root/tools/packfi2/trees.c

DEFINITIONS

1. send_bits
2. tr_static_init
3. gen_trees_header
4. _tr_init
5. init_block
6. pqdownheap
7. gen_bitlen
8. gen_codes
9. build_tree
10. scan_tree
11. send_tree
12. build_bl_tree
13. send_all_trees
14. _tr_stored_block
15. _tr_align
16. _tr_flush_block
17. _tr_tally
18. compress_block
19. set_data_type
20. bi_reverse
21. bi_flush
22. bi_windup
23. copy_block

   1 /* trees.c -- output deflated data using Huffman coding

   2  * Copyright (C) 1995-2005 Jean-loup Gailly

   3  * For conditions of distribution and use, see copyright notice in zlib.h

   4  */
   6 /*

   7  *  ALGORITHM

   8  *

   9  *      The "deflation" process uses several Huffman trees. The more

  10  *      common source values are represented by shorter bit sequences.

  11  *

  12  *      Each code tree is stored in a compressed form which is itself

  13  * a Huffman encoding of the lengths of all the code strings (in

  14  * ascending order by source values).  The actual code strings are

  15  * reconstructed from the lengths in the inflate process, as described

  16  * in the deflate specification.

  17  *

  18  *  REFERENCES

  19  *

  20  *      Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".

  21  *      Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc

  22  *

  23  *      Storer, James A.

  24  *          Data Compression:  Methods and Theory, pp. 49-50.

  25  *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.

  26  *

  27  *      Sedgewick, R.

  28  *          Algorithms, p290.

  29  *          Addison-Wesley, 1983. ISBN 0-201-06672-6.

  30  */
  32 /* @(#) $Id$ */
  34 /* #define GEN_TREES_H */
  36 #include "deflate.h"
  38 #ifdef DEBUG
  39 #  include <ctype.h>
  40 #endif
  42 /* ===========================================================================

  43  * Constants

  44  */
  46 #define MAX_BL_BITS 7
  47 /* Bit length codes must not exceed MAX_BL_BITS bits */
  49 #define END_BLOCK 256
  50 /* end of block literal code */
  52 #define REP_3_6      16
  53 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
  55 #define REPZ_3_10    17
  56 /* repeat a zero length 3-10 times  (3 bits of repeat count) */
  58 #define REPZ_11_138  18
  59 /* repeat a zero length 11-138 times  (7 bits of repeat count) */
local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
  62    = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};
local const int extra_dbits[D_CODES] /* extra bits for each distance code */
  65    = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
  68    = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
local const uch bl_order[BL_CODES]
  71    = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
  72 /* The lengths of the bit length codes are sent in order of decreasing

  73  * probability, to avoid transmitting the lengths for unused bit length codes.

  74  */
  76 #define Buf_size (8 * 2*sizeof(char))
  77 /* Number of bits used within bi_buf. (bi_buf might be implemented on

  78  * more than 16 bits on some systems.)

  79  */
  81 /* ===========================================================================

  82  * Local data. These are initialized only once.

  83  */
  85 #define DIST_CODE_LEN  512 /* see definition of array dist_code below */
  87 #if defined(GEN_TREES_H) || !defined(STDC)
  88 /* non ANSI compilers may not accept trees.h */
local ct_data static_ltree[L_CODES+2];
  91 /* The static literal tree. Since the bit lengths are imposed, there is no

  92  * need for the L_CODES extra codes used during heap construction. However

  93  * The codes 286 and 287 are needed to build a canonical tree (see _tr_init

  94  * below).

  95  */
local ct_data static_dtree[D_CODES];
  98 /* The static distance tree. (Actually a trivial tree since all codes use

  99  * 5 bits.)

 100  */
uch _dist_code[DIST_CODE_LEN];
 103 /* Distance codes. The first 256 values correspond to the distances

 104  * 3 .. 258, the last 256 values correspond to the top 8 bits of

 105  * the 15 bit distances.

 106  */
uch _length_code[MAX_MATCH-MIN_MATCH+1];
 109 /* length code for each normalized match length (0 == MIN_MATCH) */
local int base_length[LENGTH_CODES];
 112 /* First normalized length for each code (0 = MIN_MATCH) */
local int base_dist[D_CODES];
 115 /* First normalized distance for each code (0 = distance of 1) */
 117 #else
 118 #  include "trees.h"
 119 #endif /* GEN_TREES_H */
 121 struct static_tree_desc_s {
 122     const ct_data *static_tree;  /* static tree or NULL */
 123     const intf *extra_bits;      /* extra bits for each code or NULL */
 124     int     extra_base;          /* base index for extra_bits */
 125     int     elems;               /* max number of elements in the tree */
 126     int     max_length;          /* max bit length for the codes */
 127 };
local static_tree_desc  static_l_desc =
 130 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
local static_tree_desc  static_d_desc =
 133 {static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};
local static_tree_desc  static_bl_desc =
 136 {(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
 138 /* ===========================================================================

 139  * Local (static) routines in this file.

