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

     2  * Copyright (C) 1995-1998 Jean-loup Gailly

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

     4  */

     5 

     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  */

    31 

    32 /* @(#) $Id$ */

    33 

    34 /* #define GEN_TREES_H */

    35 

    36 #include <e32std.h>

    37 

    38 #include "deflate.h"

    39 

    40 #ifdef DEBUG

    41 #  include <ctype.h>

    42 #endif

    43 

    44 /* ===========================================================================

    45  * Constants

    46  */

    47 

    48 #define MAX_BL_BITS 7

    49 /* Bit length codes must not exceed MAX_BL_BITS bits */

    50 

    51 #define END_BLOCK 256

    52 /* end of block literal code */

    53 

    54 #define REP_3_6      16

    55 /* repeat previous bit length 3-6 times (2 bits of repeat count) */

    56 

    57 #define REPZ_3_10    17

    58 /* repeat a zero length 3-10 times  (3 bits of repeat count) */

    59 

    60 #define REPZ_11_138  18

    61 /* repeat a zero length 11-138 times  (7 bits of repeat count) */

    62 

    63 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */

    64    = {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};

    65 

    66 local const int extra_dbits[D_CODES] /* extra bits for each distance code */

    67    = {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};

    68 

    69 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */

    70    = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};

    71 

    72 local const uch bl_order[BL_CODES]

    73    = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};

    74 /* The lengths of the bit length codes are sent in order of decreasing

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

    76  */

    77 

    78 #define Buf_size (8 * 2*sizeof(char))

    79 /* Number of bits used within bi_buf. (bi_buf might be implemented on

    80  * more than 16 bits on some systems.)

    81  */

    82 

    83 /* ===========================================================================

    84  * Local data. These are initialized only once.

    85  */

    86 

    87 #define DIST_CODE_LEN  512 /* see definition of array dist_code below */

    88 

    89 #if defined(GEN_TREES_H) || !defined(STDC)

    90 /* non ANSI compilers may not accept trees.h */

    91 

    92 local ct_data static_ltree[L_CODES+2];

    93 /* The static literal tree. Since the bit lengths are imposed, there is no

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

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

    96  * below).

    97  */

    98 

    99 local ct_data static_dtree[D_CODES];

   100 /* The static distance tree. (Actually a trivial tree since all codes use

   101  * 5 bits.)

   102  */

   103 

   104 uch _dist_code[DIST_CODE_LEN];

   105 /* Distance codes. The first 256 values correspond to the distances

   106  * 3 .. 258, the last 256 values correspond to the top 8 bits of

   107  * the 15 bit distances.

   108  */

   109 

   110 uch _length_code[MAX_MATCH-MIN_MATCH+1];

   111 /* length code for each normalized match length (0 == MIN_MATCH) */

   112 

   113 local int base_length[LENGTH_CODES];

   114 /* First normalized length for each code (0 = MIN_MATCH) */

   115 

   116 local int base_dist[D_CODES];

   117 /* First normalized distance for each code (0 = distance of 1) */

   118 

   119 #else

   120 #  include "trees.h"

   121 #endif /* GEN_TREES_H */

   122 

   123 struct static_tree_desc_s {

   124     const ct_data *static_tree;  /* static tree or NULL */

   125     const intf *extra_bits;      /* extra bits for each code or NULL */

   126     int     extra_base;          /* base index for extra_bits */

   127     int     elems;               /* max number of elements in the tree */

   128     int     max_length;          /* max bit length for the codes */

   129 };

   130 

   131 const local static_tree_desc  static_l_desc =

   132 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};

   133 

   134 const local static_tree_desc  static_d_desc =

   135 {static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};

   136 

   137 const local static_tree_desc  static_bl_desc =

   138 {(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};

   139 

   140 /* ===========================================================================

   141  * Local (static) routines in this file.

   142  */

   143 

   144 local void tr_static_init OF((void));

   145 local void init_block     OF((deflate_state *s));

   146 local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));

   147 local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));

   148 local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));

   149 local void build_tree     OF((deflate_state *s, tree_desc *desc));

   150 local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));

   151 local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));

   152 local int  build_bl_tree  OF((deflate_state *s));

   153 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,

   154                               int blcodes));

   155 local void compress_block OF((deflate_state *s, ct_data *ltree,

   156                               ct_data *dtree));

   157 local void set_data_type  OF((deflate_state *s));

   158 local unsigned bi_reverse OF((unsigned value, int length));

   159 local void bi_windup      OF((deflate_state *s));

   160 local void bi_flush       OF((deflate_state *s));

   161 local void copy_block     OF((deflate_state *s, charf *buf, unsigned len,

   162                               int header));

   163 

   164 #ifdef GEN_TREES_H

   165 local void gen_trees_header OF((void));

   166 #endif

   167 

   168 #ifndef DEBUG

   169 #  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)

   170    /* Send a code of the given tree. c and tree must not have side effects */

   171 

   172 #else /* DEBUG */

   173 #  define send_code(s, c, tree) \

   174      { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \

   175        send_bits(s, tree[c].Code, tree[c].Len); }

   176 #endif

   177 

   178 /* ===========================================================================

   179  * Output a short LSB first on the stream.

