1: /* trees.c -- output deflated data using Huffman coding
2: * Copyright (C) 1995-2005 Jean-loup Gailly
3: * For conditions of distribution and use, see copyright notice in zlib.h
4: */
5:
6: /*
7: * ALGORITHM
8: *
9: * The "deflation" process uses several Huffman trees. The more
10: * common source values are represented by shorter bit sequences.
11: *
12: * Each code tree is stored in a compressed form which is itself
13: * a Huffman encoding of the lengths of all the code strings (in
14: * ascending order by source values). The actual code strings are
15: * reconstructed from the lengths in the inflate process, as described
16: * in the deflate specification.
17: *
18: * REFERENCES
19: *
20: * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
21: * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
22: *
23: * Storer, James A.
24: * Data Compression: Methods and Theory, pp. 49-50.
25: * Computer Science Press, 1988. ISBN 0-7167-8156-5.
26: *
27: * Sedgewick, R.
28: * Algorithms, p290.
29: * Addison-Wesley, 1983. ISBN 0-201-06672-6.
30: */
31:
32: /* @(#) $Id: trees.c,v 1.1.1.1 2012/02/17 15:09:30 misho Exp $ */
33:
34: /* #define GEN_TREES_H */
35:
36: #include "deflate.h"
37:
38: #ifdef DEBUG
39: # include <ctype.h>
40: #endif
41:
42: /* ===========================================================================
43: * Constants
44: */
45:
46: #define MAX_BL_BITS 7
47: /* Bit length codes must not exceed MAX_BL_BITS bits */
48:
49: #define END_BLOCK 256
50: /* end of block literal code */
51:
52: #define REP_3_6 16
53: /* repeat previous bit length 3-6 times (2 bits of repeat count) */
54:
55: #define REPZ_3_10 17
56: /* repeat a zero length 3-10 times (3 bits of repeat count) */
57:
58: #define REPZ_11_138 18
59: /* repeat a zero length 11-138 times (7 bits of repeat count) */
60:
61: local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
62: = {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};
63:
64: local const int extra_dbits[D_CODES] /* extra bits for each distance code */
65: = {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};
66:
67: local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
68: = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
69:
70: local const uch bl_order[BL_CODES]
71: = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
72: /* The lengths of the bit length codes are sent in order of decreasing
73: * probability, to avoid transmitting the lengths for unused bit length codes.
74: */
75:
76: #define Buf_size (8 * 2*sizeof(char))
77: /* Number of bits used within bi_buf. (bi_buf might be implemented on
78: * more than 16 bits on some systems.)
79: */
80:
81: /* ===========================================================================
82: * Local data. These are initialized only once.
83: */
84:
85: #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
86:
87: #if defined(GEN_TREES_H) || !defined(STDC)
88: /* non ANSI compilers may not accept trees.h */
89:
90: local ct_data static_ltree[L_CODES+2];
91: /* The static literal tree. Since the bit lengths are imposed, there is no
92: * need for the L_CODES extra codes used during heap construction. However
93: * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
94: * below).
95: */
96:
97: local ct_data static_dtree[D_CODES];
98: /* The static distance tree. (Actually a trivial tree since all codes use
99: * 5 bits.)
100: */
101:
102: uch _dist_code[DIST_CODE_LEN];
103: /* Distance codes. The first 256 values correspond to the distances
104: * 3 .. 258, the last 256 values correspond to the top 8 bits of
105: * the 15 bit distances.
106: */
107:
108: uch _length_code[MAX_MATCH-MIN_MATCH+1];
109: /* length code for each normalized match length (0 == MIN_MATCH) */
110:
111: local int base_length[LENGTH_CODES];
112: /* First normalized length for each code (0 = MIN_MATCH) */
113:
114: local int base_dist[D_CODES];
115: /* First normalized distance for each code (0 = distance of 1) */
116:
117: #else
118: # include "trees.h"
119: #endif /* GEN_TREES_H */
120:
121: struct static_tree_desc_s {
122: const ct_data *static_tree; /* static tree or NULL */
123: const intf *extra_bits; /* extra bits for each code or NULL */
124: int extra_base; /* base index for extra_bits */
125: int elems; /* max number of elements in the tree */
126: int max_length; /* max bit length for the codes */
127: };
128:
129: local static_tree_desc static_l_desc =
130: {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
131:
132: local static_tree_desc static_d_desc =
133: {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
134:
135: local static_tree_desc static_bl_desc =
136: {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
137:
138: /* ===========================================================================
139: * Local (static) routines in this file.
140: */
141:
142: local void tr_static_init OF((void));
143: local void init_block OF((deflate_state *s));
144: local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
145: local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
146: local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
147: local void build_tree OF((deflate_state *s, tree_desc *desc));
148: local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
149: local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
150: local int build_bl_tree OF((deflate_state *s));
151: local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
152: int blcodes));
153: local void compress_block OF((deflate_state *s, ct_data *ltree,
154: ct_data *dtree));
155: local void set_data_type OF((deflate_state *s));
156: local unsigned bi_reverse OF((unsigned value, int length));
157: local void bi_windup OF((deflate_state *s));
158: local void bi_flush OF((deflate_state *s));
159: local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
160: int header));
161:
162: #ifdef GEN_TREES_H
163: local void gen_trees_header OF((void));
164: #endif
165:
166: #ifndef DEBUG
167: # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
168: /* Send a code of the given tree. c and tree must not have side effects */
169:
170: #else /* DEBUG */
171: # define send_code(s, c, tree) \
172: { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
173: send_bits(s, tree[c].Code, tree[c].Len); }
174: #endif
175:
176: /* ===========================================================================
177: * Output a short LSB first on the stream.
