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  1. /* trees.c -- output deflated data using Huffman coding
  2.  * Copyright (C) 1995-2012 Jean-loup Gailly
  3.  * detect_data_type() function provided freely by Cosmin Truta, 2006
  4.  * For conditions of distribution and use, see copyright notice in zlib.h
  5.  */
  6.  
  7. /*
  8.  *  ALGORITHM
  9.  *
  10.  *      The "deflation" process uses several Huffman trees. The more
  11.  *      common source values are represented by shorter bit sequences.
  12.  *
  13.  *      Each code tree is stored in a compressed form which is itself
  14.  * a Huffman encoding of the lengths of all the code strings (in
  15.  * ascending order by source values).  The actual code strings are
  16.  * reconstructed from the lengths in the inflate process, as described
  17.  * in the deflate specification.
  18.  *
  19.  *  REFERENCES
  20.  *
  21.  *      Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
  22.  *      Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
  23.  *
  24.  *      Storer, James A.
  25.  *          Data Compression:  Methods and Theory, pp. 49-50.
  26.  *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
  27.  *
  28.  *      Sedgewick, R.
  29.  *          Algorithms, p290.
  30.  *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
  31.  */
  32.  
  33. /* @(#) $Id$ */
  34.  
  35. /* #define GEN_TREES_H */
  36.  
  37. #include "deflate.h"
  38.  
  39. #ifdef DEBUG
  40. #  include <ctype.h>
  41. #endif
  42.  
  43. /* ===========================================================================
  44.  * Constants
  45.  */
  46.  
  47. #define MAX_BL_BITS 7
  48. /* Bit length codes must not exceed MAX_BL_BITS bits */
  49.  
  50. #define END_BLOCK 256
  51. /* end of block literal code */
  52.  
  53. #define REP_3_6      16
  54. /* repeat previous bit length 3-6 times (2 bits of repeat count) */
  55.  
  56. #define REPZ_3_10    17
  57. /* repeat a zero length 3-10 times  (3 bits of repeat count) */
  58.  
  59. #define REPZ_11_138  18
  60. /* repeat a zero length 11-138 times  (7 bits of repeat count) */
  61.  
  62. local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
  63.    = {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};
  64.  
  65. local const int extra_dbits[D_CODES] /* extra bits for each distance code */
  66.    = {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};
  67.  
  68. local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
  69.    = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
  70.  
  71. local const uch bl_order[BL_CODES]
  72.    = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
  73. /* The lengths of the bit length codes are sent in order of decreasing
  74.  * probability, to avoid transmitting the lengths for unused bit length codes.
  75.  */
  76.  
  77. /* ===========================================================================
  78.  * Local data. These are initialized only once.
  79.  */
  80.  
  81. #define DIST_CODE_LEN  512 /* see definition of array dist_code below */
  82.  
  83. #if defined(GEN_TREES_H) || !defined(STDC)
  84. /* non ANSI compilers may not accept trees.h */
  85.  
  86. local ct_data static_ltree[L_CODES+2];
  87. /* The static literal tree. Since the bit lengths are imposed, there is no
  88.  * need for the L_CODES extra codes used during heap construction. However
  89.  * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
  90.  * below).
  91.  */
  92.  
  93. local ct_data static_dtree[D_CODES];
  94. /* The static distance tree. (Actually a trivial tree since all codes use
  95.  * 5 bits.)
  96.  */
  97.  
  98. uch _dist_code[DIST_CODE_LEN];
  99. /* Distance codes. The first 256 values correspond to the distances
  100.  * 3 .. 258, the last 256 values correspond to the top 8 bits of
  101.  * the 15 bit distances.
  102.  */
  103.  
  104. uch _length_code[MAX_MATCH-MIN_MATCH+1];
  105. /* length code for each normalized match length (0 == MIN_MATCH) */
  106.  
  107. local int base_length[LENGTH_CODES];
  108. /* First normalized length for each code (0 = MIN_MATCH) */
  109.  
  110. local int base_dist[D_CODES];
  111. /* First normalized distance for each code (0 = distance of 1) */
  112.  
  113. #else
  114. #  include "trees.h"
  115. #endif /* GEN_TREES_H */
  116.  
  117. struct static_tree_desc_s {
  118.     const ct_data *static_tree;  /* static tree or NULL */
  119.     const intf *extra_bits;      /* extra bits for each code or NULL */
  120.     int     extra_base;          /* base index for extra_bits */
  121.     int     elems;               /* max number of elements in the tree */
  122.     int     max_length;          /* max bit length for the codes */
  123. };
  124.  
  125. local static_tree_desc  static_l_desc =
  126. {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
  127.  
  128. local static_tree_desc  static_d_desc =
  129. {static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};
  130.  
  131. local static_tree_desc  static_bl_desc =
  132. {(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
  133.  
  134. /* ===========================================================================
  135.  * Local (static) routines in this file.
  136.  */
  137.  
  138. local void tr_static_init OF((void));
  139. local void init_block     OF((deflate_state *s));
  140. local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));
  141. local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));
  142. local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));
  143. local void build_tree     OF((deflate_state *s, tree_desc *desc));
  144. local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));
  145. local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));
  146. local int  build_bl_tree  OF((deflate_state *s));
  147. local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
  148.                               int blcodes));
  149. local void compress_block OF((deflate_state *s, const ct_data *ltree,
  150.                               const ct_data *dtree));
  151. local int  detect_data_type OF((deflate_state *s));
  152. local unsigned bi_reverse OF((unsigned value, int length));
  153. local void bi_windup      OF((deflate_state *s));
  154. local void bi_flush       OF((deflate_state *s));
  155. local void copy_block     OF((deflate_state *s, charf *buf, unsigned len,
  156.                               int header));
  157.  
  158. #ifdef GEN_TREES_H
  159. local void gen_trees_header OF((void));
  160. #endif
  161.  
  162. #ifndef DEBUG
  163. #  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
  164.    /* Send a code of the given tree. c and tree must not have side effects */
  165.  
  166. #else /* DEBUG */
  167. #  define send_code(s, c, tree) \
  168.      { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
  169.        send_bits(s, tree[c].Code, tree[c].Len); }
  170. #endif
  171.  
  172. /* ===========================================================================
  173.  * Output a short LSB first on the stream.
  174.  * IN assertion: there is enough room in pendingBuf.
  175.  */
  176. #define put_short(s, w) { \
  177.     put_byte(s, (uch)((w) & 0xff)); \
  178.     put_byte(s, (uch)((ush)(w) >> 8)); \
  179. }
  180.  
  181. /* ===========================================================================
  182.  * Send a value on a given number of bits.
  183.  * IN assertion: length <= 16 and value fits in length bits.
  184.  */
  185. #ifdef DEBUG
  186. local void send_bits      OF((deflate_state *s, int value, int length));
  187.  
  188. local void send_bits(s, value, length)
  189.     deflate_state *s;
  190.     int value;  /* value to send */
  191.     int length; /* number of bits */
  192. {
  193.     Tracevv((stderr," l %2d v %4x ", length, value));
  194.     Assert(length > 0 && length <= 15, "invalid length");
  195.     s->bits_sent += (ulg)length;
  196.  
  197.     /* If not enough room in bi_buf, use (valid) bits from bi_buf and
  198.      * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
  199.      * unused bits in value.
  200.      */
  201.     if (s->bi_valid > (int)Buf_size - length) {
  202.         s->bi_buf |= (ush)value << s->bi_valid;
  203.         put_short(s, s->bi_buf);
  204.         s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
  205.         s->bi_valid += length - Buf_size;
  206.     } else {
  207.         s->bi_buf |= (ush)value << s->bi_valid;
  208.         s->bi_valid += length;
  209.     }
  210. }
  211. #else /* !DEBUG */
  212.  
  213. #define send_bits(s, value, length) \
  214. { int len = length;\
  215.   if (s->bi_valid > (int)Buf_size - len) {\
  216.     int val = value;\
  217.     s->bi_buf |= (ush)val << s->bi_valid;\
  218.     put_short(s, s->bi_buf);\
  219.     s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
  220.     s->bi_valid += len - Buf_size;\
  221.   } else {\
  222.     s->bi_buf |= (ush)(value) << s->bi_valid;\
  223.     s->bi_valid += len;\
  224.   }\
  225. }
  226. #endif /* DEBUG */
  227.  
  228.  
  229. /* the arguments must not have side effects */
  230.  
  231. /* ===========================================================================
  232.  * Initialize the various 'constant' tables.
  233.  */
  234. local void tr_static_init()
  235. {
  236. #if defined(GEN_TREES_H) || !defined(STDC)
  237.     static int static_init_done = 0;
  238.     int n;        /* iterates over tree elements */
  239.     int bits;     /* bit counter */
  240.     int length;   /* length value */
  241.     int code;     /* code value */
  242.     int dist;     /* distance index */
  243.     ush bl_count[MAX_BITS+1];
  244.     /* number of codes at each bit length for an optimal tree */
  245.  
  246.     if (static_init_done) return;
  247.  
  248.     /* For some embedded targets, global variables are not initialized: */
  249. #ifdef NO_INIT_GLOBAL_POINTERS
  250.     static_l_desc.static_tree = static_ltree;
  251.     static_l_desc.extra_bits = extra_lbits;
  252.     static_d_desc.static_tree = static_dtree;
  253.     static_d_desc.extra_bits = extra_dbits;
  254.     static_bl_desc.extra_bits = extra_blbits;
  255. #endif
  256.  
  257.     /* Initialize the mapping length (0..255) -> length code (0..28) */
  258.     length = 0;
  259.     for (code = 0; code < LENGTH_CODES-1; code++) {
  260.         base_length[code] = length;
  261.         for (n = 0; n < (1<<extra_lbits[code]); n++) {
  262.             _length_code[length++] = (uch)code;
  263.         }
  264.     }
  265.     Assert (length == 256, "tr_static_init: length != 256");
  266.     /* Note that the length 255 (match length 258) can be represented
  267.      * in two different ways: code 284 + 5 bits or code 285, so we
  268.      * overwrite length_code[255] to use the best encoding:
  269.      */
  270.     _length_code[length-1] = (uch)code;
  271.  
  272.     /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
  273.     dist = 0;
  274.     for (code = 0 ; code < 16; code++) {
  275.         base_dist[code] = dist;
  276.         for (n = 0; n < (1<<extra_dbits[code]); n++) {
  277.             _dist_code[dist++] = (uch)code;
  278.         }
  279.     }
  280.     Assert (dist == 256, "tr_static_init: dist != 256");
  281.     dist >>= 7; /* from now on, all distances are divided by 128 */
  282.     for ( ; code < D_CODES; code++) {
  283.         base_dist[code] = dist << 7;
  284.         for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
  285.             _dist_code[256 + dist++] = (uch)code;
  286.         }
  287.     }
  288.     Assert (dist == 256, "tr_static_init: 256+dist != 512");
  289.  
  290.     /* Construct the codes of the static literal tree */
  291.     for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
  292.     n = 0;
  293.     while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
  294.     while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
  295.     while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
  296.     while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
  297.     /* Codes 286 and 287 do not exist, but we must include them in the
  298.      * tree construction to get a canonical Huffman tree (longest code
  299.      * all ones)
  300.      */
  301.     gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
  302.  
  303.     /* The static distance tree is trivial: */
  304.     for (n = 0; n < D_CODES; n++) {
  305.         static_dtree[n].Len = 5;
  306.         static_dtree[n].Code = bi_reverse((unsigned)n, 5);
  307.     }
  308.     static_init_done = 1;
  309.  
  310. #  ifdef GEN_TREES_H
  311.     gen_trees_header();
  312. #  endif
  313. #endif /* defined(GEN_TREES_H) || !defined(STDC) */
  314. }
  315.  
