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1.1.1.4 ! root 1: /* ! 2: ! 3: Copyright (C) 1990-1992 Mark Adler, Richard B. Wales, Jean-loup Gailly, ! 4: Kai Uwe Rommel and Igor Mandrichenko. ! 5: Permission is granted to any individual or institution to use, copy, or ! 6: redistribute this software so long as all of the original files are included ! 7: unmodified, that it is not sold for profit, and that this copyright notice ! 8: is retained. ! 9: ! 10: */ ! 11: ! 12: /* ! 13: * trees.c by Jean-loup Gailly ! 14: * ! 15: * This is a new version of im_ctree.c originally written by Richard B. Wales ! 16: * for the defunct implosion method. ! 17: * ! 18: * PURPOSE ! 19: * ! 20: * Encode various sets of source values using variable-length ! 21: * binary code trees. ! 22: * ! 23: * DISCUSSION ! 24: * ! 25: * The PKZIP "deflation" process uses several Huffman trees. The more ! 26: * common source values are represented by shorter bit sequences. ! 27: * ! 28: * Each code tree is stored in the ZIP file in a compressed form ! 29: * which is itself a Huffman encoding of the lengths of ! 30: * all the code strings (in ascending order by source values). ! 31: * The actual code strings are reconstructed from the lengths in ! 32: * the UNZIP process, as described in the "application note" ! 33: * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program. ! 34: * ! 35: * REFERENCES ! 36: * ! 37: * Lynch, Thomas J. ! 38: * Data Compression: Techniques and Applications, pp. 53-55. ! 39: * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7. ! 40: * ! 41: * Storer, James A. ! 42: * Data Compression: Methods and Theory, pp. 49-50. ! 43: * Computer Science Press, 1988. ISBN 0-7167-8156-5. ! 44: * ! 45: * Sedgewick, R. ! 46: * Algorithms, p290. ! 47: * Addison-Wesley, 1983. ISBN 0-201-06672-6. ! 48: * ! 49: * INTERFACE ! 50: * ! 51: * void ct_init (ush *attr, int *method) ! 52: * Allocate the match buffer, initialize the various tables and save ! 53: * the location of the internal file attribute (ascii/binary) and ! 54: * method (DEFLATE/STORE) ! 55: * ! 56: * void ct_tally (int dist, int lc); ! 57: * Save the match info and tally the frequency counts. ! 58: * ! 59: * long flush_block (char *buf, ulg stored_len, int eof) ! 60: * Determine the best encoding for the current block: dynamic trees, ! 61: * static trees or store, and output the encoded block to the zip ! 62: * file. Returns the total compressed length for the file so far. ! 63: * ! 64: */ ! 65: ! 66: #include <ctype.h> ! 67: #include "zip.h" ! 68: ! 69: /* =========================================================================== ! 70: * Constants ! 71: */ ! 72: ! 73: #define MAX_BITS 15 ! 74: /* All codes must not exceed MAX_BITS bits */ ! 75: ! 76: #define MAX_BL_BITS 7 ! 77: /* Bit length codes must not exceed MAX_BL_BITS bits */ ! 78: ! 79: #define LENGTH_CODES 29 ! 80: /* number of length codes, not counting the special END_BLOCK code */ ! 81: ! 82: #define LITERALS 256 ! 83: /* number of literal bytes 0..255 */ ! 84: ! 85: #define END_BLOCK 256 ! 86: /* end of block literal code */ ! 87: ! 88: #define L_CODES (LITERALS+1+LENGTH_CODES) ! 89: /* number of Literal or Length codes, including the END_BLOCK code */ ! 90: ! 91: #define D_CODES 30 ! 92: /* number of distance codes */ ! 93: ! 94: #define BL_CODES 19 ! 95: /* number of codes used to transfer the bit lengths */ ! 96: ! 97: ! 98: local int near extra_lbits[LENGTH_CODES] /* extra bits for each length code */ ! 99: = {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}; ! 100: ! 101: local int near extra_dbits[D_CODES] /* extra bits for each distance code */ ! 102: = {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}; ! 103: ! 104: local int near extra_blbits[BL_CODES]/* extra bits for each bit length code */ ! 