Annotation of embedaddon/sudo/zlib/trees.c, revision 1.1.1.2

1.1       misho       1: /* trees.c -- output deflated data using Huffman coding
1.1.1.2 ! misho       2:  * Copyright (C) 1995-2012 Jean-loup Gailly
1.1       misho       3:  * detect_data_type() function provided freely by Cosmin Truta, 2006
                      4:  * For conditions of distribution and use, see copyright notice in zlib.h
                      5:  */
                      6: 
                      7: /*
                      8:  *  ALGORITHM
                      9:  *
                     10:  *      The "deflation" process uses several Huffman trees. The more
                     11:  *      common source values are represented by shorter bit sequences.
                     12:  *
                     13:  *      Each code tree is stored in a compressed form which is itself
                     14:  * a Huffman encoding of the lengths of all the code strings (in
                     15:  * ascending order by source values).  The actual code strings are
                     16:  * reconstructed from the lengths in the inflate process, as described
                     17:  * in the deflate specification.
                     18:  *
                     19:  *  REFERENCES
                     20:  *
                     21:  *      Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
                     22:  *      Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
                     23:  *
                     24:  *      Storer, James A.
                     25:  *          Data Compression:  Methods and Theory, pp. 49-50.
                     26:  *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
                     27:  *
                     28:  *      Sedgewick, R.
                     29:  *          Algorithms, p290.
                     30:  *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
                     31:  */
                     32: 
                     33: /* @(#) $Id$ */
                     34: 
                     35: /* #define GEN_TREES_H */
                     36: 
                     37: #include "deflate.h"
                     38: 
                     39: #ifdef DEBUG
                     40: #  include <ctype.h>
                     41: #endif
                     42: 
                     43: /* ===========================================================================
                     44:  * Constants
                     45:  */
                     46: 
                     47: #define MAX_BL_BITS 7
                     48: /* Bit length codes must not exceed MAX_BL_BITS bits */
                     49: 
                     50: #define END_BLOCK 256
                     51: /* end of block literal code */
                     52: 
                     53: #define REP_3_6      16
                     54: /* repeat previous bit length 3-6 times (2 bits of repeat count) */
                     55: 
                     56: #define REPZ_3_10    17
                     57: /* repeat a zero length 3-10 times  (3 bits of repeat count) */
                     58: 
                     59: #define REPZ_11_138  18
                     60: /* repeat a zero length 11-138 times  (7 bits of repeat count) */
                     61: 
                     62: local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
                     63:    = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};
                     64: 
                     65: local const int extra_dbits[D_CODES] /* extra bits for each distance code */
                     66:    = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
                     67: 
                     68: local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
                     69:    = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
                     70: 
                     71: local const uch bl_order[BL_CODES]
                     72:    = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
                     73: /* The lengths of the bit length codes are sent in order of decreasing
                     74:  * probability, to avoid transmitting the lengths for unused bit length codes.
                     75:  */
                     76: 
                     77: /* ===========================================================================
                     78:  * Local data. These are initialized only once.
                     79:  */
                     80: 
                     81: #define DIST_CODE_LEN  512 /* see definition of array dist_code below */
                     82: 
                     83: #if defined(GEN_TREES_H) || !defined(STDC)
                     84: /* non ANSI compilers may not accept trees.h */
                     85: 
                     86: local ct_data static_ltree[L_CODES+2];
                     87: /* The static literal tree. Since the bit lengths are imposed, there is no
                     88:  * need for the L_CODES extra codes used during heap construction. However
                     89:  * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
                     90:  * below).
                     91:  */
                     92: 
                     93: local ct_data static_dtree[D_CODES];
                     94: /* The static distance tree. (Actually a trivial tree since all codes use
                     95:  * 5 bits.)
                     96:  */
                     97: 
                     98: uch _dist_code[DIST_CODE_LEN];
                     99: /* Distance codes. The first 256 values correspond to the distances
                    100:  * 3 .. 258, the last 256 values correspond to the top 8 bits of
                    101:  * the 15 bit distances.
                    102:  */
                    103: 
                    104: uch _length_code[MAX_MATCH-MIN_MATCH+1];
                    105: /* length code for each normalized match length (0 == MIN_MATCH) */
                    106: 
                    107: local int base_length[LENGTH_CODES];
                    108: /* First normalized length for each code (0 = MIN_MATCH) */
                    109: 
                    110: local int base_dist[D_CODES];
                    111: /* First normalized distance for each code (0 = distance of 1) */
                    112: 
                    113: #else
                    114: #  include "trees.h"
                    115: #endif /* GEN_TREES_H */
                    116: 
                    117: struct static_tree_desc_s {
                    118:     const ct_data *static_tree;  /* static tree or NULL */
                    119:     const intf *extra_bits;      /* extra bits for each code or NULL */
                    120:     int     extra_base;          /* base index for extra_bits */
                    121:     int     elems;               /* max number of elements in the tree */
                    122:     int     max_length;          /* max bit length for the codes */
                    123: };
                    124: 
                    125: local static_tree_desc  static_l_desc =
                    126: {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
                    127: 
                    128: local static_tree_desc  static_d_desc =
                    129: {static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};
                    130: 
                    131: local static_tree_desc  static_bl_desc =
                    132: {(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};
                    133: 
                    134: /* ===========================================================================
                    135:  * Local (static) routines in this file.
                    136:  */
                    137: 
                    138: local void tr_static_init OF((void));
                    139: local void init_block     OF((deflate_state *s));
                    140: local void pqdownheap     OF((deflate_state *s, ct_data *tree, int k));
                    141: local void gen_bitlen     OF((deflate_state *s, tree_desc *desc));
                    142: local void gen_codes      OF((ct_data *tree, int max_code, ushf *bl_count));
                    143: local void build_tree     OF((deflate_state *s, tree_desc *desc));
                    144: local void scan_tree      OF((deflate_state *s, ct_data *tree, int max_code));
                    145: local void send_tree      OF((deflate_state *s, ct_data *tree, int max_code));
                    146: local int  build_bl_tree  OF((deflate_state *s));
                    147: local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
                    148:                               int blcodes));
                    149: local void compress_block OF((deflate_state *s, ct_data *ltree,
                    150:                               ct_data *dtree));
                    151: local int  detect_data_type OF((deflate_state *s));
                    152: local unsigned bi_reverse OF((unsigned value, int length));
                    153: local void bi_windup      OF((deflate_state *s));
                    154: local void bi_flush       OF((deflate_state *s));
                    155: local void copy_block     OF((deflate_state *s, charf *buf, unsigned len,
                    156:                               int header));
                    157: 
                    158: #ifdef GEN_TREES_H
                    159: local void gen_trees_header OF((void));
                    160: #endif
                    161: 
                    162: #ifndef DEBUG
                    163: #  define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
                    164:    /* Send a code of the given tree. c and tree must not have side effects */
                    165: 
                    166: #else /* DEBUG */
                    167: #  define send_code(s, c, tree) \
                    168:      { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
                    169:        send_bits(s, tree[c].Code, tree[c].Len); }
                    170: #endif
                    171: 
                    172: /* ===========================================================================
                    173:  * Output a short LSB first on the stream.