 140  */
local void tr_static_init OF((void));
local void init_block     OF((deflate_state *s));
local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));
local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));
local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));
local void build_tree     OF((deflate_state *s, tree_desc *desc));
local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));
local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));
local int  build_bl_tree  OF((deflate_state *s));
local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
 152                               int blcodes));
local void compress_block OF((deflate_state *s, ct_data *ltree,
ct_data *dtree));
local void set_data_type  OF((deflate_state *s));
local unsigned bi_reverse OF((unsigned value, int length));
local void bi_windup      OF((deflate_state *s));
local void bi_flush       OF((deflate_state *s));
local void copy_block     OF((deflate_state *s, charf *buf, unsigned len,
 160                               int header));
 162 #ifdef GEN_TREES_H
local void gen_trees_header OF((void));
 164 #endif
 166 #ifndef DEBUG
 167 #  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
 168    /* Send a code of the given tree. c and tree must not have side effects */
 170 #else /* DEBUG */
 171 #  define send_code(s, c, tree) \
 172      { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
send_bits(s, tree[c].Code, tree[c].Len); }
 174 #endif
 176 /* ===========================================================================

 177  * Output a short LSB first on the stream.

 178  * IN assertion: there is enough room in pendingBuf.

 179  */
 180 #define put_short(s, w) { \
put_byte(s, (uch)((w) & 0xff)); \
put_byte(s, (uch)((ush)(w) >> 8)); \
 183 }
 185 /* ===========================================================================

 186  * Send a value on a given number of bits.

 187  * IN assertion: length <= 16 and value fits in length bits.

 188  */
 189 #ifdef DEBUG
local void send_bits      OF((deflate_state *s, int value, int length));
local void send_bits(s, value, length)
deflate_state *s;
 194     int value;  /* value to send */
 195     int length; /* number of bits */
 196 {
Tracevv((stderr," l %2d v %4x ", length, value));
Assert(length > 0 && length <= 15, "invalid length");
s->bits_sent += (ulg)length;
 201     /* If not enough room in bi_buf, use (valid) bits from bi_buf and

 202      * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))

 203      * unused bits in value.

 204      */
 205     if (s->bi_valid > (int)Buf_size - length) {
s->bi_buf |= (value << s->bi_valid);
put_short(s, s->bi_buf);
s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
s->bi_valid += length - Buf_size;
 210     } else {
s->bi_buf |= value << s->bi_valid;
s->bi_valid += length;
 213     }
 214 }
 215 #else /* !DEBUG */
 217 #define send_bits(s, value, length) \
 218 { int len = length;\
 219   if (s->bi_valid > (int)Buf_size - len) {\
 220     int val = value;\
s->bi_buf |= (val << s->bi_valid);\
put_short(s, s->bi_buf);\
s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
s->bi_valid += len - Buf_size;\
 225   } else {\
s->bi_buf |= (value) << s->bi_valid;\
s->bi_valid += len;\
 228   }\
 229 }
 230 #endif /* DEBUG */
 233 /* the arguments must not have side effects */
 235 /* ===========================================================================

 236  * Initialize the various 'constant' tables.

 237  */
local void tr_static_init()
 239 {
 240 #if defined(GEN_TREES_H) || !defined(STDC)
 241     static int static_init_done = 0;
 242     int n;        /* iterates over tree elements */
 243     int bits;     /* bit counter */
 244     int length;   /* length value */
 245     int code;     /* code value */
 246     int dist;     /* distance index */
ush bl_count[MAX_BITS+1];
 248     /* number of codes at each bit length for an optimal tree */
 250     if (static_init_done) return;
 252     /* For some embedded targets, global variables are not initialized: */
static_l_desc.static_tree = static_ltree;
static_l_desc.extra_bits = extra_lbits;
static_d_desc.static_tree = static_dtree;
static_d_desc.extra_bits = extra_dbits;
static_bl_desc.extra_bits = extra_blbits;
 259     /* Initialize the mapping length (0..255) -> length code (0..28) */
length = 0;
 261     for (code = 0; code < LENGTH_CODES-1; code++) {
base_length[code] = length;
 263         for (n = 0; n < (1<<extra_lbits[code]); n++) {
_length_code[length++] = (uch)code;
 265         }
 266     }
Assert (length == 256, "tr_static_init: length != 256");
 268     /* Note that the length 255 (match length 258) can be represented

 269      * in two different ways: code 284 + 5 bits or code 285, so we

 270      * overwrite length_code[255] to use the best encoding:

 271      */
_length_code[length-1] = (uch)code;
 274     /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
dist = 0;
 276     for (code = 0 ; code < 16; code++) {
base_dist[code] = dist;
 278         for (n = 0; n < (1<<extra_dbits[code]); n++) {
_dist_code[dist++] = (uch)code;
 280         }
 281     }
Assert (dist == 256, "tr_static_init: dist != 256");
dist >>= 7; /* from now on, all distances are divided by 128 */
 284     for ( ; code < D_CODES; code++) {
base_dist[code] = dist << 7;
 286         for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
_dist_code[256 + dist++] = (uch)code;
 288         }
 289     }
Assert (dist == 256, "tr_static_init: 256+dist != 512");
 292     /* Construct the codes of the static literal tree */
 293     for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
n = 0;
 295     while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
 296     while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
 297     while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
 298     while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
 299     /* Codes 286 and 287 do not exist, but we must include them in the

