LCOV - code coverage report
Current view: top level - lib/zlib_deflate - deftree.c (source / functions) Hit Total Coverage
Test: landlock.info Lines: 0 374 0.0 %
Date: 2021-04-22 12:43:58 Functions: 0 19 0.0 %

          Line data    Source code
       1             : /* +++ trees.c */
       2             : /* trees.c -- output deflated data using Huffman coding
       3             :  * Copyright (C) 1995-1996 Jean-loup Gailly
       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             : /* From: trees.c,v 1.11 1996/07/24 13:41:06 me Exp $ */
      34             : 
      35             : /* #include "deflate.h" */
      36             : 
      37             : #include <linux/zutil.h>
      38             : #include <linux/bitrev.h>
      39             : #include "defutil.h"
      40             : 
      41             : #ifdef DEBUG_ZLIB
      42             : #  include <ctype.h>
      43             : #endif
      44             : 
      45             : /* ===========================================================================
      46             :  * Constants
      47             :  */
      48             : 
      49             : #define MAX_BL_BITS 7
      50             : /* Bit length codes must not exceed MAX_BL_BITS bits */
      51             : 
      52             : #define END_BLOCK 256
      53             : /* end of block literal code */
      54             : 
      55             : #define REP_3_6      16
      56             : /* repeat previous bit length 3-6 times (2 bits of repeat count) */
      57             : 
      58             : #define REPZ_3_10    17
      59             : /* repeat a zero length 3-10 times  (3 bits of repeat count) */
      60             : 
      61             : #define REPZ_11_138  18
      62             : /* repeat a zero length 11-138 times  (7 bits of repeat count) */
      63             : 
      64             : static const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
      65             :    = {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};
      66             : 
      67             : static const int extra_dbits[D_CODES] /* extra bits for each distance code */
      68             :    = {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};
      69             : 
      70             : static const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
      71             :    = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
      72             : 
      73             : static const uch bl_order[BL_CODES]
      74             :    = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
      75             : /* The lengths of the bit length codes are sent in order of decreasing
      76             :  * probability, to avoid transmitting the lengths for unused bit length codes.
      77             :  */
      78             : 
      79             : /* ===========================================================================
      80             :  * Local data. These are initialized only once.
      81             :  */
      82             : 
      83             : static ct_data static_ltree[L_CODES+2];
      84             : /* The static literal tree. Since the bit lengths are imposed, there is no
      85             :  * need for the L_CODES extra codes used during heap construction. However
      86             :  * The codes 286 and 287 are needed to build a canonical tree (see zlib_tr_init
      87             :  * below).
      88             :  */
      89             : 
      90             : static ct_data static_dtree[D_CODES];
      91             : /* The static distance tree. (Actually a trivial tree since all codes use
      92             :  * 5 bits.)
      93             :  */
      94             : 
      95             : static uch dist_code[512];
      96             : /* distance codes. The first 256 values correspond to the distances
      97             :  * 3 .. 258, the last 256 values correspond to the top 8 bits of
      98             :  * the 15 bit distances.
      99             :  */
     100             : 
     101             : static uch length_code[MAX_MATCH-MIN_MATCH+1];
     102             : /* length code for each normalized match length (0 == MIN_MATCH) */
     103             : 
     104             : static int base_length[LENGTH_CODES];
     105             : /* First normalized length for each code (0 = MIN_MATCH) */
     106             : 
     107             : static int base_dist[D_CODES];
     108             : /* First normalized distance for each code (0 = distance of 1) */
     109             : 
     110             : struct static_tree_desc_s {
     111             :     const ct_data *static_tree;  /* static tree or NULL */
     112             :     const int *extra_bits;       /* extra bits for each code or NULL */
     113             :     int     extra_base;          /* base index for extra_bits */
     114             :     int     elems;               /* max number of elements in the tree */
     115             :     int     max_length;          /* max bit length for the codes */
     116             : };
     117             : 
     118             : static static_tree_desc  static_l_desc =
     119             : {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
     120             : 
     121             : static static_tree_desc  static_d_desc =
     122             : {static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};
     123             : 
     124             : static static_tree_desc  static_bl_desc =
     125             : {(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
     126             : 
     127             : /* ===========================================================================
     128             :  * Local (static) routines in this file.
     129             :  */
     130             : 
     131             : static void tr_static_init (void);
     132             : static void init_block     (deflate_state *s);
     133             : static void pqdownheap     (deflate_state *s, ct_data *tree, int k);
     134             : static void gen_bitlen     (deflate_state *s, tree_desc *desc);
     135             : static void gen_codes      (ct_data *tree, int max_code, ush *bl_count);
     136             : static void build_tree     (deflate_state *s, tree_desc *desc);
     137             : static void scan_tree      (deflate_state *s, ct_data *tree, int max_code);
     138             : static void send_tree      (deflate_state *s, ct_data *tree, int max_code);
     139             : static int  build_bl_tree  (deflate_state *s);
     140             : static void send_all_trees (deflate_state *s, int lcodes, int dcodes,
     141             :                            int blcodes);
     142             : static void compress_block (deflate_state *s, ct_data *ltree,
     143             :                            ct_data *dtree);
     144             : static void set_data_type  (deflate_state *s);
     145             : static void bi_flush       (deflate_state *s);
     146             : static void copy_block     (deflate_state *s, char *buf, unsigned len,
     147             :                            int header);
     148             : 
     149             : #ifndef DEBUG_ZLIB
     150             : #  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
     151             :    /* Send a code of the given tree. c and tree must not have side effects */
     152             : 
     153             : #else /* DEBUG_ZLIB */
     154             : #  define send_code(s, c, tree) \
     155             :      { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
     156             :        send_bits(s, tree[c].Code, tree[c].Len); }
     157             : #endif
     158             : 
     159             : #define d_code(dist) \
     160             :    ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)])
     161             : /* Mapping from a distance to a distance code. dist is the distance - 1 and
     162             :  * must not have side effects. dist_code[256] and dist_code[257] are never
     163             :  * used.
