trees.c

00001 /* trees.c -- output deflated data using Huffman coding
00002  * Copyright (C) 1995-2012 Jean-loup Gailly
00003  * detect_data_type() function provided freely by Cosmin Truta, 2006
00004  * For conditions of distribution and use, see copyright notice in zlib.h
00005  */
00006 
00007 /*
00008  *  ALGORITHM
00009  *
00010  *      The "deflation" process uses several Huffman trees. The more
00011  *      common source values are represented by shorter bit sequences.
00012  *
00013  *      Each code tree is stored in a compressed form which is itself
00014  * a Huffman encoding of the lengths of all the code strings (in
00015  * ascending order by source values).  The actual code strings are
00016  * reconstructed from the lengths in the inflate process, as described
00017  * in the deflate specification.
00018  *
00019  *  REFERENCES
00020  *
00021  *      Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
00022  *      Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
00023  *
00024  *      Storer, James A.
00025  *          Data Compression:  Methods and Theory, pp. 49-50.
00026  *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
00027  *
00028  *      Sedgewick, R.
00029  *          Algorithms, p290.
00030  *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
00031  */
00032 
00033 /* @(#) $Id$ */
00034 
00035 /* #define GEN_TREES_H */
00036 
00037 #include "deflate.h"
00038 
00039 #ifdef DEBUG
00040 #  include <ctype.h>
00041 #endif
00042 
00043 /* ===========================================================================
00044  * Constants
00045  */
00046 
00047 #define MAX_BL_BITS 7
00048 /* Bit length codes must not exceed MAX_BL_BITS bits */
00049 
00050 #define END_BLOCK 256
00051 /* end of block literal code */
00052 
00053 #define REP_3_6      16
00054 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
00055 
00056 #define REPZ_3_10    17
00057 /* repeat a zero length 3-10 times  (3 bits of repeat count) */
00058 
00059 #define REPZ_11_138  18
00060 /* repeat a zero length 11-138 times  (7 bits of repeat count) */
00061 
00062 local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
00063    = {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};
00064 
00065 local const int extra_dbits[D_CODES] /* extra bits for each distance code */
00066    = {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};
00067 
00068 local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
00069    = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
00070 
00071 local const uch bl_order[BL_CODES]
00072    = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
00073 /* The lengths of the bit length codes are sent in order of decreasing
00074  * probability, to avoid transmitting the lengths for unused bit length codes.
00075  */
00076 
00077 /* ===========================================================================
00078  * Local data. These are initialized only once.
00079  */
00080 
00081 #define DIST_CODE_LEN  512 /* see definition of array dist_code below */
00082 
00083 #if defined(GEN_TREES_H) || !defined(STDC)
00084 /* non ANSI compilers may not accept trees.h */
00085 
00086 local ct_data static_ltree[L_CODES+2];
00087 /* The static literal tree. Since the bit lengths are imposed, there is no
00088  * need for the L_CODES extra codes used during heap construction. However
00089  * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
00090  * below).
00091  */
00092 
00093 local ct_data static_dtree[D_CODES];
00094 /* The static distance tree. (Actually a trivial tree since all codes use
00095  * 5 bits.)
00096  */
00097 
00098 uch _dist_code[DIST_CODE_LEN];
00099 /* Distance codes. The first 256 values correspond to the distances
00100  * 3 .. 258, the last 256 values correspond to the top 8 bits of
00101  * the 15 bit distances.
00102  */
00103 
00104 uch _length_code[MAX_MATCH-MIN_MATCH+1];
00105 /* length code for each normalized match length (0 == MIN_MATCH) */
00106 
00107 local int base_length[LENGTH_CODES];
00108 /* First normalized length for each code (0 = MIN_MATCH) */
00109 
00110 local int base_dist[D_CODES];
00111 /* First normalized distance for each code (0 = distance of 1) */
00112 
00113 #else
00114 #  include "trees.h"
00115 #endif /* GEN_TREES_H */
00116 
00117 struct static_tree_desc_s {
00118     const ct_data *static_tree;  /* static tree or NULL */
00119     const intf *extra_bits;      /* extra bits for each code or NULL */
00120     int     extra_base;          /* base index for extra_bits */
00121     int     elems;               /* max number of elements in the tree */
00122     int     max_length;          /* max bit length for the codes */
00123 };
00124 
00125 local static_tree_desc  static_l_desc =
00126 {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
00127 
00128 local static_tree_desc  static_d_desc =
00129 {static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};
00130 
00131 local static_tree_desc  static_bl_desc =
00132 {(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
00133 
00134 /* ===========================================================================
00135  * Local (static) routines in this file.
00136  */
00137 
00138 local void tr_static_init OF((void));
00139 local void init_block     OF((deflate_state *s));
00140 local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));
00141 local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));
00142 local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));
00143 local void build_tree     OF((deflate_state *s, tree_desc *desc));
00144 local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));
00145 local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));
00146 local int  build_bl_tree  OF((deflate_state *s));
00147 local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
00148                               int blcodes));
00149 local void compress_block OF((deflate_state *s, ct_data *ltree,
00150                               ct_data *dtree));
00151 local int  detect_data_type OF((deflate_state *s));
00152 local unsigned bi_reverse OF((unsigned value, int length));
00153 local void bi_windup      OF((deflate_state *s));
00154 local void bi_flush       OF((deflate_state *s));
00155 local void copy_block     OF((deflate_state *s, charf *buf, unsigned len,
00156                               int header));
00157 
00158 #ifdef GEN_TREES_H
00159 local void gen_trees_header OF((void));
00160 #endif
00161 
00162 #ifndef DEBUG
00163 #  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
00164    /* Send a code of the given tree. c and tree must not have side effects */
00165 
00166 #else /* DEBUG */
00167 #  define send_code(s, c, tree) \
00168      { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
00169        send_bits(s, tree[c].Code, tree[c].Len); }
00170 #endif
00171 
00172 /* ===========================================================================
00173  * Output a short LSB first on the stream.
00174  * IN assertion: there is enough room in pendingBuf.
00175  */
00176 #define put_short(s, w) { \
00177     put_byte(s, (uch)((w) & 0xff)); \
00178     put_byte(s, (uch)((ush)(w) >> 8)); \
00179 }
00180 
00181 /* ===========================================================================
00182  * Send a value on a given number of bits.
00183  * IN assertion: length <= 16 and value fits in length bits.
00184  */
00185 #ifdef DEBUG
00186 local void send_bits      OF((deflate_state *s, int value, int length));
00187 
00188 local void send_bits(s, value, length)
00189     deflate_state *s;
00190     int value;  /* value to send */
00191     int length; /* number of bits */
00192 {
00193     Tracevv((stderr," l %2d v %4x ", length, value));
00194     Assert(length > 0 && length <= 15, "invalid length");
00195     s->bits_sent += (ulg)length;
00196 
00197     /* If not enough room in bi_buf, use (valid) bits from bi_buf and
00198      * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
00199      * unused bits in value.
00200      */
00201     if (s->bi_valid > (int)Buf_size - length) {
00202         s->bi_buf |= (ush)value << s->bi_valid;
00203         put_short(s, s->bi_buf);
00204         s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
00205         s->bi_valid += length - Buf_size;
00206     } else {
00207         s->bi_buf |= (ush)value << s->bi_valid;
00208         s->bi_valid += length;
00209     }
00210 }
00211 #else /* !DEBUG */
00212 
00213 #define send_bits(s, value, length) \
00214 { int len = length;\
00215   if (s->bi_valid > (int)Buf_size - len) {\
00216     int val = value;\
00217     s->bi_buf |= (ush)val << s->bi_valid;\
00218     put_short(s, s->bi_buf);\
00219     s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
00220     s->bi_valid += len - Buf_size;\
00221   } else {\
00222     s->bi_buf |= (ush)(value) << s->bi_valid;\
00223     s->bi_valid += len;\
00224   }\
00225 }
00226 #endif /* DEBUG */
00227 
00228 
00229 /* the arguments must not have side effects */
00230 
00231 /* ===========================================================================
00232  * Initialize the various 'constant' tables.
00233  */
00234 local void tr_static_init()
00235 {
00236 #if defined(GEN_TREES_H) || !defined(STDC)
00237     static int static_init_done = 0;
00238     int n;        /* iterates over tree elements */
00239     int bits;     /* bit counter */
00240     int length;   /* length value */
00241     int code;     /* code value */
00242     int dist;     /* distance index */
00243     ush bl_count[MAX_BITS+1];
00244     /* number of codes at each bit length for an optimal tree */
00245 
00246     if (static_init_done) return;
00247 
00248     /* For some embedded targets, global variables are not initialized: */
00249 #ifdef NO_INIT_GLOBAL_POINTERS
00250     static_l_desc.static_tree = static_ltree;
00251     static_l_desc.extra_bits = extra_lbits;
00252     static_d_desc.static_tree = static_dtree;
00253     static_d_desc.extra_bits = extra_dbits;
00254     static_bl_desc.extra_bits = extra_blbits;
00255 #endif
00256 
00257     /* Initialize the mapping length (0..255) -> length code (0..28) */
00258     length = 0;
00259     for (code = 0; code < LENGTH_CODES-1; code++) {
00260         base_length[code] = length;
00261         for (n = 0; n < (1<<extra_lbits[code]); n++) {
00262             _length_code[length++] = (uch)code;
00263         }
00264     }
00265     Assert (length == 256, "tr_static_init: length != 256");
00266     /* Note that the length 255 (match length 258) can be represented
00267      * in two different ways: code 284 + 5 bits or code 285, so we
00268      * overwrite length_code[255] to use the best encoding:
00269      */
00270     _length_code[length-1] = (uch)code;
00271 
00272     /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
00273     dist = 0;
00274     for (code = 0 ; code < 16; code++) {
00275         base_dist[code] = dist;
00276         for (n = 0; n < (1<<extra_dbits[code]); n++) {
00277             _dist_code[dist++] = (uch)code;
00278         }
00279     }
00280     Assert (dist == 256, "tr_static_init: dist != 256");
00281     dist >>= 7; /* from now on, all distances are divided by 128 */
00282     for ( ; code < D_CODES; code++) {
00283         base_dist[code] = dist << 7;
00284         for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
00285             _dist_code[256 + dist++] = (uch)code;
00286         }
00287     }
00288     Assert (dist == 256, "tr_static_init: 256+dist != 512");
00289 
00290     /* Construct the codes of the static literal tree */
00291     for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
00292     n = 0;
00293     while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
00294     while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
00295     while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
00296     while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
00297     /* Codes 286 and 287 do not exist, but we must include them in the
00298      * tree construction to get a canonical Huffman tree (longest code
00299      * all ones)
00300      */
00301     gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
00302 
00303     /* The static distance tree is trivial: */
00304     for (n = 0; n < D_CODES; n++) {
00305         static_dtree[n].Len = 5;
00306         static_dtree[n].Code = bi_reverse((unsigned)n, 5);
00307     }
00308     static_init_done = 1;
00309 
00310 #  ifdef GEN_TREES_H
00311     gen_trees_header();
00312 #  endif
00313 #endif /* defined(GEN_TREES_H) || !defined(STDC) */
00314 }
00315 
00316 /* ===========================================================================
00317  * Genererate the file trees.h describing the static trees.