 300      * tree construction to get a canonical Huffman tree (longest code

 301      * all ones)

 302      */
gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
 305     /* The static distance tree is trivial: */
 306     for (n = 0; n < D_CODES; n++) {
static_dtree[n].Len = 5;
static_dtree[n].Code = bi_reverse((unsigned)n, 5);
 309     }
static_init_done = 1;
 312 #  ifdef GEN_TREES_H
gen_trees_header();
 314 #  endif
 315 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
 316 }
 318 /* ===========================================================================

 319  * Genererate the file trees.h describing the static trees.

 320  */
 321 #ifdef GEN_TREES_H
 322 #  ifndef DEBUG
 323 #    include <stdio.h>
 324 #  endif
 326 #  define SEPARATOR(i, last, width) \
 327       ((i) == (last)? "\n};\n\n" :    \
 328        ((i) % (width) == (width)-1 ? ",\n" : ", "))
 330 void gen_trees_header()
 331 {
FILE *header = fopen("trees.h", "w");
 333     int i;
Assert (header != NULL, "Can't open trees.h");
fprintf(header,
 337             "/* header created automatically with -DGEN_TREES_H */\n\n");
fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
 340     for (i = 0; i < L_CODES+2; i++) {
fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
 343     }
fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
 346     for (i = 0; i < D_CODES; i++) {
fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
 349     }
fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n");
 352     for (i = 0; i < DIST_CODE_LEN; i++) {
fprintf(header, "%2u%s", _dist_code[i],
SEPARATOR(i, DIST_CODE_LEN-1, 20));
 355     }
fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
 358     for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
fprintf(header, "%2u%s", _length_code[i],
SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
 361     }
fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
 364     for (i = 0; i < LENGTH_CODES; i++) {
fprintf(header, "%1u%s", base_length[i],
SEPARATOR(i, LENGTH_CODES-1, 20));
 367     }
fprintf(header, "local const int base_dist[D_CODES] = {\n");
 370     for (i = 0; i < D_CODES; i++) {
fprintf(header, "%5u%s", base_dist[i],
SEPARATOR(i, D_CODES-1, 10));
 373     }
fclose(header);
 376 }
 377 #endif /* GEN_TREES_H */
 379 /* ===========================================================================

 380  * Initialize the tree data structures for a new zlib stream.

 381  */
 382 void _tr_init(s)
deflate_state *s;
 384 {
tr_static_init();
s->l_desc.dyn_tree = s->dyn_ltree;
s->l_desc.stat_desc = &static_l_desc;
s->d_desc.dyn_tree = s->dyn_dtree;
s->d_desc.stat_desc = &static_d_desc;
s->bl_desc.dyn_tree = s->bl_tree;
s->bl_desc.stat_desc = &static_bl_desc;
s->bi_buf = 0;
s->bi_valid = 0;
s->last_eob_len = 8; /* enough lookahead for inflate */
 399 #ifdef DEBUG
s->compressed_len = 0L;
s->bits_sent = 0L;
 402 #endif
 404     /* Initialize the first block of the first file: */
init_block(s);
 406 }
 408 /* ===========================================================================

 409  * Initialize a new block.

 410  */
local void init_block(s)
deflate_state *s;
 413 {
 414     int n; /* iterates over tree elements */
 416     /* Initialize the trees. */
 417     for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
 418     for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
 419     for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
s->dyn_ltree[END_BLOCK].Freq = 1;
s->opt_len = s->static_len = 0L;
s->last_lit = s->matches = 0;
 424 }
 426 #define SMALLEST 1
 427 /* Index within the heap array of least frequent node in the Huffman tree */
 430 /* ===========================================================================

 431  * Remove the smallest element from the heap and recreate the heap with

 432  * one less element. Updates heap and heap_len.

 433  */
 434 #define pqremove(s, tree, top) \
 435 {\
top = s->heap[SMALLEST]; \
s->heap[SMALLEST] = s->heap[s->heap_len--]; \
pqdownheap(s, tree, SMALLEST); \
 439 }
 441 /* ===========================================================================

 442  * Compares to subtrees, using the tree depth as tie breaker when

 443  * the subtrees have equal frequency. This minimizes the worst case length.

 444  */
 445 #define smaller(tree, n, m, depth) \
 446    (tree[n].Freq < tree[m].Freq || \
 447    (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
 449 /* ===========================================================================

 450  * Restore the heap property by moving down the tree starting at node k,

 451  * exchanging a node with the smallest of its two sons if necessary, stopping

 452  * when the heap property is re-established (each father smaller than its

 453  * two sons).