178: * IN assertion: there is enough room in pendingBuf.
179: */
180: #define put_short(s, w) { \
181: put_byte(s, (uch)((w) & 0xff)); \
182: put_byte(s, (uch)((ush)(w) >> 8)); \
183: }
184:
185: /* ===========================================================================
186: * Send a value on a given number of bits.
187: * IN assertion: length <= 16 and value fits in length bits.
188: */
189: #ifdef DEBUG
190: local void send_bits OF((deflate_state *s, int value, int length));
191:
192: local void send_bits(s, value, length)
193: deflate_state *s;
194: int value; /* value to send */
195: int length; /* number of bits */
196: {
197: Tracevv((stderr," l %2d v %4x ", length, value));
198: Assert(length > 0 && length <= 15, "invalid length");
199: s->bits_sent += (ulg)length;
200:
201: /* If not enough room in bi_buf, use (valid) bits from bi_buf and
202: * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
203: * unused bits in value.
204: */
205: if (s->bi_valid > (int)Buf_size - length) {
206: s->bi_buf |= (value << s->bi_valid);
207: put_short(s, s->bi_buf);
208: s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
209: s->bi_valid += length - Buf_size;
210: } else {
211: s->bi_buf |= value << s->bi_valid;
212: s->bi_valid += length;
213: }
214: }
215: #else /* !DEBUG */
216:
217: #define send_bits(s, value, length) \
218: { int len = length;\
219: if (s->bi_valid > (int)Buf_size - len) {\
220: int val = value;\
221: s->bi_buf |= (val << s->bi_valid);\
222: put_short(s, s->bi_buf);\
223: s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
224: s->bi_valid += len - Buf_size;\
225: } else {\
226: s->bi_buf |= (value) << s->bi_valid;\
227: s->bi_valid += len;\
228: }\
229: }
230: #endif /* DEBUG */
231:
232:
233: /* the arguments must not have side effects */
234:
235: /* ===========================================================================
236: * Initialize the various 'constant' tables.
237: */
238: local void tr_static_init()
239: {
240: #if defined(GEN_TREES_H) || !defined(STDC)
241: static int static_init_done = 0;
242: int n; /* iterates over tree elements */
243: int bits; /* bit counter */
244: int length; /* length value */
245: int code; /* code value */
246: int dist; /* distance index */
247: ush bl_count[MAX_BITS+1];
248: /* number of codes at each bit length for an optimal tree */
249:
250: if (static_init_done) return;
251:
252: /* For some embedded targets, global variables are not initialized: */
253: static_l_desc.static_tree = static_ltree;
254: static_l_desc.extra_bits = extra_lbits;
255: static_d_desc.static_tree = static_dtree;
256: static_d_desc.extra_bits = extra_dbits;
257: static_bl_desc.extra_bits = extra_blbits;
258:
259: /* Initialize the mapping length (0..255) -> length code (0..28) */
260: length = 0;
261: for (code = 0; code < LENGTH_CODES-1; code++) {
262: base_length[code] = length;
263: for (n = 0; n < (1<<extra_lbits[code]); n++) {
264: _length_code[length++] = (uch)code;
265: }
266: }
267: Assert (length == 256, "tr_static_init: length != 256");
268: /* Note that the length 255 (match length 258) can be represented
269: * in two different ways: code 284 + 5 bits or code 285, so we
270: * overwrite length_code[255] to use the best encoding:
271: */
272: _length_code[length-1] = (uch)code;
273:
274: /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
275: dist = 0;
276: for (code = 0 ; code < 16; code++) {
277: base_dist[code] = dist;
278: for (n = 0; n < (1<<extra_dbits[code]); n++) {
279: _dist_code[dist++] = (uch)code;
280: }
281: }
282: Assert (dist == 256, "tr_static_init: dist != 256");
283: dist >>= 7; /* from now on, all distances are divided by 128 */
284: for ( ; code < D_CODES; code++) {
285: base_dist[code] = dist << 7;
286: for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
287: _dist_code[256 + dist++] = (uch)code;
288: }
289: }
290: Assert (dist == 256, "tr_static_init: 256+dist != 512");
291:
292: /* Construct the codes of the static literal tree */
293: for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
294: n = 0;
295: while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
296: while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
297: while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
298: while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
299: /* Codes 286 and 287 do not exist, but we must include them in the
300: * tree construction to get a canonical Huffman tree (longest code
301: * all ones)
302: */
303: gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
304:
305: /* The static distance tree is trivial: */
306: for (n = 0; n < D_CODES; n++) {
307: static_dtree[n].Len = 5;
308: static_dtree[n].Code = bi_reverse((unsigned)n, 5);
309: }
310: static_init_done = 1;
311:
312: # ifdef GEN_TREES_H
313: gen_trees_header();
314: # endif
315: #endif /* defined(GEN_TREES_H) || !defined(STDC) */
316: }
317:
318: /* ===========================================================================
319: * Genererate the file trees.h describing the static trees.