105: = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; ! 106: ! 107: #define STORED_BLOCK 0 ! 108: #define STATIC_TREES 1 ! 109: #define DYN_TREES 2 ! 110: /* The three kinds of block type */ ! 111: ! 112: #ifndef LIT_BUFSIZE ! 113: # ifdef SMALL_MEM ! 114: # define LIT_BUFSIZE 0x2000 ! 115: # else ! 116: # ifdef MEDIUM_MEM ! 117: # define LIT_BUFSIZE 0x4000 ! 118: # else ! 119: # define LIT_BUFSIZE 0x8000 ! 120: # endif ! 121: # endif ! 122: #endif ! 123: #define DIST_BUFSIZE LIT_BUFSIZE ! 124: /* Sizes of match buffers for literals/lengths and distances. There are ! 125: * 4 reasons for limiting LIT_BUFSIZE to 64K: ! 126: * - frequencies can be kept in 16 bit counters ! 127: * - if compression is not successful for the first block, all input data is ! 128: * still in the window so we can still emit a stored block even when input ! 129: * comes from standard input. (This can also be done for all blocks if ! 130: * LIT_BUFSIZE is not greater than 32K.) ! 131: * - if compression is not successful for a file smaller than 64K, we can ! 132: * even emit a stored file instead of a stored block (saving 5 bytes). ! 133: * - creating new Huffman trees less frequently may not provide fast ! 134: * adaptation to changes in the input data statistics. (Take for ! 135: * example a binary file with poorly compressible code followed by ! 136: * a highly compressible string table.) Smaller buffer sizes give ! 137: * fast adaptation but have of course the overhead of transmitting trees ! 138: * more frequently. ! 139: * - I can't count above 4 ! 140: * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save ! 141: * memory at the expense of compression). Some optimizations would be possible ! 142: * if we rely on DIST_BUFSIZE == LIT_BUFSIZE. ! 143: */ ! 144: ! 145: #define REP_3_6 16 ! 146: /* repeat previous bit length 3-6 times (2 bits of repeat count) */ ! 147: ! 148: #define REPZ_3_10 17 ! 149: /* repeat a zero length 3-10 times (3 bits of repeat count) */ ! 150: ! 151: #define REPZ_11_138 18 ! 152: /* repeat a zero length 11-138 times (7 bits of repeat count) */ ! 153: ! 154: /* =========================================================================== ! 155: * Local data ! 156: */ ! 157: ! 158: /* Data structure describing a single value and its code string. */ ! 159: typedef struct ct_data { ! 160: union { ! 161: ush freq; /* frequency count */ ! 162: ush code; /* bit string */ ! 163: } fc; ! 164: union { ! 165: ush dad; /* father node in Huffman tree */ ! 166: ush len; /* length of bit string */ ! 167: } dl; ! 168: } ct_data; ! 169: ! 170: #define Freq fc.freq ! 171: #define Code fc.code ! 172: #define Dad dl.dad ! 173: #define Len dl.len ! 174: ! 175: #define HEAP_SIZE (2*L_CODES+1) ! 176: /* maximum heap size */ ! 177: ! 178: local ct_data near dyn_ltree[HEAP_SIZE]; /* literal and length tree */ ! 179: local ct_data near dyn_dtree[2*D_CODES+1]; /* distance tree */ ! 180: ! 181: local ct_data near static_ltree[L_CODES+2]; ! 182: /* The static literal tree. Since the bit lengths are imposed, there is no ! 183: * need for the L_CODES extra codes used during heap construction. However ! 184: * The codes 286 and 287 are needed to build a canonical tree (see ct_init ! 185: * below). ! 186: */ ! 187: ! 188: local ct_data near static_dtree[D_CODES]; ! 189: /* The static distance tree. (Actually a trivial tree since all codes use ! 190: * 5 bits.) ! 191: */ ! 192: ! 193: local ct_data near bl_tree[2*BL_CODES+1]; ! 194: /* Huffman tree for the bit lengths */ ! 195: ! 196: typedef struct tree_desc { ! 197: ct_data near *dyn_tree; /* the dynamic tree */ ! 198: ct_data near *static_tree; /* corresponding static tree or NULL */ ! 199: int near *extra_bits; /* extra bits for each code or NULL */ ! 200: int extra_base; /* base index for extra_bits */ ! 