     164             :  */
     165             : 
     166             : /* ===========================================================================
     167             :  * Initialize the various 'constant' tables. In a multi-threaded environment,
     168             :  * this function may be called by two threads concurrently, but this is
     169             :  * harmless since both invocations do exactly the same thing.
     170             :  */
     171           0 : static void tr_static_init(void)
     172             : {
     173           0 :     static int static_init_done;
     174           0 :     int n;        /* iterates over tree elements */
     175           0 :     int bits;     /* bit counter */
     176           0 :     int length;   /* length value */
     177           0 :     int code;     /* code value */
     178           0 :     int dist;     /* distance index */
     179           0 :     ush bl_count[MAX_BITS+1];
     180             :     /* number of codes at each bit length for an optimal tree */
     181             : 
     182           0 :     if (static_init_done) return;
     183             : 
     184             :     /* Initialize the mapping length (0..255) -> length code (0..28) */
     185             :     length = 0;
     186           0 :     for (code = 0; code < LENGTH_CODES-1; code++) {
     187           0 :         base_length[code] = length;
     188           0 :         for (n = 0; n < (1<<extra_lbits[code]); n++) {
     189           0 :             length_code[length++] = (uch)code;
     190             :         }
     191             :     }
     192           0 :     Assert (length == 256, "tr_static_init: length != 256");
     193             :     /* Note that the length 255 (match length 258) can be represented
     194             :      * in two different ways: code 284 + 5 bits or code 285, so we
     195             :      * overwrite length_code[255] to use the best encoding:
     196             :      */
     197           0 :     length_code[length-1] = (uch)code;
     198             : 
     199             :     /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
     200           0 :     dist = 0;
     201           0 :     for (code = 0 ; code < 16; code++) {
     202           0 :         base_dist[code] = dist;
     203           0 :         for (n = 0; n < (1<<extra_dbits[code]); n++) {
     204           0 :             dist_code[dist++] = (uch)code;
     205             :         }
     206             :     }
     207           0 :     Assert (dist == 256, "tr_static_init: dist != 256");
     208           0 :     dist >>= 7; /* from now on, all distances are divided by 128 */
     209           0 :     for ( ; code < D_CODES; code++) {
     210           0 :         base_dist[code] = dist << 7;
     211           0 :         for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
     212           0 :             dist_code[256 + dist++] = (uch)code;
     213             :         }
     214             :     }
     215             :     Assert (dist == 256, "tr_static_init: 256+dist != 512");
     216             : 
     217             :     /* Construct the codes of the static literal tree */
     218           0 :     for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
     219             :     n = 0;
     220           0 :     while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
     221           0 :     while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
     222           0 :     while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
     223           0 :     while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
     224             :     /* Codes 286 and 287 do not exist, but we must include them in the
     225             :      * tree construction to get a canonical Huffman tree (longest code
     226             :      * all ones)
     227             :      */
     228           0 :     gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
     229             : 
     230             :     /* The static distance tree is trivial: */
     231           0 :     for (n = 0; n < D_CODES; n++) {
     232           0 :         static_dtree[n].Len = 5;
     233           0 :         static_dtree[n].Code = bitrev32((u32)n) >> (32 - 5);
     234             :     }
     235           0 :     static_init_done = 1;
     236             : }
     237             : 
     238             : /* ===========================================================================
     239             :  * Initialize the tree data structures for a new zlib stream.
     240             :  */
     241           0 : void zlib_tr_init(
     242             :         deflate_state *s
     243             : )
     244             : {
     245           0 :     tr_static_init();
     246             : 
     247           0 :     s->compressed_len = 0L;
     248             : 
     249           0 :     s->l_desc.dyn_tree = s->dyn_ltree;
     250           0 :     s->l_desc.stat_desc = &static_l_desc;
     251             : 
     252           0 :     s->d_desc.dyn_tree = s->dyn_dtree;
     253           0 :     s->d_desc.stat_desc = &static_d_desc;
     254             : 
     255           0 :     s->bl_desc.dyn_tree = s->bl_tree;
     256           0 :     s->bl_desc.stat_desc = &static_bl_desc;
     257             : 
     258           0 :     s->bi_buf = 0;
     259           0 :     s->bi_valid = 0;
     260           0 :     s->last_eob_len = 8; /* enough lookahead for inflate */
     261             : #ifdef DEBUG_ZLIB
     262             :     s->bits_sent = 0L;
     263             : #endif
     264             : 
     265             :     /* Initialize the first block of the first file: */
     266           0 :     init_block(s);
     267           0 : }
     268             : 
     269             : /* ===========================================================================
     270             :  * Initialize a new block.
     271             :  */
     272           0 : static void init_block(
     273             :         deflate_state *s
     274             : )
     275             : {
     276           0 :     int n; /* iterates over tree elements */
     277             : 
     278             :     /* Initialize the trees. */
     279           0 :     for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
     280           0 :     for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
     281           0 :     for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
     282             : 
     283           0 :     s->dyn_ltree[END_BLOCK].Freq = 1;
     284           0 :     s->opt_len = s->static_len = 0L;
     285           0 :     s->last_lit = s->matches = 0;
     286           0 : }
     287             : 
     288             : #define SMALLEST 1
     289             : /* Index within the heap array of least frequent node in the Huffman tree */
     290             : 
     291             : 
     292             : /* ===========================================================================
     293             :  * Remove the smallest element from the heap and recreate the heap with
     294             :  * one less element. Updates heap and heap_len.