320: */
321: #ifdef GEN_TREES_H
322: # ifndef DEBUG
323: # include <stdio.h>
324: # endif
325:
326: # define SEPARATOR(i, last, width) \
327: ((i) == (last)? "\n};\n\n" : \
328: ((i) % (width) == (width)-1 ? ",\n" : ", "))
329:
330: void gen_trees_header()
331: {
332: FILE *header = fopen("trees.h", "w");
333: int i;
334:
335: Assert (header != NULL, "Can't open trees.h");
336: fprintf(header,
337: "/* header created automatically with -DGEN_TREES_H */\n\n");
338:
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));
343: }
344:
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));
349: }
350:
351: fprintf(header, "const uch _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));
355: }
356:
357: fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
358: for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
359: fprintf(header, "%2u%s", _length_code[i],
360: SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
361: }
362:
363: fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
364: for (i = 0; i < LENGTH_CODES; i++) {
365: fprintf(header, "%1u%s", base_length[i],
366: SEPARATOR(i, LENGTH_CODES-1, 20));
367: }
368:
369: fprintf(header, "local const int base_dist[D_CODES] = {\n");
370: for (i = 0; i < D_CODES; i++) {
371: fprintf(header, "%5u%s", base_dist[i],
372: SEPARATOR(i, D_CODES-1, 10));
373: }
374:
375: fclose(header);
376: }
377: #endif /* GEN_TREES_H */
378:
379: /* ===========================================================================
380: * Initialize the tree data structures for a new zlib stream.
381: */
382: void _tr_init(s)
383: deflate_state *s;
384: {
385: tr_static_init();
386:
387: s->l_desc.dyn_tree = s->dyn_ltree;
388: s->l_desc.stat_desc = &static_l_desc;
389:
390: s->d_desc.dyn_tree = s->dyn_dtree;
391: s->d_desc.stat_desc = &static_d_desc;
392:
393: s->bl_desc.dyn_tree = s->bl_tree;
394: s->bl_desc.stat_desc = &static_bl_desc;
395:
396: s->bi_buf = 0;
397: s->bi_valid = 0;
398: s->last_eob_len = 8; /* enough lookahead for inflate */
399: #ifdef DEBUG
400: s->compressed_len = 0L;
401: s->bits_sent = 0L;
402: #endif
403:
404: /* Initialize the first block of the first file: */
405: init_block(s);
406: }
407:
408: /* ===========================================================================
409: * Initialize a new block.
410: */
411: local void init_block(s)
412: deflate_state *s;
413: {
414: int n; /* iterates over tree elements */
415:
416: /* Initialize the trees. */
417: for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
418: for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
419: for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
420:
421: s->dyn_ltree[END_BLOCK].Freq = 1;
422: s->opt_len = s->static_len = 0L;
423: s->last_lit = s->matches = 0;
424: }
425:
426: #define SMALLEST 1
427: /* Index within the heap array of least frequent node in the Huffman tree */
428:
429:
430: /* ===========================================================================
431: * Remove the smallest element from the heap and recreate the heap with
432: * one less element. Updates heap and heap_len.
433: */
434: #define pqremove(s, tree, top) \
435: {\
436: top = s->heap[SMALLEST]; \
437: s->heap[SMALLEST] = s->heap[s->heap_len--]; \
438: pqdownheap(s, tree, SMALLEST); \
439: }
440:
441: /* ===========================================================================
442: * Compares to subtrees, using the tree depth as tie breaker when
443: * the subtrees have equal frequency. This minimizes the worst case length.
444: */
445: #define smaller(tree, n, m, depth) \
446: (tree[n].Freq < tree[m].Freq || \
447: (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
448:
449: /* ===========================================================================
450: * Restore the heap property by moving down the tree starting at node k,
451: * exchanging a node with the smallest of its two sons if necessary, stopping
452: * when the heap property is re-established (each father smaller than its
453: * two sons).
454: */
455: local void pqdownheap(s, tree, k)
456: deflate_state *s;
457: ct_data *tree; /* the tree to restore */
458: int k; /* node to move down */
459: {
460: int v = s->heap[k];
461: int j = k << 1; /* left son of k */
462: while (j <= s->heap_len) {
463: /* Set j to the smallest of the two sons: */
464: if (j < s->heap_len &&
465: smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
466: j++;
467: }
468: /* Exit if v is smaller than both sons */
469: if (smaller(tree, v, s->heap[j], s->depth)) break;
470:
471: /* Exchange v with the smallest son */
472: s->heap[k] = s->heap[j]; k = j;
473:
474: /* And continue down the tree, setting j to the left son of k */
475: j <<= 1;
476: }
477: s->heap[k] = v;
478: }
479:
480: /* ===========================================================================
481: * Compute the optimal bit lengths for a tree and update the total bit length
482: * for the current block.
483: * IN assertion: the fields freq and dad are set, heap[heap_max] and
484: * above are the tree nodes sorted by increasing frequency.
485: * OUT assertions: the field len is set to the optimal bit length, the
486: * array bl_count contains the frequencies for each bit length.
487: * The length opt_len is updated; static_len is also updated if stree is
488: * not null.
489: */
490: local void gen_bitlen(s, desc)
491: deflate_state *s;
492: tree_desc *desc; /* the tree descriptor */
493: {
494: ct_data *tree = desc->dyn_tree;
495: int max_code = desc->max_code;
496: const ct_data *stree = desc->stat_desc->static_tree;
497: const intf *extra = desc->stat_desc->extra_bits;
498: int base = desc->stat_desc->extra_base;
499: int max_length = desc->stat_desc->max_length;
500: int h; /* heap index */
501: int n, m; /* iterate over the tree elements */
502: int bits; /* bit length */
503: int xbits; /* extra bits */
504: ush f; /* frequency */
505: int overflow = 0; /* number of elements with bit length too large */
506:
507: for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
508:
509: /* In a first pass, compute the optimal bit lengths (which may
510: * overflow in the case of the bit length tree).
511: */
512: tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
513:
514: for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
515: n = s->heap[h];
516: bits = tree[tree[n].Dad].Len + 1;
517: if (bits > max_length) bits = max_length, overflow++;
518: tree[n].Len = (ush)bits;
519: /* We overwrite tree[n].Dad which is no longer needed */
520:
521: if (n > max_code) continue; /* not a leaf node */
522:
523: s->bl_count[bits]++;
524: xbits = 0;
525: if (n >= base) xbits = extra[n-base];
526: f = tree[n].Freq;
527: s->opt_len += (ulg)f * (bits + xbits);
528: if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
529: }
530: if (overflow == 0) return;
531:
532: Trace((stderr,"\nbit length overflow\n"));
533: /* This happens for example on obj2 and pic of the Calgary corpus */
534:
535: /* Find the first bit length which could increase: */
536: do {
537: bits = max_length-1;
538: while (s->bl_count[bits] == 0) bits--;
539: s->bl_count[bits]--; /* move one leaf down the tree */
540: s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
541: s->bl_count[max_length]--;
542: /* The brother of the overflow item also moves one step up,
543: * but this does not affect bl_count[max_length]
544: */
545: overflow -= 2;
546: } while (overflow > 0);
547:
548: /* Now recompute all bit lengths, scanning in increasing frequency.
549: * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
550: * lengths instead of fixing only the wrong ones. This idea is taken
551: * from 'ar' written by Haruhiko Okumura.)
552: */
553: for (bits = max_length; bits != 0; bits--) {
554: n = s->bl_count[bits];
555: while (n != 0) {
556: m = s->heap[--h];
557: if (m > max_code) continue;
558: if ((unsigned) tree[m].Len != (unsigned) bits) {
559: Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
560: s->opt_len += ((long)bits - (long)tree[m].Len)
561: *(long)tree[m].Freq;
562: tree[m].Len = (ush)bits;
563: }
564: n--;
565: }
566: }
567: }
568:
569: /* ===========================================================================
570: * Generate the codes for a given tree and bit counts (which need not be
571: * optimal).
572: * IN assertion: the array bl_count contains the bit length statistics for
573: * the given tree and the field len is set for all tree elements.
574: * OUT assertion: the field code is set for all tree elements of non
575: * zero code length.
576: */
577: local void gen_codes (tree, max_code, bl_count)
578: ct_data *tree; /* the tree to decorate */
579: int max_code; /* largest code with non zero frequency */
580: ushf *bl_count; /* number of codes at each bit length */
581: {
582: ush next_code[MAX_BITS+1]; /* next code value for each bit length */
583: ush code = 0; /* running code value */
584: int bits; /* bit index */
585: int n; /* code index */
586:
587: /* The distribution counts are first used to generate the code values
588: * without bit reversal.
589: */
590: for (bits = 1; bits <= MAX_BITS; bits++) {
591: next_code[bits] = code = (code + bl_count[bits-1]) << 1;
592: }
593: /* Check that the bit counts in bl_count are consistent. The last code
594: * must be all ones.
595: */
596: Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
597: "inconsistent bit counts");
598: Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
599:
600: for (n = 0; n <= max_code; n++) {
601: int len = tree[n].Len;
602: if (len == 0) continue;
603: /* Now reverse the bits */
604: tree[n].Code = bi_reverse(next_code[len]++, len);
605:
606: Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
607: n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
608: }
609: }
610:
611: /* ===========================================================================
612: * Construct one Huffman tree and assigns the code bit strings and lengths.
613: * Update the total bit length for the current block.
614: * IN assertion: the field freq is set for all tree elements.
615: * OUT assertions: the fields len and code are set to the optimal bit length
616: * and corresponding code. The length opt_len is updated; static_len is
617: * also updated if stree is not null. The field max_code is set.
