1 /* trees.c -- output deflated data using Huffman coding
2 * Copyright (C) 1995-2010 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 */
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 #define Buf_size (8 * 2*sizeof(char))
78 /* Number of bits used within bi_buf. (bi_buf might be implemented on
79 * more than 16 bits on some systems.)
82 /* ===========================================================================
83 * Local data. These are initialized only once.
86 #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
88 #if defined(GEN_TREES_H) || !defined(STDC)
89 /* non ANSI compilers may not accept trees.h */
91 local ct_data static_ltree[L_CODES+2];
92 /* The static literal tree. Since the bit lengths are imposed, there is no
93 * need for the L_CODES extra codes used during heap construction. However
94 * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
98 local ct_data static_dtree[D_CODES];
99 /* The static distance tree. (Actually a trivial tree since all codes use
103 uch _dist_code[DIST_CODE_LEN];
104 /* Distance codes. The first 256 values correspond to the distances
105 * 3 .. 258, the last 256 values correspond to the top 8 bits of
106 * the 15 bit distances.
109 uch _length_code[MAX_MATCH-MIN_MATCH+1];
110 /* length code for each normalized match length (0 == MIN_MATCH) */
112 local int base_length[LENGTH_CODES];
113 /* First normalized length for each code (0 = MIN_MATCH) */
115 local int base_dist[D_CODES];
116 /* First normalized distance for each code (0 = distance of 1) */
120 #endif /* GEN_TREES_H */
122 struct static_tree_desc_s {
123 const ct_data *static_tree; /* static tree or NULL */
124 const intf *extra_bits; /* extra bits for each code or NULL */
125 int extra_base; /* base index for extra_bits */
126 int elems; /* max number of elements in the tree */
127 int max_length; /* max bit length for the codes */
130 local static_tree_desc static_l_desc =
131 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
133 local static_tree_desc static_d_desc =
134 {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
136 local static_tree_desc static_bl_desc =
137 {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
139 /* ===========================================================================
140 * Local (static) routines in this file.
143 local void tr_static_init OF((void));
144 local void init_block OF((deflate_state *s));
145 local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
146 local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
147 local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
148 local void build_tree OF((deflate_state *s, tree_desc *desc));
149 local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
150 local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
151 local int build_bl_tree OF((deflate_state *s));
152 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
154 local void compress_block OF((deflate_state *s, ct_data *ltree,
156 local int detect_data_type OF((deflate_state *s));
157 local unsigned bi_reverse OF((unsigned value, int length));
158 local void bi_windup OF((deflate_state *s));
159 local void bi_flush OF((deflate_state *s));
160 local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
164 local void gen_trees_header OF((void));
168 # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
169 /* Send a code of the given tree. c and tree must not have side effects */
172 # define send_code(s, c, tree) \
173 { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
174 send_bits(s, tree[c].Code, tree[c].Len); }
177 /* ===========================================================================
178 * Output a short LSB first on the stream.
179 * IN assertion: there is enough room in pendingBuf.
181 #define put_short(s, w) { \
182 put_byte(s, (uch)((w) & 0xff)); \
183 put_byte(s, (uch)((ush)(w) >> 8)); \
186 /* ===========================================================================
187 * Send a value on a given number of bits.
188 * IN assertion: length <= 16 and value fits in length bits.
191 local void send_bits OF((deflate_state *s, int value, int length));
193 local void send_bits(s, value, length)
195 int value; /* value to send */
196 int length; /* number of bits */
198 Tracevv((stderr," l %2d v %4x ", length, value));
199 Assert(length > 0 && length <= 15, "invalid length");
200 s->bits_sent += (ulg)length;
202 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
203 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
204 * unused bits in value.
206 if (s->bi_valid > (int)Buf_size - length) {
207 s->bi_buf |= (ush)value << s->bi_valid;
208 put_short(s, s->bi_buf);
209 s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
210 s->bi_valid += length - Buf_size;
212 s->bi_buf |= (ush)value << s->bi_valid;
213 s->bi_valid += length;
218 #define send_bits(s, value, length) \
220 if (s->bi_valid > (int)Buf_size - len) {\
222 s->bi_buf |= (ush)val << s->bi_valid;\
223 put_short(s, s->bi_buf);\
224 s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
225 s->bi_valid += len - Buf_size;\
227 s->bi_buf |= (ush)(value) << s->bi_valid;\
234 /* the arguments must not have side effects */
236 /* ===========================================================================
237 * Initialize the various 'constant' tables.