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

   181  */

   182 #define put_short(s, w) { \

   183     put_byte(s, (uch)((w) & 0xff)); \

   184     put_byte(s, (uch)((ush)(w) >> 8)); \

   185 }

   186 

   187 /* ===========================================================================

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

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

   190  */

   191 #ifdef DEBUG

   192 local void send_bits      OF((deflate_state *s, int value, int length));

   193 

   194 local void send_bits(

   195     deflate_state *s,

   196     int value,  /* value to send */

   197     int length) /* number of bits */

   198 {

   199     Tracevv((stderr," l %2d v %4x ", length, value));

   200     Assert(length > 0 && length <= 15, "invalid length");

   201     s->bits_sent += (ulg)length;

   202 

   203     /* If not enough room in bi_buf, use (valid) bits from bi_buf and

   204      * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))

   205      * unused bits in value.

   206      */

   207     if (s->bi_valid > (int)Buf_size - length) {

   208         s->bi_buf |= (value << s->bi_valid);

   209         put_short(s, s->bi_buf);

   210         s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);

   211         s->bi_valid += length - Buf_size;

   212     } else {

   213         s->bi_buf |= value << s->bi_valid;

   214         s->bi_valid += length;

   215     }

   216 }

   217 #else /* !DEBUG */

   218 

   219 #define send_bits(s, value, length) \

   220 { int len = length;\

   221   if (s->bi_valid > (int)Buf_size - len) {\

   222     int val = value;\

   223     s->bi_buf |= (val << s->bi_valid);\

   224     put_short(s, s->bi_buf);\

   225     s->bi_buf = STATIC_CAST(ush,val >> (Buf_size - s->bi_valid));\

   226     s->bi_valid += len - Buf_size;\

   227   } else {\

   228     s->bi_buf |= (value) << s->bi_valid;\

   229     s->bi_valid += len;\

   230   }\

   231 }

   232 #endif /* DEBUG */

   233 

   234 

   235 #define MAX(a,b) (a >= b ? a : b)

   236 /* the arguments must not have side effects */

   237 

   238 /* ===========================================================================

   239  * Initialize the various 'constant' tables.

   240  */

   241 local void tr_static_init()

   242 {

   243 #if defined(GEN_TREES_H) || !defined(STDC)

   244     static int static_init_done = 0;

   245     int n;        /* iterates over tree elements */

   246     int bits;     /* bit counter */

   247     int length;   /* length value */

   248     int code;     /* code value */

   249     int dist;     /* distance index */

   250     ush bl_count[MAX_BITS+1];

   251     /* number of codes at each bit length for an optimal tree */

   252 

   253     if (static_init_done) return;

   254 

   255     /* For some embedded targets, global variables are not initialized: */

   256     static_l_desc.static_tree = static_ltree;

   257     static_l_desc.extra_bits = extra_lbits;

   258     static_d_desc.static_tree = static_dtree;

   259     static_d_desc.extra_bits = extra_dbits;

   260     static_bl_desc.extra_bits = extra_blbits;

   261 

   262     /* Initialize the mapping length (0..255) -> length code (0..28) */

   263     length = 0;

   264     for (code = 0; code < LENGTH_CODES-1; code++) {

   265         base_length[code] = length;

   266         for (n = 0; n < (1<<extra_lbits[code]); n++) {

   267             _length_code[length++] = (uch)code;

   268         }

   269     }

   270     Assert (length == 256, "tr_static_init: length != 256");

   271     /* Note that the length 255 (match length 258) can be represented

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

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

   274      */

   275     _length_code[length-1] = (uch)code;

   276 

   277     /* Initialize the mapping dist (0..32K) -> dist code (0..29) */

   278     dist = 0;

   279     for (code = 0 ; code < 16; code++) {

   280         base_dist[code] = dist;

   281         for (n = 0; n < (1<<extra_dbits[code]); n++) {

   282             _dist_code[dist++] = (uch)code;

   283         }

   284     }

   285     Assert (dist == 256, "tr_static_init: dist != 256");

   286     dist >>= 7; /* from now on, all distances are divided by 128 */

   287     for ( ; code < D_CODES; code++) {

   288         base_dist[code] = dist << 7;

   289         for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {

   290             _dist_code[256 + dist++] = (uch)code;

   291         }

   292     }

   293     Assert (dist == 256, "tr_static_init: 256+dist != 512");

   294 

   295     /* Construct the codes of the static literal tree */

   296     for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;

   297     n = 0;

