| /* trees.c -- output deflated data using Huffman coding |
| * Copyright (C) 1995-2021 Jean-loup Gailly |
| * detect_data_type() function provided freely by Cosmin Truta, 2006 |
| * 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 ZLIB_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. |
| */ |
| |
| /* =========================================================================== |
| * 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 */ |
| }; |
| |
| #ifdef NO_INIT_GLOBAL_POINTERS |
| # define TCONST |
| #else |
| # define TCONST const |
| #endif |
| |
| local TCONST static_tree_desc static_l_desc = |
| {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; |
| |
| local TCONST static_tree_desc static_d_desc = |
| {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; |
| |
| local TCONST static_tree_desc static_bl_desc = |
| {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; |
| |
| /* =========================================================================== |
| * 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)); \ |
| } |
| |
| /* =========================================================================== |
| * 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(unsigned code, int len) { |
| 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(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(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 ZLIB_DEBUG |
| s->bits_sent = (s->bits_sent + 7) & ~7; |
| #endif |
| } |
| |
| /* =========================================================================== |
| * 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(ct_data *tree, int max_code, ushf *bl_count) { |
| ush next_code[MAX_BITS+1]; /* next code value for each bit length */ |
| unsigned 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++) { |
| code = (code + bl_count[bits - 1]) << 1; |
| next_code[bits] = (ush)code; |
| } |
| /* 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 = (ush)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)); |
| } |
| } |
| |
| #ifdef GEN_TREES_H |
| local void gen_trees_header(void); |
| #endif |
| |
| #ifndef ZLIB_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 /* !ZLIB_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 |
| |
| /* =========================================================================== |
| * Send a value on a given number of bits. |
| * IN assertion: length <= 16 and value fits in length bits. |
| */ |
| #ifdef ZLIB_DEBUG |
| local void send_bits(deflate_state *s, int value, int length) { |
| 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 |= (ush)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 |= (ush)value << s->bi_valid; |
| s->bi_valid += length; |
| } |
| } |
| #else /* !ZLIB_DEBUG */ |
| |
| #define send_bits(s, value, length) \ |
| { int len = length;\ |
| if (s->bi_valid > (int)Buf_size - len) {\ |
| int val = (int)value;\ |
| s->bi_buf |= (ush)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 |= (ush)(value) << s->bi_valid;\ |
| s->bi_valid += len;\ |
| }\ |
| } |
| #endif /* ZLIB_DEBUG */ |
| |
| |
| /* the arguments must not have side effects */ |
| |
| /* =========================================================================== |
| * Initialize the various 'constant' tables. |
| */ |
| local void tr_static_init(void) { |
| #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: */ |
| #ifdef NO_INIT_GLOBAL_POINTERS |
| 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; |
| #endif |
| |
| /* 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) */ |
| } |
| |
| /* =========================================================================== |
| * Generate the file trees.h describing the static trees. |
| */ |
| #ifdef GEN_TREES_H |
| # ifndef ZLIB_DEBUG |
| # include <stdio.h> |
| # endif |
| |
| # define SEPARATOR(i, last, width) \ |
| ((i) == (last)? "\n};\n\n" : \ |
| ((i) % (width) == (width) - 1 ? ",\n" : ", ")) |
| |
| void gen_trees_header(void) { |
| 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 ZLIB_INTERNAL _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 ZLIB_INTERNAL _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 a new block. |
| */ |
| local void init_block(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->sym_next = s->matches = 0; |
| } |
| |
| /* =========================================================================== |
| * Initialize the tree data structures for a new zlib stream. |
| */ |
| void ZLIB_INTERNAL _tr_init(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; |
| #ifdef ZLIB_DEBUG |
| s->compressed_len = 0L; |
| s->bits_sent = 0L; |
| #endif |
| |
| /* Initialize the first block of the first file: */ |
| init_block(s); |
| } |
| |
| #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(deflate_state *s, ct_data *tree, int k) { |
| 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(deflate_state *s, tree_desc *desc) { |
| 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 * (unsigned)(bits + xbits); |
| if (stree) s->static_len += (ulg)f * (unsigned)(stree[n].Len + xbits); |
| } |
| if (overflow == 0) return; |
| |
| Tracev((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) { |
| Tracev((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); |
| s->opt_len += ((ulg)bits - tree[m].Len) * tree[m].Freq; |
| tree[m].Len = (ush)bits; |
| } |
| n--; |
| } |
| } |
| } |
| |
| #ifdef DUMP_BL_TREE |
| # include <stdio.h> |
| #endif |
| |
| /* =========================================================================== |
| * 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(deflate_state *s, tree_desc *desc) { |
| 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(deflate_state *s, ct_data *tree, int max_code) { |
| 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(deflate_state *s, ct_data *tree, int max_code) { |
| 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(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*((ulg)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(deflate_state *s, int lcodes, int dcodes, |
| int blcodes) { |
