Annotation of embedaddon/sudo/zlib/trees.c, revision 1.1
1.1 ! misho 1: /* trees.c -- output deflated data using Huffman coding
! 2: * Copyright (C) 1995-2010 Jean-loup Gailly
! 3: * detect_data_type() function provided freely by Cosmin Truta, 2006
! 4: * For conditions of distribution and use, see copyright notice in zlib.h
! 5: */
! 6:
! 7: /*
! 8: * ALGORITHM
! 9: *
! 10: * The "deflation" process uses several Huffman trees. The more
! 11: * common source values are represented by shorter bit sequences.
! 12: *
! 13: * Each code tree is stored in a compressed form which is itself
! 14: * a Huffman encoding of the lengths of all the code strings (in
! 15: * ascending order by source values). The actual code strings are
! 16: * reconstructed from the lengths in the inflate process, as described
! 17: * in the deflate specification.
! 18: *
! 19: * REFERENCES
! 20: *
! 21: * Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
! 22: * Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
! 23: *
! 24: * Storer, James A.
! 25: * Data Compression: Methods and Theory, pp. 49-50.
! 26: * Computer Science Press, 1988. ISBN 0-7167-8156-5.
! 27: *
! 28: * Sedgewick, R.
! 29: * Algorithms, p290.
! 30: * Addison-Wesley, 1983. ISBN 0-201-06672-6.
! 31: */
! 32:
! 33: /* @(#) $Id$ */
! 34:
! 35: /* #define GEN_TREES_H */
! 36:
! 37: #include "deflate.h"
! 38:
! 39: #ifdef DEBUG
! 40: # include <ctype.h>
! 41: #endif
! 42:
! 43: /* ===========================================================================
! 44: * Constants
! 45: */
! 46:
! 47: #define MAX_BL_BITS 7
! 48: /* Bit length codes must not exceed MAX_BL_BITS bits */
! 49:
! 50: #define END_BLOCK 256
! 51: /* end of block literal code */
! 52:
! 53: #define REP_3_6 16
! 54: /* repeat previous bit length 3-6 times (2 bits of repeat count) */
! 55:
! 56: #define REPZ_3_10 17
! 57: /* repeat a zero length 3-10 times (3 bits of repeat count) */
! 58:
! 59: #define REPZ_11_138 18
! 60: /* repeat a zero length 11-138 times (7 bits of repeat count) */
! 61:
! 62: local const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
! 63: = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};
! 64:
! 65: local const int extra_dbits[D_CODES] /* extra bits for each distance code */
! 66: = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
! 67:
! 68: local const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
! 69: = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
! 70:
! 71: local const uch bl_order[BL_CODES]
! 72: = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
! 73: /* The lengths of the bit length codes are sent in order of decreasing
! 74: * probability, to avoid transmitting the lengths for unused bit length codes.
! 75: */
! 76:
! 77: #define Buf_size (8 * 2*sizeof(char))
! 78: /* Number of bits used within bi_buf. (bi_buf might be implemented on
! 79: * more than 16 bits on some systems.)
! 80: */
! 81:
! 82: /* ===========================================================================
! 83: * Local data. These are initialized only once.
! 84: */
! 85:
! 86: #define DIST_CODE_LEN 512 /* see definition of array dist_code below */
! 87:
! 88: #if defined(GEN_TREES_H) || !defined(STDC)
! 89: /* non ANSI compilers may not accept trees.h */
! 90:
! 91: local ct_data static_ltree[L_CODES+2];
! 92: /* The static literal tree. Since the bit lengths are imposed, there is no
! 93: * need for the L_CODES extra codes used during heap construction. However
! 94: * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
! 95: * below).
! 96: */
! 97:
! 98: local ct_data static_dtree[D_CODES];
! 99: /* The static distance tree. (Actually a trivial tree since all codes use
! 100: * 5 bits.)
! 101: */
! 102:
! 103: uch _dist_code[DIST_CODE_LEN];
! 104: /* Distance codes. The first 256 values correspond to the distances
! 105: * 3 .. 258, the last 256 values correspond to the top 8 bits of
! 106: * the 15 bit distances.
! 107: */
! 108:
! 109: uch _length_code[MAX_MATCH-MIN_MATCH+1];
! 110: /* length code for each normalized match length (0 == MIN_MATCH) */
! 111:
! 112: local int base_length[LENGTH_CODES];
! 113: /* First normalized length for each code (0 = MIN_MATCH) */
! 114:
! 115: local int base_dist[D_CODES];
! 116: /* First normalized distance for each code (0 = distance of 1) */
! 117:
! 118: #else
! 119: # include "trees.h"
! 120: #endif /* GEN_TREES_H */
! 121:
! 122: struct static_tree_desc_s {
! 123: const ct_data *static_tree; /* static tree or NULL */
! 124: const intf *extra_bits; /* extra bits for each code or NULL */
! 125: int extra_base; /* base index for extra_bits */
! 126: int elems; /* max number of elements in the tree */
! 127: int max_length; /* max bit length for the codes */
! 128: };
! 129:
! 130: local static_tree_desc static_l_desc =
! 131: {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};
! 132:
! 133: local static_tree_desc static_d_desc =
! 134: {static_dtree, extra_dbits, 0, D_CODES, MAX_BITS};
! 135:
! 136: local static_tree_desc static_bl_desc =
! 137: {(const ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS};
! 138:
! 139: /* ===========================================================================
! 140: * Local (static) routines in this file.
! 141: */
! 142:
! 143: local void tr_static_init OF((void));
! 144: local void init_block OF((deflate_state *s));
! 145: local void pqdownheap OF((deflate_state *s, ct_data *tree, int k));
! 146: local void gen_bitlen OF((deflate_state *s, tree_desc *desc));
! 147: local void gen_codes OF((ct_data *tree, int max_code, ushf *bl_count));
! 148: local void build_tree OF((deflate_state *s, tree_desc *desc));
! 149: local void scan_tree OF((deflate_state *s, ct_data *tree, int max_code));
! 150: local void send_tree OF((deflate_state *s, ct_data *tree, int max_code));
! 151: local int build_bl_tree OF((deflate_state *s));
! 152: local void send_all_trees OF((deflate_state *s, int lcodes, int dcodes,
! 153: int blcodes));
! 154: local void compress_block OF((deflate_state *s, ct_data *ltree,
! 155: ct_data *dtree));
! 156: local int detect_data_type OF((deflate_state *s));
! 157: local unsigned bi_reverse OF((unsigned value, int length));
! 158: local void bi_windup OF((deflate_state *s));
! 159: local void bi_flush OF((deflate_state *s));
! 160: local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
! 161: int header));
! 162:
! 163: #ifdef GEN_TREES_H
! 164: local void gen_trees_header OF((void));
! 165: #endif
! 166:
! 167: #ifndef DEBUG
! 168: # define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
! 169: /* Send a code of the given tree. c and tree must not have side effects */
! 170:
! 171: #else /* DEBUG */
! 172: # define send_code(s, c, tree) \
! 173: { if (z_verbose>2) fprintf(stderr,"\ncd %3d ",(c)); \
! 174: send_bits(s, tree[c].Code, tree[c].Len); }
! 175: #endif
! 176:
! 177: /* ===========================================================================
! 178: * Output a short LSB first on the stream.