   298     while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;

   299     while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;

   300     while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;

   301     while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;

   302     /* Codes 286 and 287 do not exist, but we must include them in the

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

   304      * all ones)

   305      */

   306     gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);

   307 

   308     /* The static distance tree is trivial: */

   309     for (n = 0; n < D_CODES; n++) {

   310         static_dtree[n].Len = 5;

   311         static_dtree[n].Code = bi_reverse((unsigned)n, 5);

   312     }

   313     static_init_done = 1;

   314 

   315 #  ifdef GEN_TREES_H

   316     gen_trees_header();

   317 #  endif

   318 #endif /* defined(GEN_TREES_H) || !defined(STDC) */

   319 }

   320 

   321 /* ===========================================================================

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

   323  */

   324 #ifdef GEN_TREES_H

   325 #  ifndef DEBUG

   326 #    include <stdio.h>

   327 #  endif

   328 

   329 #  define SEPARATOR(i, last, width) \

   330       ((i) == (last)? "\n};\n\n" :    \

   331        ((i) % (width) == (width)-1 ? ",\n" : ", "))

   332 

   333 void gen_trees_header()

   334 {

   335     FILE *header = fopen("trees.h", "w");

   336     int i;

   337 

   338     Assert (header != NULL, "Can't open trees.h");

   339     fprintf(header,

   340 	    "/* header created automatically with -DGEN_TREES_H */\n\n");

   341 

   342     fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");

   343     for (i = 0; i < L_CODES+2; i++) {

   344 	fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,

   345 		static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));

   346     }

   347 

   348     fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");

   349     for (i = 0; i < D_CODES; i++) {

   350 	fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,

   351 		static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));

   352     }

   353 

   354     fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n");

   355     for (i = 0; i < DIST_CODE_LEN; i++) {

   356 	fprintf(header, "%2u%s", _dist_code[i],

   357 		SEPARATOR(i, DIST_CODE_LEN-1, 20));

   358     }

   359 

   360     fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");

   361     for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {

   362 	fprintf(header, "%2u%s", _length_code[i],

   363 		SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));

   364     }

   365 

   366     fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");

   367     for (i = 0; i < LENGTH_CODES; i++) {

   368 	fprintf(header, "%1u%s", base_length[i],

   369 		SEPARATOR(i, LENGTH_CODES-1, 20));

   370     }

   371 

   372     fprintf(header, "local const int base_dist[D_CODES] = {\n");

   373     for (i = 0; i < D_CODES; i++) {

   374 	fprintf(header, "%5u%s", base_dist[i],

   375 		SEPARATOR(i, D_CODES-1, 10));

   376     }

   377 

   378     fclose(header);

   379 }

   380 #endif /* GEN_TREES_H */

   381 

   382 /* ===========================================================================

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

   384  */

   385 void _tr_init(

   386     deflate_state *s)

   387 {

   388     tr_static_init();

   389 

   390     s->l_desc.dyn_tree = s->dyn_ltree;

   391     s->l_desc.stat_desc = &static_l_desc;

   392 

   393     s->d_desc.dyn_tree = s->dyn_dtree;

   394     s->d_desc.stat_desc = &static_d_desc;

   395 

   396     s->bl_desc.dyn_tree = s->bl_tree;

   397     s->bl_desc.stat_desc = &static_bl_desc;

   398 

   399     s->bi_buf = 0;

   400     s->bi_valid = 0;

   401     s->last_eob_len = 8; /* enough lookahead for inflate */

   402 #ifdef DEBUG

   403     s->compressed_len = 0L;

   404     s->bits_sent = 0L;

   405 #endif

   406 

   407     /* Initialize the first block of the first file: */

   408     init_block(s);

   409 }

   410 

   411 /* ===========================================================================

   412  * Initialize a new block.

   413  */

   414 local void init_block(

   415     deflate_state *s)

   416 {

   417     int n; /* iterates over tree elements */

   418 

   419     /* Initialize the trees. */

   420     for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;

   421     for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;

   422     for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;

   423 

   424     s->dyn_ltree[END_BLOCK].Freq = 1;

   425     s->opt_len = s->static_len = 0L;

   426     s->last_lit = s->matches = 0;

   427 }

   428 

   429 #define SMALLEST 1

   430 /* Index within the heap array of least frequent node in the Huffman tree */

   431 

   432 

   433 /* ===========================================================================

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

   435  * one less element. Updates heap and heap_len.

   436  */

   437 #define pqremove(s, tree, top) \

   438 {\

   439     top = s->heap[SMALLEST]; \

   440     s->heap[SMALLEST] = s->heap[s->heap_len--]; \

   441     pqdownheap(s, tree, SMALLEST); \

   442 }

   443 

   444 /* ===========================================================================

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

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

   447  */

   448 #define smaller(tree, n, m, depth) \

   449    (tree[n].Freq < tree[m].Freq || \

   450    (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))

   451 

   452 /* ===========================================================================

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

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

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

   456  * two sons).

