c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* trees.c -- output deflated data using Huffman coding
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Copyright (C) 1995-2005 Jean-loup Gailly
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * For conditions of distribution and use, see copyright notice in zlib.h
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl#pragma ident "%Z%%M% %I% %E% SMI"
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * ALGORITHM
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * The "deflation" process uses several Huffman trees. The more
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * common source values are represented by shorter bit sequences.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Each code tree is stored in a compressed form which is itself
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * a Huffman encoding of the lengths of all the code strings (in
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * ascending order by source values). The actual code strings are
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * reconstructed from the lengths in the inflate process, as described
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * in the deflate specification.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * REFERENCES
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Storer, James A.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Data Compression: Methods and Theory, pp. 49-50.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Computer Science Press, 1988. ISBN 0-7167-8156-5.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Sedgewick, R.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Algorithms, p290.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Addison-Wesley, 1983. ISBN 0-201-06672-6.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* #define GEN_TREES_H */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Constants
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* Bit length codes must not exceed MAX_BL_BITS bits */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* end of block literal code */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* repeat previous bit length 3-6 times (2 bits of repeat count) */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* repeat a zero length 3-10 times (3 bits of repeat count) */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* repeat a zero length 11-138 times (7 bits of repeat count) */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl = {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};
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal const int extra_dbits[D_CODES] /* extra bits for each distance code */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl = {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};
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* The lengths of the bit length codes are sent in order of decreasing
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * probability, to avoid transmitting the lengths for unused bit length codes.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* Number of bits used within bi_buf. (bi_buf might be implemented on
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * more than 16 bits on some systems.)
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Local data. These are initialized only once.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl#define DIST_CODE_LEN 512 /* see definition of array dist_code below */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* non ANSI compilers may not accept trees.h */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* The static literal tree. Since the bit lengths are imposed, there is no
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * need for the L_CODES extra codes used during heap construction. However
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* The static distance tree. (Actually a trivial tree since all codes use
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * 5 bits.)
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* Distance codes. The first 256 values correspond to the distances
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * 3 .. 258, the last 256 values correspond to the top 8 bits of
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * the 15 bit distances.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* length code for each normalized match length (0 == MIN_MATCH) */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* First normalized length for each code (0 = MIN_MATCH) */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* First normalized distance for each code (0 = distance of 1) */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl#endif /* GEN_TREES_H */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl const intf *extra_bits; /* extra bits for each code or NULL */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl{(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Local (static) routines in this file.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal void gen_bitlen OF((deflate_state *s, tree_desc *desc));
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal void build_tree OF((deflate_state *s, tree_desc *desc));
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal void compress_block OF((deflate_state *s, ct_data *ltree,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal unsigned bi_reverse OF((unsigned value, int length));
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal void copy_block OF((deflate_state *s, charf *buf, unsigned len,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl# define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Send a code of the given tree. c and tree must not have side effects */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl#else /* DEBUG */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Output a short LSB first on the stream.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * IN assertion: there is enough room in pendingBuf.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Send a value on a given number of bits.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * IN assertion: length <= 16 and value fits in length bits.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahllocal void send_bits OF((deflate_state *s, int value, int length));
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* If not enough room in bi_buf, use (valid) bits from bi_buf and
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * unused bits in value.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl#else /* !DEBUG */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl#endif /* DEBUG */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* the arguments must not have side effects */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Initialize the various 'constant' tables.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int n; /* iterates over tree elements */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* number of codes at each bit length for an optimal tree */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* For some embedded targets, global variables are not initialized: */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Initialize the mapping length (0..255) -> length code (0..28) */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Assert (length == 256, "tr_static_init: length != 256");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Note that the length 255 (match length 258) can be represented
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * in two different ways: code 284 + 5 bits or code 285, so we
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * overwrite length_code[255] to use the best encoding:
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl dist >>= 7; /* from now on, all distances are divided by 128 */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Assert (dist == 256, "tr_static_init: 256+dist != 512");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Construct the codes of the static literal tree */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Codes 286 and 287 do not exist, but we must include them in the
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * tree construction to get a canonical Huffman tree (longest code
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * all ones)
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* The static distance tree is trivial: */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (n = 0; n < D_CODES; n++) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl#endif /* defined(GEN_TREES_H) || !defined(STDC) */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Genererate the file trees.h describing the static trees.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl "/* header created automatically with -DGEN_TREES_H */\n\n");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (i = 0; i < D_CODES; i++) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (i = 0; i < DIST_CODE_LEN; i++) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (i = 0; i < LENGTH_CODES; i++) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl fprintf(header, "local const int base_dist[D_CODES] = {\n");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (i = 0; i < D_CODES; i++) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl#endif /* GEN_TREES_H */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Initialize the tree data structures for a new zlib stream.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Initialize the first block of the first file: */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Initialize a new block.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int n; /* iterates over tree elements */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Initialize the trees. */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* Index within the heap array of least frequent node in the Huffman tree */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Remove the smallest element from the heap and recreate the heap with
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * one less element. Updates heap and heap_len.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Compares to subtrees, using the tree depth as tie breaker when
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * the subtrees have equal frequency. This minimizes the worst case length.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Restore the heap property by moving down the tree starting at node k,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * exchanging a node with the smallest of its two sons if necessary, stopping
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * when the heap property is re-established (each father smaller than its
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * two sons).
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int k; /* node to move down */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int v = s->heap[k];
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl while (j <= s->heap_len) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Set j to the smallest of the two sons: */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (j < s->heap_len &&
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Exit if v is smaller than both sons */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Exchange v with the smallest son */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* And continue down the tree, setting j to the left son of k */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl s->heap[k] = v;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Compute the optimal bit lengths for a tree and update the total bit length
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * for the current block.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * IN assertion: the fields freq and dad are set, heap[heap_max] and
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * above are the tree nodes sorted by increasing frequency.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * OUT assertions: the field len is set to the optimal bit length, the
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * array bl_count contains the frequencies for each bit length.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * The length opt_len is updated; static_len is also updated if stree is
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * not null.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int h; /* heap index */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int n, m; /* iterate over the tree elements */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int overflow = 0; /* number of elements with bit length too large */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* In a first pass, compute the optimal bit lengths (which may
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * overflow in the case of the bit length tree).
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl n = s->heap[h];
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* We overwrite tree[n].Dad which is no longer needed */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (overflow == 0) return;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* This happens for example on obj2 and pic of the Calgary corpus */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Find the first bit length which could increase: */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* The brother of the overflow item also moves one step up,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * but this does not affect bl_count[max_length]
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl } while (overflow > 0);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Now recompute all bit lengths, scanning in increasing frequency.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * lengths instead of fixing only the wrong ones. This idea is taken
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * from 'ar' written by Haruhiko Okumura.)
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl while (n != 0) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl m = s->heap[--h];
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (m > max_code) continue;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Generate the codes for a given tree and bit counts (which need not be
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * optimal).
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * IN assertion: the array bl_count contains the bit length statistics for
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * the given tree and the field len is set for all tree elements.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * OUT assertion: the field code is set for all tree elements of non
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * zero code length.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int max_code; /* largest code with non zero frequency */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl ushf *bl_count; /* number of codes at each bit length */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl ush next_code[MAX_BITS+1]; /* next code value for each bit length */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int n; /* code index */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* The distribution counts are first used to generate the code values
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * without bit reversal.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl next_code[bits] = code = (code + bl_count[bits-1]) << 1;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Check that the bit counts in bl_count are consistent. The last code
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * must be all ones.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl "inconsistent bit counts");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (n = 0; n <= max_code; n++) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (len == 0) continue;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Now reverse the bits */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Construct one Huffman tree and assigns the code bit strings and lengths.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Update the total bit length for the current block.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * IN assertion: the field freq is set for all tree elements.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * OUT assertions: the fields len and code are set to the optimal bit length
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * and corresponding code. The length opt_len is updated; static_len is
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * also updated if stree is not null. The field max_code is set.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int n, m; /* iterate over heap elements */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int max_code = -1; /* largest code with non zero frequency */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Construct the initial heap, with least frequent element in
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * heap[0] is not used.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (n = 0; n < elems; n++) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl s->depth[n] = 0;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* The pkzip format requires that at least one distance code exists,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * and that at least one bit should be sent even if there is only one
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * possible code. So to avoid special checks later on we force at least
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * two codes of non zero frequency.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl s->opt_len--; if (stree) s->static_len -= stree[node].Len;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* node is 0 or 1 so it does not have extra bits */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * establish sub-heaps of increasing lengths:
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Construct the Huffman tree by repeatedly combining the least two
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * frequent nodes.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl m = s->heap[SMALLEST]; /* m = node of next least frequency */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Create a new node father of n and m */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* and insert the new node in the heap */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* At this point, the fields freq and dad are set. We can now
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * generate the bit lengths.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* The field len is now set, we can generate the bit codes */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Scan a literal or distance tree to determine the frequencies of the codes
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * in the bit length tree.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int max_code; /* and its largest code of non zero frequency */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int n; /* iterates over all tree elements */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (n = 0; n <= max_code; n++) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl } else if (curlen != 0) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (nextlen == 0) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Send a literal or distance tree in compressed form, using the codes in
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * bl_tree.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int max_code; /* and its largest code of non zero frequency */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int n; /* iterates over all tree elements */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* tree[max_code+1].Len = -1; */ /* guard already set */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (n = 0; n <= max_code; n++) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl } else if (curlen != 0) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (nextlen == 0) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Construct the Huffman tree for the bit lengths and return the index in
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * bl_order of the last bit length code to send.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int max_blindex; /* index of last bit length code of non zero freq */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Determine the bit length frequencies for literal and distance trees */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Build the bit length tree: */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* opt_len now includes the length of the tree representations, except
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Determine the number of bit length codes to send. The pkzip format
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * requires that at least 4 bit length codes be sent. (appnote.txt says
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * 3 but the actual value used is 4.)
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Update opt_len to include the bit length tree and counts */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Send the header for a block using dynamic Huffman trees: the counts, the
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * lengths of the bit length codes, the literal tree and the distance tree.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int lcodes, dcodes, blcodes; /* number of codes for each tree */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl "too many codes");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Send a stored block
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int eof; /* true if this is the last block for a file */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Send one empty static block to give enough lookahead for inflate.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * This takes 10 bits, of which 7 may remain in the bit buffer.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * The current inflate code requires 9 bits of lookahead. If the
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * last two codes for the previous block (real code plus EOB) were coded
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * the last real code. In this case we send two empty static blocks instead
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * of one. (There are no problems if the previous block is stored or fixed.)
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * To simplify the code, we assume the worst case of last real code encoded
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * on one bit only.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Of the 10 bits for the empty block, we have already sent
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * (10 - bi_valid) bits. The lookahead for the last real code (before
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * the EOB of the previous block) was thus at least one plus the length
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * of the EOB plus what we have just sent of the empty static block.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Determine the best encoding for the current block: dynamic trees, static
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * trees or store, and output the encoded block to the zip file.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int eof; /* true if this is the last block for a file */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int max_blindex = 0; /* index of last bit length code of non zero freq */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Build the Huffman trees unless a stored block is forced */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (s->level > 0) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Check if the file is binary or text */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Construct the literal and distance trees */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* At this point, opt_len and static_len are the total bit lengths of
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * the compressed block data, excluding the tree representations.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Build the bit length tree for the above two trees, and get the index
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * in bl_order of the last bit length code to send.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Determine the best encoding. Compute the block lengths in bytes. */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* 4: two words for the lengths */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Otherwise we can't have processed more than WSIZE input bytes since
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * the last block flush, because compression would have been
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * transform a block into a stored block.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Assert (s->compressed_len == s->bits_sent, "bad compressed size");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* The above check is made mod 2^32, for files larger than 512 MB
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * and uLong implemented on 32 bits.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Save the match info and tally the frequency counts. Return true if
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * the current block must be flushed.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (dist == 0) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* lc is the unmatched char */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Here, lc is the match length - MIN_MATCH */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Try to guess if it is profitable to stop the current block here */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Compute an upper bound for the compressed length */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl ulg in_length = (ulg)((long)s->strstart - s->block_start);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* We avoid equality with lit_bufsize because of wraparound at 64K
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * on 16 bit machines and because stored blocks are restricted to
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * 64K-1 bytes.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Send the block data compressed using the given Huffman trees
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl int lc; /* match length or unmatched char (if dist == 0) */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (s->last_lit != 0) do {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (dist == 0) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Here, lc is the match length - MIN_MATCH */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl send_code(s, code+LITERALS+1, ltree); /* send the length code */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (extra != 0) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl send_bits(s, lc, extra); /* send the extra length bits */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (extra != 0) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl send_bits(s, dist, extra); /* send the extra distance bits */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl } /* literal or match pair ? */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl "pendingBuf overflow");
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Set the data type to BINARY or TEXT, using a crude approximation:
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * set it to Z_TEXT if all symbols are either printable characters (33 to 255)
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * or white spaces (9 to 13, or 32); or set it to Z_BINARY otherwise.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * IN assertion: the fields Freq of dyn_ltree are set.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl for (n = 0; n < 9; n++)
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl if (n == 9)
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Reverse the first len bits of a code, using straightforward code (a faster
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * method would use a table)
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * IN assertion: 1 <= len <= 15
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl } while (--len > 0);
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Flush the bit buffer, keeping at most 7 bits in it.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Flush the bit buffer and align the output on a byte boundary
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl } else if (s->bi_valid > 0) {
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl/* ===========================================================================
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * Copy a stored block, storing first the length and its
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl * one's complement if requested.
c9431fa1e59a88c2f0abf611f25b97af964449e5ahl while (len--) {