+/* trees.c -- output deflated data using Huffman coding
+ * Copyright (C) 1992-1993 Jean-loup Gailly
+ * This is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License, see the file COPYING.
+ */
+
+/*
+ * PURPOSE
+ *
+ * Encode various sets of source values using variable-length
+ * binary code trees.
+ *
+ * DISCUSSION
+ *
+ * The PKZIP "deflation" process uses several Huffman trees. The more
+ * common source values are represented by shorter bit sequences.
+ *
+ * Each code tree is stored in the ZIP file 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 UNZIP process, as described in the "application note"
+ * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
+ *
+ * REFERENCES
+ *
+ * Lynch, Thomas J.
+ * Data Compression: Techniques and Applications, pp. 53-55.
+ * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
+ *
+ * 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.
+ *
+ * INTERFACE
+ *
+ * void ct_init (ush *attr, int *methodp)
+ * Allocate the match buffer, initialize the various tables and save
+ * the location of the internal file attribute (ascii/binary) and
+ * method (DEFLATE/STORE)
+ *
+ * void ct_tally (int dist, int lc);
+ * Save the match info and tally the frequency counts.
+ *
+ * long flush_block (char *buf, ulg stored_len, int eof)
+ * Determine the best encoding for the current block: dynamic trees,
+ * static trees or store, and output the encoded block to the zip
+ * file. Returns the total compressed length for the file so far.
+ *
+ */
+
+#include <ctype.h>
+
+#include "tailor.h"
+#include "gzip.h"
+
+#ifdef RCSID
+static char rcsid[] = "$Id: trees.c,v 0.12 1993/06/10 13:27:54 jloup Exp $";
+#endif
+
+/* ===========================================================================
+ * Constants
+ */
+
+#define MAX_BITS 15
+/* All codes must not exceed MAX_BITS bits */
+
+#define MAX_BL_BITS 7
+/* Bit length codes must not exceed MAX_BL_BITS bits */
+
+#define LENGTH_CODES 29
+/* number of length codes, not counting the special END_BLOCK code */
+
+#define LITERALS 256
+/* number of literal bytes 0..255 */
+
+#define END_BLOCK 256
+/* end of block literal code */
+
+#define L_CODES (LITERALS+1+LENGTH_CODES)
+/* number of Literal or Length codes, including the END_BLOCK code */
+
+#define D_CODES 30
+/* number of distance codes */
+
+#define BL_CODES 19
+/* number of codes used to transfer the bit lengths */
+
+
+local int near 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 int near 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 int near 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};
+
+#define STORED_BLOCK 0
+#define STATIC_TREES 1
+#define DYN_TREES 2
+/* The three kinds of block type */
+
+#ifndef LIT_BUFSIZE
+# ifdef SMALL_MEM
+# define LIT_BUFSIZE 0x2000
+# else
+# ifdef MEDIUM_MEM
+# define LIT_BUFSIZE 0x4000
+# else
+# define LIT_BUFSIZE 0x8000
+# endif
+# endif
+#endif
+#ifndef DIST_BUFSIZE
+# define DIST_BUFSIZE LIT_BUFSIZE
+#endif
+/* Sizes of match buffers for literals/lengths and distances. There are
+ * 4 reasons for limiting LIT_BUFSIZE to 64K:
+ * - frequencies can be kept in 16 bit counters
+ * - if compression is not successful for the first block, all input data is
+ * still in the window so we can still emit a stored block even when input
+ * comes from standard input. (This can also be done for all blocks if
+ * LIT_BUFSIZE is not greater than 32K.)
+ * - if compression is not successful for a file smaller than 64K, we can
+ * even emit a stored file instead of a stored block (saving 5 bytes).
+ * - creating new Huffman trees less frequently may not provide fast
+ * adaptation to changes in the input data statistics. (Take for
+ * example a binary file with poorly compressible code followed by
+ * a highly compressible string table.) Smaller buffer sizes give
+ * fast adaptation but have of course the overhead of transmitting trees
+ * more frequently.