618: */
619: local void build_tree(s, desc)
620: deflate_state *s;
621: tree_desc *desc; /* the tree descriptor */
622: {
623: ct_data *tree = desc->dyn_tree;
624: const ct_data *stree = desc->stat_desc->static_tree;
625: int elems = desc->stat_desc->elems;
626: int n, m; /* iterate over heap elements */
627: int max_code = -1; /* largest code with non zero frequency */
628: int node; /* new node being created */
629:
630: /* Construct the initial heap, with least frequent element in
631: * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
632: * heap[0] is not used.
633: */
634: s->heap_len = 0, s->heap_max = HEAP_SIZE;
635:
636: for (n = 0; n < elems; n++) {
637: if (tree[n].Freq != 0) {
638: s->heap[++(s->heap_len)] = max_code = n;
639: s->depth[n] = 0;
640: } else {
641: tree[n].Len = 0;
642: }
643: }
644:
645: /* The pkzip format requires that at least one distance code exists,
646: * and that at least one bit should be sent even if there is only one
647: * possible code. So to avoid special checks later on we force at least
648: * two codes of non zero frequency.
649: */
650: while (s->heap_len < 2) {
651: node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
652: tree[node].Freq = 1;
653: s->depth[node] = 0;
654: s->opt_len--; if (stree) s->static_len -= stree[node].Len;
655: /* node is 0 or 1 so it does not have extra bits */
656: }
657: desc->max_code = max_code;
658:
659: /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
660: * establish sub-heaps of increasing lengths:
661: */
662: for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
663:
664: /* Construct the Huffman tree by repeatedly combining the least two
665: * frequent nodes.
666: */
667: node = elems; /* next internal node of the tree */
668: do {
669: pqremove(s, tree, n); /* n = node of least frequency */
670: m = s->heap[SMALLEST]; /* m = node of next least frequency */
671:
672: s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
673: s->heap[--(s->heap_max)] = m;
674:
675: /* Create a new node father of n and m */
676: tree[node].Freq = tree[n].Freq + tree[m].Freq;
677: s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
678: s->depth[n] : s->depth[m]) + 1);
679: tree[n].Dad = tree[m].Dad = (ush)node;
680: #ifdef DUMP_BL_TREE
681: if (tree == s->bl_tree) {
682: fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
683: node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
684: }
685: #endif
686: /* and insert the new node in the heap */
687: s->heap[SMALLEST] = node++;
688: pqdownheap(s, tree, SMALLEST);
689:
690: } while (s->heap_len >= 2);
691:
692: s->heap[--(s->heap_max)] = s->heap[SMALLEST];
693:
694: /* At this point, the fields freq and dad are set. We can now
695: * generate the bit lengths.
696: */
697: gen_bitlen(s, (tree_desc *)desc);
698:
699: /* The field len is now set, we can generate the bit codes */
700: gen_codes ((ct_data *)tree, max_code, s->bl_count);
701: }
702:
703: /* ===========================================================================
704: * Scan a literal or distance tree to determine the frequencies of the codes
705: * in the bit length tree.
706: */
707: local void scan_tree (s, tree, max_code)
708: deflate_state *s;
709: ct_data *tree; /* the tree to be scanned */
710: int max_code; /* and its largest code of non zero frequency */
711: {
712: int n; /* iterates over all tree elements */
713: int prevlen = -1; /* last emitted length */
714: int curlen; /* length of current code */
715: int nextlen = tree[0].Len; /* length of next code */
716: int count = 0; /* repeat count of the current code */
717: int max_count = 7; /* max repeat count */
718: int min_count = 4; /* min repeat count */
719:
720: if (nextlen == 0) max_count = 138, min_count = 3;
721: tree[max_code+1].Len = (ush)0xffff; /* guard */
722:
723: for (n = 0; n <= max_code; n++) {
724: curlen = nextlen; nextlen = tree[n+1].Len;
725: if (++count < max_count && curlen == nextlen) {
726: continue;
727: } else if (count < min_count) {
728: s->bl_tree[curlen].Freq += count;
729: } else if (curlen != 0) {
730: if (curlen != prevlen) s->bl_tree[curlen].Freq++;
731: s->bl_tree[REP_3_6].Freq++;
732: } else if (count <= 10) {
733: s->bl_tree[REPZ_3_10].Freq++;
734: } else {
735: s->bl_tree[REPZ_11_138].Freq++;
736: }
737: count = 0; prevlen = curlen;
738: if (nextlen == 0) {
739: max_count = 138, min_count = 3;
740: } else if (curlen == nextlen) {
741: max_count = 6, min_count = 3;
742: } else {
743: max_count = 7, min_count = 4;
744: }
745: }
746: }
747:
748: /* ===========================================================================
749: * Send a literal or distance tree in compressed form, using the codes in
750: * bl_tree.
751: */
752: local void send_tree (s, tree, max_code)
753: deflate_state *s;
754: ct_data *tree; /* the tree to be scanned */
755: int max_code; /* and its largest code of non zero frequency */
756: {
757: int n; /* iterates over all tree elements */
758: int prevlen = -1; /* last emitted length */
759: int curlen; /* length of current code */
760: int nextlen = tree[0].Len; /* length of next code */
761: int count = 0; /* repeat count of the current code */
762: int max_count = 7; /* max repeat count */
763: int min_count = 4; /* min repeat count */
764:
765: /* tree[max_code+1].Len = -1; */ /* guard already set */
766: if (nextlen == 0) max_count = 138, min_count = 3;
767:
768: for (n = 0; n <= max_code; n++) {
769: curlen = nextlen; nextlen = tree[n+1].Len;
770: if (++count < max_count && curlen == nextlen) {
771: continue;
772: } else if (count < min_count) {
773: do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
774:
775: } else if (curlen != 0) {
776: if (curlen != prevlen) {
777: send_code(s, curlen, s->bl_tree); count--;
778: }
779: Assert(count >= 3 && count <= 6, " 3_6?");
780: send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
781:
782: } else if (count <= 10) {
783: send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
784:
785: } else {
786: send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
787: }
788: count = 0; prevlen = curlen;
789: if (nextlen == 0) {
790: max_count = 138, min_count = 3;
791: } else if (curlen == nextlen) {
792: max_count = 6, min_count = 3;
793: } else {
794: max_count = 7, min_count = 4;
795: }
796: }
797: }
798:
799: /* ===========================================================================
800: * Construct the Huffman tree for the bit lengths and return the index in
801: * bl_order of the last bit length code to send.
802: */
803: local int build_bl_tree(s)
804: deflate_state *s;
805: {
806: int max_blindex; /* index of last bit length code of non zero freq */
807:
808: /* Determine the bit length frequencies for literal and distance trees */
809: scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
810: scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
811:
812: /* Build the bit length tree: */
813: build_tree(s, (tree_desc *)(&(s->bl_desc)));
814: /* opt_len now includes the length of the tree representations, except
815: * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
816: */
817:
818: /* Determine the number of bit length codes to send. The pkzip format
819: * requires that at least 4 bit length codes be sent. (appnote.txt says
820: * 3 but the actual value used is 4.)
821: */
822: for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
823: if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
824: }
825: /* Update opt_len to include the bit length tree and counts */
826: s->opt_len += 3*(max_blindex+1) + 5+5+4;
827: Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
828: s->opt_len, s->static_len));
829:
830: return max_blindex;
831: }
832:
833: /* ===========================================================================
834: * Send the header for a block using dynamic Huffman trees: the counts, the
835: * lengths of the bit length codes, the literal tree and the distance tree.
836: * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
837: */
838: local void send_all_trees(s, lcodes, dcodes, blcodes)
839: deflate_state *s;
840: int lcodes, dcodes, blcodes; /* number of codes for each tree */
841: {
842: int rank; /* index in bl_order */
843:
844: Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
845: Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
846: "too many codes");
847: Tracev((stderr, "\nbl counts: "));
848: send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
849: send_bits(s, dcodes-1, 5);
850: send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
851: for (rank = 0; rank < blcodes; rank++) {
852: Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
853: send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
854: }
855: Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
856:
857: send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
858: Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
859:
860: send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
861: Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
862: }
863:
864: /* ===========================================================================
865: * Send a stored block
866: */
867: void _tr_stored_block(s, buf, stored_len, eof)
868: deflate_state *s;
869: charf *buf; /* input block */
870: ulg stored_len; /* length of input block */
871: int eof; /* true if this is the last block for a file */
872: {
873: send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */
874: #ifdef DEBUG
875: s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
876: s->compressed_len += (stored_len + 4) << 3;
877: #endif
878: copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
879: }
880:
881: /* ===========================================================================
882: * Send one empty static block to give enough lookahead for inflate.
883: * This takes 10 bits, of which 7 may remain in the bit buffer.
884: * The current inflate code requires 9 bits of lookahead. If the
885: * last two codes for the previous block (real code plus EOB) were coded
886: * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
887: * the last real code. In this case we send two empty static blocks instead
888: * of one. (There are no problems if the previous block is stored or fixed.)
889: * To simplify the code, we assume the worst case of last real code encoded
890: * on one bit only.
891: */
892: void _tr_align(s)
893: deflate_state *s;
894: {
895: send_bits(s, STATIC_TREES<<1, 3);
896: send_code(s, END_BLOCK, static_ltree);
897: #ifdef DEBUG
898: s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
899: #endif
900: bi_flush(s);
901: /* Of the 10 bits for the empty block, we have already sent
902: * (10 - bi_valid) bits. The lookahead for the last real code (before
903: * the EOB of the previous block) was thus at least one plus the length
904: * of the EOB plus what we have just sent of the empty static block.
905: */
906: if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
907: send_bits(s, STATIC_TREES<<1, 3);
908: send_code(s, END_BLOCK, static_ltree);
909: #ifdef DEBUG
910: s->compressed_len += 10L;
911: #endif
912: bi_flush(s);
913: }
914: s->last_eob_len = 7;
915: }
916:
917: /* ===========================================================================
918: * Determine the best encoding for the current block: dynamic trees, static
919: * trees or store, and output the encoded block to the zip file.