00318  */
00319 #ifdef GEN_TREES_H
00320 #  ifndef DEBUG
00321 #    include <stdio.h>
00322 #  endif
00323 
00324 #  define SEPARATOR(i, last, width) \
00325       ((i) == (last)? "\n};\n\n" :    \
00326        ((i) % (width) == (width)-1 ? ",\n" : ", "))
00327 
00328 void gen_trees_header()
00329 {
00330     FILE *header = fopen("trees.h", "w");
00331     int i;
00332 
00333     Assert (header != NULL, "Can't open trees.h");
00334     fprintf(header,
00335             "/* header created automatically with -DGEN_TREES_H */\n\n");
00336 
00337     fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
00338     for (i = 0; i < L_CODES+2; i++) {
00339         fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
00340                 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
00341     }
00342 
00343     fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
00344     for (i = 0; i < D_CODES; i++) {
00345         fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
00346                 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
00347     }
00348 
00349     fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
00350     for (i = 0; i < DIST_CODE_LEN; i++) {
00351         fprintf(header, "%2u%s", _dist_code[i],
00352                 SEPARATOR(i, DIST_CODE_LEN-1, 20));
00353     }
00354 
00355     fprintf(header,
00356         "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
00357     for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
00358         fprintf(header, "%2u%s", _length_code[i],
00359                 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
00360     }
00361 
00362     fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
00363     for (i = 0; i < LENGTH_CODES; i++) {
00364         fprintf(header, "%1u%s", base_length[i],
00365                 SEPARATOR(i, LENGTH_CODES-1, 20));
00366     }
00367 
00368     fprintf(header, "local const int base_dist[D_CODES] = {\n");
00369     for (i = 0; i < D_CODES; i++) {
00370         fprintf(header, "%5u%s", base_dist[i],
00371                 SEPARATOR(i, D_CODES-1, 10));
00372     }
00373 
00374     fclose(header);
00375 }
00376 #endif /* GEN_TREES_H */
00377 
00378 /* ===========================================================================
00379  * Initialize the tree data structures for a new zlib stream.
00380  */
00381 void ZLIB_INTERNAL _tr_init(s)
00382     deflate_state *s;
00383 {
00384     tr_static_init();
00385 
00386     s->l_desc.dyn_tree = s->dyn_ltree;
00387     s->l_desc.stat_desc = &static_l_desc;
00388 
00389     s->d_desc.dyn_tree = s->dyn_dtree;
00390     s->d_desc.stat_desc = &static_d_desc;
00391 
00392     s->bl_desc.dyn_tree = s->bl_tree;
00393     s->bl_desc.stat_desc = &static_bl_desc;
00394 
00395     s->bi_buf = 0;
00396     s->bi_valid = 0;
00397 #ifdef DEBUG
00398     s->compressed_len = 0L;
00399     s->bits_sent = 0L;
00400 #endif
00401 
00402     /* Initialize the first block of the first file: */
00403     init_block(s);
00404 }
00405 
00406 /* ===========================================================================
00407  * Initialize a new block.
00408  */
00409 local void init_block(s)
00410     deflate_state *s;
00411 {
00412     int n; /* iterates over tree elements */
00413 
00414     /* Initialize the trees. */
00415     for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
00416     for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
00417     for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
00418 
00419     s->dyn_ltree[END_BLOCK].Freq = 1;
00420     s->opt_len = s->static_len = 0L;
00421     s->last_lit = s->matches = 0;
00422 }
00423 
00424 #define SMALLEST 1
00425 /* Index within the heap array of least frequent node in the Huffman tree */
00426 
00427 
00428 /* ===========================================================================
00429  * Remove the smallest element from the heap and recreate the heap with
00430  * one less element. Updates heap and heap_len.
00431  */
00432 #define pqremove(s, tree, top) \
00433 {\
00434     top = s->heap[SMALLEST]; \
00435     s->heap[SMALLEST] = s->heap[s->heap_len--]; \
00436     pqdownheap(s, tree, SMALLEST); \
00437 }
00438 
00439 /* ===========================================================================
00440  * Compares to subtrees, using the tree depth as tie breaker when
00441  * the subtrees have equal frequency. This minimizes the worst case length.
00442  */
00443 #define smaller(tree, n, m, depth) \
00444    (tree[n].Freq < tree[m].Freq || \
00445    (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
00446 
00447 /* ===========================================================================
00448  * Restore the heap property by moving down the tree starting at node k,
00449  * exchanging a node with the smallest of its two sons if necessary, stopping
00450  * when the heap property is re-established (each father smaller than its
00451  * two sons).
00452  */
00453 local void pqdownheap(s, tree, k)
00454     deflate_state *s;
00455     ct_data *tree;  /* the tree to restore */
00456     int k;               /* node to move down */
00457 {
00458     int v = s->heap[k];
00459     int j = k << 1;  /* left son of k */
00460     while (j <= s->heap_len) {
00461         /* Set j to the smallest of the two sons: */
00462         if (j < s->heap_len &&
00463             smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
00464             j++;
00465         }
00466         /* Exit if v is smaller than both sons */
00467         if (smaller(tree, v, s->heap[j], s->depth)) break;
00468 
00469         /* Exchange v with the smallest son */
00470         s->heap[k] = s->heap[j];  k = j;
00471 
00472         /* And continue down the tree, setting j to the left son of k */
00473         j <<= 1;
00474     }
00475     s->heap[k] = v;
00476 }
00477 
00478 /* ===========================================================================
00479  * Compute the optimal bit lengths for a tree and update the total bit length
00480  * for the current block.
