trees.c revision 17651
117651Speter/* trees.c -- output deflated data using Huffman coding 217651Speter * Copyright (C) 1995-1996 Jean-loup Gailly 317651Speter * For conditions of distribution and use, see copyright notice in zlib.h 417651Speter */ 517651Speter 617651Speter/* 717651Speter * ALGORITHM 817651Speter * 917651Speter * The "deflation" process uses several Huffman trees. The more 1017651Speter * common source values are represented by shorter bit sequences. 1117651Speter * 1217651Speter * Each code tree is stored in a compressed form which is itself 1317651Speter * a Huffman encoding of the lengths of all the code strings (in 1417651Speter * ascending order by source values). The actual code strings are 1517651Speter * reconstructed from the lengths in the inflate process, as described 1617651Speter * in the deflate specification. 1717651Speter * 1817651Speter * REFERENCES 1917651Speter * 2017651Speter * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification". 2117651Speter * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc 2217651Speter * 2317651Speter * Storer, James A. 2417651Speter * Data Compression: Methods and Theory, pp. 49-50. 2517651Speter * Computer Science Press, 1988. ISBN 0-7167-8156-5. 2617651Speter * 2717651Speter * Sedgewick, R. 2817651Speter * Algorithms, p290. 2917651Speter * Addison-Wesley, 1983. ISBN 0-201-06672-6. 3017651Speter */ 3117651Speter 3217651Speter/* $Id: trees.c,v 1.11 1996/07/24 13:41:06 me Exp $ */ 3317651Speter 3417651Speter#include "deflate.h" 3517651Speter 3617651Speter#ifdef DEBUG 3717651Speter# include <ctype.h> 3817651Speter#endif 3917651Speter 4017651Speter/* =========================================================================== 4117651Speter * Constants 4217651Speter */ 4317651Speter 4417651Speter#define MAX_BL_BITS 7 4517651Speter/* Bit length codes must not exceed MAX_BL_BITS bits */ 4617651Speter 4717651Speter#define END_BLOCK 256 4817651Speter/* end of block literal code */ 4917651Speter 5017651Speter#define REP_3_6 16 5117651Speter/* repeat previous bit length 3-6 times (2 bits of repeat count) */ 5217651Speter 5317651Speter#define REPZ_3_10 17 5417651Speter/* repeat a zero length 3-10 times (3 bits of repeat count) */ 5517651Speter 5617651Speter#define REPZ_11_138 18 5717651Speter/* repeat a zero length 11-138 times (7 bits of repeat count) */ 5817651Speter 5917651Speterlocal int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ 6017651Speter = {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}; 6117651Speter 6217651Speterlocal int extra_dbits[D_CODES] /* extra bits for each distance code */ 6317651Speter = {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}; 6417651Speter 6517651Speterlocal int extra_blbits[BL_CODES]/* extra bits for each bit length code */ 6617651Speter = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; 6717651Speter 6817651Speterlocal uch bl_order[BL_CODES] 6917651Speter = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; 7017651Speter/* The lengths of the bit length codes are sent in order of decreasing 7117651Speter * probability, to avoid transmitting the lengths for unused bit length codes. 7217651Speter */ 7317651Speter 7417651Speter#define Buf_size (8 * 2*sizeof(char)) 7517651Speter/* Number of bits used within bi_buf. (bi_buf might be implemented on 7617651Speter * more than 16 bits on some systems.) 7717651Speter */ 7817651Speter 7917651Speter/* =========================================================================== 8017651Speter * Local data. These are initialized only once. 8117651Speter */ 8217651Speter 8317651Speterlocal ct_data static_ltree[L_CODES+2]; 8417651Speter/* The static literal tree. Since the bit lengths are imposed, there is no 8517651Speter * need for the L_CODES extra codes used during heap construction. However 8617651Speter * The codes 286 and 287 are needed to build a canonical tree (see _tr_init 8717651Speter * below). 8817651Speter */ 8917651Speter 9017651Speterlocal ct_data static_dtree[D_CODES]; 9117651Speter/* The static distance tree. (Actually a trivial tree since all codes use 9217651Speter * 5 bits.) 9317651Speter */ 9417651Speter 9517651Speterlocal uch dist_code[512]; 9617651Speter/* distance codes. The first 256 values correspond to the distances 9717651Speter * 3 .. 258, the last 256 values correspond to the top 8 bits of 9817651Speter * the 15 bit distances. 9917651Speter */ 10017651Speter 10117651Speterlocal uch length_code[MAX_MATCH-MIN_MATCH+1]; 10217651Speter/* length code for each normalized match length (0 == MIN_MATCH) */ 10317651Speter 10417651Speterlocal int base_length[LENGTH_CODES]; 10517651Speter/* First normalized length for each code (0 = MIN_MATCH) */ 10617651Speter 10717651Speterlocal int base_dist[D_CODES]; 10817651Speter/* First normalized distance for each code (0 = distance of 1) */ 10917651Speter 11017651Speterstruct static_tree_desc_s { 11117651Speter ct_data *static_tree; /* static tree or NULL */ 11217651Speter intf *extra_bits; /* extra bits for each code or NULL */ 11317651Speter int extra_base; /* base index for extra_bits */ 11417651Speter int elems; /* max number of elements in the tree */ 11517651Speter int max_length; /* max bit length for the codes */ 11617651Speter}; 11717651Speter 11817651Speterlocal static_tree_desc static_l_desc = 11917651Speter{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS}; 12017651Speter 12117651Speterlocal static_tree_desc static_d_desc = 12217651Speter{static_dtree, extra_dbits, 0, D_CODES, MAX_BITS}; 12317651Speter 12417651Speterlocal static_tree_desc static_bl_desc = 12517651Speter{(ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS}; 12617651Speter 12717651Speter/* =========================================================================== 12817651Speter * Local (static) routines in this file. 12917651Speter */ 13017651Speter 13117651Speterlocal void tr_static_init OF((void)); 13217651Speterlocal void init_block OF((deflate_state *s)); 13317651Speterlocal void pqdownheap OF((deflate_state *s, ct_data *tree, int k)); 13417651Speterlocal void gen_bitlen OF((deflate_state *s, tree_desc *desc)); 13517651Speterlocal void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count)); 13617651Speterlocal void build_tree OF((deflate_state *s, tree_desc *desc)); 13717651Speterlocal void scan_tree OF((deflate_state *s, ct_data *tree, int max_code)); 13817651Speterlocal void send_tree OF((deflate_state *s, ct_data *tree, int max_code)); 13917651Speterlocal int build_bl_tree OF((deflate_state *s)); 14017651Speterlocal void send_all_trees OF((deflate_state *s, int lcodes, int dcodes, 14117651Speter int blcodes)); 14217651Speterlocal void