1 /*

     2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     3  *

     4  * This code is free software; you can redistribute it and/or modify it

     5  * under the terms of the GNU General Public License version 2 only, as

     6  * published by the Free Software Foundation.  Oracle designates this

     7  * particular file as subject to the "Classpath" exception as provided

     8  * by Oracle in the LICENSE file that accompanied this code.

     9  *

    10  * This code is distributed in the hope that it will be useful, but WITHOUT

    11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    13  * version 2 for more details (a copy is included in the LICENSE file that

    14  * accompanied this code).

    15  *

    16  * You should have received a copy of the GNU General Public License version

    17  * 2 along with this work; if not, write to the Free Software Foundation,

    18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    19  *

    20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    21  * or visit www.oracle.com if you need additional information or have any

    22  * questions.

    23  */

    24 

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

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

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

    28  */

    29 

    30 /*

    31  *  ALGORITHM

    32  *

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

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

    35  *

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

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

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

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

    40  * in the deflate specification.

    41  *

    42  *  REFERENCES

    43  *

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

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

    46  *

    47  *      Storer, James A.

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

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

    50  *

    51  *      Sedgewick, R.

    52  *          Algorithms, p290.

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

    54  */

    55 

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

    57 

    58 /* #define GEN_TREES_H */

    59 

    60 #include "deflate.h"

    61 

    62 #ifdef DEBUG

    63 #  include <ctype.h>

    64 #endif

    65 

    66 /* ===========================================================================

    67  * Constants

    68  */

    69 

    70 #define MAX_BL_BITS 7

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

    72 

    73 #define END_BLOCK 256

    74 /* end of block literal code */

    75 

    76 #define REP_3_6      16

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

    78 

    79 #define REPZ_3_10    17

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

    81 

    82 #define REPZ_11_138  18

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

    84 

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

    86    = {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};

    87 

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

    89    = {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};

    90 

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

    92    = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};

    93 

    94 local const uch bl_order[BL_CODES]

    95    = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};

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

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

    98  */

    99 

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

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

   102  * more than 16 bits on some systems.)

   103  */

   104 

   105 /* ===========================================================================

   106  * Local data. These are initialized only once.

   107  */

   108 

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

   110 

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

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

   113 

   114 local ct_data static_ltree[L_CODES+2];

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

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

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

   118  * below).

   119  */

   120 

   121 local ct_data static_dtree[D_CODES];

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

   123  * 5 bits.)

   124  */

   125 

   126 uch _dist_code[DIST_CODE_LEN];

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

   128  * 3 .. 258, the last 256 values correspond to the top 8 bits of

   129  * the 15 bit distances.

   130  */

   131 

   132 uch _length_code[MAX_MATCH-MIN_MATCH+1];

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

   134 

   135 local int base_length[LENGTH_CODES];

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

   137 

   138 local int base_dist[D_CODES];

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

   140 

   141 #else

   142 #  include "trees.h"

   143 #endif /* GEN_TREES_H */

   144 

   145 struct static_tree_desc_s {

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

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

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

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

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

   151 };

   152 

   153 local static_tree_desc  static_l_desc =

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

   155 

   156 local static_tree_desc  static_d_desc =

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

   158 

   159 local static_tree_desc  static_bl_desc =

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

   161 

   162 /* ===========================================================================

   163  * Local (static) routines in this file.

   164  */

   165 

   166 local void tr_static_init OF((void));

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

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

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

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

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

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

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

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

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

   176                               int blcodes));

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

   178                               ct_data *dtree));

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

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

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

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

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

   184                               int header));

   185 

   186 #ifdef GEN_TREES_H

   187 local void gen_trees_header OF((void));

   188 #endif

   189 

   190 #ifndef DEBUG

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

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

   193 

   194 #else /* DEBUG */

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

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

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

   198 #endif

   199 

   200 /* ===========================================================================

   201  * Output a short LSB first on the stream.

