1 | /* +++ trees.c */ |
2 | /* trees.c -- output deflated data using Huffman coding |
3 | * Copyright (C) 1995-1996 Jean-loup Gailly |
4 | * For conditions of distribution and use, see copyright notice in zlib.h |
5 | */ |
6 | |
7 | /* |
8 | * ALGORITHM |
9 | * |
10 | * The "deflation" process uses several Huffman trees. The more |
11 | * common source values are represented by shorter bit sequences. |
12 | * |
13 | * Each code tree is stored in a compressed form which is itself |
14 | * a Huffman encoding of the lengths of all the code strings (in |
15 | * ascending order by source values). The actual code strings are |
16 | * reconstructed from the lengths in the inflate process, as described |
17 | * in the deflate specification. |
18 | * |
19 | * REFERENCES |
20 | * |
21 | * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification". |
22 | * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc |
23 | * |
24 | * Storer, James A. |
25 | * Data Compression: Methods and Theory, pp. 49-50. |
26 | * Computer Science Press, 1988. ISBN 0-7167-8156-5. |
27 | * |
28 | * Sedgewick, R. |
29 | * Algorithms, p290. |
30 | * Addison-Wesley, 1983. ISBN 0-201-06672-6. |
31 | */ |
32 | |
33 | /* From: trees.c,v 1.11 1996/07/24 13:41:06 me Exp $ */ |
34 | |
35 | /* #include "deflate.h" */ |
36 | |
37 | #include <linux/zutil.h> |
38 | #include <linux/bitrev.h> |
39 | #include "defutil.h" |
40 | |
41 | #ifdef DEBUG_ZLIB |
42 | # include <ctype.h> |
43 | #endif |
44 | |
45 | /* =========================================================================== |
46 | * Constants |
47 | */ |
48 | |
49 | #define MAX_BL_BITS 7 |
50 | /* Bit length codes must not exceed MAX_BL_BITS bits */ |
51 | |
52 | #define END_BLOCK 256 |
53 | /* end of block literal code */ |
54 | |
55 | #define REP_3_6 16 |
56 | /* repeat previous bit length 3-6 times (2 bits of repeat count) */ |
57 | |
58 | #define REPZ_3_10 17 |
59 | /* repeat a zero length 3-10 times (3 bits of repeat count) */ |
60 | |
61 | #define REPZ_11_138 18 |
62 | /* repeat a zero length 11-138 times (7 bits of repeat count) */ |
63 | |
64 | static const int [LENGTH_CODES] /* extra bits for each length code */ |
65 | = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0}; |
66 | |
67 | static const int [D_CODES] /* extra bits for each distance code */ |
68 | = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13}; |
69 | |
70 | static const int [BL_CODES]/* extra bits for each bit length code */ |
71 | = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; |
72 | |
73 | static const uch bl_order[BL_CODES] |
74 | = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; |
75 | /* The lengths of the bit length codes are sent in order of decreasing |
76 | * probability, to avoid transmitting the lengths for unused bit length codes. |
77 | */ |
78 | |
79 | /* =========================================================================== |
80 | * Local data. These are initialized only once. |
81 | */ |
82 | |
83 | static ct_data static_ltree[L_CODES+2]; |
84 | /* The static literal tree. Since the bit lengths are imposed, there is no |
85 | * need for the L_CODES extra codes used during heap construction. However |
86 | * The codes 286 and 287 are needed to build a canonical tree (see zlib_tr_init |
87 | * below). |
88 | */ |
89 | |
90 | static ct_data static_dtree[D_CODES]; |
91 | /* The static distance tree. (Actually a trivial tree since all codes use |
92 | * 5 bits.) |
93 | */ |
94 | |
95 | static uch dist_code[512]; |
96 | /* distance codes. The first 256 values correspond to the distances |
97 | * 3 .. 258, the last 256 values correspond to the top 8 bits of |
98 | * the 15 bit distances. |
99 | */ |
100 | |
101 | static uch length_code[MAX_MATCH-MIN_MATCH+1]; |
102 | /* length code for each normalized match length (0 == MIN_MATCH) */ |
103 | |
104 | static int base_length[LENGTH_CODES]; |
105 | /* First normalized length for each code (0 = MIN_MATCH) */ |
106 | |
107 | static int base_dist[D_CODES]; |
108 | /* First normalized distance for each code (0 = distance of 1) */ |
109 | |
110 | struct static_tree_desc_s { |
111 | const ct_data *static_tree; /* static tree or NULL */ |
112 | const int *; /* extra bits for each code or NULL */ |
113 | int ; /* base index for extra_bits */ |
114 | int elems; /* max number of elements in the tree */ |
115 | int max_length; /* max bit length for the codes */ |
116 | }; |
117 | |
118 | static static_tree_desc static_l_desc = |
119 | {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; |
120 | |
121 | static static_tree_desc static_d_desc = |
122 | {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; |
123 | |
124 | static static_tree_desc static_bl_desc = |
125 | {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; |
126 | |
127 | /* =========================================================================== |
128 | * Local (static) routines in this file. |
129 | */ |
130 | |
131 | static void tr_static_init (void); |
132 | static void init_block (deflate_state *s); |
133 | static void pqdownheap (deflate_state *s, ct_data *tree, int k); |
134 | static void gen_bitlen (deflate_state *s, tree_desc *desc); |
135 | static void gen_codes (ct_data *tree, int max_code, ush *bl_count); |
136 | static void build_tree (deflate_state *s, tree_desc *desc); |