201: int elems; /* max number of elements in the tree */ ! 202: int max_length; /* max bit length for the codes */ ! 203: int max_code; /* largest code with non zero frequency */ ! 204: } tree_desc; ! 205: ! 206: local tree_desc near l_desc = ! 207: {dyn_ltree, static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS, 0}; ! 208: ! 209: local tree_desc near d_desc = ! 210: {dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0}; ! 211: ! 212: local tree_desc near bl_desc = ! 213: {bl_tree, NULL, extra_blbits, 0, BL_CODES, MAX_BL_BITS, 0}; ! 214: ! 215: ! 216: local ush near bl_count[MAX_BITS+1]; ! 217: /* number of codes at each bit length for an optimal tree */ ! 218: ! 219: local uch near bl_order[BL_CODES] ! 220: = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; ! 221: /* The lengths of the bit length codes are sent in order of decreasing ! 222: * probability, to avoid transmitting the lengths for unused bit length codes. ! 223: */ ! 224: ! 225: local int near heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ ! 226: local int heap_len; /* number of elements in the heap */ ! 227: local int heap_max; /* element of largest frequency */ ! 228: /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. ! 229: * The same heap array is used to build all trees. ! 230: */ ! 231: ! 232: local uch near depth[2*L_CODES+1]; ! 233: /* Depth of each subtree used as tie breaker for trees of equal frequency */ ! 234: ! 235: local uch length_code[MAX_MATCH-MIN_MATCH+1]; ! 236: /* length code for each normalized match length (0 == MIN_MATCH) */ ! 237: ! 238: local uch dist_code[512]; ! 239: /* distance codes. The first 256 values correspond to the distances ! 240: * 3 .. 258, the last 256 values correspond to the top 8 bits of ! 241: * the 15 bit distances. ! 242: */ ! 243: ! 244: local int near base_length[LENGTH_CODES]; ! 245: /* First normalized length for each code (0 = MIN_MATCH) */ ! 246: ! 247: local int near base_dist[D_CODES]; ! 248: /* First normalized distance for each code (0 = distance of 1) */ ! 249: ! 250: #ifndef DYN_ALLOC ! 251: local uch far l_buf[LIT_BUFSIZE]; /* buffer for literals/lengths */ ! 252: local ush far d_buf[DIST_BUFSIZE]; /* buffer for distances */ ! 253: #else ! 254: local uch far *l_buf; ! 255: local ush far *d_buf; ! 256: #endif ! 257: ! 258: local uch near flag_buf[(LIT_BUFSIZE/8)]; ! 259: /* flag_buf is a bit array distinguishing literals from lengths in ! 260: * l_buf, and thus indicating the presence or absence of a distance. ! 261: */ ! 262: ! 263: local unsigned last_lit; /* running index in l_buf */ ! 264: local unsigned last_dist; /* running index in d_buf */ ! 265: local unsigned last_flags; /* running index in flag_buf */ ! 266: local uch flags; /* current flags not yet saved in flag_buf */ ! 267: local uch flag_bit; /* current bit used in flags */ ! 268: /* bits are filled in flags starting at bit 0 (least significant). ! 269: * Note: these flags are overkill in the current code since we don't ! 270: * take advantage of DIST_BUFSIZE == LIT_BUFSIZE. ! 271: */ ! 272: ! 273: local ulg opt_len; /* bit length of current block with optimal trees */ ! 274: local ulg static_len; /* bit length of current block with static trees */ ! 275: ! 276: local ulg compressed_len; /* total bit length of compressed file */ ! 277: ! 278: local ulg input_len; /* total byte length of input file */ ! 279: /* input_len is for debugging only since we can get it by other means. */ ! 280: ! 281: static ush *file_type; /* pointer to UNKNOWN, BINARY or ASCII */ ! 282: static int *file_method; /* pointer to DEFLATE or STORE */ ! 283: ! 284: #ifdef DEBUG ! 285: extern ulg bits_sent; /* bit length of the compressed data */ ! 286: extern ulg isize; /* byte length of input file */ ! 287: #endif ! 288: ! 