00481  * IN assertion: the fields freq and dad are set, heap[heap_max] and
00482  *    above are the tree nodes sorted by increasing frequency.
00483  * OUT assertions: the field len is set to the optimal bit length, the
00484  *     array bl_count contains the frequencies for each bit length.
00485  *     The length opt_len is updated; static_len is also updated if stree is
00486  *     not null.
00487  */
00488 local void gen_bitlen(s, desc)
00489     deflate_state *s;
00490     tree_desc *desc;    /* the tree descriptor */
00491 {
00492     ct_data *tree        = desc->dyn_tree;
00493     int max_code         = desc->max_code;
00494     const ct_data *stree = desc->stat_desc->static_tree;
00495     const intf *extra    = desc->stat_desc->extra_bits;
00496     int base             = desc->stat_desc->extra_base;
00497     int max_length       = desc->stat_desc->max_length;
00498     int h;              /* heap index */
00499     int n, m;           /* iterate over the tree elements */
00500     int bits;           /* bit length */
00501     int xbits;          /* extra bits */
00502     ush f;              /* frequency */
00503     int overflow = 0;   /* number of elements with bit length too large */
00504 
00505     for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
00506 
00507     /* In a first pass, compute the optimal bit lengths (which may
00508      * overflow in the case of the bit length tree).
00509      */
00510     tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
00511 
00512     for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
00513         n = s->heap[h];
00514         bits = tree[tree[n].Dad].Len + 1;
00515         if (bits > max_length) bits = max_length, overflow++;
00516         tree[n].Len = (ush)bits;
00517         /* We overwrite tree[n].Dad which is no longer needed */
00518 
00519         if (n > max_code) continue; /* not a leaf node */
00520 
00521         s->bl_count[bits]++;
00522         xbits = 0;
00523         if (n >= base) xbits = extra[n-base];
00524         f = tree[n].Freq;
00525         s->opt_len += (ulg)f * (bits + xbits);
00526         if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
00527     }
00528     if (overflow == 0) return;
00529 
00530     Trace((stderr,"\nbit length overflow\n"));
00531     /* This happens for example on obj2 and pic of the Calgary corpus */
00532 
00533     /* Find the first bit length which could increase: */
00534     do {
00535         bits = max_length-1;
00536         while (s->bl_count[bits] == 0) bits--;
00537         s->bl_count[bits]--;      /* move one leaf down the tree */
00538         s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
00539         s->bl_count[max_length]--;
00540         /* The brother of the overflow item also moves one step up,
00541          * but this does not affect bl_count[max_length]
00542          */
00543         overflow -= 2;
00544     } while (overflow > 0);
00545 
00546     /* Now recompute all bit lengths, scanning in increasing frequency.
00547      * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
00548      * lengths instead of fixing only the wrong ones. This idea is taken
00549      * from 'ar' written by Haruhiko Okumura.)
00550      */
00551     for (bits = max_length; bits != 0; bits--) {
00552         n = s->bl_count[bits];
00553         while (n != 0) {
00554             m = s->heap[--h];
00555             if (m > max_code) continue;
00556             if ((unsigned) tree[m].Len != (unsigned) bits) {
00557                 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
00558                 s->opt_len += ((long)bits - (long)tree[m].Len)
00559                               *(long)tree[m].Freq;
00560                 tree[m].Len = (ush)bits;
00561             }
00562             n--;
00563         }
00564     }
00565 }
00566 
00567 /* ===========================================================================
00568  * Generate the codes for a given tree and bit counts (which need not be
00569  * optimal).
00570  * IN assertion: the array bl_count contains the bit length statistics for
00571  * the given tree and the field len is set for all tree elements.
00572  * OUT assertion: the field code is set for all tree elements of non
00573  *     zero code length.
00574  */
00575 local void gen_codes (tree, max_code, bl_count)
00576     ct_data *tree;             /* the tree to decorate */
00577     int max_code;              /* largest code with non zero frequency */
00578     ushf *bl_count;            /* number of codes at each bit length */
00579 {
00580     ush next_code[MAX_BITS+1]; /* next code value for each bit length */
00581     ush code = 0;              /* running code value */
00582     int bits;                  /* bit index */
00583     int n;                     /* code index */
00584 
00585     /* The distribution counts are first used to generate the code values
00586      * without bit reversal.
00587      */
00588     for (bits = 1; bits <= MAX_BITS; bits++) {
00589         next_code[bits] = code = (code + bl_count[bits-1]) << 1;
00590     }
00591     /* Check that the bit counts in bl_count are consistent. The last code
00592      * must be all ones.
00593      */
00594     Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
00595             "inconsistent bit counts");
00596     Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
00597 
00598     for (n = 0;  n <= max_code; n++) {
00599         int len = tree[n].Len;
00600         if (len == 0) continue;
00601         /* Now reverse the bits */
00602         tree[n].Code = bi_reverse(next_code[len]++, len);
00603 
00604         Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
00605              n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
00606     }
00607 }
00608 
00609 /* ===========================================================================
00610  * Construct one Huffman tree and assigns the code bit strings and lengths.
00611  * Update the total bit length for the current block.
00612  * IN assertion: the field freq is set for all tree elements.
