vrshoot

diff libs/zlib/trees.c @ 0:b2f14e535253

initial commit
author John Tsiombikas <nuclear@member.fsf.org>
date Sat, 01 Feb 2014 19:58:19 +0200
parents
children
line diff
     1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/libs/zlib/trees.c	Sat Feb 01 19:58:19 2014 +0200
     1.3 @@ -0,0 +1,1219 @@
     1.4 +/* trees.c -- output deflated data using Huffman coding
     1.5 + * Copyright (C) 1995-2005 Jean-loup Gailly
     1.6 + * For conditions of distribution and use, see copyright notice in zlib.h
     1.7 + */
     1.8 +
     1.9 +/*
    1.10 + *  ALGORITHM
    1.11 + *
    1.12 + *      The "deflation" process uses several Huffman trees. The more
    1.13 + *      common source values are represented by shorter bit sequences.
    1.14 + *
    1.15 + *      Each code tree is stored in a compressed form which is itself
    1.16 + * a Huffman encoding of the lengths of all the code strings (in
    1.17 + * ascending order by source values).  The actual code strings are
    1.18 + * reconstructed from the lengths in the inflate process, as described
    1.19 + * in the deflate specification.
    1.20 + *
    1.21 + *  REFERENCES
    1.22 + *
    1.23 + *      Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
    1.24 + *      Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
    1.25 + *
    1.26 + *      Storer, James A.
    1.27 + *          Data Compression:  Methods and Theory, pp. 49-50.
    1.28 + *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
    1.29 + *
    1.30 + *      Sedgewick, R.
    1.31 + *          Algorithms, p290.
    1.32 + *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
    1.33 + */
    1.34 +
    1.35 +/* @(#) $Id$ */
    1.36 +
    1.37 +/* #define GEN_TREES_H */
    1.38 +
    1.39 +#include "deflate.h"
    1.40 +
    1.41 +#ifdef DEBUG
    1.42 +#  include <ctype.h>
    1.43 +#endif
    1.44 +
    1.45 +/* ===========================================================================
    1.46 + * Constants
    1.47 + */
    1.48 +
    1.49 +#define MAX_BL_BITS 7
    1.50 +/* Bit length codes must not exceed MAX_BL_BITS bits */
    1.51 +
    1.52 +#define END_BLOCK 256
    1.53 +/* end of block literal code */
    1.54 +
    1.55 +#define REP_3_6      16
    1.56 +/* repeat previous bit length 3-6 times (2 bits of repeat count) */
    1.57 +
    1.58 +#define REPZ_3_10    17
    1.59 +/* repeat a zero length 3-10 times  (3 bits of repeat count) */
    1.60 +
    1.61 +#define REPZ_11_138  18
    1.62 +/* repeat a zero length 11-138 times  (7 bits of repeat count) */
    1.63 +
    1.64 +local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
    1.65 +   = {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};
    1.66 +
    1.67 +local const int extra_dbits[D_CODES] /* extra bits for each distance code */
    1.68 +   = {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};
    1.69 +
    1.70 +local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
    1.71 +   = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
    1.72 +
    1.73 +local const uch bl_order[BL_CODES]
    1.74 +   = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
    1.75 +/* The lengths of the bit length codes are sent in order of decreasing
    1.76 + * probability, to avoid transmitting the lengths for unused bit length codes.
    1.77 + */
    1.78 +
    1.79 +#define Buf_size (8 * 2*sizeof(char))
    1.80 +/* Number of bits used within bi_buf. (bi_buf might be implemented on
    1.81 + * more than 16 bits on some systems.)
    1.82 + */
    1.83 +
    1.84 +/* ===========================================================================
    1.85 + * Local data. These are initialized only once.
    1.86 + */
    1.87 +
    1.88 +#define DIST_CODE_LEN  512 /* see definition of array dist_code below */
    1.89 +
    1.90 +#if defined(GEN_TREES_H) || !defined(STDC)
    1.91 +/* non ANSI compilers may not accept trees.h */
    1.92 +
    1.93 +local ct_data static_ltree[L_CODES+2];
    1.94 +/* The static literal tree. Since the bit lengths are imposed, there is no
    1.95 + * need for the L_CODES extra codes used during heap construction. However
    1.96 + * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
    1.97 + * below).
    1.98 + */
    1.99 +
   1.100 +local ct_data static_dtree[D_CODES];
   1.101 +/* The static distance tree. (Actually a trivial tree since all codes use
   1.102 + * 5 bits.)
   1.103 + */
   1.104 +
   1.105 +uch _dist_code[DIST_CODE_LEN];
   1.106 +/* Distance codes. The first 256 values correspond to the distances
   1.107 + * 3 .. 258, the last 256 values correspond to the top 8 bits of
   1.108 + * the 15 bit distances.
   1.109 + */
   1.110 +
   1.111 +uch _length_code[MAX_MATCH-MIN_MATCH+1];
   1.112 +/* length code for each normalized match length (0 == MIN_MATCH) */
   1.113 +
   1.114 +local int base_length[LENGTH_CODES];
   1.115 +/* First normalized length for each code (0 = MIN_MATCH) */
   1.116 +
   1.117 +local int base_dist[D_CODES];
   1.118 +/* First normalized distance for each code (0 = distance of 1) */
   1.119 +
   1.120 +#else
   1.121 +#  include "trees.h"
   1.122 +#endif /* GEN_TREES_H */
   1.123 +
   1.124 +struct static_tree_desc_s {
   1.125 +    const ct_data *static_tree;  /* static tree or NULL */
   1.126 +    const intf *extra_bits;      /* extra bits for each code or NULL */
   1.127 +    int     extra_base;          /* base index for extra_bits */
   1.128 +    int     elems;               /* max number of elements in the tree */
   1.129 +    int     max_length;          /* max bit length for the codes */
   1.130 +};
   1.131 +
   1.132 +local static_tree_desc  static_l_desc =
   1.133 +{static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
   1.134 +
   1.135 +local static_tree_desc  static_d_desc =
   1.136 +{static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};
   1.137 +
   1.138 +local static_tree_desc  static_bl_desc =
   1.139 +{(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
   1.140 +
   1.141 +/* ===========================================================================
   1.142 + * Local (static) routines in this file.