                    174:  * IN assertion: there is enough room in pendingBuf.
                    175:  */
                    176: #define put_short(s, w) { \
                    177:     put_byte(s, (uch)((w) & 0xff)); \
                    178:     put_byte(s, (uch)((ush)(w) >> 8)); \
                    179: }
                    180: 
                    181: /* ===========================================================================
                    182:  * Send a value on a given number of bits.
                    183:  * IN assertion: length <= 16 and value fits in length bits.
                    184:  */
                    185: #ifdef DEBUG
                    186: local void send_bits      OF((deflate_state *s, int value, int length));
                    187: 
                    188: local void send_bits(s, value, length)
                    189:     deflate_state *s;
                    190:     int value;  /* value to send */
                    191:     int length; /* number of bits */
                    192: {
                    193:     Tracevv((stderr," l %2d v %4x ", length, value));
                    194:     Assert(length > 0 && length <= 15, "invalid length");
                    195:     s->bits_sent += (ulg)length;
                    196: 
                    197:     /* If not enough room in bi_buf, use (valid) bits from bi_buf and
                    198:      * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
                    199:      * unused bits in value.
                    200:      */
                    201:     if (s->bi_valid > (int)Buf_size - length) {
                    202:         s->bi_buf |= (ush)value << s->bi_valid;
                    203:         put_short(s, s->bi_buf);
                    204:         s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
                    205:         s->bi_valid += length - Buf_size;
                    206:     } else {
                    207:         s->bi_buf |= (ush)value << s->bi_valid;
                    208:         s->bi_valid += length;
                    209:     }
                    210: }
                    211: #else /* !DEBUG */
                    212: 
                    213: #define send_bits(s, value, length) \
                    214: { int len = length;\
                    215:   if (s->bi_valid > (int)Buf_size - len) {\
                    216:     int val = value;\
                    217:     s->bi_buf |= (ush)val << s->bi_valid;\
                    218:     put_short(s, s->bi_buf);\
                    219:     s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
                    220:     s->bi_valid += len - Buf_size;\
                    221:   } else {\
                    222:     s->bi_buf |= (ush)(value) << s->bi_valid;\
                    223:     s->bi_valid += len;\
                    224:   }\
                    225: }
                    226: #endif /* DEBUG */
                    227: 
                    228: 
                    229: /* the arguments must not have side effects */
                    230: 
                    231: /* ===========================================================================
                    232:  * Initialize the various 'constant' tables.
                    233:  */
                    234: local void tr_static_init()
                    235: {
                    236: #if defined(GEN_TREES_H) || !defined(STDC)
                    237:     static int static_init_done = 0;
                    238:     int n;        /* iterates over tree elements */
                    239:     int bits;     /* bit counter */
                    240:     int length;   /* length value */
                    241:     int code;     /* code value */
                    242:     int dist;     /* distance index */
                    243:     ush bl_count[MAX_BITS+1];
                    244:     /* number of codes at each bit length for an optimal tree */
                    245: 
                    246:     if (static_init_done) return;
                    247: 
                    248:     /* For some embedded targets, global variables are not initialized: */
                    249: #ifdef NO_INIT_GLOBAL_POINTERS
                    250:     static_l_desc.static_tree = static_ltree;
                    251:     static_l_desc.extra_bits = extra_lbits;
                    252:     static_d_desc.static_tree = static_dtree;
                    253:     static_d_desc.extra_bits = extra_dbits;
                    254:     static_bl_desc.extra_bits = extra_blbits;
                    255: #endif
                    256: 
                    257:     /* Initialize the mapping length (0..255) -> length code (0..28) */
                    258:     length = 0;
                    259:     for (code = 0; code < LENGTH_CODES-1; code++) {
                    260:         base_length[code] = length;
                    261:         for (n = 0; n < (1<<extra_lbits[code]); n++) {
                    262:             _length_code[length++] = (uch)code;
                    263:         }
                    264:     }
                    265:     Assert (length == 256, "tr_static_init: length != 256");
                    266:     /* Note that the length 255 (match length 258) can be represented
                    267:      * in two different ways: code 284 + 5 bits or code 285, so we
                    268:      * overwrite length_code[255] to use the best encoding:
                    269:      */
                    270:     _length_code[length-1] = (uch)code;
                    271: 
                    272:     /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
                    273:     dist = 0;
                    274:     for (code = 0 ; code < 16; code++) {
                    275:         base_dist[code] = dist;
                    276:         for (n = 0; n < (1<<extra_dbits[code]); n++) {
                    277:             _dist_code[dist++] = (uch)code;
                    278:         }
                    279:     }
                    280:     Assert (dist == 256, "tr_static_init: dist != 256");
                    281:     dist >>= 7; /* from now on, all distances are divided by 128 */
                    282:     for ( ; code < D_CODES; code++) {
                    283:         base_dist[code] = dist << 7;
                    284:         for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
                    285:             _dist_code[256 + dist++] = (uch)code;
                    286:         }
                    287:     }
                    288:     Assert (dist == 256, "tr_static_init: 256+dist != 512");
                    289: 
                    290:     /* Construct the codes of the static literal tree */
                    291:     for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
                    292:     n = 0;
                    293:     while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
                    294:     while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
                    295:     while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
                    296:     while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
                    297:     /* Codes 286 and 287 do not exist, but we must include them in the
                    298:      * tree construction to get a canonical Huffman tree (longest code
                    299:      * all ones)
                    300:      */
                    301:     gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
                    302: 
                    303:     /* The static distance tree is trivial: */
                    304:     for (n = 0; n < D_CODES; n++) {
                    305:         static_dtree[n].Len = 5;
                    306:         static_dtree[n].Code = bi_reverse((unsigned)n, 5);
                    307:     }
                    308:     static_init_done = 1;
                    309: 
                    310: #  ifdef GEN_TREES_H
                    311:     gen_trees_header();
                    312: #  endif
                    313: #endif /* defined(GEN_TREES_H) || !defined(STDC) */
                    314: }
                    315: 
                    316: /* ===========================================================================
                    317:  * Genererate the file trees.h describing the static trees.
