+++ /dev/null
-/* 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, const ct_data *ltree,
- const 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, static_ltree, 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, s->dyn_ltree, 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;
- const ct_data *ltree; /* literal tree */
- const 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++);
- }
-}
git.samba.org / samba.git / blobdiff