   457  */

   458 local void pqdownheap(

   459     deflate_state *s,

   460     ct_data *tree,  /* the tree to restore */

   461     int k)               /* node to move down */

   462 {

   463     int v = s->heap[k];

   464     int j = k << 1;  /* left son of k */

   465     while (j <= s->heap_len) {

   466         /* Set j to the smallest of the two sons: */

   467         if (j < s->heap_len &&

   468             smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {

   469             j++;

   470         }

   471         /* Exit if v is smaller than both sons */

   472         if (smaller(tree, v, s->heap[j], s->depth)) break;

   473 

   474         /* Exchange v with the smallest son */

   475         s->heap[k] = s->heap[j];  k = j;

   476 

   477         /* And continue down the tree, setting j to the left son of k */

   478         j <<= 1;

   479     }

   480     s->heap[k] = v;

   481 }

   482 

   483 /* ===========================================================================

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

   485  * for the current block.

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

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

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

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

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

   491  *     not null.

   492  */

   493 local void gen_bitlen(

   494     deflate_state *s,

   495     tree_desc *desc)   /* the tree descriptor */

   496 {

   497     ct_data *tree        = desc->dyn_tree;

   498     int max_code         = desc->max_code;

   499     const ct_data *stree = desc->stat_desc->static_tree;

   500     const intf *extra    = desc->stat_desc->extra_bits;

   501     int base             = desc->stat_desc->extra_base;

   502     int max_length       = desc->stat_desc->max_length;

   503     int h;              /* heap index */

   504     int n, m;           /* iterate over the tree elements */

   505     int bits;           /* bit length */

   506     int xbits;          /* extra bits */

   507     ush f;              /* frequency */

   508     int overflow = 0;   /* number of elements with bit length too large */

   509 

   510     for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;

   511 

   512     /* In a first pass, compute the optimal bit lengths (which may

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

   514      */

   515     tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */

   516 

   517     for (h = s->heap_max+1; h < HEAP_SIZE; h++) {

   518         n = s->heap[h];

   519         bits = tree[tree[n].Dad].Len + 1;

   520         if (bits > max_length) bits = max_length, overflow++;

   521         tree[n].Len = (ush)bits;

   522         /* We overwrite tree[n].Dad which is no longer needed */

   523 

   524         if (n > max_code) continue; /* not a leaf node */

   525 

   526         s->bl_count[bits]++;

   527         xbits = 0;

   528         if (n >= base) xbits = extra[n-base];

   529         f = tree[n].Freq;

   530         s->opt_len += (ulg)f * (bits + xbits);

   531         if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);

   532     }

   533     if (overflow == 0) return;

   534 

   535     Trace((stderr,"\nbit length overflow\n"));

   536     /* This happens for example on obj2 and pic of the Calgary corpus */

   537 

   538     /* Find the first bit length which could increase: */

   539     do {

   540         bits = max_length-1;

   541         while (s->bl_count[bits] == 0) bits--;

   542         s->bl_count[bits]--;      /* move one leaf down the tree */

   543         s->bl_count[bits+1] += 2; /* move one overflow item as its brother */

   544         s->bl_count[max_length]--;

   545         /* The brother of the overflow item also moves one step up,

   546          * but this does not affect bl_count[max_length]

   547          */

   548         overflow -= 2;

   549     } while (overflow > 0);

   550 

   551     /* Now recompute all bit lengths, scanning in increasing frequency.

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

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

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

   555      */

   556     for (bits = max_length; bits != 0; bits--) {

   557         n = s->bl_count[bits];

   558         while (n != 0) {

   559             m = s->heap[--h];

   560             if (m > max_code) continue;

   561             if (tree[m].Len != (unsigned) bits) {

   562                 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));

   563                 s->opt_len += ((long)bits - (long)tree[m].Len)

   564                               *(long)tree[m].Freq;

   565                 tree[m].Len = (ush)bits;

   566             }

   567             n--;

   568         }

   569     }

   570 }

   571 

   572 /* ===========================================================================

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

   574  * optimal).

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

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

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

   578  *     zero code length.

   579  */

   580 local void gen_codes (

   581     ct_data *tree,             /* the tree to decorate */

   582     int max_code,             /* largest code with non zero frequency */

   583     ushf *bl_count)            /* number of codes at each bit length */

   584 {

   585     ush next_code[MAX_BITS+1]; /* next code value for each bit length */

   586     ush code = 0;              /* running code value */

   587     int bits;                  /* bit index */

   588     int n;                     /* code index */

   589 

   590     /* The distribution counts are first used to generate the code values

   591      * without bit reversal.