   1.143 + */
   1.144 +
   1.145 +local void tr_static_init OF((void));
   1.146 +local void init_block     OF((deflate_state *s));
   1.147 +local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));
   1.148 +local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));
   1.149 +local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));
   1.150 +local void build_tree     OF((deflate_state *s, tree_desc *desc));
   1.151 +local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));
   1.152 +local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));
   1.153 +local int  build_bl_tree  OF((deflate_state *s));
   1.154 +local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
   1.155 +                              int blcodes));
   1.156 +local void compress_block OF((deflate_state *s, ct_data *ltree,
   1.157 +                              ct_data *dtree));
   1.158 +local void set_data_type  OF((deflate_state *s));
   1.159 +local unsigned bi_reverse OF((unsigned value, int length));
   1.160 +local void bi_windup      OF((deflate_state *s));
   1.161 +local void bi_flush       OF((deflate_state *s));
   1.162 +local void copy_block     OF((deflate_state *s, charf *buf, unsigned len,
   1.163 +                              int header));
   1.164 +
   1.165 +#ifdef GEN_TREES_H
   1.166 +local void gen_trees_header OF((void));
   1.167 +#endif
   1.168 +
   1.169 +#ifndef DEBUG
   1.170 +#  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
   1.171 +   /* Send a code of the given tree. c and tree must not have side effects */
   1.172 +
   1.173 +#else /* DEBUG */
   1.174 +#  define send_code(s, c, tree) \
   1.175 +     { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
   1.176 +       send_bits(s, tree[c].Code, tree[c].Len); }
   1.177 +#endif
   1.178 +
   1.179 +/* ===========================================================================
   1.180 + * Output a short LSB first on the stream.
   1.181 + * IN assertion: there is enough room in pendingBuf.
   1.182 + */
   1.183 +#define put_short(s, w) { \
   1.184 +    put_byte(s, (uch)((w) & 0xff)); \
   1.185 +    put_byte(s, (uch)((ush)(w) >> 8)); \
   1.186 +}
   1.187 +
   1.188 +/* ===========================================================================
   1.189 + * Send a value on a given number of bits.
   1.190 + * IN assertion: length <= 16 and value fits in length bits.
   1.191 + */
   1.192 +#ifdef DEBUG
   1.193 +local void send_bits      OF((deflate_state *s, int value, int length));
   1.194 +
   1.195 +local void send_bits(s, value, length)
   1.196 +    deflate_state *s;
   1.197 +    int value;  /* value to send */
   1.198 +    int length; /* number of bits */
   1.199 +{
   1.200 +    Tracevv((stderr," l %2d v %4x ", length, value));
   1.201 +    Assert(length > 0 && length <= 15, "invalid length");
   1.202 +    s->bits_sent += (ulg)length;
   1.203 +
   1.204 +    /* If not enough room in bi_buf, use (valid) bits from bi_buf and
   1.205 +     * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
   1.206 +     * unused bits in value.
   1.207 +     */
   1.208 +    if (s->bi_valid > (int)Buf_size - length) {
   1.209 +        s->bi_buf |= (value << s->bi_valid);
   1.210 +        put_short(s, s->bi_buf);
   1.211 +        s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
   1.212 +        s->bi_valid += length - Buf_size;
   1.213 +    } else {
   1.214 +        s->bi_buf |= value << s->bi_valid;
   1.215 +        s->bi_valid += length;
   1.216 +    }
   1.217 +}
   1.218 +#else /* !DEBUG */
   1.219 +
   1.220 +#define send_bits(s, value, length) \
   1.221 +{ int len = length;\
   1.222 +  if (s->bi_valid > (int)Buf_size - len) {\
   1.223 +    int val = value;\
   1.224 +    s->bi_buf |= (val << s->bi_valid);\
   1.225 +    put_short(s, s->bi_buf);\
   1.226 +    s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
   1.227 +    s->bi_valid += len - Buf_size;\
   1.228 +  } else {\
   1.229 +    s->bi_buf |= (value) << s->bi_valid;\
   1.230 +    s->bi_valid += len;\
   1.231 +  }\
   1.232 +}
   1.233 +#endif /* DEBUG */
   1.234 +
   1.235 +
   1.236 +/* the arguments must not have side effects */
   1.237 +
   1.238 +/* ===========================================================================
   1.239 + * Initialize the various 'constant' tables.
   1.240 + */
   1.241 +local void tr_static_init()
   1.242 +{
   1.243 +#if defined(GEN_TREES_H) || !defined(STDC)
   1.244 +    static int static_init_done = 0;
   1.245 +    int n;        /* iterates over tree elements */
   1.246 +    int bits;     /* bit counter */
   1.247 +    int length;   /* length value */
   1.248 +    int code;     /* code value */
   1.249 +    int dist;     /* distance index */
   1.250 +    ush bl_count[MAX_BITS+1];
   1.251 +    /* number of codes at each bit length for an optimal tree */
   1.252 +
   1.253 +    if (static_init_done) return;
   1.254 +
   1.255 +    /* For some embedded targets, global variables are not initialized: */
   1.256 +    static_l_desc.static_tree = static_ltree;
   1.257 +    static_l_desc.extra_bits = extra_lbits;
   1.258 +    static_d_desc.static_tree = static_dtree;
   1.259 +    static_d_desc.extra_bits = extra_dbits;
   1.260 +    static_bl_desc.extra_bits = extra_blbits;
   1.261 +
   1.262 +    /* Initialize the mapping length (0..255) -> length code (0..28) */
   1.263 +    length = 0;
   1.264 +    for (code = 0; code < LENGTH_CODES-1; code++) {
   1.265 +        base_length[code] = length;
   1.266 +        for (n = 0; n < (1<<extra_lbits[code]); n++) {
   1.267 +            _length_code[length++] = (uch)code;
   1.268 +        }
   1.269 +    }
   1.270 +    Assert (length == 256, "tr_static_init: length != 256");
   1.271 +    /* Note that the length 255 (match length 258) can be represented
   1.272 +     * in two different ways: code 284 + 5 bits or code 285, so we
   1.273 +     * overwrite length_code[255] to use the best encoding:
   1.274 +     */
   1.275 +    _length_code[length-1] = (uch)code;
   1.276 +
   1.277 +    /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
   1.278 +    dist = 0;
   1.279 +    for (code = 0 ; code < 16; code++) {
   1.280 +        base_dist[code] = dist;
   1.281 +        for (n = 0; n < (1<<extra_dbits[code]); n++) {
   1.282 +            _dist_code[dist++] = (uch)code;
   1.283 +        }
   1.284 +    }
   1.285 +    Assert (dist == 256, "tr_static_init: dist != 256");
   1.286 +    dist >>= 7; /* from now on, all distances are divided by 128 */
   1.287 +    for ( ; code < D_CODES; code++) {
   1.288 +        base_dist[code] = dist << 7;
   1.289 +        for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
   1.290 +            _dist_code[256 + dist++] = (uch)code;
   1.291 +        }
   1.292 +    }
   1.293 +    Assert (dist == 256, "tr_static_init: 256+dist != 512");
   1.294 +
   1.295 +    /* Construct the codes of the static literal tree */
   1.296 +    for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
   1.297 +    n = 0;
   1.298 +    while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
   1.299 +    while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
   1.300 +    while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
   1.301 +    while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
   1.302 +    /* Codes 286 and 287 do not exist, but we must include them in the
   1.303 +     * tree construction to get a canonical Huffman tree (longest code
   1.304 +     * all ones)
   1.305 +     */
   1.306 +    gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
   1.307 +
   1.308 +    /* The static distance tree is trivial: */
   1.309 +    for (n = 0; n < D_CODES; n++) {
   1.310 +        static_dtree[n].Len = 5;
   1.311 +        static_dtree[n].Code = bi_reverse((unsigned)n, 5);
   1.312 +    }
   1.313 +    static_init_done = 1;
   1.314 +
   1.315 +#  ifdef GEN_TREES_H
   1.316 +    gen_trees_header();
   1.317 +#  endif
   1.318 +#endif /* defined(GEN_TREES_H) || !defined(STDC) */
   1.319 +}
   1.320 +
   1.321 +/* ===========================================================================
   1.322 + * Genererate the file trees.h describing the static trees.