     295             :  */
     296             : #define pqremove(s, tree, top) \
     297             : {\
     298             :     top = s->heap[SMALLEST]; \
     299             :     s->heap[SMALLEST] = s->heap[s->heap_len--]; \
     300             :     pqdownheap(s, tree, SMALLEST); \
     301             : }
     302             : 
     303             : /* ===========================================================================
     304             :  * Compares to subtrees, using the tree depth as tie breaker when
     305             :  * the subtrees have equal frequency. This minimizes the worst case length.
     306             :  */
     307             : #define smaller(tree, n, m, depth) \
     308             :    (tree[n].Freq < tree[m].Freq || \
     309             :    (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
     310             : 
     311             : /* ===========================================================================
     312             :  * Restore the heap property by moving down the tree starting at node k,
     313             :  * exchanging a node with the smallest of its two sons if necessary, stopping
     314             :  * when the heap property is re-established (each father smaller than its
     315             :  * two sons).
     316             :  */
     317           0 : static void pqdownheap(
     318             :         deflate_state *s,
     319             :         ct_data *tree,  /* the tree to restore */
     320             :         int k           /* node to move down */
     321             : )
     322             : {
     323           0 :     int v = s->heap[k];
     324           0 :     int j = k << 1;  /* left son of k */
     325           0 :     while (j <= s->heap_len) {
     326             :         /* Set j to the smallest of the two sons: */
     327           0 :         if (j < s->heap_len &&
     328           0 :             smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
     329           0 :             j++;
     330             :         }
     331             :         /* Exit if v is smaller than both sons */
     332           0 :         if (smaller(tree, v, s->heap[j], s->depth)) break;
     333             : 
     334             :         /* Exchange v with the smallest son */
     335           0 :         s->heap[k] = s->heap[j];  k = j;
     336             : 
     337             :         /* And continue down the tree, setting j to the left son of k */
     338           0 :         j <<= 1;
     339             :     }
     340           0 :     s->heap[k] = v;
     341           0 : }
     342             : 
     343             : /* ===========================================================================
     344             :  * Compute the optimal bit lengths for a tree and update the total bit length
     345             :  * for the current block.
     346             :  * IN assertion: the fields freq and dad are set, heap[heap_max] and
     347             :  *    above are the tree nodes sorted by increasing frequency.
     348             :  * OUT assertions: the field len is set to the optimal bit length, the
     349             :  *     array bl_count contains the frequencies for each bit length.
     350             :  *     The length opt_len is updated; static_len is also updated if stree is
     351             :  *     not null.
     352             :  */
     353           0 : static void gen_bitlen(
     354             :         deflate_state *s,
     355             :         tree_desc *desc    /* the tree descriptor */
     356             : )
     357             : {
     358           0 :     ct_data *tree        = desc->dyn_tree;
     359           0 :     int max_code         = desc->max_code;
     360           0 :     const ct_data *stree = desc->stat_desc->static_tree;
     361           0 :     const int *extra     = desc->stat_desc->extra_bits;
     362           0 :     int base             = desc->stat_desc->extra_base;
     363           0 :     int max_length       = desc->stat_desc->max_length;
     364           0 :     int h;              /* heap index */
     365           0 :     int n, m;           /* iterate over the tree elements */
     366           0 :     int bits;           /* bit length */
     367           0 :     int xbits;          /* extra bits */
     368           0 :     ush f;              /* frequency */
     369           0 :     int overflow = 0;   /* number of elements with bit length too large */
     370             : 
     371           0 :     for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
     372             : 
     373             :     /* In a first pass, compute the optimal bit lengths (which may
     374             :      * overflow in the case of the bit length tree).
     375             :      */
     376           0 :     tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
     377             : 
     378           0 :     for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
     379           0 :         n = s->heap[h];
     380           0 :         bits = tree[tree[n].Dad].Len + 1;
     381           0 :         if (bits > max_length) bits = max_length, overflow++;
     382           0 :         tree[n].Len = (ush)bits;
     383             :         /* We overwrite tree[n].Dad which is no longer needed */
     384             : 
     385           0 :         if (n > max_code) continue; /* not a leaf node */
     386             : 
     387           0 :         s->bl_count[bits]++;
     388           0 :         xbits = 0;
     389           0 :         if (n >= base) xbits = extra[n-base];
     390           0 :         f = tree[n].Freq;
     391           0 :         s->opt_len += (ulg)f * (bits + xbits);
     392           0 :         if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
     393             :     }
     394           0 :     if (overflow == 0) return;
     395             : 
     396           0 :     Trace((stderr,"\nbit length overflow\n"));
     397             :     /* This happens for example on obj2 and pic of the Calgary corpus */
     398             : 
     399             :     /* Find the first bit length which could increase: */
     400           0 :     do {
     401           0 :         bits = max_length-1;
     402           0 :         while (s->bl_count[bits] == 0) bits--;
     403           0 :         s->bl_count[bits]--;      /* move one leaf down the tree */
     404           0 :         s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
     405           0 :         s->bl_count[max_length]--;
     406             :         /* The brother of the overflow item also moves one step up,
     407             :          * but this does not affect bl_count[max_length]
     408             :          */
     409           0 :         overflow -= 2;
     410           0 :     } while (overflow > 0);
     411             : 
     412             :     /* Now recompute all bit lengths, scanning in increasing frequency.
     413             :      * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
     414             :      * lengths instead of fixing only the wrong ones. This idea is taken
     415             :      * from 'ar' written by Haruhiko Okumura.)