   592      */

   593     for (bits = 1; bits <= MAX_BITS; bits++) {

   594         next_code[bits] = code = STATIC_CAST(ush,(code + bl_count[bits-1]) << 1);

   595     }

   596     /* Check that the bit counts in bl_count are consistent. The last code

   597      * must be all ones.

   598      */

   599     Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,

   600             "inconsistent bit counts");

   601     Tracev((stderr,"\ngen_codes: max_code %d ", max_code));

   602 

   603     for (n = 0;  n <= max_code; n++) {

   604         int len = tree[n].Len;

   605         if (len == 0) continue;

   606         /* Now reverse the bits */

   607         tree[n].Code = STATIC_CAST(ush,bi_reverse(next_code[len]++, len));

   608 

   609         Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",

   610              n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));

   611     }

   612 }

   613 

   614 /* ===========================================================================

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

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

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

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

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

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

   621  */

   622 local void build_tree(

   623     deflate_state *s,

   624     tree_desc *desc) /* the tree descriptor */

   625 {

   626     ct_data *tree         = desc->dyn_tree;

   627     const ct_data *stree  = desc->stat_desc->static_tree;

   628     int elems             = desc->stat_desc->elems;

   629     int n, m;          /* iterate over heap elements */

   630     int max_code = -1; /* largest code with non zero frequency */

   631     int node;          /* new node being created */

   632 

   633     /* Construct the initial heap, with least frequent element in

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

   635      * heap[0] is not used.

   636      */

   637     s->heap_len = 0, s->heap_max = HEAP_SIZE;

   638 

   639     for (n = 0; n < elems; n++) {

   640         if (tree[n].Freq != 0) {

   641             s->heap[++(s->heap_len)] = max_code = n;

   642             s->depth[n] = 0;

   643         } else {

   644             tree[n].Len = 0;

   645         }

   646     }

   647 

   648     /* The pkzip format requires that at least one distance code exists,

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

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

   651      * two codes of non zero frequency.

   652      */

   653     while (s->heap_len < 2) {

   654         node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);

   655         tree[node].Freq = 1;

   656         s->depth[node] = 0;

   657         s->opt_len--; if (stree) s->static_len -= stree[node].Len;

   658         /* node is 0 or 1 so it does not have extra bits */

   659     }

   660     desc->max_code = max_code;

   661 

   662     /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,

   663      * establish sub-heaps of increasing lengths:

   664      */

   665     for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);

   666 

   667     /* Construct the Huffman tree by repeatedly combining the least two

   668      * frequent nodes.

   669      */

   670     node = elems;              /* next internal node of the tree */

   671     do {

   672         pqremove(s, tree, n);  /* n = node of least frequency */

   673         m = s->heap[SMALLEST]; /* m = node of next least frequency */

   674 

   675         s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */

   676         s->heap[--(s->heap_max)] = m;

   677 

   678         /* Create a new node father of n and m */

   679         tree[node].Freq = STATIC_CAST(ush,tree[n].Freq + tree[m].Freq);

   680         s->depth[node] = (uch) (MAX(s->depth[n], s->depth[m]) + 1);

   681         tree[n].Dad = tree[m].Dad = (ush)node;

   682 #ifdef DUMP_BL_TREE

   683         if (tree == s->bl_tree) {

   684             fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",

   685                     node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);

   686         }

   687 #endif

   688         /* and insert the new node in the heap */

   689         s->heap[SMALLEST] = node++;

   690         pqdownheap(s, tree, SMALLEST);

   691 

   692     } while (s->heap_len >= 2);

   693 

   694     s->heap[--(s->heap_max)] = s->heap[SMALLEST];

   695 

   696     /* At this point, the fields freq and dad are set. We can now

   697      * generate the bit lengths.

   698      */

   699     gen_bitlen(s, (tree_desc *)desc);

   700 

   701     /* The field len is now set, we can generate the bit codes */

   702     gen_codes ((ct_data *)tree, max_code, s->bl_count);

   703 }

   704 

   705 /* ===========================================================================

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

   707  * in the bit length tree.

   708  */

   709 local void scan_tree (

   710     deflate_state *s,

   711     ct_data *tree,   /* the tree to be scanned */

   712     int max_code)    /* and its largest code of non zero frequency */

   713 {

   714     int n;                     /* iterates over all tree elements */

   715     int prevlen = -1;          /* last emitted length */

   716     int curlen;                /* length of current code */

   717     int nextlen = tree[0].Len; /* length of next code */

   718     int count = 0;             /* repeat count of the current code */

   719     int max_count = 7;         /* max repeat count */

   720     int min_count = 4;         /* min repeat count */

   721 

   722     if (nextlen == 0) max_count = 138, min_count = 3;

   723     tree[max_code+1].Len = (ush)0xffff; /* guard */

   724 

   725     for (n = 0; n <= max_code; n++) {

   726         curlen = nextlen; nextlen = tree[n+1].Len;