 454  */
local void pqdownheap(s, tree, k)
deflate_state *s;
ct_data *tree;  /* the tree to restore */
 458     int k;               /* node to move down */
 459 {
 460     int v = s->heap[k];
 461     int j = k << 1;  /* left son of k */
 462     while (j <= s->heap_len) {
 463         /* Set j to the smallest of the two sons: */
 464         if (j < s->heap_len &&
smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
j++;
 467         }
 468         /* Exit if v is smaller than both sons */
 469         if (smaller(tree, v, s->heap[j], s->depth)) break;
 471         /* Exchange v with the smallest son */
s->heap[k] = s->heap[j];  k = j;
 474         /* And continue down the tree, setting j to the left son of k */
j <<= 1;
 476     }
s->heap[k] = v;
 478 }
 480 /* ===========================================================================

 481  * Compute the optimal bit lengths for a tree and update the total bit length

 482  * for the current block.

 483  * IN assertion: the fields freq and dad are set, heap[heap_max] and

 484  *    above are the tree nodes sorted by increasing frequency.

 485  * OUT assertions: the field len is set to the optimal bit length, the

 486  *     array bl_count contains the frequencies for each bit length.

 487  *     The length opt_len is updated; static_len is also updated if stree is

 488  *     not null.

 489  */
local void gen_bitlen(s, desc)
deflate_state *s;
tree_desc *desc;    /* the tree descriptor */
 493 {
ct_data *tree        = desc->dyn_tree;
 495     int max_code         = desc->max_code;
 496     const ct_data *stree = desc->stat_desc->static_tree;
 497     const intf *extra    = desc->stat_desc->extra_bits;
 498     int base             = desc->stat_desc->extra_base;
 499     int max_length       = desc->stat_desc->max_length;
 500     int h;              /* heap index */
 501     int n, m;           /* iterate over the tree elements */
 502     int bits;           /* bit length */
 503     int xbits;          /* extra bits */
ush f;              /* frequency */
 505     int overflow = 0;   /* number of elements with bit length too large */
 507     for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
 509     /* In a first pass, compute the optimal bit lengths (which may

 510      * overflow in the case of the bit length tree).

 511      */
tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
 514     for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
n = s->heap[h];
bits = tree[tree[n].Dad].Len + 1;
 517         if (bits > max_length) bits = max_length, overflow++;
tree[n].Len = (ush)bits;
 519         /* We overwrite tree[n].Dad which is no longer needed */
 521         if (n > max_code) continue; /* not a leaf node */
s->bl_count[bits]++;
xbits = 0;
 525         if (n >= base) xbits = extra[n-base];
f = tree[n].Freq;
s->opt_len += (ulg)f * (bits + xbits);
 528         if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
 529     }
 530     if (overflow == 0) return;
Trace((stderr,"\nbit length overflow\n"));
 533     /* This happens for example on obj2 and pic of the Calgary corpus */
 535     /* Find the first bit length which could increase: */
 536     do {
bits = max_length-1;
 538         while (s->bl_count[bits] == 0) bits--;
s->bl_count[bits]--;      /* move one leaf down the tree */
s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
s->bl_count[max_length]--;
 542         /* The brother of the overflow item also moves one step up,

 543          * but this does not affect bl_count[max_length]

 544          */
overflow -= 2;
 546     } while (overflow > 0);
 548     /* Now recompute all bit lengths, scanning in increasing frequency.

 549      * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all

 550      * lengths instead of fixing only the wrong ones. This idea is taken

 551      * from 'ar' written by Haruhiko Okumura.)

 552      */
 553     for (bits = max_length; bits != 0; bits--) {
n = s->bl_count[bits];
 555         while (n != 0) {
m = s->heap[--h];
 557             if (m > max_code) continue;
 558             if ((unsigned) tree[m].Len != (unsigned) bits) {
Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
s->opt_len += ((long)bits - (long)tree[m].Len)
 561                               *(long)tree[m].Freq;
tree[m].Len = (ush)bits;
 563             }
n--;
 565         }
 566     }
 567 }
 569 /* ===========================================================================

 570  * Generate the codes for a given tree and bit counts (which need not be

 571  * optimal).

 572  * IN assertion: the array bl_count contains the bit length statistics for

 573  * the given tree and the field len is set for all tree elements.

 574  * OUT assertion: the field code is set for all tree elements of non

 575  *     zero code length.

 576  */
local void gen_codes (tree, max_code, bl_count)
ct_data *tree;             /* the tree to decorate */
 579     int max_code;              /* largest code with non zero frequency */
ushf *bl_count;            /* number of codes at each bit length */
 581 {
ush next_code[MAX_BITS+1]; /* next code value for each bit length */
ush code = 0;              /* running code value */
 584     int bits;                  /* bit index */
 585     int n;                     /* code index */
 587     /* The distribution counts are first used to generate the code values

 588      * without bit reversal.

 589      */
 590     for (bits = 1; bits <= MAX_BITS; bits++) {
next_code[bits] = code = (code + bl_count[bits-1]) << 1;
 592     }
 593     /* Check that the bit counts in bl_count are consistent. The last code

 594      * must be all ones.

 595      */
Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
 597             "inconsistent bit counts");
Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
 600     for (n = 0;  n <= max_code; n++) {
 601         int len = tree[n].Len;
 602         if (len == 0) continue;
 603         /* Now reverse the bits */
tree[n].Code = bi_reverse(next_code[len]++, len);
Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
 608     }
 609 }
 611 /* ===========================================================================

 612  * Construct one Huffman tree and assigns the code bit strings and lengths.