239 local void tr_static_init()
241 #if defined(GEN_TREES_H) || !defined(STDC)
242 static int static_init_done = 0;
243 int n; /* iterates over tree elements */
244 int bits; /* bit counter */
245 int length; /* length value */
246 int code; /* code value */
247 int dist; /* distance index */
248 ush bl_count[MAX_BITS+1];
249 /* number of codes at each bit length for an optimal tree */
251 if (static_init_done) return;
253 /* For some embedded targets, global variables are not initialized: */
254 #ifdef NO_INIT_GLOBAL_POINTERS
255 static_l_desc.static_tree = static_ltree;
256 static_l_desc.extra_bits = extra_lbits;
257 static_d_desc.static_tree = static_dtree;
258 static_d_desc.extra_bits = extra_dbits;
259 static_bl_desc.extra_bits = extra_blbits;
262 /* Initialize the mapping length (0..255) -> length code (0..28) */
264 for (code = 0; code < LENGTH_CODES-1; code++) {
265 base_length[code] = length;
266 for (n = 0; n < (1<<extra_lbits[code]); n++) {
267 _length_code[length++] = (uch)code;
270 Assert (length == 256, "tr_static_init: length != 256");
271 /* Note that the length 255 (match length 258) can be represented
272 * in two different ways: code 284 + 5 bits or code 285, so we
273 * overwrite length_code[255] to use the best encoding:
275 _length_code[length-1] = (uch)code;
277 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
279 for (code = 0 ; code < 16; code++) {
280 base_dist[code] = dist;
281 for (n = 0; n < (1<<extra_dbits[code]); n++) {
282 _dist_code[dist++] = (uch)code;
285 Assert (dist == 256, "tr_static_init: dist != 256");
286 dist >>= 7; /* from now on, all distances are divided by 128 */
287 for ( ; code < D_CODES; code++) {
288 base_dist[code] = dist << 7;
289 for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
290 _dist_code[256 + dist++] = (uch)code;
293 Assert (dist == 256, "tr_static_init: 256+dist != 512");
295 /* Construct the codes of the static literal tree */
296 for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
298 while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
299 while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
300 while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
301 while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
302 /* Codes 286 and 287 do not exist, but we must include them in the
303 * tree construction to get a canonical Huffman tree (longest code
306 gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
308 /* The static distance tree is trivial: */
309 for (n = 0; n < D_CODES; n++) {
310 static_dtree[n].Len = 5;
311 static_dtree[n].Code = bi_reverse((unsigned)n, 5);
313 static_init_done = 1;
318 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
321 /* ===========================================================================
322 * Genererate the file trees.h describing the static trees.
329 # define SEPARATOR(i, last, width) \
330 ((i) == (last)? "\n};\n\n" : \
331 ((i) % (width) == (width)-1 ? ",\n" : ", "))
333 void gen_trees_header()
335 FILE *header = fopen("trees.h", "w");
338 Assert (header != NULL, "Can't open trees.h");
340 "/* header created automatically with -DGEN_TREES_H */\n\n");
342 fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
343 for (i = 0; i < L_CODES+2; i++) {
344 fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
345 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
348 fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
349 for (i = 0; i < D_CODES; i++) {
350 fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
351 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
354 fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
355 for (i = 0; i < DIST_CODE_LEN; i++) {
356 fprintf(header, "%2u%s", _dist_code[i],
357 SEPARATOR(i, DIST_CODE_LEN-1, 20));
361 "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
362 for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
363 fprintf(header, "%2u%s", _length_code[i],
364 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
367 fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
368 for (i = 0; i < LENGTH_CODES; i++) {
369 fprintf(header, "%1u%s", base_length[i],
370 SEPARATOR(i, LENGTH_CODES-1, 20));
373 fprintf(header, "local const int base_dist[D_CODES] = {\n");
374 for (i = 0; i < D_CODES; i++) {
375 fprintf(header, "%5u%s", base_dist[i],
376 SEPARATOR(i, D_CODES-1, 10));
381 #endif /* GEN_TREES_H */
383 /* ===========================================================================
384 * Initialize the tree data structures for a new zlib stream.