   727         if (++count < max_count && curlen == nextlen) {

   728             continue;

   729         } else if (count < min_count) {

   730 			s->bl_tree[curlen].Freq = STATIC_CAST(ush, s->bl_tree[curlen].Freq + count);

   731         } else if (curlen != 0) {

   732             if (curlen != prevlen) s->bl_tree[curlen].Freq++;

   733             s->bl_tree[REP_3_6].Freq++;

   734         } else if (count <= 10) {

   735             s->bl_tree[REPZ_3_10].Freq++;

   736         } else {

   737             s->bl_tree[REPZ_11_138].Freq++;

   738         }

   739         count = 0; prevlen = curlen;

   740         if (nextlen == 0) {

   741             max_count = 138, min_count = 3;

   742         } else if (curlen == nextlen) {

   743             max_count = 6, min_count = 3;

   744         } else {

   745             max_count = 7, min_count = 4;

   746         }

   747     }

   748 }

   749 

   750 /* ===========================================================================

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

   752  * bl_tree.

   753  */

   754 local void send_tree (

   755     deflate_state *s,

   756     ct_data *tree, /* the tree to be scanned */

   757     int max_code)       /* and its largest code of non zero frequency */

   758 {

   759     int n;                     /* iterates over all tree elements */

   760     int prevlen = -1;          /* last emitted length */

   761     int curlen;                /* length of current code */

   762     int nextlen = tree[0].Len; /* length of next code */

   763     int count = 0;             /* repeat count of the current code */

   764     int max_count = 7;         /* max repeat count */

   765     int min_count = 4;         /* min repeat count */

   766 

   767     /* tree[max_code+1].Len = -1; */  /* guard already set */

   768     if (nextlen == 0) max_count = 138, min_count = 3;

   769 

   770     for (n = 0; n <= max_code; n++) {

   771         curlen = nextlen; nextlen = tree[n+1].Len;

   772         if (++count < max_count && curlen == nextlen) {

   773             continue;

   774         } else if (count < min_count) {

   775             do { send_code(s, curlen, s->bl_tree); } while (--count != 0);

   776 

   777         } else if (curlen != 0) {

   778             if (curlen != prevlen) {

   779                 send_code(s, curlen, s->bl_tree); count--;

   780             }

   781             Assert(count >= 3 && count <= 6, " 3_6?");

   782             send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);

   783 

   784         } else if (count <= 10) {

   785             send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);

   786 

   787         } else {

   788             send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);

   789         }

   790         count = 0; prevlen = curlen;

   791         if (nextlen == 0) {

   792             max_count = 138, min_count = 3;

   793         } else if (curlen == nextlen) {

   794             max_count = 6, min_count = 3;

   795         } else {

   796             max_count = 7, min_count = 4;

   797         }

   798     }

   799 }

   800 

   801 /* ===========================================================================

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

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

   804  */

   805 local int build_bl_tree(

   806     deflate_state *s)

   807 {

   808     int max_blindex;  /* index of last bit length code of non zero freq */

   809 

   810     /* Determine the bit length frequencies for literal and distance trees */

   811     scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);

   812     scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);

   813 

   814     /* Build the bit length tree: */

   815     build_tree(s, (tree_desc *)(&(s->bl_desc)));

   816     /* opt_len now includes the length of the tree representations, except

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

   818      */

   819 

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

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

   822      * 3 but the actual value used is 4.)

   823      */

   824     for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {

   825         if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;

   826     }

   827     /* Update opt_len to include the bit length tree and counts */

   828     s->opt_len += 3*(max_blindex+1) + 5+5+4;

   829     Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",

   830             s->opt_len, s->static_len));

   831 

   832     return max_blindex;

   833 }

   834 

   835 /* ===========================================================================

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

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

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

   839  */

   840 local void send_all_trees(

   841     deflate_state *s,

   842     int lcodes, int dcodes, int blcodes) /* number of codes for each tree */

   843 {

   844     int rank;                    /* index in bl_order */

   845 

   846     Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");

   847     Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,

   848             "too many codes");

   849     Tracev((stderr, "\nbl counts: "));

   850     send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */

   851     send_bits(s, dcodes-1,   5);

   852     send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */

   853     for (rank = 0; rank < blcodes; rank++) {

   854         Tracev((stderr, "\nbl code %2d ", bl_order[rank]));

   855         send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);

   856     }

   857     Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));

   858 

   859     send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */

   860     Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));

   861 

   862     send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */

   863     Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));

   864 }

   865 

   866 /* ===========================================================================

   867  * Send a stored block

   868  */

   869 void _tr_stored_block(

   870     deflate_state *s,

   871     charf *buf,       /* input block */

   872     ulg stored_len,   /* length of input block */

   873     int eof)          /* true if this is the last block for a file */

   874 {

   875     send_bits(s, (STORED_BLOCK<<1)+eof, 3);  /* send block type */

   876 #ifdef DEBUG

   877     s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;

   878     s->compressed_len += (stored_len + 4) << 3;

   879 #endif

   880     copy_block(s, buf, (unsigned)stored_len, 1); /* with header */

   881 }

   882 

   883 /* ===========================================================================

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

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

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

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

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

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

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

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

   892  * on one bit only.

   893  */

   894 void _tr_align(

   895     deflate_state *s)

   896 {

   897     send_bits(s, STATIC_TREES<<1, 3);

   898     send_code(s, END_BLOCK, static_ltree);

   899 #ifdef DEBUG

   900     s->compressed_len += 10L; /* 3 for block type, 7 for EOB */

   901 #endif

   902     bi_flush(s);

   903     /* Of the 10 bits for the empty block, we have already sent

   904      * (10 - bi_valid) bits. The lookahead for the last real code (before

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

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

   907      */

   908     if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {

   909         send_bits(s, STATIC_TREES<<1, 3);

   910         send_code(s, END_BLOCK, static_ltree);

   911 #ifdef DEBUG

   912         s->compressed_len += 10L;

   913 #endif

   914         bi_flush(s);

   915     }

   916     s->last_eob_len = 7;

   917 }

   918 

   919 /* ===========================================================================

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

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

   922  */

   923 void _tr_flush_block(

   924     deflate_state *s,

   925     charf *buf,       /* input block, or NULL if too old */

   926     ulg stored_len,   /* length of input block */

   927     int eof)          /* true if this is the last block for a file */

   928 {

   929     ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */

   930     int max_blindex = 0;  /* index of last bit length code of non zero freq */

   931 

   932     /* Build the Huffman trees unless a stored block is forced */

   933     if (s->level > 0) {

   934 

   935 	 /* Check if the file is ascii or binary */

   936 	if (s->data_type == Z_UNKNOWN) set_data_type(s);

   937 

   938 	/* Construct the literal and distance trees */

   939 	build_tree(s, (tree_desc *)(&(s->l_desc)));

   940 	Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,

   941 		s->static_len));

   942 

   943 	build_tree(s, (tree_desc *)(&(s->d_desc)));

   944 	Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,

   945 		s->static_len));

   946 	/* At this point, opt_len and static_len are the total bit lengths of

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

   948 	 */

   949 

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

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

   952 	 */

   953 	max_blindex = build_bl_tree(s);

   954 

   955 	/* Determine the best encoding. Compute first the block length in bytes*/

   956 	opt_lenb = (s->opt_len+3+7)>>3;

   957 	static_lenb = (s->static_len+3+7)>>3;

   958 

   959 	Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",

   960 		opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,

   961 		s->last_lit));

   962 

   963 	if (static_lenb <= opt_lenb) opt_lenb = static_lenb;

   964 

   965     } else {

   966         Assert(buf != (char*)0, "lost buf");

   967 	opt_lenb = static_lenb = stored_len + 5; /* force a stored block */

   968     }

   969 

   970 #ifdef FORCE_STORED

   971     if (buf != (char*)0) { /* force stored block */

   972 #else

   973     if (stored_len+4 <= opt_lenb && buf != (char*)0) {

   974                        /* 4: two words for the lengths */

   975 #endif

   976         /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.

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

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

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

   980          * transform a block into a stored block.

   981          */

   982         _tr_stored_block(s, buf, stored_len, eof);

   983 

   984 #ifdef FORCE_STATIC

   985     } else if (static_lenb >= 0) { /* force static trees */

   986 #else

   987     } else if (static_lenb == opt_lenb) {

   988 #endif

   989         send_bits(s, (STATIC_TREES<<1)+eof, 3);

   990         compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);

   991 #ifdef DEBUG

   992         s->compressed_len += 3 + s->static_len;

   993 #endif

   994     } else {

   995         send_bits(s, (DYN_TREES<<1)+eof, 3);

   996         send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,

   997                        max_blindex+1);

   998         compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);

   999 #ifdef DEBUG

  1000         s->compressed_len += 3 + s->opt_len;

  1001 #endif

  1002     }

  1003     Assert (s->compressed_len == s->bits_sent, "bad compressed size");

  1004     /* The above check is made mod 2^32, for files larger than 512 MB

  1005      * and uLong implemented on 32 bits.

  1006      */

  1007     init_block(s);

  1008 

  1009     if (eof) {

  1010         bi_windup(s);

  1011 #ifdef DEBUG

  1012         s->compressed_len += 7;  /* align on byte boundary */

  1013 #endif

  1014     }

  1015     Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,

  1016            s->compressed_len-7*eof));

  1017 }

  1018 

  1019 /* ===========================================================================

  1020  * Save the match info and tally the frequency counts. Return true if

  1021  * the current block must be flushed.

  1022  */

  1023 int _tr_tally (

  1024     deflate_state *s,

  1025     unsigned dist,  /* distance of matched string */

  1026     unsigned lc)    /* match length-MIN_MATCH or unmatched char (if dist==0) */

  1027 {

  1028     s->d_buf[s->last_lit] = (ush)dist;

  1029     s->l_buf[s->last_lit++] = (uch)lc;

  1030     if (dist == 0) {

  1031         /* lc is the unmatched char */

  1032         s->dyn_ltree[lc].Freq++;

  1033     } else {

  1034         s->matches++;

  1035         /* Here, lc is the match length - MIN_MATCH */

  1036         dist--;             /* dist = match distance - 1 */

  1037         Assert((ush)dist < (ush)MAX_DIST(s) &&

  1038                (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&

  1039                (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");

  1040 

  1041         s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;

  1042         s->dyn_dtree[d_code(dist)].Freq++;

  1043     }

  1044 

  1045 #ifdef TRUNCATE_BLOCK

  1046     /* Try to guess if it is profitable to stop the current block here */

  1047     if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {

  1048         /* Compute an upper bound for the compressed length */

  1049         ulg out_length = (ulg)s->last_lit*8L;

  1050         ulg in_length = (ulg)((long)s->strstart - s->block_start);

  1051         int dcode;

  1052         for (dcode = 0; dcode < D_CODES; dcode++) {

  1053             out_length += (ulg)s->dyn_dtree[dcode].Freq *

  1054                 (5L+extra_dbits[dcode]);

  1055         }

  1056         out_length >>= 3;

  1057         Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",

  1058                s->last_lit, in_length, out_length,

  1059                100L - out_length*100L/in_length));

  1060         if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;

  1061     }

  1062 #endif

  1063     return (s->last_lit == s->lit_bufsize-1);

  1064     /* We avoid equality with lit_bufsize because of wraparound at 64K

  1065      * on 16 bit machines and because stored blocks are restricted to

  1066      * 64K-1 bytes.

  1067      */

  1068 }

  1069 

  1070 /* ===========================================================================

  1071  * Send the block data compressed using the given Huffman trees

  1072  */

  1073 local void compress_block(

  1074     deflate_state *s,

  1075     ct_data *ltree, /* literal tree */

  1076     ct_data *dtree) /* distance tree */

  1077 {

  1078     unsigned dist;      /* distance of matched string */

  1079     int lc;             /* match length or unmatched char (if dist == 0) */

  1080     unsigned lx = 0;    /* running index in l_buf */

  1081     unsigned code;      /* the code to send */

  1082     int extra;          /* number of extra bits to send */

  1083 

  1084     if (s->last_lit != 0) do {

  1085         dist = s->d_buf[lx];

  1086         lc = s->l_buf[lx++];

  1087         if (dist == 0) {

  1088             send_code(s, lc, ltree); /* send a literal byte */

  1089             Tracecv(isgraph(lc), (stderr," '%c' ", lc));

  1090         } else {

  1091             /* Here, lc is the match length - MIN_MATCH */

  1092             code = _length_code[lc];

  1093             send_code(s, code+LITERALS+1, ltree); /* send the length code */

  1094             extra = extra_lbits[code];

  1095             if (extra != 0) {

  1096                 lc -= base_length[code];

  1097                 send_bits(s, lc, extra);       /* send the extra length bits */

  1098             }

  1099             dist--; /* dist is now the match distance - 1 */

  1100             code = d_code(dist);

  1101             Assert (code < D_CODES, "bad d_code");

  1102 

  1103             send_code(s, code, dtree);       /* send the distance code */

  1104             extra = extra_dbits[code];

  1105             if (extra != 0) {

  1106                 dist -= base_dist[code];

  1107                 send_bits(s, dist, extra);   /* send the extra distance bits */

  1108             }

  1109         } /* literal or match pair ? */

  1110 

  1111         /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */

  1112         Assert(s->pending < s->lit_bufsize + 2*lx, "pendingBuf overflow");

  1113 

  1114     } while (lx < s->last_lit);

  1115 

  1116     send_code(s, END_BLOCK, ltree);

  1117     s->last_eob_len = ltree[END_BLOCK].Len;

  1118 }

  1119 

  1120 /* ===========================================================================

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

  1122  * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.

  1123  * IN assertion: the fields freq of dyn_ltree are set and the total of all

  1124  * frequencies does not exceed 64K (to fit in an int on 16 bit machines).

  1125  */

  1126 local void set_data_type(

  1127     deflate_state *s)

  1128 {

  1129     int n = 0;

  1130     unsigned ascii_freq = 0;

  1131     unsigned bin_freq = 0;

  1132     while (n < 7)        bin_freq += s->dyn_ltree[n++].Freq;

  1133     while (n < 128)    ascii_freq += s->dyn_ltree[n++].Freq;

  1134     while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq;