for an optimal tree */ | ||
219 | |||
220 | local uch bl_order[BL_CODES] | ||
221 | = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; | ||
222 | /* The lengths of the bit length codes are sent in order of decreasing | ||
223 | * probability, to avoid transmitting the lengths for unused bit length codes. | ||
224 | */ | ||
225 | |||
226 | local int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ | ||
227 | local int heap_len; /* number of elements in the heap */ | ||
228 | local int heap_max; /* element of largest frequency */ | ||
229 | /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. | ||
230 | * The same heap array is used to build all trees. | ||
231 | */ | ||
232 | |||
233 | local uch depth[2*L_CODES+1]; | ||
234 | /* Depth of each subtree used as tie breaker for trees of equal frequency */ | ||
235 | |||
236 | local uch length_code[MAX_MATCH-MIN_MATCH+1]; | ||
237 | /* length code for each normalized match length (0 == MIN_MATCH) */ | ||
238 | |||
239 | local uch dist_code[512]; | ||
240 | /* distance codes. The first 256 values correspond to the distances | ||
241 | * 3 .. 258, the last 256 values correspond to the top 8 bits of | ||
242 | * the 15 bit distances. | ||
243 | */ | ||
244 | |||
245 | local int base_length[LENGTH_CODES]; | ||
246 | /* First normalized length for each code (0 = MIN_MATCH) */ | ||
247 | |||
248 | local int base_dist[D_CODES]; | ||
249 | /* First normalized distance for each code (0 = distance of 1) */ | ||
250 | |||
251 | #define l_buf inbuf | ||
252 | /* DECLARE(uch, l_buf, LIT_BUFSIZE); buffer for literals or lengths */ | ||
253 | |||
254 | /* DECLARE(ush, d_buf, DIST_BUFSIZE); buffer for distances */ | ||
255 | |||
256 | local uch flag_buf[(LIT_BUFSIZE/8)]; | ||
257 | /* flag_buf is a bit array distinguishing literals from lengths in | ||
258 | * l_buf, thus indicating the presence or absence of a distance. | ||
259 | */ | ||
260 | |||
261 | local unsigned last_lit; /* running index in l_buf */ | ||
262 | local unsigned last_dist; /* running index in d_buf */ | ||
263 | local unsigned last_flags; /* running index in flag_buf */ | ||
264 | local uch flags; /* current flags not yet saved in flag_buf */ | ||
265 | local uch flag_bit; /* current bit used in flags */ | ||
266 | /* bits are filled in flags starting at bit 0 (least significant). | ||
267 | * Note: these flags are overkill in the current code since we don't | ||
268 | * take advantage of DIST_BUFSIZE == LIT_BUFSIZE. | ||
269 | */ | ||
270 | |||
271 | local ulg opt_len; /* bit length of current block with optimal trees */ | ||
272 | local ulg static_len; /* bit length of current block with static trees */ | ||
273 | |||
274 | local ulg compressed_len; /* total bit length of compressed file */ | ||
275 | |||
276 | local ulg input_len; /* total byte length of input file */ | ||
277 | /* input_len is for debugging only since we can get it by other means. */ | ||
278 | |||
279 | ush *file_type; /* pointer to UNKNOWN, BINARY or ASCII */ | ||
280 | int *file_method; /* pointer to DEFLATE or STORE */ | ||
281 | |||
282 | #ifdef DEBUG | ||
283 | extern ulg bits_sent; /* bit length of the compressed data */ | ||
284 | extern long isize; /* byte length of input file */ | ||
285 | #endif | ||
286 | |||
287 | extern long block_start; /* window offset of current block */ | ||
288 | extern unsigned strstart; /* window offset of current string */ | ||
289 | |||
290 | /* =========================================================================== | ||
291 | * Local (static) routines in this file. | ||
292 | */ | ||
293 | |||
294 | local void init_block OF((void)); | ||
295 | local void pqdownheap OF((ct_data *tree, int k)); | ||
296 | local void gen_bitlen OF((tree_desc *desc)); | ||
297 | local void gen_codes OF((ct_data *tree, int max_code)); | ||
298 | local void build_tree OF((tree_desc *desc)); | ||
299 | local void scan_tree OF((ct_data *tree, int max_code)); | ||
300 | local void send_tree OF((ct_data *tree, int max_code)); | ||
301 | local int build_bl_tree OF((void)); | ||
302 | local void send_all_trees OF((int lcodes, int dcodes, int blcodes)); | ||
303 | local void compress_block OF((ct_data *ltree, ct_data *dtree)); | ||
304 | local void set_file_type OF((void)); | ||
305 | |||
306 | |||
307 | #ifndef DEBUG | ||
308 | # define send_code(c, tree) send_bits(tree[c].Code, tree[c].Len) | ||
309 | /* Send a code of the given tree. c and tree must not have side effects */ | ||
310 | |||
311 | #else /* DEBUG */ | ||
312 | # define send_code(c, tree) \ | ||
313 | { if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \ | ||
314 | send_bits(tree[c].Code, tree[c].Len); } | ||
315 | #endif | ||
316 | |||
317 | #define d_code(dist) \ | ||
318 | ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)]) | ||
319 | /* Mapping from a distance to a distance code. dist is the distance - 1 and | ||
320 | * must not have side effects. dist_code[256] and dist_code[257] are never | ||
321 | * used. | ||
322 | */ | ||
323 | |||
324 | #define MAX(a,b) (a >= b ? a : b) | ||
325 | /* the arguments must not have side effects */ | ||
326 | |||
327 | /* =========================================================================== | ||
328 | * Allocate the match buffer, initialize the various tables and save the | ||
329 | * location of the internal file attribute (ascii/binary) and method | ||
330 | * (DEFLATE/STORE). | ||
331 | */ | ||
332 | void ct_init(attr, methodp) | ||
333 | ush *attr; /* pointer to internal file attribute */ | ||
334 | int *methodp; /* pointer to compression method */ | ||
335 | { | ||
336 | int n; /* iterates over tree elements */ | ||
337 | int bits; /* bit counter */ | ||
338 | int length; /* length value */ | ||
339 | int code; /* code value */ | ||
340 | int dist; /* distance index */ | ||
341 | |||
342 | file_type = attr; | ||
343 | file_method = methodp; | ||
344 | compressed_len = input_len = 0L; | ||
345 | |||
346 | if (static_dtree[0].Len != 0) return; /* ct_init already called */ | ||
347 | |||
348 | /* Initialize the mapping length (0..255) -> length code (0..28) */ | ||
349 | length = 0; | ||
350 | for (code = 0; code < LENGTH_CODES-1; code++) { | ||
351 | base_length[code] = length; | ||
352 | for (n = 0; n < (1<<extra_lbits[code]); n++) { | ||
353 | length_code[length++] = (uch)code; | ||
354 | } | ||
355 | } | ||
356 | Assert (length == 256, "ct_init: length != 256"); | ||
357 | /* Note that the length 255 (match length 258) can be represented | ||
358 | * in two different ways: code 284 + 5 bits or code 285, so we | ||
359 | * overwrite length_code[255] to use the best encoding: | ||
360 | */ | ||
361 | length_code[length-1] = (uch)code; | ||
362 | |||
363 | /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ | ||
364 | dist = 0; | ||
365 | for (code = 0 ; code < 16; code++) { | ||
366 | base_dist[code] = dist; | ||
367 | for (n = 0; n < (1<<extra_dbits[code]); n++) { | ||
368 | dist_code[dist++] = (uch)code; | ||
369 | } | ||
370 | } | ||
371 | Assert (dist == 256, "ct_init: dist != 256"); | ||
372 | dist >>= 7; /* from now on, all distances are divided by 128 */ | ||
373 | for ( ; code < D_CODES; code++) { | ||
374 | base_dist[code] = dist << 7; | ||
375 | for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { | ||
376 | dist_code[256 + dist++] = (uch)code; | ||
377 | } | ||
378 | } | ||
379 | Assert (dist == 256, "ct_init: 256+dist != 512"); | ||
380 | |||
381 | /* Construct the codes of the static literal tree */ | ||
382 | for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; | ||
383 | n = 0; | ||
384 | while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; | ||
385 | while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; | ||
386 | while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; | ||
387 | while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; | ||
388 | /* Codes 286 and 287 do not exist, but we must include them in the | ||
389 | * tree construction to get a canonical Huffman tree (longest code | ||
390 | * all ones) | ||
391 | */ | ||
392 | gen_codes((ct_data *)static_ltree, L_CODES+1); | ||
393 | |||
394 | /* The static distance tree is trivial: */ | ||
395 | for (n = 0; n < D_CODES; n++) { | ||
396 | static_dtree[n].Len = 5; | ||
397 | static_dtree[n].Code = bi_reverse(n, 5); | ||
398 | } | ||
399 | |||
400 | /* Initialize the first block of the first file: */ | ||
401 | init_block(); | ||
402 | } | ||
403 | |||
404 | /* =========================================================================== | ||
405 | * Initialize a new block. | ||
406 | */ | ||
407 | local void init_block() | ||
408 | { | ||
409 | int n; /* iterates over tree elements */ | ||
410 | |||
411 | /* Initialize the trees. */ | ||
412 | for (n = 0; n < L_CODES; n++) dyn_ltree[n].Freq = 0; | ||
413 | for (n = 0; n < D_CODES; n++) dyn_dtree[n].Freq = 0; | ||
414 | for (n = 0; n < BL_CODES; n++) bl_tree[n].Freq = 0; | ||
415 | |||
416 | dyn_ltree[END_BLOCK].Freq = 1; | ||
417 | opt_len = static_len = 0L; | ||
418 | last_lit = last_dist = last_flags = 0; | ||
419 | flags = 0; flag_bit = 1; | ||
420 | } | ||
421 | |||
422 | #define SMALLEST 1 | ||
423 | /* Index within the heap array of least frequent node in the Huffman tree */ | ||
424 | |||
425 | |||
426 | /* =========================================================================== | ||
427 | * Remove the smallest element from the heap and recreate the heap with | ||
428 | * one less element. Updates heap and heap_len. | ||
429 | */ | ||
430 | #define pqremove(tree, top) \ | ||
431 | {\ | ||
432 | top = heap[SMALLEST]; \ | ||
433 | heap[SMALLEST] = heap[heap_len--]; \ | ||
434 | pqdownheap(tree, SMALLEST); \ | ||
435 | } | ||
436 | |||
437 | /* =========================================================================== | ||
438 | * Compares to subtrees, using the tree depth as tie breaker when | ||
439 | * the subtrees have equal frequency. This minimizes the worst case length. | ||
440 | */ | ||
441 | #define smaller(tree, n, m) \ | ||
442 | (tree[n].Freq < tree[m].Freq || \ | ||
443 | (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) | ||
444 | |||
445 | /* =========================================================================== | ||
446 | * Restore the heap property by moving down the tree starting at node k, | ||
447 | * exchanging a node with the smallest of its two sons if necessary, stopping | ||
448 | * when the heap property is re-established (each father smaller than its | ||
449 | * two sons). | ||
450 | */ | ||
451 | local void pqdownheap(tree, k) | ||
452 | ct_data *tree; /* the tree to restore */ | ||
453 | int k; /* node to move down */ | ||
454 | { | ||
455 | int v = heap[k]; | ||
456 | int j = k << 1; /* left son of k */ | ||
457 | while (j <= heap_len) { | ||
458 | /* Set j to the smallest of the two sons: */ | ||
459 | if (j < heap_len && smaller(tree, heap[j+1], heap[j])) j++; | ||
460 | |||
461 | /* Exit if v is smaller than both sons */ | ||
462 | if (smaller(tree, v, heap[j])) break; | ||
463 | |||
464 | /* Exchange v with the smallest son */ | ||
465 | heap[k] = heap[j]; k = j; | ||
466 | |||
467 | /* And continue down the tree, setting j to the left son of k */ | ||
468 | j <<= 1; | ||
469 | } | ||
470 | heap[k] = v; | ||
471 | } | ||
472 | |||
473 | /* =========================================================================== | ||
474 | * Compute the optimal bit lengths for a tree and update the total bit length | ||
475 | * for the current block. | ||
476 | * IN assertion: the fields freq and dad are set, heap[heap_max] and | ||
477 | * above are the tree nodes sorted by increasing frequency. | ||
478 | * OUT assertions: the field len is set to the optimal bit length, the | ||
479 | * array bl_count contains the frequencies for each bit length. | ||
480 | * The length opt_len is updated; static_len is also updated if stree is | ||
481 | * not null. | ||
482 | */ | ||
483 | local void gen_bitlen(desc) | ||
484 | tree_desc *desc; /* the tree descriptor */ | ||
485 | { | ||
486 | ct_data *tree = desc->dyn_tree; | ||
487 | int *extra = desc->extra_bits; | ||
488 | int base = desc->extra_base; | ||
489 | int max_code = desc->max_code; | ||
490 | int max_length = desc->max_length; | ||
491 | ct_data *stree = desc->static_tree; | ||
492 | int h; /* heap index */ | ||
493 | int n, m; /* iterate over the tree elements */ | ||
494 | int bits; /* bit length */ | ||
495 | int xbits; /* extra bits */ | ||
496 | ush f; /* frequency */ | ||
497 | int overflow = 0; /* number of elements with bit length too large */ | ||
498 | |||
499 | for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; | ||
500 | |||
501 | /* In a first pass, compute the optimal bit lengths (which may | ||
502 | * overflow in the case of the bit length tree). | ||
503 | */ | ||
504 | tree[heap[heap_max]].Len = 0; /* root of the heap */ | ||
505 | |||
506 | for (h = heap_max+1; h < HEAP_SIZE; h++) { | ||
507 | n = heap[h]; | ||
508 | bits = tree[tree[n].Dad].Len + 1; | ||
509 | if (bits > max_length) bits = max_length, overflow++; | ||
510 | tree[n].Len = (ush)bits; | ||
511 | /* We overwrite tree[n].Dad which is no longer needed */ | ||
512 | |||
513 | if (n > max_code) continue; /* not a leaf node */ | ||
514 | |||
515 | bl_count[bits]++; | ||
516 | xbits = 0; | ||
517 | if (n >= base) xbits = extra[n-base]; | ||
518 | f = tree[n].Freq; | ||
519 | opt_len += (ulg)f * (bits + xbits); | ||
520 | if (stree) static_len += (ulg)f * (stree[n].Len + xbits); | ||
521 | } | ||
522 | if (overflow == 0) return; | ||
523 | |||
524 | Trace((stderr,"\nbit length overflow\n")); | ||
525 | /* This happens for example on obj2 and pic of the Calgary corpus */ | ||
526 | |||
527 | /* Find the first bit length which could increase: */ | ||
528 | do { | ||
529 | bits = max_length-1; | ||
530 | while (bl_count[bits] == 0) bits--; | ||
531 | bl_count[bits]--; /* move one leaf down the tree */ | ||
532 | bl_count[bits+1] += 2; /* move one overflow item as its brother */ | ||
533 | bl_count[max_length]--; | ||
534 | /* The brother of the overflow item also moves one step up, | ||
535 | * but this does not affect bl_count[max_length] | ||
536 | */ | ||
537 | overflow -= 2; | ||
538 | } while (overflow > 0); | ||