                    318:  */
                    319: #ifdef GEN_TREES_H
                    320: #  ifndef DEBUG
                    321: #    include <stdio.h>
                    322: #  endif
                    323: 
                    324: #  define SEPARATOR(i, last, width) \
                    325:       ((i) == (last)? "\n};\n\n" :    \
                    326:        ((i) % (width) == (width)-1 ? ",\n" : ", "))
                    327: 
                    328: void gen_trees_header()
                    329: {
                    330:     FILE *header = fopen("trees.h", "w");
                    331:     int i;
                    332: 
                    333:     Assert (header != NULL, "Can't open trees.h");
                    334:     fprintf(header,
                    335:             "/* header created automatically with -DGEN_TREES_H */\n\n");
                    336: 
                    337:     fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
                    338:     for (i = 0; i < L_CODES+2; i++) {
                    339:         fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
                    340:                 static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
                    341:     }
                    342: 
                    343:     fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
                    344:     for (i = 0; i < D_CODES; i++) {
                    345:         fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
                    346:                 static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
                    347:     }
                    348: 
                    349:     fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
                    350:     for (i = 0; i < DIST_CODE_LEN; i++) {
                    351:         fprintf(header, "%2u%s", _dist_code[i],
                    352:                 SEPARATOR(i, DIST_CODE_LEN-1, 20));
                    353:     }
                    354: 
                    355:     fprintf(header,
                    356:         "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
                    357:     for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
                    358:         fprintf(header, "%2u%s", _length_code[i],
                    359:                 SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
                    360:     }
                    361: 
                    362:     fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
                    363:     for (i = 0; i < LENGTH_CODES; i++) {
                    364:         fprintf(header, "%1u%s", base_length[i],
                    365:                 SEPARATOR(i, LENGTH_CODES-1, 20));
                    366:     }
                    367: 
                    368:     fprintf(header, "local const int base_dist[D_CODES] = {\n");
                    369:     for (i = 0; i < D_CODES; i++) {
                    370:         fprintf(header, "%5u%s", base_dist[i],
                    371:                 SEPARATOR(i, D_CODES-1, 10));
                    372:     }
                    373: 
                    374:     fclose(header);
                    375: }
                    376: #endif /* GEN_TREES_H */
                    377: 
                    378: /* ===========================================================================
                    379:  * Initialize the tree data structures for a new zlib stream.
                    380:  */
                    381: void ZLIB_INTERNAL _tr_init(s)
                    382:     deflate_state *s;
                    383: {
                    384:     tr_static_init();
                    385: 
                    386:     s->l_desc.dyn_tree = s->dyn_ltree;
                    387:     s->l_desc.stat_desc = &static_l_desc;
                    388: 
                    389:     s->d_desc.dyn_tree = s->dyn_dtree;
                    390:     s->d_desc.stat_desc = &static_d_desc;
                    391: 
                    392:     s->bl_desc.dyn_tree = s->bl_tree;
                    393:     s->bl_desc.stat_desc = &static_bl_desc;
                    394: 
                    395:     s->bi_buf = 0;
                    396:     s->bi_valid = 0;
                    397: #ifdef DEBUG
                    398:     s->compressed_len = 0L;
                    399:     s->bits_sent = 0L;
                    400: #endif
                    401: 
                    402:     /* Initialize the first block of the first file: */
                    403:     init_block(s);
                    404: }
                    405: 
                    406: /* ===========================================================================
                    407:  * Initialize a new block.
                    408:  */
                    409: local void init_block(s)
                    410:     deflate_state *s;
                    411: {
                    412:     int n; /* iterates over tree elements */
                    413: 
                    414:     /* Initialize the trees. */
                    415:     for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
                    416:     for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
                    417:     for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
                    418: 
                    419:     s->dyn_ltree[END_BLOCK].Freq = 1;
                    420:     s->opt_len = s->static_len = 0L;
                    421:     s->last_lit = s->matches = 0;
                    422: }
                    423: 
                    424: #define SMALLEST 1
                    425: /* Index within the heap array of least frequent node in the Huffman tree */
                    426: 
                    427: 
                    428: /* ===========================================================================
                    429:  * Remove the smallest element from the heap and recreate the heap with
                    430:  * one less element. Updates heap and heap_len.
                    431:  */
                    432: #define pqremove(s, tree, top) \
                    433: {\
                    434:     top = s->heap[SMALLEST]; \
                    435:     s->heap[SMALLEST] = s->heap[s->heap_len--]; \
                    436:     pqdownheap(s, tree, SMALLEST); \
                    437: }
                    438: 
                    439: /* ===========================================================================
                    440:  * Compares to subtrees, using the tree depth as tie breaker when
                    441:  * the subtrees have equal frequency. This minimizes the worst case length.
                    442:  */
                    443: #define smaller(tree, n, m, depth) \
                    444:    (tree[n].Freq < tree[m].Freq || \
                    445:    (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
                    446: 
                    447: /* ===========================================================================
                    448:  * Restore the heap property by moving down the tree starting at node k,
                    449:  * exchanging a node with the smallest of its two sons if necessary, stopping
                    450:  * when the heap property is re-established (each father smaller than its
                    451:  * two sons).
                    452:  */
                    453: local void pqdownheap(s, tree, k)
                    454:     deflate_state *s;
                    455:     ct_data *tree;  /* the tree to restore */
                    456:     int k;               /* node to move down */
                    457: {
                    458:     int v = s->heap[k];
                    459:     int j = k << 1;  /* left son of k */
                    460:     while (j <= s->heap_len) {
                    461:         /* Set j to the smallest of the two sons: */
                    462:         if (j < s->heap_len &&
                    463:             smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
                    464:             j++;
                    465:         }
                    466:         /* Exit if v is smaller than both sons */
                    467:         if (smaller(tree, v, s->heap[j], s->depth)) break;
                    468: 
                    469:         /* Exchange v with the smallest son */
                    470:         s->heap[k] = s->heap[j];  k = j;
                    471: 
                    472:         /* And continue down the tree, setting j to the left son of k */
                    473:         j <<= 1;
                    474:     }
                    475:     s->heap[k] = v;
                    476: }
                    477: 
                    478: /* ===========================================================================
                    479:  * Compute the optimal bit lengths for a tree and update the total bit length
                    480:  * for the current block.