00613  * OUT assertions: the fields len and code are set to the optimal bit length
00614  *     and corresponding code. The length opt_len is updated; static_len is
00615  *     also updated if stree is not null. The field max_code is set.
00616  */
00617 local void build_tree(s, desc)
00618     deflate_state *s;
00619     tree_desc *desc; /* the tree descriptor */
00620 {
00621     ct_data *tree         = desc->dyn_tree;
00622     const ct_data *stree  = desc->stat_desc->static_tree;
00623     int elems             = desc->stat_desc->elems;
00624     int n, m;          /* iterate over heap elements */
00625     int max_code = -1; /* largest code with non zero frequency */
00626     int node;          /* new node being created */
00627 
00628     /* Construct the initial heap, with least frequent element in
00629      * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
00630      * heap[0] is not used.
00631      */
00632     s->heap_len = 0, s->heap_max = HEAP_SIZE;
00633 
00634     for (n = 0; n < elems; n++) {
00635         if (tree[n].Freq != 0) {
00636             s->heap[++(s->heap_len)] = max_code = n;
00637             s->depth[n] = 0;
00638         } else {
00639             tree[n].Len = 0;
00640         }
00641     }
00642 
00643     /* The pkzip format requires that at least one distance code exists,
00644      * and that at least one bit should be sent even if there is only one
00645      * possible code. So to avoid special checks later on we force at least
00646      * two codes of non zero frequency.
00647      */
00648     while (s->heap_len < 2) {
00649         node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
00650         tree[node].Freq = 1;
00651         s->depth[node] = 0;
00652         s->opt_len--; if (stree) s->static_len -= stree[node].Len;
00653         /* node is 0 or 1 so it does not have extra bits */
00654     }
00655     desc->max_code = max_code;
00656 
00657     /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
00658      * establish sub-heaps of increasing lengths:
00659      */
00660     for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
00661 
00662     /* Construct the Huffman tree by repeatedly combining the least two
00663      * frequent nodes.
00664      */
00665     node = elems;              /* next internal node of the tree */
00666     do {
00667         pqremove(s, tree, n);  /* n = node of least frequency */
00668         m = s->heap[SMALLEST]; /* m = node of next least frequency */
00669 
00670         s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
00671         s->heap[--(s->heap_max)] = m;
00672 
00673         /* Create a new node father of n and m */
00674         tree[node].Freq = tree[n].Freq + tree[m].Freq;
00675         s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
00676                                 s->depth[n] : s->depth[m]) + 1);
00677         tree[n].Dad = tree[m].Dad = (ush)node;
00678 #ifdef DUMP_BL_TREE
00679         if (tree == s->bl_tree) {
00680             fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
00681                     node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
00682         }
00683 #endif
00684         /* and insert the new node in the heap */
00685         s->heap[SMALLEST] = node++;
00686         pqdownheap(s, tree, SMALLEST);
00687 
00688     } while (s->heap_len >= 2);
00689 
00690     s->heap[--(s->heap_max)] = s->heap[SMALLEST];
00691 
00692     /* At this point, the fields freq and dad are set. We can now
00693      * generate the bit lengths.
00694      */
00695     gen_bitlen(s, (tree_desc *)desc);
00696 
00697     /* The field len is now set, we can generate the bit codes */
00698     gen_codes ((ct_data *)tree, max_code, s->bl_count);
00699 }
00700 
00701 /* ===========================================================================
00702  * Scan a literal or distance tree to determine the frequencies of the codes
00703  * in the bit length tree.
00704  */
00705 local void scan_tree (s, tree, max_code)
00706     deflate_state *s;
00707     ct_data *tree;   /* the tree to be scanned */
00708     int max_code;    /* and its largest code of non zero frequency */
00709 {
00710     int n;                     /* iterates over all tree elements */
00711     int prevlen = -1;          /* last emitted length */
00712     int curlen;                /* length of current code */
00713     int nextlen = tree[0].Len; /* length of next code */
00714     int count = 0;             /* repeat count of the current code */
00715     int max_count = 7;         /* max repeat count */
00716     int min_count = 4;         /* min repeat count */
00717 
00718     if (nextlen == 0) max_count = 138, min_count = 3;
00719     tree[max_code+1].Len = (ush)0xffff; /* guard */
00720 
00721     for (n = 0; n <= max_code; n++) {
00722         curlen = nextlen; nextlen = tree[n+1].Len;
00723         if (++count < max_count && curlen == nextlen) {
00724             continue;
00725         } else if (count < min_count) {
00726             s->bl_tree[curlen].Freq += count;
00727         } else if (curlen != 0) {
00728             if (curlen != prevlen) s->bl_tree[curlen].Freq++;
00729             s->bl_tree[REP_3_6].Freq++;
00730         } else if (count <= 10) {
00731             s->bl_tree[REPZ_3_10].Freq++;
00732         } else {
00733             s->bl_tree[REPZ_11_138].Freq++;
00734         }
00735         count = 0; prevlen = curlen;
00736         if (nextlen == 0) {
00737             max_count = 138, min_count = 3;
00738         } else if (curlen == nextlen) {
00739             max_count = 6, min_count = 3;
00740         } else {
00741             max_count = 7, min_count = 4;
00742         }
00743     }
00744 }
00745 
00746 /* ===========================================================================
00747  * Send a literal or distance tree in compressed form, using the codes in
00748  * bl_tree.
