1 /* trees.c -- output deflated data using Huffman coding
2 * Copyright (C) 1995-2012 Jean-loup Gailly
3 * detect_data_type() function provided freely by Cosmin Truta, 2006
4 * For conditions of distribution and use, see copyright notice in zlib.h
10 * The "deflation" process uses several Huffman trees. The more
11 * common source values are represented by shorter bit sequences.
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.
21 * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
22 * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
25 * Data Compression: Methods and Theory, pp. 49-50.
26 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
30 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
35 /* #define GEN_TREES_H */
37 #include "hammer2_zlib_deflate.h"
43 /* ===========================================================================
48 /* Bit length codes must not exceed MAX_BL_BITS bits */
51 /* end of block literal code */
54 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
57 /* repeat a zero length 3-10 times (3 bits of repeat count) */
59 #define REPZ_11_138 18
60 /* repeat a zero length 11-138 times (7 bits of repeat count) */
62 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
63 = {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};
65 local const int extra_dbits[D_CODES] /* extra bits for each distance code */
66 = {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};
68 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
69 = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
71 local const uch bl_order[BL_CODES]
72 = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
73 /* The lengths of the bit length codes are sent in order of decreasing
74 * probability, to avoid transmitting the lengths for unused bit length codes.
77 /* ===========================================================================
78 * Local data. These are initialized only once.
81 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
83 #if defined(GEN_TREES_H) || !defined(STDC)
84 /* non ANSI compilers may not accept trees.h */
86 local ct_data static_ltree[L_CODES+2];
87 /* The static literal tree. Since the bit lengths are imposed, there is no
88 * need for the L_CODES extra codes used during heap construction. However
89 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
93 local ct_data static_dtree[D_CODES];
94 /* The static distance tree. (Actually a trivial tree since all codes use
98 uch _dist_code[DIST_CODE_LEN];
99 /* Distance codes. The first 256 values correspond to the distances
100 * 3 .. 258, the last 256 values correspond to the top 8 bits of
101 * the 15 bit distances.
104 uch _length_code[MAX_MATCH-MIN_MATCH+1];
105 /* length code for each normalized match length (0 == MIN_MATCH) */
107 local int base_length[LENGTH_CODES];
108 /* First normalized length for each code (0 = MIN_MATCH) */
110 local int base_dist[D_CODES];
111 /* First normalized distance for each code (0 = distance of 1) */
114 # include "hammer2_zlib_trees.h"
115 #endif /* GEN_TREES_H */
117 struct static_tree_desc_s {
118 const ct_data *static_tree; /* static tree or NULL */
119 const intf *extra_bits; /* extra bits for each code or NULL */
120 int extra_base; /* base index for extra_bits */
121 int elems; /* max number of elements in the tree */
122 int max_length; /* max bit length for the codes */
125 local static_tree_desc static_l_desc =
126 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
128 local static_tree_desc static_d_desc =
129 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
131 local static_tree_desc static_bl_desc =
132 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
134 /* ===========================================================================
135 * Local (static) routines in this file.
138 local void tr_static_init (void);
139 local void init_block (deflate_state *s);
140 local void pqdownheap (deflate_state *s, ct_data *tree, int k);
141 local void gen_bitlen (deflate_state *s, tree_desc *desc);
142 local void gen_codes (ct_data *tree, int max_code, ushf *bl_count);
143 local void build_tree (deflate_state *s, tree_desc *desc);
144 local void scan_tree (deflate_state *s, ct_data *tree, int max_code);
145 local void send_tree (deflate_state *s, ct_data *tree, int max_code);
146 local int build_bl_tree (deflate_state *s);
147 local void send_all_trees (deflate_state *s, int lcodes, int dcodes,
149 local void compress_block (deflate_state *s, const ct_data *ltree,
150 const ct_data *dtree);
151 local int detect_data_type (deflate_state *s);
152 local unsigned bi_reverse (unsigned value, int length);
153 local void bi_windup (deflate_state *s);
154 local void bi_flush (deflate_state *s);
155 local void copy_block (deflate_state *s, charf *buf, unsigned len,
159 local void gen_trees_header (void);
163 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
164 /* Send a code of the given tree. c and tree must not have side effects */
167 # define send_code(s, c, tree) \
168 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
169 send_bits(s, tree[c].Code, tree[c].Len); }
172 /* ===========================================================================
173 * Output a short LSB first on the stream.
174 * IN assertion: there is enough room in pendingBuf.
176 #define put_short(s, w) { \
177 put_byte(s, (uch)((w) & 0xff)); \
178 put_byte(s, (uch)((ush)(w) >> 8)); \
181 /* ===========================================================================
182 * Send a value on a given number of bits.
183 * IN assertion: length <= 16 and value fits in length bits.
186 local void send_bits (deflate_state *s, int value, int length);
190 send_bits(deflate_state *s, int value, int length)
192 Tracevv((stderr," l %2d v %4x ", length, value));
193 Assert(length > 0 && length <= 15, "invalid length");
194 s->bits_sent += (ulg)length;
196 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
197 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
198 * unused bits in value.
200 if (s->bi_valid > (int)Buf_size - length) {
201 s->bi_buf |= (ush)value << s->bi_valid;
202 put_short(s, s->bi_buf);
203 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
204 s->bi_valid += length - Buf_size;
206 s->bi_buf |= (ush)value << s->bi_valid;
207 s->bi_valid += length;
212 #define send_bits(s, value, length) \
214 if (s->bi_valid > (int)Buf_size - len) {\
216 s->bi_buf |= (ush)val << s->bi_valid;\
217 put_short(s, s->bi_buf);\
218 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
219 s->bi_valid += len - Buf_size;\
221 s->bi_buf |= (ush)(value) << s->bi_valid;\
228 /* the arguments must not have side effects */
230 /* ===========================================================================
231 * Initialize the various 'constant' tables.
237 #if defined(GEN_TREES_H) || !defined(STDC)
238 static int static_init_done = 0;
239 int n; /* iterates over tree elements */
240 int bits; /* bit counter */
241 int length; /* length value */
242 int code; /* code value */
243 int dist; /* distance index */
244 ush bl_count[MAX_BITS+1];
245 /* number of codes at each bit length for an optimal tree */
247 if (static_init_done) return;
249 /* For some embedded targets, global variables are not initialized: */
250 #ifdef NO_INIT_GLOBAL_POINTERS
251 static_l_desc.static_tree = static_ltree;
252 static_l_desc.extra_bits = extra_lbits;
253 static_d_desc.static_tree = static_dtree;
254 static_d_desc.extra_bits = extra_dbits;
255 static_bl_desc.extra_bits = extra_blbits;
258 /* Initialize the mapping length (0..255) -> length code (0..28) */
260 for (code = 0; code < LENGTH_CODES-1; code++) {
261 base_length[code] = length;
262 for (n = 0; n < (1<<extra_lbits[code]); n++) {
263 _length_code[length++] = (uch)code;
266 Assert (length == 256, "tr_static_init: length != 256");
267 /* Note that the length 255 (match length 258) can be represented
268 * in two different ways: code 284 + 5 bits or code 285, so we
269 * overwrite length_code[255] to use the best encoding:
271 _length_code[length-1] = (uch)code;
273 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
275 for (code = 0 ; code < 16; code++) {
276 base_dist[code] = dist;
277 for (n = 0; n < (1<<extra_dbits[code]); n++) {
278 _dist_code[dist++] = (uch)code;
281 Assert (dist == 256, "tr_static_init: dist != 256");
282 dist >>= 7; /* from now on, all distances are divided by 128 */
283 for ( ; code < D_CODES; code++) {
284 base_dist[code] = dist << 7;
285 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
286 _dist_code[256 + dist++] = (uch)code;
289 Assert (dist == 256, "tr_static_init: 256+dist != 512");
291 /* Construct the codes of the static literal tree */
292 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
294 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
295 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
296 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
297 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
298 /* Codes 286 and 287 do not exist, but we must include them in the
299 * tree construction to get a canonical Huffman tree (longest code
302 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
304 /* The static distance tree is trivial: */
305 for (n = 0; n < D_CODES; n++) {
306 static_dtree[n].Len = 5;
307 static_dtree[n].Code = bi_reverse((unsigned)n, 5);
309 static_init_done = 1;
314 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
317 /* ===========================================================================
318 * Genererate the file trees.h describing the static trees.
325 # define SEPARATOR(i, last, width) \
326 ((i) == (last)? "\n};\n\n" : \
327 ((i) % (width) == (width)-1 ? ",\n" : ", "))
332 FILE *header = fopen("trees.h", "w");
335 Assert (header != NULL, "Can't open trees.h");
337 "/* header created automatically with -DGEN_TREES_H */\n\n");
339 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
340 for (i = 0; i < L_CODES+2; i++) {
341 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
342 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
345 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
346 for (i = 0; i < D_CODES; i++) {
347 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
348 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
351 fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
352 for (i = 0; i < DIST_CODE_LEN; i++) {
353 fprintf(header, "%2u%s", _dist_code[i],
354 SEPARATOR(i, DIST_CODE_LEN-1, 20));
358 "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
359 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
360 fprintf(header, "%2u%s", _length_code[i],
361 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
364 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
365 for (i = 0; i < LENGTH_CODES; i++) {
366 fprintf(header, "%1u%s", base_length[i],
367 SEPARATOR(i, LENGTH_CODES-1, 20));
370 fprintf(header, "local const int base_dist[D_CODES] = {\n");
371 for (i = 0; i < D_CODES; i++) {
372 fprintf(header, "%5u%s", base_dist[i],
373 SEPARATOR(i, D_CODES-1, 10));
378 #endif /* GEN_TREES_H */
380 /* ===========================================================================
381 * Initialize the tree data structures for a new zlib stream.
385 _tr_init(deflate_state *s)
389 s->l_desc.dyn_tree = s->dyn_ltree;
390 s->l_desc.stat_desc = &static_l_desc;
392 s->d_desc.dyn_tree = s->dyn_dtree;
393 s->d_desc.stat_desc = &static_d_desc;
395 s->bl_desc.dyn_tree = s->bl_tree;
396 s->bl_desc.stat_desc = &static_bl_desc;
401 s->compressed_len = 0L;
405 /* Initialize the first block of the first file: */
409 /* ===========================================================================
410 * Initialize a new block.
414 init_block(deflate_state *s)
416 int n; /* iterates over tree elements */
418 /* Initialize the trees. */
419 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
420 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
421 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
423 s->dyn_ltree[END_BLOCK].Freq = 1;
424 s->opt_len = s->static_len = 0L;
425 s->last_lit = s->matches = 0;
429 /* Index within the heap array of least frequent node in the Huffman tree */
432 /* ===========================================================================
433 * Remove the smallest element from the heap and recreate the heap with
434 * one less element. Updates heap and heap_len.
436 #define pqremove(s, tree, top) \
438 top = s->heap[SMALLEST]; \
439 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
440 pqdownheap(s, tree, SMALLEST); \
443 /* ===========================================================================
444 * Compares to subtrees, using the tree depth as tie breaker when
445 * the subtrees have equal frequency. This minimizes the worst case length.
447 #define smaller(tree, n, m, depth) \
448 (tree[n].Freq < tree[m].Freq || \
449 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
451 /* ===========================================================================
452 * Restore the heap property by moving down the tree starting at node k,
453 * exchanging a node with the smallest of its two sons if necessary, stopping
454 * when the heap property is re-established (each father smaller than its
459 pqdownheap(deflate_state *s, ct_data *tree, int k) /* the tree to restore, node to move down */
462 int j = k << 1; /* left son of k */
463 while (j <= s->heap_len) {
464 /* Set j to the smallest of the two sons: */
465 if (j < s->heap_len &&
466 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
469 /* Exit if v is smaller than both sons */
470 if (smaller(tree, v, s->heap[j], s->depth)) break;
472 /* Exchange v with the smallest son */
473 s->heap[k] = s->heap[j]; k = j;
475 /* And continue down the tree, setting j to the left son of k */
481 /* ===========================================================================
482 * Compute the optimal bit lengths for a tree and update the total bit length
483 * for the current block.
484 * IN assertion: the fields freq and dad are set, heap[heap_max] and
485 * above are the tree nodes sorted by increasing frequency.
486 * OUT assertions: the field len is set to the optimal bit length, the
487 * array bl_count contains the frequencies for each bit length.
488 * The length opt_len is updated; static_len is also updated if stree is
493 gen_bitlen(deflate_state *s, tree_desc *desc)
495 ct_data *tree = desc->dyn_tree;
496 int max_code = desc->max_code;
497 const ct_data *stree = desc->stat_desc->static_tree;
498 const intf *extra = desc->stat_desc->extra_bits;
499 int base = desc->stat_desc->extra_base;
500 int max_length = desc->stat_desc->max_length;
501 int h; /* heap index */
502 int n, m; /* iterate over the tree elements */
503 int bits; /* bit length */
504 int xbits; /* extra bits */
505 ush f; /* frequency */
506 int overflow = 0; /* number of elements with bit length too large */
508 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
510 /* In a first pass, compute the optimal bit lengths (which may
511 * overflow in the case of the bit length tree).
513 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
515 for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
517 bits = tree[tree[n].Dad].Len + 1;
518 if (bits > max_length) bits = max_length, overflow++;
519 tree[n].Len = (ush)bits;
520 /* We overwrite tree[n].Dad which is no longer needed */
522 if (n > max_code) continue; /* not a leaf node */
526 if (n >= base) xbits = extra[n-base];
528 s->opt_len += (ulg)f * (bits + xbits);
529 if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
531 if (overflow == 0) return;
533 Trace((stderr,"\nbit length overflow\n"));
534 /* This happens for example on obj2 and pic of the Calgary corpus */
536 /* Find the first bit length which could increase: */
539 while (s->bl_count[bits] == 0) bits--;
540 s->bl_count[bits]--; /* move one leaf down the tree */
541 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
542 s->bl_count[max_length]--;
543 /* The brother of the overflow item also moves one step up,
544 * but this does not affect bl_count[max_length]
547 } while (overflow > 0);
549 /* Now recompute all bit lengths, scanning in increasing frequency.
550 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
551 * lengths instead of fixing only the wrong ones. This idea is taken
552 * from 'ar' written by Haruhiko Okumura.)
554 for (bits = max_length; bits != 0; bits--) {
555 n = s->bl_count[bits];
558 if (m > max_code) continue;
559 if ((unsigned) tree[m].Len != (unsigned) bits) {
560 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
561 s->opt_len += ((long)bits - (long)tree[m].Len)
563 tree[m].Len = (ush)bits;
570 /* ===========================================================================
571 * Generate the codes for a given tree and bit counts (which need not be
573 * IN assertion: the array bl_count contains the bit length statistics for
574 * the given tree and the field len is set for all tree elements.
575 * OUT assertion: the field code is set for all tree elements of non
580 gen_codes (ct_data *tree, int max_code, ushf *bl_count)
581 /* the tree to decorate */
582 /* max_code = largest code with non zero frequency */
583 /* *bl_count = number of codes at each bit length */
585 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
586 ush code = 0; /* running code value */
587 int bits; /* bit index */
588 int n; /* code index */
590 /* The distribution counts are first used to generate the code values
591 * without bit reversal.
593 for (bits = 1; bits <= MAX_BITS; bits++) {
594 next_code[bits] = code = (code + bl_count[bits-1]) << 1;
596 /* Check that the bit counts in bl_count are consistent. The last code
599 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
600 "inconsistent bit counts");
601 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
603 for (n = 0; n <= max_code; n++) {
604 int len = tree[n].Len;
605 if (len == 0) continue;
606 /* Now reverse the bits */
607 tree[n].Code = bi_reverse(next_code[len]++, len);
609 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
610 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
614 /* ===========================================================================
615 * Construct one Huffman tree and assigns the code bit strings and lengths.
616 * Update the total bit length for the current block.
617 * IN assertion: the field freq is set for all tree elements.
618 * OUT assertions: the fields len and code are set to the optimal bit length
619 * and corresponding code. The length opt_len is updated; static_len is
620 * also updated if stree is not null. The field max_code is set.
624 build_tree(deflate_state *s, tree_desc *desc) /* the tree descriptor */
626 ct_data *tree = desc->dyn_tree;
627 const ct_data *stree = desc->stat_desc->static_tree;
628 int elems = desc->stat_desc->elems;
629 int n, m; /* iterate over heap elements */
630 int max_code = -1; /* largest code with non zero frequency */
631 int node; /* new node being created */
633 /* Construct the initial heap, with least frequent element in
634 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
635 * heap[0] is not used.
637 s->heap_len = 0, s->heap_max = HEAP_SIZE;
639 for (n = 0; n < elems; n++) {
640 if (tree[n].Freq != 0) {
641 s->heap[++(s->heap_len)] = max_code = n;
648 /* The pkzip format requires that at least one distance code exists,
649 * and that at least one bit should be sent even if there is only one
650 * possible code. So to avoid special checks later on we force at least
651 * two codes of non zero frequency.
653 while (s->heap_len < 2) {
654 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
657 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
658 /* node is 0 or 1 so it does not have extra bits */
660 desc->max_code = max_code;
662 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
663 * establish sub-heaps of increasing lengths:
665 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
667 /* Construct the Huffman tree by repeatedly combining the least two
670 node = elems; /* next internal node of the tree */
672 pqremove(s, tree, n); /* n = node of least frequency */
673 m = s->heap[SMALLEST]; /* m = node of next least frequency */
675 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
676 s->heap[--(s->heap_max)] = m;
678 /* Create a new node father of n and m */
679 tree[node].Freq = tree[n].Freq + tree[m].Freq;
680 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
681 s->depth[n] : s->depth[m]) + 1);
682 tree[n].Dad = tree[m].Dad = (ush)node;
684 if (tree == s->bl_tree) {
685 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
686 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
689 /* and insert the new node in the heap */
690 s->heap[SMALLEST] = node++;
691 pqdownheap(s, tree, SMALLEST);
693 } while (s->heap_len >= 2);
695 s->heap[--(s->heap_max)] = s->heap[SMALLEST];
697 /* At this point, the fields freq and dad are set. We can now
698 * generate the bit lengths.
700 gen_bitlen(s, (tree_desc *)desc);
702 /* The field len is now set, we can generate the bit codes */
703 gen_codes ((ct_data *)tree, max_code, s->bl_count);
706 /* ===========================================================================
707 * Scan a literal or distance tree to determine the frequencies of the codes
708 * in the bit length tree.
712 scan_tree (deflate_state *s, ct_data *tree, int max_code)
713 /* the tree to be scanned */
714 /* and its largest code of non zero frequency */
716 int n; /* iterates over all tree elements */
717 int prevlen = -1; /* last emitted length */
718 int curlen; /* length of current code */
719 int nextlen = tree[0].Len; /* length of next code */
720 int count = 0; /* repeat count of the current code */
721 int max_count = 7; /* max repeat count */
722 int min_count = 4; /* min repeat count */
724 if (nextlen == 0) max_count = 138, min_count = 3;
725 tree[max_code+1].Len = (ush)0xffff; /* guard */
727 for (n = 0; n <= max_code; n++) {
728 curlen = nextlen; nextlen = tree[n+1].Len;
729 if (++count < max_count && curlen == nextlen) {
731 } else if (count < min_count) {
732 s->bl_tree[curlen].Freq += count;
733 } else if (curlen != 0) {
734 if (curlen != prevlen) s->bl_tree[curlen].Freq++;
735 s->bl_tree[REP_3_6].Freq++;
736 } else if (count <= 10) {
737 s->bl_tree[REPZ_3_10].Freq++;
739 s->bl_tree[REPZ_11_138].Freq++;
741 count = 0; prevlen = curlen;
743 max_count = 138, min_count = 3;
744 } else if (curlen == nextlen) {
745 max_count = 6, min_count = 3;
747 max_count = 7, min_count = 4;
752 /* ===========================================================================
753 * Send a literal or distance tree in compressed form, using the codes in
758 send_tree (deflate_state *s, ct_data *tree, int max_code) /* same as above */
760 int n; /* iterates over all tree elements */
761 int prevlen = -1; /* last emitted length */
762 int curlen; /* length of current code */
763 int nextlen = tree[0].Len; /* length of next code */
764 int count = 0; /* repeat count of the current code */
765 int max_count = 7; /* max repeat count */
766 int min_count = 4; /* min repeat count */
768 /* tree[max_code+1].Len = -1; */ /* guard already set */
769 if (nextlen == 0) max_count = 138, min_count = 3;
771 for (n = 0; n <= max_code; n++) {
772 curlen = nextlen; nextlen = tree[n+1].Len;
773 if (++count < max_count && curlen == nextlen) {
775 } else if (count < min_count) {
776 do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
778 } else if (curlen != 0) {
779 if (curlen != prevlen) {
780 send_code(s, curlen, s->bl_tree); count--;
782 Assert(count >= 3 && count <= 6, " 3_6?");
783 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
785 } else if (count <= 10) {
786 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
789 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
791 count = 0; prevlen = curlen;
793 max_count = 138, min_count = 3;
794 } else if (curlen == nextlen) {
795 max_count = 6, min_count = 3;
797 max_count = 7, min_count = 4;
802 /* ===========================================================================
803 * Construct the Huffman tree for the bit lengths and return the index in
804 * bl_order of the last bit length code to send.
808 build_bl_tree(deflate_state *s)
810 int max_blindex; /* index of last bit length code of non zero freq */
812 /* Determine the bit length frequencies for literal and distance trees */
813 scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
814 scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
816 /* Build the bit length tree: */
817 build_tree(s, (tree_desc *)(&(s->bl_desc)));
818 /* opt_len now includes the length of the tree representations, except
819 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
822 /* Determine the number of bit length codes to send. The pkzip format
823 * requires that at least 4 bit length codes be sent. (appnote.txt says
824 * 3 but the actual value used is 4.)
826 for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
827 if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
829 /* Update opt_len to include the bit length tree and counts */
830 s->opt_len += 3*(max_blindex+1) + 5+5+4;
831 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
832 s->opt_len, s->static_len));
837 /* ===========================================================================
838 * Send the header for a block using dynamic Huffman trees: the counts, the
839 * lengths of the bit length codes, the literal tree and the distance tree.
840 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
844 send_all_trees(deflate_state *s, int lcodes, int dcodes, int blcodes)
845 /* number of codes for each tree */
847 int rank; /* index in bl_order */
849 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
850 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
852 Tracev((stderr, "\nbl counts: "));
853 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
854 send_bits(s, dcodes-1, 5);
855 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
856 for (rank = 0; rank < blcodes; rank++) {
857 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
858 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
860 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
862 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
863 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
865 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
866 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
869 /* ===========================================================================
870 * Send a stored block
874 _tr_stored_block(deflate_state *s, charf *buf,
875 ulg stored_len, int last) /* one if this is the last block for a file */
877 send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */
879 s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
880 s->compressed_len += (stored_len + 4) << 3;
882 copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
885 /* ===========================================================================
886 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
890 _tr_flush_bits(deflate_state *s)
895 /* ===========================================================================
896 * Send one empty static block to give enough lookahead for inflate.
897 * This takes 10 bits, of which 7 may remain in the bit buffer.
901 _tr_align(deflate_state *s)
903 send_bits(s, STATIC_TREES<<1, 3);
904 send_code(s, END_BLOCK, static_ltree);
906 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
911 /* ===========================================================================
912 * Determine the best encoding for the current block: dynamic trees, static
913 * trees or store, and output the encoded block to the zip file.