  316. /* ===========================================================================
  317.  * Genererate the file trees.h describing the static trees.
  318.  */
  319. #ifdef GEN_TREES_H
  320. #  ifndef DEBUG
  321. #    include <stdio.h>
  322. #  endif
  323.  
  324. #  define SEPARATOR(i, last, width) \
  325.       ((i) == (last)? "\n};\n\n" :    \
  326.        ((i) % (width) == (width)-1 ? ",\n" : ", "))
  327.  
  328. void gen_trees_header()
  329. {
  330.     FILE *header = fopen("trees.h", "w");
  331.     int i;
  332.  
  333.     Assert (header != NULL, "Can't open trees.h");
  334.     fprintf(header,
  335.             "/* header created automatically with -DGEN_TREES_H */\n\n");
  336.  
  337.     fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
  338.     for (i = 0; i < L_CODES+2; i++) {
  339.         fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
  340.                 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
  341.     }
  342.  
  343.     fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
  344.     for (i = 0; i < D_CODES; i++) {
  345.         fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
  346.                 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
  347.     }
  348.  
  349.     fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
  350.     for (i = 0; i < DIST_CODE_LEN; i++) {
  351.         fprintf(header, "%2u%s", _dist_code[i],
  352.                 SEPARATOR(i, DIST_CODE_LEN-1, 20));
  353.     }
  354.  
  355.     fprintf(header,
  356.         "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
  357.     for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
  358.         fprintf(header, "%2u%s", _length_code[i],
  359.                 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
  360.     }
  361.  
  362.     fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
  363.     for (i = 0; i < LENGTH_CODES; i++) {
  364.         fprintf(header, "%1u%s", base_length[i],
  365.                 SEPARATOR(i, LENGTH_CODES-1, 20));
  366.     }
  367.  
  368.     fprintf(header, "local const int base_dist[D_CODES] = {\n");
  369.     for (i = 0; i < D_CODES; i++) {
  370.         fprintf(header, "%5u%s", base_dist[i],
  371.                 SEPARATOR(i, D_CODES-1, 10));
  372.     }
  373.  
  374.     fclose(header);
  375. }
  376. #endif /* GEN_TREES_H */
  377.  
  378. /* ===========================================================================
  379.  * Initialize the tree data structures for a new zlib stream.
  380.  */
  381. void ZLIB_INTERNAL _tr_init(s)
  382.     deflate_state *s;
  383. {
  384.     tr_static_init();
  385.  
  386.     s->l_desc.dyn_tree = s->dyn_ltree;
  387.     s->l_desc.stat_desc = &static_l_desc;
  388.  
  389.     s->d_desc.dyn_tree = s->dyn_dtree;
  390.     s->d_desc.stat_desc = &static_d_desc;
  391.  
  392.     s->bl_desc.dyn_tree = s->bl_tree;
  393.     s->bl_desc.stat_desc = &static_bl_desc;
  394.  
  395.     s->bi_buf = 0;
  396.     s->bi_valid = 0;
  397. #ifdef DEBUG
  398.     s->compressed_len = 0L;
  399.     s->bits_sent = 0L;
  400. #endif
  401.  
  402.     /* Initialize the first block of the first file: */
  403.     init_block(s);
  404. }
  405.  
  406. /* ===========================================================================
  407.  * Initialize a new block.
  408.  */
  409. local void init_block(s)
  410.     deflate_state *s;
  411. {
  412.     int n; /* iterates over tree elements */
  413.  
  414.     /* Initialize the trees. */
  415.     for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
  416.     for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
  417.     for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
  418.  
  419.     s->dyn_ltree[END_BLOCK].Freq = 1;
  420.     s->opt_len = s->static_len = 0L;
  421.     s->last_lit = s->matches = 0;
  422. }
  423.  
  424. #define SMALLEST 1
  425. /* Index within the heap array of least frequent node in the Huffman tree */
  426.  
  427.  
  428. /* ===========================================================================
  429.  * Remove the smallest element from the heap and recreate the heap with
  430.  * one less element. Updates heap and heap_len.
  431.  */
  432. #define pqremove(s, tree, top) \
  433. {\
  434.     top = s->heap[SMALLEST]; \
  435.     s->heap[SMALLEST] = s->heap[s->heap_len--]; \
  436.     pqdownheap(s, tree, SMALLEST); \
  437. }
  438.  
  439. /* ===========================================================================
  440.  * Compares to subtrees, using the tree depth as tie breaker when
  441.  * the subtrees have equal frequency. This minimizes the worst case length.
  442.  */
  443. #define smaller(tree, n, m, depth) \
  444.    (tree[n].Freq < tree[m].Freq || \
  445.    (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
  446.  
  447. /* ===========================================================================
  448.  * Restore the heap property by moving down the tree starting at node k,
  449.  * exchanging a node with the smallest of its two sons if necessary, stopping
  450.  * when the heap property is re-established (each father smaller than its
  451.  * two sons).
  452.  */
  453. local void pqdownheap(s, tree, k)
  454.     deflate_state *s;
  455.     ct_data *tree;  /* the tree to restore */
  456.     int k;               /* node to move down */
  457. {
  458.     int v = s->heap[k];
  459.     int j = k << 1;  /* left son of k */
  460.     while (j <= s->heap_len) {
  461.         /* Set j to the smallest of the two sons: */
  462.         if (j < s->heap_len &&
  463.             smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
  464.             j++;
  465.         }
  466.         /* Exit if v is smaller than both sons */
  467.         if (smaller(tree, v, s->heap[j], s->depth)) break;
  468.  
  469.         /* Exchange v with the smallest son */
  470.         s->heap[k] = s->heap[j];  k = j;
  471.  
  472.         /* And continue down the tree, setting j to the left son of k */
  473.         j <<= 1;
  474.     }
  475.     s->heap[k] = v;
  476. }
  477.  
  478. /* ===========================================================================
  479.  * Compute the optimal bit lengths for a tree and update the total bit length
  480.  * for the current block.
  481.  * IN assertion: the fields freq and dad are set, heap[heap_max] and
  482.  *    above are the tree nodes sorted by increasing frequency.
  483.  * OUT assertions: the field len is set to the optimal bit length, the
  484.  *     array bl_count contains the frequencies for each bit length.
  485.  *     The length opt_len is updated; static_len is also updated if stree is
  486.  *     not null.
  487.  */
  488. local void gen_bitlen(s, desc)
  489.     deflate_state *s;
  490.     tree_desc *desc;    /* the tree descriptor */
  491. {
  492.     ct_data *tree        = desc->dyn_tree;
  493.     int max_code         = desc->max_code;
  494.     const ct_data *stree = desc->stat_desc->static_tree;
  495.     const intf *extra    = desc->stat_desc->extra_bits;
  496.     int base             = desc->stat_desc->extra_base;
  497.     int max_length       = desc->stat_desc->max_length;
  498.     int h;              /* heap index */
  499.     int n, m;           /* iterate over the tree elements */
  500.     int bits;           /* bit length */
  501.     int xbits;          /* extra bits */
  502.     ush f;              /* frequency */
  503.     int overflow = 0;   /* number of elements with bit length too large */
  504.  
  505.     for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
  506.  
  507.     /* In a first pass, compute the optimal bit lengths (which may
  508.      * overflow in the case of the bit length tree).
  509.      */
  510.     tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
  511.  
  512.     for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
  513.         n = s->heap[h];
  514.         bits = tree[tree[n].Dad].Len + 1;
  515.         if (bits > max_length) bits = max_length, overflow++;
  516.         tree[n].Len = (ush)bits;
  517.         /* We overwrite tree[n].Dad which is no longer needed */
  518.  
  519.         if (n > max_code) continue; /* not a leaf node */
  520.  
  521.         s->bl_count[bits]++;
  522.         xbits = 0;
  523.         if (n >= base) xbits = extra[n-base];
  524.         f = tree[n].Freq;
  525.         s->opt_len += (ulg)f * (bits + xbits);
  526.         if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
  527.     }
  528.     if (overflow == 0) return;
  529.  
  530.     Trace((stderr,"\nbit length overflow\n"));
  531.     /* This happens for example on obj2 and pic of the Calgary corpus */
  532.  
  533.     /* Find the first bit length which could increase: */
  534.     do {
  535.         bits = max_length-1;
  536.         while (s->bl_count[bits] == 0) bits--;
  537.         s->bl_count[bits]--;      /* move one leaf down the tree */
  538.         s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
  539.         s->bl_count[max_length]--;
  540.         /* The brother of the overflow item also moves one step up,
  541.          * but this does not affect bl_count[max_length]
  542.          */
  543.         overflow -= 2;
  544.     } while (overflow > 0);
  545.  
  546.     /* Now recompute all bit lengths, scanning in increasing frequency.
  547.      * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
  548.      * lengths instead of fixing only the wrong ones. This idea is taken
  549.      * from 'ar' written by Haruhiko Okumura.)
  550.      */
  551.     for (bits = max_length; bits != 0; bits--) {
  552.         n = s->bl_count[bits];
  553.         while (n != 0) {
  554.             m = s->heap[--h];
  555.             if (m > max_code) continue;
  556.             if ((unsigned) tree[m].Len != (unsigned) bits) {
  557.                 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
  558.                 s->opt_len += ((long)bits - (long)tree[m].Len)
  559.                               *(long)tree[m].Freq;
  560.                 tree[m].Len = (ush)bits;
  561.             }
  562.             n--;
  563.         }
  564.     }
  565. }
  566.  
  567. /* ===========================================================================
  568.  * Generate the codes for a given tree and bit counts (which need not be
  569.  * optimal).
  570.  * IN assertion: the array bl_count contains the bit length statistics for
  571.  * the given tree and the field len is set for all tree elements.
  572.  * OUT assertion: the field code is set for all tree elements of non
  573.  *     zero code length.
  574.  */
  575. local void gen_codes (tree, max_code, bl_count)
  576.     ct_data *tree;             /* the tree to decorate */
  577.     int max_code;              /* largest code with non zero frequency */
  578.     ushf *bl_count;            /* number of codes at each bit length */
  579. {
  580.     ush next_code[MAX_BITS+1]; /* next code value for each bit length */
  581.     ush code = 0;              /* running code value */
  582.     int bits;                  /* bit index */
  583.     int n;                     /* code index */
  584.  
  585.     /* The distribution counts are first used to generate the code values
  586.      * without bit reversal.
  587.      */
  588.     for (bits = 1; bits <= MAX_BITS; bits++) {
  589.         next_code[bits] = code = (code + bl_count[bits-1]) << 1;
  590.     }
  591.     /* Check that the bit counts in bl_count are consistent. The last code
  592.      * must be all ones.
  593.      */
  594.     Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
  595.             "inconsistent bit counts");
  596.     Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
  597.  
  598.     for (n = 0;  n <= max_code; n++) {
  599.         int len = tree[n].Len;
  600.         if (len == 0) continue;
  601.         /* Now reverse the bits */
  602.         tree[n].Code = bi_reverse(next_code[len]++, len);
  603.  
  604.         Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
  605.              n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
  606.     }
  607. }
  608.  
  609. /* ===========================================================================
  610.  * Construct one Huffman tree and assigns the code bit strings and lengths.
  611.  * Update the total bit length for the current block.
  612.  * IN assertion: the field freq is set for all tree elements.
  613.  * OUT assertions: the fields len and code are set to the optimal bit length
  614.  *     and corresponding code. The length opt_len is updated; static_len is
  615.  *     also updated if stree is not null. The field max_code is set.
  616.  */
  617. local void build_tree(s, desc)
  618.     deflate_state *s;
  619.     tree_desc *desc; /* the tree descriptor */
  620. {
  621.     ct_data *tree         = desc->dyn_tree;
  622.     const ct_data *stree  = desc->stat_desc->static_tree;
  623.     int elems             = desc->stat_desc->elems;
  624.     int n, m;          /* iterate over heap elements */
  625.     int max_code = -1; /* largest code with non zero frequency */
  626.     int node;          /* new node being created */
  627.  
  628.     /* Construct the initial heap, with least frequent element in
  629.      * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
  630.      * heap[0] is not used.
  631.      */
  632.     s->heap_len = 0, s->heap_max = HEAP_SIZE;
  633.  
  634.     for (n = 0; n < elems; n++) {
  635.         if (tree[n].Freq != 0) {
  636.             s->heap[++(s->heap_len)] = max_code = n;
  637.             s->depth[n] = 0;
  638.         } else {
  639.             tree[n].Len = 0;
  640.         }
  641.     }
  642.  
  643.     /* The pkzip format requires that at least one distance code exists,
  644.      * and that at least one bit should be sent even if there is only one
  645.      * possible code. So to avoid special checks later on we force at least
  646.      * two codes of non zero frequency.
  647.      */
  648.     while (s->heap_len < 2) {
  649.         node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
  650.         tree[node].Freq = 1;
  651.         s->depth[node] = 0;
  652.         s->opt_len--; if (stree) s->static_len -= stree[node].Len;
  653.         /* node is 0 or 1 so it does not have extra bits */
  654.     }
  655.     desc->max_code = max_code;
  656.  
  657.     /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
  658.      * establish sub-heaps of increasing lengths:
  659.      */
  660.     for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
  661.  
  662.     /* Construct the Huffman tree by repeatedly combining the least two
  663.      * frequent nodes.
  664.      */
  665.     node = elems;              /* next internal node of the tree */
  666.     do {
  667.         pqremove(s, tree, n);  /* n = node of least frequency */
  668.         m = s->heap[SMALLEST]; /* m = node of next least frequency */
  669.  
  670.         s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
  671.         s->heap[--(s->heap_max)] = m;
  672.  
  673.         /* Create a new node father of n and m */
  674.         tree[node].Freq = tree[n].Freq + tree[m].Freq;
  675.         s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
  676.                                 s->depth[n] : s->depth[m]) + 1);
  677.         tree[n].Dad = tree[m].Dad = (ush)node;
  678. #ifdef DUMP_BL_TREE
  679.         if (tree == s->bl_tree) {
  680.             fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
  681.                     node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
  682.         }
  683. #endif
  684.         /* and insert the new node in the heap */
  685.         s->heap[SMALLEST] = node++;
  686.         pqdownheap(s, tree, SMALLEST);
  687.  
  688.     } while (s->heap_len >= 2);
  689.  
  690.     s->heap[--(s->heap_max)] = s->heap[SMALLEST];
  691.  
  692.     /* At this point, the fields freq and dad are set. We can now
  693.      * generate the bit lengths.
  694.      */
  695.     gen_bitlen(s, (tree_desc *)desc);
  696.  
  697.     /* The field len is now set, we can generate the bit codes */
  698.     gen_codes ((ct_data *)tree, max_code, s->bl_count);
  699. }
  700.  
  701. /* ===========================================================================
  702.  * Scan a literal or distance tree to determine the frequencies of the codes
  703.  * in the bit length tree.
  704.  */
  705. local void scan_tree (s, tree, max_code)
  706.     deflate_state *s;
  707.     ct_data *tree;   /* the tree to be scanned */
  708.     int max_code;    /* and its largest code of non zero frequency */
  709. {
  710.     int n;                     /* iterates over all tree elements */
  711.     int prevlen = -1;          /* last emitted length */
  712.     int curlen;                /* length of current code */
  713.     int nextlen = tree[0].Len; /* length of next code */
  714.     int count = 0;             /* repeat count of the current code */
  715.     int max_count = 7;         /* max repeat count */
  716.     int min_count = 4;         /* min repeat count */
  717.  
  718.     if (nextlen == 0) max_count = 138, min_count = 3;
  719.     tree[max_code+1].Len = (ush)0xffff; /* guard */
  720.  
  721.     for (n = 0; n <= max_code; n++) {
  722.         curlen = nextlen; nextlen = tree[n+1].Len;
  723.         if (++count < max_count && curlen == nextlen) {
  724.             continue;
  725.         } else if (count < min_count) {
  726.             s->bl_tree[curlen].Freq += count;
  727.         } else if (curlen != 0) {
  728.             if (curlen != prevlen) s->bl_tree[curlen].Freq++;
  729.             s->bl_tree[REP_3_6].Freq++;
  730.         } else if (count <= 10) {
  731.             s->bl_tree[REPZ_3_10].Freq++;
  732.         } else {
  733.             s->bl_tree[REPZ_11_138].Freq++;
  734.         }
  735.         count = 0; prevlen = curlen;
  736.         if (nextlen == 0) {
  737.             max_count = 138, min_count = 3;
  738.         } else if (curlen == nextlen) {
  739.             max_count = 6, min_count = 3;
  740.         } else {
  741.             max_count = 7, min_count = 4;
  742.         }
  743.     }
  744. }
  745.  
  746. /* ===========================================================================
  747.  * Send a literal or distance tree in compressed form, using the codes in
  748.  * bl_tree.
  749.  */
  750. local void send_tree (s, tree, max_code)
  751.     deflate_state *s;
  752.     ct_data *tree; /* the tree to be scanned */
  753.     int max_code;       /* and its largest code of non zero frequency */
  754. {
  755.     int n;                     /* iterates over all tree elements */
  756.     int prevlen = -1;          /* last emitted length */
  757.     int curlen;                /* length of current code */
  758.     int nextlen = tree[0].Len; /* length of next code */
  759.     int count = 0;             /* repeat count of the current code */
  760.     int max_count = 7;         /* max repeat count */
  761.     int min_count = 4;         /* min repeat count */
  762.  
  763.     /* tree[max_code+1].Len = -1; */  /* guard already set */
  764.     if (nextlen == 0) max_count = 138, min_count = 3;
  765.  
  766.     for (n = 0; n <= max_code; n++) {
  767.         curlen = nextlen; nextlen = tree[n+1].Len;
  768.         if (++count < max_count && curlen == nextlen) {
  769.             continue;
  770.         } else if (count < min_count) {
  771.             do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
  772.  
  773.         } else if (curlen != 0) {
  774.             if (curlen != prevlen) {
  775.                 send_code(s, curlen, s->bl_tree); count--;
  776.             }
  777.             Assert(count >= 3 && count <= 6, " 3_6?");
  778.             send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
  779.  
  780.         } else if (count <= 10) {
  781.             send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
  782.  
  783.         } else {
  784.             send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
  785.         }
  786.         count = 0; prevlen = curlen;
  787.         if (nextlen == 0) {
  788.             max_count = 138, min_count = 3;
  789.         } else if (curlen == nextlen) {
  790.             max_count = 6, min_count = 3;
  791.         } else {
  792.             max_count = 7, min_count = 4;
  793.         }
  794.     }
  795. }
  796.  
  797. /* ===========================================================================
  798.  * Construct the Huffman tree for the bit lengths and return the index in
  799.  * bl_order of the last bit length code to send.
  800.  */
  801. local int build_bl_tree(s)
  802.     deflate_state *s;
  803. {
  804.     int max_blindex;  /* index of last bit length code of non zero freq */
  805.  
  806.     /* Determine the bit length frequencies for literal and distance trees */
  807.     scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
  808.     scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
  809.  
  810.     /* Build the bit length tree: */
  811.     build_tree(s, (tree_desc *)(&(s->bl_desc)));
  812.     /* opt_len now includes the length of the tree representations, except
  813.      * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
  814.      */
  815.  
  816.     /* Determine the number of bit length codes to send. The pkzip format
  817.      * requires that at least 4 bit length codes be sent. (appnote.txt says
  818.      * 3 but the actual value used is 4.)
  819.      */
  820.     for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
  821.         if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
  822.     }
  823.     /* Update opt_len to include the bit length tree and counts */
  824.     s->opt_len += 3*(max_blindex+1) + 5+5+4;
  825.     Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
  826.             s->opt_len, s->static_len));
  827.  
  828.     return max_blindex;
  829. }
  830.  
  831. /* ===========================================================================
  832.  * Send the header for a block using dynamic Huffman trees: the counts, the
  833.  * lengths of the bit length codes, the literal tree and the distance tree.
  834.  * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
  835.  */
  836. local void send_all_trees(s, lcodes, dcodes, blcodes)
  837.     deflate_state *s;
  838.     int lcodes, dcodes, blcodes; /* number of codes for each tree */
  839. {
  840.     int rank;                    /* index in bl_order */
  841.  
  842.     Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
  843.     Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
  844.             "too many codes");
  845.     Tracev((stderr, "\nbl counts: "));
  846.     send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
  847.     send_bits(s, dcodes-1,   5);
  848.     send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
  849.     for (rank = 0; rank < blcodes; rank++) {
  850.         Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
  851.         send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
  852.     }
  853.     Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
  854.  
  855.     send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
  856.     Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
  857.  
  858.     send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
  859.     Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
  860. }
  861.  
  862. /* ===========================================================================
  863.  * Send a stored block
  864.  */
  865. void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
  866.     deflate_state *s;
  867.     charf *buf;       /* input block */
  868.     ulg stored_len;   /* length of input block */
  869.     int last;         /* one if this is the last block for a file */
  870. {
  871.     send_bits(s, (STORED_BLOCK<<1)+last, 3);    /* send block type */
  872. #ifdef DEBUG
  873.     s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
  874.     s->compressed_len += (stored_len + 4) << 3;
  875. #endif
  876.     copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
  877. }
  878.  
  879. /* ===========================================================================
  880.  * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
  881.  */
  882. void ZLIB_INTERNAL _tr_flush_bits(s)
  883.     deflate_state *s;
  884. {
  885.     bi_flush(s);
  886. }
  887.  
  888. /* ===========================================================================
  889.  * Send one empty static block to give enough lookahead for inflate.
  890.  * This takes 10 bits, of which 7 may remain in the bit buffer.
  891.  */
  892. void ZLIB_INTERNAL _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. }
  902.  
  903. /* ===========================================================================
  904.  * Determine the best encoding for the current block: dynamic trees, static
  905.  * trees or store, and output the encoded block to the zip file.
  906.  */
  907. void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
  908.     deflate_state *s;
  909.     charf *buf;       /* input block, or NULL if too old */
  910.     ulg stored_len;   /* length of input block */
  911.     int last;         /* one if this is the last block for a file */
  912. {
  913.     ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
  914.     int max_blindex = 0;  /* index of last bit length code of non zero freq */
  915.  
  916.     /* Build the Huffman trees unless a stored block is forced */
  917.     if (s->level > 0) {
  918.  
  919.         /* Check if the file is binary or text */
  920.         if (s->strm->data_type == Z_UNKNOWN)
  921.             s->strm->data_type = detect_data_type(s);
  922.  
  923.         /* Construct the literal and distance trees */
  924.         build_tree(s, (tree_desc *)(&(s->l_desc)));
  925.         Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
  926.                 s->static_len));
  927.  
  928.         build_tree(s, (tree_desc *)(&(s->d_desc)));
  929.         Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
  930.                 s->static_len));
  931.         /* At this point, opt_len and static_len are the total bit lengths of
  932.          * the compressed block data, excluding the tree representations.
  933.          */
  934.  
  935.         /* Build the bit length tree for the above two trees, and get the index
  936.          * in bl_order of the last bit length code to send.
  937.          */
  938.         max_blindex = build_bl_tree(s);
  939.  
  940.         /* Determine the best encoding. Compute the block lengths in bytes. */
  941.         opt_lenb = (s->opt_len+3+7)>>3;
  942.         static_lenb = (s->static_len+3+7)>>3;
  943.  
  944.         Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
  945.                 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
  946.                 s->last_lit));
  947.  
  948.         if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
  949.  
  950.     } else {
  951.         Assert(buf != (char*)0, "lost buf");
  952.         opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
  953.     }
  954.  
  955. #ifdef FORCE_STORED
  956.     if (buf != (char*)0) { /* force stored block */
  957. #else
  958.     if (stored_len+4 <= opt_lenb && buf != (char*)0) {
  959.                        /* 4: two words for the lengths */
  960. #endif
  961.         /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
  962.          * Otherwise we can't have processed more than WSIZE input bytes since
  963.          * the last block flush, because compression would have been
  964.          * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
  965.          * transform a block into a stored block.
  966.          */
  967.         _tr_stored_block(s, buf, stored_len, last);
  968.  
  969. #ifdef FORCE_STATIC
  970.     } else if (static_lenb >= 0) { /* force static trees */
  971. #else
  972.     } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
  973. #endif
  974.         send_bits(s, (STATIC_TREES<<1)+last, 3);
  975.         compress_block(s, (const ct_data *)static_ltree,
  976.                        (const ct_data *)static_dtree);
  977. #ifdef DEBUG
  978.         s->compressed_len += 3 + s->static_len;
  979. #endif
  980.     } else {
  981.         send_bits(s, (DYN_TREES<<1)+last, 3);
  982.         send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
  983.                        max_blindex+1);
  984.         compress_block(s, (const ct_data *)s->dyn_ltree,
  985.                        (const ct_data *)s->dyn_dtree);
  986. #ifdef DEBUG
  987.         s->compressed_len += 3 + s->opt_len;
  988. #endif
  989.     }
  990.     Assert (s->compressed_len == s->bits_sent, "bad compressed size");
  991.     /* The above check is made mod 2^32, for files larger than 512 MB
  992.      * and uLong implemented on 32 bits.
  993.      */
  994.     init_block(s);
  995.  
  996.     if (last) {
  997.         bi_windup(s);
  998. #ifdef DEBUG
  999.         s->compressed_len += 7;  /* align on byte boundary */
  1000. #endif
  1001.     }
  1002.     Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
  1003.            s->compressed_len-7*last));
  1004. }
  1005.  
  1006. /* ===========================================================================
  1007.  * Save the match info and tally the frequency counts. Return true if
  1008.  * the current block must be flushed.
  1009.  */
  1010. int ZLIB_INTERNAL _tr_tally (s, dist, lc)
  1011.     deflate_state *s;
  1012.     unsigned dist;  /* distance of matched string */
  1013.     unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
  1014. {
  1015.     s->d_buf[s->last_lit] = (ush)dist;
  1016.     s->l_buf[s->last_lit++] = (uch)lc;
  1017.     if (dist == 0) {
  1018.         /* lc is the unmatched char */
  1019.         s->dyn_ltree[lc].Freq++;
  1020.     } else {
  1021.         s->matches++;
  1022.         /* Here, lc is the match length - MIN_MATCH */
  1023.         dist--;             /* dist = match distance - 1 */
  1024.         Assert((ush)dist < (ush)MAX_DIST(s) &&
  1025.                (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
  1026.                (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
  1027.  
  1028.         s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
  1029.         s->dyn_dtree[d_code(dist)].Freq++;
  1030.     }
  1031.  
  1032. #ifdef TRUNCATE_BLOCK
  1033.     /* Try to guess if it is profitable to stop the current block here */
  1034.     if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
  1035.         /* Compute an upper bound for the compressed length */
  1036.         ulg out_length = (ulg)s->last_lit*8L;
  1037.         ulg in_length = (ulg)((long)s->strstart - s->block_start);
  1038.         int dcode;
  1039.         for (dcode = 0; dcode < D_CODES; dcode++) {
  1040.             out_length += (ulg)s->dyn_dtree[dcode].Freq *
  1041.                 (5L+extra_dbits[dcode]);
  1042.         }
  1043.         out_length >>= 3;
  1044.         Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
  1045.                s->last_lit, in_length, out_length,
  1046.                100L - out_length*100L/in_length));
  1047.         if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
  1048.     }
  1049. #endif
  1050.     return (s->last_lit == s->lit_bufsize-1);
  1051.     /* We avoid equality with lit_bufsize because of wraparound at 64K
  1052.      * on 16 bit machines and because stored blocks are restricted to
  1053.      * 64K-1 bytes.
  1054.      */
  1055. }
  1056.  
  1057. /* ===========================================================================
  1058.  * Send the block data compressed using the given Huffman trees
  1059.  */
  1060. local void compress_block(s, ltree, dtree)
  1061.     deflate_state *s;
  1062.     const ct_data *ltree; /* literal tree */
  1063.     const ct_data *dtree; /* distance tree */
  1064. {
  1065.     unsigned dist;      /* distance of matched string */
  1066.     int lc;             /* match length or unmatched char (if dist == 0) */
  1067.     unsigned lx = 0;    /* running index in l_buf */
  1068.     unsigned code;      /* the code to send */
  1069.     int extra;          /* number of extra bits to send */
  1070.  
  1071.     if (s->last_lit != 0) do {
  1072.         dist = s->d_buf[lx];
  1073.         lc = s->l_buf[lx++];
  1074.         if (dist == 0) {
  1075.             send_code(s, lc, ltree); /* send a literal byte */
  1076.             Tracecv(isgraph(lc), (stderr," '%c' ", lc));
  1077.         } else {
  1078.             /* Here, lc is the match length - MIN_MATCH */
  1079.             code = _length_code[lc];
  1080.             send_code(s, code+LITERALS+1, ltree); /* send the length code */
  1081.             extra = extra_lbits[code];
  1082.             if (extra != 0) {
  1083.                 lc -= base_length[code];
  1084.                 send_bits(s, lc, extra);       /* send the extra length bits */
  1085.             }
  1086.             dist--; /* dist is now the match distance - 1 */
  1087.             code = d_code(dist);
  1088.             Assert (code < D_CODES, "bad d_code");
  1089.  
  1090.             send_code(s, code, dtree);       /* send the distance code */
  1091.             extra = extra_dbits[code];
  1092.             if (extra != 0) {
  1093.                 dist -= base_dist[code];
  1094.                 send_bits(s, dist, extra);   /* send the extra distance bits */
  1095.             }
  1096.         } /* literal or match pair ? */
  1097.  
  1098.         /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
  1099.         Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
  1100.                "pendingBuf overflow");
  1101.  
  1102.     } while (lx < s->last_lit);
  1103.  
  1104.     send_code(s, END_BLOCK, ltree);
  1105. }
  1106.  
  1107. /* ===========================================================================
  1108.  * Check if the data type is TEXT or BINARY, using the following algorithm:
  1109.  * - TEXT if the two conditions below are satisfied:
  1110.  *    a) There are no non-portable control characters belonging to the
  1111.  *       "black list" (0..6, 14..25, 28..31).
  1112.  *    b) There is at least one printable character belonging to the
  1113.  *       "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
  1114.  * - BINARY otherwise.
  1115.  * - The following partially-portable control characters form a
  1116.  *   "gray list" that is ignored in this detection algorithm:
  1117.  *   (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
  1118.  * IN assertion: the fields Freq of dyn_ltree are set.
  1119.  */
  1120. local int detect_data_type(s)
  1121.     deflate_state *s;
  1122. {
  1123.     /* black_mask is the bit mask of black-listed bytes
  1124.      * set bits 0..6, 14..25, and 28..31
  1125.      * 0xf3ffc07f = binary 11110011111111111100000001111111
  1126.      */
  1127.     unsigned long black_mask = 0xf3ffc07fUL;
  1128.     int n;
  1129.  
  1130.     /* Check for non-textual ("black-listed") bytes. */
  1131.     for (n = 0; n <= 31; n++, black_mask >>= 1)
  1132.         if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
  1133.             return Z_BINARY;
  1134.  
  1135.     /* Check for textual ("white-listed") bytes. */
  1136.     if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
  1137.             || s->dyn_ltree[13].Freq != 0)
  1138.         return Z_TEXT;
  1139.     for (n = 32; n < LITERALS; n++)
  1140.         if (s->dyn_ltree[n].Freq != 0)
  1141.             return Z_TEXT;
  1142.  
  1143.     /* There are no "black-listed" or "white-listed" bytes:
  1144.      * this stream either is empty or has tolerated ("gray-listed") bytes only.
  1145.      */
  1146.     return Z_BINARY;
  1147. }
  1148.  
  1149. /* ===========================================================================
  1150.  * Reverse the first len bits of a code, using straightforward code (a faster
  1151.  * method would use a table)
  1152.  * IN assertion: 1 <= len <= 15
  1153.  */
  1154. local unsigned bi_reverse(code, len)
  1155.     unsigned code; /* the value to invert */
  1156.     int len;       /* its bit length */
  1157. {
  1158.     register unsigned res = 0;
  1159.     do {
  1160.         res |= code & 1;
  1161.         code >>= 1, res <<= 1;
  1162.     } while (--len > 0);
  1163.     return res >> 1;
  1164. }
  1165.  
  1166. /* ===========================================================================
  1167.  * Flush the bit buffer, keeping at most 7 bits in it.
  1168.  */
  1169. local void bi_flush(s)
  1170.     deflate_state *s;
  1171. {
  1172.     if (s->bi_valid == 16) {
  1173.         put_short(s, s->bi_buf);
  1174.         s->bi_buf = 0;
  1175.         s->bi_valid = 0;
  1176.     } else if (s->bi_valid >= 8) {
  1177.         put_byte(s, (Byte)s->bi_buf);
  1178.         s->bi_buf >>= 8;
  1179.         s->bi_valid -= 8;
  1180.     }
  1181. }
  1182.  
  1183. /* ===========================================================================
  1184.  * Flush the bit buffer and align the output on a byte boundary
  1185.  */
  1186. local void bi_windup(s)
  1187.     deflate_state *s;
  1188. {
  1189.     if (s->bi_valid > 8) {
  1190.         put_short(s, s->bi_buf);
  1191.     } else if (s->bi_valid > 0) {
  1192.         put_byte(s, (Byte)s->bi_buf);
  1193.     }
  1194.     s->bi_buf = 0;
  1195.     s->bi_valid = 0;
  1196. #ifdef DEBUG
  1197.     s->bits_sent = (s->bits_sent+7) & ~7;
  1198. #endif
  1199. }
  1200.  
  1201. /* ===========================================================================
  1202.  * Copy a stored block, storing first the length and its
  1203.  * one's complement if requested.
  1204.  */
  1205. local void copy_block(s, buf, len, header)
  1206.     deflate_state *s;
  1207.     charf    *buf;    /* the input data */
  1208.     unsigned len;     /* its length */
  1209.     int      header;  /* true if block header must be written */
  1210. {
  1211.     bi_windup(s);        /* align on byte boundary */
  1212.  
  1213.     if (header) {
  1214.         put_short(s, (ush)len);
  1215.         put_short(s, (ush)~len);
  1216. #ifdef DEBUG
  1217.         s->bits_sent += 2*16;
  1218. #endif
  1219.     }
  1220. #ifdef DEBUG
  1221.     s->bits_sent += (ulg)len<<3;
  1222. #endif
  1223.     while (len--) {
  1224.         put_byte(s, *buf++);
  1225.     }
  1226. }
  1227.