539 | |||
540 | /* Now recompute all bit lengths, scanning in increasing frequency. | ||
541 | * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all | ||
542 | * lengths instead of fixing only the wrong ones. This idea is taken | ||
543 | * from 'ar' written by Haruhiko Okumura.) | ||
544 | */ | ||
545 | for (bits = max_length; bits != 0; bits--) { | ||
546 | n = bl_count[bits]; | ||
547 | while (n != 0) { | ||
548 | m = heap[--h]; | ||
549 | if (m > max_code) continue; | ||
550 | if (tree[m].Len != (unsigned) bits) { | ||
551 | Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); | ||
552 | opt_len += ((long)bits-(long)tree[m].Len)*(long)tree[m].Freq; | ||
553 | tree[m].Len = (ush)bits; | ||
554 | } | ||
555 | n--; | ||
556 | } | ||
557 | } | ||
558 | } | ||
559 | |||
560 | /* =========================================================================== | ||
561 | * Generate the codes for a given tree and bit counts (which need not be | ||
562 | * optimal). | ||
563 | * IN assertion: the array bl_count contains the bit length statistics for | ||
564 | * the given tree and the field len is set for all tree elements. | ||
565 | * OUT assertion: the field code is set for all tree elements of non | ||
566 | * zero code length. | ||
567 | */ | ||
568 | local void gen_codes (tree, max_code) | ||
569 | ct_data *tree; /* the tree to decorate */ | ||
570 | int max_code; /* largest code with non zero frequency */ | ||
571 | { | ||
572 | ush next_code[MAX_BITS+1]; /* next code value for each bit length */ | ||
573 | ush code = 0; /* running code value */ | ||
574 | int bits; /* bit index */ | ||
575 | int n; /* code index */ | ||
576 | |||
577 | /* The distribution counts are first used to generate the code values | ||
578 | * without bit reversal. | ||
579 | */ | ||
580 | for (bits = 1; bits <= MAX_BITS; bits++) { | ||
581 | next_code[bits] = code = (code + bl_count[bits-1]) << 1; | ||
582 | } | ||
583 | /* Check that the bit counts in bl_count are consistent. The last code | ||
584 | * must be all ones. | ||
585 | */ | ||
586 | Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, | ||
587 | "inconsistent bit counts"); | ||
588 | Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); | ||
589 | |||
590 | for (n = 0; n <= max_code; n++) { | ||
591 | int len = tree[n].Len; | ||
592 | if (len == 0) continue; | ||
593 | /* Now reverse the bits */ | ||
594 | tree[n].Code = bi_reverse(next_code[len]++, len); | ||
595 | |||
596 | Tracec(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", | ||
597 | n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); | ||
598 | } | ||
599 | } | ||
600 | |||
601 | /* =========================================================================== | ||
602 | * Construct one Huffman tree and assigns the code bit strings and lengths. | ||
603 | * Update the total bit length for the current block. | ||
604 | * IN assertion: the field freq is set for all tree elements. | ||
605 | * OUT assertions: the fields len and code are set to the optimal bit length | ||
606 | * and corresponding code. The length opt_len is updated; static_len is | ||
607 | * also updated if stree is not null. The field max_code is set. | ||
608 | */ | ||
609 | local void build_tree(desc) | ||
610 | tree_desc *desc; /* the tree descriptor */ | ||
611 | { | ||
612 | ct_data *tree = desc->dyn_tree; | ||
613 | ct_data *stree = desc->static_tree; | ||
614 | int elems = desc->elems; | ||
615 | int n, m; /* iterate over heap elements */ | ||
616 | int max_code = -1; /* largest code with non zero frequency */ | ||
617 | int node = elems; /* next internal node of the tree */ | ||
618 | |||
619 | /* Construct the initial heap, with least frequent element in | ||
620 | * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. | ||
621 | * heap[0] is not used. | ||
622 | */ | ||
623 | heap_len = 0, heap_max = HEAP_SIZE; | ||
624 | |||
625 | for (n = 0; n < elems; n++) { | ||
626 | if (tree[n].Freq != 0) { | ||
627 | heap[++heap_len] = max_code = n; | ||
628 | depth[n] = 0; | ||
629 | } else { | ||
630 | tree[n].Len = 0; | ||
631 | } | ||
632 | } | ||
633 | |||
634 | /* The pkzip format requires that at least one distance code exists, | ||
635 | * and that at least one bit should be sent even if there is only one | ||
636 | * possible code. So to avoid special checks later on we force at least | ||
637 | * two codes of non zero frequency. | ||
638 | */ | ||
639 | while (heap_len < 2) { | ||
640 | int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0); | ||
641 | tree[new].Freq = 1; | ||
642 | depth[new] = 0; | ||
643 | opt_len--; if (stree) static_len -= stree[new].Len; | ||
644 | /* new is 0 or 1 so it does not have extra bits */ | ||
645 | } | ||
646 | desc->max_code = max_code; | ||