 613  * Update the total bit length for the current block.

 614  * IN assertion: the field freq is set for all tree elements.

 615  * OUT assertions: the fields len and code are set to the optimal bit length

 616  *     and corresponding code. The length opt_len is updated; static_len is

 617  *     also updated if stree is not null. The field max_code is set.

 618  */
local void build_tree(s, desc)
deflate_state *s;
tree_desc *desc; /* the tree descriptor */
 622 {
ct_data *tree         = desc->dyn_tree;
 624     const ct_data *stree  = desc->stat_desc->static_tree;
 625     int elems             = desc->stat_desc->elems;
 626     int n, m;          /* iterate over heap elements */
 627     int max_code = -1; /* largest code with non zero frequency */
 628     int node;          /* new node being created */
 630     /* Construct the initial heap, with least frequent element in

 631      * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].

 632      * heap[0] is not used.

 633      */
s->heap_len = 0, s->heap_max = HEAP_SIZE;
 636     for (n = 0; n < elems; n++) {
 637         if (tree[n].Freq != 0) {
s->heap[++(s->heap_len)] = max_code = n;
s->depth[n] = 0;
 640         } else {
tree[n].Len = 0;
 642         }
 643     }
 645     /* The pkzip format requires that at least one distance code exists,

 646      * and that at least one bit should be sent even if there is only one

 647      * possible code. So to avoid special checks later on we force at least

 648      * two codes of non zero frequency.

 649      */
 650     while (s->heap_len < 2) {
node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
tree[node].Freq = 1;
s->depth[node] = 0;
s->opt_len--; if (stree) s->static_len -= stree[node].Len;
 655         /* node is 0 or 1 so it does not have extra bits */
 656     }
desc->max_code = max_code;
 659     /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,

 660      * establish sub-heaps of increasing lengths:

 661      */
 662     for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
 664     /* Construct the Huffman tree by repeatedly combining the least two

 665      * frequent nodes.

 666      */
node = elems;              /* next internal node of the tree */
 668     do {
pqremove(s, tree, n);  /* n = node of least frequency */
m = s->heap[SMALLEST]; /* m = node of next least frequency */
s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
s->heap[--(s->heap_max)] = m;
 675         /* Create a new node father of n and m */
tree[node].Freq = tree[n].Freq + tree[m].Freq;
s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
s->depth[n] : s->depth[m]) + 1);
tree[n].Dad = tree[m].Dad = (ush)node;
 680 #ifdef DUMP_BL_TREE
 681         if (tree == s->bl_tree) {
fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
 684         }
 685 #endif
 686         /* and insert the new node in the heap */
s->heap[SMALLEST] = node++;
pqdownheap(s, tree, SMALLEST);
 690     } while (s->heap_len >= 2);
s->heap[--(s->heap_max)] = s->heap[SMALLEST];
 694     /* At this point, the fields freq and dad are set. We can now

 695      * generate the bit lengths.

 696      */
gen_bitlen(s, (tree_desc *)desc);
 699     /* The field len is now set, we can generate the bit codes */
gen_codes ((ct_data *)tree, max_code, s->bl_count);
 701 }
 703 /* ===========================================================================

 704  * Scan a literal or distance tree to determine the frequencies of the codes

 705  * in the bit length tree.

 706  */
local void scan_tree (s, tree, max_code)
deflate_state *s;
ct_data *tree;   /* the tree to be scanned */
 710     int max_code;    /* and its largest code of non zero frequency */
 711 {
 712     int n;                     /* iterates over all tree elements */
 713     int prevlen = -1;          /* last emitted length */
 714     int curlen;                /* length of current code */
 715     int nextlen = tree[0].Len; /* length of next code */
 716     int count = 0;             /* repeat count of the current code */
 717     int max_count = 7;         /* max repeat count */
 718     int min_count = 4;         /* min repeat count */
 720     if (nextlen == 0) max_count = 138, min_count = 3;
tree[max_code+1].Len = (ush)0xffff; /* guard */
 723     for (n = 0; n <= max_code; n++) {
curlen = nextlen; nextlen = tree[n+1].Len;
 725         if (++count < max_count && curlen == nextlen) {
 726             continue;
 727         } else if (count < min_count) {
s->bl_tree[curlen].Freq += count;
 729         } else if (curlen != 0) {
 730             if (curlen != prevlen) s->bl_tree[curlen].Freq++;
s->bl_tree[REP_3_6].Freq++;
 732         } else if (count <= 10) {
s->bl_tree[REPZ_3_10].Freq++;
 734         } else {
s->bl_tree[REPZ_11_138].Freq++;
 736         }
count = 0; prevlen = curlen;
 738         if (nextlen == 0) {
max_count = 138, min_count = 3;
 740         } else if (curlen == nextlen) {
max_count = 6, min_count = 3;
 742         } else {
max_count = 7, min_count = 4;
 744         }
 745     }
 746 }
 748 /* ===========================================================================

 749  * Send a literal or distance tree in compressed form, using the codes in

 750  * bl_tree.

