Wei Chang Shen
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by 
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Diff: png/trees.c
- Revision:
- 2:0e2ef1edf01b
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/png/trees.c Thu Jun 02 04:52:54 2016 +0000
@@ -0,0 +1,1220 @@
+/* trees.c -- output deflated data using Huffman coding
+ * Copyright (C) 1995-2005 Jean-loup Gailly
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+/*
+ * ALGORITHM
+ *
+ * The "deflation" process uses several Huffman trees. The more
+ * common source values are represented by shorter bit sequences.
+ *
+ * Each code tree is stored in a compressed form which is itself
+ * a Huffman encoding of the lengths of all the code strings (in
+ * ascending order by source values). The actual code strings are
+ * reconstructed from the lengths in the inflate process, as described
+ * in the deflate specification.
+ *
+ * REFERENCES
+ *
+ * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
+ * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
+ *
+ * Storer, James A.
+ * Data Compression: Methods and Theory, pp. 49-50.
+ * Computer Science Press, 1988. ISBN 0-7167-8156-5.
+ *
+ * Sedgewick, R.
+ * Algorithms, p290.
+ * Addison-Wesley, 1983. ISBN 0-201-06672-6.
+ */
+
+/* @(#) $Id$ */
+
+/* #define GEN_TREES_H */
+
+#include "deflate.h"
+
+#ifdef DEBUG
+# include <ctype.h>
+#endif
+
+/* ===========================================================================
+ * Constants
+ */
+
+#define MAX_BL_BITS 7
+/* Bit length codes must not exceed MAX_BL_BITS bits */
+
+#define END_BLOCK 256
+/* end of block literal code */
+
+#define REP_3_6 16
+/* repeat previous bit length 3-6 times (2 bits of repeat count) */
+
+#define REPZ_3_10 17
+/* repeat a zero length 3-10 times (3 bits of repeat count) */
+
+#define REPZ_11_138 18
+/* repeat a zero length 11-138 times (7 bits of repeat count) */
+
+local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
+ = {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};
+
+local const int extra_dbits[D_CODES] /* extra bits for each distance code */
+ = {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};
+
+local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
+ = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
+
+local const uch bl_order[BL_CODES]
+ = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
+/* The lengths of the bit length codes are sent in order of decreasing
+ * probability, to avoid transmitting the lengths for unused bit length codes.
+ */
+
+#define Buf_size (8 * 2*sizeof(char))
+/* Number of bits used within bi_buf. (bi_buf might be implemented on
+ * more than 16 bits on some systems.)
+ */
+
+/* ===========================================================================
+ * Local data. These are initialized only once.
+ */
+
+#define DIST_CODE_LEN 512 /* see definition of array dist_code below */
+
+#if defined(GEN_TREES_H) || !defined(STDC)
+/* non ANSI compilers may not accept trees.h */
+
+local ct_data static_ltree[L_CODES+2];
+/* The static literal tree. Since the bit lengths are imposed, there is no
+ * need for the L_CODES extra codes used during heap construction. However
+ * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
+ * below).
+ */
+
+local ct_data static_dtree[D_CODES];
+/* The static distance tree. (Actually a trivial tree since all codes use
+ * 5 bits.)
+ */
+
+uch _dist_code[DIST_CODE_LEN];
+/* Distance codes. The first 256 values correspond to the distances
+ * 3 .. 258, the last 256 values correspond to the top 8 bits of
+ * the 15 bit distances.
+ */
+
+uch _length_code[MAX_MATCH-MIN_MATCH+1];
+/* length code for each normalized match length (0 == MIN_MATCH) */
+
+local int base_length[LENGTH_CODES];
+/* First normalized length for each code (0 = MIN_MATCH) */
+
+local int base_dist[D_CODES];
+/* First normalized distance for each code (0 = distance of 1) */
+
+#else
+# include "trees.h"
+#endif /* GEN_TREES_H */
+
+struct static_tree_desc_s {
+ const ct_data *static_tree; /* static tree or NULL */
+ const intf *extra_bits; /* extra bits for each code or NULL */
+ int extra_base; /* base index for extra_bits */
+ int elems; /* max number of elements in the tree */
+ int max_length; /* max bit length for the codes */
+};
+
+local static_tree_desc static_l_desc =
+{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
+
+local static_tree_desc static_d_desc =
+{static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
+
+local static_tree_desc static_bl_desc =
+{(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
+
+/* ===========================================================================
+ * Local (static) routines in this file.
+ */
+
+local void tr_static_init OF((void));
+local void init_block OF((deflate_state *s));
+local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
+local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
+local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
+local void build_tree OF((deflate_state *s, tree_desc *desc));
+local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
+local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
+local int build_bl_tree OF((deflate_state *s));
+local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
+ int blcodes));
+local void compress_block OF((deflate_state *s, ct_data *ltree,
+ ct_data *dtree));
+local void set_data_type OF((deflate_state *s));
+local unsigned bi_reverse OF((unsigned value, int length));
+local void bi_windup OF((deflate_state *s));
+local void bi_flush OF((deflate_state *s));
+local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
+ int header));
+
+#ifdef GEN_TREES_H
+local void gen_trees_header OF((void));
+#endif
+
+#ifndef DEBUG
+# define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
+ /* Send a code of the given tree. c and tree must not have side effects */
+
+#else /* DEBUG */
+# define send_code(s, c, tree) \
+ { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
+ send_bits(s, tree[c].Code, tree[c].Len); }
+#endif
+
+/* ===========================================================================
+ * Output a short LSB first on the stream.