compress_block OF((deflate_state *s, ct_data *ltree, 14317651Speter ct_data *dtree)); 14417651Speterlocal void set_data_type OF((deflate_state *s)); 14517651Speterlocal unsigned bi_reverse OF((unsigned value, int length)); 14617651Speterlocal void bi_windup OF((deflate_state *s)); 14717651Speterlocal void bi_flush OF((deflate_state *s)); 14817651Speterlocal void copy_block OF((deflate_state *s, charf *buf, unsigned len, 14917651Speter int header)); 15017651Speter 15117651Speter#ifndef DEBUG 15217651Speter# define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len) 15317651Speter /* Send a code of the given tree. c and tree must not have side effects */ 15417651Speter 15517651Speter#else /* DEBUG */ 15617651Speter# define send_code(s, c, tree) \ 15717651Speter { if (verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \ 15817651Speter send_bits(s, tree[c].Code, tree[c].Len); } 15917651Speter#endif 16017651Speter 16117651Speter#define d_code(dist) \ 16217651Speter ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)]) 16317651Speter/* Mapping from a distance to a distance code. dist is the distance - 1 and 16417651Speter * must not have side effects. dist_code[256] and dist_code[257] are never 16517651Speter * used. 16617651Speter */ 16717651Speter 16817651Speter/* =========================================================================== 16917651Speter * Output a short LSB first on the stream. 17017651Speter * IN assertion: there is enough room in pendingBuf. 17117651Speter */ 17217651Speter#define put_short(s, w) { \ 17317651Speter put_byte(s, (uch)((w) & 0xff)); \ 17417651Speter put_byte(s, (uch)((ush)(w) >> 8)); \ 17517651Speter} 17617651Speter 17717651Speter/* =========================================================================== 17817651Speter * Send a value on a given number of bits. 17917651Speter * IN assertion: length <= 16 and value fits in length bits. 18017651Speter */ 18117651Speter#ifdef DEBUG 18217651Speterlocal void send_bits OF((deflate_state *s, int value, int length)); 18317651Speter 18417651Speterlocal void send_bits(s, value, length) 18517651Speter deflate_state *s; 18617651Speter int value; /* value to send */ 18717651Speter int length; /* number of bits */ 18817651Speter{ 18917651Speter Tracevv((stderr," l %2d v %4x ", length, value)); 19017651Speter Assert(length > 0 && length <= 15, "invalid length"); 19117651Speter s->bits_sent += (ulg)length; 19217651Speter 19317651Speter /* If not enough room in bi_buf, use (valid) bits from bi_buf and 19417651Speter * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid)) 19517651Speter * unused bits in value. 19617651Speter */ 19717651Speter if (s->bi_valid > (int)Buf_size - length) { 19817651Speter s->bi_buf |= (value << s->bi_valid); 19917651Speter put_short(s, s->bi_buf); 20017651Speter s->bi_buf = (ush)value >> (Buf_size - s->bi_valid); 20117651Speter s->bi_valid += length - Buf_size; 20217651Speter } else { 20317651Speter s->bi_buf |= value << s->bi_valid; 20417651Speter s->bi_valid += length; 20517651Speter } 20617651Speter} 20717651Speter#else /* !DEBUG */ 20817651Speter 20917651Speter#define send_bits(s, value, length) \ 21017651Speter{ int len = length;\ 21117651Speter if (s->bi_valid > (int)Buf_size - len) {\ 21217651Speter int val = value;\ 21317651Speter s->bi_buf |= (val << s->bi_valid);\ 21417651Speter put_short(s, s->bi_buf);\ 21517651Speter s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\ 21617651Speter s->bi_valid += len - Buf_size;\ 21717651Speter } else {\ 21817651Speter s->bi_buf |= (value) << s->bi_valid;\ 21917651Speter s->bi_valid += len;\ 22017651Speter }\ 22117651Speter} 22217651Speter#endif /* DEBUG */ 22317651Speter 22417651Speter 22517651Speter#define MAX(a,b) (a >= b ? a : b) 22617651Speter/* the arguments must not have side effects */ 22717651Speter 22817651Speter/* =========================================================================== 22917651Speter * Initialize the various 'constant' tables. In a multi-threaded environment, 23017651Speter * this function may be called by two threads concurrently, but this is 23117651Speter * harmless since both invocations do exactly the same thing. 23217651Speter */ 23317651Speterlocal void tr_static_init() 23417651Speter{ 23517651Speter static int static_init_done = 0; 23617651Speter int n; /* iterates over tree elements */ 23717651Speter int bits; /* bit counter */ 23817651Speter int length; /* length value */ 23917651Speter int code; /* code value */ 24017651Speter int dist; /* distance index */ 24117651Speter ush bl_count[MAX_BITS+1]; 24217651Speter /* number of codes at each bit length for an optimal tree */ 24317651Speter 24417651Speter if (static_init_done) return; 24517651Speter 24617651Speter /* Initialize the mapping length (0..255) -> length code (0..28) */ 24717651Speter length = 0; 24817651Speter for (code = 0; code < LENGTH_CODES-1; code++) { 24917651Speter base_length[code] = length; 25017651Speter for (n = 0; n < (1<<extra_lbits[code]); n++) { 25117651Speter length_code[length++] = (uch)code; 25217651Speter } 25317651Speter } 25417651Speter Assert (length == 256, "tr_static_init: length != 256"); 25517651Speter /* Note that the length 255 (match length 258) can be represented 25617651Speter * in two different ways: code 284 + 5 bits or code 285, so we 25717651Speter * overwrite length_code[255] to use the best encoding: 25817651Speter */ 25917651Speter length_code[length-1] = (uch)code; 26017651Speter 26117651Speter /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ 26217651Speter dist = 0; 26317651Speter for (code = 0 ; code < 16; code++) { 26417651Speter base_dist[code] = dist; 26517651Speter for (n = 0; n < (1<<extra_dbits[code]); n++) { 26617651Speter dist_code[dist++] = (uch)code; 26717651Speter } 26817651Speter } 26917651Speter Assert (dist == 256, "tr_static_init: dist != 256"); 27017651Speter dist >>= 7; /* from now on, all distances are divided by 128 */ 27117651Speter for ( ; code < D_CODES; code++) { 27217651Speter base_dist[code] = dist << 7; 27317651Speter for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { 27417651Speter dist_code[256 + dist++] = (uch)code; 27517651Speter } 27617651Speter } 27717651Speter Assert (dist == 256, "tr_static_init: 256+dist != 512"); 27817651Speter 27917651Speter /* Construct the codes of the static literal tree */ 28017651Speter for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; 28117651Speter n = 0; 28217651Speter while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; 28317651Speter while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; 28417651Speter while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; 28517651Speter while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; 28617651Speter /* Codes 286 and 287 do not exist, but we must include them in the 28717651Speter * tree construction to get a canonical Huffman tree (longest code 28817651Speter * all ones) 28917651Speter */ 29017651Speter gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count); 29117651Speter 29217651Speter /* The static distance tree is trivial: */ 29317651Speter for (n = 0; n < D_CODES; n++) { 29417651Speter static_dtree[n].Len = 5; 29517651Speter static_dtree[n].Code = bi_reverse((unsigned)n, 5); 29617651Speter } 29717651Speter static_init_done = 1; 29817651Speter} 29917651Speter 30017651Speter/* =========================================================================== 30117651Speter * Initialize the tree data structures for a new zlib stream. 30217651Speter */ 30317651Spetervoid _tr_init(s) 30417651Speter deflate_state *s; 30517651Speter{ 30617651Speter tr_static_init(); 30717651Speter 30817651Speter s->compressed_len = 0L; 30917651Speter 31017651Speter s->l_desc.dyn_tree = s->dyn_ltree; 31117651Speter s->l_desc.stat_desc = &static_l_desc; 31217651Speter 31317651Speter s->d_desc.dyn_tree = s->dyn_dtree; 31417651Speter s->d_desc.stat_desc = &static_d_desc; 31517651Speter 31617651Speter s->bl_desc.dyn_tree = s->bl_tree; 31717651Speter s->bl_desc.stat_desc = &static_bl_desc; 31817651Speter 31917651Speter s->bi_buf = 0; 32017651Speter s->bi_valid = 0; 32117651Speter s->last_eob_len = 8; /* enough lookahead for inflate */ 32217651Speter#ifdef DEBUG 32317651Speter s->bits_sent = 0L; 32417651Speter#endif 32517651Speter 32617651Speter /* Initialize the first block of the first file: */ 32717651Speter init_block(s); 32817651Speter} 32917651Speter 33017651Speter/* =========================================================================== 33117651Speter * Initialize a new block. 33217651Speter */ 33317651Speterlocal void init_block(s) 33417651Speter deflate_state *s; 33517651Speter{ 33617651Speter int n; /* iterates over tree elements */ 33717651Speter 33817651Speter /* Initialize the trees. */ 33917651Speter for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0; 34017651Speter for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0; 34117651Speter for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0; 34217651Speter 34317651Speter s->dyn_ltree[END_BLOCK].Freq = 1; 34417651Speter s->opt_len = s->static_len = 0L; 34517651Speter s->last_lit = s->matches = 0; 34617651Speter} 34717651Speter 34817651Speter#define SMALLEST 1 34917651Speter/* Index within the heap array of least frequent node in the Huffman tree */ 35017651Speter 35117651Speter 35217651Speter/* =========================================================================== 35317651Speter * Remove the smallest element from the heap and recreate the heap with 35417651Speter * one less element. Updates heap and heap_len. 35517651Speter */ 35617651Speter#define pqremove(s, tree, top) \ 35717651Speter{\ 35817651Speter top = s->heap[SMALLEST]; \ 35917651Speter s->heap[SMALLEST] = s->heap[s->heap_len--]; \ 36017651Speter pqdownheap(s, tree, SMALLEST); \ 36117651Speter} 36217651Speter 36317651Speter/* =========================================================================== 36417651Speter * Compares to subtrees, using the tree depth as tie breaker when 36517651Speter * the subtrees have equal frequency. This minimizes the worst case length. 36617651Speter */ 36717651Speter#define smaller(tree, n, m, depth) \ 36817651Speter (tree[n].Freq < tree[m].Freq || \ 36917651Speter (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) 37017651Speter 37117651Speter/* =========================================================================== 37217651Speter * Restore the heap property by moving down the tree starting at node k, 37317651Speter * exchanging a node with the smallest of its two sons if necessary, stopping 37417651Speter * when the heap property is re-established (each father smaller than its 37517651Speter * two sons). 37617651Speter */ 37717651Speterlocal void pqdownheap(s, tree, k) 37817651Speter deflate_state *s; 37917651Speter ct_data *tree; /* the tree to restore */ 38017651Speter int k; /* node to move down */ 38117651Speter{ 38217651Speter int v = s->heap[k]; 38317651Speter int j = k << 1; /* left son of k */ 38417651Speter while (j <= s->heap_len) { 38517651Speter /* Set j to the smallest of the two sons: */ 38617651Speter if (j < s->heap_len && 38717651Speter smaller(tree, s->heap[j+1], s->heap[j], s->depth)) { 38817651Speter j++; 38917651Speter } 39017651Speter /* Exit if v is smaller than both sons */ 39117651Speter if (smaller(tree, v, s->heap[j], s->depth)) break; 39217651Speter 39317651Speter /* Exchange v with the smallest son */ 39417651Speter s->heap[k] = s->heap[j]; k = j; 39517651Speter 39617651Speter /* And continue down the tree, setting j to the left son of k */ 39717651Speter j <<= 1; 39817651Speter } 39917651Speter s->heap[k] = v; 40017651Speter} 40117651Speter 40217651Speter/* =========================================================================== 40317651Speter * Compute the optimal bit lengths for a tree and update the total bit length 40417651Speter * for the current block. 40517651Speter * IN assertion: the fields freq and dad are set, heap[heap_max] and 40617651Speter * above are the tree nodes sorted by increasing frequency. 40717651Speter * OUT assertions: the field len is set to the optimal bit length, the 40817651Speter * array bl_count contains the frequencies for each bit length. 40917651Speter * The length opt_len is updated; static_len is also updated if stree is 41017651Speter * not null. 41117651Speter */ 41217651Speterlocal void gen_bitlen(s, desc) 41317651Speter deflate_state *s; 41417651Speter tree_desc *desc; /* the tree descriptor */ 41517651Speter{ 41617651Speter ct_data *tree = desc->dyn_tree; 41717651Speter int max_code = desc->max_code; 41817651Speter ct_data *stree = desc->stat_desc->static_tree; 41917651Speter intf *extra = desc->stat_desc->extra_bits; 42017651Speter int base = desc->stat_desc->extra_base; 42117651Speter int max_length = desc->stat_desc->max_length; 42217651Speter int h; /* heap index */ 42317651Speter int n, m; /* iterate over the tree elements */ 42417651Speter int bits; /* bit length */ 42517651Speter int xbits; /* extra bits */ 42617651Speter ush f; /* frequency */ 42717651Speter int overflow = 0; /* number of elements with bit length too large */ 42817651Speter 42917651Speter for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0; 43017651Speter 43117651Speter /* In a first pass, compute the optimal bit lengths (which may 43217651Speter * overflow in the case of the bit length tree). 43317651Speter */ 43417651Speter tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */ 43517651Speter 43617651Speter for (h = s->heap_max+1; h < HEAP_SIZE; h++) { 43717651Speter n = s->heap[h]; 43817651Speter bits = tree[tree[n].Dad].Len + 1; 43917651Speter if (bits > max_length) bits = max_length, overflow++; 44017651Speter tree[n].Len = (ush)bits; 44117651Speter /* We overwrite tree[n].Dad which is no longer needed */ 44217651Speter 44317651Speter if (n > max_code) continue; /* not a leaf node */ 44417651Speter 44517651Speter s->bl_count[bits]++; 44617651Speter xbits = 0; 44717651Speter if (n >= base) xbits = extra[n-base]; 44817651Speter f = tree[n].Freq; 44917651Speter s->opt_len += (ulg)f * (bits + xbits); 45017651Speter if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits); 45117651Speter } 45217651Speter if (overflow == 0) return; 45317651Speter 45417651Speter Trace((stderr,"\nbit length overflow\n")); 45517651Speter /* This happens for example on obj2 and pic of the Calgary corpus */ 45617651Speter 45717651Speter /* Find the first bit length which could increase: */ 45817651Speter do { 45917651Speter bits = max_length-1; 46017651Speter while (s->bl_count[bits] == 0) bits--; 46117651Speter s->bl_count[bits]--; /* move one leaf down the tree */ 46217651Speter s->bl_count[bits+1] += 2; /* move one overflow item as its brother */ 46317651Speter s->bl_count[max_length]--; 46417651Speter /* The brother of the overflow item also moves one step up, 46517651Speter * but this does not affect bl_count[max_length] 46617651Speter */ 46717651Speter overflow -= 2; 46817651Speter } while (overflow > 0); 46917651Speter 47017651Speter /* Now recompute all bit lengths, scanning in increasing frequency. 47117651Speter * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all 47217651Speter * lengths instead of fixing only the wrong ones. This idea is taken 47317651Speter * from 'ar' written by Haruhiko Okumura.) 47417651Speter */ 47517651Speter for (bits = max_length; bits != 0; bits--) { 47617651Speter n = s->bl_count[bits]; 47717651Speter while (n != 0) { 47817651Speter m = s->heap[--h]; 47917651Speter if (m > max_code) continue; 48017651Speter if (tree[m].Len != (unsigned) bits) { 48117651Speter Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); 48217651Speter s->opt_len += ((long)bits - (long)tree[m].Len) 48317651Speter *(long)tree[m].Freq; 48417651Speter tree[m].Len = (ush)bits; 48517651Speter } 48617651Speter n--; 48717651Speter } 48817651Speter } 48917651Speter} 49017651Speter 49117651Speter/* =========================================================================== 49217651Speter * Generate the codes for a given tree and bit counts (which need not be 49317651Speter * optimal). 49417651Speter * IN assertion: the array bl_count contains the bit length statistics for 49517651Speter * the given tree and the field len is set for all tree elements. 49617651Speter * OUT assertion: the field code is set for all tree elements of non 49717651Speter * zero code length. 49817651Speter */ 49917651Speterlocal void gen_codes (tree, max_code, bl_count) 50017651Speter ct_data *tree; /* the tree to decorate */ 50117651Speter int max_code; /* largest code with non zero frequency */ 50217651Speter ushf *bl_count; /* number of codes at each bit length */ 50317651Speter{ 50417651Speter ush next_code[MAX_BITS+1]; /* next code value for each bit length */ 50517651Speter ush code = 0; /* running code value */ 50617651Speter int bits; /* bit index */ 50717651Speter int n; /* code index */ 50817651Speter 50917651Speter /* The distribution counts are first used to generate the code values 51017651Speter * without bit reversal. 51117651Speter */ 51217651Speter for (bits = 1; bits <= MAX_BITS; bits++) { 51317651Speter next_code[bits] = code = (code + bl_count[bits-1]) << 1; 51417651Speter } 51517651Speter /* Check that the bit counts in bl_count are consistent. The last code 51617651Speter * must be all ones. 51717651Speter */ 51817651Speter Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, 51917651Speter "inconsistent bit counts"); 52017651Speter Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); 52117651Speter 52217651Speter for (n = 0; n <= max_code; n++) { 52317651Speter int len = tree[n].Len; 52417651Speter if (len == 0) continue; 52517651Speter /* Now reverse the bits */ 52617651Speter tree[n].Code = bi_reverse(next_code[len]++, len); 52717651Speter 52817651Speter Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", 52917651Speter n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); 53017651Speter } 53117651Speter} 53217651Speter 53317651Speter/* =========================================================================== 53417651Speter * Construct one Huffman tree and assigns the code bit strings and lengths. 53517651Speter * Update the total bit length for the current block. 53617651Speter * IN assertion: the field freq is set for all tree elements. 53717651Speter * OUT assertions: the fields len and code are set to the optimal bit length 53817651Speter * and corresponding code. The length opt_len is updated; static_len is 53917651Speter * also updated if stree is not null. The field max_code is set. 54017651Speter */ 54117651Speterlocal void build_tree(s, desc) 54217651Speter deflate_state *s; 54317651Speter tree_desc *desc; /* the tree descriptor */ 54417651Speter{ 54517651Speter ct_data *tree = desc->dyn_tree; 54617651Speter ct_data *stree = desc->stat_desc->static_tree; 54717651Speter int elems = desc->stat_desc->elems; 54817651Speter int n, m; /* iterate over heap elements */ 54917651Speter int max_code = -1; /* largest code with non zero frequency */ 55017651Speter int node; /* new node being created */ 55117651Speter 55217651Speter /* Construct the initial heap, with least frequent element in 55317651Speter * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. 55417651Speter * heap[0] is not used. 55517651Speter */ 55617651Speter s->heap_len = 0, s->heap_max = HEAP_SIZE; 55717651Speter 55817651Speter for (n = 0; n < elems; n++) { 55917651Speter if (tree[n].Freq != 0) { 56017651Speter s->heap[++(s->heap_len)] = max_code = n; 56117651Speter s->depth[n] = 0; 56217651Speter } else { 56317651Speter tree[n].Len = 0; 56417651Speter } 56517651Speter } 56617651Speter 56717651Speter /* The pkzip format requires that at least one distance code exists, 56817651Speter * and that at least one bit should be sent even if there is only one 56917651Speter * possible code. So to avoid special checks later on we force at least 57017651Speter * two codes of non zero frequency. 