! 179: * IN assertion: there is enough room in pendingBuf.
! 180: */
! 181: #define put_short(s, w) { \
! 182: put_byte(s, (uch)((w) & 0xff)); \
! 183: put_byte(s, (uch)((ush)(w) >> 8)); \
! 184: }
! 185:
! 186: /* ===========================================================================
! 187: * Send a value on a given number of bits.
! 188: * IN assertion: length <= 16 and value fits in length bits.
! 189: */
! 190: #ifdef DEBUG
! 191: local void send_bits OF((deflate_state *s, int value, int length));
! 192:
! 193: local void send_bits(s, value, length)
! 194: deflate_state *s;
! 195: int value; /* value to send */
! 196: int length; /* number of bits */
! 197: {
! 198: Tracevv((stderr," l %2d v %4x ", length, value));
! 199: Assert(length > 0 && length <= 15, "invalid length");
! 200: s->bits_sent += (ulg)length;
! 201:
! 202: /* If not enough room in bi_buf, use (valid) bits from bi_buf and
! 203: * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
! 204: * unused bits in value.
! 205: */
! 206: if (s->bi_valid > (int)Buf_size - length) {
! 207: s->bi_buf |= (ush)value << s->bi_valid;
! 208: put_short(s, s->bi_buf);
! 209: s->bi_buf = (ush)value >> (Buf_size - s->bi_valid);
! 210: s->bi_valid += length - Buf_size;
! 211: } else {
! 212: s->bi_buf |= (ush)value << s->bi_valid;
! 213: s->bi_valid += length;
! 214: }
! 215: }
! 216: #else /* !DEBUG */
! 217:
! 218: #define send_bits(s, value, length) \
! 219: { int len = length;\
! 220: if (s->bi_valid > (int)Buf_size - len) {\
! 221: int val = value;\
! 222: s->bi_buf |= (ush)val << s->bi_valid;\
! 223: put_short(s, s->bi_buf);\
! 224: s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
! 225: s->bi_valid += len - Buf_size;\
! 226: } else {\
! 227: s->bi_buf |= (ush)(value) << s->bi_valid;\
! 228: s->bi_valid += len;\
! 229: }\
! 230: }
! 231: #endif /* DEBUG */
! 232:
! 233:
! 234: /* the arguments must not have side effects */
! 235:
! 236: /* ===========================================================================
! 237: * Initialize the various 'constant' tables.
! 238: */
! 239: local void tr_static_init()
! 240: {
! 241: #if defined(GEN_TREES_H) || !defined(STDC)
! 242: static int static_init_done = 0;
! 243: int n; /* iterates over tree elements */
! 244: int bits; /* bit counter */
! 245: int length; /* length value */
! 246: int code; /* code value */
! 247: int dist; /* distance index */
! 248: ush bl_count[MAX_BITS+1];
! 249: /* number of codes at each bit length for an optimal tree */
! 250:
! 251: if (static_init_done) return;
! 252:
! 253: /* For some embedded targets, global variables are not initialized: */
! 254: #ifdef NO_INIT_GLOBAL_POINTERS
! 255: static_l_desc.static_tree = static_ltree;
! 256: static_l_desc.extra_bits = extra_lbits;
! 257: static_d_desc.static_tree = static_dtree;
! 258: static_d_desc.extra_bits = extra_dbits;
! 259: static_bl_desc.extra_bits = extra_blbits;
! 260: #endif
! 261:
! 262: /* Initialize the mapping length (0..255) -> length code (0..28) */
! 263: length = 0;
! 264: for (code = 0; code < LENGTH_CODES-1; code++) {
! 265: base_length[code] = length;
! 266: for (n = 0; n < (1<<extra_lbits[code]); n++) {
! 267: _length_code[length++] = (uch)code;
! 268: }
! 269: }
! 270: Assert (length == 256, "tr_static_init: length != 256");
! 271: /* Note that the length 255 (match length 258) can be represented
! 272: * in two different ways: code 284 + 5 bits or code 285, so we
! 273: * overwrite length_code[255] to use the best encoding:
! 274: */
! 275: _length_code[length-1] = (uch)code;
! 276:
! 277: /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
! 278: dist = 0;
! 279: for (code = 0 ; code < 16; code++) {
! 280: base_dist[code] = dist;
! 281: for (n = 0; n < (1<<extra_dbits[code]); n++) {
! 282: _dist_code[dist++] = (uch)code;
! 283: }
! 284: }
! 285: Assert (dist == 256, "tr_static_init: dist != 256");
! 286: dist >>= 7; /* from now on, all distances are divided by 128 */
! 287: for ( ; code < D_CODES; code++) {
! 288: base_dist[code] = dist << 7;
! 289: for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
! 290: _dist_code[256 + dist++] = (uch)code;
! 291: }
! 292: }
! 293: Assert (dist == 256, "tr_static_init: 256+dist != 512");
! 294:
! 295: /* Construct the codes of the static literal tree */
! 296: for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
! 297: n = 0;
! 298: while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
! 299: while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
! 300: while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
! 301: while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
! 302: /* Codes 286 and 287 do not exist, but we must include them in the
! 303: * tree construction to get a canonical Huffman tree (longest code
! 304: * all ones)
! 305: */
! 306: gen_codes((ct_data *)static_ltree, L_CODES+1, bl_count);
! 307:
! 308: /* The static distance tree is trivial: */
! 309: for (n = 0; n < D_CODES; n++) {
! 310: static_dtree[n].Len = 5;
! 311: static_dtree[n].Code = bi_reverse((unsigned)n, 5);
! 312: }
! 313: static_init_done = 1;
! 314:
! 315: # ifdef GEN_TREES_H
! 316: gen_trees_header();
! 317: # endif
! 318: #endif /* defined(GEN_TREES_H) || !defined(STDC) */
! 319: }
! 320:
! 321: /* ===========================================================================
! 322: * Genererate the file trees.h describing the static trees.
! 323: */
! 324: #ifdef GEN_TREES_H
! 325: # ifndef DEBUG
! 326: # include <stdio.h>
! 327: # endif
! 328:
! 329: # define SEPARATOR(i, last, width) \
! 330: ((i) == (last)? "\n};\n\n" : \
! 331: ((i) % (width) == (width)-1 ? ",\n" : ", "))
! 332:
! 333: void gen_trees_header()
! 334: {
! 335: FILE *header = fopen("trees.h", "w");
! 336: int i;
! 337:
! 338: Assert (header != NULL, "Can't open trees.h");
! 339: fprintf(header,
! 340: "/* header created automatically with -DGEN_TREES_H */\n\n");
! 341:
! 342: fprintf(header, "local const ct_data static_ltree[L_CODES+2] = {\n");
! 343: for (i = 0; i < L_CODES+2; i++) {
! 344: fprintf(header, "{{%3u},{%3u}}%s", static_ltree[i].Code,
! 345: static_ltree[i].Len, SEPARATOR(i, L_CODES+1, 5));
! 346: }
! 347:
! 348: fprintf(header, "local const ct_data static_dtree[D_CODES] = {\n");
! 349: for (i = 0; i < D_CODES; i++) {
! 350: fprintf(header, "{{%2u},{%2u}}%s", static_dtree[i].Code,
! 351: static_dtree[i].Len, SEPARATOR(i, D_CODES-1, 5));
! 352: }
! 353:
! 354: fprintf(header, "const uch ZLIB_INTERNAL _dist_code[DIST_CODE_LEN] = {\n");
! 355: for (i = 0; i < DIST_CODE_LEN; i++) {
! 356: fprintf(header, "%2u%s", _dist_code[i],
! 357: SEPARATOR(i, DIST_CODE_LEN-1, 20));
! 358: }
! 359:
! 360: fprintf(header,
! 361: "const uch ZLIB_INTERNAL _length_code[MAX_MATCH-MIN_MATCH+1]= {\n");
! 362: for (i = 0; i < MAX_MATCH-MIN_MATCH+1; i++) {
! 363: fprintf(header, "%2u%s", _length_code[i],
! 364: SEPARATOR(i, MAX_MATCH-MIN_MATCH, 20));
! 365: }
! 366:
! 367: fprintf(header, "local const int base_length[LENGTH_CODES] = {\n");
! 368: for (i = 0; i < LENGTH_CODES; i++) {
! 369: fprintf(header, "%1u%s", base_length[i],
! 370: SEPARATOR(i, LENGTH_CODES-1, 20));
! 371: }
! 372:
! 373: fprintf(header, "local const int base_dist[D_CODES] = {\n");
! 374: for (i = 0; i < D_CODES; i++) {
! 375: fprintf(header, "%5u%s", base_dist[i],
! 376: SEPARATOR(i, D_CODES-1, 10));
! 377: }
! 378:
! 379: fclose(header);
! 380: }
! 381: #endif /* GEN_TREES_H */
! 382:
! 383: /* ===========================================================================
! 384: * Initialize the tree data structures for a new zlib stream.
! 385: */
! 386: void ZLIB_INTERNAL _tr_init(s)
! 387: deflate_state *s;
! 388: {
! 389: tr_static_init();
! 390:
! 391: s->l_desc.dyn_tree = s->dyn_ltree;
! 392: s->l_desc.stat_desc = &static_l_desc;
! 393:
! 394: s->d_desc.dyn_tree = s->dyn_dtree;
! 395: s->d_desc.stat_desc = &static_d_desc;
! 396:
! 397: s->bl_desc.dyn_tree = s->bl_tree;
! 398: s->bl_desc.stat_desc = &static_bl_desc;
! 399:
! 400: s->bi_buf = 0;
! 401: s->bi_valid = 0;
! 402: s->last_eob_len = 8; /* enough lookahead for inflate */
! 403: #ifdef DEBUG
! 404: s->compressed_len = 0L;
! 405: s->bits_sent = 0L;
! 406: #endif
! 407:
! 408: /* Initialize the first block of the first file: */
! 409: init_block(s);
! 410: }
! 411:
! 412: /* ===========================================================================
! 413: * Initialize a new block.
! 414: */
! 415: local void init_block(s)
! 416: deflate_state *s;
! 417: {
! 418: int n; /* iterates over tree elements */
! 419:
! 420: /* Initialize the trees. */
! 421: for (n = 0; n < L_CODES; n++) s->dyn_ltree[n].Freq = 0;
! 422: for (n = 0; n < D_CODES; n++) s->dyn_dtree[n].Freq = 0;
! 423: for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;
! 424:
! 425: s->dyn_ltree[END_BLOCK].Freq = 1;
! 426: s->opt_len = s->static_len = 0L;
! 427: s->last_lit = s->matches = 0;
! 428: }
! 429:
! 430: #define SMALLEST 1
! 431: /* Index within the heap array of least frequent node in the Huffman tree */
! 432:
! 433:
! 434: /* ===========================================================================
! 435: * Remove the smallest element from the heap and recreate the heap with
! 436: * one less element. Updates heap and heap_len.
! 437: */
! 438: #define pqremove(s, tree, top) \
! 439: {\
! 440: top = s->heap[SMALLEST]; \
! 441: s->heap[SMALLEST] = s->heap[s->heap_len--]; \
! 442: pqdownheap(s, tree, SMALLEST); \
! 443: }
! 444:
! 445: /* ===========================================================================
! 446: * Compares to subtrees, using the tree depth as tie breaker when
! 447: * the subtrees have equal frequency. This minimizes the worst case length.
! 448: */
! 449: #define smaller(tree, n, m, depth) \
! 450: (tree[n].Freq < tree[m].Freq || \
! 451: (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
! 452:
! 453: /* ===========================================================================
! 454: * Restore the heap property by moving down the tree starting at node k,
! 455: * exchanging a node with the smallest of its two sons if necessary, stopping
! 456: * when the heap property is re-established (each father smaller than its
! 457: * two sons).
