trees.c revision 206924
117651Speter/* trees.c -- output deflated data using Huffman coding 2206924Sdelphij * Copyright (C) 1995-2010 Jean-loup Gailly 3205471Sdelphij * detect_data_type() function provided freely by Cosmin Truta, 2006 4131380Stjr * For conditions of distribution and use, see copyright notice in zlib.h 517651Speter */ 617651Speter 717651Speter/* 817651Speter * ALGORITHM 917651Speter * 1017651Speter * The "deflation" process uses several Huffman trees. The more 1117651Speter * common source values are represented by shorter bit sequences. 1217651Speter * 1317651Speter * Each code tree is stored in a compressed form which is itself 1417651Speter * a Huffman encoding of the lengths of all the code strings (in 1517651Speter * ascending order by source values). The actual code strings are 1617651Speter * reconstructed from the lengths in the inflate process, as described 1717651Speter * in the deflate specification. 1817651Speter * 1917651Speter * REFERENCES 2017651Speter * 2117651Speter * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification". 2217651Speter * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc 2317651Speter * 2417651Speter * Storer, James A. 2517651Speter * Data Compression: Methods and Theory, pp. 49-50. 2617651Speter * Computer Science Press, 1988. ISBN 0-7167-8156-5. 2717651Speter * 2817651Speter * Sedgewick, R. 2917651Speter * Algorithms, p290. 3017651Speter * Addison-Wesley, 1983. ISBN 0-201-06672-6. 3117651Speter */ 3217651Speter 33146081Skientzle/* @(#) $Id$ */ 3417651Speter 3533908Ssteve/* #define GEN_TREES_H */ 3633908Ssteve 3717651Speter#include "deflate.h" 3817651Speter 3917651Speter#ifdef DEBUG 4017651Speter# include <ctype.h> 4117651Speter#endif 4217651Speter 4317651Speter/* =========================================================================== 4417651Speter * Constants 4517651Speter */ 4617651Speter 4717651Speter#define MAX_BL_BITS 7 4817651Speter/* Bit length codes must not exceed MAX_BL_BITS bits */ 4917651Speter 5017651Speter#define END_BLOCK 256 5117651Speter/* end of block literal code */ 5217651Speter 5317651Speter#define REP_3_6 16 5417651Speter/* repeat previous bit length 3-6 times (2 bits of repeat count) */ 5517651Speter 5617651Speter#define REPZ_3_10 17 5717651Speter/* repeat a zero length 3-10 times (3 bits of repeat count) */ 5817651Speter 5917651Speter#define REPZ_11_138 18 6017651Speter/* repeat a zero length 11-138 times (7 bits of repeat count) */ 6117651Speter 6233908Sstevelocal const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ 6317651Speter = {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}; 6417651Speter 6533908Sstevelocal const int extra_dbits[D_CODES] /* extra bits for each distance code */ 6617651Speter = {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}; 6717651Speter 6833908Sstevelocal const int extra_blbits[BL_CODES]/* extra bits for each bit length code */ 6917651Speter = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; 7017651Speter 7133908Sstevelocal const uch bl_order[BL_CODES] 7217651Speter = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; 7317651Speter/* The lengths of the bit length codes are sent in order of decreasing 7417651Speter * probability, to avoid transmitting the lengths for unused bit length codes. 7517651Speter */ 7617651Speter 7717651Speter#define Buf_size (8 * 2*sizeof(char)) 7817651Speter/* Number of bits used within bi_buf. (bi_buf might be implemented on 7917651Speter * more than 16 bits on some systems.) 8017651Speter */ 8117651Speter 8217651Speter/* =========================================================================== 8317651Speter * Local data. These are initialized only once. 8417651Speter */ 8517651Speter 8633908Ssteve#define DIST_CODE_LEN 512 /* see definition of array dist_code below */ 8733908Ssteve 8833908Ssteve#if defined(GEN_TREES_H) || !defined(STDC) 8933908Ssteve/* non ANSI compilers may not accept trees.h */ 9033908Ssteve 9117651Speterlocal ct_data static_ltree[L_CODES+2]; 9217651Speter/* The static literal tree. Since the bit lengths are imposed, there is no 9317651Speter * need for the L_CODES extra codes used during heap construction. However 9417651Speter * The codes 286 and 287 are needed to build a canonical tree (see _tr_init 9517651Speter * below). 9617651Speter */ 9717651Speter 9817651Speterlocal ct_data static_dtree[D_CODES]; 9917651Speter/* The static distance tree. (Actually a trivial tree since all codes use 10017651Speter * 5 bits.) 10117651Speter */ 10217651Speter 10333908Ssteveuch _dist_code[DIST_CODE_LEN]; 10433908Ssteve/* Distance codes. The first 256 values correspond to the distances 10517651Speter * 3 .. 258, the last 256 values correspond to the top 8 bits of 10617651Speter * the 15 bit distances. 10717651Speter */ 10817651Speter 10933908Ssteveuch _length_code[MAX_MATCH-MIN_MATCH+1]; 11017651Speter/* length code for each normalized match length (0 == MIN_MATCH) */ 11117651Speter 11217651Speterlocal int base_length[LENGTH_CODES]; 11317651Speter/* First normalized length for each code (0 = MIN_MATCH) */ 11417651Speter 11517651Speterlocal int base_dist[D_CODES]; 11617651Speter/* First normalized distance for each code (0 = distance of 1) */ 11717651Speter 11833908Ssteve#else 11933908Ssteve# include "trees.h" 12033908Ssteve#endif /* GEN_TREES_H */ 12133908Ssteve 12217651Speterstruct static_tree_desc_s { 12333908Ssteve const ct_data *static_tree; /* static tree or NULL */ 12433908Ssteve const intf *extra_bits; /* extra bits for each code or NULL */ 12517651Speter int extra_base; /* base index for extra_bits */ 12617651Speter int elems; /* max number of elements in the tree */ 12717651Speter int max_length; /* max bit length for the codes */ 12817651Speter}; 12917651Speter 13017651Speterlocal static_tree_desc static_l_desc = 13117651Speter{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; 13217651Speter 13317651Speterlocal static_tree_desc static_d_desc = 13417651Speter{static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; 13517651Speter 13617651Speterlocal static_tree_desc static_bl_desc = 13733908Ssteve{(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; 13817651Speter 13917651Speter/* =========================================================================== 14017651Speter * Local (static) routines in this file. 14117651Speter */ 14217651Speter 14317651Speterlocal void tr_static_init OF((void)); 14417651Speterlocal void init_block OF((deflate_state *s)); 14517651Speterlocal void pqdownheap OF((deflate_state *s, ct_data *tree, int k)); 14617651Speterlocal void gen_bitlen OF((deflate_state *s, tree_desc *desc)); 14717651Speterlocal void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count)); 14817651Speterlocal void build_tree OF((deflate_state *s, tree_desc *desc)); 14917651Speterlocal void scan_tree OF((deflate_state *s, ct_data *tree, int max_code)); 15017651Speterlocal void send_tree OF((deflate_state *s, ct_data *tree, int max_code)); 15117651Speterlocal int build_bl_tree OF((deflate_state *s)); 15217651Speterlocal void send_all_trees OF((deflate_state *s, int lcodes, int dcodes, 15317651Speter int blcodes)); 15417651Speterlocal void compress_block OF((deflate_state *s, ct_data *ltree, 15517651Speter ct_data *dtree)); 156205471Sdelphijlocal int detect_data_type OF((deflate_state *s)); 15717651Speterlocal unsigned bi_reverse OF((unsigned value, int length)); 15817651Speterlocal void bi_windup OF((deflate_state *s)); 15917651Speterlocal void bi_flush OF((deflate_state *s)); 16017651Speterlocal void copy_block OF((deflate_state *s, charf *buf, unsigned len, 16117651Speter int header)); 16217651Speter 16333908Ssteve#ifdef GEN_TREES_H 16433908Sstevelocal void gen_trees_header OF((void)); 16533908Ssteve#endif 16633908Ssteve 16717651Speter#ifndef DEBUG 16817651Speter# define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len) 16917651Speter /* Send a code of the given tree. c and tree must not have side effects */ 17017651Speter 17117651Speter#else /* DEBUG */ 17217651Speter# define send_code(s, c, tree) \ 17333908Ssteve { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \ 17417651Speter send_bits(s, tree[c].Code, tree[c].Len); } 17517651Speter#endif 17617651Speter 17717651Speter/* =========================================================================== 17817651Speter * Output a short LSB first on the stream. 17917651Speter * IN assertion: there is enough room in pendingBuf. 18017651Speter */ 18117651Speter#define put_short(s, w) { \ 18217651Speter put_byte(s, (uch)((w) & 0xff)); \ 18317651Speter put_byte(s, (uch)((ush)(w) >> 8)); \ 18417651Speter} 18517651Speter 18617651Speter/* =========================================================================== 18717651Speter * Send a value on a given number of bits. 18817651Speter * IN assertion: length <= 16 and value fits in length bits. 18917651Speter */ 19017651Speter#ifdef DEBUG 19117651Speterlocal void send_bits OF((deflate_state *s, int value, int length)); 19217651Speter 19317651Speterlocal void send_bits(s, value, length) 19417651Speter deflate_state *s; 19517651Speter int value; /* value to send */ 19617651Speter int length; /* number of bits */ 19717651Speter{ 19817651Speter Tracevv((stderr," l %2d v %4x ", length, value)); 19917651Speter Assert(length > 0 && length <= 15, "invalid length"); 20017651Speter s->bits_sent += (ulg)length; 20117651Speter 20217651Speter /* If not enough room in bi_buf, use (valid) bits from bi_buf and 20317651Speter * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid)) 20417651Speter * unused bits in value. 20517651Speter */ 20617651Speter if (s->bi_valid > (int)Buf_size - length) { 207205471Sdelphij s->bi_buf |= (ush)value << s->bi_valid; 20817651Speter put_short(s, s->bi_buf); 20917651Speter s->bi_buf = (ush)value >> (Buf_size - s->bi_valid); 21017651Speter s->bi_valid += length - Buf_size; 21117651Speter } else { 212205471Sdelphij s->bi_buf |= (ush)value << s->bi_valid; 21317651Speter s->bi_valid += length; 21417651Speter } 21517651Speter} 21617651Speter#else /* !DEBUG */ 21717651Speter 21817651Speter#define send_bits(s, value, length) \ 21917651Speter{ int len = length;\ 22017651Speter if (s->bi_valid > (int)Buf_size - len) {\ 22117651Speter int val = value;\ 222205471Sdelphij s->bi_buf |= (ush)val << s->bi_valid;\ 22317651Speter put_short(s, s->bi_buf);\ 22417651Speter s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\ 22517651Speter s->bi_valid += len - Buf_size;\ 22617651Speter } else {\ 227205471Sdelphij s->bi_buf |= (ush)(value) << s->bi_valid;\ 22817651Speter s->bi_valid += len;\ 22917651Speter }\ 23017651Speter} 23117651Speter#endif /* DEBUG */ 23217651Speter 23317651Speter 23417651Speter/* the arguments must not have side effects */ 23517651Speter 23617651Speter/* =========================================================================== 23733908Ssteve * Initialize the various 'constant' tables. 23817651Speter */ 23917651Speterlocal void tr_static_init() 24017651Speter{ 24133908Ssteve#if defined(GEN_TREES_H) || !defined(STDC) 24217651Speter static int static_init_done = 0; 24317651Speter int n; /* iterates over tree elements */ 24417651Speter int bits; /* bit counter */ 24517651Speter int length; /* length value */ 24617651Speter int code; /* code value */ 24717651Speter int dist; /* distance index */ 24817651Speter ush bl_count[MAX_BITS+1]; 24917651Speter /* number of codes at each bit length for an optimal tree */ 25017651Speter 25117651Speter if (static_init_done) return; 25217651Speter 25342471Speter /* For some embedded targets, global variables are not initialized: */ 254205471Sdelphij#ifdef NO_INIT_GLOBAL_POINTERS 25542471Speter static_l_desc.static_tree = static_ltree; 25642471Speter static_l_desc.extra_bits = extra_lbits; 25742471Speter static_d_desc.static_tree = static_dtree; 25842471Speter static_d_desc.extra_bits = extra_dbits; 25942471Speter static_bl_desc.extra_bits = extra_blbits; 260205471Sdelphij#endif 26142471Speter 26217651Speter /* Initialize the mapping length (0..255) -> length code (0..28) */ 26317651Speter length = 0; 26417651Speter for (code = 0; code < LENGTH_CODES-1; code++) { 26517651Speter base_length[code] = length; 26617651Speter for (n = 0; n < (1<<extra_lbits[code]); n++) { 26733908Ssteve _length_code[length++] = (uch)code; 26817651Speter } 26917651Speter } 27017651Speter Assert (length == 256, "tr_static_init: length != 256"); 27117651Speter /* Note that the length 255 (match length 258) can be represented 27217651Speter * in two different ways: code 284 + 5 bits or code 285, so we 27317651Speter * overwrite length_code[255] to use the best encoding: 27417651Speter */ 27533908Ssteve _length_code[length-1] = (uch)code; 27617651Speter 27717651Speter /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ 27817651Speter dist = 0; 27917651Speter for (code = 0 ; code < 16; code++) { 28017651Speter base_dist[code] = dist; 28117651Speter for (n = 0; n < (1<<extra_dbits[code]); n++) { 28233908Ssteve _dist_code[dist++] = (uch)code; 28317651Speter } 28417651Speter } 28517651Speter Assert (dist == 256, "tr_static_init: dist != 256"); 28617651Speter dist >>= 7; /* from now on, all distances are divided by 128 */ 28717651Speter for ( ; code < D_CODES; code++) { 28817651Speter base_dist[code] = dist << 7; 28917651Speter for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { 29033908Ssteve _dist_code[256 + dist++] = (uch)code; 29117651Speter } 29217651Speter } 29317651Speter Assert (dist == 256, "tr_static_init: 256+dist != 512"); 29417651Speter 29517651Speter /* Construct the codes of the static literal tree */ 29617651Speter for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; 29717651Speter n = 0; 29817651Speter while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; 29917651Speter while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; 30017651Speter while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; 30117651Speter while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; 30217651Speter /* Codes 286 and 287 do not exist, but we must include them in the 30317651Speter * tree construction to get a canonical Huffman tree (longest code 30417651Speter * all ones) 30517651Speter */ 30617651Speter gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count); 30717651Speter 30817651Speter /* The static distance tree is trivial: */ 30917651Speter for (n = 0; n < D_CODES; n++) { 31017651Speter static_dtree[n].Len = 5; 31117651Speter static_dtree[n].Code = bi_reverse((unsigned)n, 5); 31217651Speter } 31317651Speter static_init_done = 1; 31433908Ssteve 31533908Ssteve# ifdef GEN_TREES_H 31633908Ssteve gen_trees_header(); 31733908Ssteve# endif 31833908Ssteve#endif /* defined(GEN_TREES_H) || !defined(STDC) */ 31917651Speter} 32017651Speter 32117651Speter/* =========================================================================== 32233908Ssteve * Genererate the file trees.h describing the static trees. 32333908Ssteve */ 32433908Ssteve#ifdef GEN_TREES_H 32533908Ssteve# ifndef DEBUG 32633908Ssteve# include <stdio.h> 32733908Ssteve# endif 32833908Ssteve 32933908Ssteve# define SEPARATOR(i, last, width) \ 33033908Ssteve ((i) == (last)? "\n};\n\n" : \ 33133908Ssteve ((i) % (width) == (width)-1 ? ",\n" : ", ")) 33233908Ssteve 33333908Sstevevoid gen_trees_header() 33433908Ssteve{ 33533908Ssteve FILE *header = fopen("trees.h", "w"); 33633908Ssteve int i; 33733908Ssteve 33833908Ssteve Assert (header != NULL, "Can't open trees.h"); 33933908Ssteve fprintf(header, 340131380Stjr "/* header created automatically with -DGEN_TREES_H */\n\n"); 34133908Ssteve 34233908Ssteve fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n"); 34333908Ssteve for (i = 0; i < L_CODES+2; i++) { 344131380Stjr fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code, 345131380Stjr static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5)); 34633908Ssteve } 34733908Ssteve 34833908Ssteve fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n"); 34933908Ssteve for (i = 0; i < D_CODES; i++) { 350131380Stjr fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code, 351131380Stjr static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5)); 35233908Ssteve } 35333908Ssteve 354206924Sdelphij fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n"); 35533908Ssteve for (i = 0; i < DIST_CODE_LEN; i++) { 356131380Stjr fprintf(header, "%2u%s", _dist_code[i], 357131380Stjr SEPARATOR(i, DIST_CODE_LEN-1, 20)); 35833908Ssteve } 35933908Ssteve 360206924Sdelphij fprintf(header, 361206924Sdelphij "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n"); 36233908Ssteve for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) { 363131380Stjr fprintf(header, "%2u%s", _length_code[i], 364131380Stjr SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20)); 36533908Ssteve } 36633908Ssteve 36733908Ssteve fprintf(header, "local const int base_length[LENGTH_CODES] = {\n"); 36833908Ssteve for (i = 0; i < LENGTH_CODES; i++) { 369131380Stjr fprintf(header, "%1u%s", base_length[i], 370131380Stjr SEPARATOR(i, LENGTH_CODES-1, 20)); 37133908Ssteve } 37233908Ssteve 37333908Ssteve fprintf(header, "local const int base_dist[D_CODES] = {\n"); 37433908Ssteve for (i = 0; i < D_CODES; i++) { 375131380Stjr fprintf(header, "%5u%s", base_dist[i], 376131380Stjr SEPARATOR(i, D_CODES-1, 10)); 37733908Ssteve } 37833908Ssteve 37933908Ssteve fclose(header); 38033908Ssteve} 38133908Ssteve#endif /* GEN_TREES_H */ 38233908Ssteve 38333908Ssteve/* =========================================================================== 38417651Speter * Initialize the tree data structures for a new zlib stream. 38517651Speter */ 386206924Sdelphijvoid ZLIB_INTERNAL _tr_init(s) 38717651Speter deflate_state *s; 38817651Speter{ 38917651Speter tr_static_init(); 39017651Speter 39117651Speter s->l_desc.dyn_tree = s->dyn_ltree; 39217651Speter s->l_desc.stat_desc = &static_l_desc; 39317651Speter 39417651Speter s->d_desc.dyn_tree = s->dyn_dtree; 39517651Speter s->d_desc.stat_desc = &static_d_desc; 39617651Speter 39717651Speter s->bl_desc.dyn_tree = s->bl_tree; 39817651Speter s->bl_desc.stat_desc = &static_bl_desc; 39917651Speter 40017651Speter s->bi_buf = 0; 40117651Speter s->bi_valid = 0; 40217651Speter s->last_eob_len = 8; /* enough lookahead for inflate */ 40317651Speter#ifdef DEBUG 40442471Speter s->compressed_len = 0L; 40517651Speter s->bits_sent = 0L; 40617651Speter#endif 40717651Speter 40817651Speter /* Initialize the first block of the first file: */ 40917651Speter init_block(s); 41017651Speter} 41117651Speter 41217651Speter/* =========================================================================== 41317651Speter * Initialize a new block. 41417651Speter */ 41517651Speterlocal void init_block(s) 41617651Speter deflate_state *s; 41717651Speter{ 41817651Speter int n; /* iterates over tree elements */ 41917651Speter 42017651Speter /* Initialize the trees. */ 42117651Speter for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0; 42217651Speter for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0; 42317651Speter for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0; 42417651Speter 42517651Speter s->dyn_ltree[END_BLOCK].Freq = 1; 42617651Speter s->opt_len = s->static_len = 0L; 42717651Speter s->last_lit = s->matches = 0; 42817651Speter} 42917651Speter 43017651Speter#define SMALLEST 1 43117651Speter/* Index within the heap array of least frequent node in the Huffman tree */ 43217651Speter 43317651Speter 43417651Speter/* =========================================================================== 43517651Speter * Remove the smallest element from the heap and recreate the heap with 43617651Speter * one less element. Updates heap and heap_len. 43717651Speter */ 43817651Speter#define pqremove(s, tree, top) \ 43917651Speter{\ 44017651Speter top = s->heap[SMALLEST]; \ 44117651Speter s->heap[SMALLEST] = s->heap[s->heap_len--]; \ 44217651Speter pqdownheap(s, tree, SMALLEST); \ 44317651Speter} 44417651Speter 44517651Speter/* =========================================================================== 44617651Speter * Compares to subtrees, using the tree depth as tie breaker when 44717651Speter * the subtrees have equal frequency. This minimizes the worst case length. 44817651Speter */ 44917651Speter#define smaller(tree, n, m, depth) \ 45017651Speter (tree[n].Freq < tree[m].Freq || \ 45117651Speter (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) 45217651Speter 45317651Speter/* =========================================================================== 45417651Speter * Restore the heap property by moving down the tree starting at node k, 45517651Speter * exchanging a node with the smallest of its two sons if necessary, stopping 45617651Speter * when the heap property is re-established (each father smaller than its 45717651Speter * two sons). 45817651Speter */ 45917651Speterlocal void pqdownheap(s, tree, k) 46017651Speter deflate_state *s; 46117651Speter ct_data *tree; /* the tree to restore */ 46217651Speter int k; /* node to move down */ 46317651Speter{ 46417651Speter int v = s->heap[k]; 46517651Speter int j = k << 1; /* left son of k */ 46617651Speter while (j <= s->heap_len) { 46717651Speter /* Set j to the smallest of the two sons: */ 46817651Speter if (j < s->heap_len && 46917651Speter smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { 47017651Speter j++; 47117651Speter } 47217651Speter /* Exit if v is smaller than both sons */ 47317651Speter if (smaller(tree, v, s->heap[j], s->depth)) break; 47417651Speter 47517651Speter /* Exchange v with the smallest son */ 47617651Speter s->heap[k] = s->heap[j]; k = j; 47717651Speter 47817651Speter /* And continue down the tree, setting j to the left son of k */ 47917651Speter j <<= 1; 48017651Speter } 48117651Speter s->heap[k] = v; 48217651Speter} 48317651Speter 48417651Speter/* =========================================================================== 48517651Speter * Compute the optimal bit lengths for a tree and update the total bit length 48617651Speter * for the current block. 48717651Speter * IN assertion: the fields freq and dad are set, heap[heap_max] and 48817651Speter * above are the tree nodes sorted by increasing frequency. 48917651Speter * OUT assertions: the field len is set to the optimal bit length, the 49017651Speter * array bl_count contains the frequencies for each bit length. 49117651Speter * The length opt_len is updated; static_len is also updated if stree is 49217651Speter * not null. 49317651Speter */ 49417651Speterlocal void gen_bitlen(s, desc) 49517651Speter deflate_state *s; 49617651Speter tree_desc *desc; /* the tree descriptor */ 49717651Speter{ 49833908Ssteve ct_data *tree = desc->dyn_tree; 49933908Ssteve int max_code = desc->max_code; 50033908Ssteve const ct_data *stree = desc->stat_desc->static_tree; 50133908Ssteve const intf *extra = desc->stat_desc->extra_bits; 50233908Ssteve int base = desc->stat_desc->extra_base; 50333908Ssteve int max_length = desc->stat_desc->max_length; 50417651Speter int h; /* heap index */ 50517651Speter int n, m; /* iterate over the tree elements */ 50617651Speter int bits; /* bit length */ 50717651Speter int xbits; /* extra bits */ 50817651Speter ush f; /* frequency */ 50917651Speter int overflow = 0; /* number of elements with bit length too large */ 51017651Speter 51117651Speter for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0; 51217651Speter 51317651Speter /* In a first pass, compute the optimal bit lengths (which may 51417651Speter * overflow in the case of the bit length tree). 51517651Speter */ 51617651Speter tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ 51717651Speter 51817651Speter for (h = s->heap_max+1; h < HEAP_SIZE; h++) { 51917651Speter n = s->heap[h]; 52017651Speter bits = tree[tree[n].Dad].Len + 1; 52117651Speter if (bits > max_length) bits = max_length, overflow++; 52217651Speter tree[n].Len = (ush)bits; 52317651Speter /* We overwrite tree[n].Dad which is no longer needed */ 52417651Speter 52517651Speter if (n > max_code) continue; /* not a leaf node */ 52617651Speter 52717651Speter s->bl_count[bits]++; 52817651Speter xbits = 0; 52917651Speter if (n >= base) xbits = extra[n-base]; 53017651Speter f = tree[n].Freq; 53117651Speter s->opt_len += (ulg)f * (bits + xbits); 53217651Speter if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits); 53317651Speter } 53417651Speter if (overflow == 0) return; 53517651Speter 53617651Speter Trace((stderr,"\nbit length overflow\n")); 53717651Speter /* This happens for example on obj2 and pic of the Calgary corpus */ 53817651Speter 53917651Speter /* Find the first bit length which could increase: */ 54017651Speter do { 54117651Speter bits = max_length-1; 54217651Speter while (s->bl_count[bits] == 0) bits--; 54317651Speter s->bl_count[bits]--; /* move one leaf down the tree */ 54417651Speter s->bl_count[bits+1] += 2; /* move one overflow item as its brother */ 54517651Speter s->bl_count[max_length]--; 54617651Speter /* The brother of the overflow item also moves one step up, 54717651Speter * but this does not affect bl_count[max_length] 54817651Speter */ 54917651Speter overflow -= 2; 55017651Speter } while (overflow > 0); 55117651Speter 55217651Speter /* Now recompute all bit lengths, scanning in increasing frequency. 55317651Speter * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all 55417651Speter * lengths instead of fixing only the wrong ones. This idea is taken 55517651Speter * from 'ar' written by Haruhiko Okumura.) 55617651Speter */ 55717651Speter for (bits = max_length; bits != 0; bits--) { 55817651Speter n = s->bl_count[bits]; 55917651Speter while (n != 0) { 56017651Speter m = s->heap[--h]; 56117651Speter if (m > max_code) continue; 562157046Sdes if ((unsigned) tree[m].Len != (unsigned) bits) { 56317651Speter Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); 56417651Speter s->opt_len += ((long)bits - (long)tree[m].Len) 56517651Speter *(long)tree[m].Freq; 56617651Speter tree[m].Len = (ush)bits; 56717651Speter } 56817651Speter n--; 56917651Speter } 57017651Speter } 57117651Speter} 57217651Speter 57317651Speter/* =========================================================================== 57417651Speter * Generate the codes for a given tree and bit counts (which need not be 57517651Speter * optimal). 57617651Speter * IN assertion: the array bl_count contains the bit length statistics for 57717651Speter * the given tree and the field len is set for all tree elements. 57817651Speter * OUT assertion: the field code is set for all tree elements of non 57917651Speter * zero code length. 58017651Speter */ 58117651Speterlocal void gen_codes (tree, max_code, bl_count) 58217651Speter ct_data *tree; /* the tree to decorate */ 58317651Speter int max_code; /* largest code with non zero frequency */ 58417651Speter ushf *bl_count; /* number of codes at each bit length */ 58517651Speter{ 58617651Speter ush next_code[MAX_BITS+1]; /* next code value for each bit length */ 58717651Speter ush code = 0; /* running code value */ 58817651Speter int bits; /* bit index */ 58917651Speter int n; /* code index */ 59017651Speter 59117651Speter /* The distribution counts are first used to generate the code values 59217651Speter * without bit reversal. 59317651Speter */ 59417651Speter for (bits = 1; bits <= MAX_BITS; bits++) { 59517651Speter next_code[bits] = code = (code + bl_count[bits-1]) << 1; 59617651Speter } 59717651Speter /* Check that the bit counts in bl_count are consistent. The last code 59817651Speter * must be all ones. 59917651Speter */ 60017651Speter Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, 60117651Speter "inconsistent bit counts"); 60217651Speter Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); 60317651Speter 60417651Speter for (n = 0; n <= max_code; n++) { 60517651Speter int len = tree[n].Len; 60617651Speter if (len == 0) continue; 60717651Speter /* Now reverse the bits */ 60817651Speter tree[n].Code = bi_reverse(next_code[len]++, len); 60917651Speter 61017651Speter Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", 61117651Speter n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); 61217651Speter } 61317651Speter} 61417651Speter 61517651Speter/* =========================================================================== 61617651Speter * Construct one Huffman tree and assigns the code bit strings and lengths. 61717651Speter * Update the total bit length for the current block. 61817651Speter * IN assertion: the field freq is set for all tree elements. 61917651Speter * OUT assertions: the fields len and code are set to the optimal bit length 62017651Speter * and corresponding code. The length opt_len is updated; static_len is 62117651Speter * also updated if stree is not null. The field max_code is set. 62217651Speter */ 62317651Speterlocal void build_tree(s, desc) 62417651Speter deflate_state *s; 62517651Speter tree_desc *desc; /* the tree descriptor */ 62617651Speter{ 62733908Ssteve ct_data *tree = desc->dyn_tree; 62833908Ssteve const ct_data *stree = desc->stat_desc->static_tree; 62933908Ssteve int elems = desc->stat_desc->elems; 63017651Speter int n, m; /* iterate over heap elements */ 63117651Speter int max_code = -1; /* largest code with non zero frequency */ 63217651Speter int node; /* new node being created */ 63317651Speter 63417651Speter /* Construct the initial heap, with least frequent element in 63517651Speter * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. 63617651Speter * heap[0] is not used. 63717651Speter */ 63817651Speter s->heap_len = 0, s->heap_max = HEAP_SIZE; 63917651Speter 64017651Speter for (n = 0; n < elems; n++) { 64117651Speter if (tree[n].Freq != 0) { 64217651Speter s->heap[++(s->heap_len)] = max_code = n; 64317651Speter s->depth[n] = 0; 64417651Speter } else { 64517651Speter tree[n].Len = 0; 64617651Speter } 64717651Speter } 64817651Speter 64917651Speter /* The pkzip format requires that at least one distance code exists, 65017651Speter * and that at least one bit should be sent even if there is only one 65117651Speter * possible code. So to avoid special checks later on we force at least 65217651Speter * two codes of non zero frequency. 65317651Speter */ 65417651Speter while (s->heap_len < 2) { 65517651Speter node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0); 65617651Speter tree[node].Freq = 1; 65717651Speter s->depth[node] = 0; 65817651Speter s->opt_len--; if (stree) s->static_len -= stree[node].Len; 65917651Speter /* node is 0 or 1 so it does not have extra bits */ 66017651Speter } 66117651Speter desc->max_code = max_code; 66217651Speter 66317651Speter /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, 66417651Speter * establish sub-heaps of increasing lengths: 66517651Speter */ 66617651Speter for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n); 66717651Speter 66817651Speter /* Construct the Huffman tree by repeatedly combining the least two 66917651Speter * frequent nodes. 67017651Speter */ 67117651Speter node = elems; /* next internal node of the tree */ 67217651Speter do { 67317651Speter pqremove(s, tree, n); /* n = node of least frequency */ 67417651Speter m = s->heap[SMALLEST]; /* m = node of next least frequency */ 67517651Speter 67617651Speter s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */ 67717651Speter s->heap[--(s->heap_max)] = m; 67817651Speter 67917651Speter /* Create a new node father of n and m */ 68017651Speter tree[node].Freq = tree[n].Freq + tree[m].Freq; 681131380Stjr s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ? 682131380Stjr s->depth[n] : s->depth[m]) + 1); 68317651Speter tree[n].Dad = tree[m].Dad = (ush)node; 68417651Speter#ifdef DUMP_BL_TREE 68517651Speter if (tree == s->bl_tree) { 68617651Speter fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", 68717651Speter node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); 68817651Speter } 68917651Speter#endif 69017651Speter /* and insert the new node in the heap */ 69117651Speter s->heap[SMALLEST] = node++; 69217651Speter pqdownheap(s, tree, SMALLEST); 69317651Speter 69417651Speter } while (s->heap_len >= 2); 69517651Speter 69617651Speter s->heap[--(s->heap_max)] = s->heap[SMALLEST]; 69717651Speter 69817651Speter /* At this point, the fields freq and dad are set. We can now 69917651Speter * generate the bit lengths. 70017651Speter */ 70117651Speter gen_bitlen(s, (tree_desc *)desc); 70217651Speter 70317651Speter /* The field len is now set, we can generate the bit codes */ 70417651Speter gen_codes ((ct_data *)tree, max_code, s->bl_count); 70517651Speter} 70617651Speter 70717651Speter/* =========================================================================== 70817651Speter * Scan a literal or distance tree to determine the frequencies of the codes 70917651Speter * in the bit length tree. 71017651Speter */ 71117651Speterlocal void scan_tree (s, tree, max_code) 71217651Speter deflate_state *s; 71317651Speter ct_data *tree; /* the tree to be scanned */ 71417651Speter int max_code; /* and its largest code of non zero frequency */ 71517651Speter{ 71617651Speter int n; /* iterates over all tree elements */ 71717651Speter int prevlen = -1; /* last emitted length */ 71817651Speter int curlen; /* length of current code */ 71917651Speter int nextlen = tree[0].Len; /* length of next code */ 72017651Speter int count = 0; /* repeat count of the current code */ 72117651Speter int max_count = 7; /* max repeat count */ 72217651Speter int min_count = 4; /* min repeat count */ 72317651Speter 72417651Speter if (nextlen == 0) max_count = 138, min_count = 3; 72517651Speter tree[max_code+1].Len = (ush)0xffff; /* guard */ 72617651Speter 72717651Speter for (n = 0; n <= max_code; n++) { 72817651Speter curlen = nextlen; nextlen = tree[n+1].Len; 72917651Speter if (++count < max_count && curlen == nextlen) { 73017651Speter continue; 73117651Speter } else if (count < min_count) { 73217651Speter s->bl_tree[curlen].Freq += count; 73317651Speter } else if (curlen != 0) { 73417651Speter if (curlen != prevlen) s->bl_tree[curlen].Freq++; 73517651Speter s->bl_tree[REP_3_6].Freq++; 73617651Speter } else if (count <= 10) { 73717651Speter s->bl_tree[REPZ_3_10].Freq++; 73817651Speter } else { 73917651Speter s->bl_tree[REPZ_11_138].Freq++; 74017651Speter } 74117651Speter count = 0; prevlen = curlen; 74217651Speter if (nextlen == 0) { 74317651Speter max_count = 138, min_count = 3; 74417651Speter } else if (curlen == nextlen) { 74517651Speter max_count = 6, min_count = 3; 74617651Speter } else { 74717651Speter max_count = 7, min_count = 4; 74817651Speter } 74917651Speter } 75017651Speter} 75117651Speter 75217651Speter/* =========================================================================== 75317651Speter * Send a literal or distance tree in compressed form, using the codes in 75417651Speter * bl_tree. 75517651Speter */ 75617651Speterlocal void send_tree (s, tree, max_code) 75717651Speter deflate_state *s; 75817651Speter ct_data *tree; /* the tree to be scanned */ 75917651Speter int max_code; /* and its largest code of non zero frequency */ 76017651Speter{ 76117651Speter int n; /* iterates over all tree elements */ 76217651Speter int prevlen = -1; /* last emitted length */ 76317651Speter int curlen; /* length of current code */ 76417651Speter int nextlen = tree[0].Len; /* length of next code */ 76517651Speter int count = 0; /* repeat count of the current code */ 76617651Speter int max_count = 7; /* max repeat count */ 76717651Speter int min_count = 4; /* min repeat count */ 76817651Speter 76917651Speter /* tree[max_code+1].Len = -1; */ /* guard already set */ 77017651Speter if (nextlen == 0) max_count = 138, min_count = 3; 77117651Speter 77217651Speter for (n = 0; n <= max_code; n++) { 77317651Speter curlen = nextlen; nextlen = tree[n+1].Len; 77417651Speter if (++count < max_count && curlen == nextlen) { 77517651Speter continue; 77617651Speter } else if (count < min_count) { 77717651Speter do { send_code(s, curlen, s->bl_tree); } while (--count != 0); 77817651Speter 77917651Speter } else if (curlen != 0) { 78017651Speter if (curlen != prevlen) { 78117651Speter send_code(s, curlen, s->bl_tree); count--; 78217651Speter } 78317651Speter Assert(count >= 3 && count <= 6, " 3_6?"); 78417651Speter send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2); 78517651Speter 78617651Speter } else if (count <= 10) { 78717651Speter send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3); 78817651Speter 78917651Speter } else { 79017651Speter send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7); 79117651Speter } 79217651Speter count = 0; prevlen = curlen; 79317651Speter if (nextlen == 0) { 79417651Speter max_count = 138, min_count = 3; 79517651Speter } else if (curlen == nextlen) { 79617651Speter max_count = 6, min_count = 3; 79717651Speter } else { 79817651Speter max_count = 7, min_count = 4; 79917651Speter } 80017651Speter } 80117651Speter} 80217651Speter 80317651Speter/* =========================================================================== 80417651Speter * Construct the Huffman tree for the bit lengths and return the index in 80517651Speter * bl_order of the last bit length code to send. 80617651Speter */ 80717651Speterlocal int build_bl_tree(s) 80817651Speter deflate_state *s; 80917651Speter{ 81017651Speter int max_blindex; /* index of last bit length code of non zero freq */ 81117651Speter 81217651Speter /* Determine the bit length frequencies for literal and distance trees */ 81317651Speter scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code); 81417651Speter scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code); 81517651Speter 81617651Speter /* Build the bit length tree: */ 81717651Speter build_tree(s, (tree_desc *)(&(s->bl_desc))); 81817651Speter /* opt_len now includes the length of the tree representations, except 81917651Speter * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. 82017651Speter */ 82117651Speter 82217651Speter /* Determine the number of bit length codes to send. The pkzip format 82317651Speter * requires that at least 4 bit length codes be sent. (appnote.txt says 82417651Speter * 3 but the actual value used is 4.) 82517651Speter */ 82617651Speter for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { 82717651Speter if (s->bl_tree[bl_order[max_blindex]].Len != 0) break; 82817651Speter } 82917651Speter /* Update opt_len to include the bit length tree and counts */ 83017651Speter s->opt_len += 3*(max_blindex+1) + 5+5+4; 83117651Speter Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", 83217651Speter s->opt_len, s->static_len)); 83317651Speter 83417651Speter return max_blindex; 83517651Speter} 83617651Speter 83717651Speter/* =========================================================================== 83817651Speter * Send the header for a block using dynamic Huffman trees: the counts, the 83917651Speter * lengths of the bit length codes, the literal tree and the distance tree. 84017651Speter * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. 84117651Speter */ 84217651Speterlocal void send_all_trees(s, lcodes, dcodes, blcodes) 84317651Speter deflate_state *s; 84417651Speter int lcodes, dcodes, blcodes; /* number of codes for each tree */ 84517651Speter{ 84617651Speter int rank; /* index in bl_order */ 84717651Speter 84817651Speter Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); 84917651Speter Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, 85017651Speter "too many codes"); 85117651Speter Tracev((stderr, "\nbl counts: ")); 85217651Speter send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */ 85317651Speter send_bits(s, dcodes-1, 5); 85417651Speter send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */ 85517651Speter for (rank = 0; rank < blcodes; rank++) { 85617651Speter Tracev((stderr, "\nbl code %2d ", bl_order[rank])); 85717651Speter send_bits(s, s->bl_tree[bl_order[rank]].Len, 3); 85817651Speter } 85917651Speter Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent)); 86017651Speter 86117651Speter send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */ 86217651Speter Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent)); 86317651Speter 86417651Speter send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */ 86517651Speter Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent)); 86617651Speter} 86717651Speter 86817651Speter/* =========================================================================== 86917651Speter * Send a stored block 87017651Speter */ 871206924Sdelphijvoid ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last) 87217651Speter deflate_state *s; 87317651Speter charf *buf; /* input block */ 87417651Speter ulg stored_len; /* length of input block */ 875205471Sdelphij int last; /* one if this is the last block for a file */ 87617651Speter{ 877205471Sdelphij send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */ 87842471Speter#ifdef DEBUG 87917651Speter s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L; 88017651Speter s->compressed_len += (stored_len + 4) << 3; 88142471Speter#endif 88217651Speter copy_block(s, buf, (unsigned)stored_len, 1); /* with header */ 88317651Speter} 88417651Speter 88517651Speter/* =========================================================================== 88617651Speter * Send one empty static block to give enough lookahead for inflate. 88717651Speter * This takes 10 bits, of which 7 may remain in the bit buffer. 88817651Speter * The current inflate code requires 9 bits of lookahead. If the 88917651Speter * last two codes for the previous block (real code plus EOB) were coded 89017651Speter * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode 89117651Speter * the last real code. In this case we send two empty static blocks instead 89217651Speter * of one. (There are no problems if the previous block is stored or fixed.) 89317651Speter * To simplify the code, we assume the worst case of last real code encoded 89417651Speter * on one bit only. 89517651Speter */ 896206924Sdelphijvoid ZLIB_INTERNAL _tr_align(s) 89717651Speter deflate_state *s; 89817651Speter{ 89917651Speter send_bits(s, STATIC_TREES<<1, 3); 90017651Speter send_code(s, END_BLOCK, static_ltree); 90142471Speter#ifdef DEBUG 90217651Speter s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ 90342471Speter#endif 90417651Speter bi_flush(s); 90517651Speter /* Of the 10 bits for the empty block, we have already sent 90617651Speter * (10 - bi_valid) bits. The lookahead for the last real code (before 90717651Speter * the EOB of the previous block) was thus at least one plus the length 90817651Speter * of the EOB plus what we have just sent of the empty static block. 90917651Speter */ 91017651Speter if (1 + s->last_eob_len + 10 - s->bi_valid < 9) { 91117651Speter send_bits(s, STATIC_TREES<<1, 3); 91217651Speter send_code(s, END_BLOCK, static_ltree); 91342471Speter#ifdef DEBUG 91417651Speter s->compressed_len += 10L; 91542471Speter#endif 91617651Speter bi_flush(s); 91717651Speter } 91817651Speter s->last_eob_len = 7; 91917651Speter} 92017651Speter 92117651Speter/* =========================================================================== 92217651Speter * Determine the best encoding for the current block: dynamic trees, static 92342471Speter * trees or store, and output the encoded block to the zip file. 92417651Speter */ 925206924Sdelphijvoid ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last) 92617651Speter deflate_state *s; 92717651Speter charf *buf; /* input block, or NULL if too old */ 92817651Speter ulg stored_len; /* length of input block */ 929205471Sdelphij int last; /* one if this is the last block for a file */ 93017651Speter{ 93117651Speter ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ 93217651Speter int max_blindex = 0; /* index of last bit length code of non zero freq */ 93317651Speter 93417651Speter /* Build the Huffman trees unless a stored block is forced */ 93517651Speter if (s->level > 0) { 93617651Speter 937157046Sdes /* Check if the file is binary or text */ 938205471Sdelphij if (s->strm->data_type == Z_UNKNOWN) 939205471Sdelphij s->strm->data_type = detect_data_type(s); 94017651Speter 941131380Stjr /* Construct the literal and distance trees */ 942131380Stjr build_tree(s, (tree_desc *)(&(s->l_desc))); 943131380Stjr Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len, 944131380Stjr s->static_len)); 94517651Speter 946131380Stjr build_tree(s, (tree_desc *)(&(s->d_desc))); 947131380Stjr Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len, 948131380Stjr s->static_len)); 949131380Stjr /* At this point, opt_len and static_len are the total bit lengths of 950131380Stjr * the compressed block data, excluding the tree representations. 951131380Stjr */ 95217651Speter 953131380Stjr /* Build the bit length tree for the above two trees, and get the index 954131380Stjr * in bl_order of the last bit length code to send. 955131380Stjr */ 956131380Stjr max_blindex = build_bl_tree(s); 95717651Speter 958131380Stjr /* Determine the best encoding. Compute the block lengths in bytes. */ 959131380Stjr opt_lenb = (s->opt_len+3+7)>>3; 960131380Stjr static_lenb = (s->static_len+3+7)>>3; 96117651Speter 962131380Stjr Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ", 963131380Stjr opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, 964131380Stjr s->last_lit)); 96517651Speter 966131380Stjr if (static_lenb <= opt_lenb) opt_lenb = static_lenb; 96717651Speter 96817651Speter } else { 96917651Speter Assert(buf != (char*)0, "lost buf"); 970131380Stjr opt_lenb = static_lenb = stored_len + 5; /* force a stored block */ 97117651Speter } 97217651Speter 97317651Speter#ifdef FORCE_STORED 97417651Speter if (buf != (char*)0) { /* force stored block */ 97517651Speter#else 97617651Speter if (stored_len+4 <= opt_lenb && buf != (char*)0) { 97717651Speter /* 4: two words for the lengths */ 97817651Speter#endif 97917651Speter /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. 98017651Speter * Otherwise we can't have processed more than WSIZE input bytes since 98117651Speter * the last block flush, because compression would have been 98217651Speter * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to 98317651Speter * transform a block into a stored block. 98417651Speter */ 985205471Sdelphij _tr_stored_block(s, buf, stored_len, last); 98617651Speter 98717651Speter#ifdef FORCE_STATIC 98817651Speter } else if (static_lenb >= 0) { /* force static trees */ 98917651Speter#else 990157046Sdes } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) { 99117651Speter#endif 992205471Sdelphij send_bits(s, (STATIC_TREES<<1)+last, 3); 99317651Speter compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree); 99442471Speter#ifdef DEBUG 99517651Speter s->compressed_len += 3 + s->static_len; 99642471Speter#endif 99717651Speter } else { 998205471Sdelphij send_bits(s, (DYN_TREES<<1)+last, 3); 99917651Speter send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1, 100017651Speter max_blindex+1); 100117651Speter compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree); 100242471Speter#ifdef DEBUG 100317651Speter s->compressed_len += 3 + s->opt_len; 100442471Speter#endif 100517651Speter } 100617651Speter Assert (s->compressed_len == s->bits_sent, "bad compressed size"); 100742471Speter /* The above check is made mod 2^32, for files larger than 512 MB 100842471Speter * and uLong implemented on 32 bits. 100942471Speter */ 101017651Speter init_block(s); 101117651Speter 1012205471Sdelphij if (last) { 101317651Speter bi_windup(s); 101442471Speter#ifdef DEBUG 101517651Speter s->compressed_len += 7; /* align on byte boundary */ 101642471Speter#endif 101717651Speter } 101817651Speter Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3, 1019205471Sdelphij s->compressed_len-7*last)); 102017651Speter} 102117651Speter 102217651Speter/* =========================================================================== 102317651Speter * Save the match info and tally the frequency counts. Return true if 102417651Speter * the current block must be flushed. 102517651Speter */ 1026206924Sdelphijint ZLIB_INTERNAL _tr_tally (s, dist, lc) 102717651Speter deflate_state *s; 102817651Speter unsigned dist; /* distance of matched string */ 102917651Speter unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ 103017651Speter{ 103117651Speter s->d_buf[s->last_lit] = (ush)dist; 103217651Speter s->l_buf[s->last_lit++] = (uch)lc; 103317651Speter if (dist == 0) { 103417651Speter /* lc is the unmatched char */ 103517651Speter s->dyn_ltree[lc].Freq++; 103617651Speter } else { 103717651Speter s->matches++; 103817651Speter /* Here, lc is the match length - MIN_MATCH */ 103917651Speter dist--; /* dist = match distance - 1 */ 104017651Speter Assert((ush)dist < (ush)MAX_DIST(s) && 104117651Speter (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && 104217651Speter (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match"); 104317651Speter 104433908Ssteve s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++; 104517651Speter s->dyn_dtree[d_code(dist)].Freq++; 104617651Speter } 104717651Speter 104833908Ssteve#ifdef TRUNCATE_BLOCK 104917651Speter /* Try to guess if it is profitable to stop the current block here */ 105033908Ssteve if ((s->last_lit & 0x1fff) == 0 && s->level > 2) { 105117651Speter /* Compute an upper bound for the compressed length */ 105217651Speter ulg out_length = (ulg)s->last_lit*8L; 105317651Speter ulg in_length = (ulg)((long)s->strstart - s->block_start); 105417651Speter int dcode; 105517651Speter for (dcode = 0; dcode < D_CODES; dcode++) { 105617651Speter out_length += (ulg)s->dyn_dtree[dcode].Freq * 105717651Speter (5L+extra_dbits[dcode]); 105817651Speter } 105917651Speter out_length >>= 3; 106017651Speter Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ", 106117651Speter s->last_lit, in_length, out_length, 106217651Speter 100L - out_length*100L/in_length)); 106317651Speter if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1; 106417651Speter } 106533908Ssteve#endif 106617651Speter return (s->last_lit == s->lit_bufsize-1); 106717651Speter /* We avoid equality with lit_bufsize because of wraparound at 64K 106817651Speter * on 16 bit machines and because stored blocks are restricted to 106917651Speter * 64K-1 bytes. 107017651Speter */ 107117651Speter} 107217651Speter 107317651Speter/* =========================================================================== 107417651Speter * Send the block data compressed using the given Huffman trees 107517651Speter */ 107617651Speterlocal void compress_block(s, ltree, dtree) 107717651Speter deflate_state *s; 107817651Speter ct_data *ltree; /* literal tree */ 107917651Speter ct_data *dtree; /* distance tree */ 108017651Speter{ 108117651Speter unsigned dist; /* distance of matched string */ 108217651Speter int lc; /* match length or unmatched char (if dist == 0) */ 108317651Speter unsigned lx = 0; /* running index in l_buf */ 108417651Speter unsigned code; /* the code to send */ 108517651Speter int extra; /* number of extra bits to send */ 108617651Speter 108717651Speter if (s->last_lit != 0) do { 108817651Speter dist = s->d_buf[lx]; 108917651Speter lc = s->l_buf[lx++]; 109017651Speter if (dist == 0) { 109117651Speter send_code(s, lc, ltree); /* send a literal byte */ 109217651Speter Tracecv(isgraph(lc), (stderr," '%c' ", lc)); 109317651Speter } else { 109417651Speter /* Here, lc is the match length - MIN_MATCH */ 109533908Ssteve code = _length_code[lc]; 109617651Speter send_code(s, code+LITERALS+1, ltree); /* send the length code */ 109717651Speter extra = extra_lbits[code]; 109817651Speter if (extra != 0) { 109917651Speter lc -= base_length[code]; 110017651Speter send_bits(s, lc, extra); /* send the extra length bits */ 110117651Speter } 110217651Speter dist--; /* dist is now the match distance - 1 */ 110317651Speter code = d_code(dist); 110417651Speter Assert (code < D_CODES, "bad d_code"); 110517651Speter 110617651Speter send_code(s, code, dtree); /* send the distance code */ 110717651Speter extra = extra_dbits[code]; 110817651Speter if (extra != 0) { 110917651Speter dist -= base_dist[code]; 111017651Speter send_bits(s, dist, extra); /* send the extra distance bits */ 111117651Speter } 111217651Speter } /* literal or match pair ? */ 111317651Speter 111417651Speter /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */ 1115131380Stjr Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx, 1116131380Stjr "pendingBuf overflow"); 111717651Speter 111817651Speter } while (lx < s->last_lit); 111917651Speter 112017651Speter send_code(s, END_BLOCK, ltree); 112117651Speter s->last_eob_len = ltree[END_BLOCK].Len; 112217651Speter} 112317651Speter 112417651Speter/* =========================================================================== 1125205471Sdelphij * Check if the data type is TEXT or BINARY, using the following algorithm: 1126205471Sdelphij * - TEXT if the two conditions below are satisfied: 1127205471Sdelphij * a) There are no non-portable control characters belonging to the 1128205471Sdelphij * "black list" (0..6, 14..25, 28..31). 1129205471Sdelphij * b) There is at least one printable character belonging to the 1130205471Sdelphij * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255). 1131205471Sdelphij * - BINARY otherwise. 1132205471Sdelphij * - The following partially-portable control characters form a 1133205471Sdelphij * "gray list" that is ignored in this detection algorithm: 1134205471Sdelphij * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}). 1135157046Sdes * IN assertion: the fields Freq of dyn_ltree are set. 113617651Speter */ 1137205471Sdelphijlocal int detect_data_type(s) 113817651Speter deflate_state *s; 113917651Speter{ 1140205471Sdelphij /* black_mask is the bit mask of black-listed bytes 1141205471Sdelphij * set bits 0..6, 14..25, and 28..31 1142205471Sdelphij * 0xf3ffc07f = binary 11110011111111111100000001111111 1143205471Sdelphij */ 1144205471Sdelphij unsigned long black_mask = 0xf3ffc07fUL; 1145157046Sdes int n; 1146157046Sdes 1147205471Sdelphij /* Check for non-textual ("black-listed") bytes. */ 1148205471Sdelphij for (n = 0; n <= 31; n++, black_mask >>= 1) 1149205471Sdelphij if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0)) 1150205471Sdelphij return Z_BINARY; 1151205471Sdelphij 1152205471Sdelphij /* Check for textual ("white-listed") bytes. */ 1153205471Sdelphij if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0 1154205471Sdelphij || s->dyn_ltree[13].Freq != 0) 1155205471Sdelphij return Z_TEXT; 1156205471Sdelphij for (n = 32; n < LITERALS; n++) 1157157046Sdes if (s->dyn_ltree[n].Freq != 0) 1158205471Sdelphij return Z_TEXT; 1159205471Sdelphij 1160205471Sdelphij /* There are no "black-listed" or "white-listed" bytes: 1161205471Sdelphij * this stream either is empty or has tolerated ("gray-listed") bytes only. 1162205471Sdelphij */ 1163205471Sdelphij return Z_BINARY; 116417651Speter} 116517651Speter 116617651Speter/* =========================================================================== 116717651Speter * Reverse the first len bits of a code, using straightforward code (a faster 116817651Speter * method would use a table) 116917651Speter * IN assertion: 1 <= len <= 15 117017651Speter */ 117117651Speterlocal unsigned bi_reverse(code, len) 117217651Speter unsigned code; /* the value to invert */ 117317651Speter int len; /* its bit length */ 117417651Speter{ 117517651Speter register unsigned res = 0; 117617651Speter do { 117717651Speter res |= code & 1; 117817651Speter code >>= 1, res <<= 1; 117917651Speter } while (--len > 0); 118017651Speter return res >> 1; 118117651Speter} 118217651Speter 118317651Speter/* =========================================================================== 118417651Speter * Flush the bit buffer, keeping at most 7 bits in it. 118517651Speter */ 118617651Speterlocal void bi_flush(s) 118717651Speter deflate_state *s; 118817651Speter{ 118917651Speter if (s->bi_valid == 16) { 119017651Speter put_short(s, s->bi_buf); 119117651Speter s->bi_buf = 0; 119217651Speter s->bi_valid = 0; 119317651Speter } else if (s->bi_valid >= 8) { 119417651Speter put_byte(s, (Byte)s->bi_buf); 119517651Speter s->bi_buf >>= 8; 119617651Speter s->bi_valid -= 8; 119717651Speter } 119817651Speter} 119917651Speter 120017651Speter/* =========================================================================== 120117651Speter * Flush the bit buffer and align the output on a byte boundary 120217651Speter */ 120317651Speterlocal void bi_windup(s) 120417651Speter deflate_state *s; 120517651Speter{ 120617651Speter if (s->bi_valid > 8) { 120717651Speter put_short(s, s->bi_buf); 120817651Speter } else if (s->bi_valid > 0) { 120917651Speter put_byte(s, (Byte)s->bi_buf); 121017651Speter } 121117651Speter s->bi_buf = 0; 121217651Speter s->bi_valid = 0; 121317651Speter#ifdef DEBUG 121417651Speter s->bits_sent = (s->bits_sent+7) & ~7; 121517651Speter#endif 121617651Speter} 121717651Speter 121817651Speter/* =========================================================================== 121917651Speter * Copy a stored block, storing first the length and its 122017651Speter * one's complement if requested. 122117651Speter */ 122217651Speterlocal void copy_block(s, buf, len, header) 122317651Speter deflate_state *s; 122417651Speter charf *buf; /* the input data */ 122517651Speter unsigned len; /* its length */ 122617651Speter int header; /* true if block header must be written */ 122717651Speter{ 122817651Speter bi_windup(s); /* align on byte boundary */ 122917651Speter s->last_eob_len = 8; /* enough lookahead for inflate */ 123017651Speter 123117651Speter if (header) { 1232131380Stjr put_short(s, (ush)len); 123317651Speter put_short(s, (ush)~len); 123417651Speter#ifdef DEBUG 123517651Speter s->bits_sent += 2*16; 123617651Speter#endif 123717651Speter } 123817651Speter#ifdef DEBUG 123917651Speter s->bits_sent += (ulg)len<<3; 124017651Speter#endif 124117651Speter while (len--) { 124217651Speter put_byte(s, *buf++); 124317651Speter } 124417651Speter} 1245