289: extern long block_start; /* window offset of current block */ ! 290: extern unsigned near strstart; /* window offset of current string */ ! 291: ! 292: /* =========================================================================== ! 293: * Local (static) routines in this file. ! 294: */ ! 295: ! 296: local void init_block OF((void)); ! 297: local void pqdownheap OF((ct_data near *tree, int k)); ! 298: local void gen_bitlen OF((tree_desc near *desc)); ! 299: local void gen_codes OF((ct_data near *tree, int max_code)); ! 300: local void build_tree OF((tree_desc near *desc)); ! 301: local void scan_tree OF((ct_data near *tree, int max_code)); ! 302: local void send_tree OF((ct_data near *tree, int max_code)); ! 303: local int build_bl_tree OF((void)); ! 304: local void send_all_trees OF((int lcodes, int dcodes, int blcodes)); ! 305: local void compress_block OF((ct_data near *ltree, ct_data near *dtree)); ! 306: local void set_file_type OF((void)); ! 307: ! 308: ! 309: #ifndef DEBUG ! 310: # define send_code(c, tree) send_bits(tree[c].Code, tree[c].Len) ! 311: /* Send a code of the given tree. c and tree must not have side effects */ ! 312: ! 313: #else /* DEBUG */ ! 314: # define send_code(c, tree) \ ! 315: { if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \ ! 316: send_bits(tree[c].Code, tree[c].Len); } ! 317: #endif ! 318: ! 319: #define d_code(dist) \ ! 320: ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)]) ! 321: /* Mapping from a distance to a distance code. dist is the distance - 1 and ! 322: * must not have side effects. dist_code[256] and dist_code[257] are never ! 323: * used. ! 324: */ ! 325: ! 326: #define MAX(a,b) (a >= b ? a : b) ! 327: /* the arguments must not have side effects */ ! 328: ! 329: /* =========================================================================== ! 330: * Allocate the match buffer, initialize the various tables and save the ! 331: * location of the internal file attribute (ascii/binary) and method ! 332: * (DEFLATE/STORE). ! 333: */ ! 334: void ct_init(attr, Method) ! 335: ush *attr; /* pointer to internal file attribute */ ! 336: int *Method; /* pointer to compression method */ ! 337: { ! 338: int n; /* iterates over tree elements */ ! 339: int bits; /* bit counter */ ! 340: int length; /* length value */ ! 341: int code; /* code value */ ! 342: int dist; /* distance index */ ! 343: ! 344: file_type = attr; ! 345: file_method = Method; ! 346: compressed_len = input_len = 0L; ! 347: ! 348: #ifdef DYN_ALLOC ! 349: d_buf = (ush far*) fcalloc(DIST_BUFSIZE, sizeof(ush)); ! 350: l_buf = (uch far*) fcalloc(LIT_BUFSIZE/2, 2); ! 351: /* Avoid using the value 64K on 16 bit machines */ ! 352: if (l_buf == NULL || d_buf == NULL) error("ct_init: out of memory"); ! 353: #endif ! 354: ! 355: if (static_dtree[0].Len != 0) return; /* ct_init already called */ ! 356: ! 357: /* Initialize the mapping length (0..255) -> length code (0..28) */ ! 358: length = 0; ! 359: for (code = 0; code < LENGTH_CODES-1; code++) { ! 360: base_length[code] = length; ! 361: for (n = 0; n < (1<<extra_lbits[code]); n++) { ! 362: length_code[length++] = (uch)code; ! 363: } ! 364: } ! 365: Assert (length == 256, "ct_init: length != 256"); ! 366: /* Note that the length 255 (match length 258) can be represented ! 367: * in two different ways: code 284 + 5 bits or code 285, so we ! 368: * overwrite length_code[255] to use the best encoding: ! 369: */ ! 370: length_code[length-1] = (uch)code; ! 371: ! 372: /* Initialize the mapping dist (0..32K) -> dist code (0..29) */ ! 373: dist = 0; ! 374: for (code = 0 ; code < 16; code++) { ! 375: base_dist[code] = dist; ! 376: for (n = 0; n < (1<<extra_dbits[code]); n++) { ! 377: dist_code[dist++] = (uch)code; ! 378: } ! 379: } ! 380: Assert (dist == 256, "ct_init: dist != 256"); ! 381: dist >>= 7; /* from now on, all distances are divided by 128 */ ! 382: for ( ; code < D_CODES; code++) { ! 383: base_dist[code] = dist << 7; ! 384: for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { ! 385: dist_code[256 + dist++] = (uch)code; ! 386: } ! 387: } ! 388: Assert (dist == 256, "ct_init: 256+dist != 512"); ! 389: ! 390: /* Construct the codes of the static literal tree */ ! 391: for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; ! 392: n = 0; ! 393: while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; ! 394: while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; ! 395: while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; ! 396: while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; ! 397: /* Codes 286 and 287 do not exist, but we must include them in the ! 398: * tree construction to get a canonical Huffman tree (longest code ! 399: * all ones) ! 400: */ ! 401: gen_codes(static_ltree, L_CODES+1); ! 402: ! 403: /* The static distance tree is trivial: */ ! 404: for (n = 0; n < D_CODES; n++) { ! 405: static_dtree[n].Len = 5; ! 406: static_dtree[n].Code = bi_reverse(n, 5); ! 407: } ! 408: ! 409: /* Initialize the first block of the first file: */ ! 410: init_block(); ! 411: } ! 412: ! 413: void ct_free() ! 414: { ! 415: #ifdef DYN_ALLOC ! 416: fcfree(d_buf); ! 417: fcfree(l_buf); ! 418: d_buf = NULL; ! 419: l_buf = NULL; ! 420: #endif ! 421: } ! 422: ! 423: /* =========================================================================== ! 424: * Initialize a new block. ! 425: */ ! 426: local void init_block() ! 427: { ! 428: int n; /* iterates over tree elements */ ! 429: ! 430: /* Initialize the trees. */ ! 431: for (n = 0; n < L_CODES; n++) dyn_ltree[n].Freq = 0; ! 432: for (n = 0; n < D_CODES; n++) dyn_dtree[n].Freq = 0; ! 433: for (n = 0; n < BL_CODES; n++) bl_tree[n].Freq = 0; ! 434: ! 435: dyn_ltree[END_BLOCK].Freq = 1; ! 436: opt_len = static_len = 0L; ! 437: last_lit = last_dist = last_flags = 0; ! 438: flags = 0; flag_bit = 1; ! 439: } ! 440: ! 441: #define SMALLEST 1 ! 442: /* Index within the heap array of least frequent node in the Huffman tree */ ! 443: ! 444: ! 445: /* =========================================================================== ! 446: * Remove the smallest element from the heap and recreate the heap with ! 447: * one less element. Updates heap and heap_len. ! 448: */ ! 449: #define pqremove(tree, top) \ ! 450: {\ ! 451: top = heap[SMALLEST]; \ ! 452: heap[SMALLEST] = heap[heap_len--]; \ ! 453: pqdownheap(tree, SMALLEST); \ ! 454: } ! 455: ! 456: /* =========================================================================== ! 457: * Compares to subtrees, using the tree depth as tie breaker when ! 458: * the subtrees have equal frequency. This minimizes the worst case length. ! 459: */ ! 460: #define smaller(tree, n, m) \ ! 461: (tree[n].Freq < tree[m].Freq || \ ! 462: (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) ! 463: ! 464: /* =========================================================================== ! 465: * Restore the heap property by moving down the tree starting at node k, ! 466: * exchanging a node with the smallest of its two sons if necessary, stopping ! 467: * when the heap property is re-established (each father smaller than its ! 468: * two sons). ! 469: */ ! 470: local void pqdownheap(tree, k) ! 471: ct_data near *tree; /* the tree to restore */ ! 472: int k; /* node to move down */ ! 473: { ! 474: int v = heap[k]; ! 475: int j = k << 1; /* left son of k */ ! 476: while (j <= heap_len) { ! 477: /* Set j to the smallest of the two sons: */ ! 478: if (j < heap_len && smaller(tree, heap[j+1], heap[j])) j++; ! 479: ! 480: /* Exit if v is smaller than both sons */ ! 481: if (smaller(tree, v, heap[j])) break; ! 482: ! 483: /* Exchange v with the smallest son */ ! 