   1.323 + */
   1.324 +#ifdef GEN_TREES_H
   1.325 +#  ifndef DEBUG
   1.326 +#    include <stdio.h>
   1.327 +#  endif
   1.328 +
   1.329 +#  define SEPARATOR(i, last, width) \
   1.330 +      ((i) == (last)? "\n};\n\n" :    \
   1.331 +       ((i) % (width) == (width)-1 ? ",\n" : ", "))
   1.332 +
   1.333 +void gen_trees_header()
   1.334 +{
   1.335 +    FILE *header = fopen("trees.h", "w");
   1.336 +    int i;
   1.337 +
   1.338 +    Assert (header != NULL, "Can't open trees.h");
   1.339 +    fprintf(header,
   1.340 +            "/* header created automatically with -DGEN_TREES_H */\n\n");
   1.341 +
   1.342 +    fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
   1.343 +    for (i = 0; i < L_CODES+2; i++) {
   1.344 +        fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
   1.345 +                static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
   1.346 +    }
   1.347 +
   1.348 +    fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
   1.349 +    for (i = 0; i < D_CODES; i++) {
   1.350 +        fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
   1.351 +                static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
   1.352 +    }
   1.353 +
   1.354 +    fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n");
   1.355 +    for (i = 0; i < DIST_CODE_LEN; i++) {
   1.356 +        fprintf(header, "%2u%s", _dist_code[i],
   1.357 +                SEPARATOR(i, DIST_CODE_LEN-1, 20));
   1.358 +    }
   1.359 +
   1.360 +    fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
   1.361 +    for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
   1.362 +        fprintf(header, "%2u%s", _length_code[i],
   1.363 +                SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
   1.364 +    }
   1.365 +
   1.366 +    fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
   1.367 +    for (i = 0; i < LENGTH_CODES; i++) {
   1.368 +        fprintf(header, "%1u%s", base_length[i],
   1.369 +                SEPARATOR(i, LENGTH_CODES-1, 20));
   1.370 +    }
   1.371 +
   1.372 +    fprintf(header, "local const int base_dist[D_CODES] = {\n");
   1.373 +    for (i = 0; i < D_CODES; i++) {
   1.374 +        fprintf(header, "%5u%s", base_dist[i],
   1.375 +                SEPARATOR(i, D_CODES-1, 10));
   1.376 +    }
   1.377 +
   1.378 +    fclose(header);
   1.379 +}
   1.380 +#endif /* GEN_TREES_H */
   1.381 +
   1.382 +/* ===========================================================================
   1.383 + * Initialize the tree data structures for a new zlib stream.
   1.384 + */
   1.385 +void _tr_init(s)
   1.386 +    deflate_state *s;
   1.387 +{
   1.388 +    tr_static_init();
   1.389 +
   1.390 +    s->l_desc.dyn_tree = s->dyn_ltree;
   1.391 +    s->l_desc.stat_desc = &static_l_desc;
   1.392 +
   1.393 +    s->d_desc.dyn_tree = s->dyn_dtree;
   1.394 +    s->d_desc.stat_desc = &static_d_desc;
   1.395 +
   1.396 +    s->bl_desc.dyn_tree = s->bl_tree;
   1.397 +    s->bl_desc.stat_desc = &static_bl_desc;
   1.398 +
   1.399 +    s->bi_buf = 0;
   1.400 +    s->bi_valid = 0;
   1.401 +    s->last_eob_len = 8; /* enough lookahead for inflate */
   1.402 +#ifdef DEBUG
   1.403 +    s->compressed_len = 0L;
   1.404 +    s->bits_sent = 0L;
   1.405 +#endif
   1.406 +
   1.407 +    /* Initialize the first block of the first file: */
   1.408 +    init_block(s);
   1.409 +}
   1.410 +
   1.411 +/* ===========================================================================
   1.412 + * Initialize a new block.
   1.413 + */
   1.414 +local void init_block(s)
   1.415 +    deflate_state *s;
   1.416 +{
   1.417 +    int n; /* iterates over tree elements */
   1.418 +
   1.419 +    /* Initialize the trees. */
   1.420 +    for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
   1.421 +    for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
   1.422 +    for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
   1.423 +
   1.424 +    s->dyn_ltree[END_BLOCK].Freq = 1;
   1.425 +    s->opt_len = s->static_len = 0L;
   1.426 +    s->last_lit = s->matches = 0;
   1.427 +}
   1.428 +
   1.429 +#define SMALLEST 1
   1.430 +/* Index within the heap array of least frequent node in the Huffman tree */
   1.431 +
   1.432 +
   1.433 +/* ===========================================================================
   1.434 + * Remove the smallest element from the heap and recreate the heap with
   1.435 + * one less element. Updates heap and heap_len.
   1.436 + */
   1.437 +#define pqremove(s, tree, top) \
   1.438 +{\
   1.439 +    top = s->heap[SMALLEST]; \
   1.440 +    s->heap[SMALLEST] = s->heap[s->heap_len--]; \
   1.441 +    pqdownheap(s, tree, SMALLEST); \
   1.442 +}
   1.443 +
   1.444 +/* ===========================================================================
   1.445 + * Compares to subtrees, using the tree depth as tie breaker when
   1.446 + * the subtrees have equal frequency. This minimizes the worst case length.
   1.447 + */
   1.448 +#define smaller(tree, n, m, depth) \
   1.449 +   (tree[n].Freq < tree[m].Freq || \
   1.450 +   (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
   1.451 +
   1.452 +/* ===========================================================================
   1.453 + * Restore the heap property by moving down the tree starting at node k,
   1.454 + * exchanging a node with the smallest of its two sons if necessary, stopping
   1.455 + * when the heap property is re-established (each father smaller than its
   1.456 + * two sons).
   1.457 + */
   1.458 +local void pqdownheap(s, tree, k)
   1.459 +    deflate_state *s;
   1.460 +    ct_data *tree;  /* the tree to restore */
   1.461 +    int k;               /* node to move down */
   1.462 +{
   1.463 +    int v = s->heap[k];
   1.464 +    int j = k << 1;  /* left son of k */
   1.465 +    while (j <= s->heap_len) {
   1.466 +        /* Set j to the smallest of the two sons: */
   1.467 +        if (j < s->heap_len &&
   1.468 +            smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
   1.469 +            j++;
   1.470 +        }
   1.471 +        /* Exit if v is smaller than both sons */
   1.472 +        if (smaller(tree, v, s->heap[j], s->depth)) break;
   1.473 +
   1.474 +        /* Exchange v with the smallest son */
   1.475 +        s->heap[k] = s->heap[j];  k = j;
   1.476 +
   1.477 +        /* And continue down the tree, setting j to the left son of k */
   1.478 +        j <<= 1;
   1.479 +    }
   1.480 +    s->heap[k] = v;
   1.481 +}
   1.482 +
   1.483 +/* ===========================================================================
   1.484 + * Compute the optimal bit lengths for a tree and update the total bit length
   1.485 + * for the current block.