! 458: */
! 459: local void pqdownheap(s, tree, k)
! 460: deflate_state *s;
! 461: ct_data *tree; /* the tree to restore */
! 462: int k; /* node to move down */
! 463: {
! 464: int v = s->heap[k];
! 465: int j = k << 1; /* left son of k */
! 466: while (j <= s->heap_len) {
! 467: /* Set j to the smallest of the two sons: */
! 468: if (j < s->heap_len &&
! 469: smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
! 470: j++;
! 471: }
! 472: /* Exit if v is smaller than both sons */
! 473: if (smaller(tree, v, s->heap[j], s->depth)) break;
! 474:
! 475: /* Exchange v with the smallest son */
! 476: s->heap[k] = s->heap[j]; k = j;
! 477:
! 478: /* And continue down the tree, setting j to the left son of k */
! 479: j <<= 1;
! 480: }
! 481: s->heap[k] = v;
! 482: }
! 483:
! 484: /* ===========================================================================
! 485: * Compute the optimal bit lengths for a tree and update the total bit length
! 486: * for the current block.
! 487: * IN assertion: the fields freq and dad are set, heap[heap_max] and
! 488: * above are the tree nodes sorted by increasing frequency.
! 489: * OUT assertions: the field len is set to the optimal bit length, the
! 490: * array bl_count contains the frequencies for each bit length.
! 491: * The length opt_len is updated; static_len is also updated if stree is
! 492: * not null.
! 493: */
! 494: local void gen_bitlen(s, desc)
! 495: deflate_state *s;
! 496: tree_desc *desc; /* the tree descriptor */
! 497: {
! 498: ct_data *tree = desc->dyn_tree;
! 499: int max_code = desc->max_code;
! 500: const ct_data *stree = desc->stat_desc->static_tree;
! 501: const intf *extra = desc->stat_desc->extra_bits;
! 502: int base = desc->stat_desc->extra_base;
! 503: int max_length = desc->stat_desc->max_length;
! 504: int h; /* heap index */
! 505: int n, m; /* iterate over the tree elements */
! 506: int bits; /* bit length */
! 507: int xbits; /* extra bits */
! 508: ush f; /* frequency */
! 509: int overflow = 0; /* number of elements with bit length too large */
! 510:
! 511: for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;
! 512:
! 513: /* In a first pass, compute the optimal bit lengths (which may
! 514: * overflow in the case of the bit length tree).
! 515: */
! 516: tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */
! 517:
! 518: for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
! 519: n = s->heap[h];
! 520: bits = tree[tree[n].Dad].Len + 1;
! 521: if (bits > max_length) bits = max_length, overflow++;
! 522: tree[n].Len = (ush)bits;
! 523: /* We overwrite tree[n].Dad which is no longer needed */
! 524:
! 525: if (n > max_code) continue; /* not a leaf node */
! 526:
! 527: s->bl_count[bits]++;
! 528: xbits = 0;
! 529: if (n >= base) xbits = extra[n-base];
! 530: f = tree[n].Freq;
! 531: s->opt_len += (ulg)f * (bits + xbits);
! 532: if (stree) s->static_len += (ulg)f * (stree[n].Len + xbits);
! 533: }
! 534: if (overflow == 0) return;
! 535:
! 536: Trace((stderr,"\nbit length overflow\n"));
! 537: /* This happens for example on obj2 and pic of the Calgary corpus */
! 538:
! 539: /* Find the first bit length which could increase: */
! 540: do {
! 541: bits = max_length-1;
! 542: while (s->bl_count[bits] == 0) bits--;
! 543: s->bl_count[bits]--; /* move one leaf down the tree */
! 544: s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
! 545: s->bl_count[max_length]--;
! 546: /* The brother of the overflow item also moves one step up,
! 547: * but this does not affect bl_count[max_length]
! 548: */
! 549: overflow -= 2;
! 550: } while (overflow > 0);
! 551:
! 552: /* Now recompute all bit lengths, scanning in increasing frequency.
! 553: * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
! 554: * lengths instead of fixing only the wrong ones. This idea is taken
! 555: * from 'ar' written by Haruhiko Okumura.)
! 556: */
! 557: for (bits = max_length; bits != 0; bits--) {
! 558: n = s->bl_count[bits];
! 559: while (n != 0) {
! 560: m = s->heap[--h];
! 561: if (m > max_code) continue;
! 562: if ((unsigned) tree[m].Len != (unsigned) bits) {
! 563: Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
! 564: s->opt_len += ((long)bits - (long)tree[m].Len)
! 565: *(long)tree[m].Freq;
! 566: tree[m].Len = (ush)bits;
! 567: }
! 568: n--;
! 569: }
! 570: }
! 571: }
! 572:
! 573: /* ===========================================================================
! 574: * Generate the codes for a given tree and bit counts (which need not be
! 575: * optimal).
! 576: * IN assertion: the array bl_count contains the bit length statistics for
! 577: * the given tree and the field len is set for all tree elements.
! 578: * OUT assertion: the field code is set for all tree elements of non
! 579: * zero code length.
! 580: */
! 581: local void gen_codes (tree, max_code, bl_count)
! 582: ct_data *tree; /* the tree to decorate */
! 583: int max_code; /* largest code with non zero frequency */
! 584: ushf *bl_count; /* number of codes at each bit length */
! 585: {
! 586: ush next_code[MAX_BITS+1]; /* next code value for each bit length */
! 587: ush code = 0; /* running code value */
! 588: int bits; /* bit index */
! 589: int n; /* code index */
! 590:
! 591: /* The distribution counts are first used to generate the code values
! 592: * without bit reversal.
! 593: */
! 594: for (bits = 1; bits <= MAX_BITS; bits++) {
! 595: next_code[bits] = code = (code + bl_count[bits-1]) << 1;
! 596: }
! 597: /* Check that the bit counts in bl_count are consistent. The last code
! 598: * must be all ones.
! 599: */
! 600: Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
! 601: "inconsistent bit counts");
! 602: Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
! 603:
! 604: for (n = 0; n <= max_code; n++) {
! 605: int len = tree[n].Len;
! 606: if (len == 0) continue;
! 607: /* Now reverse the bits */
! 608: tree[n].Code = bi_reverse(next_code[len]++, len);
! 609:
! 610: Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
! 611: n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
! 612: }
! 613: }
! 614:
! 615: /* ===========================================================================
! 616: * Construct one Huffman tree and assigns the code bit strings and lengths.
! 617: * Update the total bit length for the current block.
! 618: * IN assertion: the field freq is set for all tree elements.