57117651Speter */ 57217651Speter while (s->heap_len < 2) { 57317651Speter node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0); 57417651Speter tree[node].Freq = 1; 57517651Speter s->depth[node] = 0; 57617651Speter s->opt_len--; if (stree) s->static_len -= stree[node].Len; 57717651Speter /* node is 0 or 1 so it does not have extra bits */ 57817651Speter } 57917651Speter desc->max_code = max_code; 58017651Speter 58117651Speter /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, 58217651Speter * establish sub-heaps of increasing lengths: 58317651Speter */ 58417651Speter for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n); 58517651Speter 58617651Speter /* Construct the Huffman tree by repeatedly combining the least two 58717651Speter * frequent nodes. 58817651Speter */ 58917651Speter node = elems; /* next internal node of the tree */ 59017651Speter do { 59117651Speter pqremove(s, tree, n); /* n = node of least frequency */ 59217651Speter m = s->heap[SMALLEST]; /* m = node of next least frequency */ 59317651Speter 59417651Speter s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */ 59517651Speter s->heap[--(s->heap_max)] = m; 59617651Speter 59717651Speter /* Create a new node father of n and m */ 59817651Speter tree[node].Freq = tree[n].Freq + tree[m].Freq; 59917651Speter s->depth[node] = (uch) (MAX(s->depth[n], s->depth[m]) + 1); 60017651Speter tree[n].Dad = tree[m].Dad = (ush)node; 60117651Speter#ifdef DUMP_BL_TREE 60217651Speter if (tree == s->bl_tree) { 60317651Speter fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", 60417651Speter node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); 60517651Speter } 60617651Speter#endif 60717651Speter /* and insert the new node in the heap */ 60817651Speter s->heap[SMALLEST] = node++; 60917651Speter pqdownheap(s, tree, SMALLEST); 61017651Speter 61117651Speter } while (s->heap_len >= 2); 61217651Speter 61317651Speter s->heap[--(s->heap_max)] = s->heap[SMALLEST]; 61417651Speter 61517651Speter /* At this point, the fields freq and dad are set. We can now 61617651Speter * generate the bit lengths. 61717651Speter */ 61817651Speter gen_bitlen(s, (tree_desc *)desc); 61917651Speter 62017651Speter /* The field len is now set, we can generate the bit codes */ 62117651Speter gen_codes ((ct_data *)tree, max_code, s->bl_count); 62217651Speter} 62317651Speter 62417651Speter/* =========================================================================== 62517651Speter * Scan a literal or distance tree to determine the frequencies of the codes 62617651Speter * in the bit length tree. 62717651Speter */ 62817651Speterlocal void scan_tree (s, tree, max_code) 62917651Speter deflate_state *s; 63017651Speter ct_data *tree; /* the tree to be scanned */ 63117651Speter int max_code; /* and its largest code of non zero frequency */ 63217651Speter{ 63317651Speter int n; /* iterates over all tree elements */ 63417651Speter int prevlen = -1; /* last emitted length */ 63517651Speter int curlen; /* length of current code */ 63617651Speter int nextlen = tree[0].Len; /* length of next code */ 63717651Speter int count = 0; /* repeat count of the current code */ 63817651Speter int max_count = 7; /* max repeat count */ 63917651Speter int min_count = 4; /* min repeat count */ 64017651Speter 64117651Speter if (nextlen == 0) max_count = 138, min_count = 3; 64217651Speter tree[max_code+1].Len = (ush)0xffff; /* guard */ 64317651Speter 64417651Speter for (n = 0; n <= max_code; n++) { 64517651Speter curlen = nextlen; nextlen = tree[n+1].Len; 64617651Speter if (++count < max_count && curlen == nextlen) { 64717651Speter continue; 64817651Speter } else if (count < min_count) { 64917651Speter s->bl_tree[curlen].Freq += count; 65017651Speter } else if (curlen != 0) { 65117651Speter if (curlen != prevlen) s->bl_tree[curlen].Freq++; 65217651Speter s->bl_tree[REP_3_6].Freq++; 65317651Speter } else if (count <= 10) { 65417651Speter s->bl_tree[REPZ_3_10].Freq++; 65517651Speter } else { 65617651Speter s->bl_tree[REPZ_11_138].Freq++; 65717651Speter } 65817651Speter count = 0; prevlen = curlen; 65917651Speter if (nextlen == 0) { 66017651Speter max_count = 138, min_count = 3; 66117651Speter } else if (curlen == nextlen) { 66217651Speter max_count = 6, min_count = 3; 66317651Speter } else { 66417651Speter max_count = 7, min_count = 4; 66517651Speter } 66617651Speter } 66717651Speter} 66817651Speter 66917651Speter/* =========================================================================== 67017651Speter * Send a literal or distance tree in compressed form, using the codes in 67117651Speter * bl_tree. 67217651Speter */ 67317651Speterlocal void send_tree (s, tree, max_code) 67417651Speter deflate_state *s; 67517651Speter ct_data *tree; /* the tree to be scanned */ 67617651Speter int max_code; /* and its largest code of non zero frequency */ 67717651Speter{ 67817651Speter int n; /* iterates over all tree elements */ 67917651Speter int prevlen = -1; /* last emitted length */ 68017651Speter int curlen; /* length of current code */ 68117651Speter int nextlen = tree[0].Len; /* length of next code */ 68217651Speter int count = 0; /* repeat count of the current code */ 68317651Speter int max_count = 7; /* max repeat count */ 68417651Speter int min_count = 4; /* min repeat count */ 68517651Speter 68617651Speter /* tree[max_code+1].Len = -1; */ /* guard already set */ 68717651Speter if (nextlen == 0) max_count = 138, min_count = 3; 68817651Speter 68917651Speter for (n = 0; n <= max_code; n++) { 69017651Speter curlen = nextlen; nextlen = tree[n+1].Len; 69117651Speter if (++count < max_count && curlen == nextlen) { 69217651Speter continue; 69317651Speter } else if (count < min_count) { 69417651Speter do { send_code(s, curlen, s->bl_tree); } while (--count != 0); 69517651Speter 69617651Speter } else if (curlen != 0) { 69717651Speter if (curlen != prevlen) { 69817651Speter send_code(s, curlen, s->bl_tree); count--; 69917651Speter } 70017651Speter Assert(count >= 3 && count <= 6, " 3_6?"); 70117651Speter send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2); 70217651Speter 70317651Speter } else if (count <= 10) { 70417651Speter send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3); 70517651Speter 70617651Speter } else { 70717651Speter send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7); 70817651Speter } 70917651Speter count = 0; prevlen = curlen; 71017651Speter if (nextlen == 0) { 71117651Speter max_count = 138, min_count = 3; 71217651Speter } else if (curlen == nextlen) { 71317651Speter max_count = 6, min_count = 3; 71417651Speter } else { 71517651Speter max_count = 7, min_count = 4; 71617651Speter } 71717651Speter } 71817651Speter} 71917651Speter 72017651Speter/* =========================================================================== 72117651Speter * Construct the Huffman tree for the bit lengths and return the index in 72217651Speter * bl_order of the last bit length code to send. 72317651Speter */ 72417651Speterlocal int build_bl_tree(s) 72517651Speter deflate_state *s; 72617651Speter{ 72717651Speter int max_blindex; /* index of last bit length code of non zero freq */ 72817651Speter 72917651Speter /* Determine the bit length frequencies for literal and distance trees */ 73017651Speter scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code); 73117651Speter scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code); 73217651Speter 73317651Speter /* Build the bit length tree: */ 73417651Speter build_tree(s, (tree_desc *)(&(s->bl_desc))); 73517651Speter /* opt_len now includes the length of the tree representations, except 73617651Speter * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. 73717651Speter */ 73817651Speter 73917651Speter /* Determine the number of bit length codes to send. The pkzip format 74017651Speter * requires that at least 4 bit length codes be sent. (appnote.txt says 74117651Speter * 3 but the actual value used is 4.) 74217651Speter */ 74317651Speter for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { 74417651Speter if (s->bl_tree[bl_order[max_blindex]].Len != 0) break; 74517651Speter } 74617651Speter /* Update opt_len to include the bit length tree and counts */ 74717651Speter s->opt_len += 3*(max_blindex+1) + 5+5+4; 74817651Speter Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", 74917651Speter s->opt_len, s->static_len)); 75017651Speter 75117651Speter return max_blindex; 75217651Speter} 75317651Speter 75417651Speter/* =========================================================================== 75517651Speter * Send the header for a block using dynamic Huffman trees: the counts, the 75617651Speter * lengths of the bit length codes, the literal tree and the distance tree. 75717651Speter * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. 75817651Speter */ 75917651Speterlocal void send_all_trees(s, lcodes, dcodes, blcodes) 76017651Speter deflate_state *s; 76117651Speter int lcodes, dcodes, blcodes; /* number of codes for each tree */ 76217651Speter{ 76317651Speter int rank; /* index in bl_order */ 76417651Speter 76517651Speter Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); 76617651Speter Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, 76717651Speter "too many codes"); 76817651Speter Tracev((stderr, "\nbl counts: ")); 76917651Speter send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */ 77017651Speter send_bits(s, dcodes-1, 5); 77117651Speter send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */ 77217651Speter for (rank = 0; rank < blcodes; rank++) { 77317651Speter Tracev((stderr, "\nbl code %2d ", bl_order[rank])); 77417651Speter send_bits(s, s->bl_tree[bl_order[rank]].Len, 3); 77517651Speter } 77617651Speter Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent)); 77717651Speter 77817651Speter send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */ 77917651Speter Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent)); 78017651Speter 78117651Speter send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */ 78217651Speter Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent)); 78317651Speter} 78417651Speter 78517651Speter/* =========================================================================== 78617651Speter * Send a stored block 78717651Speter */ 78817651Spetervoid _tr_stored_block(s, buf, stored_len, eof) 78917651Speter deflate_state *s; 79017651Speter charf *buf; /* input block */ 79117651Speter ulg stored_len; /* length of input block */ 79217651Speter int eof; /* true if this is the last block for a file */ 79317651Speter{ 79417651Speter send_bits(s, (STORED_BLOCK<<1)+eof, 3); /* send block type */ 79517651Speter s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L; 79617651Speter s->compressed_len += (stored_len + 4) << 3; 79717651Speter 79817651Speter copy_block(s, buf, (unsigned)stored_len, 1); /* with header */ 79917651Speter} 80017651Speter 80117651Speter/* =========================================================================== 80217651Speter * Send one empty static block to give enough lookahead for inflate. 80317651Speter * This takes 10 bits, of which 7 may remain in the bit buffer. 80417651Speter * The current inflate code requires 9 bits of lookahead. If the 80517651Speter * last two codes for the previous block (real code plus EOB) were coded 80617651Speter * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode 80717651Speter * the last real code. In this case we send two empty static blocks instead 80817651Speter * of one. (There are no problems if the previous block is stored or fixed.) 80917651Speter * To simplify the code, we assume the worst case of last real code encoded 81017651Speter * on one bit only. 81117651Speter */ 81217651Spetervoid _tr_align(s) 81317651Speter deflate_state *s; 81417651Speter{ 81517651Speter send_bits(s, STATIC_TREES<<1, 3); 81617651Speter send_code(s, END_BLOCK, static_ltree); 81717651Speter s->compressed_len += 10L; /* 3 for block type, 7 for EOB */ 81817651Speter bi_flush(s); 81917651Speter /* Of the 10 bits for the empty block, we have already sent 82017651Speter * (10 - bi_valid) bits. The lookahead for the last real code (before 82117651Speter * the EOB of the previous block) was thus at least one plus the length 82217651Speter * of the EOB plus what we have just sent of the empty static block. 82317651Speter */ 82417651Speter if (1 + s->last_eob_len + 10 - s->bi_valid < 9) { 82517651Speter send_bits(s, STATIC_TREES<<1, 3); 82617651Speter send_code(s, END_BLOCK, static_ltree); 82717651Speter s->compressed_len += 10L; 82817651Speter bi_flush(s); 82917651Speter } 83017651Speter s->last_eob_len = 7; 83117651Speter} 83217651Speter 83317651Speter/* =========================================================================== 83417651Speter * Determine the best encoding for the current block: dynamic trees, static 83517651Speter * trees or store, and output the encoded block to the zip file. This function 83617651Speter * returns the total compressed length for the file so far. 83717651Speter */ 83817651Speterulg _tr_flush_block(s, buf, stored_len, eof) 83917651Speter deflate_state *s; 84017651Speter charf *buf; /* input block, or NULL if too old */ 84117651Speter ulg stored_len; /* length of input block */ 84217651Speter int eof; /* true if this is the last block for a file */ 84317651Speter{ 84417651Speter ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ 84517651Speter int max_blindex = 0; /* index of last bit length code of non zero freq */ 84617651Speter 84717651Speter /* Build the Huffman trees unless a stored block is forced */ 84817651Speter if (s->level > 0) { 84917651Speter 85017651Speter /* Check if the file is ascii or binary */ 85117651Speter if (s->data_type == Z_UNKNOWN) set_data_type(s); 85217651Speter 85317651Speter /* Construct the literal and distance trees */ 85417651Speter build_tree(s, (tree_desc *)(&(s->l_desc))); 85517651Speter Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len, 85617651Speter s->static_len)); 85717651Speter 85817651Speter build_tree(s, (tree_desc *)(&(s->d_desc))); 85917651Speter Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len, 86017651Speter s->static_len)); 86117651Speter /* At this point, opt_len and static_len are the total bit lengths of 86217651Speter * the compressed block data, excluding the tree representations. 86317651Speter */ 86417651Speter 86517651Speter /* Build the bit length tree for the above two trees, and get the index 86617651Speter * in bl_order of the last bit length code to send. 86717651Speter */ 86817651Speter max_blindex = build_bl_tree(s); 86917651Speter 87017651Speter /* Determine the best encoding. Compute first the block length in bytes*/ 87117651Speter opt_lenb = (s->opt_len+3+7)>>3; 87217651Speter static_lenb = (s->static_len+3+7)>>3; 87317651Speter 87417651Speter Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ", 87517651Speter opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, 87617651Speter s->last_lit)); 87717651Speter 87817651Speter if (static_lenb <= opt_lenb) opt_lenb = static_lenb; 87917651Speter 88017651Speter } else { 88117651Speter Assert(buf != (char*)0, "lost buf"); 88217651Speter opt_lenb = static_lenb = stored_len + 5; /* force a stored block */ 88317651Speter } 88417651Speter 88517651Speter /* If compression failed and this is the first and last block, 88617651Speter * and if the .zip file can be seeked (to rewrite the local header), 88717651Speter * the whole file is transformed into a stored file: 88817651Speter */ 88917651Speter#ifdef STORED_FILE_OK 89017651Speter# ifdef FORCE_STORED_FILE 89117651Speter if (eof && s->compressed_len == 0L) { /* force stored file */ 89217651Speter# else 89317651Speter if (stored_len <= opt_lenb && eof && s->compressed_len==0L && seekable()) { 89417651Speter# endif 89517651Speter /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ 89617651Speter if (buf == (charf*)0) error ("block vanished"); 89717651Speter 89817651Speter copy_block(buf, (unsigned)stored_len, 0); /* without header */ 89917651Speter s->compressed_len = stored_len << 3; 90017651Speter s->method = STORED; 90117651Speter } else 90217651Speter#endif /* STORED_FILE_OK */ 90317651Speter 90417651Speter#ifdef FORCE_STORED 90517651Speter if (buf != (char*)0) { /* force stored block */ 90617651Speter#else 90717651Speter if (stored_len+4 <= opt_lenb && buf != (char*)0) { 90817651Speter /* 4: two words for the lengths */ 90917651Speter#endif 91017651Speter /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. 91117651Speter * Otherwise we can't have processed more than WSIZE input bytes since 91217651Speter * the last block flush, because compression would have been 91317651Speter * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to 91417651Speter * transform a block into a stored block. 91517651Speter */ 91617651Speter _tr_stored_block(s, buf, stored_len, eof); 91717651Speter 91817651Speter#ifdef FORCE_STATIC 91917651Speter } else if (static_lenb >= 0) { /* force static trees */ 92017651Speter#else 92117651Speter } else if (static_lenb == opt_lenb) { 92217651Speter#endif 92317651Speter send_bits(s, (STATIC_TREES<<1)+eof, 3); 92417651Speter compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree); 92517651Speter s->compressed_len += 3 + s->static_len; 92617651Speter } else { 92717651Speter send_bits(s, (DYN_TREES<<1)+eof, 3); 92817651Speter send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1, 92917651Speter max_blindex+1); 93017651Speter compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree); 93117651Speter s->compressed_len += 3 + s->opt_len; 93217651Speter } 93317651Speter Assert (s->compressed_len == s->bits_sent, "bad compressed size"); 93417651Speter init_block(s); 93517651Speter 93617651Speter if (eof) { 93717651Speter bi_windup(s); 93817651Speter s->compressed_len += 7; /* align on byte boundary */ 93917651Speter } 94017651Speter Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3, 94117651Speter s->compressed_len-7*eof)); 94217651Speter 94317651Speter return s->compressed_len >> 3; 94417651Speter} 94517651Speter 94617651Speter/* =========================================================================== 94717651Speter * Save the match info and tally the frequency counts. Return true if 94817651Speter * the current block must be flushed. 94917651Speter */ 95017651Speterint _tr_tally (s, dist, lc) 95117651Speter deflate_state *s; 95217651Speter unsigned dist; /* distance of matched string */ 95317651Speter unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ 95417651Speter{ 95517651Speter s->d_buf[s->last_lit] = (ush)dist; 95617651Speter s->l_buf[s->last_lit++] = (uch)lc; 95717651Speter if (dist == 0) { 95817651Speter /* lc is the unmatched char */ 95917651Speter s->dyn_ltree[lc].Freq++; 96017651Speter } else { 96117651Speter s->matches++; 96217651Speter /* Here, lc is the match length - MIN_MATCH */ 96317651Speter dist--; /* dist = match distance - 1 */ 96417651Speter Assert((ush)dist < (ush)MAX_DIST(s) && 96517651Speter (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && 96617651Speter (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match"); 96717651Speter 96817651Speter s->dyn_ltree[length_code[lc]+LITERALS+1].Freq++; 96917651Speter s->dyn_dtree[d_code(dist)].Freq++; 97017651Speter } 97117651Speter 97217651Speter /* Try to guess if it is profitable to stop the current block here */ 97317651Speter if (s->level > 2 && (s->last_lit & 0xfff) == 0) { 97417651Speter /* Compute an upper bound for the compressed length */ 97517651Speter ulg out_length = (ulg)s->last_lit*8L; 97617651Speter ulg in_length = (ulg)((long)s->strstart - s->block_start); 97717651Speter int dcode; 97817651Speter for (dcode = 0; dcode < D_CODES; dcode++) { 97917651Speter out_length += (ulg)s->dyn_dtree[dcode].Freq * 98017651Speter (5L+extra_dbits[dcode]); 98117651Speter } 98217651Speter out_length >>= 3; 98317651Speter Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ", 98417651Speter s->last_lit, in_length, out_length, 98517651Speter 100L - out_length*100L/in_length)); 98617651Speter if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1; 98717651Speter } 98817651Speter return (s->last_lit == s->lit_bufsize-1); 98917651Speter /* We avoid equality with lit_bufsize because of wraparound at 64K 99017651Speter * on 16 bit machines and because stored blocks are restricted to 99117651Speter * 64K-1 bytes. 