647 | |||
648 | /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, | ||
649 | * establish sub-heaps of increasing lengths: | ||
650 | */ | ||
651 | for (n = heap_len/2; n >= 1; n--) pqdownheap(tree, n); | ||
652 | |||
653 | /* Construct the Huffman tree by repeatedly combining the least two | ||
654 | * frequent nodes. | ||
655 | */ | ||
656 | do { | ||
657 | pqremove(tree, n); /* n = node of least frequency */ | ||
658 | m = heap[SMALLEST]; /* m = node of next least frequency */ | ||
659 | |||
660 | heap[--heap_max] = n; /* keep the nodes sorted by frequency */ | ||
661 | heap[--heap_max] = m; | ||
662 | |||
663 | /* Create a new node father of n and m */ | ||
664 | tree[node].Freq = tree[n].Freq + tree[m].Freq; | ||
665 | depth[node] = (uch) (MAX(depth[n], depth[m]) + 1); | ||
666 | tree[n].Dad = tree[m].Dad = (ush)node; | ||
667 | #ifdef DUMP_BL_TREE | ||
668 | if (tree == bl_tree) { | ||
669 | fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", | ||
670 | node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); | ||
671 | } | ||
672 | #endif | ||
673 | /* and insert the new node in the heap */ | ||
674 | heap[SMALLEST] = node++; | ||
675 | pqdownheap(tree, SMALLEST); | ||
676 | |||
677 | } while (heap_len >= 2); | ||
678 | |||
679 | heap[--heap_max] = heap[SMALLEST]; | ||
680 | |||
681 | /* At this point, the fields freq and dad are set. We can now | ||
682 | * generate the bit lengths. | ||
683 | */ | ||
684 | gen_bitlen((tree_desc *)desc); | ||
685 | |||
686 | /* The field len is now set, we can generate the bit codes */ | ||
687 | gen_codes ((ct_data *)tree, max_code); | ||
688 | } | ||
689 | |||
690 | /* =========================================================================== | ||
691 | * Scan a literal or distance tree to determine the frequencies of the codes | ||
692 | * in the bit length tree. Updates opt_len to take into account the repeat | ||
693 | * counts. (The contribution of the bit length codes will be added later | ||
694 | * during the construction of bl_tree.) | ||
695 | */ | ||
696 | local void scan_tree (tree, max_code) | ||
697 | ct_data *tree; /* the tree to be scanned */ | ||
698 | int max_code; /* and its largest code of non zero frequency */ | ||
699 | { | ||
700 | int n; /* iterates over all tree elements */ | ||
701 | int prevlen = -1; /* last emitted length */ | ||
702 | int curlen; /* length of current code */ | ||
703 | int nextlen = tree[0].Len; /* length of next code */ | ||
704 | int count = 0; /* repeat count of the current code */ | ||
705 | int max_count = 7; /* max repeat count */ | ||
706 | int min_count = 4; /* min repeat count */ | ||
707 | |||
708 | if (nextlen == 0) max_count = 138, min_count = 3; | ||
709 | tree[max_code+1].Len = (ush)0xffff; /* guard */ | ||
710 | |||
711 | for (n = 0; n <= max_code; n++) { | ||
712 | curlen = nextlen; nextlen = tree[n+1].Len; | ||
713 | if (++count < max_count && curlen == nextlen) { | ||
714 | continue; | ||
715 | } else if (count < min_count) { | ||
716 | bl_tree[curlen].Freq += count; | ||
717 | } else if (curlen != 0) { | ||
718 | if (curlen != prevlen) bl_tree[curlen].Freq++; | ||
719 | bl_tree[REP_3_6].Freq++; | ||
720 | } else if (count <= 10) { | ||
721 | bl_tree[REPZ_3_10].Freq++; | ||
722 | } else { | ||
723 | bl_tree[REPZ_11_138].Freq++; | ||
724 | } | ||
725 | count = 0; prevlen = curlen; | ||
726 | if (nextlen == 0) { | ||
727 | max_count = 138, min_count = 3; | ||
728 | } else if (curlen == nextlen) { | ||
729 | max_count = 6, min_count = 3; | ||
730 | } else { | ||
731 | max_count = 7, min_count = 4; | ||
732 | } | ||
733 | } | ||
734 | } | ||
735 | |||
736 | /* =========================================================================== | ||
737 | * Send a literal or distance tree in compressed form, using the codes in | ||
738 | * bl_tree. | ||
739 | */ | ||
740 | local void send_tree (tree, max_code) | ||
741 | ct_data *tree; /* the tree to be scanned */ | ||
742 | int max_code; /* and its largest code of non zero frequency */ | ||
743 | { | ||
744 | int n; /* iterates over all tree elements */ | ||
745 | int prevlen = -1; /* last emitted length */ | ||
746 | int curlen; /* length of current code */ | ||
747 | int nextlen = tree[0].Len; /* length of next code */ | ||
748 | int count = 0; /* repeat count of the current code */ | ||
749 | int max_count = 7; /* max repeat count */ | ||
750 | int min_count = 4; /* min repeat count */ | ||
751 | |||
752 | /* tree[max_code+1].Len = -1; */ /* guard already set */ | ||
753 | if (nextlen == 0) max_count = 138, min_count = 3; | ||
754 | |||
755 | for (n = 0; n <= max_code; n++) { | ||
756 | curlen = nextlen; nextlen = tree[n+1].Len; | ||
757 | if (++count < max_count && curlen == nextlen) { | ||