 751  */
local void send_tree (s, tree, max_code)
deflate_state *s;
ct_data *tree; /* the tree to be scanned */
 755     int max_code;       /* and its largest code of non zero frequency */
 756 {
 757     int n;                     /* iterates over all tree elements */
 758     int prevlen = -1;          /* last emitted length */
 759     int curlen;                /* length of current code */
 760     int nextlen = tree[0].Len; /* length of next code */
 761     int count = 0;             /* repeat count of the current code */
 762     int max_count = 7;         /* max repeat count */
 763     int min_count = 4;         /* min repeat count */
 765     /* tree[max_code+1].Len = -1; */  /* guard already set */
 766     if (nextlen == 0) max_count = 138, min_count = 3;
 768     for (n = 0; n <= max_code; n++) {
curlen = nextlen; nextlen = tree[n+1].Len;
 770         if (++count < max_count && curlen == nextlen) {
 771             continue;
 772         } else if (count < min_count) {
 773             do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
 775         } else if (curlen != 0) {
 776             if (curlen != prevlen) {
send_code(s, curlen, s->bl_tree); count--;
 778             }
Assert(count >= 3 && count <= 6, " 3_6?");
send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
 782         } else if (count <= 10) {
send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
 785         } else {
send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
 787         }
count = 0; prevlen = curlen;
 789         if (nextlen == 0) {
max_count = 138, min_count = 3;
 791         } else if (curlen == nextlen) {
max_count = 6, min_count = 3;
 793         } else {
max_count = 7, min_count = 4;
 795         }
 796     }
 797 }
 799 /* ===========================================================================

 800  * Construct the Huffman tree for the bit lengths and return the index in

 801  * bl_order of the last bit length code to send.

 802  */
local int build_bl_tree(s)
deflate_state *s;
 805 {
 806     int max_blindex;  /* index of last bit length code of non zero freq */
 808     /* Determine the bit length frequencies for literal and distance trees */
scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
 812     /* Build the bit length tree: */
build_tree(s, (tree_desc *)(&(s->bl_desc)));
 814     /* opt_len now includes the length of the tree representations, except

 815      * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.

 816      */
 818     /* Determine the number of bit length codes to send. The pkzip format

 819      * requires that at least 4 bit length codes be sent. (appnote.txt says

 820      * 3 but the actual value used is 4.)

 821      */
 822     for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
 823         if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
 824     }
 825     /* Update opt_len to include the bit length tree and counts */
s->opt_len += 3*(max_blindex+1) + 5+5+4;
Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
s->opt_len, s->static_len));
 830     return max_blindex;
 831 }
 833 /* ===========================================================================

 834  * Send the header for a block using dynamic Huffman trees: the counts, the

 835  * lengths of the bit length codes, the literal tree and the distance tree.

 836  * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.

 837  */
local void send_all_trees(s, lcodes, dcodes, blcodes)
deflate_state *s;
 840     int lcodes, dcodes, blcodes; /* number of codes for each tree */
 841 {
 842     int rank;                    /* index in bl_order */
Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
 846             "too many codes");
Tracev((stderr, "\nbl counts: "));
send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
send_bits(s, dcodes-1,   5);
send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
 851     for (rank = 0; rank < blcodes; rank++) {
Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
 854     }
Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
 862 }
 864 /* ===========================================================================

 865  * Send a stored block

 866  */
 867 void _tr_stored_block(s, buf, stored_len, eof)
deflate_state *s;
charf *buf;       /* input block */
ulg stored_len;   /* length of input block */
 871     int eof;          /* true if this is the last block for a file */
 872 {
send_bits(s, (STORED_BLOCK<<1)+eof, 3);  /* send block type */
 874 #ifdef DEBUG
s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
s->compressed_len += (stored_len + 4) << 3;
 877 #endif
copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
 879 }
 881 /* ===========================================================================

 882  * Send one empty static block to give enough lookahead for inflate.

 883  * This takes 10 bits, of which 7 may remain in the bit buffer.

 884  * The current inflate code requires 9 bits of lookahead. If the

 885  * last two codes for the previous block (real code plus EOB) were coded

 886  * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode

 887  * the last real code. In this case we send two empty static blocks instead

 888  * of one. (There are no problems if the previous block is stored or fixed.)

 889  * To simplify the code, we assume the worst case of last real code encoded

 890  * on one bit only.

 891  */
 892 void _tr_align(s)
deflate_state *s;
 894 {
send_bits(s, STATIC_TREES<<1, 3);
send_code(s, END_BLOCK, static_ltree);
 897 #ifdef DEBUG
s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
 899 #endif
bi_flush(s);
 901     /* Of the 10 bits for the empty block, we have already sent

 902      * (10 - bi_valid) bits. The lookahead for the last real code (before

 903      * the EOB of the previous block) was thus at least one plus the length

 904      * of the EOB plus what we have just sent of the empty static block.