   1.486 + * IN assertion: the fields freq and dad are set, heap[heap_max] and
   1.487 + *    above are the tree nodes sorted by increasing frequency.
   1.488 + * OUT assertions: the field len is set to the optimal bit length, the
   1.489 + *     array bl_count contains the frequencies for each bit length.
   1.490 + *     The length opt_len is updated; static_len is also updated if stree is
   1.491 + *     not null.
   1.492 + */
   1.493 +local void gen_bitlen(s, desc)
   1.494 +    deflate_state *s;
   1.495 +    tree_desc *desc;    /* the tree descriptor */
   1.496 +{
   1.497 +    ct_data *tree        = desc->dyn_tree;
   1.498 +    int max_code         = desc->max_code;
   1.499 +    const ct_data *stree = desc->stat_desc->static_tree;
   1.500 +    const intf *extra    = desc->stat_desc->extra_bits;
   1.501 +    int base             = desc->stat_desc->extra_base;
   1.502 +    int max_length       = desc->stat_desc->max_length;
   1.503 +    int h;              /* heap index */
   1.504 +    int n, m;           /* iterate over the tree elements */
   1.505 +    int bits;           /* bit length */
   1.506 +    int xbits;          /* extra bits */
   1.507 +    ush f;              /* frequency */
   1.508 +    int overflow = 0;   /* number of elements with bit length too large */
   1.509 +
   1.510 +    for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
   1.511 +
   1.512 +    /* In a first pass, compute the optimal bit lengths (which may
   1.513 +     * overflow in the case of the bit length tree).
   1.514 +     */
   1.515 +    tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
   1.516 +
   1.517 +    for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
   1.518 +        n = s->heap[h];
   1.519 +        bits = tree[tree[n].Dad].Len + 1;
   1.520 +        if (bits > max_length) bits = max_length, overflow++;
   1.521 +        tree[n].Len = (ush)bits;
   1.522 +        /* We overwrite tree[n].Dad which is no longer needed */
   1.523 +
   1.524 +        if (n > max_code) continue; /* not a leaf node */
   1.525 +
   1.526 +        s->bl_count[bits]++;
   1.527 +        xbits = 0;
   1.528 +        if (n >= base) xbits = extra[n-base];
   1.529 +        f = tree[n].Freq;
   1.530 +        s->opt_len += (ulg)f * (bits + xbits);
   1.531 +        if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
   1.532 +    }
   1.533 +    if (overflow == 0) return;
   1.534 +
   1.535 +    Trace((stderr,"\nbit length overflow\n"));
   1.536 +    /* This happens for example on obj2 and pic of the Calgary corpus */
   1.537 +
   1.538 +    /* Find the first bit length which could increase: */
   1.539 +    do {
   1.540 +        bits = max_length-1;
   1.541 +        while (s->bl_count[bits] == 0) bits--;
   1.542 +        s->bl_count[bits]--;      /* move one leaf down the tree */
   1.543 +        s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
   1.544 +        s->bl_count[max_length]--;
   1.545 +        /* The brother of the overflow item also moves one step up,
   1.546 +         * but this does not affect bl_count[max_length]
   1.547 +         */
   1.548 +        overflow -= 2;
   1.549 +    } while (overflow > 0);
   1.550 +
   1.551 +    /* Now recompute all bit lengths, scanning in increasing frequency.
   1.552 +     * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
   1.553 +     * lengths instead of fixing only the wrong ones. This idea is taken
   1.554 +     * from 'ar' written by Haruhiko Okumura.)
   1.555 +     */
   1.556 +    for (bits = max_length; bits != 0; bits--) {
   1.557 +        n = s->bl_count[bits];
   1.558 +        while (n != 0) {
   1.559 +            m = s->heap[--h];
   1.560 +            if (m > max_code) continue;
   1.561 +            if ((unsigned) tree[m].Len != (unsigned) bits) {
   1.562 +                Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
   1.563 +                s->opt_len += ((long)bits - (long)tree[m].Len)
   1.564 +                              *(long)tree[m].Freq;
   1.565 +                tree[m].Len = (ush)bits;
   1.566 +            }
   1.567 +            n--;
   1.568 +        }
   1.569 +    }
   1.570 +}
   1.571 +
   1.572 +/* ===========================================================================
   1.573 + * Generate the codes for a given tree and bit counts (which need not be
   1.574 + * optimal).
   1.575 + * IN assertion: the array bl_count contains the bit length statistics for
   1.576 + * the given tree and the field len is set for all tree elements.
   1.577 + * OUT assertion: the field code is set for all tree elements of non
   1.578 + *     zero code length.
   1.579 + */
   1.580 +local void gen_codes (tree, max_code, bl_count)
   1.581 +    ct_data *tree;             /* the tree to decorate */
   1.582 +    int max_code;              /* largest code with non zero frequency */
   1.583 +    ushf *bl_count;            /* number of codes at each bit length */
   1.584 +{
   1.585 +    ush next_code[MAX_BITS+1]; /* next code value for each bit length */
   1.586 +    ush code = 0;              /* running code value */
   1.587 +    int bits;                  /* bit index */
   1.588 +    int n;                     /* code index */
   1.589 +
   1.590 +    /* The distribution counts are first used to generate the code values
   1.591 +     * without bit reversal.
   1.592 +     */
   1.593 +    for (bits = 1; bits <= MAX_BITS; bits++) {
   1.594 +        next_code[bits] = code = (code + bl_count[bits-1]) << 1;
   1.595 +    }
   1.596 +    /* Check that the bit counts in bl_count are consistent. The last code
   1.597 +     * must be all ones.
   1.598 +     */
   1.599 +    Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
   1.600 +            "inconsistent bit counts");
   1.601 +    Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
   1.602 +
   1.603 +    for (n = 0;  n <= max_code; n++) {
   1.604 +        int len = tree[n].Len;
   1.605 +        if (len == 0) continue;
   1.606 +        /* Now reverse the bits */
   1.607 +        tree[n].Code = bi_reverse(next_code[len]++, len);
   1.608 +
   1.609 +        Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
   1.610 +             n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
   1.611 +    }
   1.612 +}
   1.613 +
   1.614 +/* ===========================================================================
   1.615 + * Construct one Huffman tree and assigns the code bit strings and lengths.
   1.616 + * Update the total bit length for the current block.
   1.617 + * IN assertion: the field freq is set for all tree elements.
   1.618 + * OUT assertions: the fields len and code are set to the optimal bit length
   1.619 + *     and corresponding code. The length opt_len is updated; static_len is
   1.620 + *     also updated if stree is not null. The field max_code is set.
   1.621 + */
   1.622 +local void build_tree(s, desc)
   1.623 +    deflate_state *s;
   1.624 +    tree_desc *desc; /* the tree descriptor */
   1.625 +{
   1.626 +    ct_data *tree         = desc->dyn_tree;
   1.627 +    const ct_data *stree  = desc->stat_desc->static_tree;
   1.628 +    int elems             = desc->stat_desc->elems;
   1.629 +    int n, m;          /* iterate over heap elements */
   1.630 +    int max_code = -1; /* largest code with non zero frequency */
   1.631 +    int node;          /* new node being created */
   1.632 +
   1.633 +    /* Construct the initial heap, with least frequent element in
   1.634 +     * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
   1.635 +     * heap[0] is not used.
   1.636 +     */
   1.637 +    s->heap_len = 0, s->heap_max = HEAP_SIZE;
   1.638 +
   1.639 +    for (n = 0; n < elems; n++) {
   1.640 +        if (tree[n].Freq != 0) {
   1.641 +            s->heap[++(s->heap_len)] = max_code = n;
   1.642 +            s->depth[n] = 0;
   1.643 +        } else {
   1.644 +            tree[n].Len = 0;
   1.645 +        }
   1.646 +    }
   1.647 +
   1.648 +    /* The pkzip format requires that at least one distance code exists,
   1.649 +     * and that at least one bit should be sent even if there is only one
   1.650 +     * possible code. So to avoid special checks later on we force at least
   1.651 +     * two codes of non zero frequency.
   1.652 +     */
   1.653 +    while (s->heap_len < 2) {
   1.654 +        node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
   1.655 +        tree[node].Freq = 1;
   1.656 +        s->depth[node] = 0;
   1.657 +        s->opt_len--; if (stree) s->static_len -= stree[node].Len;
   1.658 +        /* node is 0 or 1 so it does not have extra bits */
   1.659 +    }
   1.660 +    desc->max_code = max_code;
   1.661 +
   1.662 +    /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
   1.663 +     * establish sub-heaps of increasing lengths:
   1.664 +     */
   1.665 +    for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
   1.666 +
   1.667 +    /* Construct the Huffman tree by repeatedly combining the least two
   1.668 +     * frequent nodes.
   1.669 +     */
   1.670 +    node = elems;              /* next internal node of the tree */
   1.671 +    do {
   1.672 +        pqremove(s, tree, n);  /* n = node of least frequency */
   1.673 +        m = s->heap[SMALLEST]; /* m = node of next least frequency */
   1.674 +
   1.675 +        s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
   1.676 +        s->heap[--(s->heap_max)] = m;
   1.677 +
   1.678 +        /* Create a new node father of n and m */
   1.679 +        tree[node].Freq = tree[n].Freq + tree[m].Freq;
   1.680 +        s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
   1.681 +                                s->depth[n] : s->depth[m]) + 1);
   1.682 +        tree[n].Dad = tree[m].Dad = (ush)node;
   1.683 +#ifdef DUMP_BL_TREE
   1.684 +        if (tree == s->bl_tree) {
   1.685 +            fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
   1.686 +                    node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
   1.687 +        }
   1.688 +#endif
   1.689 +        /* and insert the new node in the heap */
   1.690 +        s->heap[SMALLEST] = node++;
   1.691 +        pqdownheap(s, tree, SMALLEST);
   1.692 +
   1.693 +    } while (s->heap_len >= 2);
   1.694 +
   1.695 +    s->heap[--(s->heap_max)] = s->heap[SMALLEST];
   1.696 +
   1.697 +    /* At this point, the fields freq and dad are set. We can now
   1.698 +     * generate the bit lengths.
   1.699 +     */
   1.700 +    gen_bitlen(s, (tree_desc *)desc);
   1.701 +
   1.702 +    /* The field len is now set, we can generate the bit codes */
   1.703 +    gen_codes ((ct_data *)tree, max_code, s->bl_count);
   1.704 +}
   1.705 +
   1.706 +/* ===========================================================================
   1.707 + * Scan a literal or distance tree to determine the frequencies of the codes
   1.708 + * in the bit length tree.
   1.709 + */
   1.710 +local void scan_tree (s, tree, max_code)
   1.711 +    deflate_state *s;
   1.712 +    ct_data *tree;   /* the tree to be scanned */
   1.713 +    int max_code;    /* and its largest code of non zero frequency */
   1.714 +{
   1.715 +    int n;                     /* iterates over all tree elements */
   1.716 +    int prevlen = -1;          /* last emitted length */
   1.717 +    int curlen;                /* length of current code */
   1.718 +    int nextlen = tree[0].Len; /* length of next code */
   1.719 +    int count = 0;             /* repeat count of the current code */
   1.720 +    int max_count = 7;         /* max repeat count */
   1.721 +    int min_count = 4;         /* min repeat count */
   1.722 +
   1.723 +    if (nextlen == 0) max_count = 138, min_count = 3;
   1.724 +    tree[max_code+1].Len = (ush)0xffff; /* guard */
   1.725 +
   1.726 +    for (n = 0; n <= max_code; n++) {
   1.727 +        curlen = nextlen; nextlen = tree[n+1].Len;
   1.728 +        if (++count < max_count && curlen == nextlen) {
   1.729 +            continue;
   1.730 +        } else if (count < min_count) {
   1.731 +            s->bl_tree[curlen].Freq += count;
   1.732 +        } else if (curlen != 0) {
   1.733 +            if (curlen != prevlen) s->bl_tree[curlen].Freq++;
   1.734 +            s->bl_tree[REP_3_6].Freq++;
   1.735 +        } else if (count <= 10) {
   1.736 +            s->bl_tree[REPZ_3_10].Freq++;
   1.737 +        } else {
   1.738 +            s->bl_tree[REPZ_11_138].Freq++;
   1.739 +        }
   1.740 +        count = 0; prevlen = curlen;
   1.741 +        if (nextlen == 0) {
   1.742 +            max_count = 138, min_count = 3;
   1.743 +        } else if (curlen == nextlen) {
   1.744 +            max_count = 6, min_count = 3;
   1.745 +        } else {
   1.746 +            max_count = 7, min_count = 4;
   1.747 +        }
   1.748 +    }
   1.749 +}
   1.750 +
   1.751 +/* ===========================================================================
   1.752 + * Send a literal or distance tree in compressed form, using the codes in
   1.753 + * bl_tree.
   1.754 + */
   1.755 +local void send_tree (s, tree, max_code)
   1.756 +    deflate_state *s;
   1.757 +    ct_data *tree; /* the tree to be scanned */
   1.758 +    int max_code;       /* and its largest code of non zero frequency */
   1.759 +{
   1.760 +    int n;                     /* iterates over all tree elements */
   1.761 +    int prevlen = -1;          /* last emitted length */
   1.762 +    int curlen;                /* length of current code */
   1.763 +    int nextlen = tree[0].Len; /* length of next code */
   1.764 +    int count = 0;             /* repeat count of the current code */
   1.765 +    int max_count = 7;         /* max repeat count */
   1.766 +    int min_count = 4;         /* min repeat count */
   1.767 +
   1.768 +    /* tree[max_code+1].Len = -1; */  /* guard already set */
   1.769 +    if (nextlen == 0) max_count = 138, min_count = 3;
   1.770 +
   1.771 +    for (n = 0; n <= max_code; n++) {
   1.772 +        curlen = nextlen; nextlen = tree[n+1].Len;
   1.773 +        if (++count < max_count && curlen == nextlen) {
   1.774 +            continue;
   1.775 +        } else if (count < min_count) {
   1.776 +            do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
   1.777 +
   1.778 +        } else if (curlen != 0) {
   1.779 +            if (curlen != prevlen) {
   1.780 +                send_code(s, curlen, s->bl_tree); count--;
   1.781 +            }
   1.782 +            Assert(count >= 3 && count <= 6, " 3_6?");
   1.783 +            send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
   1.784 +
   1.785 +        } else if (count <= 10) {
   1.786 +            send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
   1.787 +
   1.788 +        } else {
   1.789 +            send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
   1.790 +        }
   1.791 +        count = 0; prevlen = curlen;
   1.792 +        if (nextlen == 0) {
   1.793 +            max_count = 138, min_count = 3;
   1.794 +        } else if (curlen == nextlen) {
   1.795 +            max_count = 6, min_count = 3;
   1.796 +        } else {
   1.797 +            max_count = 7, min_count = 4;
   1.798 +        }
   1.799 +    }
   1.800 +}
   1.801 +
   1.802 +/* ===========================================================================
   1.803 + * Construct the Huffman tree for the bit lengths and return the index in
   1.804 + * bl_order of the last bit length code to send.
   1.805 + */
   1.806 +local int build_bl_tree(s)
   1.807 +    deflate_state *s;
   1.808 +{
   1.809 +    int max_blindex;  /* index of last bit length code of non zero freq */
   1.810 +
   1.811 +    /* Determine the bit length frequencies for literal and distance trees */
   1.812 +    scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
   1.813 +    scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
   1.814 +
   1.815 +    /* Build the bit length tree: */
   1.816 +    build_tree(s, (tree_desc *)(&(s->bl_desc)));
   1.817 +    /* opt_len now includes the length of the tree representations, except
   1.818 +     * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
   1.819 +     */
   1.820 +
   1.821 +    /* Determine the number of bit length codes to send. The pkzip format
   1.822 +     * requires that at least 4 bit length codes be sent. (appnote.txt says
   1.823 +     * 3 but the actual value used is 4.)
   1.824 +     */
   1.825 +    for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
   1.826 +        if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
   1.827 +    }
   1.828 +    /* Update opt_len to include the bit length tree and counts */
   1.829 +    s->opt_len += 3*(max_blindex+1) + 5+5+4;
   1.830 +    Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
   1.831 +            s->opt_len, s->static_len));
   1.832 +
   1.833 +    return max_blindex;
   1.834 +}
   1.835 +
   1.836 +/* ===========================================================================
   1.837 + * Send the header for a block using dynamic Huffman trees: the counts, the
   1.838 + * lengths of the bit length codes, the literal tree and the distance tree.
   1.839 + * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
   1.840 + */
   1.841 +local void send_all_trees(s, lcodes, dcodes, blcodes)
   1.842 +    deflate_state *s;
   1.843 +    int lcodes, dcodes, blcodes; /* number of codes for each tree */
   1.844 +{
   1.845 +    int rank;                    /* index in bl_order */
   1.846 +
   1.847 +    Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
   1.848 +    Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
   1.849 +            "too many codes");
   1.850 +    Tracev((stderr, "\nbl counts: "));
   1.851 +    send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
   1.852 +    send_bits(s, dcodes-1,   5);
   1.853 +    send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
   1.854 +    for (rank = 0; rank < blcodes; rank++) {
   1.855 +        Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
   1.856 +        send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
   1.857 +    }
   1.858 +    Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
   1.859 +
   1.860 +    send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
   1.861 +    Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
   1.862 +
   1.863 +    send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
   1.864 +    Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
   1.865 +}
   1.866 +
   1.867 +/* ===========================================================================
   1.868 + * Send a stored block
   1.869 + */
   1.870 +void _tr_stored_block(s, buf, stored_len, eof)
   1.871 +    deflate_state *s;
   1.872 +    charf *buf;       /* input block */
   1.873 +    ulg stored_len;   /* length of input block */
   1.874 +    int eof;          /* true if this is the last block for a file */
   1.875 +{
   1.876 +    send_bits(s, (STORED_BLOCK<<1)+eof, 3);  /* send block type */
   1.877 +#ifdef DEBUG
   1.878 +    s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
   1.879 +    s->compressed_len += (stored_len + 4) << 3;
   1.880 +#endif
   1.881 +    copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
   1.882 +}
   1.883 +
   1.884 +/* ===========================================================================
   1.885 + * Send one empty static block to give enough lookahead for inflate.
   1.886 + * This takes 10 bits, of which 7 may remain in the bit buffer.
   1.887 + * The current inflate code requires 9 bits of lookahead. If the
   1.888 + * last two codes for the previous block (real code plus EOB) were coded
   1.889 + * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
   1.890 + * the last real code. In this case we send two empty static blocks instead
   1.891 + * of one. (There are no problems if the previous block is stored or fixed.)
   1.892 + * To simplify the code, we assume the worst case of last real code encoded
   1.893 + * on one bit only.
   1.894 + */
   1.895 +void _tr_align(s)
   1.896 +    deflate_state *s;
   1.897 +{
   1.898 +    send_bits(s, STATIC_TREES<<1, 3);
   1.899 +    send_code(s, END_BLOCK, static_ltree);
   1.900 +#ifdef DEBUG
   1.901 +    s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
   1.902 +#endif
   1.903 +    bi_flush(s);
   1.904 +    /* Of the 10 bits for the empty block, we have already sent
   1.905 +     * (10 - bi_valid) bits. The lookahead for the last real code (before
   1.906 +     * the EOB of the previous block) was thus at least one plus the length
   1.907 +     * of the EOB plus what we have just sent of the empty static block.
   1.908 +     */
   1.909 +    if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
   1.910 +        send_bits(s, STATIC_TREES<<1, 3);
   1.911 +        send_code(s, END_BLOCK, static_ltree);
   1.912 +#ifdef DEBUG
   1.913 +        s->compressed_len += 10L;
   1.914 +#endif
   1.915 +        bi_flush(s);
   1.916 +    }
   1.917 +    s->last_eob_len = 7;
   1.918 +}
   1.919 +
   1.920 +/* ===========================================================================
   1.921 + * Determine the best encoding for the current block: dynamic trees, static
   1.922 + * trees or store, and output the encoded block to the zip file.
   1.923 + */
   1.924 +void _tr_flush_block(s, buf, stored_len, eof)
   1.925 +    deflate_state *s;
   1.926 +    charf *buf;       /* input block, or NULL if too old */
   1.927 +    ulg stored_len;   /* length of input block */
   1.928 +    int eof;          /* true if this is the last block for a file */
   1.929 +{
   1.930 +    ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
   1.931 +    int max_blindex = 0;  /* index of last bit length code of non zero freq */
   1.932 +
   1.933 +    /* Build the Huffman trees unless a stored block is forced */
   1.934 +    if (s->level > 0) {
   1.935 +
   1.936 +        /* Check if the file is binary or text */
   1.937 +        if (stored_len > 0 && s->strm->data_type == Z_UNKNOWN)
   1.938 +            set_data_type(s);
   1.939 +
   1.940 +        /* Construct the literal and distance trees */
   1.941 +        build_tree(s, (tree_desc *)(&(s->l_desc)));
   1.942 +        Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
   1.943 +                s->static_len));
   1.944 +
   1.945 +        build_tree(s, (tree_desc *)(&(s->d_desc)));
   1.946 +        Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
   1.947 +                s->static_len));
   1.948 +        /* At this point, opt_len and static_len are the total bit lengths of
   1.949 +         * the compressed block data, excluding the tree representations.
   1.950 +         */
   1.951 +
   1.952 +        /* Build the bit length tree for the above two trees, and get the index
   1.953 +         * in bl_order of the last bit length code to send.
   1.954 +         */
   1.955 +        max_blindex = build_bl_tree(s);
   1.956 +
   1.957 +        /* Determine the best encoding. Compute the block lengths in bytes. */
   1.958 +        opt_lenb = (s->opt_len+3+7)>>3;
   1.959 +        static_lenb = (s->static_len+3+7)>>3;
   1.960 +
   1.961 +        Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
   1.962 +                opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
   1.963 +                s->last_lit));
   1.964 +
   1.965 +        if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
   1.966 +
   1.967 +    } else {
   1.968 +        Assert(buf != (char*)0, "lost buf");
   1.969 +        opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
   1.970 +    }
   1.971 +
   1.972 +#ifdef FORCE_STORED
   1.973 +    if (buf != (char*)0) { /* force stored block */
   1.974 +#else
   1.975 +    if (stored_len+4 <= opt_lenb && buf != (char*)0) {
   1.976 +                       /* 4: two words for the lengths */
   1.977 +#endif
   1.978 +        /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
   1.979 +         * Otherwise we can't have processed more than WSIZE input bytes since
   1.980 +         * the last block flush, because compression would have been
   1.981 +         * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
   1.982 +         * transform a block into a stored block.
   1.983 +         */
   1.984 +        _tr_stored_block(s, buf, stored_len, eof);
   1.985 +
   1.986 +#ifdef FORCE_STATIC
   1.987 +    } else if (static_lenb >= 0) { /* force static trees */
   1.988 +#else
   1.989 +    } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
   1.990 +#endif
   1.991 +        send_bits(s, (STATIC_TREES<<1)+eof, 3);
   1.992 +        compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
   1.993 +#ifdef DEBUG
   1.994 +        s->compressed_len += 3 + s->static_len;
   1.995 +#endif
   1.996 +    } else {
   1.997 +        send_bits(s, (DYN_TREES<<1)+eof, 3);
   1.998 +        send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
   1.999 +                       max_blindex+1);
  1.1000 +        compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
  1.1001 +#ifdef DEBUG
  1.1002 +        s->compressed_len += 3 + s->opt_len;
  1.1003 +#endif
  1.1004 +    }
  1.1005 +    Assert (s->compressed_len == s->bits_sent, "bad compressed size");
  1.1006 +    /* The above check is made mod 2^32, for files larger than 512 MB
  1.1007 +     * and uLong implemented on 32 bits.
  1.1008 +     */
  1.1009 +    init_block(s);
  1.1010 +
  1.1011 +    if (eof) {
  1.1012 +        bi_windup(s);
  1.1013 +#ifdef DEBUG
  1.1014 +        s->compressed_len += 7;  /* align on byte boundary */
  1.1015 +#endif
  1.1016 +    }
  1.1017 +    Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
  1.1018 +           s->compressed_len-7*eof));
  1.1019 +}
  1.1020 +
  1.1021 +/* ===========================================================================
  1.1022 + * Save the match info and tally the frequency counts. Return true if
  1.1023 + * the current block must be flushed.
  1.1024 + */
  1.1025 +int _tr_tally (s, dist, lc)
  1.1026 +    deflate_state *s;
  1.1027 +    unsigned dist;  /* distance of matched string */
  1.1028 +    unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
  1.1029 +{
  1.1030 +    s->d_buf[s->last_lit] = (ush)dist;
  1.1031 +    s->l_buf[s->last_lit++] = (uch)lc;
  1.1032 +    if (dist == 0) {
  1.1033 +        /* lc is the unmatched char */
  1.1034 +        s->dyn_ltree[lc].Freq++;
  1.1035 +    } else {
  1.1036 +        s->matches++;
  1.1037 +        /* Here, lc is the match length - MIN_MATCH */
  1.1038 +        dist--;             /* dist = match distance - 1 */
  1.1039 +        Assert((ush)dist < (ush)MAX_DIST(s) &&
  1.1040 +               (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
  1.1041 +               (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
  1.1042 +
  1.1043 +        s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
  1.1044 +        s->dyn_dtree[d_code(dist)].Freq++;
  1.1045 +    }
  1.1046 +
  1.1047 +#ifdef TRUNCATE_BLOCK
  1.1048 +    /* Try to guess if it is profitable to stop the current block here */
  1.1049 +    if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
  1.1050 +        /* Compute an upper bound for the compressed length */
  1.1051 +        ulg out_length = (ulg)s->last_lit*8L;
  1.1052 +        ulg in_length = (ulg)((long)s->strstart - s->block_start);
  1.1053 +        int dcode;
  1.1054 +        for (dcode = 0; dcode < D_CODES; dcode++) {
  1.1055 +            out_length += (ulg)s->dyn_dtree[dcode].Freq *
  1.1056 +                (5L+extra_dbits[dcode]);
  1.1057 +        }
  1.1058 +        out_length >>= 3;
  1.1059 +        Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
  1.1060 +               s->last_lit, in_length, out_length,
  1.1061 +               100L - out_length*100L/in_length));
  1.1062 +        if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
  1.1063 +    }
  1.1064 +#endif
  1.1065 +    return (s->last_lit == s->lit_bufsize-1);
  1.1066 +    /* We avoid equality with lit_bufsize because of wraparound at 64K
  1.1067 +     * on 16 bit machines and because stored blocks are restricted to
  1.1068 +     * 64K-1 bytes.
