symbian-qemu-0.9.1-12/python-2.6.1/Modules/zlib/trees.c
changeset 1 2fb8b9db1c86
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0:ffa851df0825 1:2fb8b9db1c86
       
     1 /* trees.c -- output deflated data using Huffman coding
       
     2  * Copyright (C) 1995-2005 Jean-loup Gailly
       
     3  * For conditions of distribution and use, see copyright notice in zlib.h
       
     4  */
       
     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 "deflate.h"
       
    37 
       
    38 #ifdef DEBUG
       
    39 #  include <ctype.h>
       
    40 #endif
       
    41 
       
    42 /* ===========================================================================
       
    43  * Constants
       
    44  */
       
    45 
       
    46 #define MAX_BL_BITS 7
       
    47 /* Bit length codes must not exceed MAX_BL_BITS bits */
       
    48 
       
    49 #define END_BLOCK 256
       
    50 /* end of block literal code */
       
    51 
       
    52 #define REP_3_6      16
       
    53 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
       
    54 
       
    55 #define REPZ_3_10    17
       
    56 /* repeat a zero length 3-10 times  (3 bits of repeat count) */
       
    57 
       
    58 #define REPZ_11_138  18
       
    59 /* repeat a zero length 11-138 times  (7 bits of repeat count) */
       
    60 
       
    61 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
       
    62    = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};
       
    63 
       
    64 local const int extra_dbits[D_CODES] /* extra bits for each distance code */
       
    65    = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
       
    66 
       
    67 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
       
    68    = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
       
    69 
       
    70 local const uch bl_order[BL_CODES]
       
    71    = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
       
    72 /* The lengths of the bit length codes are sent in order of decreasing
       
    73  * probability, to avoid transmitting the lengths for unused bit length codes.
       
    74  */
       
    75 
       
    76 #define Buf_size (8 * 2*sizeof(char))
       
    77 /* Number of bits used within bi_buf. (bi_buf might be implemented on
       
    78  * more than 16 bits on some systems.)
       
    79  */
       
    80 
       
    81 /* ===========================================================================
       
    82  * Local data. These are initialized only once.
       
    83  */
       
    84 
       
    85 #define DIST_CODE_LEN  512 /* see definition of array dist_code below */
       
    86 
       
    87 #if defined(GEN_TREES_H) || !defined(STDC)
       
    88 /* non ANSI compilers may not accept trees.h */
       
    89 
       
    90 local ct_data static_ltree[L_CODES+2];
       
    91 /* The static literal tree. Since the bit lengths are imposed, there is no
       
    92  * need for the L_CODES extra codes used during heap construction. However
       
    93  * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
       
    94  * below).
       
    95  */
       
    96 
       
    97 local ct_data static_dtree[D_CODES];
       
    98 /* The static distance tree. (Actually a trivial tree since all codes use
       
    99  * 5 bits.)
       
   100  */
       
   101 
       
   102 uch _dist_code[DIST_CODE_LEN];
       
   103 /* Distance codes. The first 256 values correspond to the distances
       
   104  * 3 .. 258, the last 256 values correspond to the top 8 bits of
       
   105  * the 15 bit distances.
       
   106  */
       
   107 
       
   108 uch _length_code[MAX_MATCH-MIN_MATCH+1];
       
   109 /* length code for each normalized match length (0 == MIN_MATCH) */
       
   110 
       
   111 local int base_length[LENGTH_CODES];
       
   112 /* First normalized length for each code (0 = MIN_MATCH) */
       
   113 
       
   114 local int base_dist[D_CODES];
       
   115 /* First normalized distance for each code (0 = distance of 1) */
       
   116 
       
   117 #else
       
   118 #  include "trees.h"
       
   119 #endif /* GEN_TREES_H */
       
   120 
       
   121 struct static_tree_desc_s {
       
   122     const ct_data *static_tree;  /* static tree or NULL */
       
   123     const intf *extra_bits;      /* extra bits for each code or NULL */
       
   124     int     extra_base;          /* base index for extra_bits */
       
   125     int     elems;               /* max number of elements in the tree */
       
   126     int     max_length;          /* max bit length for the codes */
       
   127 };
       
   128 
       
   129 local static_tree_desc  static_l_desc =
       
   130 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
       
   131 
       
   132 local static_tree_desc  static_d_desc =
       
   133 {static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};
       
   134 
       
   135 local static_tree_desc  static_bl_desc =
       
   136 {(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
       
   137 
       
   138 /* ===========================================================================
       
   139  * Local (static) routines in this file.
       
   140  */
       
   141 
       
   142 local void tr_static_init OF((void));
       
   143 local void init_block     OF((deflate_state *s));
       
   144 local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));
       
   145 local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));
       
   146 local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));
       
   147 local void build_tree     OF((deflate_state *s, tree_desc *desc));
       
   148 local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));
       
   149 local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));
       
   150 local int  build_bl_tree  OF((deflate_state *s));
       
   151 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
       
   152                               int blcodes));
       
   153 local void compress_block OF((deflate_state *s, ct_data *ltree,
       
   154                               ct_data *dtree));
       
   155 local void set_data_type  OF((deflate_state *s));
       
   156 local unsigned bi_reverse OF((unsigned value, int length));
       
   157 local void bi_windup      OF((deflate_state *s));
       
   158 local void bi_flush       OF((deflate_state *s));
       
   159 local void copy_block     OF((deflate_state *s, charf *buf, unsigned len,
       
   160                               int header));
       
   161 
       
   162 #ifdef GEN_TREES_H
       
   163 local void gen_trees_header OF((void));
       
   164 #endif
       
   165 
       
   166 #ifndef DEBUG
       
   167 #  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
       
   168    /* Send a code of the given tree. c and tree must not have side effects */
       
   169 
       
   170 #else /* DEBUG */
       
   171 #  define send_code(s, c, tree) \
       
   172      { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
       
   173        send_bits(s, tree[c].Code, tree[c].Len); }
       
   174 #endif
       
   175 
       
   176 /* ===========================================================================
       
   177  * Output a short LSB first on the stream.
       
   178  * IN assertion: there is enough room in pendingBuf.
       