+ * IN assertion: there is enough room in pendingBuf.
+ */
+#define put_short(s, w) { \
+ put_byte(s, (uch)((w) & 0xff)); \
+ put_byte(s, (uch)((ush)(w) >> 8)); \
+}
+
+/* ===========================================================================
+ * Send a value on a given number of bits.
+ * IN assertion: length <= 16 and value fits in length bits.
+ */
+#ifdef DEBUG
+local void send_bits OF((deflate_state *s, int value, int length));
+
+local void send_bits(s, value, length)
+ deflate_state *s;
+ int value; /* value to send */
+ int length; /* number of bits */
+{
+ Tracevv((stderr," l %2d v %4x ", length, value));
+ Assert(length > 0 && length <= 15, "invalid length");
+ s->bits_sent += (ulg)length;
+
+ /* If not enough room in bi_buf, use (valid) bits from bi_buf and
+ * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
+ * unused bits in value.
+ */
+ if (s->bi_valid > (int)Buf_size - length) {
+ s->bi_buf |= (value << s->bi_valid);
+ put_short(s, s->bi_buf);
+ s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
+ s->bi_valid += length - Buf_size;
+ } else {
+ s->bi_buf |= value << s->bi_valid;
+ s->bi_valid += length;
+ }
+}
+#else /* !DEBUG */
+
+#define send_bits(s, value, length) \
+{ int len = length;\
+ if (s->bi_valid > (int)Buf_size - len) {\
+ int val = value;\
+ s->bi_buf |= (val << s->bi_valid);\
+ put_short(s, s->bi_buf);\
+ s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
+ s->bi_valid += len - Buf_size;\
+ } else {\
+ s->bi_buf |= (value) << s->bi_valid;\
+ s->bi_valid += len;\
+ }\
+}
+#endif /* DEBUG */
+
+
+/* the arguments must not have side effects */
+
+/* ===========================================================================
+ * Initialize the various 'constant' tables.
+ */
+local void tr_static_init()
+{
+#if defined(GEN_TREES_H) || !defined(STDC)
+ static int static_init_done = 0;
+ int n; /* iterates over tree elements */
+ int bits; /* bit counter */
+ int length; /* length value */
+ int code; /* code value */
+ int dist; /* distance index */
+ ush bl_count[MAX_BITS+1];
+ /* number of codes at each bit length for an optimal tree */
+
+ if (static_init_done) return;
+
+ /* For some embedded targets, global variables are not initialized: */
+ static_l_desc.static_tree = static_ltree;
+ static_l_desc.extra_bits = extra_lbits;
+ static_d_desc.static_tree = static_dtree;
+ static_d_desc.extra_bits = extra_dbits;
+ static_bl_desc.extra_bits = extra_blbits;
+
+ /* Initialize the mapping length (0..255) -> length code (0..28) */
+ length = 0;
+ for (code = 0; code < LENGTH_CODES-1; code++) {
+ base_length[code] = length;
+ for (n = 0; n < (1<<extra_lbits[code]); n++) {
+ _length_code[length++] = (uch)code;
+ }
+ }
+ Assert (length == 256, "tr_static_init: length != 256");
+ /* Note that the length 255 (match length 258) can be represented
+ * in two different ways: code 284 + 5 bits or code 285, so we
+ * overwrite length_code[255] to use the best encoding:
+ */
+ _length_code[length-1] = (uch)code;
+
+ /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
+ dist = 0;
+ for (code = 0 ; code < 16; code++) {
+ base_dist[code] = dist;
+ for (n = 0; n < (1<<extra_dbits[code]); n++) {
+ _dist_code[dist++] = (uch)code;
+ }
+ }
+ Assert (dist == 256, "tr_static_init: dist != 256");
+ dist >>= 7; /* from now on, all distances are divided by 128 */
+ for ( ; code < D_CODES; code++) {
+ base_dist[code] = dist << 7;
+ for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
+ _dist_code[256 + dist++] = (uch)code;
+ }
+ }
+ Assert (dist == 256, "tr_static_init: 256+dist != 512");
+
+ /* Construct the codes of the static literal tree */
+ for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
+ n = 0;
+ while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
+ while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
+ while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
+ while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
+ /* Codes 286 and 287 do not exist, but we must include them in the
+ * tree construction to get a canonical Huffman tree (longest code
+ * all ones)
+ */
+ gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
+
+ /* The static distance tree is trivial: */
+ for (n = 0; n < D_CODES; n++) {
+ static_dtree[n].Len = 5;
+ static_dtree[n].Code = bi_reverse((unsigned)n, 5);
+ }
+ static_init_done = 1;
+
+# ifdef GEN_TREES_H
+ gen_trees_header();
+# endif
+#endif /* defined(GEN_TREES_H) || !defined(STDC) */
+}
+
+/* ===========================================================================
+ * Genererate the file trees.h describing the static trees.
+ */
+#ifdef GEN_TREES_H
+# ifndef DEBUG
+# include <stdio.h>
+# endif
+
+# define SEPARATOR(i, last, width) \
+ ((i) == (last)? "\n};\n\n" : \
+ ((i) % (width) == (width)-1 ? ",\n" : ", "))
+
+void gen_trees_header()
+{
+ FILE *header = fopen("trees.h", "w");
+ int i;
+
+ Assert (header != NULL, "Can't open trees.h");
+ fprintf(header,
+ "/* header created automatically with -DGEN_TREES_H */\n\n");
+
+ fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
+ for (i = 0; i < L_CODES+2; i++) {
+ fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
+ static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
+ }
+
+ fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
+ for (i = 0; i < D_CODES; i++) {
+ fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
+ static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
+ }
+
+ fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n");
+ for (i = 0; i < DIST_CODE_LEN; i++) {
+ fprintf(header, "%2u%s", _dist_code[i],
+ SEPARATOR(i, DIST_CODE_LEN-1, 20));
+ }
+
+ fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
+ for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
+ fprintf(header, "%2u%s", _length_code[i],
+ SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
+ }
+
+ fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
+ for (i = 0; i < LENGTH_CODES; i++) {
+ fprintf(header, "%1u%s", base_length[i],
+ SEPARATOR(i, LENGTH_CODES-1, 20));
+ }
+
+ fprintf(header, "local const int base_dist[D_CODES] = {\n");
+ for (i = 0; i < D_CODES; i++) {
+ fprintf(header, "%5u%s", base_dist[i],
+ SEPARATOR(i, D_CODES-1, 10));
+ }
+
+ fclose(header);
+}
+#endif /* GEN_TREES_H */
+
+/* ===========================================================================
+ * Initialize the tree data structures for a new zlib stream.
+ */
+void _tr_init(s)
+ deflate_state *s;
+{
+ tr_static_init();
+
+ s->l_desc.dyn_tree = s->dyn_ltree;
+ s->l_desc.stat_desc = &static_l_desc;
+
+ s->d_desc.dyn_tree = s->dyn_dtree;
+ s->d_desc.stat_desc = &static_d_desc;
+
+ s->bl_desc.dyn_tree = s->bl_tree;
+ s->bl_desc.stat_desc = &static_bl_desc;
+
+ s->bi_buf = 0;
+ s->bi_valid = 0;
+ s->last_eob_len = 8; /* enough lookahead for inflate */
+#ifdef DEBUG
+ s->compressed_len = 0L;
+ s->bits_sent = 0L;
+#endif
+
+ /* Initialize the first block of the first file: */
+ init_block(s);
+}
+
+/* ===========================================================================
+ * Initialize a new block.
+ */
+local void init_block(s)
+ deflate_state *s;
+{
+ int n; /* iterates over tree elements */
+
+ /* Initialize the trees. */
+ for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
+ for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
+ for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
+
+ s->dyn_ltree[END_BLOCK].Freq = 1;
+ s->opt_len = s->static_len = 0L;
+ s->last_lit = s->matches = 0;
+}
+
+#define SMALLEST 1
+/* Index within the heap array of least frequent node in the Huffman tree */
+
+
+/* ===========================================================================
+ * Remove the smallest element from the heap and recreate the heap with
+ * one less element. Updates heap and heap_len.
+ */
+#define pqremove(s, tree, top) \
+{\
+ top = s->heap[SMALLEST]; \
+ s->heap[SMALLEST] = s->heap[s->heap_len--]; \
+ pqdownheap(s, tree, SMALLEST); \
+}
+
+/* ===========================================================================
+ * Compares to subtrees, using the tree depth as tie breaker when
+ * the subtrees have equal frequency. This minimizes the worst case length.
+ */
+#define smaller(tree, n, m, depth) \
+ (tree[n].Freq < tree[m].Freq || \
+ (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
+
+/* ===========================================================================
+ * Restore the heap property by moving down the tree starting at node k,
+ * exchanging a node with the smallest of its two sons if necessary, stopping
+ * when the heap property is re-established (each father smaller than its
+ * two sons).
+ */
+local void pqdownheap(s, tree, k)
+ deflate_state *s;
+ ct_data *tree; /* the tree to restore */
+ int k; /* node to move down */
+{
+ int v = s->heap[k];
+ int j = k << 1; /* left son of k */
+ while (j <= s->heap_len) {
+ /* Set j to the smallest of the two sons: */
+ if (j < s->heap_len &&
+ smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
+ j++;
+ }
+ /* Exit if v is smaller than both sons */
+ if (smaller(tree, v, s->heap[j], s->depth)) break;
+
+ /* Exchange v with the smallest son */
+ s->heap[k] = s->heap[j]; k = j;
+
+ /* And continue down the tree, setting j to the left son of k */
+ j <<= 1;
+ }
+ s->heap[k] = v;
+}
+
+/* ===========================================================================
+ * Compute the optimal bit lengths for a tree and update the total bit length
+ * for the current block.
+ * IN assertion: the fields freq and dad are set, heap[heap_max] and
+ * above are the tree nodes sorted by increasing frequency.
+ * OUT assertions: the field len is set to the optimal bit length, the
+ * array bl_count contains the frequencies for each bit length.
+ * The length opt_len is updated; static_len is also updated if stree is
+ * not null.
+ */
+local void gen_bitlen(s, desc)
+ deflate_state *s;
+ tree_desc *desc; /* the tree descriptor */
+{
+ ct_data *tree = desc->dyn_tree;
+ int max_code = desc->max_code;
+ const ct_data *stree = desc->stat_desc->static_tree;
+ const intf *extra = desc->stat_desc->extra_bits;
+ int base = desc->stat_desc->extra_base;
+ int max_length = desc->stat_desc->max_length;
+ int h; /* heap index */
+ int n, m; /* iterate over the tree elements */
+ int bits; /* bit length */
+ int xbits; /* extra bits */
+ ush f; /* frequency */
+ int overflow = 0; /* number of elements with bit length too large */
+
+ for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
+
+ /* In a first pass, compute the optimal bit lengths (which may
+ * overflow in the case of the bit length tree).
+ */
+ tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
+
+ for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
+ n = s->heap[h];
+ bits = tree[tree[n].Dad].Len + 1;
+ if (bits > max_length) bits = max_length, overflow++;
+ tree[n].Len = (ush)bits;
+ /* We overwrite tree[n].Dad which is no longer needed */
+
+ if (n > max_code) continue; /* not a leaf node */
+
+ s->bl_count[bits]++;
+ xbits = 0;
+ if (n >= base) xbits = extra[n-base];
+ f = tree[n].Freq;
+ s->opt_len += (ulg)f * (bits + xbits);
+ if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
+ }
+ if (overflow == 0) return;
+
+ Trace((stderr,"\nbit length overflow\n"));
+ /* This happens for example on obj2 and pic of the Calgary corpus */
+
+ /* Find the first bit length which could increase: */
+ do {
+ bits = max_length-1;
+ while (s->bl_count[bits] == 0) bits--;
+ s->bl_count[bits]--; /* move one leaf down the tree */
+ s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
+ s->bl_count[max_length]--;
+ /* The brother of the overflow item also moves one step up,
+ * but this does not affect bl_count[max_length]
+ */
+ overflow -= 2;
+ } while (overflow > 0);
+
+ /* Now recompute all bit lengths, scanning in increasing frequency.
+ * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
+ * lengths instead of fixing only the wrong ones. This idea is taken
+ * from 'ar' written by Haruhiko Okumura.)
+ */
+ for (bits = max_length; bits != 0; bits--) {
+ n = s->bl_count[bits];
+ while (n != 0) {
+ m = s->heap[--h];
+ if (m > max_code) continue;
+ if ((unsigned) tree[m].Len != (unsigned) bits) {
+ Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
+ s->opt_len += ((long)bits - (long)tree[m].Len)
+ *(long)tree[m].Freq;
+ tree[m].Len = (ush)bits;
+ }
+ n--;
+ }
+ }
+}
+
+/* ===========================================================================
+ * Generate the codes for a given tree and bit counts (which need not be
+ * optimal).
+ * IN assertion: the array bl_count contains the bit length statistics for
+ * the given tree and the field len is set for all tree elements.
+ * OUT assertion: the field code is set for all tree elements of non
+ * zero code length.
+ */
+local void gen_codes (tree, max_code, bl_count)
+ ct_data *tree; /* the tree to decorate */
+ int max_code; /* largest code with non zero frequency */
+ ushf *bl_count; /* number of codes at each bit length */
+{
+ ush next_code[MAX_BITS+1]; /* next code value for each bit length */
+ ush code = 0; /* running code value */
+ int bits; /* bit index */
+ int n; /* code index */
+
+ /* The distribution counts are first used to generate the code values
+ * without bit reversal.
+ */
+ for (bits = 1; bits <= MAX_BITS; bits++) {
+ next_code[bits] = code = (code + bl_count[bits-1]) << 1;
+ }
+ /* Check that the bit counts in bl_count are consistent. The last code
+ * must be all ones.
+ */
+ Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
+ "inconsistent bit counts");
+ Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
+
+ for (n = 0; n <= max_code; n++) {
+ int len = tree[n].Len;
+ if (len == 0) continue;
+ /* Now reverse the bits */
+ tree[n].Code = bi_reverse(next_code[len]++, len);
+
+ Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
+ n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
+ }
+}
+
+/* ===========================================================================
+ * Construct one Huffman tree and assigns the code bit strings and lengths.
+ * Update the total bit length for the current block.
+ * IN assertion: the field freq is set for all tree elements.
+ * OUT assertions: the fields len and code are set to the optimal bit length
+ * and corresponding code. The length opt_len is updated; static_len is
+ * also updated if stree is not null. The field max_code is set.
+ */
+local void build_tree(s, desc)
+ deflate_state *s;
+ tree_desc *desc; /* the tree descriptor */
+{
+ ct_data *tree = desc->dyn_tree;
+ const ct_data *stree = desc->stat_desc->static_tree;
+ int elems = desc->stat_desc->elems;
+ int n, m; /* iterate over heap elements */
+ int max_code = -1; /* largest code with non zero frequency */
+ int node; /* new node being created */
+
+ /* Construct the initial heap, with least frequent element in
+ * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
+ * heap[0] is not used.
+ */
+ s->heap_len = 0, s->heap_max = HEAP_SIZE;
+
+ for (n = 0; n < elems; n++) {
+ if (tree[n].Freq != 0) {
+ s->heap[++(s->heap_len)] = max_code = n;
+ s->depth[n] = 0;
+ } else {
+ tree[n].Len = 0;
+ }
+ }
+
+ /* The pkzip format requires that at least one distance code exists,
+ * and that at least one bit should be sent even if there is only one
+ * possible code. So to avoid special checks later on we force at least
+ * two codes of non zero frequency.
+ */
+ while (s->heap_len < 2) {
+ node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
+ tree[node].Freq = 1;
+ s->depth[node] = 0;
+ s->opt_len--; if (stree) s->static_len -= stree[node].Len;
+ /* node is 0 or 1 so it does not have extra bits */
+ }
+ desc->max_code = max_code;
+
+ /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
+ * establish sub-heaps of increasing lengths:
+ */
+ for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
+
+ /* Construct the Huffman tree by repeatedly combining the least two
+ * frequent nodes.
+ */
+ node = elems; /* next internal node of the tree */
+ do {
+ pqremove(s, tree, n); /* n = node of least frequency */
+ m = s->heap[SMALLEST]; /* m = node of next least frequency */
+
+ s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
+ s->heap[--(s->heap_max)] = m;
+
+ /* Create a new node father of n and m */
+ tree[node].Freq = tree[n].Freq + tree[m].Freq;
+ s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
+ s->depth[n] : s->depth[m]) + 1);
+ tree[n].Dad = tree[m].Dad = (ush)node;
+#ifdef DUMP_BL_TREE
+ if (tree == s->bl_tree) {
+ fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
+ node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
+ }
+#endif
+ /* and insert the new node in the heap */
+ s->heap[SMALLEST] = node++;
+ pqdownheap(s, tree, SMALLEST);
+
+ } while (s->heap_len >= 2);
+
+ s->heap[--(s->heap_max)] = s->heap[SMALLEST];
+
+ /* At this point, the fields freq and dad are set. We can now
+ * generate the bit lengths.
+ */
+ gen_bitlen(s, (tree_desc *)desc);
+
+ /* The field len is now set, we can generate the bit codes */
+ gen_codes ((ct_data *)tree, max_code, s->bl_count);
+}
+
+/* ===========================================================================
+ * Scan a literal or distance tree to determine the frequencies of the codes
+ * in the bit length tree.
+ */
+local void scan_tree (s, tree, max_code)
+ deflate_state *s;
+ ct_data *tree; /* the tree to be scanned */
+ int max_code; /* and its largest code of non zero frequency */
+{
+ int n; /* iterates over all tree elements */
+ int prevlen = -1; /* last emitted length */
+ int curlen; /* length of current code */
+ int nextlen = tree[0].Len; /* length of next code */
+ int count = 0; /* repeat count of the current code */
+ int max_count = 7; /* max repeat count */
+ int min_count = 4; /* min repeat count */
+
+ if (nextlen == 0) max_count = 138, min_count = 3;
+ tree[max_code+1].Len = (ush)0xffff; /* guard */
+
+ for (n = 0; n <= max_code; n++) {
+ curlen = nextlen; nextlen = tree[n+1].Len;
+ if (++count < max_count && curlen == nextlen) {
+ continue;
+ } else if (count < min_count) {
+ s->bl_tree[curlen].Freq += count;
+ } else if (curlen != 0) {
+ if (curlen != prevlen) s->bl_tree[curlen].Freq++;
+ s->bl_tree[REP_3_6].Freq++;
+ } else if (count <= 10) {
+ s->bl_tree[REPZ_3_10].Freq++;
+ } else {
+ s->bl_tree[REPZ_11_138].Freq++;
+ }
+ count = 0; prevlen = curlen;
+ if (nextlen == 0) {
+ max_count = 138, min_count = 3;
+ } else if (curlen == nextlen) {
+ max_count = 6, min_count = 3;
+ } else {
+ max_count = 7, min_count = 4;
+ }
+ }
+}
+
+/* ===========================================================================
+ * Send a literal or distance tree in compressed form, using the codes in
+ * bl_tree.
+ */
+local void send_tree (s, tree, max_code)
+ deflate_state *s;
+ ct_data *tree; /* the tree to be scanned */
+ int max_code; /* and its largest code of non zero frequency */
+{
+ int n; /* iterates over all tree elements */
+ int prevlen = -1; /* last emitted length */
+ int curlen; /* length of current code */
+ int nextlen = tree[0].Len; /* length of next code */
+ int count = 0; /* repeat count of the current code */
+ int max_count = 7; /* max repeat count */
+ int min_count = 4; /* min repeat count */
+
+ /* tree[max_code+1].Len = -1; */ /* guard already set */
+ if (nextlen == 0) max_count = 138, min_count = 3;
+
+ for (n = 0; n <= max_code; n++) {
+ curlen = nextlen; nextlen = tree[n+1].Len;
+ if (++count < max_count && curlen == nextlen) {
+ continue;
+ } else if (count < min_count) {
+ do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
+
+ } else if (curlen != 0) {
+ if (curlen != prevlen) {
+ send_code(s, curlen, s->bl_tree); count--;
+ }
+ Assert(count >= 3 && count <= 6, " 3_6?");
+ send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
+
+ } else if (count <= 10) {
+ send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
+
+ } else {
+ send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
+ }
+ count = 0; prevlen = curlen;
+ if (nextlen == 0) {
+ max_count = 138, min_count = 3;
+ } else if (curlen == nextlen) {
+ max_count = 6, min_count = 3;
+ } else {
+ max_count = 7, min_count = 4;
+ }
+ }
+}
+
+/* ===========================================================================
+ * Construct the Huffman tree for the bit lengths and return the index in
+ * bl_order of the last bit length code to send.
+ */
+local int build_bl_tree(s)
+ deflate_state *s;
+{
+ int max_blindex; /* index of last bit length code of non zero freq */
+
+ /* Determine the bit length frequencies for literal and distance trees */
+ scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
+ scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
+
+ /* Build the bit length tree: */
+ build_tree(s, (tree_desc *)(&(s->bl_desc)));
+ /* opt_len now includes the length of the tree representations, except
+ * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
+ */
+
+ /* Determine the number of bit length codes to send. The pkzip format
+ * requires that at least 4 bit length codes be sent. (appnote.txt says
+ * 3 but the actual value used is 4.)
+ */
+ for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
+ if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
+ }
+ /* Update opt_len to include the bit length tree and counts */
+ s->opt_len += 3*(max_blindex+1) + 5+5+4;
+ Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
+ s->opt_len, s->static_len));
+
+ return max_blindex;
+}
+
+/* ===========================================================================
+ * Send the header for a block using dynamic Huffman trees: the counts, the
+ * lengths of the bit length codes, the literal tree and the distance tree.
+ * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
+ */
+local void send_all_trees(s, lcodes, dcodes, blcodes)
+ deflate_state *s;
+ int lcodes, dcodes, blcodes; /* number of codes for each tree */
+{
+ int rank; /* index in bl_order */
+
+ Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
+ Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
+ "too many codes");
+ Tracev((stderr, "\nbl counts: "));
+ send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
+ send_bits(s, dcodes-1, 5);
+ send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
+ for (rank = 0; rank < blcodes; rank++) {
+ Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
+ send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
+ }
+ Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
+
+ send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
+ Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
+
+ send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
+ Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
+}
+
+/* ===========================================================================
+ * Send a stored block
+ */
+void _tr_stored_block(s, buf, stored_len, eof)
+ deflate_state *s;
+ charf *buf; /* input block */
+ ulg stored_len; /* length of input block */
+ int eof; /* true if this is the last block for a file */
+{
+ send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */
+#ifdef DEBUG
+ s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
+ s->compressed_len += (stored_len + 4) << 3;
+#endif
+ copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
+}
+
+/* ===========================================================================
+ * Send one empty static block to give enough lookahead for inflate.
+ * This takes 10 bits, of which 7 may remain in the bit buffer.
+ * The current inflate code requires 9 bits of lookahead. If the
+ * last two codes for the previous block (real code plus EOB) were coded
+ * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
+ * the last real code. In this case we send two empty static blocks instead
+ * of one. (There are no problems if the previous block is stored or fixed.)
+ * To simplify the code, we assume the worst case of last real code encoded
+ * on one bit only.
+ */
+void _tr_align(s)
+ deflate_state *s;
+{
+ send_bits(s, STATIC_TREES<<1, 3);
+ send_code(s, END_BLOCK, static_ltree);
+#ifdef DEBUG
+ s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
+#endif
+ bi_flush(s);
+ /* Of the 10 bits for the empty block, we have already sent
+ * (10 - bi_valid) bits. The lookahead for the last real code (before
+ * the EOB of the previous block) was thus at least one plus the length
+ * of the EOB plus what we have just sent of the empty static block.
+ */
+ if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
+ send_bits(s, STATIC_TREES<<1, 3);
+ send_code(s, END_BLOCK, static_ltree);
+#ifdef DEBUG
+ s->compressed_len += 10L;
+#endif
+ bi_flush(s);
+ }
+ s->last_eob_len = 7;
+}
+
+/* ===========================================================================
+ * Determine the best encoding for the current block: dynamic trees, static
+ * trees or store, and output the encoded block to the zip file.
+ */
+void _tr_flush_block(s, buf, stored_len, eof)
+ deflate_state *s;
+ charf *buf; /* input block, or NULL if too old */
+ ulg stored_len; /* length of input block */
+ int eof; /* true if this is the last block for a file */
+{
+ ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
+ int max_blindex = 0; /* index of last bit length code of non zero freq */
+
+ /* Build the Huffman trees unless a stored block is forced */
+ if (s->level > 0) {
+
+ /* Check if the file is binary or text */
+ if (stored_len > 0 && s->strm->data_type == Z_UNKNOWN)
+ set_data_type(s);
+
+ /* Construct the literal and distance trees */
+ build_tree(s, (tree_desc *)(&(s->l_desc)));
+ Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
+ s->static_len));
+
+ build_tree(s, (tree_desc *)(&(s->d_desc)));
+ Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
+ s->static_len));
+ /* At this point, opt_len and static_len are the total bit lengths of
+ * the compressed block data, excluding the tree representations.
+ */
+
+ /* Build the bit length tree for the above two trees, and get the index
+ * in bl_order of the last bit length code to send.
+ */
+ max_blindex = build_bl_tree(s);
+
+ /* Determine the best encoding. Compute the block lengths in bytes. */
+ opt_lenb = (s->opt_len+3+7)>>3;
+ static_lenb = (s->static_len+3+7)>>3;
+
+ Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
+ opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
+ s->last_lit));
+
+ if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
+
+ } else {
+ Assert(buf != (char*)0, "lost buf");
+ opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
+ }
+
+#ifdef FORCE_STORED
+ if (buf != (char*)0) { /* force stored block */
+#else
+ if (stored_len+4 <= opt_lenb && buf != (char*)0) {
+ /* 4: two words for the lengths */
+#endif
+ /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
+ * Otherwise we can't have processed more than WSIZE input bytes since
+ * the last block flush, because compression would have been
+ * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
+ * transform a block into a stored block.
+ */
+ _tr_stored_block(s, buf, stored_len, eof);
+
+#ifdef FORCE_STATIC
+ } else if (static_lenb >= 0) { /* force static trees */
+#else
+ } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
+#endif
+ send_bits(s, (STATIC_TREES<<1)+eof, 3);
+ compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
+#ifdef DEBUG
+ s->compressed_len += 3 + s->static_len;
+#endif
+ } else {
+ send_bits(s, (DYN_TREES<<1)+eof, 3);
+ send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
+ max_blindex+1);
+ compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
+#ifdef DEBUG
+ s->compressed_len += 3 + s->opt_len;
+#endif
+ }
+ Assert (s->compressed_len == s->bits_sent, "bad compressed size");
+ /* The above check is made mod 2^32, for files larger than 512 MB
+ * and uLong implemented on 32 bits.
+ */
+ init_block(s);
+
+ if (eof) {
+ bi_windup(s);
+#ifdef DEBUG
+ s->compressed_len += 7; /* align on byte boundary */
+#endif
+ }
+ Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
+ s->compressed_len-7*eof));
+}
+
+/* ===========================================================================
+ * Save the match info and tally the frequency counts. Return true if
+ * the current block must be flushed.
+ */
+int _tr_tally (s, dist, lc)
+ deflate_state *s;
+ unsigned dist; /* distance of matched string */
+ unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
+{
+ s->d_buf[s->last_lit] = (ush)dist;
+ s->l_buf[s->last_lit++] = (uch)lc;
+ if (dist == 0) {
+ /* lc is the unmatched char */
+ s->dyn_ltree[lc].Freq++;
+ } else {
+ s->matches++;
+ /* Here, lc is the match length - MIN_MATCH */
+ dist--; /* dist = match distance - 1 */
+ Assert((ush)dist < (ush)MAX_DIST(s) &&
+ (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
+ (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
+
+ s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
+ s->dyn_dtree[d_code(dist)].Freq++;
+ }
+
+#ifdef TRUNCATE_BLOCK
+ /* Try to guess if it is profitable to stop the current block here */
+ if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
+ /* Compute an upper bound for the compressed length */
+ ulg out_length = (ulg)s->last_lit*8L;
+ ulg in_length = (ulg)((long)s->strstart - s->block_start);
+ int dcode;
+ for (dcode = 0; dcode < D_CODES; dcode++) {
+ out_length += (ulg)s->dyn_dtree[dcode].Freq *
+ (5L+extra_dbits[dcode]);
+ }
+ out_length >>= 3;
+ Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
+ s->last_lit, in_length, out_length,
+ 100L - out_length*100L/in_length));
+ if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
+ }
+#endif
+ return (s->last_lit == s->lit_bufsize-1);
+ /* We avoid equality with lit_bufsize because of wraparound at 64K
+ * on 16 bit machines and because stored blocks are restricted to
+ * 64K-1 bytes.
+ */
+}
+
+/* ===========================================================================
+ * Send the block data compressed using the given Huffman trees
+ */
+local void compress_block(s, ltree, dtree)
+ deflate_state *s;
+ ct_data *ltree; /* literal tree */
+ ct_data *dtree; /* distance tree */
+{
+ unsigned dist; /* distance of matched string */
+ int lc; /* match length or unmatched char (if dist == 0) */
+ unsigned lx = 0; /* running index in l_buf */
+ unsigned code; /* the code to send */
+ int extra; /* number of extra bits to send */
+
+ if (s->last_lit != 0) do {
+ dist = s->d_buf[lx];
+ lc = s->l_buf[lx++];
+ if (dist == 0) {
+ send_code(s, lc, ltree); /* send a literal byte */
+ Tracecv(isgraph(lc), (stderr," '%c' ", lc));
+ } else {
+ /* Here, lc is the match length - MIN_MATCH */
+ code = _length_code[lc];
+ send_code(s, code+LITERALS+1, ltree); /* send the length code */
+ extra = extra_lbits[code];
+ if (extra != 0) {
+ lc -= base_length[code];
+ send_bits(s, lc, extra); /* send the extra length bits */
+ }
+ dist--; /* dist is now the match distance - 1 */
+ code = d_code(dist);
+ Assert (code < D_CODES, "bad d_code");
+
+ send_code(s, code, dtree); /* send the distance code */
+ extra = extra_dbits[code];
+ if (extra != 0) {
+ dist -= base_dist[code];
+ send_bits(s, dist, extra); /* send the extra distance bits */
+ }
+ } /* literal or match pair ? */
+
+ /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
+ Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
+ "pendingBuf overflow");
+
+ } while (lx < s->last_lit);
+
+ send_code(s, END_BLOCK, ltree);
+ s->last_eob_len = ltree[END_BLOCK].Len;
+}
+
+/* ===========================================================================
+ * Set the data type to BINARY or TEXT, using a crude approximation:
+ * set it to Z_TEXT if all symbols are either printable characters (33 to 255)
+ * or white spaces (9 to 13, or 32); or set it to Z_BINARY otherwise.
+ * IN assertion: the fields Freq of dyn_ltree are set.
+ */
+local void set_data_type(s)
+ deflate_state *s;
+{
+ int n;
+
+ for (n = 0; n < 9; n++)
+ if (s->dyn_ltree[n].Freq != 0)
+ break;
+ if (n == 9)
+ for (n = 14; n < 32; n++)
+ if (s->dyn_ltree[n].Freq != 0)
+ break;
+ s->strm->data_type = (n == 32) ? Z_TEXT : Z_BINARY;
+}
+
+/* ===========================================================================
+ * Reverse the first len bits of a code, using straightforward code (a faster
+ * method would use a table)
+ * IN assertion: 1 <= len <= 15
+ */
+local unsigned bi_reverse(code, len)
+ unsigned code; /* the value to invert */
+ int len; /* its bit length */
+{
+ register unsigned res = 0;
+ do {
+ res |= code & 1;
+ code >>= 1, res <<= 1;
+ } while (--len > 0);
+ return res >> 1;
+}
+
+/* ===========================================================================
+ * Flush the bit buffer, keeping at most 7 bits in it.
+ */
+local void bi_flush(s)
+ deflate_state *s;
+{
+ if (s->bi_valid == 16) {
+ put_short(s, s->bi_buf);
+ s->bi_buf = 0;
+ s->bi_valid = 0;
+ } else if (s->bi_valid >= 8) {
+ put_byte(s, (Byte)s->bi_buf);
+ s->bi_buf >>= 8;
+ s->bi_valid -= 8;
+ }
+}
+
+/* ===========================================================================
+ * Flush the bit buffer and align the output on a byte boundary
+ */
+local void bi_windup(s)
+ deflate_state *s;
+{
+ if (s->bi_valid > 8) {
+ put_short(s, s->bi_buf);
+ } else if (s->bi_valid > 0) {
+ put_byte(s, (Byte)s->bi_buf);
+ }
+ s->bi_buf = 0;
+ s->bi_valid = 0;
+#ifdef DEBUG
+ s->bits_sent = (s->bits_sent+7) & ~7;
+#endif
+}
+
+/* ===========================================================================
+ * Copy a stored block, storing first the length and its
+ * one's complement if requested.
+ */
+local void copy_block(s, buf, len, header)
+ deflate_state *s;
+ charf *buf; /* the input data */
+ unsigned len; /* its length */
+ int header; /* true if block header must be written */
+{
+ bi_windup(s); /* align on byte boundary */
+ s->last_eob_len = 8; /* enough lookahead for inflate */
+
+ if (header) {
+ put_short(s, (ush)len);
+ put_short(s, (ush)~len);
+#ifdef DEBUG
+ s->bits_sent += 2*16;
+#endif
+ }
+#ifdef DEBUG
+ s->bits_sent += (ulg)len<<3;
+#endif
+ while (len--) {
+ put_byte(s, *buf++);
+ }
+}
+