484: heap[k] = heap[j], k = j; ! 485: ! 486: /* And continue down the tree, setting j to the left son of k */ ! 487: j <<= 1; ! 488: } ! 489: heap[k] = v; ! 490: } ! 491: ! 492: /* =========================================================================== ! 493: * Compute the optimal bit lengths for a tree and update the total bit length ! 494: * for the current block. ! 495: * IN assertion: the fields freq and dad are set, heap[heap_max] and ! 496: * above are the tree nodes sorted by increasing frequency. ! 497: * OUT assertions: the field len is set to the optimal bit length, the ! 498: * array bl_count contains the frequencies for each bit length. ! 499: * The length opt_len is updated; static_len is also updated if stree is ! 500: * not null. ! 501: */ ! 502: local void gen_bitlen(desc) ! 503: tree_desc near *desc; /* the tree descriptor */ ! 504: { ! 505: ct_data near *tree = desc->dyn_tree; ! 506: int near *extra = desc->extra_bits; ! 507: int base = desc->extra_base; ! 508: int max_code = desc->max_code; ! 509: int max_length = desc->max_length; ! 510: ct_data near *stree = desc->static_tree; ! 511: int h; /* heap index */ ! 512: int n, m; /* iterate over the tree elements */ ! 513: int bits; /* bit length */ ! 514: int xbits; /* extra bits */ ! 515: ush f; /* frequency */ ! 516: int overflow = 0; /* number of elements with bit length too large */ ! 517: ! 518: for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; ! 519: ! 520: /* In a first pass, compute the optimal bit lengths (which may ! 521: * overflow in the case of the bit length tree). ! 522: */ ! 523: tree[heap[heap_max]].Len = 0; /* root of the heap */ ! 524: ! 525: for (h = heap_max+1; h < HEAP_SIZE; h++) { ! 526: n = heap[h]; ! 527: bits = tree[tree[n].Dad].Len + 1; ! 528: if (bits > max_length) bits = max_length, overflow++; ! 529: tree[n].Len = bits; ! 530: /* We overwrite tree[n].Dad which is no longer needed */ ! 531: ! 532: if (n > max_code) continue; /* not a leaf node */ ! 533: ! 534: bl_count[bits]++; ! 535: xbits = 0; ! 536: if (n >= base) xbits = extra[n-base]; ! 537: f = tree[n].Freq; ! 538: opt_len += (ulg)f * (bits + xbits); ! 539: if (stree) static_len += (ulg)f * (stree[n].Len + xbits); ! 540: } ! 541: if (overflow == 0) return; ! 542: ! 543: Trace((stderr,"\nbit length overflow\n")); ! 544: /* This happens for example on obj2 and pic of the Calgary corpus */ ! 545: ! 546: /* Find the first bit length which could increase: */ ! 547: do { ! 548: bits = max_length-1; ! 549: while (bl_count[bits] == 0) bits--; ! 550: bl_count[bits]--; /* move one leaf down the tree */ ! 551: bl_count[bits+1] += 2; /* move one overflow item as its brother */ ! 552: bl_count[max_length]--; ! 553: /* The brother of the overflow item also moves one step up, ! 554: * but this does not affect bl_count[max_length] ! 555: */ ! 556: overflow -= 2; ! 557: } while (overflow > 0); ! 558: ! 559: /* Now recompute all bit lengths, scanning in increasing frequency. ! 560: * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all ! 561: * lengths instead of fixing only the wrong ones. This idea is taken ! 562: * from 'ar' written by Haruhiko Okumura.) ! 563: */ ! 564: for (bits = max_length; bits != 0; bits--) { ! 565: n = bl_count[bits]; ! 566: while (n != 0) { ! 567: m = heap[--h]; ! 568: if (m > max_code) continue; ! 569: if (tree[m].Len != (unsigned) bits) { ! 570: Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); ! 571: opt_len += ((long)bits-(long)tree[m].Len)*(long)tree[m].Freq; ! 572: tree[m].Len = bits; ! 573: } ! 574: n--; ! 575: } ! 576: } ! 577: } ! 578: ! 579: /* =========================================================================== ! 580: * Generate the codes for a given tree and bit counts (which need not be ! 581: * optimal). ! 