! 619: * OUT assertions: the fields len and code are set to the optimal bit length
! 620: * and corresponding code. The length opt_len is updated; static_len is
! 621: * also updated if stree is not null. The field max_code is set.
! 622: */
! 623: local void build_tree(s, desc)
! 624: deflate_state *s;
! 625: tree_desc *desc; /* the tree descriptor */
! 626: {
! 627: ct_data *tree = desc->dyn_tree;
! 628: const ct_data *stree = desc->stat_desc->static_tree;
! 629: int elems = desc->stat_desc->elems;
! 630: int n, m; /* iterate over heap elements */
! 631: int max_code = -1; /* largest code with non zero frequency */
! 632: int node; /* new node being created */
! 633:
! 634: /* Construct the initial heap, with least frequent element in
! 635: * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
! 636: * heap[0] is not used.
! 637: */
! 638: s->heap_len = 0, s->heap_max = HEAP_SIZE;
! 639:
! 640: for (n = 0; n < elems; n++) {
! 641: if (tree[n].Freq != 0) {
! 642: s->heap[++(s->heap_len)] = max_code = n;
! 643: s->depth[n] = 0;
! 644: } else {
! 645: tree[n].Len = 0;
! 646: }
! 647: }
! 648:
! 649: /* The pkzip format requires that at least one distance code exists,
! 650: * and that at least one bit should be sent even if there is only one
! 651: * possible code. So to avoid special checks later on we force at least
! 652: * two codes of non zero frequency.
! 653: */
! 654: while (s->heap_len < 2) {
! 655: node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
! 656: tree[node].Freq = 1;
! 657: s->depth[node] = 0;
! 658: s->opt_len--; if (stree) s->static_len -= stree[node].Len;
! 659: /* node is 0 or 1 so it does not have extra bits */
! 660: }
! 661: desc->max_code = max_code;
! 662:
! 663: /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
! 664: * establish sub-heaps of increasing lengths:
! 665: */
! 666: for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);
! 667:
! 668: /* Construct the Huffman tree by repeatedly combining the least two
! 669: * frequent nodes.
! 670: */
! 671: node = elems; /* next internal node of the tree */
! 672: do {
! 673: pqremove(s, tree, n); /* n = node of least frequency */
! 674: m = s->heap[SMALLEST]; /* m = node of next least frequency */
! 675:
! 676: s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
! 677: s->heap[--(s->heap_max)] = m;
! 678:
! 679: /* Create a new node father of n and m */
! 680: tree[node].Freq = tree[n].Freq + tree[m].Freq;
! 681: s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
! 682: s->depth[n] : s->depth[m]) + 1);
! 683: tree[n].Dad = tree[m].Dad = (ush)node;
! 684: #ifdef DUMP_BL_TREE
! 685: if (tree == s->bl_tree) {
! 686: fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
! 687: node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
! 688: }
! 689: #endif
! 690: /* and insert the new node in the heap */
! 691: s->heap[SMALLEST] = node++;
! 692: pqdownheap(s, tree, SMALLEST);
! 693:
! 694: } while (s->heap_len >= 2);
! 695:
! 696: s->heap[--(s->heap_max)] = s->heap[SMALLEST];
! 697:
! 698: /* At this point, the fields freq and dad are set. We can now
! 699: * generate the bit lengths.
! 700: */
! 701: gen_bitlen(s, (tree_desc *)desc);
! 702:
! 703: /* The field len is now set, we can generate the bit codes */
! 704: gen_codes ((ct_data *)tree, max_code, s->bl_count);
! 705: }
! 706:
! 707: /* ===========================================================================
! 708: * Scan a literal or distance tree to determine the frequencies of the codes
! 709: * in the bit length tree.
! 710: */
! 711: local void scan_tree (s, tree, max_code)
! 712: deflate_state *s;
! 713: ct_data *tree; /* the tree to be scanned */
! 714: int max_code; /* and its largest code of non zero frequency */
! 715: {
! 716: int n; /* iterates over all tree elements */
! 717: int prevlen = -1; /* last emitted length */
! 718: int curlen; /* length of current code */
! 719: int nextlen = tree[0].Len; /* length of next code */
! 720: int count = 0; /* repeat count of the current code */
! 721: int max_count = 7; /* max repeat count */
! 722: int min_count = 4; /* min repeat count */
! 723:
! 724: if (nextlen == 0) max_count = 138, min_count = 3;
! 725: tree[max_code+1].Len = (ush)0xffff; /* guard */
! 726:
! 727: for (n = 0; n <= max_code; n++) {
! 728: curlen = nextlen; nextlen = tree[n+1].Len;
! 729: if (++count < max_count && curlen == nextlen) {
! 730: continue;
! 731: } else if (count < min_count) {
! 732: s->bl_tree[curlen].Freq += count;
! 733: } else if (curlen != 0) {
! 734: if (curlen != prevlen) s->bl_tree[curlen].Freq++;
! 735: s->bl_tree[REP_3_6].Freq++;
! 736: } else if (count <= 10) {
! 737: s->bl_tree[REPZ_3_10].Freq++;
! 738: } else {
! 739: s->bl_tree[REPZ_11_138].Freq++;
! 740: }
! 741: count = 0; prevlen = curlen;
! 742: if (nextlen == 0) {
! 743: max_count = 138, min_count = 3;
! 744: } else if (curlen == nextlen) {
! 745: max_count = 6, min_count = 3;
! 746: } else {
! 747: max_count = 7, min_count = 4;
! 748: }
! 749: }
! 750: }
! 751:
! 752: /* ===========================================================================
! 753: * Send a literal or distance tree in compressed form, using the codes in
! 754: * bl_tree.
! 755: */
! 756: local void send_tree (s, tree, max_code)
! 757: deflate_state *s;
! 758: ct_data *tree; /* the tree to be scanned */
! 759: int max_code; /* and its largest code of non zero frequency */
! 760: {
! 761: int n; /* iterates over all tree elements */
! 762: int prevlen = -1; /* last emitted length */
! 763: int curlen; /* length of current code */
! 764: int nextlen = tree[0].Len; /* length of next code */
! 765: int count = 0; /* repeat count of the current code */
! 766: int max_count = 7; /* max repeat count */
! 767: int min_count = 4; /* min repeat count */
! 768:
! 769: /* tree[max_code+1].Len = -1; */ /* guard already set */
! 770: if (nextlen == 0) max_count = 138, min_count = 3;
! 771:
! 772: for (n = 0; n <= max_code; n++) {
! 773: curlen = nextlen; nextlen = tree[n+1].Len;
! 774: if (++count < max_count && curlen == nextlen) {
! 775: continue;
! 776: } else if (count < min_count) {
! 777: do { send_code(s, curlen, s->bl_tree); } while (--count != 0);
! 778:
! 779: } else if (curlen != 0) {
! 780: if (curlen != prevlen) {
! 781: send_code(s, curlen, s->bl_tree); count--;
! 782: }
! 783: Assert(count >= 3 && count <= 6, " 3_6?");
! 784: send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);
! 785:
! 786: } else if (count <= 10) {
! 787: send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);
! 788:
! 789: } else {
! 790: send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
! 791: }
! 792: count = 0; prevlen = curlen;
! 793: if (nextlen == 0) {
! 794: max_count = 138, min_count = 3;
! 795: } else if (curlen == nextlen) {
! 796: max_count = 6, min_count = 3;
! 797: } else {
! 798: max_count = 7, min_count = 4;
! 799: }
! 800: }
! 801: }
! 802:
! 803: /* ===========================================================================
! 804: * Construct the Huffman tree for the bit lengths and return the index in
! 805: * bl_order of the last bit length code to send.
! 806: */
! 807: local int build_bl_tree(s)
! 808: deflate_state *s;
! 809: {
! 810: int max_blindex; /* index of last bit length code of non zero freq */
! 811:
! 812: /* Determine the bit length frequencies for literal and distance trees */
! 813: scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
! 814: scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);
! 815:
! 816: /* Build the bit length tree: */
! 817: build_tree(s, (tree_desc *)(&(s->bl_desc)));
! 818: /* opt_len now includes the length of the tree representations, except
! 819: * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
! 820: */
! 821:
! 822: /* Determine the number of bit length codes to send. The pkzip format
! 823: * requires that at least 4 bit length codes be sent. (appnote.txt says
! 824: * 3 but the actual value used is 4.)
! 825: */
! 826: for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
! 827: if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
! 828: }
! 829: /* Update opt_len to include the bit length tree and counts */
! 830: s->opt_len += 3*(max_blindex+1) + 5+5+4;
! 831: Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
! 832: s->opt_len, s->static_len));
! 833:
! 834: return max_blindex;
! 835: }
! 836:
! 837: /* ===========================================================================
! 838: * Send the header for a block using dynamic Huffman trees: the counts, the
! 839: * lengths of the bit length codes, the literal tree and the distance tree.
! 840: * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
! 841: */
! 842: local void send_all_trees(s, lcodes, dcodes, blcodes)
! 843: deflate_state *s;
! 844: int lcodes, dcodes, blcodes; /* number of codes for each tree */
! 845: {
! 846: int rank; /* index in bl_order */
! 847:
! 848: Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
! 849: Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
! 850: "too many codes");
! 851: Tracev((stderr, "\nbl counts: "));
! 852: send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
! 853: send_bits(s, dcodes-1, 5);
! 854: send_bits(s, blcodes-4, 4); /* not -3 as stated in appnote.txt */
! 855: for (rank = 0; rank < blcodes; rank++) {
! 856: Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
! 857: send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
! 858: }
! 859: Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
! 860:
! 861: send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
! 862: Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
! 863:
! 864: send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
! 865: Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
! 866: }
! 867:
! 868: /* ===========================================================================
! 869: * Send a stored block
! 870: */
! 871: void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
! 872: deflate_state *s;
! 873: charf *buf; /* input block */
! 874: ulg stored_len; /* length of input block */
! 875: int last; /* one if this is the last block for a file */
! 876: {
! 877: send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */
! 878: #ifdef DEBUG
! 879: s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
! 880: s->compressed_len += (stored_len + 4) << 3;
! 881: #endif
! 882: copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
! 883: }
! 884:
! 885: /* ===========================================================================
! 886: * Send one empty static block to give enough lookahead for inflate.
! 887: * This takes 10 bits, of which 7 may remain in the bit buffer.
! 888: * The current inflate code requires 9 bits of lookahead. If the
! 889: * last two codes for the previous block (real code plus EOB) were coded
! 890: * on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
! 891: * the last real code. In this case we send two empty static blocks instead
! 892: * of one. (There are no problems if the previous block is stored or fixed.)
! 893: * To simplify the code, we assume the worst case of last real code encoded
! 894: * on one bit only.
! 895: */
! 896: void ZLIB_INTERNAL _tr_align(s)
! 897: deflate_state *s;
! 898: {
! 899: send_bits(s, STATIC_TREES<<1, 3);
! 900: send_code(s, END_BLOCK, static_ltree);
! 901: #ifdef DEBUG
! 902: s->compressed_len += 10L; /* 3 for block type, 7 for EOB */
! 903: #endif
! 904: bi_flush(s);
! 905: /* Of the 10 bits for the empty block, we have already sent
! 906: * (10 - bi_valid) bits. The lookahead for the last real code (before
! 907: * the EOB of the previous block) was thus at least one plus the length
! 908: * of the EOB plus what we have just sent of the empty static block.
! 909: */
! 910: if (1 + s->last_eob_len + 10 - s->bi_valid < 9) {
! 911: send_bits(s, STATIC_TREES<<1, 3);
! 912: send_code(s, END_BLOCK, static_ltree);
! 913: #ifdef DEBUG
! 914: s->compressed_len += 10L;
! 915: #endif
! 916: bi_flush(s);
! 917: }
! 918: s->last_eob_len = 7;
! 919: }
! 920:
! 921: /* ===========================================================================
! 922: * Determine the best encoding for the current block: dynamic trees, static
! 923: * trees or store, and output the encoded block to the zip file.
! 924: */
! 925: void ZLIB_INTERNAL _tr_flush_block(s, buf, stored_len, last)
! 926: deflate_state *s;
! 927: charf *buf; /* input block, or NULL if too old */
! 928: ulg stored_len; /* length of input block */
! 929: int last; /* one if this is the last block for a file */
! 930: {
! 931: ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
! 932: int max_blindex = 0; /* index of last bit length code of non zero freq */
! 933:
! 934: /* Build the Huffman trees unless a stored block is forced */
! 935: if (s->level > 0) {
! 936:
! 937: /* Check if the file is binary or text */
! 938: if (s->strm->data_type == Z_UNKNOWN)
! 939: s->strm->data_type = detect_data_type(s);
! 940:
! 941: /* Construct the literal and distance trees */
! 942: build_tree(s, (tree_desc *)(&(s->l_desc)));
! 943: Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
! 944: s->static_len));
! 945:
! 946: build_tree(s, (tree_desc *)(&(s->d_desc)));
! 947: Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
! 948: s->static_len));
! 949: /* At this point, opt_len and static_len are the total bit lengths of
! 950: * the compressed block data, excluding the tree representations.
! 951: */
! 952:
! 953: /* Build the bit length tree for the above two trees, and get the index
! 954: * in bl_order of the last bit length code to send.
! 955: */
! 956: max_blindex = build_bl_tree(s);
! 957:
! 958: /* Determine the best encoding. Compute the block lengths in bytes. */
! 959: opt_lenb = (s->opt_len+3+7)>>3;
! 960: static_lenb = (s->static_len+3+7)>>3;
! 961:
! 962: Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
! 963: opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
! 964: s->last_lit));
! 965:
! 966: if (static_lenb <= opt_lenb) opt_lenb = static_lenb;
! 967:
! 968: } else {
! 969: Assert(buf != (char*)0, "lost buf");
! 970: opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
! 971: }
! 972:
! 973: #ifdef FORCE_STORED
! 974: if (buf != (char*)0) { /* force stored block */
! 975: #else
! 976: if (stored_len+4 <= opt_lenb && buf != (char*)0) {
! 977: /* 4: two words for the lengths */
! 978: #endif
! 979: /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
! 980: * Otherwise we can't have processed more than WSIZE input bytes since
! 981: * the last block flush, because compression would have been
! 982: * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
! 983: * transform a block into a stored block.
! 984: */
! 985: _tr_stored_block(s, buf, stored_len, last);
! 986:
! 987: #ifdef FORCE_STATIC
! 988: } else if (static_lenb >= 0) { /* force static trees */
! 989: #else
! 990: } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
! 991: #endif
! 992: send_bits(s, (STATIC_TREES<<1)+last, 3);
! 993: compress_block(s, (ct_data *)static_ltree, (ct_data *)static_dtree);
! 994: #ifdef DEBUG
! 995: s->compressed_len += 3 + s->static_len;
! 996: #endif
! 997: } else {
! 998: send_bits(s, (DYN_TREES<<1)+last, 3);
! 999: send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
! 1000: max_blindex+1);
! 1001: compress_block(s, (ct_data *)s->dyn_ltree, (ct_data *)s->dyn_dtree);
! 1002: #ifdef DEBUG
! 1003: s->compressed_len += 3 + s->opt_len;
! 1004: #endif
! 1005: }
! 1006: Assert (s->compressed_len == s->bits_sent, "bad compressed size");
! 1007: /* The above check is made mod 2^32, for files larger than 512 MB
! 1008: * and uLong implemented on 32 bits.
! 1009: */
! 1010: init_block(s);
! 1011:
! 1012: if (last) {
! 1013: bi_windup(s);
! 1014: #ifdef DEBUG
! 1015: s->compressed_len += 7; /* align on byte boundary */
! 1016: #endif
! 1017: }
! 1018: Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
! 1019: s->compressed_len-7*last));
! 1020: }
! 1021:
! 1022: /* ===========================================================================
! 1023: * Save the match info and tally the frequency counts. Return true if
! 1024: * the current block must be flushed.
! 1025: */
! 1026: int ZLIB_INTERNAL _tr_tally (s, dist, lc)
! 1027: deflate_state *s;
! 1028: unsigned dist; /* distance of matched string */
! 1029: unsigned lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */
! 1030: {
! 1031: s->d_buf[s->last_lit] = (ush)dist;
! 1032: s->l_buf[s->last_lit++] = (uch)lc;
! 1033: if (dist == 0) {
! 1034: /* lc is the unmatched char */
! 1035: s->dyn_ltree[lc].Freq++;
! 1036: } else {
! 1037: s->matches++;
! 1038: /* Here, lc is the match length - MIN_MATCH */
! 1039: dist--; /* dist = match distance - 1 */
! 1040: Assert((ush)dist < (ush)MAX_DIST(s) &&
! 1041: (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
! 1042: (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
! 1043:
! 1044: s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
! 1045: s->dyn_dtree[d_code(dist)].Freq++;
! 1046: }
! 1047:
! 1048: #ifdef TRUNCATE_BLOCK
! 1049: /* Try to guess if it is profitable to stop the current block here */
! 1050: if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
! 1051: /* Compute an upper bound for the compressed length */
! 1052: ulg out_length = (ulg)s->last_lit*8L;
! 1053: ulg in_length = (ulg)((long)s->strstart - s->block_start);
! 1054: int dcode;
! 1055: for (dcode = 0; dcode < D_CODES; dcode++) {
! 1056: out_length += (ulg)s->dyn_dtree[dcode].Freq *
! 1057: (5L+extra_dbits[dcode]);
! 1058: }
! 1059: out_length >>= 3;
! 1060: Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
! 1061: s->last_lit, in_length, out_length,
! 1062: 100L - out_length*100L/in_length));
! 1063: if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
! 1064: }
! 1065: #endif
! 1066: return (s->last_lit == s->lit_bufsize-1);
! 1067: /* We avoid equality with lit_bufsize because of wraparound at 64K
! 1068: * on 16 bit machines and because stored blocks are restricted to
! 1069: * 64K-1 bytes.
! 1070: */
! 1071: }
! 1072:
! 1073: /* ===========================================================================
! 1074: * Send the block data compressed using the given Huffman trees
! 1075: */
! 1076: local void compress_block(s, ltree, dtree)
! 1077: deflate_state *s;
! 1078: ct_data *ltree; /* literal tree */
! 1079: ct_data *dtree; /* distance tree */
! 1080: {
! 1081: unsigned dist; /* distance of matched string */
! 1082: int lc; /* match length or unmatched char (if dist == 0) */
! 1083: unsigned lx = 0; /* running index in l_buf */
! 1084: unsigned code; /* the code to send */
! 1085: int extra; /* number of extra bits to send */
! 1086:
! 1087: if (s->last_lit != 0) do {
! 1088: dist = s->d_buf[lx];
! 1089: lc = s->l_buf[lx++];
! 1090: if (dist == 0) {
! 1091: send_code(s, lc, ltree); /* send a literal byte */
! 1092: Tracecv(isgraph(lc), (stderr," '%c' ", lc));
! 1093: } else {
! 1094: /* Here, lc is the match length - MIN_MATCH */
! 1095: code = _length_code[lc];
! 1096: send_code(s, code+LITERALS+1, ltree); /* send the length code */
! 1097: extra = extra_lbits[code];
! 1098: if (extra != 0) {
! 1099: lc -= base_length[code];
! 1100: send_bits(s, lc, extra); /* send the extra length bits */
! 1101: }
! 1102: dist--; /* dist is now the match distance - 1 */
! 1103: code = d_code(dist);
! 1104: Assert (code < D_CODES, "bad d_code");
! 1105:
! 1106: send_code(s, code, dtree); /* send the distance code */
! 1107: extra = extra_dbits[code];
! 1108: if (extra != 0) {
! 1109: dist -= base_dist[code];
! 1110: send_bits(s, dist, extra); /* send the extra distance bits */
! 1111: }
! 1112: } /* literal or match pair ? */
! 1113:
! 1114: /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
! 1115: Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
! 1116: "pendingBuf overflow");
! 1117:
! 1118: } while (lx < s->last_lit);
! 1119:
! 1120: send_code(s, END_BLOCK, ltree);
! 1121: s->last_eob_len = ltree[END_BLOCK].Len;
! 1122: }
! 1123:
! 1124: /* ===========================================================================
! 1125: * Check if the data type is TEXT or BINARY, using the following algorithm:
! 1126: * - TEXT if the two conditions below are satisfied:
! 1127: * a) There are no non-portable control characters belonging to the
! 1128: * "black list" (0..6, 14..25, 28..31).
! 1129: * b) There is at least one printable character belonging to the
! 1130: * "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
! 1131: * - BINARY otherwise.
! 1132: * - The following partially-portable control characters form a
! 1133: * "gray list" that is ignored in this detection algorithm:
! 1134: * (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
! 1135: * IN assertion: the fields Freq of dyn_ltree are set.
! 1136: */
! 1137: local int detect_data_type(s)
! 1138: deflate_state *s;
! 1139: {
! 1140: /* black_mask is the bit mask of black-listed bytes
! 1141: * set bits 0..6, 14..25, and 28..31
! 1142: * 0xf3ffc07f = binary 11110011111111111100000001111111
! 1143: */
! 1144: unsigned long black_mask = 0xf3ffc07fUL;
! 1145: int n;
! 1146:
! 1147: /* Check for non-textual ("black-listed") bytes. */
! 1148: for (n = 0; n <= 31; n++, black_mask >>= 1)
! 1149: if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
! 1150: return Z_BINARY;
! 1151:
! 1152: /* Check for textual ("white-listed") bytes. */
! 1153: if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
! 1154: || s->dyn_ltree[13].Freq != 0)
! 1155: return Z_TEXT;
! 1156: for (n = 32; n < LITERALS; n++)
! 1157: if (s->dyn_ltree[n].Freq != 0)
! 1158: return Z_TEXT;
! 1159:
! 1160: /* There are no "black-listed" or "white-listed" bytes:
! 1161: * this stream either is empty or has tolerated ("gray-listed") bytes only.
! 1162: */
! 1163: return Z_BINARY;
! 1164: }
! 1165:
! 1166: /* ===========================================================================
! 1167: * Reverse the first len bits of a code, using straightforward code (a faster
! 1168: * method would use a table)
! 1169: * IN assertion: 1 <= len <= 15
! 1170: */
! 1171: local unsigned bi_reverse(code, len)
! 1172: unsigned code; /* the value to invert */
! 1173: int len; /* its bit length */
! 1174: {
! 1175: register unsigned res = 0;
! 1176: do {
! 1177: res |= code & 1;
! 1178: code >>= 1, res <<= 1;
! 1179: } while (--len > 0);
! 1180: return res >> 1;
! 1181: }
! 1182:
! 1183: /* ===========================================================================
! 1184: * Flush the bit buffer, keeping at most 7 bits in it.
! 1185: */
! 1186: local void bi_flush(s)
! 1187: deflate_state *s;
! 1188: {
! 1189: if (s->bi_valid == 16) {
! 1190: put_short(s, s->bi_buf);
! 1191: s->bi_buf = 0;
! 1192: s->bi_valid = 0;
! 1193: } else if (s->bi_valid >= 8) {
! 1194: put_byte(s, (Byte)s->bi_buf);
! 1195: s->bi_buf >>= 8;
! 1196: s->bi_valid -= 8;
! 1197: }
! 1198: }
! 1199:
! 1200: /* ===========================================================================
! 1201: * Flush the bit buffer and align the output on a byte boundary
! 1202: */
! 1203: local void bi_windup(s)
! 1204: deflate_state *s;
! 1205: {
! 1206: if (s->bi_valid > 8) {
! 1207: put_short(s, s->bi_buf);
! 1208: } else if (s->bi_valid > 0) {
! 1209: put_byte(s, (Byte)s->bi_buf);
! 1210: }
! 1211: s->bi_buf = 0;
! 1212: s->bi_valid = 0;
! 1213: #ifdef DEBUG
! 1214: s->bits_sent = (s->bits_sent+7) & ~7;
! 1215: #endif
! 1216: }
! 1217:
! 1218: /* ===========================================================================
! 1219: * Copy a stored block, storing first the length and its
! 1220: * one's complement if requested.
! 1221: */
! 1222: local void copy_block(s, buf, len, header)
! 1223: deflate_state *s;
! 1224: charf *buf; /* the input data */
! 1225: unsigned len; /* its length */
! 1226: int header; /* true if block header must be written */
! 1227: {
! 1228: bi_windup(s); /* align on byte boundary */
! 1229: s->last_eob_len = 8; /* enough lookahead for inflate */
! 1230:
! 1231: if (header) {
! 1232: put_short(s, (ush)len);
! 1233: put_short(s, (ush)~len);
! 1234: #ifdef DEBUG
! 1235: s->bits_sent += 2*16;
! 1236: #endif
! 1237: }
! 1238: #ifdef DEBUG
! 1239: s->bits_sent += (ulg)len<<3;
! 1240: #endif
! 1241: while (len--) {
! 1242: put_byte(s, *buf++);
! 1243: }
! 1244: }
FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>
![[BACK]](/icons/cvsweb/back.gif){kind=icon}
Return to trees.c CVS log ![[TXT]](/icons/cvsweb/text.gif){kind=icon}
![[DIR]](/icons/cvsweb/dir.gif){kind=icon}
Up to [ELWIX - Embedded LightWeight unIX -] / embedaddon / sudo / zlib