 905      */
 906     if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
send_bits(s, STATIC_TREES<<1, 3);
send_code(s, END_BLOCK, static_ltree);
 909 #ifdef DEBUG
s->compressed_len += 10L;
 911 #endif
bi_flush(s);
 913     }
s->last_eob_len = 7;
 915 }
 917 /* ===========================================================================

 918  * Determine the best encoding for the current block: dynamic trees, static

 919  * trees or store, and output the encoded block to the zip file.

 920  */
 921 void _tr_flush_block(s, buf, stored_len, eof)
deflate_state *s;
charf *buf;       /* input block, or NULL if too old */
ulg stored_len;   /* length of input block */
 925     int eof;          /* true if this is the last block for a file */
 926 {
ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
 928     int max_blindex = 0;  /* index of last bit length code of non zero freq */
 930     /* Build the Huffman trees unless a stored block is forced */
 931     if (s->level > 0) {
 933         /* Check if the file is binary or text */
 934         if (stored_len > 0 && s->strm->data_type == Z_UNKNOWN)
set_data_type(s);
 937         /* Construct the literal and distance trees */
build_tree(s, (tree_desc *)(&(s->l_desc)));
Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
s->static_len));
build_tree(s, (tree_desc *)(&(s->d_desc)));
Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
s->static_len));
 945         /* At this point, opt_len and static_len are the total bit lengths of

 946          * the compressed block data, excluding the tree representations.

 947          */
 949         /* Build the bit length tree for the above two trees, and get the index

 950          * in bl_order of the last bit length code to send.

 951          */
max_blindex = build_bl_tree(s);
 954         /* Determine the best encoding. Compute the block lengths in bytes. */
opt_lenb = (s->opt_len+3+7)>>3;
static_lenb = (s->static_len+3+7)>>3;
Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
s->last_lit));
 962         if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
 964     } else {
Assert(buf != (char*)0, "lost buf");
opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
 967     }
 969 #ifdef FORCE_STORED
 970     if (buf != (char*)0) { /* force stored block */
 971 #else
 972     if (stored_len+4 <= opt_lenb && buf != (char*)0) {
 973                        /* 4: two words for the lengths */
 974 #endif
 975         /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.

 976          * Otherwise we can't have processed more than WSIZE input bytes since

 977          * the last block flush, because compression would have been

 978          * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to

 979          * transform a block into a stored block.

 980          */
_tr_stored_block(s, buf, stored_len, eof);
 983 #ifdef FORCE_STATIC
 984     } else if (static_lenb >= 0) { /* force static trees */
 985 #else
 986     } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
 987 #endif
send_bits(s, (STATIC_TREES<<1)+eof, 3);
compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
 990 #ifdef DEBUG
s->compressed_len += 3 + s->static_len;
 992 #endif
 993     } else {
send_bits(s, (DYN_TREES<<1)+eof, 3);
send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
max_blindex+1);
compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
 998 #ifdef DEBUG
s->compressed_len += 3 + s->opt_len;
1000 #endif
1001     }
Assert (s->compressed_len == s->bits_sent, "bad compressed size");
1003     /* The above check is made mod 2^32, for files larger than 512 MB

1004      * and uLong implemented on 32 bits.

1005      */
init_block(s);
1008     if (eof) {
bi_windup(s);
1010 #ifdef DEBUG
s->compressed_len += 7;  /* align on byte boundary */
1012 #endif
1013     }
Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
s->compressed_len-7*eof));
1016 }
1018 /* ===========================================================================

1019  * Save the match info and tally the frequency counts. Return true if

1020  * the current block must be flushed.

1021  */
1022 int _tr_tally (s, dist, lc)
deflate_state *s;
1024     unsigned dist;  /* distance of matched string */
1025     unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
1026 {
s->d_buf[s->last_lit] = (ush)dist;
s->l_buf[s->last_lit++] = (uch)lc;
1029     if (dist == 0) {
1030         /* lc is the unmatched char */
s->dyn_ltree[lc].Freq++;
1032     } else {
s->matches++;
1034         /* Here, lc is the match length - MIN_MATCH */
dist--;             /* dist = match distance - 1 */
Assert((ush)dist < (ush)MAX_DIST(s) &&
1037                (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
1038                (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
s->dyn_dtree[d_code(dist)].Freq++;
1042     }
1044 #ifdef TRUNCATE_BLOCK
1045     /* Try to guess if it is profitable to stop the current block here */
1046     if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
1047         /* Compute an upper bound for the compressed length */
ulg out_length = (ulg)s->last_lit*8L;
ulg in_length = (ulg)((long)s->strstart - s->block_start);
1050         int dcode;
1051         for (dcode = 0; dcode < D_CODES; dcode++) {
out_length += (ulg)s->dyn_dtree[dcode].Freq *
1053                 (5L+extra_dbits[dcode]);
1054         }
out_length >>= 3;
Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
s->last_lit, in_length, out_length,
1058                100L - out_length*100L/in_length));
1059         if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
1060     }
1061 #endif
1062     return (s->last_lit == s->lit_bufsize-1);
1063     /* We avoid equality with lit_bufsize because of wraparound at 64K

1064      * on 16 bit machines and because stored blocks are restricted to

1065      * 64K-1 bytes.