582: * IN assertion: the array bl_count contains the bit length statistics for ! 583: * the given tree and the field len is set for all tree elements. ! 584: * OUT assertion: the field code is set for all tree elements of non ! 585: * zero code length. ! 586: */ ! 587: local void gen_codes (tree, max_code) ! 588: ct_data near *tree; /* the tree to decorate */ ! 589: int max_code; /* largest code with non zero frequency */ ! 590: { ! 591: ush next_code[MAX_BITS+1]; /* next code value for each bit length */ ! 592: ush code = 0; /* running code value */ ! 593: int bits; /* bit index */ ! 594: int n; /* code index */ ! 595: ! 596: /* The distribution counts are first used to generate the code values ! 597: * without bit reversal. ! 598: */ ! 599: for (bits = 1; bits <= MAX_BITS; bits++) { ! 600: next_code[bits] = code = (code + bl_count[bits-1]) << 1; ! 601: } ! 602: /* Check that the bit counts in bl_count are consistent. The last code ! 603: * must be all ones. ! 604: */ ! 605: Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, ! 606: "inconsistent bit counts"); ! 607: Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); ! 608: ! 609: for (n = 0; n <= max_code; n++) { ! 610: int len = tree[n].Len; ! 611: if (len == 0) continue; ! 612: /* Now reverse the bits */ ! 613: tree[n].Code = bi_reverse(next_code[len]++, len); ! 614: ! 615: Tracec(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", ! 616: n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); ! 617: } ! 618: } ! 619: ! 620: /* =========================================================================== ! 621: * Construct one Huffman tree and assigns the code bit strings and lengths. ! 622: * Update the total bit length for the current block. ! 623: * IN assertion: the field freq is set for all tree elements. ! 624: * OUT assertions: the fields len and code are set to the optimal bit length ! 625: * and corresponding code. The length opt_len is updated; static_len is ! 626: * also updated if stree is not null. The field max_code is set. ! 627: */ ! 628: local void build_tree(desc) ! 629: tree_desc near *desc; /* the tree descriptor */ ! 630: { ! 631: ct_data near *tree = desc->dyn_tree; ! 632: ct_data near *stree = desc->static_tree; ! 633: int elems = desc->elems; ! 634: int n, m; /* iterate over heap elements */ ! 635: int max_code = -1; /* largest code with non zero frequency */ ! 636: int node = elems; /* next internal node of the tree */ ! 637: ! 638: /* Construct the initial heap, with least frequent element in ! 639: * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. ! 640: * heap[0] is not used. ! 641: */ ! 642: heap_len = 0, heap_max = HEAP_SIZE; ! 643: ! 644: for (n = 0; n < elems; n++) { ! 645: if (tree[n].Freq != 0) { ! 646: heap[++heap_len] = max_code = n; ! 647: depth[n] = 0; ! 648: } else { ! 649: tree[n].Len = 0; ! 650: } ! 651: } ! 652: ! 653: /* The pkzip format requires that at least one distance code exists, ! 654: * and that at least one bit should be sent even if there is only one ! 655: * possible code. So to avoid special checks later on we force at least ! 656: * two codes of non zero frequency. ! 657: */ ! 658: while (heap_len < 2) { ! 659: int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0); ! 660: tree[new].Freq = 1; ! 661: depth[new] = 0; ! 662: opt_len--; if (stree) static_len -= stree[new].Len; ! 663: /* new is 0 or 1 so it does not have extra bits */ ! 664: } ! 665: desc->max_code = max_code; ! 666: ! 667: /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, ! 668: * establish sub-heaps of increasing lengths: ! 669: */ ! 670: for (n = heap_len/2; n >= 1; n--) pqdownheap(tree, n); ! 671: ! 672: /* Construct the Huffman tree by repeatedly combining the least two ! 673: * frequent nodes. ! 674: */ ! 675: do { ! 676: pqremove(tree, n); /* n = node of least frequency */ ! 