| 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 ZLIB_INTERNAL _tr_stored_block(deflate_state *s, charf *buf, |
| ulg stored_len, int last) { |
| send_bits(s, (STORED_BLOCK<<1) + last, 3); /* send block type */ |
| bi_windup(s); /* align on byte boundary */ |
| put_short(s, (ush)stored_len); |
| put_short(s, (ush)~stored_len); |
| if (stored_len) |
| zmemcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len); |
| s->pending += stored_len; |
| #ifdef ZLIB_DEBUG |
| s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L; |
| s->compressed_len += (stored_len + 4) << 3; |
| s->bits_sent += 2*16; |
| s->bits_sent += stored_len << 3; |
| #endif |
| } |
| |
| /* =========================================================================== |
| * Flush the bits in the bit buffer to pending output (leaves at most 7 bits) |
| */ |
| void ZLIB_INTERNAL _tr_flush_bits(deflate_state *s) { |
| bi_flush(s); |
| } |
| |
| /* =========================================================================== |
| * Send one empty static block to give enough lookahead for inflate. |
| * This takes 10 bits, of which 7 may remain in the bit buffer. |
| */ |
| void ZLIB_INTERNAL _tr_align(deflate_state *s) { |
| send_bits(s, STATIC_TREES<<1, 3); |
| send_code(s, END_BLOCK, static_ltree); |
| #ifdef ZLIB_DEBUG |
| s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ |
| #endif |
| bi_flush(s); |
| } |
| |
| /* =========================================================================== |
| * Send the block data compressed using the given Huffman trees |
| */ |
| local void compress_block(deflate_state *s, const ct_data *ltree, |
| const ct_data *dtree) { |
| unsigned dist; /* distance of matched string */ |
| int lc; /* match length or unmatched char (if dist == 0) */ |
| unsigned sx = 0; /* running index in sym_buf */ |
| unsigned code; /* the code to send */ |
| int extra; /* number of extra bits to send */ |
| |
| if (s->sym_next != 0) do { |
| dist = s->sym_buf[sx++] & 0xff; |
| dist += (unsigned)(s->sym_buf[sx++] & 0xff) << 8; |
| lc = s->sym_buf[sx++]; |
| 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 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 -= (unsigned)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 sym_buf is ok: */ |
| Assert(s->pending < s->lit_bufsize + sx, "pendingBuf overflow"); |
| |
| } while (sx < s->sym_next); |
| |
| send_code(s, END_BLOCK, ltree); |
| } |
| |
| /* =========================================================================== |
| * Check if the data type is TEXT or BINARY, using the following algorithm: |
| * - TEXT if the two conditions below are satisfied: |
| * a) There are no non-portable control characters belonging to the |
| * "block list" (0..6, 14..25, 28..31). |
| * b) There is at least one printable character belonging to the |
| * "allow list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255). |
| * - BINARY otherwise. |
| * - The following partially-portable control characters form a |
| * "gray list" that is ignored in this detection algorithm: |
| * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}). |
| * IN assertion: the fields Freq of dyn_ltree are set. |
| */ |
| local int detect_data_type(deflate_state *s) { |
| /* block_mask is the bit mask of block-listed bytes |
| * set bits 0..6, 14..25, and 28..31 |
| * 0xf3ffc07f = binary 11110011111111111100000001111111 |
| */ |
| unsigned long block_mask = 0xf3ffc07fUL; |
| int n; |
| |
| /* Check for non-textual ("block-listed") bytes. */ |
| for (n = 0; n <= 31; n++, block_mask >>= 1) |
| if ((block_mask & 1) && (s->dyn_ltree[n].Freq != 0)) |
| return Z_BINARY; |
| |
| /* Check for textual ("allow-listed") bytes. */ |
| if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0 |
| || s->dyn_ltree[13].Freq != 0) |
| return Z_TEXT; |
| for (n = 32; n < LITERALS; n++) |
| if (s->dyn_ltree[n].Freq != 0) |
| return Z_TEXT; |
| |
| /* There are no "block-listed" or "allow-listed" bytes: |
| * this stream either is empty or has tolerated ("gray-listed") bytes only. |
| */ |
| return Z_BINARY; |
| } |
| |
| /* =========================================================================== |
| * Determine the best encoding for the current block: dynamic trees, static |
| * trees or store, and write out the encoded block. |
| */ |
| void ZLIB_INTERNAL _tr_flush_block(deflate_state *s, charf *buf, |
| ulg stored_len, int last) { |
| 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 (s->strm->data_type == Z_UNKNOWN) |
| s->strm->data_type = detect_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->sym_next / 3)); |
| |
| #ifndef FORCE_STATIC |
| if (static_lenb <= opt_lenb || s->strategy == Z_FIXED) |
| #endif |
| 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, last); |
| |
| } else if (static_lenb == opt_lenb) { |
| send_bits(s, (STATIC_TREES<<1) + last, 3); |
| compress_block(s, (const ct_data *)static_ltree, |
| (const ct_data *)static_dtree); |
| #ifdef ZLIB_DEBUG |
| s->compressed_len += 3 + s->static_len; |
| #endif |
| } else { |
| send_bits(s, (DYN_TREES<<1) + last, 3); |
| send_all_trees(s, s->l_desc.max_code + 1, s->d_desc.max_code + 1, |
| max_blindex + 1); |
| compress_block(s, (const ct_data *)s->dyn_ltree, |
| (const ct_data *)s->dyn_dtree); |
| #ifdef ZLIB_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 (last) { |
| bi_windup(s); |
| #ifdef ZLIB_DEBUG |
| s->compressed_len += 7; /* align on byte boundary */ |
| #endif |
| } |
| Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len >> 3, |
| s->compressed_len - 7*last)); |
| } |
| |
| /* =========================================================================== |
| * Save the match info and tally the frequency counts. Return true if |
| * the current block must be flushed. |
| */ |
| int ZLIB_INTERNAL _tr_tally(deflate_state *s, unsigned dist, unsigned lc) { |
| s->sym_buf[s->sym_next++] = (uch)dist; |
| s->sym_buf[s->sym_next++] = (uch)(dist >> 8); |
| s->sym_buf[s->sym_next++] = (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++; |
| } |
| return (s->sym_next == s->sym_end); |
| } |