1066      */
1067 }
1069 /* ===========================================================================

1070  * Send the block data compressed using the given Huffman trees

1071  */
local void compress_block(s, ltree, dtree)
deflate_state *s;
ct_data *ltree; /* literal tree */
ct_data *dtree; /* distance tree */
1076 {
1077     unsigned dist;      /* distance of matched string */
1078     int lc;             /* match length or unmatched char (if dist == 0) */
1079     unsigned lx = 0;    /* running index in l_buf */
1080     unsigned code;      /* the code to send */
1081     int extra;          /* number of extra bits to send */
1083     if (s->last_lit != 0) do {
dist = s->d_buf[lx];
lc = s->l_buf[lx++];
1086         if (dist == 0) {
send_code(s, lc, ltree); /* send a literal byte */
Tracecv(isgraph(lc), (stderr," '%c' ", lc));
1089         } else {
1090             /* Here, lc is the match length - MIN_MATCH */
code = _length_code[lc];
send_code(s, code+LITERALS+1, ltree); /* send the length code */
extra = extra_lbits[code];
1094             if (extra != 0) {
lc -= base_length[code];
send_bits(s, lc, extra);       /* send the extra length bits */
1097             }
dist--; /* dist is now the match distance - 1 */
code = d_code(dist);
Assert (code < D_CODES, "bad d_code");
send_code(s, code, dtree);       /* send the distance code */
extra = extra_dbits[code];
1104             if (extra != 0) {
dist -= base_dist[code];
send_bits(s, dist, extra);   /* send the extra distance bits */
1107             }
1108         } /* literal or match pair ? */
1110         /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
1112                "pendingBuf overflow");
1114     } while (lx < s->last_lit);
send_code(s, END_BLOCK, ltree);
s->last_eob_len = ltree[END_BLOCK].Len;
1118 }
1120 /* ===========================================================================

1121  * Set the data type to BINARY or TEXT, using a crude approximation:

1122  * set it to Z_TEXT if all symbols are either printable characters (33 to 255)

1123  * or white spaces (9 to 13, or 32); or set it to Z_BINARY otherwise.

1124  * IN assertion: the fields Freq of dyn_ltree are set.

1125  */
local void set_data_type(s)
deflate_state *s;
1128 {
1129     int n;
1131     for (n = 0; n < 9; n++)
1132         if (s->dyn_ltree[n].Freq != 0)
1133             break;
1134     if (n == 9)
1135         for (n = 14; n < 32; n++)
1136             if (s->dyn_ltree[n].Freq != 0)
1137                 break;
s->strm->data_type = (n == 32) ? Z_TEXT : Z_BINARY;
1139 }
1141 /* ===========================================================================

1142  * Reverse the first len bits of a code, using straightforward code (a faster

1143  * method would use a table)

1144  * IN assertion: 1 <= len <= 15

1145  */
local unsigned bi_reverse(code, len)
1147     unsigned code; /* the value to invert */
1148     int len;       /* its bit length */
1149 {
1150     register unsigned res = 0;
1151     do {
res |= code & 1;
code >>= 1, res <<= 1;
1154     } while (--len > 0);
1155     return res >> 1;
1156 }
1158 /* ===========================================================================

1159  * Flush the bit buffer, keeping at most 7 bits in it.

1160  */
local void bi_flush(s)
deflate_state *s;
1163 {
1164     if (s->bi_valid == 16) {
put_short(s, s->bi_buf);
s->bi_buf = 0;
s->bi_valid = 0;
1168     } else if (s->bi_valid >= 8) {
put_byte(s, (Byte)s->bi_buf);
s->bi_buf >>= 8;
s->bi_valid -= 8;
1172     }
1173 }
1175 /* ===========================================================================

1176  * Flush the bit buffer and align the output on a byte boundary

1177  */
local void bi_windup(s)
deflate_state *s;
1180 {
1181     if (s->bi_valid > 8) {
put_short(s, s->bi_buf);
1183     } else if (s->bi_valid > 0) {
put_byte(s, (Byte)s->bi_buf);
1185     }
s->bi_buf = 0;
s->bi_valid = 0;
1188 #ifdef DEBUG
s->bits_sent = (s->bits_sent+7) & ~7;
1190 #endif
1191 }
1193 /* ===========================================================================

1194  * Copy a stored block, storing first the length and its

1195  * one's complement if requested.

1196  */
local void copy_block(s, buf, len, header)
deflate_state *s;
charf    *buf;    /* the input data */
1200     unsigned len;     /* its length */
1201     int      header;  /* true if block header must be written */
1202 {
bi_windup(s);        /* align on byte boundary */
s->last_eob_len = 8; /* enough lookahead for inflate */
1206     if (header) {
put_short(s, (ush)len);
put_short(s, (ush)~len);
1209 #ifdef DEBUG
s->bits_sent += 2*16;
1211 #endif
1212     }
1213 #ifdef DEBUG
s->bits_sent += (ulg)len<<3;
1215 #endif
1216     while (len--) {
put_byte(s, *buf++);
1218     }
1219 }