920: */
921: void _tr_flush_block(s, buf, stored_len, eof)
922: deflate_state *s;
923: charf *buf; /* input block, or NULL if too old */
924: ulg stored_len; /* length of input block */
925: int eof; /* true if this is the last block for a file */
926: {
927: ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
928: int max_blindex = 0; /* index of last bit length code of non zero freq */
929:
930: /* Build the Huffman trees unless a stored block is forced */
931: if (s->level > 0) {
932:
933: /* Check if the file is binary or text */
934: if (stored_len > 0 && s->strm->data_type == Z_UNKNOWN)
935: set_data_type(s);
936:
937: /* Construct the literal and distance trees */
938: build_tree(s, (tree_desc *)(&(s->l_desc)));
939: Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
940: s->static_len));
941:
942: build_tree(s, (tree_desc *)(&(s->d_desc)));
943: Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
944: s->static_len));
945: /* At this point, opt_len and static_len are the total bit lengths of
946: * the compressed block data, excluding the tree representations.
947: */
948:
949: /* Build the bit length tree for the above two trees, and get the index
950: * in bl_order of the last bit length code to send.
951: */
952: max_blindex = build_bl_tree(s);
953:
954: /* Determine the best encoding. Compute the block lengths in bytes. */
955: opt_lenb = (s->opt_len+3+7)>>3;
956: static_lenb = (s->static_len+3+7)>>3;
957:
958: Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
959: opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
960: s->last_lit));
961:
962: if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
963:
964: } else {
965: Assert(buf != (char*)0, "lost buf");
966: opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
967: }
968:
969: #ifdef FORCE_STORED
970: if (buf != (char*)0) { /* force stored block */
971: #else
972: if (stored_len+4 <= opt_lenb && buf != (char*)0) {
973: /* 4: two words for the lengths */
974: #endif
975: /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
976: * Otherwise we can't have processed more than WSIZE input bytes since
977: * the last block flush, because compression would have been
978: * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
979: * transform a block into a stored block.
980: */
981: _tr_stored_block(s, buf, stored_len, eof);
982:
983: #ifdef FORCE_STATIC
984: } else if (static_lenb >= 0) { /* force static trees */
985: #else
986: } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
987: #endif
988: send_bits(s, (STATIC_TREES<<1)+eof, 3);
989: compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
990: #ifdef DEBUG
991: s->compressed_len += 3 + s->static_len;
992: #endif
993: } else {
994: send_bits(s, (DYN_TREES<<1)+eof, 3);
995: send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
996: max_blindex+1);
997: compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
998: #ifdef DEBUG
999: s->compressed_len += 3 + s->opt_len;
1000: #endif
1001: }
1002: Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1003: /* The above check is made mod 2^32, for files larger than 512 MB
1004: * and uLong implemented on 32 bits.
1005: */
1006: init_block(s);
1007:
1008: if (eof) {
1009: bi_windup(s);
1010: #ifdef DEBUG
1011: s->compressed_len += 7; /* align on byte boundary */
1012: #endif
1013: }
1014: Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
1015: s->compressed_len-7*eof));
1016: }
1017:
1018: /* ===========================================================================
1019: * Save the match info and tally the frequency counts. Return true if
1020: * the current block must be flushed.
1021: */
1022: int _tr_tally (s, dist, lc)
1023: deflate_state *s;
1024: unsigned dist; /* distance of matched string */
1025: unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
1026: {
1027: s->d_buf[s->last_lit] = (ush)dist;
1028: s->l_buf[s->last_lit++] = (uch)lc;
1029: if (dist == 0) {
1030: /* lc is the unmatched char */
1031: s->dyn_ltree[lc].Freq++;
1032: } else {
1033: s->matches++;
1034: /* Here, lc is the match length - MIN_MATCH */
1035: dist--; /* dist = match distance - 1 */
1036: Assert((ush)dist < (ush)MAX_DIST(s) &&
1037: (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1038: (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
1039:
1040: s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
1041: s->dyn_dtree[d_code(dist)].Freq++;
1042: }
1043:
1044: #ifdef TRUNCATE_BLOCK
1045: /* Try to guess if it is profitable to stop the current block here */
1046: if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1047: /* Compute an upper bound for the compressed length */
1048: ulg out_length = (ulg)s->last_lit*8L;
1049: ulg in_length = (ulg)((long)s->strstart - s->block_start);
1050: int dcode;
1051: for (dcode = 0; dcode < D_CODES; dcode++) {
1052: out_length += (ulg)s->dyn_dtree[dcode].Freq *
1053: (5L+extra_dbits[dcode]);
1054: }
1055: out_length >>= 3;
1056: Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
1057: s->last_lit, in_length, out_length,
1058: 100L - out_length*100L/in_length));
1059: if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1060: }
1061: #endif
1062: return (s->last_lit == s->lit_bufsize-1);
1063: /* We avoid equality with lit_bufsize because of wraparound at 64K
1064: * on 16 bit machines and because stored blocks are restricted to
1065: * 64K-1 bytes.
1066: */
1067: }
1068:
1069: /* ===========================================================================
1070: * Send the block data compressed using the given Huffman trees
1071: */
1072: local void compress_block(s, ltree, dtree)
1073: deflate_state *s;
1074: ct_data *ltree; /* literal tree */
1075: ct_data *dtree; /* distance tree */
1076: {
1077: unsigned dist; /* distance of matched string */
1078: int lc; /* match length or unmatched char (if dist == 0) */
1079: unsigned lx = 0; /* running index in l_buf */
1080: unsigned code; /* the code to send */
1081: int extra; /* number of extra bits to send */
1082:
1083: if (s->last_lit != 0) do {
1084: dist = s->d_buf[lx];
1085: lc = s->l_buf[lx++];
1086: if (dist == 0) {
1087: send_code(s, lc, ltree); /* send a literal byte */
1088: Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1089: } else {
1090: /* Here, lc is the match length - MIN_MATCH */
1091: code = _length_code[lc];
1092: send_code(s, code+LITERALS+1, ltree); /* send the length code */
1093: extra = extra_lbits[code];
1094: if (extra != 0) {
1095: lc -= base_length[code];
1096: send_bits(s, lc, extra); /* send the extra length bits */
1097: }
1098: dist--; /* dist is now the match distance - 1 */
1099: code = d_code(dist);
1100: Assert (code < D_CODES, "bad d_code");
1101:
1102: send_code(s, code, dtree); /* send the distance code */
1103: extra = extra_dbits[code];
1104: if (extra != 0) {
1105: dist -= base_dist[code];
1106: send_bits(s, dist, extra); /* send the extra distance bits */
1107: }
1108: } /* literal or match pair ? */
1109:
1110: /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
1111: Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1112: "pendingBuf overflow");
1113:
1114: } while (lx < s->last_lit);
1115:
1116: send_code(s, END_BLOCK, ltree);
1117: s->last_eob_len = ltree[END_BLOCK].Len;
1118: }
1119:
1120: /* ===========================================================================
1121: * Set the data type to BINARY or TEXT, using a crude approximation:
1122: * set it to Z_TEXT if all symbols are either printable characters (33 to 255)
1123: * or white spaces (9 to 13, or 32); or set it to Z_BINARY otherwise.
1124: * IN assertion: the fields Freq of dyn_ltree are set.
1125: */
1126: local void set_data_type(s)
1127: deflate_state *s;
1128: {
1129: int n;
1130:
1131: for (n = 0; n < 9; n++)
1132: if (s->dyn_ltree[n].Freq != 0)
1133: break;
1134: if (n == 9)
1135: for (n = 14; n < 32; n++)
1136: if (s->dyn_ltree[n].Freq != 0)
1137: break;
1138: s->strm->data_type = (n == 32) ? Z_TEXT : Z_BINARY;
1139: }
1140:
1141: /* ===========================================================================
1142: * Reverse the first len bits of a code, using straightforward code (a faster
1143: * method would use a table)
1144: * IN assertion: 1 <= len <= 15
1145: */
1146: local unsigned bi_reverse(code, len)
1147: unsigned code; /* the value to invert */
1148: int len; /* its bit length */
1149: {
1150: register unsigned res = 0;
1151: do {
1152: res |= code & 1;
1153: code >>= 1, res <<= 1;
1154: } while (--len > 0);
1155: return res >> 1;
1156: }
1157:
1158: /* ===========================================================================
1159: * Flush the bit buffer, keeping at most 7 bits in it.
1160: */
1161: local void bi_flush(s)
1162: deflate_state *s;
1163: {
1164: if (s->bi_valid == 16) {
1165: put_short(s, s->bi_buf);
1166: s->bi_buf = 0;
1167: s->bi_valid = 0;
1168: } else if (s->bi_valid >= 8) {
1169: put_byte(s, (Byte)s->bi_buf);
1170: s->bi_buf >>= 8;
1171: s->bi_valid -= 8;
1172: }
1173: }
1174:
1175: /* ===========================================================================
1176: * Flush the bit buffer and align the output on a byte boundary
1177: */
1178: local void bi_windup(s)
1179: deflate_state *s;
1180: {
1181: if (s->bi_valid > 8) {
1182: put_short(s, s->bi_buf);
1183: } else if (s->bi_valid > 0) {
1184: put_byte(s, (Byte)s->bi_buf);
1185: }
1186: s->bi_buf = 0;
1187: s->bi_valid = 0;
1188: #ifdef DEBUG
1189: s->bits_sent = (s->bits_sent+7) & ~7;
1190: #endif
1191: }
1192:
1193: /* ===========================================================================
1194: * Copy a stored block, storing first the length and its
1195: * one's complement if requested.
1196: */
1197: local void copy_block(s, buf, len, header)
1198: deflate_state *s;
1199: charf *buf; /* the input data */
1200: unsigned len; /* its length */
1201: int header; /* true if block header must be written */
1202: {
1203: bi_windup(s); /* align on byte boundary */
1204: s->last_eob_len = 8; /* enough lookahead for inflate */
1205:
1206: if (header) {
1207: put_short(s, (ush)len);
1208: put_short(s, (ush)~len);
1209: #ifdef DEBUG
1210: s->bits_sent += 2*16;
1211: #endif
1212: }
1213: #ifdef DEBUG
1214: s->bits_sent += (ulg)len<<3;
1215: #endif
1216: while (len--) {
1217: put_byte(s, *buf++);
1218: }
1219: }
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