+ * - I can't count above 4
+ * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
+ * memory at the expense of compression). Some optimizations would be possible
+ * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
+ */
+#if LIT_BUFSIZE > INBUFSIZ
+ error cannot overlay l_buf and inbuf
+#endif
+
+#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 data
+ */
+
+/* Data structure describing a single value and its code string. */
+typedef struct ct_data {
+ union {
+ ush freq; /* frequency count */
+ ush code; /* bit string */
+ } fc;
+ union {
+ ush dad; /* father node in Huffman tree */
+ ush len; /* length of bit string */
+ } dl;
+} ct_data;
+
+#define Freq fc.freq
+#define Code fc.code
+#define Dad dl.dad
+#define Len dl.len
+
+#define HEAP_SIZE (2*L_CODES+1)
+/* maximum heap size */
+
+local ct_data near dyn_ltree[HEAP_SIZE]; /* literal and length tree */
+local ct_data near dyn_dtree[2*D_CODES+1]; /* distance tree */
+
+local ct_data near 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 ct_init
+ * below).
+ */
+
+local ct_data near static_dtree[D_CODES];
+/* The static distance tree. (Actually a trivial tree since all codes use
+ * 5 bits.)
+ */
+
+local ct_data near bl_tree[2*BL_CODES+1];
+/* Huffman tree for the bit lengths */
+
+typedef struct tree_desc {
+ ct_data near *dyn_tree; /* the dynamic tree */
+ ct_data near *static_tree; /* corresponding static tree or NULL */
+ int near *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 */
+ int max_code; /* largest code with non zero frequency */
+} tree_desc;
+
+local tree_desc near l_desc =
+{dyn_ltree, static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS, 0};
+
+local tree_desc near d_desc =
+{dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0};
+
+local tree_desc near bl_desc =
+{bl_tree, (ct_data near *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS, 0};
+
+
+local ush near bl_count[MAX_BITS+1];
+/* number of codes at each bit length for an optimal tree */
+
+local uch near 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.
+ */
+
+local int near heap[2*L_CODES+1]; /* heap used to build the Huffman trees */
+local int heap_len; /* number of elements in the heap */
+local int heap_max; /* element of largest frequency */
+/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
+ * The same heap array is used to build all trees.
+ */
+
+local uch near depth[2*L_CODES+1];
+/* Depth of each subtree used as tie breaker for trees of equal frequency */
+
+local uch length_code[MAX_MATCH-MIN_MATCH+1];
+/* length code for each normalized match length (0 == MIN_MATCH) */
+
+local uch dist_code[512];
+/* 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.
+ */
+
+local int near base_length[LENGTH_CODES];
+/* First normalized length for each code (0 = MIN_MATCH) */
+
+local int near base_dist[D_CODES];
+/* First normalized distance for each code (0 = distance of 1) */
+
+#define l_buf inbuf
+/* DECLARE(uch, l_buf, LIT_BUFSIZE); buffer for literals or lengths */
+
+/* DECLARE(ush, d_buf, DIST_BUFSIZE); buffer for distances */
+
+local uch near flag_buf[(LIT_BUFSIZE/8)];
+/* flag_buf is a bit array distinguishing literals from lengths in
+ * l_buf, thus indicating the presence or absence of a distance.
+ */
+
+local unsigned last_lit; /* running index in l_buf */
+local unsigned last_dist; /* running index in d_buf */
+local unsigned last_flags; /* running index in flag_buf */
+local uch flags; /* current flags not yet saved in flag_buf */
+local uch flag_bit; /* current bit used in flags */
+/* bits are filled in flags starting at bit 0 (least significant).
+ * Note: these flags are overkill in the current code since we don't
+ * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
+ */
+
+local ulg opt_len; /* bit length of current block with optimal trees */
+local ulg static_len; /* bit length of current block with static trees */
+
+local ulg compressed_len; /* total bit length of compressed file */
+
+local ulg input_len; /* total byte length of input file */
+/* input_len is for debugging only since we can get it by other means. */
+
+ush *file_type; /* pointer to UNKNOWN, BINARY or ASCII */
+int *file_method; /* pointer to DEFLATE or STORE */
+
+#ifdef DEBUG
+extern ulg bits_sent; /* bit length of the compressed data */
+extern long isize; /* byte length of input file */
+#endif
+
+extern long block_start; /* window offset of current block */
+extern unsigned near strstart; /* window offset of current string */
+
+/* ===========================================================================
+ * Local (static) routines in this file.
+ */
+
+local void init_block OF((void));
+local void pqdownheap OF((ct_data near *tree, int k));
+local void gen_bitlen OF((tree_desc near *desc));
+local void gen_codes OF((ct_data near *tree, int max_code));
+local void build_tree OF((tree_desc near *desc));
+local void scan_tree OF((ct_data near *tree, int max_code));
+local void send_tree OF((ct_data near *tree, int max_code));
+local int build_bl_tree OF((void));
+local void send_all_trees OF((int lcodes, int dcodes, int blcodes));
+local void compress_block OF((ct_data near *ltree, ct_data near *dtree));
+local void set_file_type OF((void));
+
+
+#ifndef DEBUG
+# define send_code(c, tree) send_bits(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(c, tree) \
+ { if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \
+ send_bits(tree[c].Code, tree[c].Len); }
+#endif
+
+#define d_code(dist) \
+ ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)])
+/* Mapping from a distance to a distance code. dist is the distance - 1 and
+ * must not have side effects. dist_code[256] and dist_code[257] are never
+ * used.
+ */
+
+#define MAX(a,b) (a >= b ? a : b)
+/* the arguments must not have side effects */
+
+/* ===========================================================================
+ * Allocate the match buffer, initialize the various tables and save the
+ * location of the internal file attribute (ascii/binary) and method
+ * (DEFLATE/STORE).
+ */
+void ct_init(attr, methodp)
+ ush *attr; /* pointer to internal file attribute */
+ int *methodp; /* pointer to compression method */
+{
+ int n; /* iterates over tree elements */
+ int bits; /* bit counter */
+ int length; /* length value */
+ int code; /* code value */
+ int dist; /* distance index */
+
+ file_type = attr;
+ file_method = methodp;
+ compressed_len = input_len = 0L;
+
+ if (static_dtree[0].Len != 0) return; /* ct_init already called */
+
+ /* 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, "ct_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, "ct_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, "ct_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 near *)static_ltree, L_CODES+1);
+
+ /* The static distance tree is trivial: */
+ for (n = 0; n < D_CODES; n++) {
+ static_dtree[n].Len = 5;
+ static_dtree[n].Code = bi_reverse(n, 5);
+ }
+
+ /* Initialize the first block of the first file: */
+ init_block();
+}
+
+/* ===========================================================================
+ * Initialize a new block.
+ */
+local void init_block()
+{
+ int n; /* iterates over tree elements */
+
+ /* Initialize the trees. */
+ for (n = 0; n < L_CODES; n++) dyn_ltree[n].Freq = 0;
+ for (n = 0; n < D_CODES; n++) dyn_dtree[n].Freq = 0;
+ for (n = 0; n < BL_CODES; n++) bl_tree[n].Freq = 0;
+
+ dyn_ltree[END_BLOCK].Freq = 1;
+ opt_len = static_len = 0L;
+ last_lit = last_dist = last_flags = 0;
+ flags = 0; flag_bit = 1;
+}
+
+#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(tree, top) \
+{\
+ top = heap[SMALLEST]; \
+ heap[SMALLEST] = heap[heap_len--]; \
+ pqdownheap(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) \
+ (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(tree, k)
+ ct_data near *tree; /* the tree to restore */
+ int k; /* node to move down */
+{
+ int v = heap[k];
+ int j = k << 1; /* left son of k */
+ while (j <= heap_len) {
+ /* Set j to the smallest of the two sons: */
+ if (j < heap_len && smaller(tree, heap[j+1], heap[j])) j++;
+
+ /* Exit if v is smaller than both sons */
+ if (smaller(tree, v, heap[j])) break;
+
+ /* Exchange v with the smallest son */
+ heap[k] = heap[j]; k = j;
+
+ /* And continue down the tree, setting j to the left son of k */
+ j <<= 1;
+ }
+ 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(desc)
+ tree_desc near *desc; /* the tree descriptor */
+{
+ ct_data near *tree = desc->dyn_tree;
+ int near *extra = desc->extra_bits;
+ int base = desc->extra_base;
+ int max_code = desc->max_code;
+ int max_length = desc->max_length;
+ ct_data near *stree = desc->static_tree;
+ 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++) 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[heap[heap_max]].Len = 0; /* root of the heap */
+
+ for (h = heap_max+1; h < HEAP_SIZE; h++) {
+ n = 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 */
+
+ bl_count[bits]++;
+ xbits = 0;
+ if (n >= base) xbits = extra[n-base];
+ f = tree[n].Freq;
+ opt_len += (ulg)f * (bits + xbits);
+ if (stree) 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 (bl_count[bits] == 0) bits--;
+ bl_count[bits]--; /* move one leaf down the tree */
+ bl_count[bits+1] += 2; /* move one overflow item as its brother */
+ 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 = bl_count[bits];
+ while (n != 0) {
+ m = heap[--h];
+ if (m > max_code) continue;
+ if (tree[m].Len != (unsigned) bits) {
+ Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
+ 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)
+ ct_data near *tree; /* the tree to decorate */
+ int max_code; /* largest code with non zero frequency */
+{
+ 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);
+
+ Tracec(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(desc)
+ tree_desc near *desc; /* the tree descriptor */
+{
+ ct_data near *tree = desc->dyn_tree;
+ ct_data near *stree = desc->static_tree;
+ int elems = desc->elems;
+ int n, m; /* iterate over heap elements */
+ int max_code = -1; /* largest code with non zero frequency */
+ int node = elems; /* next internal node of the tree */
+
+ /* 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.
+ */
+ heap_len = 0, heap_max = HEAP_SIZE;
+
+ for (n = 0; n < elems; n++) {
+ if (tree[n].Freq != 0) {
+ heap[++heap_len] = max_code = n;
+ 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 (heap_len < 2) {
+ int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0);
+ tree[new].Freq = 1;
+ depth[new] = 0;
+ opt_len--; if (stree) static_len -= stree[new].Len;
+ /* new 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 = heap_len/2; n >= 1; n--) pqdownheap(tree, n);
+
+ /* Construct the Huffman tree by repeatedly combining the least two
+ * frequent nodes.
+ */
+ do {
+ pqremove(tree, n); /* n = node of least frequency */
+ m = heap[SMALLEST]; /* m = node of next least frequency */
+
+ heap[--heap_max] = n; /* keep the nodes sorted by frequency */
+ heap[--heap_max] = m;
+
+ /* Create a new node father of n and m */
+ tree[node].Freq = tree[n].Freq + tree[m].Freq;
+ depth[node] = (uch) (MAX(depth[n], depth[m]) + 1);
+ tree[n].Dad = tree[m].Dad = (ush)node;
+#ifdef DUMP_BL_TREE
+ if (tree == 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 */
+ heap[SMALLEST] = node++;
+ pqdownheap(tree, SMALLEST);
+
+ } while (heap_len >= 2);
+
+ heap[--heap_max] = heap[SMALLEST];
+
+ /* At this point, the fields freq and dad are set. We can now
+ * generate the bit lengths.
+ */
+ gen_bitlen((tree_desc near *)desc);
+
+ /* The field len is now set, we can generate the bit codes */
+ gen_codes ((ct_data near *)tree, max_code);
+}
+
+/* ===========================================================================
+ * Scan a literal or distance tree to determine the frequencies of the codes
+ * in the bit length tree. Updates opt_len to take into account the repeat
+ * counts. (The contribution of the bit length codes will be added later
+ * during the construction of bl_tree.)
+ */
+local void scan_tree (tree, max_code)
+ ct_data near *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) {
+ bl_tree[curlen].Freq += count;
+ } else if (curlen != 0) {
+ if (curlen != prevlen) bl_tree[curlen].Freq++;
+ bl_tree[REP_3_6].Freq++;
+ } else if (count <= 10) {
+ bl_tree[REPZ_3_10].Freq++;
+ } else {
+ 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 (tree, max_code)
+ ct_data near *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(curlen, bl_tree); } while (--count != 0);
+
+ } else if (curlen != 0) {
+ if (curlen != prevlen) {
+ send_code(curlen, bl_tree); count--;
+ }
+ Assert(count >= 3 && count <= 6, " 3_6?");
+ send_code(REP_3_6, bl_tree); send_bits(count-3, 2);
+
+ } else if (count <= 10) {
+ send_code(REPZ_3_10, bl_tree); send_bits(count-3, 3);
+
+ } else {
+ send_code(REPZ_11_138, bl_tree); send_bits(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()
+{
+ 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((ct_data near *)dyn_ltree, l_desc.max_code);
+ scan_tree((ct_data near *)dyn_dtree, d_desc.max_code);
+
+ /* Build the bit length tree: */
+ build_tree((tree_desc near *)(&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 (bl_tree[bl_order[max_blindex]].Len != 0) break;
+ }
+ /* Update opt_len to include the bit length tree and counts */
+ opt_len += 3*(max_blindex+1) + 5+5+4;
+ Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, 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(lcodes, dcodes, blcodes)
+ 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(lcodes-257, 5); /* not +255 as stated in appnote.txt */
+ send_bits(dcodes-1, 5);
+ send_bits(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(bl_tree[bl_order[rank]].Len, 3);
+ }
+ Tracev((stderr, "\nbl tree: sent %ld", bits_sent));
+
+ send_tree((ct_data near *)dyn_ltree, lcodes-1); /* send the literal tree */
+ Tracev((stderr, "\nlit tree: sent %ld", bits_sent));
+
+ send_tree((ct_data near *)dyn_dtree, dcodes-1); /* send the distance tree */
+ Tracev((stderr, "\ndist tree: sent %ld", bits_sent));
+}
+
+/* ===========================================================================
+ * Determine the best encoding for the current block: dynamic trees, static
+ * trees or store, and output the encoded block to the zip file. This function
+ * returns the total compressed length for the file so far.
+ */
+ulg flush_block(buf, stored_len, eof)
+ char *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; /* index of last bit length code of non zero freq */
+
+ flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */
+
+ /* Check if the file is ascii or binary */
+ if (*file_type == (ush)UNKNOWN) set_file_type();
+
+ /* Construct the literal and distance trees */
+ build_tree((tree_desc near *)(&l_desc));
+ Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len));
+
+ build_tree((tree_desc near *)(&d_desc));
+ Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, 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();
+
+ /* Determine the best encoding. Compute first the block length in bytes */
+ opt_lenb = (opt_len+3+7)>>3;
+ static_lenb = (static_len+3+7)>>3;
+ input_len += stored_len; /* for debugging only */
+
+ Trace((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
+ opt_lenb, opt_len, static_lenb, static_len, stored_len,
+ last_lit, last_dist));
+
+ if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
+
+ /* If compression failed and this is the first and last block,
+ * and if the zip file can be seeked (to rewrite the local header),
+ * the whole file is transformed into a stored file:
+ */
+#ifdef FORCE_METHOD
+ if (level == 1 && eof && compressed_len == 0L) { /* force stored file */
+#else
+ if (stored_len <= opt_lenb && eof && compressed_len == 0L && seekable()) {
+#endif
+ /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
+ if (buf == (char*)0) error ("block vanished");
+
+ copy_block(buf, (unsigned)stored_len, 0); /* without header */
+ compressed_len = stored_len << 3;
+ *file_method = STORED;
+
+#ifdef FORCE_METHOD
+ } else if (level == 2 && buf != (char*)0) { /* force stored block */
+#else
+ } 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.
+ */
+ send_bits((STORED_BLOCK<<1)+eof, 3); /* send block type */
+ compressed_len = (compressed_len + 3 + 7) & ~7L;
+ compressed_len += (stored_len + 4) << 3;
+
+ copy_block(buf, (unsigned)stored_len, 1); /* with header */
+
+#ifdef FORCE_METHOD
+ } else if (level == 3) { /* force static trees */
+#else
+ } else if (static_lenb == opt_lenb) {
+#endif
+ send_bits((STATIC_TREES<<1)+eof, 3);
+ compress_block((ct_data near *)static_ltree, (ct_data near *)static_dtree);
+ compressed_len += 3 + static_len;
+ } else {
+ send_bits((DYN_TREES<<1)+eof, 3);
+ send_all_trees(l_desc.max_code+1, d_desc.max_code+1, max_blindex+1);
+ compress_block((ct_data near *)dyn_ltree, (ct_data near *)dyn_dtree);
+ compressed_len += 3 + opt_len;
+ }
+ Assert (compressed_len == bits_sent, "bad compressed size");
+ init_block();
+
+ if (eof) {
+ Assert (input_len == isize, "bad input size");
+ bi_windup();
+ compressed_len += 7; /* align on byte boundary */
+ }
+ Tracev((stderr,"\ncomprlen %lu(%lu) ", compressed_len>>3,
+ compressed_len-7*eof));
+
+ return compressed_len >> 3;
+}
+
+/* ===========================================================================
+ * Save the match info and tally the frequency counts. Return true if
+ * the current block must be flushed.
+ */
+int ct_tally (dist, lc)
+ int dist; /* distance of matched string */
+ int lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
+{
+ l_buf[last_lit++] = (uch)lc;
+ if (dist == 0) {
+ /* lc is the unmatched char */
+ dyn_ltree[lc].Freq++;
+ } else {
+ /* Here, lc is the match length - MIN_MATCH */
+ dist--; /* dist = match distance - 1 */
+ Assert((ush)dist < (ush)MAX_DIST &&
+ (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
+ (ush)d_code(dist) < (ush)D_CODES, "ct_tally: bad match");
+
+ dyn_ltree[length_code[lc]+LITERALS+1].Freq++;
+ dyn_dtree[d_code(dist)].Freq++;
+
+ d_buf[last_dist++] = (ush)dist;
+ flags |= flag_bit;
+ }
+ flag_bit <<= 1;
+
+ /* Output the flags if they fill a byte: */
+ if ((last_lit & 7) == 0) {
+ flag_buf[last_flags++] = flags;
+ flags = 0, flag_bit = 1;
+ }
+ /* Try to guess if it is profitable to stop the current block here */
+ if (level > 2 && (last_lit & 0xfff) == 0) {
+ /* Compute an upper bound for the compressed length */
+ ulg out_length = (ulg)last_lit*8L;
+ ulg in_length = (ulg)strstart-block_start;
+ int dcode;
+ for (dcode = 0; dcode < D_CODES; dcode++) {
+ out_length += (ulg)dyn_dtree[dcode].Freq*(5L+extra_dbits[dcode]);
+ }
+ out_length >>= 3;
+ Trace((stderr,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
+ last_lit, last_dist, in_length, out_length,
+ 100L - out_length*100L/in_length));
+ if (last_dist < last_lit/2 && out_length < in_length/2) return 1;
+ }
+ return (last_lit == LIT_BUFSIZE-1 || last_dist == DIST_BUFSIZE);
+ /* 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(ltree, dtree)
+ ct_data near *ltree; /* literal tree */
+ ct_data near *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 dx = 0; /* running index in d_buf */
+ unsigned fx = 0; /* running index in flag_buf */
+ uch flag = 0; /* current flags */
+ unsigned code; /* the code to send */
+ int extra; /* number of extra bits to send */
+
+ if (last_lit != 0) do {
+ if ((lx & 7) == 0) flag = flag_buf[fx++];
+ lc = l_buf[lx++];
+ if ((flag & 1) == 0) {
+ send_code(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(code+LITERALS+1, ltree); /* send the length code */
+ extra = extra_lbits[code];
+ if (extra != 0) {
+ lc -= base_length[code];
+ send_bits(lc, extra); /* send the extra length bits */
+ }
+ dist = d_buf[dx++];
+ /* Here, dist is the match distance - 1 */
+ code = d_code(dist);
+ Assert (code < D_CODES, "bad d_code");
+
+ send_code(code, dtree); /* send the distance code */
+ extra = extra_dbits[code];
+ if (extra != 0) {
+ dist -= base_dist[code];
+ send_bits(dist, extra); /* send the extra distance bits */
+ }
+ } /* literal or match pair ? */
+ flag >>= 1;
+ } while (lx < last_lit);
+
+ send_code(END_BLOCK, ltree);
+}
+
+/* ===========================================================================
+ * Set the file type to ASCII or BINARY, using a crude approximation:
+ * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
+ * IN assertion: the fields freq of dyn_ltree are set and the total of all
+ * frequencies does not exceed 64K (to fit in an int on 16 bit machines).
+ */
+local void set_file_type()
+{
+ int n = 0;
+ unsigned ascii_freq = 0;
+ unsigned bin_freq = 0;
+ while (n < 7) bin_freq += dyn_ltree[n++].Freq;
+ while (n < 128) ascii_freq += dyn_ltree[n++].Freq;
+ while (n < LITERALS) bin_freq += dyn_ltree[n++].Freq;
+ *file_type = bin_freq > (ascii_freq >> 2) ? BINARY : ASCII;
+ if (*file_type == BINARY && translate_eol) {
+ warn("-l used on binary file", "");
+ }
+}
projects / unix-history / commitdiff