00749  */
00750 local void send_tree (s, tree, max_code)
00751     deflate_state *s;
00752     ct_data *tree; /* the tree to be scanned */
00753     int max_code;       /* and its largest code of non zero frequency */
00754 {
00755     int n;                     /* iterates over all tree elements */
00756     int prevlen = -1;          /* last emitted length */
00757     int curlen;                /* length of current code */
00758     int nextlen = tree[0].Len; /* length of next code */
00759     int count = 0;             /* repeat count of the current code */
00760     int max_count = 7;         /* max repeat count */
00761     int min_count = 4;         /* min repeat count */
00762 
00763     /* tree[max_code+1].Len = -1; */  /* guard already set */
00764     if (nextlen == 0) max_count = 138, min_count = 3;
00765 
00766     for (n = 0; n <= max_code; n++) {
00767         curlen = nextlen; nextlen = tree[n+1].Len;
00768         if (++count < max_count && curlen == nextlen) {
00769             continue;
00770         } else if (count < min_count) {
00771             do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
00772 
00773         } else if (curlen != 0) {
00774             if (curlen != prevlen) {
00775                 send_code(s, curlen, s->bl_tree); count--;
00776             }
00777             Assert(count >= 3 && count <= 6, " 3_6?");
00778             send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
00779 
00780         } else if (count <= 10) {
00781             send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
00782 
00783         } else {
00784             send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
00785         }
00786         count = 0; prevlen = curlen;
00787         if (nextlen == 0) {
00788             max_count = 138, min_count = 3;
00789         } else if (curlen == nextlen) {
00790             max_count = 6, min_count = 3;
00791         } else {
00792             max_count = 7, min_count = 4;
00793         }
00794     }
00795 }
00796 
00797 /* ===========================================================================
00798  * Construct the Huffman tree for the bit lengths and return the index in
00799  * bl_order of the last bit length code to send.
00800  */
00801 local int build_bl_tree(s)
00802     deflate_state *s;
00803 {
00804     int max_blindex;  /* index of last bit length code of non zero freq */
00805 
00806     /* Determine the bit length frequencies for literal and distance trees */
00807     scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
00808     scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
00809 
00810     /* Build the bit length tree: */
00811     build_tree(s, (tree_desc *)(&(s->bl_desc)));
00812     /* opt_len now includes the length of the tree representations, except
00813      * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
00814      */
00815 
00816     /* Determine the number of bit length codes to send. The pkzip format
00817      * requires that at least 4 bit length codes be sent. (appnote.txt says
00818      * 3 but the actual value used is 4.)
00819      */
00820     for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
00821         if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
00822     }
00823     /* Update opt_len to include the bit length tree and counts */
00824     s->opt_len += 3*(max_blindex+1) + 5+5+4;
00825     Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
00826             s->opt_len, s->static_len));
00827 
00828     return max_blindex;
00829 }
00830 
00831 /* ===========================================================================
00832  * Send the header for a block using dynamic Huffman trees: the counts, the
00833  * lengths of the bit length codes, the literal tree and the distance tree.
00834  * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
00835  */
00836 local void send_all_trees(s, lcodes, dcodes, blcodes)
00837     deflate_state *s;
00838     int lcodes, dcodes, blcodes; /* number of codes for each tree */
00839 {
00840     int rank;                    /* index in bl_order */
00841 
00842     Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
00843     Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
00844             "too many codes");
00845     Tracev((stderr, "\nbl counts: "));
00846     send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
00847     send_bits(s, dcodes-1,   5);
00848     send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
00849     for (rank = 0; rank < blcodes; rank++) {
00850         Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
00851         send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
00852     }
00853     Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
00854 
00855     send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
00856     Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
00857 
00858     send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
00859     Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
00860 }
00861 
00862 /* ===========================================================================
00863  * Send a stored block
00864  */
00865 void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
00866     deflate_state *s;
00867     charf *buf;       /* input block */
00868     ulg stored_len;   /* length of input block */
00869     int last;         /* one if this is the last block for a file */
00870 {
00871     send_bits(s, (STORED_BLOCK<<1)+last, 3);    /* send block type */
00872 #ifdef DEBUG
00873     s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
00874     s->compressed_len += (stored_len + 4) << 3;
00875 #endif
00876     copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
00877 }
00878 
00879 /* ===========================================================================
00880  * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
00881  */
00882 void ZLIB_INTERNAL _tr_flush_bits(s)
00883     deflate_state *s;
00884 {
00885     bi_flush(s);
00886 }
00887 
00888 /* ===========================================================================
00889  * Send one empty static block to give enough lookahead for inflate.
00890  * This takes 10 bits, of which 7 may remain in the bit buffer.
00891  */
00892 void ZLIB_INTERNAL _tr_align(s)
00893     deflate_state *s;
00894 {
00895     send_bits(s, STATIC_TREES<<1, 3);
00896     send_code(s, END_BLOCK, static_ltree);
00897 #ifdef DEBUG
00898     s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
00899 #endif
00900     bi_flush(s);
00901 }
00902 
00903 /* ===========================================================================
00904  * Determine the best encoding for the current block: dynamic trees, static
00905  * trees or store, and output the encoded block to the zip file.
00906  */
00907 void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
00908     deflate_state *s;
00909     charf *buf;       /* input block, or NULL if too old */
00910     ulg stored_len;   /* length of input block */
00911     int last;         /* one if this is the last block for a file */
00912 {
00913     ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
00914     int max_blindex = 0;  /* index of last bit length code of non zero freq */
00915 
00916     /* Build the Huffman trees unless a stored block is forced */
00917     if (s->level > 0) {
00918 
00919         /* Check if the file is binary or text */
00920         if (s->strm->data_type == Z_UNKNOWN)
00921             s->strm->data_type = detect_data_type(s);
00922 
00923         /* Construct the literal and distance trees */
00924         build_tree(s, (tree_desc *)(&(s->l_desc)));
00925         Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
00926                 s->static_len));
00927 
00928         build_tree(s, (tree_desc *)(&(s->d_desc)));
00929         Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
00930                 s->static_len));
00931         /* At this point, opt_len and static_len are the total bit lengths of
00932          * the compressed block data, excluding the tree representations.
00933          */
00934 
00935         /* Build the bit length tree for the above two trees, and get the index
00936          * in bl_order of the last bit length code to send.
00937          */
00938         max_blindex = build_bl_tree(s);
00939 
00940         /* Determine the best encoding. Compute the block lengths in bytes. */
00941         opt_lenb = (s->opt_len+3+7)>>3;
00942         static_lenb = (s->static_len+3+7)>>3;
00943 
00944         Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
00945                 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
00946                 s->last_lit));
00947 
00948         if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
00949 
00950     } else {
00951         Assert(buf != (char*)0, "lost buf");
00952         opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
00953     }
00954 
00955 #ifdef FORCE_STORED
00956     if (buf != (char*)0) { /* force stored block */
00957 #else
00958     if (stored_len+4 <= opt_lenb && buf != (char*)0) {
00959                        /* 4: two words for the lengths */
00960 #endif
00961         /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
00962          * Otherwise we can't have processed more than WSIZE input bytes since
00963          * the last block flush, because compression would have been
00964          * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
00965          * transform a block into a stored block.
00966          */
00967         _tr_stored_block(s, buf, stored_len, last);
00968 
00969 #ifdef FORCE_STATIC
00970     } else if (static_lenb >= 0) { /* force static trees */
00971 #else
00972     } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
00973 #endif
00974         send_bits(s, (STATIC_TREES<<1)+last, 3);
00975         compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
00976 #ifdef DEBUG
00977         s->compressed_len += 3 + s->static_len;
00978 #endif
00979     } else {
00980         send_bits(s, (DYN_TREES<<1)+last, 3);
00981         send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
00982                        max_blindex+1);
00983         compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
00984 #ifdef DEBUG
00985         s->compressed_len += 3 + s->opt_len;
00986 #endif
00987     }
00988     Assert (s->compressed_len == s->bits_sent, "bad compressed size");
00989     /* The above check is made mod 2^32, for files larger than 512 MB
00990      * and uLong implemented on 32 bits.
00991      */
00992     init_block(s);
00993 
00994     if (last) {
00995         bi_windup(s);
00996 #ifdef DEBUG
00997         s->compressed_len += 7;  /* align on byte boundary */
00998 #endif
00999     }
01000     Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
01001            s->compressed_len-7*last));
01002 }
01003 
01004 /* ===========================================================================
01005  * Save the match info and tally the frequency counts. Return true if
01006  * the current block must be flushed.
01007  */
01008 int ZLIB_INTERNAL _tr_tally (s, dist, lc)
01009     deflate_state *s;
01010     unsigned dist;  /* distance of matched string */
01011     unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
01012 {
01013     s->d_buf[s->last_lit] = (ush)dist;
01014     s->l_buf[s->last_lit++] = (uch)lc;
01015     if (dist == 0) {
01016         /* lc is the unmatched char */
01017         s->dyn_ltree[lc].Freq++;
01018     } else {
01019         s->matches++;
01020         /* Here, lc is the match length - MIN_MATCH */
01021         dist--;             /* dist = match distance - 1 */
01022         Assert((ush)dist < (ush)MAX_DIST(s) &&
01023                (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
01024                (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
01025 
01026         s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
01027         s->dyn_dtree[d_code(dist)].Freq++;
01028     }
01029 
01030 #ifdef TRUNCATE_BLOCK
01031     /* Try to guess if it is profitable to stop the current block here */
01032     if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
01033         /* Compute an upper bound for the compressed length */
01034         ulg out_length = (ulg)s->last_lit*8L;
01035         ulg in_length = (ulg)((long)s->strstart - s->block_start);
01036         int dcode;
01037         for (dcode = 0; dcode < D_CODES; dcode++) {
01038             out_length += (ulg)s->dyn_dtree[dcode].Freq *
01039                 (5L+extra_dbits[dcode]);
01040         }
01041         out_length >>= 3;
01042         Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
01043                s->last_lit, in_length, out_length,
01044                100L - out_length*100L/in_length));
01045         if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
01046     }
01047 #endif
01048     return (s->last_lit == s->lit_bufsize-1);
01049     /* We avoid equality with lit_bufsize because of wraparound at 64K
01050      * on 16 bit machines and because stored blocks are restricted to
01051      * 64K-1 bytes.