                    481:  * IN assertion: the fields freq and dad are set, heap[heap_max] and
                    482:  *    above are the tree nodes sorted by increasing frequency.
                    483:  * OUT assertions: the field len is set to the optimal bit length, the
                    484:  *     array bl_count contains the frequencies for each bit length.
                    485:  *     The length opt_len is updated; static_len is also updated if stree is
                    486:  *     not null.
                    487:  */
                    488: local void gen_bitlen(s, desc)
                    489:     deflate_state *s;
                    490:     tree_desc *desc;    /* the tree descriptor */
                    491: {
                    492:     ct_data *tree        = desc->dyn_tree;
                    493:     int max_code         = desc->max_code;
                    494:     const ct_data *stree = desc->stat_desc->static_tree;
                    495:     const intf *extra    = desc->stat_desc->extra_bits;
                    496:     int base             = desc->stat_desc->extra_base;
                    497:     int max_length       = desc->stat_desc->max_length;
                    498:     int h;              /* heap index */
                    499:     int n, m;           /* iterate over the tree elements */
                    500:     int bits;           /* bit length */
                    501:     int xbits;          /* extra bits */
                    502:     ush f;              /* frequency */
                    503:     int overflow = 0;   /* number of elements with bit length too large */
                    504: 
                    505:     for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
                    506: 
                    507:     /* In a first pass, compute the optimal bit lengths (which may
                    508:      * overflow in the case of the bit length tree).
                    509:      */
                    510:     tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
                    511: 
                    512:     for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
                    513:         n = s->heap[h];
                    514:         bits = tree[tree[n].Dad].Len + 1;
                    515:         if (bits > max_length) bits = max_length, overflow++;
                    516:         tree[n].Len = (ush)bits;
                    517:         /* We overwrite tree[n].Dad which is no longer needed */
                    518: 
                    519:         if (n > max_code) continue; /* not a leaf node */
                    520: 
                    521:         s->bl_count[bits]++;
                    522:         xbits = 0;
                    523:         if (n >= base) xbits = extra[n-base];
                    524:         f = tree[n].Freq;
                    525:         s->opt_len += (ulg)f * (bits + xbits);
                    526:         if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
                    527:     }
                    528:     if (overflow == 0) return;
                    529: 
                    530:     Trace((stderr,"\nbit length overflow\n"));
                    531:     /* This happens for example on obj2 and pic of the Calgary corpus */
                    532: 
                    533:     /* Find the first bit length which could increase: */
                    534:     do {
                    535:         bits = max_length-1;
                    536:         while (s->bl_count[bits] == 0) bits--;
                    537:         s->bl_count[bits]--;      /* move one leaf down the tree */
                    538:         s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
                    539:         s->bl_count[max_length]--;
                    540:         /* The brother of the overflow item also moves one step up,
                    541:          * but this does not affect bl_count[max_length]
                    542:          */
                    543:         overflow -= 2;
                    544:     } while (overflow > 0);
                    545: 
                    546:     /* Now recompute all bit lengths, scanning in increasing frequency.
                    547:      * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
                    548:      * lengths instead of fixing only the wrong ones. This idea is taken
                    549:      * from 'ar' written by Haruhiko Okumura.)
                    550:      */
                    551:     for (bits = max_length; bits != 0; bits--) {
                    552:         n = s->bl_count[bits];
                    553:         while (n != 0) {
                    554:             m = s->heap[--h];
                    555:             if (m > max_code) continue;
                    556:             if ((unsigned) tree[m].Len != (unsigned) bits) {
                    557:                 Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
                    558:                 s->opt_len += ((long)bits - (long)tree[m].Len)
                    559:                               *(long)tree[m].Freq;
                    560:                 tree[m].Len = (ush)bits;
                    561:             }
                    562:             n--;
                    563:         }
                    564:     }
                    565: }
                    566: 
                    567: /* ===========================================================================
                    568:  * Generate the codes for a given tree and bit counts (which need not be
                    569:  * optimal).
                    570:  * IN assertion: the array bl_count contains the bit length statistics for
                    571:  * the given tree and the field len is set for all tree elements.
                    572:  * OUT assertion: the field code is set for all tree elements of non
                    573:  *     zero code length.
                    574:  */
                    575: local void gen_codes (tree, max_code, bl_count)
                    576:     ct_data *tree;             /* the tree to decorate */
                    577:     int max_code;              /* largest code with non zero frequency */
                    578:     ushf *bl_count;            /* number of codes at each bit length */
                    579: {
                    580:     ush next_code[MAX_BITS+1]; /* next code value for each bit length */
                    581:     ush code = 0;              /* running code value */
                    582:     int bits;                  /* bit index */
                    583:     int n;                     /* code index */
                    584: 
                    585:     /* The distribution counts are first used to generate the code values
                    586:      * without bit reversal.
                    587:      */
                    588:     for (bits = 1; bits <= MAX_BITS; bits++) {
                    589:         next_code[bits] = code = (code + bl_count[bits-1]) << 1;
                    590:     }
                    591:     /* Check that the bit counts in bl_count are consistent. The last code
                    592:      * must be all ones.
                    593:      */
                    594:     Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
                    595:             "inconsistent bit counts");
                    596:     Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
                    597: 
                    598:     for (n = 0;  n <= max_code; n++) {
                    599:         int len = tree[n].Len;
                    600:         if (len == 0) continue;
                    601:         /* Now reverse the bits */
                    602:         tree[n].Code = bi_reverse(next_code[len]++, len);
                    603: 
                    604:         Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
                    605:              n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
                    606:     }
                    607: }
                    608: 
                    609: /* ===========================================================================
                    610:  * Construct one Huffman tree and assigns the code bit strings and lengths.
                    611:  * Update the total bit length for the current block.
                    612:  * IN assertion: the field freq is set for all tree elements.
                    613:  * OUT assertions: the fields len and code are set to the optimal bit length
                    614:  *     and corresponding code. The length opt_len is updated; static_len is
                    615:  *     also updated if stree is not null. The field max_code is set.
                    616:  */
                    617: local void build_tree(s, desc)
                    618:     deflate_state *s;
                    619:     tree_desc *desc; /* the tree descriptor */
                    620: {
                    621:     ct_data *tree         = desc->dyn_tree;
                    622:     const ct_data *stree  = desc->stat_desc->static_tree;
                    623:     int elems             = desc->stat_desc->elems;
                    624:     int n, m;          /* iterate over heap elements */
                    625:     int max_code = -1; /* largest code with non zero frequency */
                    626:     int node;          /* new node being created */
                    627: 
                    628:     /* Construct the initial heap, with least frequent element in
                    629:      * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
                    630:      * heap[0] is not used.
                    631:      */
                    632:     s->heap_len = 0, s->heap_max = HEAP_SIZE;
                    633: 
                    634:     for (n = 0; n < elems; n++) {
                    635:         if (tree[n].Freq != 0) {
                    636:             s->heap[++(s->heap_len)] = max_code = n;
                    637:             s->depth[n] = 0;
                    638:         } else {
                    639:             tree[n].Len = 0;
                    640:         }
                    641:     }
                    642: 
                    643:     /* The pkzip format requires that at least one distance code exists,
                    644:      * and that at least one bit should be sent even if there is only one
                    645:      * possible code. So to avoid special checks later on we force at least
                    646:      * two codes of non zero frequency.
                    647:      */
                    648:     while (s->heap_len < 2) {
                    649:         node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
                    650:         tree[node].Freq = 1;
                    651:         s->depth[node] = 0;
                    652:         s->opt_len--; if (stree) s->static_len -= stree[node].Len;
                    653:         /* node is 0 or 1 so it does not have extra bits */
                    654:     }
                    655:     desc->max_code = max_code;
                    656: 
                    657:     /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
                    658:      * establish sub-heaps of increasing lengths:
                    659:      */
                    660:     for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
                    661: 
                    662:     /* Construct the Huffman tree by repeatedly combining the least two
                    663:      * frequent nodes.
                    664:      */
                    665:     node = elems;              /* next internal node of the tree */
                    666:     do {
                    667:         pqremove(s, tree, n);  /* n = node of least frequency */
                    668:         m = s->heap[SMALLEST]; /* m = node of next least frequency */
                    669: 
                    670:         s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
                    671:         s->heap[--(s->heap_max)] = m;
                    672: 
                    673:         /* Create a new node father of n and m */
                    674:         tree[node].Freq = tree[n].Freq + tree[m].Freq;
                    675:         s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
                    676:                                 s->depth[n] : s->depth[m]) + 1);
                    677:         tree[n].Dad = tree[m].Dad = (ush)node;
                    678: #ifdef DUMP_BL_TREE
                    679:         if (tree == s->bl_tree) {
                    680:             fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
                    681:                     node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
                    682:         }
                    683: #endif
                    684:         /* and insert the new node in the heap */
                    685:         s->heap[SMALLEST] = node++;
                    686:         pqdownheap(s, tree, SMALLEST);
                    687: 
                    688:     } while (s->heap_len >= 2);
                    689: 
                    690:     s->heap[--(s->heap_max)] = s->heap[SMALLEST];
                    691: 
                    692:     /* At this point, the fields freq and dad are set. We can now
                    693:      * generate the bit lengths.
                    694:      */
                    695:     gen_bitlen(s, (tree_desc *)desc);
                    696: 
                    697:     /* The field len is now set, we can generate the bit codes */
                    698:     gen_codes ((ct_data *)tree, max_code, s->bl_count);
                    699: }
                    700: 
                    701: /* ===========================================================================
                    702:  * Scan a literal or distance tree to determine the frequencies of the codes
                    703:  * in the bit length tree.
                    704:  */
                    705: local void scan_tree (s, tree, max_code)
                    706:     deflate_state *s;
                    707:     ct_data *tree;   /* the tree to be scanned */
                    708:     int max_code;    /* and its largest code of non zero frequency */
                    709: {
                    710:     int n;                     /* iterates over all tree elements */
                    711:     int prevlen = -1;          /* last emitted length */
                    712:     int curlen;                /* length of current code */
                    713:     int nextlen = tree[0].Len; /* length of next code */
                    714:     int count = 0;             /* repeat count of the current code */
                    715:     int max_count = 7;         /* max repeat count */
                    716:     int min_count = 4;         /* min repeat count */
                    717: 
                    718:     if (nextlen == 0) max_count = 138, min_count = 3;
                    719:     tree[max_code+1].Len = (ush)0xffff; /* guard */
                    720: 
                    721:     for (n = 0; n <= max_code; n++) {
                    722:         curlen = nextlen; nextlen = tree[n+1].Len;
                    723:         if (++count < max_count && curlen == nextlen) {
                    724:             continue;
                    725:         } else if (count < min_count) {
                    726:             s->bl_tree[curlen].Freq += count;
                    727:         } else if (curlen != 0) {
                    728:             if (curlen != prevlen) s->bl_tree[curlen].Freq++;
                    729:             s->bl_tree[REP_3_6].Freq++;
                    730:         } else if (count <= 10) {
                    731:             s->bl_tree[REPZ_3_10].Freq++;
                    732:         } else {
                    733:             s->bl_tree[REPZ_11_138].Freq++;
                    734:         }
                    735:         count = 0; prevlen = curlen;
                    736:         if (nextlen == 0) {
                    737:             max_count = 138, min_count = 3;
                    738:         } else if (curlen == nextlen) {
                    739:             max_count = 6, min_count = 3;
                    740:         } else {
                    741:             max_count = 7, min_count = 4;
                    742:         }
                    743:     }
                    744: }
                    745: 
                    746: /* ===========================================================================
                    747:  * Send a literal or distance tree in compressed form, using the codes in
                    748:  * bl_tree.
                    749:  */
                    750: local void send_tree (s, tree, max_code)
                    751:     deflate_state *s;
                    752:     ct_data *tree; /* the tree to be scanned */
                    753:     int max_code;       /* and its largest code of non zero frequency */
                    754: {
                    755:     int n;                     /* iterates over all tree elements */
                    756:     int prevlen = -1;          /* last emitted length */
                    757:     int curlen;                /* length of current code */
                    758:     int nextlen = tree[0].Len; /* length of next code */
                    759:     int count = 0;             /* repeat count of the current code */
                    760:     int max_count = 7;         /* max repeat count */
                    761:     int min_count = 4;         /* min repeat count */
                    762: 
                    763:     /* tree[max_code+1].Len = -1; */  /* guard already set */
                    764:     if (nextlen == 0) max_count = 138, min_count = 3;
                    765: 
                    766:     for (n = 0; n <= max_code; n++) {
                    767:         curlen = nextlen; nextlen = tree[n+1].Len;
                    768:         if (++count < max_count && curlen == nextlen) {
                    769:             continue;
                    770:         } else if (count < min_count) {
                    771:             do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
                    772: 
                    773:         } else if (curlen != 0) {
                    774:             if (curlen != prevlen) {
                    775:                 send_code(s, curlen, s->bl_tree); count--;
                    776:             }
                    777:             Assert(count >= 3 && count <= 6, " 3_6?");
                    778:             send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
                    779: 
                    780:         } else if (count <= 10) {
                    781:             send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
                    782: 
                    783:         } else {
                    784:             send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
                    785:         }
                    786:         count = 0; prevlen = curlen;
                    787:         if (nextlen == 0) {
                    788:             max_count = 138, min_count = 3;
                    789:         } else if (curlen == nextlen) {
                    790:             max_count = 6, min_count = 3;
                    791:         } else {
                    792:             max_count = 7, min_count = 4;
                    793:         }
                    794:     }
                    795: }
                    796: 
                    797: /* ===========================================================================
                    798:  * Construct the Huffman tree for the bit lengths and return the index in
                    799:  * bl_order of the last bit length code to send.
                    800:  */
                    801: local int build_bl_tree(s)
                    802:     deflate_state *s;
                    803: {
                    804:     int max_blindex;  /* index of last bit length code of non zero freq */
                    805: 
                    806:     /* Determine the bit length frequencies for literal and distance trees */
                    807:     scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
                    808:     scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
                    809: 
                    810:     /* Build the bit length tree: */
                    811:     build_tree(s, (tree_desc *)(&(s->bl_desc)));
                    812:     /* opt_len now includes the length of the tree representations, except
                    813:      * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
                    814:      */
                    815: 
                    816:     /* Determine the number of bit length codes to send. The pkzip format
                    817:      * requires that at least 4 bit length codes be sent. (appnote.txt says
                    818:      * 3 but the actual value used is 4.)
                    819:      */
                    820:     for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
                    821:         if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
                    822:     }
                    823:     /* Update opt_len to include the bit length tree and counts */
                    824:     s->opt_len += 3*(max_blindex+1) + 5+5+4;
                    825:     Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
                    826:             s->opt_len, s->static_len));
                    827: 
                    828:     return max_blindex;
                    829: }
                    830: 
                    831: /* ===========================================================================
                    832:  * Send the header for a block using dynamic Huffman trees: the counts, the
                    833:  * lengths of the bit length codes, the literal tree and the distance tree.
                    834:  * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
                    835:  */
                    836: local void send_all_trees(s, lcodes, dcodes, blcodes)
                    837:     deflate_state *s;
                    838:     int lcodes, dcodes, blcodes; /* number of codes for each tree */
                    839: {
                    840:     int rank;                    /* index in bl_order */
                    841: 
                    842:     Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
                    843:     Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
                    844:             "too many codes");
                    845:     Tracev((stderr, "\nbl counts: "));
                    846:     send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
                    847:     send_bits(s, dcodes-1,   5);
                    848:     send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
                    849:     for (rank = 0; rank < blcodes; rank++) {
                    850:         Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
                    851:         send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
                    852:     }
                    853:     Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
                    854: 
                    855:     send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
                    856:     Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
                    857: 
                    858:     send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
                    859:     Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
                    860: }
                    861: 
                    862: /* ===========================================================================
                    863:  * Send a stored block
                    864:  */
                    865: void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
                    866:     deflate_state *s;
                    867:     charf *buf;       /* input block */
                    868:     ulg stored_len;   /* length of input block */
                    869:     int last;         /* one if this is the last block for a file */
                    870: {
                    871:     send_bits(s, (STORED_BLOCK<<1)+last, 3);    /* send block type */
                    872: #ifdef DEBUG
                    873:     s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
                    874:     s->compressed_len += (stored_len + 4) << 3;
                    875: #endif
                    876:     copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
                    877: }
                    878: 
                    879: /* ===========================================================================
1.1.1.2 ! misho     880:  * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
        !           881:  */
        !           882: void ZLIB_INTERNAL _tr_flush_bits(s)
        !           883:     deflate_state *s;
        !           884: {
        !           885:     bi_flush(s);
        !           886: }
        !           887: 
        !           888: /* ===========================================================================
1.1       misho     889:  * Send one empty static block to give enough lookahead for inflate.
                    890:  * This takes 10 bits, of which 7 may remain in the bit buffer.
                    891:  */
                    892: void ZLIB_INTERNAL _tr_align(s)
                    893:     deflate_state *s;
                    894: {
                    895:     send_bits(s, STATIC_TREES<<1, 3);
                    896:     send_code(s, END_BLOCK, static_ltree);
                    897: #ifdef DEBUG
                    898:     s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
                    899: #endif
                    900:     bi_flush(s);
                    901: }
                    902: 
                    903: /* ===========================================================================
                    904:  * Determine the best encoding for the current block: dynamic trees, static
                    905:  * trees or store, and output the encoded block to the zip file.
                    906:  */
                    907: void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
                    908:     deflate_state *s;
                    909:     charf *buf;       /* input block, or NULL if too old */
                    910:     ulg stored_len;   /* length of input block */
                    911:     int last;         /* one if this is the last block for a file */
                    912: {
                    913:     ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
                    914:     int max_blindex = 0;  /* index of last bit length code of non zero freq */
                    915: 
                    916:     /* Build the Huffman trees unless a stored block is forced */
                    917:     if (s->level > 0) {
                    918: 
                    919:         /* Check if the file is binary or text */
                    920:         if (s->strm->data_type == Z_UNKNOWN)
                    921:             s->strm->data_type = detect_data_type(s);
                    922: 
                    923:         /* Construct the literal and distance trees */
                    924:         build_tree(s, (tree_desc *)(&(s->l_desc)));
                    925:         Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
                    926:                 s->static_len));
                    927: 
                    928:         build_tree(s, (tree_desc *)(&(s->d_desc)));
                    929:         Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
                    930:                 s->static_len));
                    931:         /* At this point, opt_len and static_len are the total bit lengths of
                    932:          * the compressed block data, excluding the tree representations.
                    933:          */
                    934: 
                    935:         /* Build the bit length tree for the above two trees, and get the index
                    936:          * in bl_order of the last bit length code to send.
                    937:          */
                    938:         max_blindex = build_bl_tree(s);
                    939: 
                    940:         /* Determine the best encoding. Compute the block lengths in bytes. */
                    941:         opt_lenb = (s->opt_len+3+7)>>3;
                    942:         static_lenb = (s->static_len+3+7)>>3;
                    943: 
                    944:         Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
                    945:                 opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
                    946:                 s->last_lit));
                    947: 
                    948:         if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
                    949: 
                    950:     } else {
                    951:         Assert(buf != (char*)0, "lost buf");
                    952:         opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
                    953:     }
                    954: 
                    955: #ifdef FORCE_STORED
                    956:     if (buf != (char*)0) { /* force stored block */
                    957: #else
                    958:     if (stored_len+4 <= opt_lenb && buf != (char*)0) {
                    959:                        /* 4: two words for the lengths */
                    960: #endif
                    961:         /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
                    962:          * Otherwise we can't have processed more than WSIZE input bytes since
                    963:          * the last block flush, because compression would have been
                    964:          * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
                    965:          * transform a block into a stored block.
                    966:          */
                    967:         _tr_stored_block(s, buf, stored_len, last);
                    968: 
                    969: #ifdef FORCE_STATIC
                    970:     } else if (static_lenb >= 0) { /* force static trees */
                    971: #else
                    972:     } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
                    973: #endif
                    974:         send_bits(s, (STATIC_TREES<<1)+last, 3);
                    975:         compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
                    976: #ifdef DEBUG
                    977:         s->compressed_len += 3 + s->static_len;
                    978: #endif
                    979:     } else {
                    980:         send_bits(s, (DYN_TREES<<1)+last, 3);
                    981:         send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
                    982:                        max_blindex+1);
                    983:         compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
                    984: #ifdef DEBUG
                    985:         s->compressed_len += 3 + s->opt_len;
                    986: #endif
                    987:     }
                    988:     Assert (s->compressed_len == s->bits_sent, "bad compressed size");
                    989:     /* The above check is made mod 2^32, for files larger than 512 MB
                    990:      * and uLong implemented on 32 bits.
                    991:      */
                    992:     init_block(s);
                    993: 
                    994:     if (last) {
                    995:         bi_windup(s);
                    996: #ifdef DEBUG
                    997:         s->compressed_len += 7;  /* align on byte boundary */
                    998: #endif
                    999:     }
                   1000:     Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
                   1001:            s->compressed_len-7*last));
                   1002: }
                   1003: 
                   1004: /* ===========================================================================
                   1005:  * Save the match info and tally the frequency counts. Return true if
                   1006:  * the current block must be flushed.
                   1007:  */
                   1008: int ZLIB_INTERNAL _tr_tally (s, dist, lc)
                   1009:     deflate_state *s;
                   1010:     unsigned dist;  /* distance of matched string */
                   1011:     unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
                   1012: {
                   1013:     s->d_buf[s->last_lit] = (ush)dist;
                   1014:     s->l_buf[s->last_lit++] = (uch)lc;
                   1015:     if (dist == 0) {
                   1016:         /* lc is the unmatched char */
                   1017:         s->dyn_ltree[lc].Freq++;
                   1018:     } else {
                   1019:         s->matches++;
                   1020:         /* Here, lc is the match length - MIN_MATCH */
                   1021:         dist--;             /* dist = match distance - 1 */
                   1022:         Assert((ush)dist < (ush)MAX_DIST(s) &&
                   1023:                (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
                   1024:                (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");
                   1025: 
                   1026:         s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
                   1027:         s->dyn_dtree[d_code(dist)].Freq++;
                   1028:     }
                   1029: 
                   1030: #ifdef TRUNCATE_BLOCK
                   1031:     /* Try to guess if it is profitable to stop the current block here */
                   1032:     if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
                   1033:         /* Compute an upper bound for the compressed length */
                   1034:         ulg out_length = (ulg)s->last_lit*8L;
                   1035:         ulg in_length = (ulg)((long)s->strstart - s->block_start);
                   1036:         int dcode;
                   1037:         for (dcode = 0; dcode < D_CODES; dcode++) {
                   1038:             out_length += (ulg)s->dyn_dtree[dcode].Freq *
                   1039:                 (5L+extra_dbits[dcode]);
                   1040:         }
                   1041:         out_length >>= 3;
                   1042:         Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
                   1043:                s->last_lit, in_length, out_length,
                   1044:                100L - out_length*100L/in_length));
                   1045:         if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
                   1046:     }
                   1047: #endif
                   1048:     return (s->last_lit == s->lit_bufsize-1);
                   1049:     /* We avoid equality with lit_bufsize because of wraparound at 64K
                   1050:      * on 16 bit machines and because stored blocks are restricted to
                   1051:      * 64K-1 bytes.
                   1052:      */
                   1053: }
                   1054: 
                   1055: /* ===========================================================================
                   1056:  * Send the block data compressed using the given Huffman trees
                   1057:  */
                   1058: local void compress_block(s, ltree, dtree)
                   1059:     deflate_state *s;
                   1060:     ct_data *ltree; /* literal tree */
                   1061:     ct_data *dtree; /* distance tree */
                   1062: {
                   1063:     unsigned dist;      /* distance of matched string */
                   1064:     int lc;             /* match length or unmatched char (if dist == 0) */
                   1065:     unsigned lx = 0;    /* running index in l_buf */
                   1066:     unsigned code;      /* the code to send */
                   1067:     int extra;          /* number of extra bits to send */
                   1068: 
                   1069:     if (s->last_lit != 0) do {
                   1070:         dist = s->d_buf[lx];
                   1071:         lc = s->l_buf[lx++];
                   1072:         if (dist == 0) {
                   1073:             send_code(s, lc, ltree); /* send a literal byte */
                   1074:             Tracecv(isgraph(lc), (stderr," '%c' ", lc));
                   1075:         } else {
                   1076:             /* Here, lc is the match length - MIN_MATCH */
                   1077:             code = _length_code[lc];
                   1078:             send_code(s, code+LITERALS+1, ltree); /* send the length code */
                   1079:             extra = extra_lbits[code];
                   1080:             if (extra != 0) {
                   1081:                 lc -= base_length[code];
                   1082:                 send_bits(s, lc, extra);       /* send the extra length bits */
                   1083:             }
                   1084:             dist--; /* dist is now the match distance - 1 */
                   1085:             code = d_code(dist);
                   1086:             Assert (code < D_CODES, "bad d_code");
                   1087: 
                   1088:             send_code(s, code, dtree);       /* send the distance code */
                   1089:             extra = extra_dbits[code];
                   1090:             if (extra != 0) {
                   1091:                 dist -= base_dist[code];
                   1092:                 send_bits(s, dist, extra);   /* send the extra distance bits */
                   1093:             }
                   1094:         } /* literal or match pair ? */
                   1095: 
                   1096:         /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
                   1097:         Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
                   1098:                "pendingBuf overflow");
                   1099: 
                   1100:     } while (lx < s->last_lit);
                   1101: 
                   1102:     send_code(s, END_BLOCK, ltree);
                   1103: }
                   1104: 
                   1105: /* ===========================================================================
                   1106:  * Check if the data type is TEXT or BINARY, using the following algorithm:
                   1107:  * - TEXT if the two conditions below are satisfied:
                   1108:  *    a) There are no non-portable control characters belonging to the
                   1109:  *       "black list" (0..6, 14..25, 28..31).
                   1110:  *    b) There is at least one printable character belonging to the
                   1111:  *       "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
                   1112:  * - BINARY otherwise.
                   1113:  * - The following partially-portable control characters form a
                   1114:  *   "gray list" that is ignored in this detection algorithm:
                   1115:  *   (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
                   1116:  * IN assertion: the fields Freq of dyn_ltree are set.
                   1117:  */
                   1118: local int detect_data_type(s)
                   1119:     deflate_state *s;
                   1120: {
                   1121:     /* black_mask is the bit mask of black-listed bytes
                   1122:      * set bits 0..6, 14..25, and 28..31
                   1123:      * 0xf3ffc07f = binary 11110011111111111100000001111111
                   1124:      */
                   1125:     unsigned long black_mask = 0xf3ffc07fUL;
                   1126:     int n;
                   1127: 
                   1128:     /* Check for non-textual ("black-listed") bytes. */
                   1129:     for (n = 0; n <= 31; n++, black_mask >>= 1)
                   1130:         if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
                   1131:             return Z_BINARY;
                   1132: 
                   1133:     /* Check for textual ("white-listed") bytes. */
                   1134:     if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
                   1135:             || s->dyn_ltree[13].Freq != 0)
                   1136:         return Z_TEXT;
                   1137:     for (n = 32; n < LITERALS; n++)
                   1138:         if (s->dyn_ltree[n].Freq != 0)
                   1139:             return Z_TEXT;
                   1140: 
                   1141:     /* There are no "black-listed" or "white-listed" bytes:
                   1142:      * this stream either is empty or has tolerated ("gray-listed") bytes only.
                   1143:      */
                   1144:     return Z_BINARY;
                   1145: }
                   1146: 
                   1147: /* ===========================================================================
                   1148:  * Reverse the first len bits of a code, using straightforward code (a faster
                   1149:  * method would use a table)
                   1150:  * IN assertion: 1 <= len <= 15
                   1151:  */
                   1152: local unsigned bi_reverse(code, len)
                   1153:     unsigned code; /* the value to invert */
                   1154:     int len;       /* its bit length */
                   1155: {
                   1156:     register unsigned res = 0;
                   1157:     do {
                   1158:         res |= code & 1;
                   1159:         code >>= 1, res <<= 1;
                   1160:     } while (--len > 0);
                   1161:     return res >> 1;
                   1162: }
                   1163: 
                   1164: /* ===========================================================================
                   1165:  * Flush the bit buffer, keeping at most 7 bits in it.
                   1166:  */
                   1167: local void bi_flush(s)
                   1168:     deflate_state *s;
                   1169: {
                   1170:     if (s->bi_valid == 16) {
                   1171:         put_short(s, s->bi_buf);
                   1172:         s->bi_buf = 0;
                   1173:         s->bi_valid = 0;
                   1174:     } else if (s->bi_valid >= 8) {
                   1175:         put_byte(s, (Byte)s->bi_buf);
                   1176:         s->bi_buf >>= 8;
                   1177:         s->bi_valid -= 8;
                   1178:     }
                   1179: }
                   1180: 
                   1181: /* ===========================================================================
                   1182:  * Flush the bit buffer and align the output on a byte boundary
                   1183:  */
                   1184: local void bi_windup(s)
                   1185:     deflate_state *s;
                   1186: {
                   1187:     if (s->bi_valid > 8) {
                   1188:         put_short(s, s->bi_buf);
                   1189:     } else if (s->bi_valid > 0) {
                   1190:         put_byte(s, (Byte)s->bi_buf);
                   1191:     }
                   1192:     s->bi_buf = 0;
                   1193:     s->bi_valid = 0;
                   1194: #ifdef DEBUG
                   1195:     s->bits_sent = (s->bits_sent+7) & ~7;
                   1196: #endif
                   1197: }
                   1198: 
                   1199: /* ===========================================================================
                   1200:  * Copy a stored block, storing first the length and its
                   1201:  * one's complement if requested.
                   1202:  */
                   1203: local void copy_block(s, buf, len, header)
                   1204:     deflate_state *s;
                   1205:     charf    *buf;    /* the input data */
                   1206:     unsigned len;     /* its length */
                   1207:     int      header;  /* true if block header must be written */
                   1208: {
                   1209:     bi_windup(s);        /* align on byte boundary */
                   1210: 
                   1211:     if (header) {
                   1212:         put_short(s, (ush)len);
                   1213:         put_short(s, (ush)~len);
                   1214: #ifdef DEBUG
                   1215:         s->bits_sent += 2*16;
                   1216: #endif
                   1217:     }
                   1218: #ifdef DEBUG
                   1219:     s->bits_sent += (ulg)len<<3;
                   1220: #endif
                   1221:     while (len--) {
                   1222:         put_byte(s, *buf++);
                   1223:     }
                   1224: }

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