  1.1069 +     */
  1.1070 +}
  1.1071 +
  1.1072 +/* ===========================================================================
  1.1073 + * Send the block data compressed using the given Huffman trees
  1.1074 + */
  1.1075 +local void compress_block(s, ltree, dtree)
  1.1076 +    deflate_state *s;
  1.1077 +    ct_data *ltree; /* literal tree */
  1.1078 +    ct_data *dtree; /* distance tree */
  1.1079 +{
  1.1080 +    unsigned dist;      /* distance of matched string */
  1.1081 +    int lc;             /* match length or unmatched char (if dist == 0) */
  1.1082 +    unsigned lx = 0;    /* running index in l_buf */
  1.1083 +    unsigned code;      /* the code to send */
  1.1084 +    int extra;          /* number of extra bits to send */
  1.1085 +
  1.1086 +    if (s->last_lit != 0) do {
  1.1087 +        dist = s->d_buf[lx];
  1.1088 +        lc = s->l_buf[lx++];
  1.1089 +        if (dist == 0) {
  1.1090 +            send_code(s, lc, ltree); /* send a literal byte */
  1.1091 +            Tracecv(isgraph(lc), (stderr," '%c' ", lc));
  1.1092 +        } else {
  1.1093 +            /* Here, lc is the match length - MIN_MATCH */
  1.1094 +            code = _length_code[lc];
  1.1095 +            send_code(s, code+LITERALS+1, ltree); /* send the length code */
  1.1096 +            extra = extra_lbits[code];
  1.1097 +            if (extra != 0) {
  1.1098 +                lc -= base_length[code];
  1.1099 +                send_bits(s, lc, extra);       /* send the extra length bits */
  1.1100 +            }
  1.1101 +            dist--; /* dist is now the match distance - 1 */
  1.1102 +            code = d_code(dist);
  1.1103 +            Assert (code < D_CODES, "bad d_code");
  1.1104 +
  1.1105 +            send_code(s, code, dtree);       /* send the distance code */
  1.1106 +            extra = extra_dbits[code];
  1.1107 +            if (extra != 0) {
  1.1108 +                dist -= base_dist[code];
  1.1109 +                send_bits(s, dist, extra);   /* send the extra distance bits */
  1.1110 +            }
  1.1111 +        } /* literal or match pair ? */
  1.1112 +
  1.1113 +        /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
  1.1114 +        Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
  1.1115 +               "pendingBuf overflow");
  1.1116 +
  1.1117 +    } while (lx < s->last_lit);
  1.1118 +
  1.1119 +    send_code(s, END_BLOCK, ltree);
  1.1120 +    s->last_eob_len = ltree[END_BLOCK].Len;
  1.1121 +}
  1.1122 +
  1.1123 +/* ===========================================================================
  1.1124 + * Set the data type to BINARY or TEXT, using a crude approximation:
  1.1125 + * set it to Z_TEXT if all symbols are either printable characters (33 to 255)
  1.1126 + * or white spaces (9 to 13, or 32); or set it to Z_BINARY otherwise.
  1.1127 + * IN assertion: the fields Freq of dyn_ltree are set.
  1.1128 + */
  1.1129 +local void set_data_type(s)
  1.1130 +    deflate_state *s;
  1.1131 +{
  1.1132 +    int n;
  1.1133 +
  1.1134 +    for (n = 0; n < 9; n++)
  1.1135 +        if (s->dyn_ltree[n].Freq != 0)
  1.1136 +            break;
  1.1137 +    if (n == 9)
  1.1138 +        for (n = 14; n < 32; n++)
  1.1139 +            if (s->dyn_ltree[n].Freq != 0)
  1.1140 +                break;
  1.1141 +    s->strm->data_type = (n == 32) ? Z_TEXT : Z_BINARY;
  1.1142 +}
  1.1143 +
  1.1144 +/* ===========================================================================
  1.1145 + * Reverse the first len bits of a code, using straightforward code (a faster
  1.1146 + * method would use a table)
  1.1147 + * IN assertion: 1 <= len <= 15
  1.1148 + */
  1.1149 +local unsigned bi_reverse(code, len)
  1.1150 +    unsigned code; /* the value to invert */
  1.1151 +    int len;       /* its bit length */
  1.1152 +{
  1.1153 +    register unsigned res = 0;
  1.1154 +    do {
  1.1155 +        res |= code & 1;
  1.1156 +        code >>= 1, res <<= 1;
  1.1157 +    } while (--len > 0);
  1.1158 +    return res >> 1;
  1.1159 +}
  1.1160 +
  1.1161 +/* ===========================================================================
  1.1162 + * Flush the bit buffer, keeping at most 7 bits in it.
  1.1163 + */
  1.1164 +local void bi_flush(s)
  1.1165 +    deflate_state *s;
  1.1166 +{
  1.1167 +    if (s->bi_valid == 16) {
  1.1168 +        put_short(s, s->bi_buf);
  1.1169 +        s->bi_buf = 0;
  1.1170 +        s->bi_valid = 0;
  1.1171 +    } else if (s->bi_valid >= 8) {
  1.1172 +        put_byte(s, (Byte)s->bi_buf);
  1.1173 +        s->bi_buf >>= 8;
  1.1174 +        s->bi_valid -= 8;
  1.1175 +    }
  1.1176 +}
  1.1177 +
  1.1178 +/* ===========================================================================
  1.1179 + * Flush the bit buffer and align the output on a byte boundary
  1.1180 + */
  1.1181 +local void bi_windup(s)
  1.1182 +    deflate_state *s;
  1.1183 +{
  1.1184 +    if (s->bi_valid > 8) {
  1.1185 +        put_short(s, s->bi_buf);
  1.1186 +    } else if (s->bi_valid > 0) {
  1.1187 +        put_byte(s, (Byte)s->bi_buf);
  1.1188 +    }
  1.1189 +    s->bi_buf = 0;
  1.1190 +    s->bi_valid = 0;
  1.1191 +#ifdef DEBUG
  1.1192 +    s->bits_sent = (s->bits_sent+7) & ~7;
  1.1193 +#endif
  1.1194 +}
  1.1195 +
  1.1196 +/* ===========================================================================
  1.1197 + * Copy a stored block, storing first the length and its
  1.1198 + * one's complement if requested.
  1.1199 + */
  1.1200 +local void copy_block(s, buf, len, header)
  1.1201 +    deflate_state *s;
  1.1202 +    charf    *buf;    /* the input data */
  1.1203 +    unsigned len;     /* its length */
  1.1204 +    int      header;  /* true if block header must be written */
  1.1205 +{
  1.1206 +    bi_windup(s);        /* align on byte boundary */
  1.1207 +    s->last_eob_len = 8; /* enough lookahead for inflate */
  1.1208 +
  1.1209 +    if (header) {
  1.1210 +        put_short(s, (ush)len);
  1.1211 +        put_short(s, (ush)~len);
  1.1212 +#ifdef DEBUG
  1.1213 +        s->bits_sent += 2*16;
  1.1214 +#endif
  1.1215 +    }
  1.1216 +#ifdef DEBUG
  1.1217 +    s->bits_sent += (ulg)len<<3;
  1.1218 +#endif
  1.1219 +    while (len--) {
  1.1220 +        put_byte(s, *buf++);
  1.1221 +    }
  1.1222 +}