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

   203  */

   204 #define put_short(s, w) { \

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

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

   207 }

   208 

   209 /* ===========================================================================

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

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

   212  */

   213 #ifdef DEBUG

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

   215 

   216 local void send_bits(s, value, length)

   217     deflate_state *s;

   218     int value;  /* value to send */

   219     int length; /* number of bits */

   220 {

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

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

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

   224 

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

   226      * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))

   227      * unused bits in value.

   228      */

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

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

   231         put_short(s, s->bi_buf);

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

   233         s->bi_valid += length - Buf_size;

   234     } else {

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

   236         s->bi_valid += length;

   237     }

   238 }

   239 #else /* !DEBUG */

   240 

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

   242 { int len = length;\

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

   244     int val = value;\

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

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

   247     s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\

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

   249   } else {\

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

   251     s->bi_valid += len;\

   252   }\

   253 }

   254 #endif /* DEBUG */

   255 

   256 

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

   258 

   259 /* ===========================================================================

   260  * Initialize the various 'constant' tables.

   261  */

   262 local void tr_static_init()

   263 {

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

   265     static int static_init_done = 0;

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

   267     int bits;     /* bit counter */

   268     int length;   /* length value */

   269     int code;     /* code value */

   270     int dist;     /* distance index */

   271     ush bl_count[MAX_BITS+1];

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

   273 

   274     if (static_init_done) return;

   275 

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

   277     static_l_desc.static_tree = static_ltree;

   278     static_l_desc.extra_bits = extra_lbits;

   279     static_d_desc.static_tree = static_dtree;

   280     static_d_desc.extra_bits = extra_dbits;

   281     static_bl_desc.extra_bits = extra_blbits;

   282 

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

   284     length = 0;

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

   286         base_length[code] = length;

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

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

   289         }

   290     }

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

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

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

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

   295      */

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

   297 

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

   299     dist = 0;

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

   301         base_dist[code] = dist;

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

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

   304         }

   305     }

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

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

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

   309         base_dist[code] = dist << 7;

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

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

   312         }

   313     }

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

   315 

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

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

   318     n = 0;

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

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

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

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

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

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

   325      * all ones)

   326      */

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

   328 

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

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

   331         static_dtree[n].Len = 5;

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

   333     }

   334     static_init_done = 1;

   335 

   336 #  ifdef GEN_TREES_H

   337     gen_trees_header();

   338 #  endif

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

   340 }

   341 

   342 /* ===========================================================================

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

   344  */

   345 #ifdef GEN_TREES_H

   346 #  ifndef DEBUG

   347 #    include <stdio.h>

   348 #  endif

   349 

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

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

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

   353 

   354 void gen_trees_header()

   355 {

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

   357     int i;

   358 

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

   360     fprintf(header,

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

   362 

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

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

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

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

   367     }

   368 

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

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

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

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

   373     }

   374 

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

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

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

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

   379     }

   380 

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

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

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

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

   385     }

   386 

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

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

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

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

   391     }

   392 

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

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

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

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

   397     }

   398 

   399     fclose(header);

   400 }

   401 #endif /* GEN_TREES_H */

   402 

   403 /* ===========================================================================

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

   405  */

   406 void _tr_init(s)

   407     deflate_state *s;

   408 {

   409     tr_static_init();

   410 

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

   412     s->l_desc.stat_desc = &static_l_desc;

   413 

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

   415     s->d_desc.stat_desc = &static_d_desc;

   416 

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

   418     s->bl_desc.stat_desc = &static_bl_desc;

   419 

   420     s->bi_buf = 0;

   421     s->bi_valid = 0;

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

   423 #ifdef DEBUG

   424     s->compressed_len = 0L;

   425     s->bits_sent = 0L;

   426 #endif

   427 

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

   429     init_block(s);

   430 }

   431 

   432 /* ===========================================================================

   433  * Initialize a new block.

   434  */

   435 local void init_block(s)

   436     deflate_state *s;

   437 {

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

   439 

   440     /* Initialize the trees. */

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

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

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

   444 

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

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

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

   448 }

   449 

   450 #define SMALLEST 1

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

   452 

   453 

   454 /* ===========================================================================

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

   456  * one less element. Updates heap and heap_len.

   457  */

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

   459 {\

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

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

   462     pqdownheap(s, tree, SMALLEST); \

   463 }

   464 

   465 /* ===========================================================================

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

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

   468  */

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

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

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

   472 

   473 /* ===========================================================================

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

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

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

   477  * two sons).

   478  */

   479 local void pqdownheap(s, tree, k)

   480     deflate_state *s;

   481     ct_data *tree;  /* the tree to restore */

   482     int k;               /* node to move down */

   483 {

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

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

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

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

   488         if (j < s->heap_len &&

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

   490             j++;

   491         }

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

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

   494 

   495         /* Exchange v with the smallest son */

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

   497 

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

   499         j <<= 1;

   500     }

   501     s->heap[k] = v;

   502 }

   503 

   504 /* ===========================================================================

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

   506  * for the current block.

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

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

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

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

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

   512  *     not null.

   513  */

   514 local void gen_bitlen(s, desc)

   515     deflate_state *s;

   516     tree_desc *desc;    /* the tree descriptor */

   517 {

   518     ct_data *tree        = desc->dyn_tree;

   519     int max_code         = desc->max_code;

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

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

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

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

   524     int h;              /* heap index */

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

   526     int bits;           /* bit length */

   527     int xbits;          /* extra bits */

   528     ush f;              /* frequency */

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

   530 

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

   532 

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

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

   535      */

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

   537 

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

   539         n = s->heap[h];

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

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

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

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

   544 

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

   546 

   547         s->bl_count[bits]++;

   548         xbits = 0;

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

   550         f = tree[n].Freq;

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

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

   553     }

   554     if (overflow == 0) return;

   555 

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

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

   558 

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

   560     do {

   561         bits = max_length-1;

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

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

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

   565         s->bl_count[max_length]--;

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

   567          * but this does not affect bl_count[max_length]

   568          */

   569         overflow -= 2;

   570     } while (overflow > 0);

   571 

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

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

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

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

   576      */

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

   578         n = s->bl_count[bits];

   579         while (n != 0) {

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

   581             if (m > max_code) continue;

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

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

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

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

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

   587             }

   588             n--;

   589         }

   590     }

   591 }

   592 

   593 /* ===========================================================================

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

   595  * optimal).

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

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

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

   599  *     zero code length.

   600  */

   601 local void gen_codes (tree, max_code, bl_count)

   602     ct_data *tree;             /* the tree to decorate */

   603     int max_code;              /* largest code with non zero frequency */

   604     ushf *bl_count;            /* number of codes at each bit length */

   605 {

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

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

   608     int bits;                  /* bit index */

   609     int n;                     /* code index */

   610 

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

   612      * without bit reversal.

   613      */

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

   615         next_code[bits] = code = (code + bl_count[bits-1]) << 1;

   616     }

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

   618      * must be all ones.

   619      */

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

   621             "inconsistent bit counts");

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

   623 

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

   625         int len = tree[n].Len;

   626         if (len == 0) continue;

   627         /* Now reverse the bits */

   628         tree[n].Code = bi_reverse(next_code[len]++, len);

   629 

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

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

   632     }

   633 }

   634 

   635 /* ===========================================================================

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

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

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

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

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

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

   642  */

   643 local void build_tree(s, desc)

   644     deflate_state *s;

   645     tree_desc *desc; /* the tree descriptor */

   646 {

   647     ct_data *tree         = desc->dyn_tree;

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

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

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

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

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

   653 

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

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

   656      * heap[0] is not used.

   657      */

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

   659 

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

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

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

   663             s->depth[n] = 0;

   664         } else {

   665             tree[n].Len = 0;

   666         }

   667     }

   668 

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

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

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

   672      * two codes of non zero frequency.

   673      */

   674     while (s->heap_len < 2) {

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

   676         tree[node].Freq = 1;

   677         s->depth[node] = 0;

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

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

   680     }

   681     desc->max_code = max_code;

   682 

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

   684      * establish sub-heaps of increasing lengths:

   685      */

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

   687 

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

   689      * frequent nodes.

   690      */

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

   692     do {

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

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

   695 

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

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

   698 

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

   700         tree[node].Freq = tree[n].Freq + tree[m].Freq;

   701         s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?

   702                                 s->depth[n] : s->depth[m]) + 1);

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

   704 #ifdef DUMP_BL_TREE

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

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

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

   708         }

   709 #endif

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

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

   712         pqdownheap(s, tree, SMALLEST);

   713 

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

   715 

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

   717 

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

   719      * generate the bit lengths.

   720      */

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

   722 

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

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

   725 }

   726 

   727 /* ===========================================================================

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

   729  * in the bit length tree.

   730  */

   731 local void scan_tree (s, tree, max_code)

   732     deflate_state *s;

   733     ct_data *tree;   /* the tree to be scanned */

   734     int max_code;    /* and its largest code of non zero frequency */

   735 {

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

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

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

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

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

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

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

   743 

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

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

   746 

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

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

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

   750             continue;

   751         } else if (count < min_count) {

   752             s->bl_tree[curlen].Freq += count;

   753         } else if (curlen != 0) {

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

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

   756         } else if (count <= 10) {

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

   758         } else {

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

   760         }

   761         count = 0; prevlen = curlen;

   762         if (nextlen == 0) {

   763             max_count = 138, min_count = 3;

   764         } else if (curlen == nextlen) {

   765             max_count = 6, min_count = 3;

   766         } else {

   767             max_count = 7, min_count = 4;

   768         }

   769     }

   770 }

   771 

   772 /* ===========================================================================

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

   774  * bl_tree.

   775  */

   776 local void send_tree (s, tree, max_code)

   777     deflate_state *s;

   778     ct_data *tree; /* the tree to be scanned */

   779     int max_code;       /* and its largest code of non zero frequency */

   780 {

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

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

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

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

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

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

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

   788 

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

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

   791 

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

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

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

   795             continue;

   796         } else if (count < min_count) {

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

   798 

   799         } else if (curlen != 0) {

   800             if (curlen != prevlen) {

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

   802             }

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

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

   805 

   806         } else if (count <= 10) {

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

   808 

   809         } else {

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

   811         }

   812         count = 0; prevlen = curlen;

   813         if (nextlen == 0) {

   814             max_count = 138, min_count = 3;

   815         } else if (curlen == nextlen) {

   816             max_count = 6, min_count = 3;

   817         } else {

   818             max_count = 7, min_count = 4;

   819         }

   820     }

   821 }

   822 

   823 /* ===========================================================================

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

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

   826  */

   827 local int build_bl_tree(s)

   828     deflate_state *s;

   829 {

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

   831 

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

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

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

   835 

   836     /* Build the bit length tree: */

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

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

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

   840      */

   841 

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

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

   844      * 3 but the actual value used is 4.)

   845      */

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

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

   848     }

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

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

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

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

   853 

   854     return max_blindex;

   855 }

   856 

   857 /* ===========================================================================

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

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

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

   861  */

   862 local void send_all_trees(s, lcodes, dcodes, blcodes)

   863     deflate_state *s;

   864     int lcodes, dcodes, blcodes; /* number of codes for each tree */

   865 {

   866     int rank;                    /* index in bl_order */

   867 

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

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

   870             "too many codes");

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

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

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

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

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

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

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

   878     }

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

   880 

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

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

   883 

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

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

   886 }

   887 

   888 /* ===========================================================================

   889  * Send a stored block

   890  */

   891 void _tr_stored_block(s, buf, stored_len, eof)

   892     deflate_state *s;

   893     charf *buf;       /* input block */

   894     ulg stored_len;   /* length of input block */

   895     int eof;          /* true if this is the last block for a file */

   896 {

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

   898 #ifdef DEBUG

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

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

   901 #endif

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

   903 }

   904 

   905 /* ===========================================================================

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

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

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

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

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

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

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

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

   914  * on one bit only.

   915  */

   916 void _tr_align(s)

   917     deflate_state *s;

   918 {

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

   920     send_code(s, END_BLOCK, static_ltree);

   921 #ifdef DEBUG

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

   923 #endif

   924     bi_flush(s);

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

   926      * (10 - bi_valid) bits. The lookahead for the last real code (before

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

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

   929      */

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

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

   932         send_code(s, END_BLOCK, static_ltree);

   933 #ifdef DEBUG

   934         s->compressed_len += 10L;

   935 #endif

   936         bi_flush(s);

   937     }

   938     s->last_eob_len = 7;

   939 }

   940 

   941 /* ===========================================================================

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

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

   944  */

   945 void _tr_flush_block(s, buf, stored_len, eof)

   946     deflate_state *s;

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

   948     ulg stored_len;   /* length of input block */

   949     int eof;          /* true if this is the last block for a file */

   950 {

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

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

   953 

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

   955     if (s->level > 0) {

   956 

   957         /* Check if the file is binary or text */

   958         if (stored_len > 0 && s->strm->data_type == Z_UNKNOWN)

   959             set_data_type(s);

   960 

   961         /* Construct the literal and distance trees */

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

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

   964                 s->static_len));

   965 

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

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

   968                 s->static_len));

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

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

   971          */

   972 

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

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

   975          */

   976         max_blindex = build_bl_tree(s);

   977 

   978         /* Determine the best encoding. Compute the block lengths in bytes. */

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

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

   981 

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

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

   984                 s->last_lit));

   985 

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

   987 

   988     } else {

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

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

   991     }

   992 

   993 #ifdef FORCE_STORED

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

   995 #else

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

   997                        /* 4: two words for the lengths */

   998 #endif

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

  1000          * Otherwise we can't have processed more than WSIZE input bytes since

  1001          * the last block flush, because compression would have been

  1002          * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to

  1003          * transform a block into a stored block.

  1004          */

  1005         _tr_stored_block(s, buf, stored_len, eof);

  1006 

  1007 #ifdef FORCE_STATIC

  1008     } else if (static_lenb >= 0) { /* force static trees */

  1009 #else

  1010     } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {

  1011 #endif

  1012         send_bits(s, (STATIC_TREES<<1)+eof, 3);

  1013         compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);

  1014 #ifdef DEBUG

  1015         s->compressed_len += 3 + s->static_len;

  1016 #endif

  1017     } else {

  1018         send_bits(s, (DYN_TREES<<1)+eof, 3);

  1019         send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,

  1020                        max_blindex+1);

  1021         compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);

  1022 #ifdef DEBUG

  1023         s->compressed_len += 3 + s->opt_len;

  1024 #endif

  1025     }

  1026     Assert (s->compressed_len == s->bits_sent, "bad compressed size");

  1027     /* The above check is made mod 2^32, for files larger than 512 MB

  1028      * and uLong implemented on 32 bits.

  1029      */

  1030     init_block(s);

  1031 

  1032     if (eof) {

  1033         bi_windup(s);

  1034 #ifdef DEBUG

  1035         s->compressed_len += 7;  /* align on byte boundary */

  1036 #endif

  1037     }

  1038     Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,

  1039            s->compressed_len-7*eof));

  1040 }

  1041 

  1042 /* ===========================================================================

  1043  * Save the match info and tally the frequency counts. Return true if

  1044  * the current block must be flushed.

  1045  */

  1046 int _tr_tally (s, dist, lc)

  1047     deflate_state *s;

  1048     unsigned dist;  /* distance of matched string */

  1049     unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */

  1050 {

  1051     s->d_buf[s->last_lit] = (ush)dist;

  1052     s->l_buf[s->last_lit++] = (uch)lc;

  1053     if (dist == 0) {

  1054         /* lc is the unmatched char */

  1055         s->dyn_ltree[lc].Freq++;

  1056     } else {

  1057         s->matches++;

  1058         /* Here, lc is the match length - MIN_MATCH */

  1059         dist--;             /* dist = match distance - 1 */

  1060         Assert((ush)dist < (ush)MAX_DIST(s) &&

  1061                (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&

  1062                (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");

  1063 

  1064         s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;

  1065         s->dyn_dtree[d_code(dist)].Freq++;

  1066     }

  1067 

  1068 #ifdef TRUNCATE_BLOCK

  1069     /* Try to guess if it is profitable to stop the current block here */

  1070     if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {

  1071         /* Compute an upper bound for the compressed length */

  1072         ulg out_length = (ulg)s->last_lit*8L;

  1073         ulg in_length = (ulg)((long)s->strstart - s->block_start);

  1074         int dcode;

  1075         for (dcode = 0; dcode < D_CODES; dcode++) {

  1076             out_length += (ulg)s->dyn_dtree[dcode].Freq *

  1077                 (5L+extra_dbits[dcode]);

  1078         }

  1079         out_length >>= 3;

  1080         Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",

  1081                s->last_lit, in_length, out_length,

  1082                100L - out_length*100L/in_length));

  1083         if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;

  1084     }

  1085 #endif

  1086     return (s->last_lit == s->lit_bufsize-1);

  1087     /* We avoid equality with lit_bufsize because of wraparound at 64K

  1088      * on 16 bit machines and because stored blocks are restricted to

  1089      * 64K-1 bytes.

  1090      */

  1091 }

  1092 

  1093 /* ===========================================================================

  1094  * Send the block data compressed using the given Huffman trees

  1095  */

  1096 local void compress_block(s, ltree, dtree)

  1097     deflate_state *s;

  1098     ct_data *ltree; /* literal tree */

  1099     ct_data *dtree; /* distance tree */

  1100 {

  1101     unsigned dist;      /* distance of matched string */

  1102     int lc;             /* match length or unmatched char (if dist == 0) */

  1103     unsigned lx = 0;    /* running index in l_buf */

  1104     unsigned code;      /* the code to send */

  1105     int extra;          /* number of extra bits to send */

  1106 

  1107     if (s->last_lit != 0) do {

  1108         dist = s->d_buf[lx];

  1109         lc = s->l_buf[lx++];

  1110         if (dist == 0) {

  1111             send_code(s, lc, ltree); /* send a literal byte */

  1112             Tracecv(isgraph(lc), (stderr," '%c' ", lc));

  1113         } else {

  1114             /* Here, lc is the match length - MIN_MATCH */

  1115             code = _length_code[lc];

  1116             send_code(s, code+LITERALS+1, ltree); /* send the length code */

  1117             extra = extra_lbits[code];

  1118             if (extra != 0) {

  1119                 lc -= base_length[code];

  1120                 send_bits(s, lc, extra);       /* send the extra length bits */

  1121             }

  1122             dist--; /* dist is now the match distance - 1 */

  1123             code = d_code(dist);

  1124             Assert (code < D_CODES, "bad d_code");

  1125 

  1126             send_code(s, code, dtree);       /* send the distance code */

  1127             extra = extra_dbits[code];

  1128             if (extra != 0) {

  1129                 dist -= base_dist[code];

  1130                 send_bits(s, dist, extra);   /* send the extra distance bits */

  1131             }

  1132         } /* literal or match pair ? */

  1133 

  1134         /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */