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3013fe88 NW |
1 | /* 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 | #include <stdio.h> | |
58 | ||
59 | #include "tailor.h" | |
60 | #include "gzip.h" | |
61 | ||
62 | #ifndef lint | |
63 | static char rcsid[] = "$Id: trees.c,v 0.11 1993/03/26 14:55:43 jloup Exp $"; | |
64 | #endif | |
65 | ||
66 | /* =========================================================================== | |
67 | * Constants | |
68 | */ | |
69 | ||
70 | #define MAX_BITS 15 | |
71 | /* All codes must not exceed MAX_BITS bits */ | |
72 | ||
73 | #define MAX_BL_BITS 7 | |
74 | /* Bit length codes must not exceed MAX_BL_BITS bits */ | |
75 | ||
76 | #define LENGTH_CODES 29 | |
77 | /* number of length codes, not counting the special END_BLOCK code */ | |
78 | ||
79 | #define LITERALS 256 | |
80 | /* number of literal bytes 0..255 */ | |
81 | ||
82 | #define END_BLOCK 256 | |
83 | /* end of block literal code */ | |
84 | ||
85 | #define L_CODES (LITERALS+1+LENGTH_CODES) | |
86 | /* number of Literal or Length codes, including the END_BLOCK code */ | |
87 | ||
88 | #define D_CODES 30 | |
89 | /* number of distance codes */ | |
90 | ||
91 | #define BL_CODES 19 | |
92 | /* number of codes used to transfer the bit lengths */ | |
93 | ||
94 | ||
95 | local int near extra_lbits[LENGTH_CODES] /* extra bits for each length code */ | |
96 | = {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}; | |
97 | ||
98 | local int near extra_dbits[D_CODES] /* extra bits for each distance code */ | |
99 | = {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}; | |
100 | ||
101 | local int near extra_blbits[BL_CODES]/* extra bits for each bit length code */ | |
102 | = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; | |
103 | ||
104 | #define STORED_BLOCK 0 | |
105 | #define STATIC_TREES 1 | |
106 | #define DYN_TREES 2 | |
107 | /* The three kinds of block type */ | |
108 | ||
109 | #ifndef LIT_BUFSIZE | |
110 | # ifdef SMALL_MEM | |
111 | # define LIT_BUFSIZE 0x2000 | |
112 | # else | |
113 | # ifdef MEDIUM_MEM | |
114 | # define LIT_BUFSIZE 0x4000 | |
115 | # else | |
116 | # define LIT_BUFSIZE 0x8000 | |
117 | # endif | |
118 | # endif | |
119 | #endif | |
120 | #ifndef DIST_BUFSIZE | |
121 | # define DIST_BUFSIZE LIT_BUFSIZE | |
122 | #endif | |
123 | /* Sizes of match buffers for literals/lengths and distances. There are | |
124 | * 4 reasons for limiting LIT_BUFSIZE to 64K: | |
125 | * - frequencies can be kept in 16 bit counters | |
126 | * - if compression is not successful for the first block, all input data is | |
127 | * still in the window so we can still emit a stored block even when input | |
128 | * comes from standard input. (This can also be done for all blocks if | |
129 | * LIT_BUFSIZE is not greater than 32K.) | |
130 | * - if compression is not successful for a file smaller than 64K, we can | |
131 | * even emit a stored file instead of a stored block (saving 5 bytes). | |
132 | * - creating new Huffman trees less frequently may not provide fast | |
133 | * adaptation to changes in the input data statistics. (Take for | |
134 | * example a binary file with poorly compressible code followed by | |
135 | * a highly compressible string table.) Smaller buffer sizes give | |
136 | * fast adaptation but have of course the overhead of transmitting trees | |
137 | * more frequently. | |
138 | * - I can't count above 4 | |
139 | * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save | |
140 | * memory at the expense of compression). Some optimizations would be possible | |
141 | * if we rely on DIST_BUFSIZE == LIT_BUFSIZE. | |
142 | */ | |
143 | #if LIT_BUFSIZE > INBUFSIZ | |
144 | error cannot overlay l_buf and inbuf | |
145 | #endif | |
146 | ||
147 | #define REP_3_6 16 | |
148 | /* repeat previous bit length 3-6 times (2 bits of repeat count) */ | |
149 | ||
150 | #define REPZ_3_10 17 | |
151 | /* repeat a zero length 3-10 times (3 bits of repeat count) */ | |
152 | ||
153 | #define REPZ_11_138 18 | |
154 | /* repeat a zero length 11-138 times (7 bits of repeat count) */ | |
155 | ||
156 | /* =========================================================================== | |
157 | * Local data | |
158 | */ | |
159 | ||
160 | /* Data structure describing a single value and its code string. */ | |
161 | typedef struct ct_data { | |
162 | union { | |
163 | ush freq; /* frequency count */ | |
164 | ush code; /* bit string */ | |
165 | } fc; | |
166 | union { | |
167 | ush dad; /* father node in Huffman tree */ | |
168 | ush len; /* length of bit string */ | |
169 | } dl; | |
170 | } ct_data; | |
171 | ||
172 | #define Freq fc.freq | |
173 | #define Code fc.code | |
174 | #define Dad dl.dad | |
175 | #define Len dl.len | |
176 | ||
177 | #define HEAP_SIZE (2*L_CODES+1) | |
178 | /* maximum heap size */ | |
179 | ||
180 | local ct_data near dyn_ltree[HEAP_SIZE]; /* literal and length tree */ | |
181 | local ct_data near dyn_dtree[2*D_CODES+1]; /* distance tree */ | |
182 | ||
183 | local ct_data near static_ltree[L_CODES+2]; | |
184 | /* The static literal tree. Since the bit lengths are imposed, there is no | |
185 | * need for the L_CODES extra codes used during heap construction. However | |
186 | * The codes 286 and 287 are needed to build a canonical tree (see ct_init | |
187 | * below). | |
188 | */ | |
189 | ||
190 | local ct_data near static_dtree[D_CODES]; | |
191 | /* The static distance tree. (Actually a trivial tree since all codes use | |
192 | * 5 bits.) | |
193 | */ | |
194 | ||
195 | local ct_data near bl_tree[2*BL_CODES+1]; | |
196 | /* Huffman tree for the bit lengths */ | |
197 | ||
198 | typedef struct tree_desc { | |
199 | ct_data near *dyn_tree; /* the dynamic tree */ | |
200 | ct_data near *static_tree; /* corresponding static tree or NULL */ | |
201 | int near *extra_bits; /* extra bits for each code or NULL */ | |
202 | int extra_base; /* base index for extra_bits */ | |
203 | int elems; /* max number of elements in the tree */ | |
204 | int max_length; /* max bit length for the codes */ | |
205 | int max_code; /* largest code with non zero frequency */ | |
206 | } tree_desc; | |
207 | ||
208 | local tree_desc near l_desc = | |
209 | {dyn_ltree, static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS, 0}; | |
210 | ||
211 | local tree_desc near d_desc = | |
212 | {dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0}; | |
213 | ||
214 | local tree_desc near bl_desc = | |
215 | {bl_tree, (ct_data near *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS, 0}; | |
216 | ||
217 | ||
218 | local ush near bl_count[MAX_BITS+1]; | |
219 | /* number of codes at each bit length for an optimal tree */ | |
220 | ||
221 | local uch near bl_order[BL_CODES] | |
222 | = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; | |
223 | /* The lengths of the bit length codes are sent in order of decreasing | |
224 | * probability, to avoid transmitting the lengths for unused bit length codes. | |
225 | */ | |
226 | ||
227 | local int near heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ | |
228 | local int heap_len; /* number of elements in the heap */ | |
229 | local int heap_max; /* element of largest frequency */ | |
230 | /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. | |
231 | * The same heap array is used to build all trees. | |
232 | */ | |
233 | ||
234 | local uch near depth[2*L_CODES+1]; | |
235 | /* Depth of each subtree used as tie breaker for trees of equal frequency */ | |
236 | ||
237 | local uch length_code[MAX_MATCH-MIN_MATCH+1]; | |
238 | /* length code for each normalized match length (0 == MIN_MATCH) */ | |
239 | ||
240 | local uch dist_code[512]; | |
241 | /* distance codes. The first 256 values correspond to the distances | |
242 | * 3 .. 258, the last 256 values correspond to the top 8 bits of | |
243 | * the 15 bit distances. | |
244 | */ | |
245 | ||
246 | local int near base_length[LENGTH_CODES]; | |
247 | /* First normalized length for each code (0 = MIN_MATCH) */ | |
248 | ||
249 | local int near base_dist[D_CODES]; | |
250 | /* First normalized distance for each code (0 = distance of 1) */ | |
251 | ||
252 | #define l_buf inbuf | |
253 | /* DECLARE(uch, l_buf, LIT_BUFSIZE); buffer for literals or lengths */ | |
254 | ||
255 | /* DECLARE(ush, d_buf, DIST_BUFSIZE); buffer for distances */ | |
256 | ||
257 | local uch near flag_buf[(LIT_BUFSIZE/8)]; | |
258 | /* flag_buf is a bit array distinguishing literals from lengths in | |
259 | * l_buf, thus indicating the presence or absence of a distance. | |
260 | */ | |
261 | ||
262 | local unsigned last_lit; /* running index in l_buf */ | |
263 | local unsigned last_dist; /* running index in d_buf */ | |
264 | local unsigned last_flags; /* running index in flag_buf */ | |
265 | local uch flags; /* current flags not yet saved in flag_buf */ | |
266 | local uch flag_bit; /* current bit used in flags */ | |
267 | /* bits are filled in flags starting at bit 0 (least significant). | |
268 | * Note: these flags are overkill in the current code since we don't | |
269 | * take advantage of DIST_BUFSIZE == LIT_BUFSIZE. | |
270 | */ | |
271 | ||
272 | local ulg opt_len; /* bit length of current block with optimal trees */ | |
273 | local ulg static_len; /* bit length of current block with static trees */ | |
274 | ||
275 | local ulg compressed_len; /* total bit length of compressed file */ | |
276 | ||
277 | local ulg input_len; /* total byte length of input file */ | |
278 | /* input_len is for debugging only since we can get it by other means. */ | |
279 | ||
280 | ush *file_type; /* pointer to UNKNOWN, BINARY or ASCII */ | |
281 | int *file_method; /* pointer to DEFLATE or STORE */ | |
282 | ||
283 | #ifdef DEBUG | |
284 | extern ulg bits_sent; /* bit length of the compressed data */ | |
285 | extern long isize; /* byte length of input file */ | |
286 | #endif | |
287 | ||
288 | extern long block_start; /* window offset of current block */ | |
289 | extern unsigned near strstart; /* window offset of current string */ | |
290 | ||
291 | /* =========================================================================== | |
292 | * Local (static) routines in this file. | |
293 | */ | |
294 | ||
295 | local void init_block OF((void)); | |
296 | local void pqdownheap OF((ct_data near *tree, int k)); | |
297 | local void gen_bitlen OF((tree_desc near *desc)); | |
298 | local void gen_codes OF((ct_data near *tree, int max_code)); | |
299 | local void build_tree OF((tree_desc near *desc)); | |
300 | local void scan_tree OF((ct_data near *tree, int max_code)); | |
301 | local void send_tree OF((ct_data near *tree, int max_code)); | |
302 | local int build_bl_tree OF((void)); | |
303 | local void send_all_trees OF((int lcodes, int dcodes, int blcodes)); | |
304 | local void compress_block OF((ct_data near *ltree, ct_data near *dtree)); | |
305 | local void set_file_type OF((void)); | |
306 | ||
307 | ||
308 | #ifndef DEBUG | |
309 | # define send_code(c, tree) send_bits(tree[c].Code, tree[c].Len) | |
310 | /* Send a code of the given tree. c and tree must not have side effects */ | |
311 | ||
312 | #else /* DEBUG */ | |
313 | # define send_code(c, tree) \ | |
314 | { if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \ | |
315 | send_bits(tree[c].Code, tree[c].Len); } | |
316 | #endif | |
317 | ||
318 | #define d_code(dist) \ | |
319 | ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)]) | |
320 | /* Mapping from a distance to a distance code. dist is the distance - 1 and | |
321 | * must not have side effects. dist_code[256] and dist_code[257] are never | |
322 | * used. | |
323 | */ | |
324 | ||
325 | #define MAX(a,b) (a >= b ? a : b) | |
326 | /* the arguments must not have side effects */ | |
327 | ||
328 | /* =========================================================================== | |
329 | * Allocate the match buffer, initialize the various tables and save the | |
330 | * location of the internal file attribute (ascii/binary) and method | |
331 | * (DEFLATE/STORE). | |
332 | */ | |
333 | void ct_init(attr, methodp) | |
334 | ush *attr; /* pointer to internal file attribute */ | |
335 | int *methodp; /* pointer to compression method */ | |
336 | { | |
337 | int n; /* iterates over tree elements */ | |
338 | int bits; /* bit counter */ | |
339 | int length; /* length value */ | |
340 | int code; /* code value */ | |
341 | int dist; /* distance index */ | |
342 | ||
343 | file_type = attr; | |
344 | file_method = methodp; | |
345 | compressed_len = input_len = 0L; | |
346 | ||
347 | if (static_dtree[0].Len != 0) return; /* ct_init already called */ | |
348 | ||
349 | /* Initialize the mapping length (0..255) -> length code (0..28) */ | |
350 | length = 0; | |
351 | for (code = 0; code < LENGTH_CODES-1; code++) { | |
352 | base_length[code] = length; | |
353 | for (n = 0; n < (1<<extra_lbits[code]); n++) { | |
354 | length_code[length++] = (uch)code; | |
355 | } | |
356 | } | |
357 | Assert (length == 256, "ct_init: length != 256"); | |
358 | /* Note that the length 255 (match length 258) can be represented | |
359 | * in two different ways: code 284 + 5 bits or code 285, so we | |
360 | * overwrite length_code[255] to use the best encoding: | |
361 | */ | |
362 | length_code[length-1] = (uch)code; | |
363 | ||
364 | /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ | |
365 | dist = 0; | |
366 | for (code = 0 ; code < 16; code++) { | |
367 | base_dist[code] = dist; | |
368 | for (n = 0; n < (1<<extra_dbits[code]); n++) { | |
369 | dist_code[dist++] = (uch)code; | |
370 | } | |
371 | } | |
372 | Assert (dist == 256, "ct_init: dist != 256"); | |
373 | dist >>= 7; /* from now on, all distances are divided by 128 */ | |
374 | for ( ; code < D_CODES; code++) { | |
375 | base_dist[code] = dist << 7; | |
376 | for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { | |
377 | dist_code[256 + dist++] = (uch)code; | |
378 | } | |
379 | } | |
380 | Assert (dist == 256, "ct_init: 256+dist != 512"); | |
381 | ||
382 | /* Construct the codes of the static literal tree */ | |
383 | for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; | |
384 | n = 0; | |
385 | while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; | |
386 | while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; | |
387 | while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; | |
388 | while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; | |
389 | /* Codes 286 and 287 do not exist, but we must include them in the | |
390 | * tree construction to get a canonical Huffman tree (longest code | |
391 | * all ones) | |
392 | */ | |
393 | gen_codes((ct_data near *)static_ltree, L_CODES+1); | |
394 | ||
395 | /* The static distance tree is trivial: */ | |
396 | for (n = 0; n < D_CODES; n++) { | |
397 | static_dtree[n].Len = 5; | |
398 | static_dtree[n].Code = bi_reverse(n, 5); | |
399 | } | |
400 | ||
401 | /* Initialize the first block of the first file: */ | |
402 | init_block(); | |
403 | } | |
404 | ||
405 | /* =========================================================================== | |
406 | * Initialize a new block. | |
407 | */ | |
408 | local void init_block() | |
409 | { | |
410 | int n; /* iterates over tree elements */ | |
411 | ||
412 | /* Initialize the trees. */ | |
413 | for (n = 0; n < L_CODES; n++) dyn_ltree[n].Freq = 0; | |
414 | for (n = 0; n < D_CODES; n++) dyn_dtree[n].Freq = 0; | |
415 | for (n = 0; n < BL_CODES; n++) bl_tree[n].Freq = 0; | |
416 | ||
417 | dyn_ltree[END_BLOCK].Freq = 1; | |
418 | opt_len = static_len = 0L; | |
419 | last_lit = last_dist = last_flags = 0; | |
420 | flags = 0; flag_bit = 1; | |
421 | } | |
422 | ||
423 | #define SMALLEST 1 | |
424 | /* Index within the heap array of least frequent node in the Huffman tree */ | |
425 | ||
426 | ||
427 | /* =========================================================================== | |
428 | * Remove the smallest element from the heap and recreate the heap with | |
429 | * one less element. Updates heap and heap_len. | |
430 | */ | |
431 | #define pqremove(tree, top) \ | |
432 | {\ | |
433 | top = heap[SMALLEST]; \ | |
434 | heap[SMALLEST] = heap[heap_len--]; \ | |
435 | pqdownheap(tree, SMALLEST); \ | |
436 | } | |
437 | ||
438 | /* =========================================================================== | |
439 | * Compares to subtrees, using the tree depth as tie breaker when | |
440 | * the subtrees have equal frequency. This minimizes the worst case length. | |
441 | */ | |
442 | #define smaller(tree, n, m) \ | |
443 | (tree[n].Freq < tree[m].Freq || \ | |
444 | (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) | |
445 | ||
446 | /* =========================================================================== | |
447 | * Restore the heap property by moving down the tree starting at node k, | |
448 | * exchanging a node with the smallest of its two sons if necessary, stopping | |
449 | * when the heap property is re-established (each father smaller than its | |
450 | * two sons). | |
451 | */ | |
452 | local void pqdownheap(tree, k) | |
453 | ct_data near *tree; /* the tree to restore */ | |
454 | int k; /* node to move down */ | |
455 | { | |
456 | int v = heap[k]; | |
457 | int j = k << 1; /* left son of k */ | |
458 | while (j <= heap_len) { | |
459 | /* Set j to the smallest of the two sons: */ | |
460 | if (j < heap_len && smaller(tree, heap[j+1], heap[j])) j++; | |
461 | ||
462 | /* Exit if v is smaller than both sons */ | |
463 | if (smaller(tree, v, heap[j])) break; | |
464 | ||
465 | /* Exchange v with the smallest son */ | |
466 | heap[k] = heap[j]; k = j; | |
467 | ||
468 | /* And continue down the tree, setting j to the left son of k */ | |
469 | j <<= 1; | |
470 | } | |
471 | heap[k] = v; | |
472 | } | |
473 | ||
474 | /* =========================================================================== | |
475 | * Compute the optimal bit lengths for a tree and update the total bit length | |
476 | * for the current block. | |
477 | * IN assertion: the fields freq and dad are set, heap[heap_max] and | |
478 | * above are the tree nodes sorted by increasing frequency. | |
479 | * OUT assertions: the field len is set to the optimal bit length, the | |
480 | * array bl_count contains the frequencies for each bit length. | |
481 | * The length opt_len is updated; static_len is also updated if stree is | |
482 | * not null. | |
483 | */ | |
484 | local void gen_bitlen(desc) | |
485 | tree_desc near *desc; /* the tree descriptor */ | |
486 | { | |
487 | ct_data near *tree = desc->dyn_tree; | |
488 | int near *extra = desc->extra_bits; | |
489 | int base = desc->extra_base; | |
490 | int max_code = desc->max_code; | |
491 | int max_length = desc->max_length; | |
492 | ct_data near *stree = desc->static_tree; | |
493 | int h; /* heap index */ | |
494 | int n, m; /* iterate over the tree elements */ | |
495 | int bits; /* bit length */ | |
496 | int xbits; /* extra bits */ | |
497 | ush f; /* frequency */ | |
498 | int overflow = 0; /* number of elements with bit length too large */ | |
499 | ||
500 | for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; | |
501 | ||
502 | /* In a first pass, compute the optimal bit lengths (which may | |
503 | * overflow in the case of the bit length tree). | |
504 | */ | |
505 | tree[heap[heap_max]].Len = 0; /* root of the heap */ | |
506 | ||
507 | for (h = heap_max+1; h < HEAP_SIZE; h++) { | |
508 | n = heap[h]; | |
509 | bits = tree[tree[n].Dad].Len + 1; | |
510 | if (bits > max_length) bits = max_length, overflow++; | |
511 | tree[n].Len = (ush)bits; | |
512 | /* We overwrite tree[n].Dad which is no longer needed */ | |
513 | ||
514 | if (n > max_code) continue; /* not a leaf node */ | |
515 | ||
516 | bl_count[bits]++; | |
517 | xbits = 0; | |
518 | if (n >= base) xbits = extra[n-base]; | |
519 | f = tree[n].Freq; | |
520 | opt_len += (ulg)f * (bits + xbits); | |
521 | if (stree) static_len += (ulg)f * (stree[n].Len + xbits); | |
522 | } | |
523 | if (overflow == 0) return; | |
524 | ||
525 | Trace((stderr,"\nbit length overflow\n")); | |
526 | /* This happens for example on obj2 and pic of the Calgary corpus */ | |
527 | ||
528 | /* Find the first bit length which could increase: */ | |
529 | do { | |
530 | bits = max_length-1; | |
531 | while (bl_count[bits] == 0) bits--; | |
532 | bl_count[bits]--; /* move one leaf down the tree */ | |
533 | bl_count[bits+1] += 2; /* move one overflow item as its brother */ | |
534 | bl_count[max_length]--; | |
535 | /* The brother of the overflow item also moves one step up, | |
536 | * but this does not affect bl_count[max_length] | |
537 | */ | |
538 | overflow -= 2; | |
539 | } while (overflow > 0); | |
540 | ||
541 | /* Now recompute all bit lengths, scanning in increasing frequency. | |
542 | * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all | |
543 | * lengths instead of fixing only the wrong ones. This idea is taken | |
544 | * from 'ar' written by Haruhiko Okumura.) | |
545 | */ | |
546 | for (bits = max_length; bits != 0; bits--) { | |
547 | n = bl_count[bits]; | |
548 | while (n != 0) { | |
549 | m = heap[--h]; | |
550 | if (m > max_code) continue; | |
551 | if (tree[m].Len != (unsigned) bits) { | |
552 | Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); | |
553 | opt_len += ((long)bits-(long)tree[m].Len)*(long)tree[m].Freq; | |
554 | tree[m].Len = (ush)bits; | |
555 | } | |
556 | n--; | |
557 | } | |
558 | } | |
559 | } | |
560 | ||
561 | /* =========================================================================== | |
562 | * Generate the codes for a given tree and bit counts (which need not be | |
563 | * optimal). | |
564 | * IN assertion: the array bl_count contains the bit length statistics for | |
565 | * the given tree and the field len is set for all tree elements. | |
566 | * OUT assertion: the field code is set for all tree elements of non | |
567 | * zero code length. | |
568 | */ | |
569 | local void gen_codes (tree, max_code) | |
570 | ct_data near *tree; /* the tree to decorate */ | |
571 | int max_code; /* largest code with non zero frequency */ | |
572 | { | |
573 | ush next_code[MAX_BITS+1]; /* next code value for each bit length */ | |
574 | ush code = 0; /* running code value */ | |
575 | int bits; /* bit index */ | |
576 | int n; /* code index */ | |
577 | ||
578 | /* The distribution counts are first used to generate the code values | |
579 | * without bit reversal. | |
580 | */ | |
581 | for (bits = 1; bits <= MAX_BITS; bits++) { | |
582 | next_code[bits] = code = (code + bl_count[bits-1]) << 1; | |
583 | } | |
584 | /* Check that the bit counts in bl_count are consistent. The last code | |
585 | * must be all ones. | |
586 | */ | |
587 | Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, | |
588 | "inconsistent bit counts"); | |
589 | Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); | |
590 | ||
591 | for (n = 0; n <= max_code; n++) { | |
592 | int len = tree[n].Len; | |
593 | if (len == 0) continue; | |
594 | /* Now reverse the bits */ | |
595 | tree[n].Code = bi_reverse(next_code[len]++, len); | |
596 | ||
597 | Tracec(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", | |
598 | n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); | |
599 | } | |
600 | } | |
601 | ||
602 | /* =========================================================================== | |
603 | * Construct one Huffman tree and assigns the code bit strings and lengths. | |
604 | * Update the total bit length for the current block. | |
605 | * IN assertion: the field freq is set for all tree elements. | |
606 | * OUT assertions: the fields len and code are set to the optimal bit length | |
607 | * and corresponding code. The length opt_len is updated; static_len is | |
608 | * also updated if stree is not null. The field max_code is set. | |
609 | */ | |
610 | local void build_tree(desc) | |
611 | tree_desc near *desc; /* the tree descriptor */ | |
612 | { | |
613 | ct_data near *tree = desc->dyn_tree; | |
614 | ct_data near *stree = desc->static_tree; | |
615 | int elems = desc->elems; | |
616 | int n, m; /* iterate over heap elements */ | |
617 | int max_code = -1; /* largest code with non zero frequency */ | |
618 | int node = elems; /* next internal node of the tree */ | |
619 | ||
620 | /* Construct the initial heap, with least frequent element in | |
621 | * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. | |
622 | * heap[0] is not used. | |
623 | */ | |
624 | heap_len = 0, heap_max = HEAP_SIZE; | |
625 | ||
626 | for (n = 0; n < elems; n++) { | |
627 | if (tree[n].Freq != 0) { | |
628 | heap[++heap_len] = max_code = n; | |
629 | depth[n] = 0; | |
630 | } else { | |
631 | tree[n].Len = 0; | |
632 | } | |
633 | } | |
634 | ||
635 | /* The pkzip format requires that at least one distance code exists, | |
636 | * and that at least one bit should be sent even if there is only one | |
637 | * possible code. So to avoid special checks later on we force at least | |
638 | * two codes of non zero frequency. | |
639 | */ | |
640 | while (heap_len < 2) { | |
641 | int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0); | |
642 | tree[new].Freq = 1; | |
643 | depth[new] = 0; | |
644 | opt_len--; if (stree) static_len -= stree[new].Len; | |
645 | /* new is 0 or 1 so it does not have extra bits */ | |
646 | } | |
647 | desc->max_code = max_code; | |
648 | ||
649 | /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, | |
650 | * establish sub-heaps of increasing lengths: | |
651 | */ | |
652 | for (n = heap_len/2; n >= 1; n--) pqdownheap(tree, n); | |
653 | ||
654 | /* Construct the Huffman tree by repeatedly combining the least two | |
655 | * frequent nodes. | |
656 | */ | |
657 | do { | |
658 | pqremove(tree, n); /* n = node of least frequency */ | |
659 | m = heap[SMALLEST]; /* m = node of next least frequency */ | |
660 | ||
661 | heap[--heap_max] = n; /* keep the nodes sorted by frequency */ | |
662 | heap[--heap_max] = m; | |
663 | ||
664 | /* Create a new node father of n and m */ | |
665 | tree[node].Freq = tree[n].Freq + tree[m].Freq; | |
666 | depth[node] = (uch) (MAX(depth[n], depth[m]) + 1); | |
667 | tree[n].Dad = tree[m].Dad = (ush)node; | |
668 | #ifdef DUMP_BL_TREE | |
669 | if (tree == bl_tree) { | |
670 | fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", | |
671 | node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); | |
672 | } | |
673 | #endif | |
674 | /* and insert the new node in the heap */ | |
675 | heap[SMALLEST] = node++; | |
676 | pqdownheap(tree, SMALLEST); | |
677 | ||
678 | } while (heap_len >= 2); | |
679 | ||
680 | heap[--heap_max] = heap[SMALLEST]; | |
681 | ||
682 | /* At this point, the fields freq and dad are set. We can now | |
683 | * generate the bit lengths. | |
684 | */ | |
685 | gen_bitlen((tree_desc near *)desc); | |
686 | ||
687 | /* The field len is now set, we can generate the bit codes */ | |
688 | gen_codes ((ct_data near *)tree, max_code); | |
689 | } | |
690 | ||
691 | /* =========================================================================== | |
692 | * Scan a literal or distance tree to determine the frequencies of the codes | |
693 | * in the bit length tree. Updates opt_len to take into account the repeat | |
694 | * counts. (The contribution of the bit length codes will be added later | |
695 | * during the construction of bl_tree.) | |
696 | */ | |
697 | local void scan_tree (tree, max_code) | |
698 | ct_data near *tree; /* the tree to be scanned */ | |
699 | int max_code; /* and its largest code of non zero frequency */ | |
700 | { | |
701 | int n; /* iterates over all tree elements */ | |
702 | int prevlen = -1; /* last emitted length */ | |
703 | int curlen; /* length of current code */ | |
704 | int nextlen = tree[0].Len; /* length of next code */ | |
705 | int count = 0; /* repeat count of the current code */ | |
706 | int max_count = 7; /* max repeat count */ | |
707 | int min_count = 4; /* min repeat count */ | |
708 | ||
709 | if (nextlen == 0) max_count = 138, min_count = 3; | |
710 | tree[max_code+1].Len = (ush)0xffff; /* guard */ | |
711 | ||
712 | for (n = 0; n <= max_code; n++) { | |
713 | curlen = nextlen; nextlen = tree[n+1].Len; | |
714 | if (++count < max_count && curlen == nextlen) { | |
715 | continue; | |
716 | } else if (count < min_count) { | |
717 | bl_tree[curlen].Freq += count; | |
718 | } else if (curlen != 0) { | |
719 | if (curlen != prevlen) bl_tree[curlen].Freq++; | |
720 | bl_tree[REP_3_6].Freq++; | |
721 | } else if (count <= 10) { | |
722 | bl_tree[REPZ_3_10].Freq++; | |
723 | } else { | |
724 | bl_tree[REPZ_11_138].Freq++; | |
725 | } | |
726 | count = 0; prevlen = curlen; | |
727 | if (nextlen == 0) { | |
728 | max_count = 138, min_count = 3; | |
729 | } else if (curlen == nextlen) { | |
730 | max_count = 6, min_count = 3; | |
731 | } else { | |
732 | max_count = 7, min_count = 4; | |
733 | } | |
734 | } | |
735 | } | |
736 | ||
737 | /* =========================================================================== | |
738 | * Send a literal or distance tree in compressed form, using the codes in | |
739 | * bl_tree. | |
740 | */ | |
741 | local void send_tree (tree, max_code) | |
742 | ct_data near *tree; /* the tree to be scanned */ | |
743 | int max_code; /* and its largest code of non zero frequency */ | |
744 | { | |
745 | int n; /* iterates over all tree elements */ | |
746 | int prevlen = -1; /* last emitted length */ | |
747 | int curlen; /* length of current code */ | |
748 | int nextlen = tree[0].Len; /* length of next code */ | |
749 | int count = 0; /* repeat count of the current code */ | |
750 | int max_count = 7; /* max repeat count */ | |
751 | int min_count = 4; /* min repeat count */ | |
752 | ||
753 | /* tree[max_code+1].Len = -1; */ /* guard already set */ | |
754 | if (nextlen == 0) max_count = 138, min_count = 3; | |
755 | ||
756 | for (n = 0; n <= max_code; n++) { | |
757 | curlen = nextlen; nextlen = tree[n+1].Len; | |
758 | if (++count < max_count && curlen == nextlen) { | |
759 | continue; | |
760 | } else if (count < min_count) { | |
761 | do { send_code(curlen, bl_tree); } while (--count != 0); | |
762 | ||
763 | } else if (curlen != 0) { | |
764 | if (curlen != prevlen) { | |
765 | send_code(curlen, bl_tree); count--; | |
766 | } | |
767 | Assert(count >= 3 && count <= 6, " 3_6?"); | |
768 | send_code(REP_3_6, bl_tree); send_bits(count-3, 2); | |
769 | ||
770 | } else if (count <= 10) { | |
771 | send_code(REPZ_3_10, bl_tree); send_bits(count-3, 3); | |
772 | ||
773 | } else { | |
774 | send_code(REPZ_11_138, bl_tree); send_bits(count-11, 7); | |
775 | } | |
776 | count = 0; prevlen = curlen; | |
777 | if (nextlen == 0) { | |
778 | max_count = 138, min_count = 3; | |
779 | } else if (curlen == nextlen) { | |
780 | max_count = 6, min_count = 3; | |
781 | } else { | |
782 | max_count = 7, min_count = 4; | |
783 | } | |
784 | } | |
785 | } | |
786 | ||
787 | /* =========================================================================== | |
788 | * Construct the Huffman tree for the bit lengths and return the index in | |
789 | * bl_order of the last bit length code to send. | |
790 | */ | |
791 | local int build_bl_tree() | |
792 | { | |
793 | int max_blindex; /* index of last bit length code of non zero freq */ | |
794 | ||
795 | /* Determine the bit length frequencies for literal and distance trees */ | |
796 | scan_tree((ct_data near *)dyn_ltree, l_desc.max_code); | |
797 | scan_tree((ct_data near *)dyn_dtree, d_desc.max_code); | |
798 | ||
799 | /* Build the bit length tree: */ | |
800 | build_tree((tree_desc near *)(&bl_desc)); | |
801 | /* opt_len now includes the length of the tree representations, except | |
802 | * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. | |
803 | */ | |
804 | ||
805 | /* Determine the number of bit length codes to send. The pkzip format | |
806 | * requires that at least 4 bit length codes be sent. (appnote.txt says | |
807 | * 3 but the actual value used is 4.) | |
808 | */ | |
809 | for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { | |
810 | if (bl_tree[bl_order[max_blindex]].Len != 0) break; | |
811 | } | |
812 | /* Update opt_len to include the bit length tree and counts */ | |
813 | opt_len += 3*(max_blindex+1) + 5+5+4; | |
814 | Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, static_len)); | |
815 | ||
816 | return max_blindex; | |
817 | } | |
818 | ||
819 | /* =========================================================================== | |
820 | * Send the header for a block using dynamic Huffman trees: the counts, the | |
821 | * lengths of the bit length codes, the literal tree and the distance tree. | |
822 | * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. | |
823 | */ | |
824 | local void send_all_trees(lcodes, dcodes, blcodes) | |
825 | int lcodes, dcodes, blcodes; /* number of codes for each tree */ | |
826 | { | |
827 | int rank; /* index in bl_order */ | |
828 | ||
829 | Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); | |
830 | Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, | |
831 | "too many codes"); | |
832 | Tracev((stderr, "\nbl counts: ")); | |
833 | send_bits(lcodes-257, 5); /* not +255 as stated in appnote.txt */ | |
834 | send_bits(dcodes-1, 5); | |
835 | send_bits(blcodes-4, 4); /* not -3 as stated in appnote.txt */ | |
836 | for (rank = 0; rank < blcodes; rank++) { | |
837 | Tracev((stderr, "\nbl code %2d ", bl_order[rank])); | |
838 | send_bits(bl_tree[bl_order[rank]].Len, 3); | |
839 | } | |
840 | Tracev((stderr, "\nbl tree: sent %ld", bits_sent)); | |
841 | ||
842 | send_tree((ct_data near *)dyn_ltree, lcodes-1); /* send the literal tree */ | |
843 | Tracev((stderr, "\nlit tree: sent %ld", bits_sent)); | |
844 | ||
845 | send_tree((ct_data near *)dyn_dtree, dcodes-1); /* send the distance tree */ | |
846 | Tracev((stderr, "\ndist tree: sent %ld", bits_sent)); | |
847 | } | |
848 | ||
849 | /* =========================================================================== | |
850 | * Determine the best encoding for the current block: dynamic trees, static | |
851 | * trees or store, and output the encoded block to the zip file. This function | |
852 | * returns the total compressed length for the file so far. | |
853 | */ | |
854 | ulg flush_block(buf, stored_len, eof) | |
855 | char *buf; /* input block, or NULL if too old */ | |
856 | ulg stored_len; /* length of input block */ | |
857 | int eof; /* true if this is the last block for a file */ | |
858 | { | |
859 | ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ | |
860 | int max_blindex; /* index of last bit length code of non zero freq */ | |
861 | ||
862 | flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */ | |
863 | ||
864 | /* Check if the file is ascii or binary */ | |
865 | if (*file_type == (ush)UNKNOWN) set_file_type(); | |
866 | ||
867 | /* Construct the literal and distance trees */ | |
868 | build_tree((tree_desc near *)(&l_desc)); | |
869 | Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len)); | |
870 | ||
871 | build_tree((tree_desc near *)(&d_desc)); | |
872 | Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, static_len)); | |
873 | /* At this point, opt_len and static_len are the total bit lengths of | |
874 | * the compressed block data, excluding the tree representations. | |
875 | */ | |
876 | ||
877 | /* Build the bit length tree for the above two trees, and get the index | |
878 | * in bl_order of the last bit length code to send. | |
879 | */ | |
880 | max_blindex = build_bl_tree(); | |
881 | ||
882 | /* Determine the best encoding. Compute first the block length in bytes */ | |
883 | opt_lenb = (opt_len+3+7)>>3; | |
884 | static_lenb = (static_len+3+7)>>3; | |
885 | input_len += stored_len; /* for debugging only */ | |
886 | ||
887 | Trace((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ", | |
888 | opt_lenb, opt_len, static_lenb, static_len, stored_len, | |
889 | last_lit, last_dist)); | |
890 | ||
891 | if (static_lenb <= opt_lenb) opt_lenb = static_lenb; | |
892 | ||
893 | /* If compression failed and this is the first and last block, | |
894 | * and if the zip file can be seeked (to rewrite the local header), | |
895 | * the whole file is transformed into a stored file: | |
896 | */ | |
897 | #ifdef FORCE_METHOD | |
898 | if (level == 1 && eof && compressed_len == 0L) { /* force stored file */ | |
899 | #else | |
900 | if (stored_len <= opt_lenb && eof && compressed_len == 0L && seekable()) { | |
901 | #endif | |
902 | /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ | |
903 | if (buf == (char*)0) error ("block vanished"); | |
904 | ||
905 | copy_block(buf, (unsigned)stored_len, 0); /* without header */ | |
906 | compressed_len = stored_len << 3; | |
907 | *file_method = STORED; | |
908 | ||
909 | #ifdef FORCE_METHOD | |
910 | } else if (level == 2 && buf != (char*)0) { /* force stored block */ | |
911 | #else | |
912 | } else if (stored_len+4 <= opt_lenb && buf != (char*)0) { | |
913 | /* 4: two words for the lengths */ | |
914 | #endif | |
915 | /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. | |
916 | * Otherwise we can't have processed more than WSIZE input bytes since | |
917 | * the last block flush, because compression would have been | |
918 | * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to | |
919 | * transform a block into a stored block. | |
920 | */ | |
921 | send_bits((STORED_BLOCK<<1)+eof, 3); /* send block type */ | |
922 | compressed_len = (compressed_len + 3 + 7) & ~7L; | |
923 | compressed_len += (stored_len + 4) << 3; | |
924 | ||
925 | copy_block(buf, (unsigned)stored_len, 1); /* with header */ | |
926 | ||
927 | #ifdef FORCE_METHOD | |
928 | } else if (level == 3) { /* force static trees */ | |
929 | #else | |
930 | } else if (static_lenb == opt_lenb) { | |
931 | #endif | |
932 | send_bits((STATIC_TREES<<1)+eof, 3); | |
933 | compress_block((ct_data near *)static_ltree, (ct_data near *)static_dtree); | |
934 | compressed_len += 3 + static_len; | |
935 | } else { | |
936 | send_bits((DYN_TREES<<1)+eof, 3); | |
937 | send_all_trees(l_desc.max_code+1, d_desc.max_code+1, max_blindex+1); | |
938 | compress_block((ct_data near *)dyn_ltree, (ct_data near *)dyn_dtree); | |
939 | compressed_len += 3 + opt_len; | |
940 | } | |
941 | Assert (compressed_len == bits_sent, "bad compressed size"); | |
942 | init_block(); | |
943 | ||
944 | if (eof) { | |
945 | Assert (input_len == isize, "bad input size"); | |
946 | bi_windup(); | |
947 | compressed_len += 7; /* align on byte boundary */ | |
948 | } | |
949 | Tracev((stderr,"\ncomprlen %lu(%lu) ", compressed_len>>3, | |
950 | compressed_len-7*eof)); | |
951 | ||
952 | return compressed_len >> 3; | |
953 | } | |
954 | ||
955 | /* =========================================================================== | |
956 | * Save the match info and tally the frequency counts. Return true if | |
957 | * the current block must be flushed. | |
958 | */ | |
959 | int ct_tally (dist, lc) | |
960 | int dist; /* distance of matched string */ | |
961 | int lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ | |
962 | { | |
963 | l_buf[last_lit++] = (uch)lc; | |
964 | if (dist == 0) { | |
965 | /* lc is the unmatched char */ | |
966 | dyn_ltree[lc].Freq++; | |
967 | } else { | |
968 | /* Here, lc is the match length - MIN_MATCH */ | |
969 | dist--; /* dist = match distance - 1 */ | |
970 | Assert((ush)dist < (ush)MAX_DIST && | |
971 | (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && | |
972 | (ush)d_code(dist) < (ush)D_CODES, "ct_tally: bad match"); | |
973 | ||
974 | dyn_ltree[length_code[lc]+LITERALS+1].Freq++; | |
975 | dyn_dtree[d_code(dist)].Freq++; | |
976 | ||
977 | d_buf[last_dist++] = (ush)dist; | |
978 | flags |= flag_bit; | |
979 | } | |
980 | flag_bit <<= 1; | |
981 | ||
982 | /* Output the flags if they fill a byte: */ | |
983 | if ((last_lit & 7) == 0) { | |
984 | flag_buf[last_flags++] = flags; | |
985 | flags = 0, flag_bit = 1; | |
986 | } | |
987 | /* Try to guess if it is profitable to stop the current block here */ | |
988 | if (level > 2 && (last_lit & 0xfff) == 0) { | |
989 | /* Compute an upper bound for the compressed length */ | |
990 | ulg out_length = (ulg)last_lit*8L; | |
991 | ulg in_length = (ulg)strstart-block_start; | |
992 | int dcode; | |
993 | for (dcode = 0; dcode < D_CODES; dcode++) { | |
994 | out_length += (ulg)dyn_dtree[dcode].Freq*(5L+extra_dbits[dcode]); | |
995 | } | |
996 | out_length >>= 3; | |
997 | Trace((stderr,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ", | |
998 | last_lit, last_dist, in_length, out_length, | |
999 | 100L - out_length*100L/in_length)); | |
1000 | if (last_dist < last_lit/2 && out_length < in_length/2) return 1; | |
1001 | } | |
1002 | return (last_lit == LIT_BUFSIZE-1 || last_dist == DIST_BUFSIZE); | |
1003 | /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K | |
1004 | * on 16 bit machines and because stored blocks are restricted to | |
1005 | * 64K-1 bytes. | |
1006 | */ | |
1007 | } | |
1008 | ||
1009 | /* =========================================================================== | |
1010 | * Send the block data compressed using the given Huffman trees | |
1011 | */ | |
1012 | local void compress_block(ltree, dtree) | |
1013 | ct_data near *ltree; /* literal tree */ | |
1014 | ct_data near *dtree; /* distance tree */ | |
1015 | { | |
1016 | unsigned dist; /* distance of matched string */ | |
1017 | int lc; /* match length or unmatched char (if dist == 0) */ | |
1018 | unsigned lx = 0; /* running index in l_buf */ | |
1019 | unsigned dx = 0; /* running index in d_buf */ | |
1020 | unsigned fx = 0; /* running index in flag_buf */ | |
1021 | uch flag = 0; /* current flags */ | |
1022 | unsigned code; /* the code to send */ | |
1023 | int extra; /* number of extra bits to send */ | |
1024 | ||
1025 | if (last_lit != 0) do { | |
1026 | if ((lx & 7) == 0) flag = flag_buf[fx++]; | |
1027 | lc = l_buf[lx++]; | |
1028 | if ((flag & 1) == 0) { | |
1029 | send_code(lc, ltree); /* send a literal byte */ | |
1030 | Tracecv(isgraph(lc), (stderr," '%c' ", lc)); | |
1031 | } else { | |
1032 | /* Here, lc is the match length - MIN_MATCH */ | |
1033 | code = length_code[lc]; | |
1034 | send_code(code+LITERALS+1, ltree); /* send the length code */ | |
1035 | extra = extra_lbits[code]; | |
1036 | if (extra != 0) { | |
1037 | lc -= base_length[code]; | |
1038 | send_bits(lc, extra); /* send the extra length bits */ | |
1039 | } | |
1040 | dist = d_buf[dx++]; | |
1041 | /* Here, dist is the match distance - 1 */ | |
1042 | code = d_code(dist); | |
1043 | Assert (code < D_CODES, "bad d_code"); | |
1044 | ||
1045 | send_code(code, dtree); /* send the distance code */ | |
1046 | extra = extra_dbits[code]; | |
1047 | if (extra != 0) { | |
1048 | dist -= base_dist[code]; | |
1049 | send_bits(dist, extra); /* send the extra distance bits */ | |
1050 | } | |
1051 | } /* literal or match pair ? */ | |
1052 | flag >>= 1; | |
1053 | } while (lx < last_lit); | |
1054 | ||
1055 | send_code(END_BLOCK, ltree); | |
1056 | } | |
1057 | ||
1058 | /* =========================================================================== | |
1059 | * Set the file type to ASCII or BINARY, using a crude approximation: | |
1060 | * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise. | |
1061 | * IN assertion: the fields freq of dyn_ltree are set and the total of all | |
1062 | * frequencies does not exceed 64K (to fit in an int on 16 bit machines). | |
1063 | */ | |
1064 | local void set_file_type() | |
1065 | { | |
1066 | int n = 0; | |
1067 | unsigned ascii_freq = 0; | |
1068 | unsigned bin_freq = 0; | |
1069 | while (n < 7) bin_freq += dyn_ltree[n++].Freq; | |
1070 | while (n < 128) ascii_freq += dyn_ltree[n++].Freq; | |
1071 | while (n < LITERALS) bin_freq += dyn_ltree[n++].Freq; | |
1072 | *file_type = bin_freq > (ascii_freq >> 2) ? BINARY : ASCII; | |
1073 | if (*file_type == BINARY && translate_eol) { | |
1074 | warn("-l used on binary file", ""); | |
1075 | } | |
1076 | } |