758 | continue; | ||
759 | } else if (count < min_count) { | ||
760 | do { send_code(curlen, bl_tree); } while (--count != 0); | ||
761 | |||
762 | } else if (curlen != 0) { | ||
763 | if (curlen != prevlen) { | ||
764 | send_code(curlen, bl_tree); count--; | ||
765 | } | ||
766 | Assert(count >= 3 && count <= 6, " 3_6?"); | ||
767 | send_code(REP_3_6, bl_tree); send_bits(count-3, 2); | ||
768 | |||
769 | } else if (count <= 10) { | ||
770 | send_code(REPZ_3_10, bl_tree); send_bits(count-3, 3); | ||
771 | |||
772 | } else { | ||
773 | send_code(REPZ_11_138, bl_tree); send_bits(count-11, 7); | ||
774 | } | ||
775 | count = 0; prevlen = curlen; | ||
776 | if (nextlen == 0) { | ||
777 | max_count = 138, min_count = 3; | ||
778 | } else if (curlen == nextlen) { | ||
779 | max_count = 6, min_count = 3; | ||
780 | } else { | ||
781 | max_count = 7, min_count = 4; | ||
782 | } | ||
783 | } | ||
784 | } | ||
785 | |||
786 | /* =========================================================================== | ||
787 | * Construct the Huffman tree for the bit lengths and return the index in | ||
788 | * bl_order of the last bit length code to send. | ||
789 | */ | ||
790 | local int build_bl_tree() | ||
791 | { | ||
792 | int max_blindex; /* index of last bit length code of non zero freq */ | ||
793 | |||
794 | /* Determine the bit length frequencies for literal and distance trees */ | ||
795 | scan_tree((ct_data *)dyn_ltree, l_desc.max_code); | ||
796 | scan_tree((ct_data *)dyn_dtree, d_desc.max_code); | ||
797 | |||
798 | /* Build the bit length tree: */ | ||
799 | build_tree((tree_desc *)(&bl_desc)); | ||
800 | /* opt_len now includes the length of the tree representations, except | ||
801 | * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. | ||
802 | */ | ||
803 | |||
804 | /* Determine the number of bit length codes to send. The pkzip format | ||
805 | * requires that at least 4 bit length codes be sent. (appnote.txt says | ||
806 | * 3 but the actual value used is 4.) | ||
807 | */ | ||
808 | for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { | ||
809 | if (bl_tree[bl_order[max_blindex]].Len != 0) break; | ||
810 | } | ||
811 | /* Update opt_len to include the bit length tree and counts */ | ||
812 | opt_len += 3*(max_blindex+1) + 5+5+4; | ||
813 | Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, static_len)); | ||
814 | |||
815 | return max_blindex; | ||
816 | } | ||
817 | |||
818 | /* =========================================================================== | ||
819 | * Send the header for a block using dynamic Huffman trees: the counts, the | ||
820 | * lengths of the bit length codes, the literal tree and the distance tree. | ||
821 | * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. | ||
822 | */ | ||
823 | local void send_all_trees(lcodes, dcodes, blcodes) | ||
824 | int lcodes, dcodes, blcodes; /* number of codes for each tree */ | ||
825 | { | ||
826 | int rank; /* index in bl_order */ | ||
827 | |||
828 | Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); | ||
829 | Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, | ||
830 | "too many codes"); | ||
831 | Tracev((stderr, "\nbl counts: ")); | ||
832 | send_bits(lcodes-257, 5); /* not +255 as stated in appnote.txt */ | ||
833 | send_bits(dcodes-1, 5); | ||
834 | send_bits(blcodes-4, 4); /* not -3 as stated in appnote.txt */ | ||
835 | for (rank = 0; rank < blcodes; rank++) { | ||
836 | Tracev((stderr, "\nbl code %2d ", bl_order[rank])); | ||
837 | send_bits(bl_tree[bl_order[rank]].Len, 3); | ||
838 | } | ||
839 | Tracev((stderr, "\nbl tree: sent %ld", bits_sent)); | ||
840 | |||
841 | send_tree((ct_data *)dyn_ltree, lcodes-1); /* send the literal tree */ | ||
842 | Tracev((stderr, "\nlit tree: sent %ld", bits_sent)); | ||
843 | |||
844 | send_tree((ct_data *)dyn_dtree, dcodes-1); /* send the distance tree */ | ||
845 | Tracev((stderr, "\ndist tree: sent %ld", bits_sent)); | ||
846 | } | ||
847 | |||
848 | /* =========================================================================== | ||
849 | * Determine the best encoding for the current block: dynamic trees, static | ||
850 | * trees or store, and output the encoded block to the zip file. This function | ||
851 | * returns the total compressed length for the file so far. | ||
852 | */ | ||
853 | ulg flush_block(buf, stored_len, eof) | ||
854 | char *buf; /* input block, or NULL if too old */ | ||
855 | ulg stored_len; /* length of input block */ | ||
856 | int eof; /* true if this is the last block for a file */ | ||
857 | { | ||
858 | ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ | ||
859 | int max_blindex; /* index of last bit length code of non zero freq */ | ||
860 | |||
861 | flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */ | ||
862 | |||
863 | /* Check if the file is ascii or binary */ | ||
864 | if (*file_type == (ush)UNKNOWN) set_file_type(); | ||
865 | |||
866 | /* Construct the literal and distance trees */ | ||
867 | build_tree((tree_desc *)(&l_desc)); | ||
868 | Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len)); | ||
869 | |||
870 | build_tree((tree_desc *)(&d_desc)); | ||
871 | Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, static_len)); | ||
872 | /* At this point, opt_len and static_len are the total bit lengths of | ||
873 | * the compressed block data, excluding the tree representations. | ||
874 | */ | ||
875 | |||
876 | /* Build the bit length tree for the above two trees, and get the index | ||
877 | * in bl_order of the last bit length code to send. | ||
878 | */ | ||
879 | max_blindex = build_bl_tree(); | ||
880 | |||
881 | /* Determine the best encoding. Compute first the block length in bytes */ | ||
882 | opt_lenb = (opt_len+3+7)>>3; | ||
883 | static_lenb = (static_len+3+7)>>3; | ||
884 | input_len += stored_len; /* for debugging only */ | ||
885 | |||
886 | Trace((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ", | ||
887 | opt_lenb, opt_len, static_lenb, static_len, stored_len, | ||
888 | last_lit, last_dist)); | ||
889 | |||
890 | if (static_lenb <= opt_lenb) opt_lenb = static_lenb; | ||
891 | |||
892 | /* If compression failed and this is the first and last block, | ||
893 | * and if the zip file can be seeked (to rewrite the local header), | ||
894 | * the whole file is transformed into a stored file: | ||
895 | */ | ||
896 | #ifdef FORCE_METHOD | ||
897 | if (level == 1 && eof && compressed_len == 0L) { /* force stored file */ | ||
898 | #else | ||
899 | if (stored_len <= opt_lenb && eof && compressed_len == 0L && seekable()) { | ||
900 | #endif | ||
901 | /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ | ||
902 | if (buf == (char*)0) error ("block vanished"); | ||
903 | |||
904 | copy_block(buf, (unsigned)stored_len, 0); /* without header */ | ||
905 | compressed_len = stored_len << 3; | ||
906 | *file_method = STORED; | ||
907 | |||
908 | #ifdef FORCE_METHOD | ||
909 | } else if (level == 2 && buf != (char*)0) { /* force stored block */ | ||
910 | #else | ||
911 | } else if (stored_len+4 <= opt_lenb && buf != (char*)0) { | ||
912 | /* 4: two words for the lengths */ | ||
913 | #endif | ||
914 | /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. | ||
915 | * Otherwise we can't have processed more than WSIZE input bytes since | ||
916 | * the last block flush, because compression would have been | ||
917 | * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to | ||
918 | * transform a block into a stored block. | ||
919 | */ | ||
920 | send_bits((STORED_BLOCK<<1)+eof, 3); /* send block type */ | ||
921 | compressed_len = (compressed_len + 3 + 7) & ~7L; | ||
922 | compressed_len += (stored_len + 4) << 3; | ||
923 | |||
924 | copy_block(buf, (unsigned)stored_len, 1); /* with header */ | ||
925 | |||
926 | #ifdef FORCE_METHOD | ||
927 | } else if (level == 3) { /* force static trees */ | ||
928 | #else | ||
929 | } else if (static_lenb == opt_lenb) { | ||
930 | #endif | ||
931 | send_bits((STATIC_TREES<<1)+eof, 3); | ||
932 | compress_block((ct_data *)static_ltree, (ct_data *)static_dtree); | ||
933 | compressed_len += 3 + static_len; | ||
934 | } else { | ||
935 | send_bits((DYN_TREES<<1)+eof, 3); | ||
936 | send_all_trees(l_desc.max_code+1, d_desc.max_code+1, max_blindex+1); | ||
937 | compress_block((ct_data *)dyn_ltree, (ct_data *)dyn_dtree); | ||
938 | compressed_len += 3 + opt_len; | ||
939 | } | ||
940 | Assert (compressed_len == bits_sent, "bad compressed size"); | ||
941 | init_block(); | ||
942 | |||
943 | if (eof) { | ||
944 | Assert (input_len == isize, "bad input size"); | ||
945 | bi_windup(); | ||
946 | compressed_len += 7; /* align on byte boundary */ | ||
947 | } | ||
948 | Tracev((stderr,"\ncomprlen %lu(%lu) ", compressed_len>>3, | ||
949 | compressed_len-7*eof)); | ||
950 | |||
951 | return compressed_len >> 3; | ||
952 | } | ||
953 | |||
954 | /* =========================================================================== | ||
955 | * Save the match info and tally the frequency counts. Return true if | ||
956 | * the current block must be flushed. | ||
957 | */ | ||
958 | int ct_tally (dist, lc) | ||
959 | int dist; /* distance of matched string */ | ||
960 | int lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ | ||
961 | { | ||
962 | l_buf[last_lit++] = (uch)lc; | ||
963 | if (dist == 0) { | ||
964 | /* lc is the unmatched char */ | ||
965 | dyn_ltree[lc].Freq++; | ||
966 | } else { | ||
967 | /* Here, lc is the match length - MIN_MATCH */ | ||
968 | dist--; /* dist = match distance - 1 */ | ||
969 | Assert((ush)dist < (ush)MAX_DIST && | ||
970 | (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && | ||
971 | (ush)d_code(dist) < (ush)D_CODES, "ct_tally: bad match"); | ||
972 | |||
973 | dyn_ltree[length_code[lc]+LITERALS+1].Freq++; | ||
974 | dyn_dtree[d_code(dist)].Freq++; | ||
975 | |||
976 | d_buf[last_dist++] = (ush)dist; | ||
977 | flags |= flag_bit; | ||
978 | } | ||
979 | flag_bit <<= 1; | ||
980 | |||
981 | /* Output the flags if they fill a byte: */ | ||
982 | if ((last_lit & 7) == 0) { | ||
983 | flag_buf[last_flags++] = flags; | ||
984 | flags = 0, flag_bit = 1; | ||
985 | } | ||
986 | /* Try to guess if it is profitable to stop the current block here */ | ||
987 | if (level > 2 && (last_lit & 0xfff) == 0) { | ||
988 | /* Compute an upper bound for the compressed length */ | ||
989 | ulg out_length = (ulg)last_lit*8L; | ||
990 | ulg in_length = (ulg)strstart-block_start; | ||
991 | int dcode; | ||
992 | for (dcode = 0; dcode < D_CODES; dcode++) { | ||
993 | out_length += (ulg)dyn_dtree[dcode].Freq*(5L+extra_dbits[dcode]); | ||
994 | } | ||
995 | out_length >>= 3; | ||
996 | Trace((stderr,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ", | ||
997 | last_lit, last_dist, in_length, out_length, | ||
998 | 100L - out_length*100L/in_length)); | ||
999 | if (last_dist < last_lit/2 && out_length < in_length/2) return 1; | ||
1000 | } | ||
1001 | return (last_lit == LIT_BUFSIZE-1 || last_dist == DIST_BUFSIZE); | ||
1002 | /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K | ||
1003 | * on 16 bit machines and because stored blocks are restricted to | ||
1004 | * 64K-1 bytes. | ||
1005 | */ | ||
1006 | } | ||
1007 | |||
1008 | /* =========================================================================== | ||
1009 | * Send the block data compressed using the given Huffman trees | ||
1010 | */ | ||
1011 | local void compress_block(ltree, dtree) | ||
1012 | ct_data *ltree; /* literal tree */ | ||
1013 | ct_data *dtree; /* distance tree */ | ||
1014 | { | ||
1015 | unsigned dist; /* distance of matched string */ | ||
1016 | int lc; /* match length or unmatched char (if dist == 0) */ | ||
1017 | unsigned lx = 0; /* running index in l_buf */ | ||
1018 | unsigned dx = 0; /* running index in d_buf */ | ||
1019 | unsigned fx = 0; /* running index in flag_buf */ | ||
1020 | uch flag = 0; /* current flags */ | ||
1021 | unsigned code; /* the code to send */ | ||
1022 | int extra; /* number of extra bits to send */ | ||
1023 | |||
1024 | if (last_lit != 0) do { | ||
1025 | if ((lx & 7) == 0) flag = flag_buf[fx++]; | ||
1026 | lc = l_buf[lx++]; | ||
1027 | if ((flag & 1) == 0) { | ||
1028 | send_code(lc, ltree); /* send a literal byte */ | ||
1029 | Tracecv(isgraph(lc), (stderr," '%c' ", lc)); | ||
1030 | } else { | ||
1031 | /* Here, lc is the match length - MIN_MATCH */ | ||
1032 | code = length_code[lc]; | ||
1033 | send_code(code+LITERALS+1, ltree); /* send the length code */ | ||
1034 | extra = extra_lbits[code]; | ||
1035 | if (extra != 0) { | ||
1036 | lc -= base_length[code]; | ||
1037 | send_bits(lc, extra); /* send the extra length bits */ | ||
1038 | } | ||
1039 | dist = d_buf[dx++]; | ||
1040 | /* Here, dist is the match distance - 1 */ | ||
1041 | code = d_code(dist); | ||
1042 | Assert (code < D_CODES, "bad d_code"); | ||
1043 | |||
1044 | send_code(code, dtree); /* send the distance code */ | ||
1045 | extra = extra_dbits[code]; | ||
1046 | if (extra != 0) { | ||
1047 | dist -= base_dist[code]; | ||
1048 | send_bits(dist, extra); /* send the extra distance bits */ | ||
1049 | } | ||
1050 | } /* literal or match pair ? */ | ||
1051 | flag >>= 1; | ||
1052 | } while (lx < last_lit); | ||
1053 | |||
1054 | send_code(END_BLOCK, ltree); | ||
1055 | } | ||
1056 | |||
1057 | /* =========================================================================== | ||
1058 | * Set the file type to ASCII or BINARY, using a crude approximation: | ||
1059 | * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise. | ||
1060 | * IN assertion: the fields freq of dyn_ltree are set and the total of all | ||
1061 | * frequencies does not exceed 64K (to fit in an int on 16 bit machines). | ||
1062 | */ | ||
1063 | local void set_file_type() | ||
1064 | { | ||
1065 | int n = 0; | ||
1066 | unsigned ascii_freq = 0; | ||
1067 | unsigned bin_freq = 0; | ||
1068 | while (n < 7) bin_freq += dyn_ltree[n++].Freq; | ||
1069 | while (n < 128) ascii_freq += dyn_ltree[n++].Freq; | ||
1070 | while (n < LITERALS) bin_freq += dyn_ltree[n++].Freq; | ||
1071 | *file_type = bin_freq > (ascii_freq >> 2) ? BINARY : ASCII; | ||
1072 | if (*file_type == BINARY && translate_eol) { | ||
1073 | warn("-l used on binary file", ""); | ||
1074 | } | ||
1075 | } |