917 _tr_flush_block(deflate_state *s, charf *buf,
918 ulg stored_len, int last)
920 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
921 int max_blindex = 0; /* index of last bit length code of non zero freq */
923 /* Build the Huffman trees unless a stored block is forced */
926 /* Check if the file is binary or text */
927 if (s->strm->data_type == Z_UNKNOWN)
928 s->strm->data_type = detect_data_type(s);
930 /* Construct the literal and distance trees */
931 build_tree(s, (tree_desc *)(&(s->l_desc)));
932 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
935 build_tree(s, (tree_desc *)(&(s->d_desc)));
936 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
938 /* At this point, opt_len and static_len are the total bit lengths of
939 * the compressed block data, excluding the tree representations.
942 /* Build the bit length tree for the above two trees, and get the index
943 * in bl_order of the last bit length code to send.
945 max_blindex = build_bl_tree(s);
947 /* Determine the best encoding. Compute the block lengths in bytes. */
948 opt_lenb = (s->opt_len+3+7)>>3;
949 static_lenb = (s->static_len+3+7)>>3;
951 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
952 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
955 if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
958 Assert(buf != (char*)0, "lost buf");
959 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
963 if (buf != (char*)0) { /* force stored block */
965 if (stored_len+4 <= opt_lenb && buf != (char*)0) {
966 /* 4: two words for the lengths */
968 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
969 * Otherwise we can't have processed more than WSIZE input bytes since
970 * the last block flush, because compression would have been
971 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
972 * transform a block into a stored block.
974 _tr_stored_block(s, buf, stored_len, last);
977 } else if (static_lenb >= 0) { /* force static trees */
979 } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
981 send_bits(s, (STATIC_TREES<<1)+last, 3);
982 compress_block(s, (const ct_data *)static_ltree,
983 (const ct_data *)static_dtree);
985 s->compressed_len += 3 + s->static_len;
988 send_bits(s, (DYN_TREES<<1)+last, 3);
989 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
991 compress_block(s, (const ct_data *)s->dyn_ltree,
992 (const ct_data *)s->dyn_dtree);
994 s->compressed_len += 3 + s->opt_len;
997 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
998 /* The above check is made mod 2^32, for files larger than 512 MB
999 * and uLong implemented on 32 bits.
1006 s->compressed_len += 7; /* align on byte boundary */
1009 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1010 s->compressed_len-7*last));
1013 /* ===========================================================================
1014 * Save the match info and tally the frequency counts. Return true if
1015 * the current block must be flushed.
1019 _tr_tally (deflate_state *s, unsigned dist, unsigned lc)
1021 s->d_buf[s->last_lit] = (ush)dist;
1022 s->l_buf[s->last_lit++] = (uch)lc;
1024 /* lc is the unmatched char */
1025 s->dyn_ltree[lc].Freq++;
1028 /* Here, lc is the match length - MIN_MATCH */
1029 dist--; /* dist = match distance - 1 */
1030 Assert((ush)dist < (ush)MAX_DIST(s) &&
1031 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1032 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1034 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1035 s->dyn_dtree[d_code(dist)].Freq++;
1038 #ifdef TRUNCATE_BLOCK
1039 /* Try to guess if it is profitable to stop the current block here */
1040 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1041 /* Compute an upper bound for the compressed length */
1042 ulg out_length = (ulg)s->last_lit*8L;
1043 ulg in_length = (ulg)((long)s->strstart - s->block_start);
1045 for (dcode = 0; dcode < D_CODES; dcode++) {
1046 out_length += (ulg)s->dyn_dtree[dcode].Freq *
1047 (5L+extra_dbits[dcode]);
1050 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1051 s->last_lit, in_length, out_length,
1052 100L - out_length*100L/in_length));
1053 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1056 return (s->last_lit == s->lit_bufsize-1);
1057 /* We avoid equality with lit_bufsize because of wraparound at 64K
1058 * on 16 bit machines and because stored blocks are restricted to
1063 /* ===========================================================================
1064 * Send the block data compressed using the given Huffman trees
1068 compress_block(deflate_state *s, const ct_data *ltree, const ct_data *dtree)
1070 unsigned dist; /* distance of matched string */
1071 int lc; /* match length or unmatched char (if dist == 0) */
1072 unsigned lx = 0; /* running index in l_buf */
1073 unsigned code; /* the code to send */
1074 int extra; /* number of extra bits to send */
1076 if (s->last_lit != 0) do {
1077 dist = s->d_buf[lx];
1078 lc = s->l_buf[lx++];
1080 send_code(s, lc, ltree); /* send a literal byte */
1081 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1083 /* Here, lc is the match length - MIN_MATCH */
1084 code = _length_code[lc];
1085 send_code(s, code+LITERALS+1, ltree); /* send the length code */
1086 extra = extra_lbits[code];
1088 lc -= base_length[code];
1089 send_bits(s, lc, extra); /* send the extra length bits */
1091 dist--; /* dist is now the match distance - 1 */
1092 code = d_code(dist);
1093 Assert (code < D_CODES, "bad d_code");
1095 send_code(s, code, dtree); /* send the distance code */
1096 extra = extra_dbits[code];
1098 dist -= base_dist[code];
1099 send_bits(s, dist, extra); /* send the extra distance bits */
1101 } /* literal or match pair ? */
1103 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1104 Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1105 "pendingBuf overflow");
1107 } while (lx < s->last_lit);
1109 send_code(s, END_BLOCK, ltree);
1112 /* ===========================================================================
1113 * Check if the data type is TEXT or BINARY, using the following algorithm:
1114 * - TEXT if the two conditions below are satisfied:
1115 * a) There are no non-portable control characters belonging to the
1116 * "black list" (0..6, 14..25, 28..31).
1117 * b) There is at least one printable character belonging to the
1118 * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1119 * - BINARY otherwise.
1120 * - The following partially-portable control characters form a
1121 * "gray list" that is ignored in this detection algorithm:
1122 * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1123 * IN assertion: the fields Freq of dyn_ltree are set.
1127 detect_data_type(deflate_state *s)
1129 /* black_mask is the bit mask of black-listed bytes
1130 * set bits 0..6, 14..25, and 28..31
1131 * 0xf3ffc07f = binary 11110011111111111100000001111111
1133 unsigned long black_mask = 0xf3ffc07fUL;
1136 /* Check for non-textual ("black-listed") bytes. */
1137 for (n = 0; n <= 31; n++, black_mask >>= 1)
1138 if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1141 /* Check for textual ("white-listed") bytes. */
1142 if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1143 || s->dyn_ltree[13].Freq != 0)
1145 for (n = 32; n < LITERALS; n++)
1146 if (s->dyn_ltree[n].Freq != 0)
1149 /* There are no "black-listed" or "white-listed" bytes:
1150 * this stream either is empty or has tolerated ("gray-listed") bytes only.
1155 /* ===========================================================================
1156 * Reverse the first len bits of a code, using straightforward code (a faster
1157 * method would use a table)
1158 * IN assertion: 1 <= len <= 15
1162 bi_reverse(unsigned code, int len)
1164 register unsigned res = 0;
1167 code >>= 1, res <<= 1;
1168 } while (--len > 0);
1172 /* ===========================================================================
1173 * Flush the bit buffer, keeping at most 7 bits in it.
1177 bi_flush(deflate_state *s)
1179 if (s->bi_valid == 16) {
1180 put_short(s, s->bi_buf);
1183 } else if (s->bi_valid >= 8) {
1184 put_byte(s, (Byte)s->bi_buf);
1190 /* ===========================================================================
1191 * Flush the bit buffer and align the output on a byte boundary
1195 bi_windup(deflate_state *s)
1197 if (s->bi_valid > 8) {
1198 put_short(s, s->bi_buf);
1199 } else if (s->bi_valid > 0) {
1200 put_byte(s, (Byte)s->bi_buf);
1205 s->bits_sent = (s->bits_sent+7) & ~7;
1209 /* ===========================================================================
1210 * Copy a stored block, storing first the length and its
1211 * one's complement if requested.
1215 copy_block(deflate_state *s, charf *buf, unsigned len, int header)
1217 bi_windup(s); /* align on byte boundary */
1220 put_short(s, (ush)len);
1221 put_short(s, (ush)~len);
1223 s->bits_sent += 2*16;
1227 s->bits_sent += (ulg)len<<3;
1230 put_byte(s, *buf++);