01052      */
01053 }
01054 
01055 /* ===========================================================================
01056  * Send the block data compressed using the given Huffman trees
01057  */
01058 local void compress_block(s, ltree, dtree)
01059     deflate_state *s;
01060     ct_data *ltree; /* literal tree */
01061     ct_data *dtree; /* distance tree */
01062 {
01063     unsigned dist;      /* distance of matched string */
01064     int lc;             /* match length or unmatched char (if dist == 0) */
01065     unsigned lx = 0;    /* running index in l_buf */
01066     unsigned code;      /* the code to send */
01067     int extra;          /* number of extra bits to send */
01068 
01069     if (s->last_lit != 0) do {
01070         dist = s->d_buf[lx];
01071         lc = s->l_buf[lx++];
01072         if (dist == 0) {
01073             send_code(s, lc, ltree); /* send a literal byte */
01074             Tracecv(isgraph(lc), (stderr," '%c' ", lc));
01075         } else {
01076             /* Here, lc is the match length - MIN_MATCH */
01077             code = _length_code[lc];
01078             send_code(s, code+LITERALS+1, ltree); /* send the length code */
01079             extra = extra_lbits[code];
01080             if (extra != 0) {
01081                 lc -= base_length[code];
01082                 send_bits(s, lc, extra);       /* send the extra length bits */
01083             }
01084             dist--; /* dist is now the match distance - 1 */
01085             code = d_code(dist);
01086             Assert (code < D_CODES, "bad d_code");
01087 
01088             send_code(s, code, dtree);       /* send the distance code */
01089             extra = extra_dbits[code];
01090             if (extra != 0) {
01091                 dist -= base_dist[code];
01092                 send_bits(s, dist, extra);   /* send the extra distance bits */
01093             }
01094         } /* literal or match pair ? */
01095 
01096         /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
01097         Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
01098                "pendingBuf overflow");
01099 
01100     } while (lx < s->last_lit);
01101 
01102     send_code(s, END_BLOCK, ltree);
01103 }
01104 
01105 /* ===========================================================================
01106  * Check if the data type is TEXT or BINARY, using the following algorithm:
01107  * - TEXT if the two conditions below are satisfied:
01108  *    a) There are no non-portable control characters belonging to the
01109  *       "black list" (0..6, 14..25, 28..31).
01110  *    b) There is at least one printable character belonging to the
01111  *       "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
01112  * - BINARY otherwise.
01113  * - The following partially-portable control characters form a
01114  *   "gray list" that is ignored in this detection algorithm:
01115  *   (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
01116  * IN assertion: the fields Freq of dyn_ltree are set.
01117  */
01118 local int detect_data_type(s)
01119     deflate_state *s;
01120 {
01121     /* black_mask is the bit mask of black-listed bytes
01122      * set bits 0..6, 14..25, and 28..31
01123      * 0xf3ffc07f = binary 11110011111111111100000001111111
01124      */
01125     unsigned long black_mask = 0xf3ffc07fUL;
01126     int n;
01127 
01128     /* Check for non-textual ("black-listed") bytes. */
01129     for (n = 0; n <= 31; n++, black_mask >>= 1)
01130         if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
01131             return Z_BINARY;
01132 
01133     /* Check for textual ("white-listed") bytes. */
01134     if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
01135             || s->dyn_ltree[13].Freq != 0)
01136         return Z_TEXT;
01137     for (n = 32; n < LITERALS; n++)
01138         if (s->dyn_ltree[n].Freq != 0)
01139             return Z_TEXT;
01140 
01141     /* There are no "black-listed" or "white-listed" bytes:
01142      * this stream either is empty or has tolerated ("gray-listed") bytes only.
01143      */
01144     return Z_BINARY;
01145 }
01146 
01147 /* ===========================================================================
01148  * Reverse the first len bits of a code, using straightforward code (a faster
01149  * method would use a table)
01150  * IN assertion: 1 <= len <= 15
01151  */
01152 local unsigned bi_reverse(code, len)
01153     unsigned code; /* the value to invert */
01154     int len;       /* its bit length */
01155 {
01156     register unsigned res = 0;
01157     do {
01158         res |= code & 1;
01159         code >>= 1, res <<= 1;
01160     } while (--len > 0);
01161     return res >> 1;
01162 }
01163 
01164 /* ===========================================================================
01165  * Flush the bit buffer, keeping at most 7 bits in it.
01166  */
01167 local void bi_flush(s)
01168     deflate_state *s;
01169 {
01170     if (s->bi_valid == 16) {
01171         put_short(s, s->bi_buf);
01172         s->bi_buf = 0;
01173         s->bi_valid = 0;
01174     } else if (s->bi_valid >= 8) {
01175         put_byte(s, (Byte)s->bi_buf);
01176         s->bi_buf >>= 8;
01177         s->bi_valid -= 8;
01178     }
01179 }
01180 
01181 /* ===========================================================================
01182  * Flush the bit buffer and align the output on a byte boundary
01183  */
01184 local void bi_windup(s)
01185     deflate_state *s;
01186 {
01187     if (s->bi_valid > 8) {
01188         put_short(s, s->bi_buf);
01189     } else if (s->bi_valid > 0) {
01190         put_byte(s, (Byte)s->bi_buf);
01191     }
01192     s->bi_buf = 0;
01193     s->bi_valid = 0;
01194 #ifdef DEBUG
01195     s->bits_sent = (s->bits_sent+7) & ~7;
01196 #endif
01197 }
01198 
01199 /* ===========================================================================
01200  * Copy a stored block, storing first the length and its
01201  * one's complement if requested.
01202  */
01203 local void copy_block(s, buf, len, header)
01204     deflate_state *s;
01205     charf    *buf;    /* the input data */
01206     unsigned len;     /* its length */
01207     int      header;  /* true if block header must be written */
01208 {
01209     bi_windup(s);        /* align on byte boundary */
01210 
01211     if (header) {
01212         put_short(s, (ush)len);
01213         put_short(s, (ush)~len);
01214 #ifdef DEBUG
01215         s->bits_sent += 2*16;
01216 #endif
01217     }
01218 #ifdef DEBUG
01219     s->bits_sent += (ulg)len<<3;
01220 #endif
01221     while (len--) {
01222         put_byte(s, *buf++);
01223     }
01224 }