99217651Speter */ 99317651Speter} 99417651Speter 99517651Speter/* =========================================================================== 99617651Speter * Send the block data compressed using the given Huffman trees 99717651Speter */ 99817651Speterlocal void compress_block(s, ltree, dtree) 99917651Speter deflate_state *s; 100017651Speter ct_data *ltree; /* literal tree */ 100117651Speter ct_data *dtree; /* distance tree */ 100217651Speter{ 100317651Speter unsigned dist; /* distance of matched string */ 100417651Speter int lc; /* match length or unmatched char (if dist == 0) */ 100517651Speter unsigned lx = 0; /* running index in l_buf */ 100617651Speter unsigned code; /* the code to send */ 100717651Speter int extra; /* number of extra bits to send */ 100817651Speter 100917651Speter if (s->last_lit != 0) do { 101017651Speter dist = s->d_buf[lx]; 101117651Speter lc = s->l_buf[lx++]; 101217651Speter if (dist == 0) { 101317651Speter send_code(s, lc, ltree); /* send a literal byte */ 101417651Speter Tracecv(isgraph(lc), (stderr," '%c' ", lc)); 101517651Speter } else { 101617651Speter /* Here, lc is the match length - MIN_MATCH */ 101717651Speter code = length_code[lc]; 101817651Speter send_code(s, code+LITERALS+1, ltree); /* send the length code */ 101917651Speter extra = extra_lbits[code]; 102017651Speter if (extra != 0) { 102117651Speter lc -= base_length[code]; 102217651Speter send_bits(s, lc, extra); /* send the extra length bits */ 102317651Speter } 102417651Speter dist--; /* dist is now the match distance - 1 */ 102517651Speter code = d_code(dist); 102617651Speter Assert (code < D_CODES, "bad d_code"); 102717651Speter 102817651Speter send_code(s, code, dtree); /* send the distance code */ 102917651Speter extra = extra_dbits[code]; 103017651Speter if (extra != 0) { 103117651Speter dist -= base_dist[code]; 103217651Speter send_bits(s, dist, extra); /* send the extra distance bits */ 103317651Speter } 103417651Speter } /* literal or match pair ? */ 103517651Speter 103617651Speter /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */ 103717651Speter Assert(s->pending < s->lit_bufsize + 2*lx, "pendingBuf overflow"); 103817651Speter 103917651Speter } while (lx < s->last_lit); 104017651Speter 104117651Speter send_code(s, END_BLOCK, ltree); 104217651Speter s->last_eob_len = ltree[END_BLOCK].Len; 104317651Speter} 104417651Speter 104517651Speter/* =========================================================================== 104617651Speter * Set the data type to ASCII or BINARY, using a crude approximation: 104717651Speter * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise. 104817651Speter * IN assertion: the fields freq of dyn_ltree are set and the total of all 104917651Speter * frequencies does not exceed 64K (to fit in an int on 16 bit machines). 105017651Speter */ 105117651Speterlocal void set_data_type(s) 105217651Speter deflate_state *s; 105317651Speter{ 105417651Speter int n = 0; 105517651Speter unsigned ascii_freq = 0; 105617651Speter unsigned bin_freq = 0; 105717651Speter while (n < 7) bin_freq += s->dyn_ltree[n++].Freq; 105817651Speter while (n < 128) ascii_freq += s->dyn_ltree[n++].Freq; 105917651Speter while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq; 106017651Speter s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? Z_BINARY : Z_ASCII); 106117651Speter} 106217651Speter 106317651Speter/* =========================================================================== 106417651Speter * Reverse the first len bits of a code, using straightforward code (a faster 106517651Speter * method would use a table) 106617651Speter * IN assertion: 1 <= len <= 15 106717651Speter */ 106817651Speterlocal unsigned bi_reverse(code, len) 106917651Speter unsigned code; /* the value to invert */ 107017651Speter int len; /* its bit length */ 107117651Speter{ 107217651Speter register unsigned res = 0; 107317651Speter do { 107417651Speter res |= code & 1; 107517651Speter code >>= 1, res <<= 1; 107617651Speter } while (--len > 0); 107717651Speter return res >> 1; 107817651Speter} 107917651Speter 108017651Speter/* =========================================================================== 108117651Speter * Flush the bit buffer, keeping at most 7 bits in it. 108217651Speter */ 108317651Speterlocal void bi_flush(s) 108417651Speter deflate_state *s; 108517651Speter{ 108617651Speter if (s->bi_valid == 16) { 108717651Speter put_short(s, s->bi_buf); 108817651Speter s->bi_buf = 0; 108917651Speter s->bi_valid = 0; 109017651Speter } else if (s->bi_valid >= 8) { 109117651Speter put_byte(s, (Byte)s->bi_buf); 109217651Speter s->bi_buf >>= 8; 109317651Speter s->bi_valid -= 8; 109417651Speter } 109517651Speter} 109617651Speter 109717651Speter/* =========================================================================== 109817651Speter * Flush the bit buffer and align the output on a byte boundary 109917651Speter */ 110017651Speterlocal void bi_windup(s) 110117651Speter deflate_state *s; 110217651Speter{ 110317651Speter if (s->bi_valid > 8) { 110417651Speter put_short(s, s->bi_buf); 110517651Speter } else if (s->bi_valid > 0) { 110617651Speter put_byte(s, (Byte)s->bi_buf); 110717651Speter } 110817651Speter s->bi_buf = 0; 110917651Speter s->bi_valid = 0; 111017651Speter#ifdef DEBUG 111117651Speter s->bits_sent = (s->bits_sent+7) & ~7; 111217651Speter#endif 111317651Speter} 111417651Speter 111517651Speter/* =========================================================================== 111617651Speter * Copy a stored block, storing first the length and its 111717651Speter * one's complement if requested. 111817651Speter */ 111917651Speterlocal void copy_block(s, buf, len, header) 112017651Speter deflate_state *s; 112117651Speter charf *buf; /* the input data */ 112217651Speter unsigned len; /* its length */ 112317651Speter int header; /* true if block header must be written */ 112417651Speter{ 112517651Speter bi_windup(s); /* align on byte boundary */ 112617651Speter s->last_eob_len = 8; /* enough lookahead for inflate */ 112717651Speter 112817651Speter if (header) { 112917651Speter put_short(s, (ush)len); 113017651Speter put_short(s, (ush)~len); 113117651Speter#ifdef DEBUG 113217651Speter s->bits_sent += 2*16; 113317651Speter#endif 113417651Speter } 113517651Speter#ifdef DEBUG 113617651Speter s->bits_sent += (ulg)len<<3; 113717651Speter#endif 113817651Speter while (len--) { 113917651Speter put_byte(s, *buf++); 114017651Speter } 114117651Speter} 1142