     416             :      */
     417           0 :     for (bits = max_length; bits != 0; bits--) {
     418           0 :         n = s->bl_count[bits];
     419           0 :         while (n != 0) {
     420           0 :             m = s->heap[--h];
     421           0 :             if (m > max_code) continue;
     422           0 :             if (tree[m].Len != (unsigned) bits) {
     423           0 :                 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
     424           0 :                 s->opt_len += ((long)bits - (long)tree[m].Len)
     425           0 :                               *(long)tree[m].Freq;
     426           0 :                 tree[m].Len = (ush)bits;
     427             :             }
     428           0 :             n--;
     429             :         }
     430             :     }
     431             : }
     432             : 
     433             : /* ===========================================================================
     434             :  * Generate the codes for a given tree and bit counts (which need not be
     435             :  * optimal).
     436             :  * IN assertion: the array bl_count contains the bit length statistics for
     437             :  * the given tree and the field len is set for all tree elements.
     438             :  * OUT assertion: the field code is set for all tree elements of non
     439             :  *     zero code length.
     440             :  */
     441           0 : static void gen_codes(
     442             :         ct_data *tree,             /* the tree to decorate */
     443             :         int max_code,              /* largest code with non zero frequency */
     444             :         ush *bl_count             /* number of codes at each bit length */
     445             : )
     446             : {
     447           0 :     ush next_code[MAX_BITS+1]; /* next code value for each bit length */
     448           0 :     ush code = 0;              /* running code value */
     449           0 :     int bits;                  /* bit index */
     450           0 :     int n;                     /* code index */
     451             : 
     452             :     /* The distribution counts are first used to generate the code values
     453             :      * without bit reversal.
     454             :      */
     455           0 :     for (bits = 1; bits <= MAX_BITS; bits++) {
     456           0 :         next_code[bits] = code = (code + bl_count[bits-1]) << 1;
     457             :     }
     458             :     /* Check that the bit counts in bl_count are consistent. The last code
     459             :      * must be all ones.
     460             :      */
     461             :     Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
     462             :             "inconsistent bit counts");
     463             :     Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
     464             : 
     465           0 :     for (n = 0;  n <= max_code; n++) {
     466           0 :         int len = tree[n].Len;
     467           0 :         if (len == 0) continue;
     468             :         /* Now reverse the bits */
     469           0 :         tree[n].Code = bitrev32((u32)(next_code[len]++)) >> (32 - len);
     470             : 
     471             :         Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
     472           0 :              n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
     473             :     }
     474           0 : }
     475             : 
     476             : /* ===========================================================================
     477             :  * Construct one Huffman tree and assigns the code bit strings and lengths.
     478             :  * Update the total bit length for the current block.
     479             :  * IN assertion: the field freq is set for all tree elements.
     480             :  * OUT assertions: the fields len and code are set to the optimal bit length
     481             :  *     and corresponding code. The length opt_len is updated; static_len is
     482             :  *     also updated if stree is not null. The field max_code is set.
     483             :  */
     484           0 : static void build_tree(
     485             :         deflate_state *s,
     486             :         tree_desc *desc  /* the tree descriptor */
     487             : )
     488             : {
     489           0 :     ct_data *tree         = desc->dyn_tree;
     490           0 :     const ct_data *stree  = desc->stat_desc->static_tree;
     491           0 :     int elems             = desc->stat_desc->elems;
     492           0 :     int n, m;          /* iterate over heap elements */
     493           0 :     int max_code = -1; /* largest code with non zero frequency */
     494           0 :     int node;          /* new node being created */
     495             : 
     496             :     /* Construct the initial heap, with least frequent element in
     497             :      * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
     498             :      * heap[0] is not used.
     499             :      */
     500           0 :     s->heap_len = 0, s->heap_max = HEAP_SIZE;
     501             : 
     502           0 :     for (n = 0; n < elems; n++) {
     503           0 :         if (tree[n].Freq != 0) {
     504           0 :             s->heap[++(s->heap_len)] = max_code = n;
     505           0 :             s->depth[n] = 0;
     506             :         } else {
     507           0 :             tree[n].Len = 0;
     508             :         }
     509             :     }
     510             : 
     511             :     /* The pkzip format requires that at least one distance code exists,
     512             :      * and that at least one bit should be sent even if there is only one
     513             :      * possible code. So to avoid special checks later on we force at least
     514             :      * two codes of non zero frequency.
     515             :      */
     516           0 :     while (s->heap_len < 2) {
     517           0 :         node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
     518           0 :         tree[node].Freq = 1;
     519           0 :         s->depth[node] = 0;
     520           0 :         s->opt_len--; if (stree) s->static_len -= stree[node].Len;
     521             :         /* node is 0 or 1 so it does not have extra bits */
     522             :     }
     523           0 :     desc->max_code = max_code;
     524             : 
     525             :     /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
     526             :      * establish sub-heaps of increasing lengths:
     527             :      */
     528           0 :     for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
     529             : 
     530             :     /* Construct the Huffman tree by repeatedly combining the least two
     531             :      * frequent nodes.
     532             :      */
     533             :     node = elems;              /* next internal node of the tree */
     534           0 :     do {
     535           0 :         pqremove(s, tree, n);  /* n = node of least frequency */
     536           0 :         m = s->heap[SMALLEST]; /* m = node of next least frequency */
     537             : 
     538           0 :         s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
     539           0 :         s->heap[--(s->heap_max)] = m;
     540             : 
     541             :         /* Create a new node father of n and m */
     542           0 :         tree[node].Freq = tree[n].Freq + tree[m].Freq;
     543           0 :         s->depth[node] = (uch) (max(s->depth[n], s->depth[m]) + 1);
     544           0 :         tree[n].Dad = tree[m].Dad = (ush)node;
     545             : #ifdef DUMP_BL_TREE
     546             :         if (tree == s->bl_tree) {
     547             :             fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
     548             :                     node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
     549             :         }
     550             : #endif
     551             :         /* and insert the new node in the heap */
     552           0 :         s->heap[SMALLEST] = node++;
     553           0 :         pqdownheap(s, tree, SMALLEST);
     554             : 
     555           0 :     } while (s->heap_len >= 2);
     556             : 
     557           0 :     s->heap[--(s->heap_max)] = s->heap[SMALLEST];
     558             : 
     559             :     /* At this point, the fields freq and dad are set. We can now
     560             :      * generate the bit lengths.
     561             :      */
     562           0 :     gen_bitlen(s, (tree_desc *)desc);
     563             : 
     564             :     /* The field len is now set, we can generate the bit codes */
     565           0 :     gen_codes ((ct_data *)tree, max_code, s->bl_count);
     566           0 : }
     567             : 
     568             : /* ===========================================================================
     569             :  * Scan a literal or distance tree to determine the frequencies of the codes
     570             :  * in the bit length tree.
     571             :  */
     572           0 : static void scan_tree(
     573             :         deflate_state *s,
     574             :         ct_data *tree,   /* the tree to be scanned */
     575             :         int max_code     /* and its largest code of non zero frequency */
     576             : )
     577             : {
     578           0 :     int n;                     /* iterates over all tree elements */
     579           0 :     int prevlen = -1;          /* last emitted length */
     580           0 :     int curlen;                /* length of current code */
     581           0 :     int nextlen = tree[0].Len; /* length of next code */
     582           0 :     int count = 0;             /* repeat count of the current code */
     583           0 :     int max_count = 7;         /* max repeat count */
     584           0 :     int min_count = 4;         /* min repeat count */
     585             : 
     586           0 :     if (nextlen == 0) max_count = 138, min_count = 3;
     587           0 :     tree[max_code+1].Len = (ush)0xffff; /* guard */
     588             : 
     589           0 :     for (n = 0; n <= max_code; n++) {
     590           0 :         curlen = nextlen; nextlen = tree[n+1].Len;
     591           0 :         if (++count < max_count && curlen == nextlen) {
     592           0 :             continue;
     593           0 :         } else if (count < min_count) {
     594           0 :             s->bl_tree[curlen].Freq += count;
     595           0 :         } else if (curlen != 0) {
     596           0 :             if (curlen != prevlen) s->bl_tree[curlen].Freq++;
     597           0 :             s->bl_tree[REP_3_6].Freq++;
     598           0 :         } else if (count <= 10) {
     599           0 :             s->bl_tree[REPZ_3_10].Freq++;
     600             :         } else {
     601           0 :             s->bl_tree[REPZ_11_138].Freq++;
     602             :         }
     603           0 :         count = 0; prevlen = curlen;
     604           0 :         if (nextlen == 0) {
     605             :             max_count = 138, min_count = 3;
     606           0 :         } else if (curlen == nextlen) {
     607             :             max_count = 6, min_count = 3;
     608             :         } else {
     609           0 :             max_count = 7, min_count = 4;
     610             :         }
     611             :     }
     612           0 : }
     613             : 
     614             : /* ===========================================================================
     615             :  * Send a literal or distance tree in compressed form, using the codes in
     616             :  * bl_tree.
     617             :  */
     618           0 : static void send_tree(
     619             :         deflate_state *s,
     620             :         ct_data *tree, /* the tree to be scanned */
     621             :         int max_code   /* and its largest code of non zero frequency */
     622             : )
     623             : {
     624           0 :     int n;                     /* iterates over all tree elements */
     625           0 :     int prevlen = -1;          /* last emitted length */
     626           0 :     int curlen;                /* length of current code */
     627           0 :     int nextlen = tree[0].Len; /* length of next code */
     628           0 :     int count = 0;             /* repeat count of the current code */
     629           0 :     int max_count = 7;         /* max repeat count */
     630           0 :     int min_count = 4;         /* min repeat count */
     631             : 
     632             :     /* tree[max_code+1].Len = -1; */  /* guard already set */
     633           0 :     if (nextlen == 0) max_count = 138, min_count = 3;
     634             : 
     635           0 :     for (n = 0; n <= max_code; n++) {
     636           0 :         curlen = nextlen; nextlen = tree[n+1].Len;
     637           0 :         if (++count < max_count && curlen == nextlen) {
     638           0 :             continue;
     639           0 :         } else if (count < min_count) {
     640           0 :             do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
     641             : 
     642           0 :         } else if (curlen != 0) {
     643           0 :             if (curlen != prevlen) {
     644           0 :                 send_code(s, curlen, s->bl_tree); count--;
     645             :             }
     646           0 :             Assert(count >= 3 && count <= 6, " 3_6?");
     647           0 :             send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
     648             : 
     649           0 :         } else if (count <= 10) {
     650           0 :             send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
     651             : 
     652             :         } else {
     653           0 :             send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
     654             :         }
     655           0 :         count = 0; prevlen = curlen;
     656           0 :         if (nextlen == 0) {
     657             :             max_count = 138, min_count = 3;
     658           0 :         } else if (curlen == nextlen) {
     659             :             max_count = 6, min_count = 3;
     660             :         } else {
     661           0 :             max_count = 7, min_count = 4;
     662             :         }
     663             :     }
     664           0 : }
     665             : 
     666             : /* ===========================================================================
     667             :  * Construct the Huffman tree for the bit lengths and return the index in
     668             :  * bl_order of the last bit length code to send.
     669             :  */
     670           0 : static int build_bl_tree(
     671             :         deflate_state *s
     672             : )
     673             : {
     674           0 :     int max_blindex;  /* index of last bit length code of non zero freq */
     675             : 
     676             :     /* Determine the bit length frequencies for literal and distance trees */
     677           0 :     scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
     678           0 :     scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
     679             : 
     680             :     /* Build the bit length tree: */
     681           0 :     build_tree(s, (tree_desc *)(&(s->bl_desc)));
     682             :     /* opt_len now includes the length of the tree representations, except
     683             :      * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
     684             :      */
     685             : 
     686             :     /* Determine the number of bit length codes to send. The pkzip format
     687             :      * requires that at least 4 bit length codes be sent. (appnote.txt says
     688             :      * 3 but the actual value used is 4.)
     689             :      */
     690           0 :     for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
     691           0 :         if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
     692             :     }
     693             :     /* Update opt_len to include the bit length tree and counts */
     694           0 :     s->opt_len += 3*(max_blindex+1) + 5+5+4;
     695             :     Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
     696           0 :             s->opt_len, s->static_len));
     697             : 
     698           0 :     return max_blindex;
     699             : }
     700             : 
     701             : /* ===========================================================================
     702             :  * Send the header for a block using dynamic Huffman trees: the counts, the
     703             :  * lengths of the bit length codes, the literal tree and the distance tree.
     704             :  * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
     705             :  */
     706           0 : static void send_all_trees(
     707             :         deflate_state *s,
     708             :         int lcodes,  /* number of codes for each tree */
     709             :         int dcodes,  /* number of codes for each tree */
     710             :         int blcodes  /* number of codes for each tree */
     711             : )
     712             : {
     713           0 :     int rank;                    /* index in bl_order */
     714             : 
     715           0 :     Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
     716             :     Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
     717           0 :             "too many codes");
     718           0 :     Tracev((stderr, "\nbl counts: "));
     719           0 :     send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
     720           0 :     send_bits(s, dcodes-1,   5);
     721           0 :     send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
     722           0 :     for (rank = 0; rank < blcodes; rank++) {
     723           0 :         Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
     724           0 :         send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
     725             :     }
     726           0 :     Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
     727             : 
     728           0 :     send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
     729           0 :     Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
     730             : 
     731           0 :     send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
     732           0 :     Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
     733           0 : }
     734             : 
     735             : /* ===========================================================================
     736             :  * Send a stored block
     737             :  */
     738           0 : void zlib_tr_stored_block(
     739             :         deflate_state *s,
     740             :         char *buf,        /* input block */
     741             :         ulg stored_len,   /* length of input block */
     742             :         int eof           /* true if this is the last block for a file */
     743             : )
     744             : {
     745           0 :     send_bits(s, (STORED_BLOCK<<1)+eof, 3);  /* send block type */
     746           0 :     s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
     747           0 :     s->compressed_len += (stored_len + 4) << 3;
     748             : 
     749           0 :     copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
     750           0 : }
     751             : 
     752             : /* Send just the `stored block' type code without any length bytes or data.
     753             :  */
     754           0 : void zlib_tr_stored_type_only(
     755             :         deflate_state *s
     756             : )
     757             : {
     758           0 :     send_bits(s, (STORED_BLOCK << 1), 3);
     759           0 :     bi_windup(s);
     760           0 :     s->compressed_len = (s->compressed_len + 3) & ~7L;
     761           0 : }
     762             : 
     763             : 
     764             : /* ===========================================================================
     765             :  * Send one empty static block to give enough lookahead for inflate.
     766             :  * This takes 10 bits, of which 7 may remain in the bit buffer.
     767             :  * The current inflate code requires 9 bits of lookahead. If the
     768             :  * last two codes for the previous block (real code plus EOB) were coded
     769             :  * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
     770             :  * the last real code. In this case we send two empty static blocks instead
     771             :  * of one. (There are no problems if the previous block is stored or fixed.)
     772             :  * To simplify the code, we assume the worst case of last real code encoded
     773             :  * on one bit only.
     774             :  */
     775           0 : void zlib_tr_align(
     776             :         deflate_state *s
     777             : )
     778             : {
     779           0 :     send_bits(s, STATIC_TREES<<1, 3);
     780           0 :     send_code(s, END_BLOCK, static_ltree);
     781           0 :     s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
     782           0 :     bi_flush(s);
     783             :     /* Of the 10 bits for the empty block, we have already sent
     784             :      * (10 - bi_valid) bits. The lookahead for the last real code (before
     785             :      * the EOB of the previous block) was thus at least one plus the length
     786             :      * of the EOB plus what we have just sent of the empty static block.
     787             :      */
     788           0 :     if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
     789           0 :         send_bits(s, STATIC_TREES<<1, 3);
     790           0 :         send_code(s, END_BLOCK, static_ltree);
     791           0 :         s->compressed_len += 10L;
     792           0 :         bi_flush(s);
     793             :     }
     794           0 :     s->last_eob_len = 7;
     795           0 : }
     796             : 
     797             : /* ===========================================================================
     798             :  * Determine the best encoding for the current block: dynamic trees, static
     799             :  * trees or store, and output the encoded block to the zip file. This function
     800             :  * returns the total compressed length for the file so far.
     801             :  */
     802           0 : ulg zlib_tr_flush_block(
     803             :         deflate_state *s,
     804             :         char *buf,        /* input block, or NULL if too old */
     805             :         ulg stored_len,   /* length of input block */
     806             :         int eof           /* true if this is the last block for a file */
     807             : )
     808             : {
     809           0 :     ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
     810           0 :     int max_blindex = 0;  /* index of last bit length code of non zero freq */
     811             : 
     812             :     /* Build the Huffman trees unless a stored block is forced */
     813           0 :     if (s->level > 0) {
     814             : 
     815             :          /* Check if the file is ascii or binary */
     816           0 :         if (s->data_type == Z_UNKNOWN) set_data_type(s);
     817             : 
     818             :         /* Construct the literal and distance trees */
     819           0 :         build_tree(s, (tree_desc *)(&(s->l_desc)));
     820             :         Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
     821           0 :                 s->static_len));
     822             : 
     823           0 :         build_tree(s, (tree_desc *)(&(s->d_desc)));
     824             :         Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
     825           0 :                 s->static_len));
     826             :         /* At this point, opt_len and static_len are the total bit lengths of
     827             :          * the compressed block data, excluding the tree representations.
     828             :          */
     829             : 
     830             :         /* Build the bit length tree for the above two trees, and get the index
     831             :          * in bl_order of the last bit length code to send.
     832             :          */
     833           0 :         max_blindex = build_bl_tree(s);
     834             : 
     835             :         /* Determine the best encoding. Compute first the block length in bytes*/
     836           0 :         opt_lenb = (s->opt_len+3+7)>>3;
     837           0 :         static_lenb = (s->static_len+3+7)>>3;
     838             : 
     839             :         Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
     840             :                 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
     841           0 :                 s->last_lit));
     842             : 
     843           0 :         if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
     844             : 
     845             :     } else {
     846           0 :         Assert(buf != (char*)0, "lost buf");
     847           0 :         opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
     848             :     }
     849             : 
     850             :     /* If compression failed and this is the first and last block,
     851             :      * and if the .zip file can be seeked (to rewrite the local header),
     852             :      * the whole file is transformed into a stored file:
     853             :      */
     854             : #ifdef STORED_FILE_OK
     855             : #  ifdef FORCE_STORED_FILE
     856             :     if (eof && s->compressed_len == 0L) { /* force stored file */
     857             : #  else
     858             :     if (stored_len <= opt_lenb && eof && s->compressed_len==0L && seekable()) {
     859             : #  endif
     860             :         /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
     861             :         if (buf == (char*)0) error ("block vanished");
     862             : 
     863             :         copy_block(s, buf, (unsigned)stored_len, 0); /* without header */
     864             :         s->compressed_len = stored_len << 3;
     865             :         s->method = STORED;
     866             :     } else
     867             : #endif /* STORED_FILE_OK */
     868             : 
     869             : #ifdef FORCE_STORED
     870             :     if (buf != (char*)0) { /* force stored block */
     871             : #else
     872           0 :     if (stored_len+4 <= opt_lenb && buf != (char*)0) {
     873             :                        /* 4: two words for the lengths */
     874             : #endif
     875             :         /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
     876             :          * Otherwise we can't have processed more than WSIZE input bytes since
     877             :          * the last block flush, because compression would have been
     878             :          * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
     879             :          * transform a block into a stored block.
     880             :          */
     881           0 :         zlib_tr_stored_block(s, buf, stored_len, eof);
     882             : 
     883             : #ifdef FORCE_STATIC
     884             :     } else if (static_lenb >= 0) { /* force static trees */
     885             : #else
     886           0 :     } else if (static_lenb == opt_lenb) {
     887             : #endif
     888           0 :         send_bits(s, (STATIC_TREES<<1)+eof, 3);
     889           0 :         compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
     890           0 :         s->compressed_len += 3 + s->static_len;
     891             :     } else {
     892           0 :         send_bits(s, (DYN_TREES<<1)+eof, 3);
     893           0 :         send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
     894             :                        max_blindex+1);
     895           0 :         compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
     896           0 :         s->compressed_len += 3 + s->opt_len;
     897             :     }
     898           0 :     Assert (s->compressed_len == s->bits_sent, "bad compressed size");
     899           0 :     init_block(s);
     900             : 
     901           0 :     if (eof) {
     902           0 :         bi_windup(s);
     903           0 :         s->compressed_len += 7;  /* align on byte boundary */
     904             :     }
     905             :     Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
     906           0 :            s->compressed_len-7*eof));
     907             : 
     908           0 :     return s->compressed_len >> 3;
     909             : }
     910             : 
     911             : /* ===========================================================================
     912             :  * Save the match info and tally the frequency counts. Return true if
     913             :  * the current block must be flushed.
     914             :  */
     915           0 : int zlib_tr_tally(
     916             :         deflate_state *s,
     917             :         unsigned dist,  /* distance of matched string */
     918             :         unsigned lc     /* match length-MIN_MATCH or unmatched char (if dist==0) */
     919             : )
     920             : {
     921           0 :     s->d_buf[s->last_lit] = (ush)dist;
     922           0 :     s->l_buf[s->last_lit++] = (uch)lc;
     923           0 :     if (dist == 0) {
     924             :         /* lc is the unmatched char */
     925           0 :         s->dyn_ltree[lc].Freq++;
     926             :     } else {
     927           0 :         s->matches++;
     928             :         /* Here, lc is the match length - MIN_MATCH */
     929           0 :         dist--;             /* dist = match distance - 1 */
     930             :         Assert((ush)dist < (ush)MAX_DIST(s) &&
     931             :                (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
     932           0 :                (ush)d_code(dist) < (ush)D_CODES,  "zlib_tr_tally: bad match");
     933             : 
     934           0 :         s->dyn_ltree[length_code[lc]+LITERALS+1].Freq++;
     935           0 :         s->dyn_dtree[d_code(dist)].Freq++;
     936             :     }
     937             : 
     938             :     /* Try to guess if it is profitable to stop the current block here */
     939           0 :     if ((s->last_lit & 0xfff) == 0 && s->level > 2) {
     940             :         /* Compute an upper bound for the compressed length */
     941           0 :         ulg out_length = (ulg)s->last_lit*8L;
     942           0 :         ulg in_length = (ulg)((long)s->strstart - s->block_start);
     943           0 :         int dcode;
     944           0 :         for (dcode = 0; dcode < D_CODES; dcode++) {
     945           0 :             out_length += (ulg)s->dyn_dtree[dcode].Freq *
     946           0 :                 (5L+extra_dbits[dcode]);
     947             :         }
     948           0 :         out_length >>= 3;
     949             :         Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
     950             :                s->last_lit, in_length, out_length,
     951           0 :                100L - out_length*100L/in_length));
     952           0 :         if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
     953             :     }
     954           0 :     return (s->last_lit == s->lit_bufsize-1);
     955             :     /* We avoid equality with lit_bufsize because of wraparound at 64K
     956             :      * on 16 bit machines and because stored blocks are restricted to
     957             :      * 64K-1 bytes.