   179  */
       
   180 #define put_short(s, w) { \
       
   181     put_byte(s, (uch)((w) & 0xff)); \
       
   182     put_byte(s, (uch)((ush)(w) >> 8)); \
       
   183 }
       
   184 
       
   185 /* ===========================================================================
       
   186  * Send a value on a given number of bits.
       
   187  * IN assertion: length <= 16 and value fits in length bits.
       
   188  */
       
   189 #ifdef DEBUG
       
   190 local void send_bits      OF((deflate_state *s, int value, int length));
       
   191 
       
   192 local void send_bits(s, value, length)
       
   193     deflate_state *s;
       
   194     int value;  /* value to send */
       
   195     int length; /* number of bits */
       
   196 {
       
   197     Tracevv((stderr," l %2d v %4x ", length, value));
       
   198     Assert(length > 0 && length <= 15, "invalid length");
       
   199     s->bits_sent += (ulg)length;
       
   200 
       
   201     /* If not enough room in bi_buf, use (valid) bits from bi_buf and
       
   202      * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
       
   203      * unused bits in value.
       
   204      */
       
   205     if (s->bi_valid > (int)Buf_size - length) {
       
   206         s->bi_buf |= (value << s->bi_valid);
       
   207         put_short(s, s->bi_buf);
       
   208         s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
       
   209         s->bi_valid += length - Buf_size;
       
   210     } else {
       
   211         s->bi_buf |= value << s->bi_valid;
       
   212         s->bi_valid += length;
       
   213     }
       
   214 }
       
   215 #else /* !DEBUG */
       
   216 
       
   217 #define send_bits(s, value, length) \
       
   218 { int len = length;\
       
   219   if (s->bi_valid > (int)Buf_size - len) {\
       
   220     int val = value;\
       
   221     s->bi_buf |= (val << s->bi_valid);\
       
   222     put_short(s, s->bi_buf);\
       
   223     s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
       
   224     s->bi_valid += len - Buf_size;\
       
   225   } else {\
       
   226     s->bi_buf |= (value) << s->bi_valid;\
       
   227     s->bi_valid += len;\
       
   228   }\
       
   229 }
       
   230 #endif /* DEBUG */
       
   231 
       
   232 
       
   233 /* the arguments must not have side effects */
       
   234 
       
   235 /* ===========================================================================
       
   236  * Initialize the various 'constant' tables.
       
   237  */
       
   238 local void tr_static_init()
       
   239 {
       
   240 #if defined(GEN_TREES_H) || !defined(STDC)
       
   241     static int static_init_done = 0;
       
   242     int n;        /* iterates over tree elements */
       
   243     int bits;     /* bit counter */
       
   244     int length;   /* length value */
       
   245     int code;     /* code value */
       
   246     int dist;     /* distance index */
       
   247     ush bl_count[MAX_BITS+1];
       
   248     /* number of codes at each bit length for an optimal tree */
       
   249 
       
   250     if (static_init_done) return;
       
   251 
       
   252     /* For some embedded targets, global variables are not initialized: */
       
   253     static_l_desc.static_tree = static_ltree;
       
   254     static_l_desc.extra_bits = extra_lbits;
       
   255     static_d_desc.static_tree = static_dtree;
       
   256     static_d_desc.extra_bits = extra_dbits;
       
   257     static_bl_desc.extra_bits = extra_blbits;
       
   258 
       
   259     /* Initialize the mapping length (0..255) -> length code (0..28) */
       
   260     length = 0;
       
   261     for (code = 0; code < LENGTH_CODES-1; code++) {
       
   262         base_length[code] = length;
       
   263         for (n = 0; n < (1<<extra_lbits[code]); n++) {
       
   264             _length_code[length++] = (uch)code;
       
   265         }
       
   266     }
       
   267     Assert (length == 256, "tr_static_init: length != 256");
       
   268     /* Note that the length 255 (match length 258) can be represented
       
   269      * in two different ways: code 284 + 5 bits or code 285, so we
       
   270      * overwrite length_code[255] to use the best encoding:
       
   271      */
       
   272     _length_code[length-1] = (uch)code;
       
   273 
       
   274     /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
       
   275     dist = 0;
       
   276     for (code = 0 ; code < 16; code++) {
       
   277         base_dist[code] = dist;
       
   278         for (n = 0; n < (1<<extra_dbits[code]); n++) {
       
   279             _dist_code[dist++] = (uch)code;
       
   280         }
       
   281     }
       
   282     Assert (dist == 256, "tr_static_init: dist != 256");
       
   283     dist >>= 7; /* from now on, all distances are divided by 128 */
       
   284     for ( ; code < D_CODES; code++) {
       
   285         base_dist[code] = dist << 7;
       
   286         for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
       
   287             _dist_code[256 + dist++] = (uch)code;
       
   288         }
       
   289     }
       
   290     Assert (dist == 256, "tr_static_init: 256+dist != 512");
       
   291 
       
   292     /* Construct the codes of the static literal tree */
       
   293     for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
       
   294     n = 0;
       
   295     while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
       
   296     while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
       
   297     while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
       
   298     while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
       
   299     /* Codes 286 and 287 do not exist, but we must include them in the
       
   300      * tree construction to get a canonical Huffman tree (longest code
       
   301      * all ones)
       
   302      */
       
   303     gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
       
   304 
       
   305     /* The static distance tree is trivial: */
       
   306     for (n = 0; n < D_CODES; n++) {
       
   307         static_dtree[n].Len = 5;
       
   308         static_dtree[n].Code = bi_reverse((unsigned)n, 5);
       
   309     }
       
   310     static_init_done = 1;
       
   311 
       
   312 #  ifdef GEN_TREES_H
       
   313     gen_trees_header();
       
   314 #  endif
       
   315 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
       
   316 }
       
   317 
       
   318 /* ===========================================================================
       
   319  * Genererate the file trees.h describing the static trees.
       
   320  */
       
   321 #ifdef GEN_TREES_H
       
   322 #  ifndef DEBUG
       
   323 #    include <stdio.h>
       
   324 #  endif
       
   325 
       
   326 #  define SEPARATOR(i, last, width) \
       
   327       ((i) == (last)? "\n};\n\n" :    \
       
   328        ((i) % (width) == (width)-1 ? ",\n" : ", "))
       
   329 
       
   330 void gen_trees_header()
       
   331 {
       
   332     FILE *header = fopen("trees.h", "w");
       
   333     int i;
       
   334 
       
   335     Assert (header != NULL, "Can't open trees.h");
       
   336     fprintf(header,
       
   337             "/* header created automatically with -DGEN_TREES_H */\n\n");
       
   338 
       
   339     fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
       
   340     for (i = 0; i < L_CODES+2; i++) {
       
   341         fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
       
   342                 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
       
   343     }
       
   344 
       
   345     fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
       
   346     for (i = 0; i < D_CODES; i++) {
       
   347         fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
       
   348                 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
       
   349     }
       
   350 
       
   351     fprintf(header, "const uch _dist_code[DIST_CODE_LEN] = {\n");
       
   352     for (i = 0; i < DIST_CODE_LEN; i++) {
       
   353         fprintf(header, "%2u%s", _dist_code[i],
       
   354                 SEPARATOR(i, DIST_CODE_LEN-1, 20));
       
   355     }
       
   356 
       
   357     fprintf(header, "const uch _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
       
   358     for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
       
   359         fprintf(header, "%2u%s", _length_code[i],
       
   360                 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
       
   361     }
       
   362 
       
   363     fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
       
   364     for (i = 0; i < LENGTH_CODES; i++) {
       
   365         fprintf(header, "%1u%s", base_length[i],
       
   366                 SEPARATOR(i, LENGTH_CODES-1, 20));
       
   367     }
       
   368 
       
   369     fprintf(header, "local const int base_dist[D_CODES] = {\n");
       
   370     for (i = 0; i < D_CODES; i++) {
       
   371         fprintf(header, "%5u%s", base_dist[i],
       
   372                 SEPARATOR(i, D_CODES-1, 10));
       
   373     }
       
   374 
       
   375     fclose(header);
       
   376 }
       
   377 #endif /* GEN_TREES_H */
       
   378 
       
   379 /* ===========================================================================
       
   380  * Initialize the tree data structures for a new zlib stream.
       
   381  */
       
   382 void _tr_init(s)
       
   383     deflate_state *s;
       
   384 {
       
   385     tr_static_init();
       
   386 
       
   387     s->l_desc.dyn_tree = s->dyn_ltree;
       
   388     s->l_desc.stat_desc = &static_l_desc;
       
   389 
       
   390     s->d_desc.dyn_tree = s->dyn_dtree;
       
   391     s->d_desc.stat_desc = &static_d_desc;
       
   392 
       
   393     s->bl_desc.dyn_tree = s->bl_tree;
       
   394     s->bl_desc.stat_desc = &static_bl_desc;
       
   395 
       
   396     s->bi_buf = 0;
       
   397     s->bi_valid = 0;
       
   398     s->last_eob_len = 8; /* enough lookahead for inflate */
       
   399 #ifdef DEBUG
       
   400     s->compressed_len = 0L;
       
   401     s->bits_sent = 0L;
       
   402 #endif
       
   403 
       
   404     /* Initialize the first block of the first file: */
       
   405     init_block(s);
       
   406 }
       
   407 
       
   408 /* ===========================================================================
       
   409  * Initialize a new block.
       
   410  */
       
   411 local void init_block(s)
       
   412     deflate_state *s;
       
   413 {
       
   414     int n; /* iterates over tree elements */
       
   415 
       
   416     /* Initialize the trees. */
       
   417     for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
       
   418     for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
       
   419     for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
       
   420 
       
   421     s->dyn_ltree[END_BLOCK].Freq = 1;
       
   422     s->opt_len = s->static_len = 0L;
       
   423     s->last_lit = s->matches = 0;
       
   424 }
       
   425 
       
   426 #define SMALLEST 1
       
   427 /* Index within the heap array of least frequent node in the Huffman tree */
       
   428 
       
   429 
       
   430 /* ===========================================================================
       
   431  * Remove the smallest element from the heap and recreate the heap with
       
   432  * one less element. Updates heap and heap_len.
       
   433  */
       
   434 #define pqremove(s, tree, top) \
       
   435 {\
       
   436     top = s->heap[SMALLEST]; \
       
   437     s->heap[SMALLEST] = s->heap[s->heap_len--]; \
       
   438     pqdownheap(s, tree, SMALLEST); \
       
   439 }
       
   440 
       
   441 /* ===========================================================================
       
   442  * Compares to subtrees, using the tree depth as tie breaker when
       
   443  * the subtrees have equal frequency. This minimizes the worst case length.
       
   444  */
       
   445 #define smaller(tree, n, m, depth) \
       
   446    (tree[n].Freq < tree[m].Freq || \
       
   447    (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
       
   448 
       
   449 /* ===========================================================================
       
   450  * Restore the heap property by moving down the tree starting at node k,
       
   451  * exchanging a node with the smallest of its two sons if necessary, stopping
       
   452  * when the heap property is re-established (each father smaller than its
       
   453  * two sons).
       
   454  */
       
   455 local void pqdownheap(s, tree, k)
       
   456     deflate_state *s;
       
   457     ct_data *tree;  /* the tree to restore */
       
   458     int k;               /* node to move down */
       
   459 {
       
   460     int v = s->heap[k];
       
   461     int j = k << 1;  /* left son of k */
       
   462     while (j <= s->heap_len) {
       
   463         /* Set j to the smallest of the two sons: */
       
   464         if (j < s->heap_len &&
       
   465             smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
       
   466             j++;
       
   467         }
       
   468         /* Exit if v is smaller than both sons */
       
   469         if (smaller(tree, v, s->heap[j], s->depth)) break;
       
   470 
       
   471         /* Exchange v with the smallest son */
       
   472         s->heap[k] = s->heap[j];  k = j;
       
   473 
       
   474         /* And continue down the tree, setting j to the left son of k */
       
   475         j <<= 1;
       
   476     }
       
   477     s->heap[k] = v;
       
   478 }
       
   479 
       
   480 /* ===========================================================================
       
   481  * Compute the optimal bit lengths for a tree and update the total bit length
       
   482  * for the current block.
       
   483  * IN assertion: the fields freq and dad are set, heap[heap_max] and
       
   484  *    above are the tree nodes sorted by increasing frequency.
       
   485  * OUT assertions: the field len is set to the optimal bit length, the
       
   486  *     array bl_count contains the frequencies for each bit length.
       
   487  *     The length opt_len is updated; static_len is also updated if stree is
       
   488  *     not null.
       
   489  */
       
   490 local void gen_bitlen(s, desc)
       
   491     deflate_state *s;
       
   492     tree_desc *desc;    /* the tree descriptor */
       
   493 {
       
   494     ct_data *tree        = desc->dyn_tree;
       
   495     int max_code         = desc->max_code;
       
   496     const ct_data *stree = desc->stat_desc->static_tree;
       
   497     const intf *extra    = desc->stat_desc->extra_bits;
       
   498     int base             = desc->stat_desc->extra_base;
       
   499     int max_length       = desc->stat_desc->max_length;
       
   500     int h;              /* heap index */
       
   501     int n, m;           /* iterate over the tree elements */
       
   502     int bits;           /* bit length */
       
   503     int xbits;          /* extra bits */
       
   504     ush f;              /* frequency */
       
   505     int overflow = 0;   /* number of elements with bit length too large */
       
   506 
       
   507     for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
       
   508 
       
   509     /* In a first pass, compute the optimal bit lengths (which may
       
   510      * overflow in the case of the bit length tree).
       
   511      */
       
   512     tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
       
   513 
       
   514     for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
       
   515         n = s->heap[h];
       
   516         bits = tree[tree[n].Dad].Len + 1;
       
   517         if (bits > max_length) bits = max_length, overflow++;
       
   518         tree[n].Len = (ush)bits;
       
   519         /* We overwrite tree[n].Dad which is no longer needed */
       
   520 
       
   521         if (n > max_code) continue; /* not a leaf node */
       
   522 
       
   523         s->bl_count[bits]++;
       
   524         xbits = 0;
       
   525         if (n >= base) xbits = extra[n-base];
       
   526         f = tree[n].Freq;
       
   527         s->opt_len += (ulg)f * (bits + xbits);
       
   528         if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
       
   529     }
       
   530     if (overflow == 0) return;
       
   531 
       
   532     Trace((stderr,"\nbit length overflow\n"));
       
   533     /* This happens for example on obj2 and pic of the Calgary corpus */
       
   534 
       
   535     /* Find the first bit length which could increase: */
       
   536     do {
       
   537         bits = max_length-1;
       
   538         while (s->bl_count[bits] == 0) bits--;
       
   539         s->bl_count[bits]--;      /* move one leaf down the tree */
       
   540         s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
       
   541         s->bl_count[max_length]--;
       
   542         /* The brother of the overflow item also moves one step up,
       
   543          * but this does not affect bl_count[max_length]
       
   544          */
       
   545         overflow -= 2;
       
   546     } while (overflow > 0);
       
   547 
       
   548     /* Now recompute all bit lengths, scanning in increasing frequency.
       
   549      * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
       
   550      * lengths instead of fixing only the wrong ones. This idea is taken
       
   551      * from 'ar' written by Haruhiko Okumura.)
       
   552      */
       
   553     for (bits = max_length; bits != 0; bits--) {
       
   554         n = s->bl_count[bits];
       
   555         while (n != 0) {
       
   556             m = s->heap[--h];
       
   557             if (m > max_code) continue;
       
   558             if ((unsigned) tree[m].Len != (unsigned) bits) {
       
   559                 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
       
   560                 s->opt_len += ((long)bits - (long)tree[m].Len)
       
   561                               *(long)tree[m].Freq;
       
   562                 tree[m].Len = (ush)bits;
       
   563             }
       
   564             n--;
       
   565         }
       
   566     }
       
   567 }
       
   568 
       
   569 /* ===========================================================================
       
   570  * Generate the codes for a given tree and bit counts (which need not be
       
   571  * optimal).
       
   572  * IN assertion: the array bl_count contains the bit length statistics for
       
   573  * the given tree and the field len is set for all tree elements.
       
   574  * OUT assertion: the field code is set for all tree elements of non
       
   575  *     zero code length.
       
   576  */
       
   577 local void gen_codes (tree, max_code, bl_count)
       
   578     ct_data *tree;             /* the tree to decorate */
       
   579     int max_code;              /* largest code with non zero frequency */
       
   580     ushf *bl_count;            /* number of codes at each bit length */
       
   581 {
       
   582     ush next_code[MAX_BITS+1]; /* next code value for each bit length */
       
   583     ush code = 0;              /* running code value */
       
   584     int bits;                  /* bit index */
       
   585     int n;                     /* code index */
       
   586 
       
   587     /* The distribution counts are first used to generate the code values
       
   588      * without bit reversal.
       
   589      */
       
   590     for (bits = 1; bits <= MAX_BITS; bits++) {
       
   591         next_code[bits] = code = (code + bl_count[bits-1]) << 1;
       
   592     }
       
   593     /* Check that the bit counts in bl_count are consistent. The last code
       
   594      * must be all ones.
       
   595      */
       
   596     Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
       
   597             "inconsistent bit counts");
       
   598     Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
       
   599 
       
   600     for (n = 0;  n <= max_code; n++) {
       
   601         int len = tree[n].Len;
       
   602         if (len == 0) continue;
       
   603         /* Now reverse the bits */
       
   604         tree[n].Code = bi_reverse(next_code[len]++, len);
       
   605 
       
   606         Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
       
   607              n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
       
   608     }
       
   609 }
       
   610 
       
   611 /* ===========================================================================
       
   612  * Construct one Huffman tree and assigns the code bit strings and lengths.
       
   613  * Update the total bit length for the current block.
       
   614  * IN assertion: the field freq is set for all tree elements.
       
   615  * OUT assertions: the fields len and code are set to the optimal bit length
       
   616  *     and corresponding code. The length opt_len is updated; static_len is
       
   617  *     also updated if stree is not null. The field max_code is set.
       
   618  */
       
   619 local void build_tree(s, desc)
       
   620     deflate_state *s;
       
   621     tree_desc *desc; /* the tree descriptor */
       
   622 {
       
   623     ct_data *tree         = desc->dyn_tree;
       
   624     const ct_data *stree  = desc->stat_desc->static_tree;
       
   625     int elems             = desc->stat_desc->elems;
       
   626     int n, m;          /* iterate over heap elements */
       
   627     int max_code = -1; /* largest code with non zero frequency */
       
   628     int node;          /* new node being created */
       
   629 
       
   630     /* Construct the initial heap, with least frequent element in
       
   631      * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
       
   632      * heap[0] is not used.
       
   633      */
       
   634     s->heap_len = 0, s->heap_max = HEAP_SIZE;
       
   635 
       
   636     for (n = 0; n < elems; n++) {
       
   637         if (tree[n].Freq != 0) {
       
   638             s->heap[++(s->heap_len)] = max_code = n;
       
   639             s->depth[n] = 0;
       
   640         } else {
       
   641             tree[n].Len = 0;
       
   642         }
       
   643     }
       
   644 
       
   645     /* The pkzip format requires that at least one distance code exists,
       
   646      * and that at least one bit should be sent even if there is only one
       
   647      * possible code. So to avoid special checks later on we force at least
       
   648      * two codes of non zero frequency.
       
   649      */
       
   650     while (s->heap_len < 2) {
       
   651         node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
       
   652         tree[node].Freq = 1;
       
   653         s->depth[node] = 0;
       
   654         s->opt_len--; if (stree) s->static_len -= stree[node].Len;
       
   655         /* node is 0 or 1 so it does not have extra bits */
       
   656     }
       
   657     desc->max_code = max_code;
       
   658 
       
   659     /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
       
   660      * establish sub-heaps of increasing lengths:
       
   661      */
       
   662     for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
       
   663 
       
   664     /* Construct the Huffman tree by repeatedly combining the least two
       
   665      * frequent nodes.
       
   666      */
       
   667     node = elems;              /* next internal node of the tree */
       
   668     do {
       
   669         pqremove(s, tree, n);  /* n = node of least frequency */
       
   670         m = s->heap[SMALLEST]; /* m = node of next least frequency */
       
   671 
       
   672         s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
       
   673         s->heap[--(s->heap_max)] = m;
       
   674 
       
   675         /* Create a new node father of n and m */
       
   676         tree[node].Freq = tree[n].Freq + tree[m].Freq;
       
   677         s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
       
   678                                 s->depth[n] : s->depth[m]) + 1);
       
   679         tree[n].Dad = tree[m].Dad = (ush)node;
       
   680 #ifdef DUMP_BL_TREE
       
   681         if (tree == s->bl_tree) {
       
   682             fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
       
   683                     node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
       
   684         }
       
   685 #endif
       
   686         /* and insert the new node in the heap */
       
   687         s->heap[SMALLEST] = node++;
       
   688         pqdownheap(s, tree, SMALLEST);
       
   689 
       
   690     } while (s->heap_len >= 2);
       
   691 
       
   692     s->heap[--(s->heap_max)] = s->heap[SMALLEST];
       
   693 
       
   694     /* At this point, the fields freq and dad are set. We can now
       
   695      * generate the bit lengths.
       
   696      */
       
   697     gen_bitlen(s, (tree_desc *)desc);
       
   698 
       
   699     /* The field len is now set, we can generate the bit codes */
       
   700     gen_codes ((ct_data *)tree, max_code, s->bl_count);
       
   701 }
       
   702 
       
   703 /* ===========================================================================
       
   704  * Scan a literal or distance tree to determine the frequencies of the codes
       
   705  * in the bit length tree.
       
   706  */
       
   707 local void scan_tree (s, tree, max_code)
       
   708     deflate_state *s;
       
   709     ct_data *tree;   /* the tree to be scanned */
       
   710     int max_code;    /* and its largest code of non zero frequency */
       
   711 {
       
   712     int n;                     /* iterates over all tree elements */
       
   713     int prevlen = -1;          /* last emitted length */
       
   714     int curlen;                /* length of current code */
       
   715     int nextlen = tree[0].Len; /* length of next code */
       
   716     int count = 0;             /* repeat count of the current code */
       
   717     int max_count = 7;         /* max repeat count */
       
   718     int min_count = 4;         /* min repeat count */
       
   719 
       
   720     if (nextlen == 0) max_count = 138, min_count = 3;
       
   721     tree[max_code+1].Len = (ush)0xffff; /* guard */
       
   722 
       
   723     for (n = 0; n <= max_code; n++) {
       
   724         curlen = nextlen; nextlen = tree[n+1].Len;
       
   725         if (++count < max_count && curlen == nextlen) {
       
   726             continue;
       
   727         } else if (count < min_count) {
       
   728             s->bl_tree[curlen].Freq += count;
       
   729         } else if (curlen != 0) {
       
   730             if (curlen != prevlen) s->bl_tree[curlen].Freq++;
       
   731             s->bl_tree[REP_3_6].Freq++;
       
   732         } else if (count <= 10) {
       
   733             s->bl_tree[REPZ_3_10].Freq++;
       
   734         } else {
       
   735             s->bl_tree[REPZ_11_138].Freq++;
       
   736         }
       
   737         count = 0; prevlen = curlen;
       
   738         if (nextlen == 0) {
       
   739             max_count = 138, min_count = 3;
       
   740         } else if (curlen == nextlen) {
       
   741             max_count = 6, min_count = 3;
       
   742         } else {
       
   743             max_count = 7, min_count = 4;
       
   744         }
       
   745     }
       
   746 }
       
   747 
       
   748 /* ===========================================================================
       
   749  * Send a literal or distance tree in compressed form, using the codes in
       
   750  * bl_tree.
       
   751  */
       
   752 local void send_tree (s, tree, max_code)
       
   753     deflate_state *s;
       
   754     ct_data *tree; /* the tree to be scanned */
       
   755     int max_code;       /* and its largest code of non zero frequency */
       
   756 {
       
   757     int n;                     /* iterates over all tree elements */
       
   758     int prevlen = -1;          /* last emitted length */
       
   759     int curlen;                /* length of current code */
       
   760     int nextlen = tree[0].Len; /* length of next code */
       
   761     int count = 0;             /* repeat count of the current code */
       
   762     int max_count = 7;         /* max repeat count */
       
   763     int min_count = 4;         /* min repeat count */
       
   764 
       
   765     /* tree[max_code+1].Len = -1; */  /* guard already set */
       
   766     if (nextlen == 0) max_count = 138, min_count = 3;
       
   767 
       
   768     for (n = 0; n <= max_code; n++) {
       
   769         curlen = nextlen; nextlen = tree[n+1].Len;
       
   770         if (++count < max_count && curlen == nextlen) {
       
   771             continue;
       
   772         } else if (count < min_count) {
       
   773             do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
       
   774 
       
   775         } else if (curlen != 0) {
       
   776             if (curlen != prevlen) {
       
   777                 send_code(s, curlen, s->bl_tree); count--;
       
   778             }
       
   779             Assert(count >= 3 && count <= 6, " 3_6?");
       
   780             send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
       
   781 
       
   782         } else if (count <= 10) {
       
   783             send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
       
   784 
       
   785         } else {
       
   786             send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
       
   787         }
       
   788         count = 0; prevlen = curlen;
       
   789         if (nextlen == 0) {
       
   790             max_count = 138, min_count = 3;
       
   791         } else if (curlen == nextlen) {
       
   792             max_count = 6, min_count = 3;
       
   793         } else {
       
   794             max_count = 7, min_count = 4;
       
   795         }
       
   796     }
       
   797 }
       
   798 
       
   799 /* ===========================================================================
       
   800  * Construct the Huffman tree for the bit lengths and return the index in
       
   801  * bl_order of the last bit length code to send.
       
   802  */
       
   803 local int build_bl_tree(s)
       
   804     deflate_state *s;
       
   805 {
       
   806     int max_blindex;  /* index of last bit length code of non zero freq */
       
   807 
       
   808     /* Determine the bit length frequencies for literal and distance trees */
       
   809     scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
       
   810     scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
       
   811 
       
   812     /* Build the bit length tree: */
       
   813     build_tree(s, (tree_desc *)(&(s->bl_desc)));
       
   814     /* opt_len now includes the length of the tree representations, except
       
   815      * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
       
   816      */
       
   817 
       
   818     /* Determine the number of bit length codes to send. The pkzip format
       
   819      * requires that at least 4 bit length codes be sent. (appnote.txt says
       
   820      * 3 but the actual value used is 4.)
       
   821      */
       
   822     for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
       
   823         if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
       
   824     }
       
   825     /* Update opt_len to include the bit length tree and counts */
       
   826     s->opt_len += 3*(max_blindex+1) + 5+5+4;
       
   827     Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
       
   828             s->opt_len, s->static_len));
       
   829 
       
   830     return max_blindex;
       
   831 }
       
   832 
       
   833 /* ===========================================================================
       
   834  * Send the header for a block using dynamic Huffman trees: the counts, the
       
   835  * lengths of the bit length codes, the literal tree and the distance tree.
       
   836  * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
       
   837  */
       
   838 local void send_all_trees(s, lcodes, dcodes, blcodes)
       
   839     deflate_state *s;
       
   840     int lcodes, dcodes, blcodes; /* number of codes for each tree */
       
   841 {
       
   842     int rank;                    /* index in bl_order */
       
   843 
       
   844     Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
       
   845     Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
       
   846             "too many codes");
       
   847     Tracev((stderr, "\nbl counts: "));
       
   848     send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
       
   849     send_bits(s, dcodes-1,   5);
       
   850     send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
       
   851     for (rank = 0; rank < blcodes; rank++) {
       
   852         Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
       
   853         send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
       
   854     }
       
   855     Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
       
   856 
       
   857     send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
       
   858     Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
       
   859 
       
   860     send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
       
   861     Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
       
   862 }
       
   863 
       
   864 /* ===========================================================================
       
   865  * Send a stored block
       
   866  */
       
   867 void _tr_stored_block(s, buf, stored_len, eof)
       
   868     deflate_state *s;
       
   869     charf *buf;       /* input block */
       
   870     ulg stored_len;   /* length of input block */
       
   871     int eof;          /* true if this is the last block for a file */
       
   872 {
       
   873     send_bits(s, (STORED_BLOCK<<1)+eof, 3);  /* send block type */
       
   874 #ifdef DEBUG
       
   875     s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
       
   876     s->compressed_len += (stored_len + 4) << 3;
       
   877 #endif
       
   878     copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
       
   879 }
       
   880 
       
   881 /* ===========================================================================
       
   882  * Send one empty static block to give enough lookahead for inflate.
       
   883  * This takes 10 bits, of which 7 may remain in the bit buffer.
       
   884  * The current inflate code requires 9 bits of lookahead. If the
       
   885  * last two codes for the previous block (real code plus EOB) were coded
       
   886  * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
       
   887  * the last real code. In this case we send two empty static blocks instead
       
   888  * of one. (There are no problems if the previous block is stored or fixed.)
       
   889  * To simplify the code, we assume the worst case of last real code encoded
       
   890  * on one bit only.
       
   891  */
       
   892 void _tr_align(s)
       
   893     deflate_state *s;
       
   894 {
       
   895     send_bits(s, STATIC_TREES<<1, 3);
       
   896     send_code(s, END_BLOCK, static_ltree);
       
   897 #ifdef DEBUG
       
   898     s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
       
   899 #endif
       
   900     bi_flush(s);
       
   901     /* Of the 10 bits for the empty block, we have already sent
       
   902      * (10 - bi_valid) bits. The lookahead for the last real code (before
       
   903      * the EOB of the previous block) was thus at least one plus the length
       
   904      * of the EOB plus what we have just sent of the empty static block.
       
   905      */
       
   906     if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
       
   907         send_bits(s, STATIC_TREES<<1, 3);
       
   908         send_code(s, END_BLOCK, static_ltree);
       
   909 #ifdef DEBUG
       
   910         s->compressed_len += 10L;
       
   911 #endif
       
   912         bi_flush(s);
       
   913     }
       
   914     s->last_eob_len = 7;
       
   915 }
       
   916 
       
   917 /* ===========================================================================
       
   918  * Determine the best encoding for the current block: dynamic trees, static
       
   919  * trees or store, and output the encoded block to the zip file.
       
   920  */
       
   921 void _tr_flush_block(s, buf, stored_len, eof)
       
   922     deflate_state *s;
       
   923     charf *buf;       /* input block, or NULL if too old */
       
   924     ulg stored_len;   /* length of input block */
       
   925     int eof;          /* true if this is the last block for a file */
       
   926 {
       
   927     ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
       
   928     int max_blindex = 0;  /* index of last bit length code of non zero freq */
       
   929 
       
   930     /* Build the Huffman trees unless a stored block is forced */
       
   931     if (s->level > 0) {
       
   932 
       
   933         /* Check if the file is binary or text */
       
   934         if (stored_len > 0 && s->strm->data_type == Z_UNKNOWN)
       
   935             set_data_type(s);
       
   936 
       
   937         /* Construct the literal and distance trees */
       
   938         build_tree(s, (tree_desc *)(&(s->l_desc)));
       
   939         Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
       
   940                 s->static_len));
       
   941 
       
   942         build_tree(s, (tree_desc *)(&(s->d_desc)));
       
   943         Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
       
   944                 s->static_len));
       
   945         /* At this point, opt_len and static_len are the total bit lengths of
       
   946          * the compressed block data, excluding the tree representations.
       
   947          */
       
   948 
       
   949         /* Build the bit length tree for the above two trees, and get the index
       
   950          * in bl_order of the last bit length code to send.
       
   951          */
       
   952         max_blindex = build_bl_tree(s);
       
   953 
       
   954         /* Determine the best encoding. Compute the block lengths in bytes. */
       
   955         opt_lenb = (s->opt_len+3+7)>>3;
       
   956         static_lenb = (s->static_len+3+7)>>3;
       
   957 
       
   958         Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
       
   959                 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
       
   960                 s->last_lit));
       
   961 
       
   962         if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
       
   963 
       
   964     } else {
       
   965         Assert(buf != (char*)0, "lost buf");
       
   966         opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
       
   967     }
       
   968 
       
   969 #ifdef FORCE_STORED
       
   970     if (buf != (char*)0) { /* force stored block */
       
   971 #else
       
   972     if (stored_len+4 <= opt_lenb && buf != (char*)0) {
       
   973                        /* 4: two words for the lengths */
       
   974 #endif
       
   975         /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
       
   976          * Otherwise we can't have processed more than WSIZE input bytes since
       
   977          * the last block flush, because compression would have been
       
   978          * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
       
   979          * transform a block into a stored block.
       
   980          */
       
   981         _tr_stored_block(s, buf, stored_len, eof);
       
   982 
       
   983 #ifdef FORCE_STATIC
       
   984     } else if (static_lenb >= 0) { /* force static trees */
       
   985 #else
       
   986     } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
       
   987 #endif
       
   988         send_bits(s, (STATIC_TREES<<1)+eof, 3);
       
   989         compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
       
   990 #ifdef DEBUG
       
   991         s->compressed_len += 3 + s->static_len;
       
   992 #endif
       
   993     } else {
       
   994         send_bits(s, (DYN_TREES<<1)+eof, 3);
       
   995         send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
       
   996                        max_blindex+1);
       
   997         compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
       
   998 #ifdef DEBUG
       
   999         s->compressed_len += 3 + s->opt_len;
       
  1000 #endif
       
  1001     }
       
  1002     Assert (s->compressed_len == s->bits_sent, "bad compressed size");
       
  1003     /* The above check is made mod 2^32, for files larger than 512 MB
       
  1004      * and uLong implemented on 32 bits.
       
  1005      */
       
  1006     init_block(s);
       
  1007 
       
  1008     if (eof) {
       
  1009         bi_windup(s);
       
  1010 #ifdef DEBUG
       
  1011         s->compressed_len += 7;  /* align on byte boundary */
       
  1012 #endif
       
  1013     }
       
  1014     Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
       
  1015            s->compressed_len-7*eof));
       
  1016 }
       
  1017 
       
  1018 /* ===========================================================================
       
  1019  * Save the match info and tally the frequency counts. Return true if
       
  1020  * the current block must be flushed.
       
  1021  */
       
  1022 int _tr_tally (s, dist, lc)
       
  1023     deflate_state *s;
       
  1024     unsigned dist;  /* distance of matched string */
       
  1025     unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
       
  1026 {
       
  1027     s->d_buf[s->last_lit] = (ush)dist;
       
  1028     s->l_buf[s->last_lit++] = (uch)lc;
       
  1029     if (dist == 0) {
       
  1030         /* lc is the unmatched char */
       
  1031         s->dyn_ltree[lc].Freq++;
       
  1032     } else {
       
  1033         s->matches++;
       
  1034         /* Here, lc is the match length - MIN_MATCH */
       
  1035         dist--;             /* dist = match distance - 1 */
       
  1036         Assert((ush)dist < (ush)MAX_DIST(s) &&
       
  1037                (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
       
  1038                (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
       
  1039 
       
  1040         s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
       
  1041         s->dyn_dtree[d_code(dist)].Freq++;
       
  1042     }
       
  1043 
       
  1044 #ifdef TRUNCATE_BLOCK
       
  1045     /* Try to guess if it is profitable to stop the current block here */
       
  1046     if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
       
  1047         /* Compute an upper bound for the compressed length */
       
  1048         ulg out_length = (ulg)s->last_lit*8L;
       
  1049         ulg in_length = (ulg)((long)s->strstart - s->block_start);
       
  1050         int dcode;
       
  1051         for (dcode = 0; dcode < D_CODES; dcode++) {
       
  1052             out_length += (ulg)s->dyn_dtree[dcode].Freq *
       
  1053                 (5L+extra_dbits[dcode]);
       
  1054         }
       
  1055         out_length >>= 3;
       
  1056         Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
       
  1057                s->last_lit, in_length, out_length,
       
  1058                100L - out_length*100L/in_length));
       
  1059         if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
       
  1060     }
       
  1061 #endif
       
  1062     return (s->last_lit == s->lit_bufsize-1);
       
  1063     /* We avoid equality with lit_bufsize because of wraparound at 64K
       
  1064      * on 16 bit machines and because stored blocks are restricted to
       
  1065      * 64K-1 bytes.
       
  1066      */
       
  1067 }
       
  1068 
       
  1069 /* ===========================================================================
       
  1070  * Send the block data compressed using the given Huffman trees
       
  1071  */
       
  1072 local void compress_block(s, ltree, dtree)
       
  1073     deflate_state *s;
       
  1074     ct_data *ltree; /* literal tree */
       
  1075     ct_data *dtree; /* distance tree */
       
  1076 {
       
  1077     unsigned dist;      /* distance of matched string */
       
  1078     int lc;             /* match length or unmatched char (if dist == 0) */
       
  1079     unsigned lx = 0;    /* running index in l_buf */
       
  1080     unsigned code;      /* the code to send */
       
  1081     int extra;          /* number of extra bits to send */
       
  1082 
       
  1083     if (s->last_lit != 0) do {
       
  1084         dist = s->d_buf[lx];
       
  1085         lc = s->l_buf[lx++];
       
  1086         if (dist == 0) {
       
  1087             send_code(s, lc, ltree); /* send a literal byte */
       
  1088             Tracecv(isgraph(lc), (stderr," '%c' ", lc));
       
  1089         } else {
       
  1090             /* Here, lc is the match length - MIN_MATCH */
       
  1091             code = _length_code[lc];
       
  1092             send_code(s, code+LITERALS+1, ltree); /* send the length code */
       
  1093             extra = extra_lbits[code];
       
  1094             if (extra != 0) {
       
  1095                 lc -= base_length[code];
       
  1096                 send_bits(s, lc, extra);       /* send the extra length bits */
       
  1097             }
       
  1098             dist--; /* dist is now the match distance - 1 */
       
  1099             code = d_code(dist);
       
  1100             Assert (code < D_CODES, "bad d_code");
       
  1101 
       
  1102             send_code(s, code, dtree);       /* send the distance code */
       
  1103             extra = extra_dbits[code];
       
  1104             if (extra != 0) {
       
  1105                 dist -= base_dist[code];
       
  1106                 send_bits(s, dist, extra);   /* send the extra distance bits */
       
  1107             }
       
  1108         } /* literal or match pair ? */
       
  1109 
       
  1110         /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
       
  1111         Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
       
  1112                "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 BINARY or TEXT, using a crude approximation:
       
  1122  * set it to Z_TEXT if all symbols are either printable characters (33 to 255)
       
  1123  * or white spaces (9 to 13, or 32); or set it to Z_BINARY otherwise.
       
  1124  * IN assertion: the fields Freq of dyn_ltree are set.
       
  1125  */
       
  1126 local void set_data_type(s)
       
  1127     deflate_state *s;
       
  1128 {
       
  1129     int n;
       
  1130 
       
  1131     for (n = 0; n < 9; n++)
       
  1132         if (s->dyn_ltree[n].Freq != 0)
       
  1133             break;
       
  1134     if (n == 9)
       
  1135         for (n = 14; n < 32; n++)
       
  1136             if (s->dyn_ltree[n].Freq != 0)
       
  1137                 break;
       
  1138     s->strm->data_type = (n == 32) ? Z_TEXT : Z_BINARY;
       
  1139 }
       
  1140 
       
  1141 /* ===========================================================================
       
  1142  * Reverse the first len bits of a code, using straightforward code (a faster
       
  1143  * method would use a table)
       
  1144  * IN assertion: 1 <= len <= 15
       
  1145  */
       
  1146 local unsigned bi_reverse(code, len)
       
  1147     unsigned code; /* the value to invert */
       
  1148     int len;       /* its bit length */
       
  1149 {
       
  1150     register unsigned res = 0;
       
  1151     do {
       
  1152         res |= code & 1;
       
  1153         code >>= 1, res <<= 1;
       
  1154     } while (--len > 0);
       
  1155     return res >> 1;
       
  1156 }
       
  1157 
       
  1158 /* ===========================================================================
       
  1159  * Flush the bit buffer, keeping at most 7 bits in it.
       
  1160  */
       
  1161 local void bi_flush(s)
       
  1162     deflate_state *s;
       
  1163 {
       
  1164     if (s->bi_valid == 16) {
       
  1165         put_short(s, s->bi_buf);
       
  1166         s->bi_buf = 0;
       
  1167         s->bi_valid = 0;
       
  1168     } else if (s->bi_valid >= 8) {
       
  1169         put_byte(s, (Byte)s->bi_buf);
       
  1170         s->bi_buf >>= 8;
       
  1171         s->bi_valid -= 8;
       
  1172     }
       
  1173 }
       
  1174 
       
  1175 /* ===========================================================================
       
  1176  * Flush the bit buffer and align the output on a byte boundary
       
  1177  */
       
  1178 local void bi_windup(s)
       
  1179     deflate_state *s;
       
  1180 {
       
  1181     if (s->bi_valid > 8) {
       
  1182         put_short(s, s->bi_buf);
       
  1183     } else if (s->bi_valid > 0) {
       
  1184         put_byte(s, (Byte)s->bi_buf);
       
  1185     }
       
  1186     s->bi_buf = 0;
       
  1187     s->bi_valid = 0;
       
  1188 #ifdef DEBUG
       
  1189     s->bits_sent = (s->bits_sent+7) & ~7;
       
  1190 #endif
       
  1191 }
       
  1192 
       
  1193 /* ===========================================================================
       
  1194  * Copy a stored block, storing first the length and its
       
  1195  * one's complement if requested.
       
  1196  */
       
  1197 local void copy_block(s, buf, len, header)
       
  1198     deflate_state *s;
       
  1199     charf    *buf;    /* the input data */
       
  1200     unsigned len;     /* its length */
       
  1201     int      header;  /* true if block header must be written */
       
  1202 {
       
  1203     bi_windup(s);        /* align on byte boundary */
       
  1204     s->last_eob_len = 8; /* enough lookahead for inflate */
       
  1205 
       
  1206     if (header) {
       
  1207         put_short(s, (ush)len);
       
  1208         put_short(s, (ush)~len);
       
  1209 #ifdef DEBUG
       
  1210         s->bits_sent += 2*16;
       
  1211 #endif
       
  1212     }
       
  1213 #ifdef DEBUG
       
  1214     s->bits_sent += (ulg)len<<3;
       
  1215 #endif
       
  1216     while (len--) {
       
  1217         put_byte(s, *buf++);
       
  1218     }
       
  1219 }