386 void ZLIB_INTERNAL _tr_init(s)
391 s->l_desc.dyn_tree = s->dyn_ltree;
392 s->l_desc.stat_desc = &static_l_desc;
394 s->d_desc.dyn_tree = s->dyn_dtree;
395 s->d_desc.stat_desc = &static_d_desc;
397 s->bl_desc.dyn_tree = s->bl_tree;
398 s->bl_desc.stat_desc = &static_bl_desc;
402 s->last_eob_len = 8; /* enough lookahead for inflate */
404 s->compressed_len = 0L;
408 /* Initialize the first block of the first file: */
412 /* ===========================================================================
413 * Initialize a new block.
415 local void init_block(s)
418 int n; /* iterates over tree elements */
420 /* Initialize the trees. */
421 for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
422 for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
423 for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
425 s->dyn_ltree[END_BLOCK].Freq = 1;
426 s->opt_len = s->static_len = 0L;
427 s->last_lit = s->matches = 0;
431 /* Index within the heap array of least frequent node in the Huffman tree */
434 /* ===========================================================================
435 * Remove the smallest element from the heap and recreate the heap with
436 * one less element. Updates heap and heap_len.
438 #define pqremove(s, tree, top) \
440 top = s->heap[SMALLEST]; \
441 s->heap[SMALLEST] = s->heap[s->heap_len--]; \
442 pqdownheap(s, tree, SMALLEST); \
445 /* ===========================================================================
446 * Compares to subtrees, using the tree depth as tie breaker when
447 * the subtrees have equal frequency. This minimizes the worst case length.
449 #define smaller(tree, n, m, depth) \
450 (tree[n].Freq < tree[m].Freq || \
451 (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
453 /* ===========================================================================
454 * Restore the heap property by moving down the tree starting at node k,
455 * exchanging a node with the smallest of its two sons if necessary, stopping
456 * when the heap property is re-established (each father smaller than its
459 local void pqdownheap(s, tree, k)
461 ct_data *tree; /* the tree to restore */
462 int k; /* node to move down */
465 int j = k << 1; /* left son of k */
466 while (j <= s->heap_len) {
467 /* Set j to the smallest of the two sons: */
468 if (j < s->heap_len &&
469 smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
472 /* Exit if v is smaller than both sons */
473 if (smaller(tree, v, s->heap[j], s->depth)) break;
475 /* Exchange v with the smallest son */
476 s->heap[k] = s->heap[j]; k = j;
478 /* And continue down the tree, setting j to the left son of k */
484 /* ===========================================================================
485 * Compute the optimal bit lengths for a tree and update the total bit length
486 * for the current block.
487 * IN assertion: the fields freq and dad are set, heap[heap_max] and
488 * above are the tree nodes sorted by increasing frequency.
489 * OUT assertions: the field len is set to the optimal bit length, the
490 * array bl_count contains the frequencies for each bit length.
491 * The length opt_len is updated; static_len is also updated if stree is
494 local void gen_bitlen(s, desc)
496 tree_desc *desc; /* the tree descriptor */
498 ct_data *tree = desc->dyn_tree;
499 int max_code = desc->max_code;
500 const ct_data *stree = desc->stat_desc->static_tree;
501 const intf *extra = desc->stat_desc->extra_bits;
502 int base = desc->stat_desc->extra_base;
503 int max_length = desc->stat_desc->max_length;
504 int h; /* heap index */
505 int n, m; /* iterate over the tree elements */
506 int bits; /* bit length */
507 int xbits; /* extra bits */
508 ush f; /* frequency */
509 int overflow = 0; /* number of elements with bit length too large */
511 for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
513 /* In a first pass, compute the optimal bit lengths (which may
514 * overflow in the case of the bit length tree).
516 tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
518 for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
520 bits = tree[tree[n].Dad].Len + 1;
521 if (bits > max_length) bits = max_length, overflow++;
522 tree[n].Len = (ush)bits;
523 /* We overwrite tree[n].Dad which is no longer needed */
525 if (n > max_code) continue; /* not a leaf node */
529 if (n >= base) xbits = extra[n-base];
531 s->opt_len += (ulg)f * (bits + xbits);
532 if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
534 if (overflow == 0) return;
536 Trace((stderr,"\nbit length overflow\n"));
537 /* This happens for example on obj2 and pic of the Calgary corpus */
539 /* Find the first bit length which could increase: */
542 while (s->bl_count[bits] == 0) bits--;
543 s->bl_count[bits]--; /* move one leaf down the tree */
544 s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
545 s->bl_count[max_length]--;
546 /* The brother of the overflow item also moves one step up,
547 * but this does not affect bl_count[max_length]
550 } while (overflow > 0);
552 /* Now recompute all bit lengths, scanning in increasing frequency.
553 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
554 * lengths instead of fixing only the wrong ones. This idea is taken
555 * from 'ar' written by Haruhiko Okumura.)
557 for (bits = max_length; bits != 0; bits--) {
558 n = s->bl_count[bits];
561 if (m > max_code) continue;
562 if ((unsigned) tree[m].Len != (unsigned) bits) {
563 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
564 s->opt_len += ((long)bits - (long)tree[m].Len)
566 tree[m].Len = (ush)bits;
573 /* ===========================================================================
574 * Generate the codes for a given tree and bit counts (which need not be
576 * IN assertion: the array bl_count contains the bit length statistics for
577 * the given tree and the field len is set for all tree elements.
578 * OUT assertion: the field code is set for all tree elements of non
581 local void gen_codes (tree, max_code, bl_count)
582 ct_data *tree; /* the tree to decorate */
583 int max_code; /* largest code with non zero frequency */
584 ushf *bl_count; /* number of codes at each bit length */
586 ush next_code[MAX_BITS+1]; /* next code value for each bit length */
587 ush code = 0; /* running code value */
588 int bits; /* bit index */
589 int n; /* code index */
591 /* The distribution counts are first used to generate the code values
592 * without bit reversal.
594 for (bits = 1; bits <= MAX_BITS; bits++) {
595 next_code[bits] = code = (code + bl_count[bits-1]) << 1;
597 /* Check that the bit counts in bl_count are consistent. The last code
600 Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
601 "inconsistent bit counts");
602 Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
604 for (n = 0; n <= max_code; n++) {
605 int len = tree[n].Len;
606 if (len == 0) continue;
607 /* Now reverse the bits */
608 tree[n].Code = bi_reverse(next_code[len]++, len);
610 Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
611 n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
615 /* ===========================================================================
616 * Construct one Huffman tree and assigns the code bit strings and lengths.
617 * Update the total bit length for the current block.
618 * IN assertion: the field freq is set for all tree elements.
619 * OUT assertions: the fields len and code are set to the optimal bit length
620 * and corresponding code. The length opt_len is updated; static_len is
621 * also updated if stree is not null. The field max_code is set.
623 local void build_tree(s, desc)
625 tree_desc *desc; /* the tree descriptor */
627 ct_data *tree = desc->dyn_tree;
628 const ct_data *stree = desc->stat_desc->static_tree;
629 int elems = desc->stat_desc->elems;
630 int n, m; /* iterate over heap elements */
631 int max_code = -1; /* largest code with non zero frequency */
632 int node; /* new node being created */
634 /* Construct the initial heap, with least frequent element in
635 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
636 * heap[0] is not used.
638 s->heap_len = 0, s->heap_max = HEAP_SIZE;
640 for (n = 0; n < elems; n++) {
641 if (tree[n].Freq != 0) {
642 s->heap[++(s->heap_len)] = max_code = n;
649 /* The pkzip format requires that at least one distance code exists,
650 * and that at least one bit should be sent even if there is only one
651 * possible code. So to avoid special checks later on we force at least
652 * two codes of non zero frequency.
654 while (s->heap_len < 2) {
655 node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
658 s->opt_len--; if (stree) s->static_len -= stree[node].Len;
659 /* node is 0 or 1 so it does not have extra bits */
661 desc->max_code = max_code;
663 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
664 * establish sub-heaps of increasing lengths:
666 for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
668 /* Construct the Huffman tree by repeatedly combining the least two
671 node = elems; /* next internal node of the tree */
673 pqremove(s, tree, n); /* n = node of least frequency */
674 m = s->heap[SMALLEST]; /* m = node of next least frequency */
676 s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
677 s->heap[--(s->heap_max)] = m;
679 /* Create a new node father of n and m */
680 tree[node].Freq = tree[n].Freq + tree[m].Freq;
681 s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
682 s->depth[n] : s->depth[m]) + 1);
683 tree[n].Dad = tree[m].Dad = (ush)node;
685 if (tree == s->bl_tree) {
686 fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
687 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
690 /* and insert the new node in the heap */
691 s->heap[SMALLEST] = node++;
692 pqdownheap(s, tree, SMALLEST);
694 } while (s->heap_len >= 2);
696 s->heap[--(s->heap_max)] = s->heap[SMALLEST];
698 /* At this point, the fields freq and dad are set. We can now
699 * generate the bit lengths.
701 gen_bitlen(s, (tree_desc *)desc);
703 /* The field len is now set, we can generate the bit codes */
704 gen_codes ((ct_data *)tree, max_code, s->bl_count);
707 /* ===========================================================================
708 * Scan a literal or distance tree to determine the frequencies of the codes
709 * in the bit length tree.
711 local void scan_tree (s, tree, max_code)
713 ct_data *tree; /* the tree to be scanned */
714 int max_code; /* 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
756 local void send_tree (s, tree, max_code)
758 ct_data *tree; /* the tree to be scanned */
759 int max_code; /* and its largest code of non zero frequency */
761 int n; /* iterates over all tree elements */
762 int prevlen = -1; /* last emitted length */
763 int curlen; /* length of current code */
764 int nextlen = tree[0].Len; /* length of next code */
765 int count = 0; /* repeat count of the current code */
766 int max_count = 7; /* max repeat count */
767 int min_count = 4; /* min repeat count */
769 /* tree[max_code+1].Len = -1; */ /* guard already set */
770 if (nextlen == 0) max_count = 138, min_count = 3;
772 for (n = 0; n <= max_code; n++) {
773 curlen = nextlen; nextlen = tree[n+1].Len;
774 if (++count < max_count && curlen == nextlen) {
776 } else if (count < min_count) {
777 do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
779 } else if (curlen != 0) {
780 if (curlen != prevlen) {
781 send_code(s, curlen, s->bl_tree); count--;
783 Assert(count >= 3 && count <= 6, " 3_6?");
784 send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
786 } else if (count <= 10) {
787 send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
790 send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
792 count = 0; prevlen = curlen;
794 max_count = 138, min_count = 3;
795 } else if (curlen == nextlen) {
796 max_count = 6, min_count = 3;
798 max_count = 7, min_count = 4;
803 /* ===========================================================================
804 * Construct the Huffman tree for the bit lengths and return the index in
805 * bl_order of the last bit length code to send.
807 local int build_bl_tree(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.
842 local void send_all_trees(s, lcodes, dcodes, blcodes)
844 int lcodes, dcodes, blcodes; /* number of codes for each tree */
846 int rank; /* index in bl_order */
848 Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
849 Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
851 Tracev((stderr, "\nbl counts: "));
852 send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
853 send_bits(s, dcodes-1, 5);
854 send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
855 for (rank = 0; rank < blcodes; rank++) {
856 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
857 send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
859 Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
861 send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
862 Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
864 send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
865 Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
868 /* ===========================================================================
869 * Send a stored block
871 void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
873 charf *buf; /* input block */
874 ulg stored_len; /* length of input block */
875 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 * Send one empty static block to give enough lookahead for inflate.
887 * This takes 10 bits, of which 7 may remain in the bit buffer.
888 * The current inflate code requires 9 bits of lookahead. If the
889 * last two codes for the previous block (real code plus EOB) were coded
890 * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
891 * the last real code. In this case we send two empty static blocks instead
892 * of one. (There are no problems if the previous block is stored or fixed.)
893 * To simplify the code, we assume the worst case of last real code encoded
896 void ZLIB_INTERNAL _tr_align(s)
899 send_bits(s, STATIC_TREES<<1, 3);
900 send_code(s, END_BLOCK, static_ltree);
902 s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
905 /* Of the 10 bits for the empty block, we have already sent
906 * (10 - bi_valid) bits. The lookahead for the last real code (before
907 * the EOB of the previous block) was thus at least one plus the length
908 * of the EOB plus what we have just sent of the empty static block.
910 if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
911 send_bits(s, STATIC_TREES<<1, 3);
912 send_code(s, END_BLOCK, static_ltree);
914 s->compressed_len += 10L;
921 /* ===========================================================================
922 * Determine the best encoding for the current block: dynamic trees, static
923 * trees or store, and output the encoded block to the zip file.
925 void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
927 charf *buf; /* input block, or NULL if too old */
928 ulg stored_len; /* length of input block */
929 int last; /* one if this is the last block for a file */
931 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
932 int max_blindex = 0; /* index of last bit length code of non zero freq */
934 /* Build the Huffman trees unless a stored block is forced */
937 /* Check if the file is binary or text */
938 if (s->strm->data_type == Z_UNKNOWN)
939 s->strm->data_type = detect_data_type(s);
941 /* Construct the literal and distance trees */
942 build_tree(s, (tree_desc *)(&(s->l_desc)));
943 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
946 build_tree(s, (tree_desc *)(&(s->d_desc)));
947 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
949 /* At this point, opt_len and static_len are the total bit lengths of
950 * the compressed block data, excluding the tree representations.
953 /* Build the bit length tree for the above two trees, and get the index
954 * in bl_order of the last bit length code to send.
956 max_blindex = build_bl_tree(s);
958 /* Determine the best encoding. Compute the block lengths in bytes. */
959 opt_lenb = (s->opt_len+3+7)>>3;
960 static_lenb = (s->static_len+3+7)>>3;
962 Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
963 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
966 if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
969 Assert(buf != (char*)0, "lost buf");
970 opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
974 if (buf != (char*)0) { /* force stored block */
976 if (stored_len+4 <= opt_lenb && buf != (char*)0) {
977 /* 4: two words for the lengths */
979 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
980 * Otherwise we can't have processed more than WSIZE input bytes since
981 * the last block flush, because compression would have been
982 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
983 * transform a block into a stored block.
985 _tr_stored_block(s, buf, stored_len, last);
988 } else if (static_lenb >= 0) { /* force static trees */
990 } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
992 send_bits(s, (STATIC_TREES<<1)+last, 3);
993 compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
995 s->compressed_len += 3 + s->static_len;
998 send_bits(s, (DYN_TREES<<1)+last, 3);
999 send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
1001 compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
1003 s->compressed_len += 3 + s->opt_len;
1006 Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1007 /* The above check is made mod 2^32, for files larger than 512 MB
1008 * and uLong implemented on 32 bits.
1015 s->compressed_len += 7; /* align on byte boundary */
1018 Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1019 s->compressed_len-7*last));
1022 /* ===========================================================================
1023 * Save the match info and tally the frequency counts. Return true if
1024 * the current block must be flushed.
1026 int ZLIB_INTERNAL _tr_tally (s, dist, lc)
1028 unsigned dist; /* distance of matched string */
1029 unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1031 s->d_buf[s->last_lit] = (ush)dist;
1032 s->l_buf[s->last_lit++] = (uch)lc;
1034 /* lc is the unmatched char */
1035 s->dyn_ltree[lc].Freq++;
1038 /* Here, lc is the match length - MIN_MATCH */
1039 dist--; /* dist = match distance - 1 */
1040 Assert((ush)dist < (ush)MAX_DIST(s) &&
1041 (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1042 (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1044 s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1045 s->dyn_dtree[d_code(dist)].Freq++;
1048 #ifdef TRUNCATE_BLOCK
1049 /* Try to guess if it is profitable to stop the current block here */
1050 if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1051 /* Compute an upper bound for the compressed length */
1052 ulg out_length = (ulg)s->last_lit*8L;
1053 ulg in_length = (ulg)((long)s->strstart - s->block_start);
1055 for (dcode = 0; dcode < D_CODES; dcode++) {
1056 out_length += (ulg)s->dyn_dtree[dcode].Freq *
1057 (5L+extra_dbits[dcode]);
1060 Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1061 s->last_lit, in_length, out_length,
1062 100L - out_length*100L/in_length));
1063 if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1066 return (s->last_lit == s->lit_bufsize-1);
1067 /* We avoid equality with lit_bufsize because of wraparound at 64K
1068 * on 16 bit machines and because stored blocks are restricted to
1073 /* ===========================================================================
1074 * Send the block data compressed using the given Huffman trees
1076 local void compress_block(s, ltree, dtree)
1078 ct_data *ltree; /* literal tree */
1079 ct_data *dtree; /* distance tree */
1081 unsigned dist; /* distance of matched string */
1082 int lc; /* match length or unmatched char (if dist == 0) */
1083 unsigned lx = 0; /* running index in l_buf */
1084 unsigned code; /* the code to send */
1085 int extra; /* number of extra bits to send */
1087 if (s->last_lit != 0) do {
1088 dist = s->d_buf[lx];
1089 lc = s->l_buf[lx++];
1091 send_code(s, lc, ltree); /* send a literal byte */
1092 Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1094 /* Here, lc is the match length - MIN_MATCH */
1095 code = _length_code[lc];
1096 send_code(s, code+LITERALS+1, ltree); /* send the length code */
1097 extra = extra_lbits[code];
1099 lc -= base_length[code];
1100 send_bits(s, lc, extra); /* send the extra length bits */
1102 dist--; /* dist is now the match distance - 1 */
1103 code = d_code(dist);
1104 Assert (code < D_CODES, "bad d_code");
1106 send_code(s, code, dtree); /* send the distance code */
1107 extra = extra_dbits[code];
1109 dist -= base_dist[code];
1110 send_bits(s, dist, extra); /* send the extra distance bits */
1112 } /* literal or match pair ? */
1114 /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1115 Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1116 "pendingBuf overflow");
1118 } while (lx < s->last_lit);
1120 send_code(s, END_BLOCK, ltree);
1121 s->last_eob_len = ltree[END_BLOCK].Len;
1124 /* ===========================================================================
1125 * Check if the data type is TEXT or BINARY, using the following algorithm:
1126 * - TEXT if the two conditions below are satisfied:
1127 * a) There are no non-portable control characters belonging to the
1128 * "black list" (0..6, 14..25, 28..31).
1129 * b) There is at least one printable character belonging to the
1130 * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
1131 * - BINARY otherwise.
1132 * - The following partially-portable control characters form a
1133 * "gray list" that is ignored in this detection algorithm:
1134 * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
1135 * IN assertion: the fields Freq of dyn_ltree are set.
1137 local int detect_data_type(s)
1140 /* black_mask is the bit mask of black-listed bytes
1141 * set bits 0..6, 14..25, and 28..31
1142 * 0xf3ffc07f = binary 11110011111111111100000001111111
1144 unsigned long black_mask = 0xf3ffc07fUL;
1147 /* Check for non-textual ("black-listed") bytes. */
1148 for (n = 0; n <= 31; n++, black_mask >>= 1)
1149 if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
1152 /* Check for textual ("white-listed") bytes. */
1153 if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
1154 || s->dyn_ltree[13].Freq != 0)
1156 for (n = 32; n < LITERALS; n++)
1157 if (s->dyn_ltree[n].Freq != 0)
1160 /* There are no "black-listed" or "white-listed" bytes:
1161 * this stream either is empty or has tolerated ("gray-listed") bytes only.
1166 /* ===========================================================================
1167 * Reverse the first len bits of a code, using straightforward code (a faster
1168 * method would use a table)
1169 * IN assertion: 1 <= len <= 15
1171 local unsigned bi_reverse(code, len)
1172 unsigned code; /* the value to invert */
1173 int len; /* its bit length */
1175 register unsigned res = 0;
1178 code >>= 1, res <<= 1;
1179 } while (--len > 0);
1183 /* ===========================================================================
1184 * Flush the bit buffer, keeping at most 7 bits in it.
1186 local void bi_flush(s)
1189 if (s->bi_valid == 16) {
1190 put_short(s, s->bi_buf);
1193 } else if (s->bi_valid >= 8) {
1194 put_byte(s, (Byte)s->bi_buf);
1200 /* ===========================================================================
1201 * Flush the bit buffer and align the output on a byte boundary
1203 local void bi_windup(s)
1206 if (s->bi_valid > 8) {
1207 put_short(s, s->bi_buf);
1208 } else if (s->bi_valid > 0) {
1209 put_byte(s, (Byte)s->bi_buf);
1214 s->bits_sent = (s->bits_sent+7) & ~7;
1218 /* ===========================================================================
1219 * Copy a stored block, storing first the length and its
1220 * one's complement if requested.
1222 local void copy_block(s, buf, len, header)
1224 charf *buf; /* the input data */
1225 unsigned len; /* its length */
1226 int header; /* true if block header must be written */
1228 bi_windup(s); /* align on byte boundary */
1229 s->last_eob_len = 8; /* enough lookahead for inflate */
1232 put_short(s, (ush)len);
1233 put_short(s, (ush)~len);
1235 s->bits_sent += 2*16;
1239 s->bits_sent += (ulg)len<<3;
1242 put_byte(s, *buf++);