     958             :      */
     959             : }
     960             : 
     961             : /* ===========================================================================
     962             :  * Send the block data compressed using the given Huffman trees
     963             :  */
     964           0 : static void compress_block(
     965             :         deflate_state *s,
     966             :         ct_data *ltree, /* literal tree */
     967             :         ct_data *dtree  /* distance tree */
     968             : )
     969             : {
     970           0 :     unsigned dist;      /* distance of matched string */
     971           0 :     int lc;             /* match length or unmatched char (if dist == 0) */
     972           0 :     unsigned lx = 0;    /* running index in l_buf */
     973           0 :     unsigned code;      /* the code to send */
     974           0 :     int extra;          /* number of extra bits to send */
     975             : 
     976           0 :     if (s->last_lit != 0) do {
     977           0 :         dist = s->d_buf[lx];
     978           0 :         lc = s->l_buf[lx++];
     979           0 :         if (dist == 0) {
     980           0 :             send_code(s, lc, ltree); /* send a literal byte */
     981             :             Tracecv(isgraph(lc), (stderr," '%c' ", lc));
     982             :         } else {
     983             :             /* Here, lc is the match length - MIN_MATCH */
     984           0 :             code = length_code[lc];
     985           0 :             send_code(s, code+LITERALS+1, ltree); /* send the length code */
     986           0 :             extra = extra_lbits[code];
     987           0 :             if (extra != 0) {
     988           0 :                 lc -= base_length[code];
     989           0 :                 send_bits(s, lc, extra);       /* send the extra length bits */
     990             :             }
     991           0 :             dist--; /* dist is now the match distance - 1 */
     992           0 :             code = d_code(dist);
     993           0 :             Assert (code < D_CODES, "bad d_code");
     994             : 
     995           0 :             send_code(s, code, dtree);       /* send the distance code */
     996           0 :             extra = extra_dbits[code];
     997           0 :             if (extra != 0) {
     998           0 :                 dist -= base_dist[code];
     999           0 :                 send_bits(s, dist, extra);   /* send the extra distance bits */
    1000             :             }
    1001             :         } /* literal or match pair ? */
    1002             : 
    1003             :         /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
    1004           0 :         Assert(s->pending < s->lit_bufsize + 2*lx, "pendingBuf overflow");
    1005             : 
    1006           0 :     } while (lx < s->last_lit);
    1007             : 
    1008           0 :     send_code(s, END_BLOCK, ltree);
    1009           0 :     s->last_eob_len = ltree[END_BLOCK].Len;
    1010           0 : }
    1011             : 
    1012             : /* ===========================================================================
    1013             :  * Set the data type to ASCII or BINARY, using a crude approximation:
    1014             :  * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
    1015             :  * IN assertion: the fields freq of dyn_ltree are set and the total of all
    1016             :  * frequencies does not exceed 64K (to fit in an int on 16 bit machines).
    1017             :  */
    1018           0 : static void set_data_type(
    1019             :         deflate_state *s
    1020             : )
    1021             : {
    1022           0 :     int n = 0;
    1023           0 :     unsigned ascii_freq = 0;
    1024           0 :     unsigned bin_freq = 0;
    1025           0 :     while (n < 7)        bin_freq += s->dyn_ltree[n++].Freq;
    1026           0 :     while (n < 128)    ascii_freq += s->dyn_ltree[n++].Freq;
    1027           0 :     while (n < LITERALS) bin_freq += s->dyn_ltree[n++].Freq;
    1028           0 :     s->data_type = (Byte)(bin_freq > (ascii_freq >> 2) ? Z_BINARY : Z_ASCII);
    1029           0 : }
    1030             : 
    1031             : /* ===========================================================================
    1032             :  * Copy a stored block, storing first the length and its
    1033             :  * one's complement if requested.
    1034             :  */
    1035           0 : static void copy_block(
    1036             :         deflate_state *s,
    1037             :         char    *buf,     /* the input data */
    1038             :         unsigned len,     /* its length */
    1039             :         int      header   /* true if block header must be written */
    1040             : )
    1041             : {
    1042           0 :     bi_windup(s);        /* align on byte boundary */
    1043           0 :     s->last_eob_len = 8; /* enough lookahead for inflate */
    1044             : 
    1045           0 :     if (header) {
    1046           0 :         put_short(s, (ush)len);   
    1047           0 :         put_short(s, (ush)~len);
    1048             : #ifdef DEBUG_ZLIB
    1049             :         s->bits_sent += 2*16;
    1050             : #endif
    1051             :     }
    1052             : #ifdef DEBUG_ZLIB
    1053             :     s->bits_sent += (ulg)len<<3;
    1054             : #endif
    1055             :     /* bundle up the put_byte(s, *buf++) calls */
    1056           0 :     memcpy(&s->pending_buf[s->pending], buf, len);
    1057           0 :     s->pending += len;
    1058           0 : }
    1059             : 

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