137 | static void scan_tree (deflate_state *s, ct_data *tree, int max_code); |
138 | static void send_tree (deflate_state *s, ct_data *tree, int max_code); |
139 | static int build_bl_tree (deflate_state *s); |
140 | static void send_all_trees (deflate_state *s, int lcodes, int dcodes, |
141 | int blcodes); |
142 | static void compress_block (deflate_state *s, ct_data *ltree, |
143 | ct_data *dtree); |
144 | static void set_data_type (deflate_state *s); |
145 | static void bi_flush (deflate_state *s); |
146 | static void copy_block (deflate_state *s, char *buf, unsigned len, |
147 | int ); |
148 | |
149 | #ifndef DEBUG_ZLIB |
150 | # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len) |
151 | /* Send a code of the given tree. c and tree must not have side effects */ |
152 | |
153 | #else /* DEBUG_ZLIB */ |
154 | # define send_code(s, c, tree) \ |
155 | { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \ |
156 | send_bits(s, tree[c].Code, tree[c].Len); } |
157 | #endif |
158 | |
159 | #define d_code(dist) \ |
160 | ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)]) |
161 | /* Mapping from a distance to a distance code. dist is the distance - 1 and |
162 | * must not have side effects. dist_code[256] and dist_code[257] are never |
163 | * used. |
164 | */ |
165 | |
166 | /* =========================================================================== |
167 | * Initialize the various 'constant' tables. In a multi-threaded environment, |
168 | * this function may be called by two threads concurrently, but this is |
169 | * harmless since both invocations do exactly the same thing. |
170 | */ |
171 | static void tr_static_init(void) |
172 | { |
173 | static int static_init_done; |
174 | int n; /* iterates over tree elements */ |
175 | int bits; /* bit counter */ |
176 | int length; /* length value */ |
177 | int code; /* code value */ |
178 | int dist; /* distance index */ |
179 | ush bl_count[MAX_BITS+1]; |
180 | /* number of codes at each bit length for an optimal tree */ |
181 | |
182 | if (static_init_done) return; |
183 | |
184 | /* Initialize the mapping length (0..255) -> length code (0..28) */ |
185 | length = 0; |
186 | for (code = 0; code < LENGTH_CODES-1; code++) { |
187 | base_length[code] = length; |
188 | for (n = 0; n < (1<<extra_lbits[code]); n++) { |
189 | length_code[length++] = (uch)code; |
190 | } |
191 | } |
192 | Assert (length == 256, "tr_static_init: length != 256" ); |
193 | /* Note that the length 255 (match length 258) can be represented |
194 | * in two different ways: code 284 + 5 bits or code 285, so we |
195 | * overwrite length_code[255] to use the best encoding: |
196 | */ |
197 | length_code[length-1] = (uch)code; |
198 | |
199 | /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ |
200 | dist = 0; |
201 | for (code = 0 ; code < 16; code++) { |
202 | base_dist[code] = dist; |
203 | for (n = 0; n < (1<<extra_dbits[code]); n++) { |
204 | dist_code[dist++] = (uch)code; |
205 | } |
206 | } |
207 | Assert (dist == 256, "tr_static_init: dist != 256" ); |
208 | dist >>= 7; /* from now on, all distances are divided by 128 */ |
209 | for ( ; code < D_CODES; code++) { |
210 | base_dist[code] = dist << 7; |
211 | for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { |
212 | dist_code[256 + dist++] = (uch)code; |
213 | } |
214 | } |
215 | Assert (dist == 256, "tr_static_init: 256+dist != 512" ); |
216 | |
217 | /* Construct the codes of the static literal tree */ |
218 | for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; |
219 | n = 0; |
220 | while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; |
221 | while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; |
222 | while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; |
223 | while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; |
224 | /* Codes 286 and 287 do not exist, but we must include them in the |
225 | * tree construction to get a canonical Huffman tree (longest code |
226 | * all ones) |
227 | */ |
228 | gen_codes(tree: (ct_data *)static_ltree, L_CODES+1, bl_count); |
229 | |
230 | /* The static distance tree is trivial: */ |
231 | for (n = 0; n < D_CODES; n++) { |
232 | static_dtree[n].Len = 5; |
233 | static_dtree[n].Code = bitrev32((u32)n) >> (32 - 5); |
234 | } |
235 | static_init_done = 1; |
236 | } |
237 | |
238 | /* =========================================================================== |
239 | * Initialize the tree data structures for a new zlib stream. |
240 | */ |
241 | void zlib_tr_init( |
242 | deflate_state *s |
243 | ) |
244 | { |
245 | tr_static_init(); |
246 | |
247 | s->compressed_len = 0L; |
248 | |
249 | s->l_desc.dyn_tree = s->dyn_ltree; |
250 | s->l_desc.stat_desc = &static_l_desc; |
251 | |
252 | s->d_desc.dyn_tree = s->dyn_dtree; |
253 | s->d_desc.stat_desc = &static_d_desc; |
254 | |
255 | s->bl_desc.dyn_tree = s->bl_tree; |
256 | s->bl_desc.stat_desc = &static_bl_desc; |
257 | |
258 | s->bi_buf = 0; |
259 | s->bi_valid = 0; |
260 | s->last_eob_len = 8; /* enough lookahead for inflate */ |
261 | #ifdef DEBUG_ZLIB |
262 | s->bits_sent = 0L; |
263 | #endif |
264 | |
265 | /* Initialize the first block of the first file: */ |
266 | init_block(s); |
267 | } |
268 | |
269 | /* =========================================================================== |
270 | * Initialize a new block. |
271 | */ |
272 | static void init_block( |
273 | deflate_state *s |
274 | ) |
275 | { |
276 | int n; /* iterates over tree elements */ |
277 | |
278 | /* Initialize the trees. */ |
279 | for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0; |
280 | for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0; |
281 | for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0; |
282 | |
283 | s->dyn_ltree[END_BLOCK].Freq = 1; |
284 | s->opt_len = s->static_len = 0L; |
285 | s->last_lit = s->matches = 0; |
286 | } |
287 | |
288 | #define SMALLEST 1 |
289 | /* Index within the heap array of least frequent node in the Huffman tree */ |
290 | |
291 | |
292 | /* =========================================================================== |
293 | * Remove the smallest element from the heap and recreate the heap with |
294 | * one less element. Updates heap and heap_len. |
295 | */ |
296 | #define pqremove(s, tree, top) \ |
297 | {\ |
298 | top = s->heap[SMALLEST]; \ |
299 | s->heap[SMALLEST] = s->heap[s->heap_len--]; \ |
300 | pqdownheap(s, tree, SMALLEST); \ |
301 | } |
302 | |
303 | /* =========================================================================== |
304 | * Compares to subtrees, using the tree depth as tie breaker when |
305 | * the subtrees have equal frequency. This minimizes the worst case length. |
306 | */ |
307 | #define smaller(tree, n, m, depth) \ |
308 | (tree[n].Freq < tree[m].Freq || \ |
309 | (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) |
310 | |
311 | /* =========================================================================== |
312 | * Restore the heap property by moving down the tree starting at node k, |
313 | * exchanging a node with the smallest of its two sons if necessary, stopping |
314 | * when the heap property is re-established (each father smaller than its |
315 | * two sons). |
316 | */ |
317 | static void pqdownheap( |
318 | deflate_state *s, |
319 | ct_data *tree, /* the tree to restore */ |
320 | int k /* node to move down */ |
321 | ) |
322 | { |
323 | int v = s->heap[k]; |
324 | int j = k << 1; /* left son of k */ |
325 | while (j <= s->heap_len) { |
326 | /* Set j to the smallest of the two sons: */ |
327 | if (j < s->heap_len && |
328 | smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { |
329 | j++; |
330 | } |
331 | /* Exit if v is smaller than both sons */ |
332 | if (smaller(tree, v, s->heap[j], s->depth)) break; |
333 | |
334 | /* Exchange v with the smallest son */ |
335 | s->heap[k] = s->heap[j]; k = j; |
336 | |
337 | /* And continue down the tree, setting j to the left son of k */ |
338 | j <<= 1; |
339 | } |
340 | s->heap[k] = v; |
341 | } |
342 | |
343 | /* =========================================================================== |
344 | * Compute the optimal bit lengths for a tree and update the total bit length |
345 | * for the current block. |
346 | * IN assertion: the fields freq and dad are set, heap[heap_max] and |
347 | * above are the tree nodes sorted by increasing frequency. |
348 | * OUT assertions: the field len is set to the optimal bit length, the |
349 | * array bl_count contains the frequencies for each bit length. |
350 | * The length opt_len is updated; static_len is also updated if stree is |
351 | * not null. |
352 | */ |
353 | static void gen_bitlen( |
354 | deflate_state *s, |
355 | tree_desc *desc /* the tree descriptor */ |
356 | ) |
357 | { |
358 | ct_data *tree = desc->dyn_tree; |
359 | int max_code = desc->max_code; |
360 | const ct_data *stree = desc->stat_desc->static_tree; |
361 | const int * = desc->stat_desc->extra_bits; |
362 | int base = desc->stat_desc->extra_base; |
363 | int max_length = desc->stat_desc->max_length; |
364 | int h; /* heap index */ |
365 | int n, m; /* iterate over the tree elements */ |
366 | int bits; /* bit length */ |
367 | int xbits; /* extra bits */ |
368 | ush f; /* frequency */ |
369 | int overflow = 0; /* number of elements with bit length too large */ |
370 | |
371 | for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0; |
372 | |
373 | /* In a first pass, compute the optimal bit lengths (which may |
374 | * overflow in the case of the bit length tree). |
375 | */ |
376 | tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ |
377 | |
378 | for (h = s->heap_max+1; h < HEAP_SIZE; h++) { |
379 | n = s->heap[h]; |
380 | bits = tree[tree[n].Dad].Len + 1; |
381 | if (bits > max_length) bits = max_length, overflow++; |
382 | tree[n].Len = (ush)bits; |
383 | /* We overwrite tree[n].Dad which is no longer needed */ |
384 | |
385 | if (n > max_code) continue; /* not a leaf node */ |
386 | |
387 | s->bl_count[bits]++; |
388 | xbits = 0; |
389 | if (n >= base) xbits = extra[n-base]; |
390 | f = tree[n].Freq; |
391 | s->opt_len += (ulg)f * (bits + xbits); |
392 | if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits); |
393 | } |
394 | if (overflow == 0) return; |
395 | |
396 | Trace((stderr,"\nbit length overflow\n" )); |
397 | /* This happens for example on obj2 and pic of the Calgary corpus */ |
398 | |
399 | /* Find the first bit length which could increase: */ |
400 | do { |
401 | bits = max_length-1; |
402 | while (s->bl_count[bits] == 0) bits--; |
403 | s->bl_count[bits]--; /* move one leaf down the tree */ |
404 | s->bl_count[bits+1] += 2; /* move one overflow item as its brother */ |
405 | s->bl_count[max_length]--; |
406 | /* The brother of the overflow item also moves one step up, |
407 | * but this does not affect bl_count[max_length] |
408 | */ |
409 | overflow -= 2; |
410 | } while (overflow > 0); |
411 | |
412 | /* Now recompute all bit lengths, scanning in increasing frequency. |
413 | * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all |
414 | * lengths instead of fixing only the wrong ones. This idea is taken |
415 | * from 'ar' written by Haruhiko Okumura.) |
416 | */ |
417 | for (bits = max_length; bits != 0; bits--) { |
418 | n = s->bl_count[bits]; |
419 | while (n != 0) { |
420 | m = s->heap[--h]; |
421 | if (m > max_code) continue; |
422 | if (tree[m].Len != (unsigned) bits) { |
423 | Trace((stderr,"code %d bits %d->%d\n" , m, tree[m].Len, bits)); |
424 | s->opt_len += ((long)bits - (long)tree[m].Len) |
425 | *(long)tree[m].Freq; |
426 | tree[m].Len = (ush)bits; |
427 | } |
428 | n--; |
429 | } |
430 | } |
431 | } |
432 | |
433 | /* =========================================================================== |
434 | * Generate the codes for a given tree and bit counts (which need not be |
435 | * optimal). |
436 | * IN assertion: the array bl_count contains the bit length statistics for |
437 | * the given tree and the field len is set for all tree elements. |
438 | * OUT assertion: the field code is set for all tree elements of non |
439 | * zero code length. |
440 | */ |
441 | static void gen_codes( |
442 | ct_data *tree, /* the tree to decorate */ |
443 | int max_code, /* largest code with non zero frequency */ |
444 | ush *bl_count /* number of codes at each bit length */ |
445 | ) |
446 | { |
447 | ush next_code[MAX_BITS+1]; /* next code value for each bit length */ |
448 | ush code = 0; /* running code value */ |
449 | int bits; /* bit index */ |
450 | int n; /* code index */ |
451 | |
452 | /* The distribution counts are first used to generate the code values |
453 | * without bit reversal. |
454 | */ |
455 | for (bits = 1; bits <= MAX_BITS; bits++) { |
456 | next_code[bits] = code = (code + bl_count[bits-1]) << 1; |
457 | } |
458 | /* Check that the bit counts in bl_count are consistent. The last code |
459 | * must be all ones. |
460 | */ |
461 | Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, |
462 | "inconsistent bit counts" ); |
463 | Tracev((stderr,"\ngen_codes: max_code %d " , max_code)); |
464 | |
465 | for (n = 0; n <= max_code; n++) { |
466 | int len = tree[n].Len; |
467 | if (len == 0) continue; |
468 | /* Now reverse the bits */ |
469 | tree[n].Code = bitrev32((u32)(next_code[len]++)) >> (32 - len); |
470 | |
471 | Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) " , |
472 | n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); |
473 | } |
474 | } |
475 | |
476 | /* =========================================================================== |
477 | * Construct one Huffman tree and assigns the code bit strings and lengths. |
478 | * Update the total bit length for the current block. |
479 | * IN assertion: the field freq is set for all tree elements. |
480 | * OUT assertions: the fields len and code are set to the optimal bit length |
481 | * and corresponding code. The length opt_len is updated; static_len is |
482 | * also updated if stree is not null. The field max_code is set. |
483 | */ |
484 | static void build_tree( |
485 | deflate_state *s, |
486 | tree_desc *desc /* the tree descriptor */ |
487 | ) |
488 | { |
489 | ct_data *tree = desc->dyn_tree; |
490 | const ct_data *stree = desc->stat_desc->static_tree; |
491 | int elems = desc->stat_desc->elems; |
492 | int n, m; /* iterate over heap elements */ |
493 | int max_code = -1; /* largest code with non zero frequency */ |
494 | int node; /* new node being created */ |
495 | |
496 | /* Construct the initial heap, with least frequent element in |
497 | * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. |
498 | * heap[0] is not used. |
499 | */ |
500 | s->heap_len = 0, s->heap_max = HEAP_SIZE; |
501 | |
502 | for (n = 0; n < elems; n++) { |
503 | if (tree[n].Freq != 0) { |
504 | s->heap[++(s->heap_len)] = max_code = n; |
505 | s->depth[n] = 0; |
506 | } else { |
507 | tree[n].Len = 0; |
508 | } |
509 | } |
510 | |
511 | /* The pkzip format requires that at least one distance code exists, |
512 | * and that at least one bit should be sent even if there is only one |
513 | * possible code. So to avoid special checks later on we force at least |
514 | * two codes of non zero frequency. |
515 | */ |
516 | while (s->heap_len < 2) { |
517 | node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0); |
518 | tree[node].Freq = 1; |
519 | s->depth[node] = 0; |
520 | s->opt_len--; if (stree) s->static_len -= stree[node].Len; |
521 | /* node is 0 or 1 so it does not have extra bits */ |
522 | } |
523 | desc->max_code = max_code; |
524 | |
525 | /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, |
526 | * establish sub-heaps of increasing lengths: |
527 | */ |
528 | for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, k: n); |
529 | |
530 | /* Construct the Huffman tree by repeatedly combining the least two |
531 | * frequent nodes. |
532 | */ |
533 | node = elems; /* next internal node of the tree */ |
534 | do { |
535 | pqremove(s, tree, n); /* n = node of least frequency */ |
536 | m = s->heap[SMALLEST]; /* m = node of next least frequency */ |
537 | |
538 | s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */ |
539 | s->heap[--(s->heap_max)] = m; |
540 | |
541 | /* Create a new node father of n and m */ |
542 | tree[node].Freq = tree[n].Freq + tree[m].Freq; |
543 | s->depth[node] = (uch) (max(s->depth[n], s->depth[m]) + 1); |
544 | tree[n].Dad = tree[m].Dad = (ush)node; |
545 | #ifdef DUMP_BL_TREE |
546 | if (tree == s->bl_tree) { |
547 | fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)" , |
548 | node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); |
549 | } |
550 | #endif |
551 | /* and insert the new node in the heap */ |
552 | s->heap[SMALLEST] = node++; |
553 | pqdownheap(s, tree, SMALLEST); |
554 | |
555 | } while (s->heap_len >= 2); |
556 | |
557 | s->heap[--(s->heap_max)] = s->heap[SMALLEST]; |
558 | |
559 | /* At this point, the fields freq and dad are set. We can now |
560 | * generate the bit lengths. |
561 | */ |
562 | gen_bitlen(s, desc: (tree_desc *)desc); |
563 | |
564 | /* The field len is now set, we can generate the bit codes */ |
565 | gen_codes (tree: (ct_data *)tree, max_code, bl_count: s->bl_count); |
566 | } |
567 | |
568 | /* =========================================================================== |
569 | * Scan a literal or distance tree to determine the frequencies of the codes |
570 | * in the bit length tree. |
571 | */ |
572 | static void scan_tree( |
573 | deflate_state *s, |
574 | ct_data *tree, /* the tree to be scanned */ |
575 | int max_code /* and its largest code of non zero frequency */ |
576 | ) |
577 | { |
578 | int n; /* iterates over all tree elements */ |
579 | int prevlen = -1; /* last emitted length */ |
580 | int curlen; /* length of current code */ |
581 | int nextlen = tree[0].Len; /* length of next code */ |
582 | int count = 0; /* repeat count of the current code */ |
583 | int max_count = 7; /* max repeat count */ |
584 | int min_count = 4; /* min repeat count */ |
585 | |
586 | if (nextlen == 0) max_count = 138, min_count = 3; |
587 | tree[max_code+1].Len = (ush)0xffff; /* guard */ |
588 | |
589 | for (n = 0; n <= max_code; n++) { |
590 | curlen = nextlen; nextlen = tree[n+1].Len; |
591 | if (++count < max_count && curlen == nextlen) { |
592 | continue; |
593 | } else if (count < min_count) { |
594 | s->bl_tree[curlen].Freq += count; |
595 | } else if (curlen != 0) { |
596 | if (curlen != prevlen) s->bl_tree[curlen].Freq++; |
597 | s->bl_tree[REP_3_6].Freq++; |
598 | } else if (count <= 10) { |
599 | s->bl_tree[REPZ_3_10].Freq++; |
600 | } else { |
601 | s->bl_tree[REPZ_11_138].Freq++; |
602 | } |
603 | count = 0; prevlen = curlen; |
604 | if (nextlen == 0) { |
605 | max_count = 138, min_count = 3; |
606 | } else if (curlen == nextlen) { |
607 | max_count = 6, min_count = 3; |
608 | } else { |
609 | max_count = 7, min_count = 4; |
610 | } |
611 | } |
612 | } |
613 | |
614 | /* =========================================================================== |
615 | * Send a literal or distance tree in compressed form, using the codes in |
616 | * bl_tree. |
617 | */ |
618 | static void send_tree( |
619 | deflate_state *s, |
620 | ct_data *tree, /* the tree to be scanned */ |
621 | int max_code /* and its largest code of non zero frequency */ |
622 | ) |
623 | { |
624 | int n; /* iterates over all tree elements */ |
625 | int prevlen = -1; /* last emitted length */ |
626 | int curlen; /* length of current code */ |
627 | int nextlen = tree[0].Len; /* length of next code */ |
628 | int count = 0; /* repeat count of the current code */ |
629 | int max_count = 7; /* max repeat count */ |
630 | int min_count = 4; /* min repeat count */ |
631 | |
632 | /* tree[max_code+1].Len = -1; */ /* guard already set */ |
633 | if (nextlen == 0) max_count = 138, min_count = 3; |
634 | |
635 | for (n = 0; n <= max_code; n++) { |
636 | curlen = nextlen; nextlen = tree[n+1].Len; |
637 | if (++count < max_count && curlen == nextlen) { |
638 | continue; |
639 | } else if (count < min_count) { |
640 | do { send_code(s, curlen, s->bl_tree); } while (--count != 0); |
641 | |
642 | } else if (curlen != 0) { |
643 | if (curlen != prevlen) { |
644 | send_code(s, curlen, s->bl_tree); count--; |
645 | } |
646 | Assert(count >= 3 && count <= 6, " 3_6?" ); |
647 | send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2); |
648 | |
649 | } else if (count <= 10) { |
650 | send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3); |
651 | |
652 | } else { |
653 | send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7); |
654 | } |
655 | count = 0; prevlen = curlen; |
656 | if (nextlen == 0) { |
657 | max_count = 138, min_count = 3; |
658 | } else if (curlen == nextlen) { |
659 | max_count = 6, min_count = 3; |
660 | } else { |
661 | max_count = 7, min_count = 4; |
662 | } |
663 | } |
664 | } |
665 | |
666 | /* =========================================================================== |
667 | * Construct the Huffman tree for the bit lengths and return the index in |
668 | * bl_order of the last bit length code to send. |
669 | */ |
670 | static int build_bl_tree( |
671 | deflate_state *s |
672 | ) |
673 | { |
674 | int max_blindex; /* index of last bit length code of non zero freq */ |
675 | |
676 | /* Determine the bit length frequencies for literal and distance trees */ |
677 | scan_tree(s, tree: (ct_data *)s->dyn_ltree, max_code: s->l_desc.max_code); |
678 | scan_tree(s, tree: (ct_data *)s->dyn_dtree, max_code: s->d_desc.max_code); |
679 | |
680 | /* Build the bit length tree: */ |
681 | build_tree(s, desc: (tree_desc *)(&(s->bl_desc))); |
682 | /* opt_len now includes the length of the tree representations, except |
683 | * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. |
684 | */ |
685 | |
686 | /* Determine the number of bit length codes to send. The pkzip format |
687 | * requires that at least 4 bit length codes be sent. (appnote.txt says |
688 | * 3 but the actual value used is 4.) |
689 | */ |
690 | for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { |
691 | if (s->bl_tree[bl_order[max_blindex]].Len != 0) break; |
692 | } |
693 | /* Update opt_len to include the bit length tree and counts */ |
694 | s->opt_len += 3*(max_blindex+1) + 5+5+4; |
695 | Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld" , |
696 | s->opt_len, s->static_len)); |
697 | |
698 | return max_blindex; |
699 | } |
700 | |
701 | /* =========================================================================== |
702 | * Send the header for a block using dynamic Huffman trees: the counts, the |
703 | * lengths of the bit length codes, the literal tree and the distance tree. |
704 | * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. |
705 | */ |
706 | static void send_all_trees( |
707 | deflate_state *s, |
708 | int lcodes, /* number of codes for each tree */ |
709 | int dcodes, /* number of codes for each tree */ |
710 | int blcodes /* number of codes for each tree */ |
711 | ) |
712 | { |
713 | int rank; /* index in bl_order */ |
714 | |
715 | Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes" ); |
716 | Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, |
717 | "too many codes" ); |
718 | Tracev((stderr, "\nbl counts: " )); |
719 | send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */ |
720 | send_bits(s, dcodes-1, 5); |
721 | send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */ |
722 | for (rank = 0; rank < blcodes; rank++) { |
723 | Tracev((stderr, "\nbl code %2d " , bl_order[rank])); |
724 | send_bits(s, s->bl_tree[bl_order[rank]].Len, 3); |
725 | } |
726 | Tracev((stderr, "\nbl tree: sent %ld" , s->bits_sent)); |
727 | |
728 | send_tree(s, tree: (ct_data *)s->dyn_ltree, max_code: lcodes-1); /* literal tree */ |
729 | Tracev((stderr, "\nlit tree: sent %ld" , s->bits_sent)); |
730 | |
731 | send_tree(s, tree: (ct_data *)s->dyn_dtree, max_code: dcodes-1); /* distance tree */ |
732 | Tracev((stderr, "\ndist tree: sent %ld" , s->bits_sent)); |
733 | } |
734 | |
735 | /* =========================================================================== |
736 | * Send a stored block |
737 | */ |
738 | void zlib_tr_stored_block( |
739 | deflate_state *s, |
740 | char *buf, /* input block */ |
741 | ulg stored_len, /* length of input block */ |
742 | int eof /* true if this is the last block for a file */ |
743 | ) |
744 | { |
745 | send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */ |
746 | s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L; |
747 | s->compressed_len += (stored_len + 4) << 3; |
748 | |
749 | copy_block(s, buf, len: (unsigned)stored_len, header: 1); /* with header */ |
750 | } |
751 | |
752 | /* Send just the `stored block' type code without any length bytes or data. |
753 | */ |
754 | void zlib_tr_stored_type_only( |
755 | deflate_state *s |
756 | ) |
757 | { |
758 | send_bits(s, (STORED_BLOCK << 1), 3); |
759 | bi_windup(s); |
760 | s->compressed_len = (s->compressed_len + 3) & ~7L; |
761 | } |
762 | |
763 | |
764 | /* =========================================================================== |
765 | * Send one empty static block to give enough lookahead for inflate. |
766 | * This takes 10 bits, of which 7 may remain in the bit buffer. |
767 | * The current inflate code requires 9 bits of lookahead. If the |
768 | * last two codes for the previous block (real code plus EOB) were coded |
769 | * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode |
770 | * the last real code. In this case we send two empty static blocks instead |
771 | * of one. (There are no problems if the previous block is stored or fixed.) |
772 | * To simplify the code, we assume the worst case of last real code encoded |
773 | * on one bit only. |
774 | */ |
775 | void zlib_tr_align( |
776 | deflate_state *s |
777 | ) |
778 | { |
779 | send_bits(s, STATIC_TREES<<1, 3); |
780 | send_code(s, END_BLOCK, static_ltree); |
781 | s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ |
782 | bi_flush(s); |
783 | /* Of the 10 bits for the empty block, we have already sent |
784 | * (10 - bi_valid) bits. The lookahead for the last real code (before |
785 | * the EOB of the previous block) was thus at least one plus the length |
786 | * of the EOB plus what we have just sent of the empty static block. |
787 | */ |
788 | if (1 + s->last_eob_len + 10 - s->bi_valid < 9) { |
789 | send_bits(s, STATIC_TREES<<1, 3); |
790 | send_code(s, END_BLOCK, static_ltree); |
791 | s->compressed_len += 10L; |
792 | bi_flush(s); |
793 | } |
794 | s->last_eob_len = 7; |
795 | } |
796 | |
797 | /* =========================================================================== |
798 | * Determine the best encoding for the current block: dynamic trees, static |
799 | * trees or store, and output the encoded block to the zip file. This function |
800 | * returns the total compressed length for the file so far. |
801 | */ |
802 | ulg zlib_tr_flush_block( |
803 | deflate_state *s, |
804 | char *buf, /* input block, or NULL if too old */ |
805 | ulg stored_len, /* length of input block */ |
806 | int eof /* true if this is the last block for a file */ |
807 | ) |
808 | { |
809 | ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ |
810 | int max_blindex = 0; /* index of last bit length code of non zero freq */ |
811 | |
812 | /* Build the Huffman trees unless a stored block is forced */ |
813 | if (s->level > 0) { |
814 | |
815 | /* Check if the file is ascii or binary */ |
816 | if (s->data_type == Z_UNKNOWN) set_data_type(s); |
817 | |
818 | /* Construct the literal and distance trees */ |
819 | build_tree(s, desc: (tree_desc *)(&(s->l_desc))); |
820 | Tracev((stderr, "\nlit data: dyn %ld, stat %ld" , s->opt_len, |
821 | s->static_len)); |
822 | |
823 | build_tree(s, desc: (tree_desc *)(&(s->d_desc))); |
824 | Tracev((stderr, "\ndist data: dyn %ld, stat %ld" , s->opt_len, |
825 | s->static_len)); |
826 | /* At this point, opt_len and static_len are the total bit lengths of |
827 | * the compressed block data, excluding the tree representations. |
828 | */ |
829 | |
830 | /* Build the bit length tree for the above two trees, and get the index |
831 | * in bl_order of the last bit length code to send. |
832 | */ |
833 | max_blindex = build_bl_tree(s); |
834 | |
835 | /* Determine the best encoding. Compute first the block length in bytes*/ |
836 | opt_lenb = (s->opt_len+3+7)>>3; |
837 | static_lenb = (s->static_len+3+7)>>3; |
838 | |
839 | Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u " , |
840 | opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, |
841 | s->last_lit)); |
842 | |
843 | if (static_lenb <= opt_lenb) opt_lenb = static_lenb; |
844 | |
845 | } else { |
846 | Assert(buf != (char*)0, "lost buf" ); |
847 | opt_lenb = static_lenb = stored_len + 5; /* force a stored block */ |
848 | } |
849 | |
850 | /* If compression failed and this is the first and last block, |
851 | * and if the .zip file can be seeked (to rewrite the local header), |
852 | * the whole file is transformed into a stored file: |
853 | */ |
854 | #ifdef STORED_FILE_OK |
855 | # ifdef FORCE_STORED_FILE |
856 | if (eof && s->compressed_len == 0L) { /* force stored file */ |
857 | # else |
858 | if (stored_len <= opt_lenb && eof && s->compressed_len==0L && seekable()) { |
859 | # endif |
860 | /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ |
861 | if (buf == (char*)0) error ("block vanished" ); |
862 | |
863 | copy_block(s, buf, (unsigned)stored_len, 0); /* without header */ |
864 | s->compressed_len = stored_len << 3; |
865 | s->method = STORED; |
866 | } else |
867 | #endif /* STORED_FILE_OK */ |
868 | |
869 | #ifdef FORCE_STORED |
870 | if (buf != (char*)0) { /* force stored block */ |
871 | #else |
872 | if (stored_len+4 <= opt_lenb && buf != (char*)0) { |
873 | /* 4: two words for the lengths */ |
874 | #endif |
875 | /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. |
876 | * Otherwise we can't have processed more than WSIZE input bytes since |
877 | * the last block flush, because compression would have been |
878 | * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to |
879 | * transform a block into a stored block. |
880 | */ |
881 | zlib_tr_stored_block(s, buf, stored_len, eof); |
882 | |
883 | #ifdef FORCE_STATIC |
884 | } else if (static_lenb >= 0) { /* force static trees */ |
885 | #else |
886 | } else if (static_lenb == opt_lenb) { |
887 | #endif |
888 | send_bits(s, (STATIC_TREES<<1)+eof, 3); |
889 | compress_block(s, ltree: (ct_data *)static_ltree, dtree: (ct_data *)static_dtree); |
890 | s->compressed_len += 3 + s->static_len; |
891 | } else { |
892 | send_bits(s, (DYN_TREES<<1)+eof, 3); |
893 | send_all_trees(s, lcodes: s->l_desc.max_code+1, dcodes: s->d_desc.max_code+1, |
894 | blcodes: max_blindex+1); |
895 | compress_block(s, ltree: (ct_data *)s->dyn_ltree, dtree: (ct_data *)s->dyn_dtree); |
896 | s->compressed_len += 3 + s->opt_len; |
897 | } |
898 | Assert (s->compressed_len == s->bits_sent, "bad compressed size" ); |
899 | init_block(s); |
900 | |
901 | if (eof) { |
902 | bi_windup(s); |
903 | s->compressed_len += 7; /* align on byte boundary */ |
904 | } |
905 | Tracev((stderr,"\ncomprlen %lu(%lu) " , s->compressed_len>>3, |
906 | s->compressed_len-7*eof)); |
907 | |
908 | return s->compressed_len >> 3; |
909 | } |
910 | |
911 | /* =========================================================================== |
912 | * Save the match info and tally the frequency counts. Return true if |
913 | * the current block must be flushed. |
914 | */ |
915 | int zlib_tr_tally( |
916 | deflate_state *s, |
917 | unsigned dist, /* distance of matched string */ |
918 | unsigned lc /* match length-MIN_MATCH or unmatched char (if dist==0) */ |
919 | ) |
920 | { |
921 | s->d_buf[s->last_lit] = (ush)dist; |
922 | s->l_buf[s->last_lit++] = (uch)lc; |
923 | if (dist == 0) { |
924 | /* lc is the unmatched char */ |
925 | s->dyn_ltree[lc].Freq++; |
926 | } else { |
927 | s->matches++; |
928 | /* Here, lc is the match length - MIN_MATCH */ |
929 | dist--; /* dist = match distance - 1 */ |
930 | Assert((ush)dist < (ush)MAX_DIST(s) && |
931 | (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && |
932 | (ush)d_code(dist) < (ush)D_CODES, "zlib_tr_tally: bad match" ); |
933 | |
934 | s->dyn_ltree[length_code[lc]+LITERALS+1].Freq++; |
935 | s->dyn_dtree[d_code(dist)].Freq++; |
936 | } |
937 | |
938 | /* Try to guess if it is profitable to stop the current block here */ |
939 | if ((s->last_lit & 0xfff) == 0 && s->level > 2) { |
940 | /* Compute an upper bound for the compressed length */ |
941 | ulg out_length = (ulg)s->last_lit*8L; |
942 | ulg in_length = (ulg)((long)s->strstart - s->block_start); |
943 | int dcode; |
944 | for (dcode = 0; dcode < D_CODES; dcode++) { |
945 | out_length += (ulg)s->dyn_dtree[dcode].Freq * |
946 | (5L+extra_dbits[dcode]); |
947 | } |
948 | out_length >>= 3; |
949 | Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) " , |
950 | s->last_lit, in_length, out_length, |
951 | 100L - out_length*100L/in_length)); |
952 | if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1; |
953 | } |
954 | return (s->last_lit == s->lit_bufsize-1); |
955 | /* We avoid equality with lit_bufsize because of wraparound at 64K |
956 | * on 16 bit machines and because stored blocks are restricted to |
957 | * 64K-1 bytes. |
958 | */ |
959 | } |
960 | |
961 | /* =========================================================================== |
962 | * Send the block data compressed using the given Huffman trees |
963 | */ |
964 | static void compress_block( |
965 | deflate_state *s, |
966 | ct_data *ltree, /* literal tree */ |
967 | ct_data *dtree /* distance tree */ |
968 | ) |
969 | { |
970 | unsigned dist; /* distance of matched string */ |
971 | int lc; /* match length or unmatched char (if dist == 0) */ |
972 | unsigned lx = 0; /* running index in l_buf */ |
973 | unsigned code; /* the code to send */ |
974 | int ; /* number of extra bits to send */ |
975 | |
976 | if (s->last_lit != 0) do { |
977 | dist = s->d_buf[lx]; |
978 | lc = s->l_buf[lx++]; |
979 | if (dist == 0) { |
980 | send_code(s, lc, ltree); /* send a literal byte */ |
981 | Tracecv(isgraph(lc), (stderr," '%c' " , lc)); |
982 | } else { |
983 | /* Here, lc is the match length - MIN_MATCH */ |
984 | code = length_code[lc]; |
985 | send_code(s, code+LITERALS+1, ltree); /* send the length code */ |
986 | extra = extra_lbits[code]; |
987 | if (extra != 0) { |
988 | lc -= base_length[code]; |
989 | send_bits(s, lc, extra); /* send the extra length bits */ |
990 | } |
991 | dist--; /* dist is now the match distance - 1 */ |
992 | code = d_code(dist); |
993 | Assert (code < D_CODES, "bad d_code" ); |
994 | |
995 | send_code(s, code, dtree); /* send the distance code */ |
996 | extra = extra_dbits[code]; |
997 | if (extra != 0) { |
998 | dist -= base_dist[code]; |
999 | send_bits(s, dist, extra); /* send the extra distance bits */ |
1000 | } |
1001 | } /* literal or match pair ? */ |
1002 | |
1003 | /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */ |
1004 | Assert(s->pending < s->lit_bufsize + 2*lx, "pendingBuf overflow" ); |
1005 | |
1006 | } while (lx < s->last_lit); |
1007 | |
1008 | send_code(s, END_BLOCK, ltree); |
1009 | s->last_eob_len = ltree[END_BLOCK].Len; |
1010 | } |
1011 | |
1012 | /* =========================================================================== |
1013 | * Set the data type to ASCII or BINARY, using a crude approximation: |
1014 | * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise. |
1015 | * IN assertion: the fields freq of dyn_ltree are set and the total of all |
1016 | * frequencies does not exceed 64K (to fit in an int on 16 bit machines). |
1017 | */ |
1018 | static void set_data_type( |
1019 | deflate_state *s |
1020 | ) |
1021 | { |
1022 | int n = 0; |
1023 | unsigned ascii_freq = 0; |
1024 | unsigned bin_freq = 0; |
1025 | while (n < 7) bin_freq += s->dyn_ltree[n++].Freq; |
1026 | while (n < 128) ascii_freq += s->dyn_ltree[n++].Freq; |
1027 | while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq; |
1028 | s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? Z_BINARY : Z_ASCII); |
1029 | } |
1030 | |
1031 | /* =========================================================================== |
1032 | * Copy a stored block, storing first the length and its |
1033 | * one's complement if requested. |
1034 | */ |
1035 | static void copy_block( |
1036 | deflate_state *s, |
1037 | char *buf, /* the input data */ |
1038 | unsigned len, /* its length */ |
1039 | int /* true if block header must be written */ |
1040 | ) |
1041 | { |
1042 | bi_windup(s); /* align on byte boundary */ |
1043 | s->last_eob_len = 8; /* enough lookahead for inflate */ |
1044 | |
1045 | if (header) { |
1046 | put_short(s, (ush)len); |
1047 | put_short(s, (ush)~len); |
1048 | #ifdef DEBUG_ZLIB |
1049 | s->bits_sent += 2*16; |
1050 | #endif |
1051 | } |
1052 | #ifdef DEBUG_ZLIB |
1053 | s->bits_sent += (ulg)len<<3; |
1054 | #endif |
1055 | /* bundle up the put_byte(s, *buf++) calls */ |
1056 | memcpy(&s->pending_buf[s->pending], buf, len); |
1057 | s->pending += len; |
1058 | } |
1059 | |
1060 | |