677: m = heap[SMALLEST]; /* m = node of next least frequency */ ! 678: ! 679: heap[--heap_max] = n; /* keep the nodes sorted by frequency */ ! 680: heap[--heap_max] = m; ! 681: ! 682: /* Create a new node father of n and m */ ! 683: tree[node].Freq = tree[n].Freq + tree[m].Freq; ! 684: depth[node] = (uch) (MAX(depth[n], depth[m]) + 1); ! 685: tree[n].Dad = tree[m].Dad = node; ! 686: #ifdef DUMP_BL_TREE ! 687: if (tree == bl_tree) { ! 688: fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", ! 689: node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); ! 690: } ! 691: #endif ! 692: /* and insert the new node in the heap */ ! 693: heap[SMALLEST] = node++; ! 694: pqdownheap(tree, SMALLEST); ! 695: ! 696: } while (heap_len >= 2); ! 697: ! 698: heap[--heap_max] = heap[SMALLEST]; ! 699: ! 700: /* At this point, the fields freq and dad are set. We can now ! 701: * generate the bit lengths. ! 702: */ ! 703: gen_bitlen(desc); ! 704: ! 705: /* The field len is now set, we can generate the bit codes */ ! 706: gen_codes (tree, max_code); ! 707: } ! 708: ! 709: /* =========================================================================== ! 710: * Scan a literal or distance tree to determine the frequencies of the codes ! 711: * in the bit length tree. Updates opt_len to take into account the repeat ! 712: * counts. (The contribution of the bit length codes will be added later ! 713: * during the construction of bl_tree.) ! 714: */ ! 715: local void scan_tree (tree, max_code) ! 716: ct_data near *tree; /* the tree to be scanned */ ! 717: int max_code; /* and its largest code of non zero frequency */ ! 718: { ! 719: int n; /* iterates over all tree elements */ ! 720: int prevlen = -1; /* last emitted length */ ! 721: int curlen; /* length of current code */ ! 722: int nextlen = tree[0].Len; /* length of next code */ ! 723: int count = 0; /* repeat count of the current code */ ! 724: int max_count = 7; /* max repeat count */ ! 725: int min_count = 4; /* min repeat count */ ! 726: ! 727: if (nextlen == 0) max_count = 138, min_count = 3; ! 728: tree[max_code+1].Len = (ush)-1; /* guard */ ! 729: ! 730: for (n = 0; n <= max_code; n++) { ! 731: curlen = nextlen; nextlen = tree[n+1].Len; ! 732: if (++count < max_count && curlen == nextlen) { ! 733: continue; ! 734: } else if (count < min_count) { ! 735: bl_tree[curlen].Freq += count; ! 736: } else if (curlen != 0) { ! 737: if (curlen != prevlen) bl_tree[curlen].Freq++; ! 738: bl_tree[REP_3_6].Freq++; ! 739: } else if (count <= 10) { ! 740: bl_tree[REPZ_3_10].Freq++; ! 741: } else { ! 742: bl_tree[REPZ_11_138].Freq++; ! 743: } ! 744: count = 0; prevlen = curlen; ! 745: if (nextlen == 0) { ! 746: max_count = 138, min_count = 3; ! 747: } else if (curlen == nextlen) { ! 748: max_count = 6, min_count = 3; ! 749: } else { ! 750: max_count = 7, min_count = 4; ! 751: } ! 752: } ! 753: } ! 754: ! 755: /* =========================================================================== ! 756: * Send a literal or distance tree in compressed form, using the codes in ! 757: * bl_tree. ! 758: */ ! 759: local void send_tree (tree, max_code) ! 760: ct_data near *tree; /* the tree to be scanned */ ! 761: int max_code; /* and its largest code of non zero frequency */ ! 762: { ! 763: int n; /* iterates over all tree elements */ ! 764: int prevlen = -1; /* last emitted length */ ! 765: int curlen; /* length of current code */ ! 766: int nextlen = tree[0].Len; /* length of next code */ ! 767: int count = 0; /* repeat count of the current code */ ! 768: int max_count = 7; /* max repeat count */ ! 769: int min_count = 4; /* min repeat count */ ! 770: ! 771: /* tree[max_code+1].Len = -1; */ /* guard already set */ ! 772: if (nextlen == 0) max_count = 138, min_count = 3; ! 773: ! 774: for (n = 0; n <= max_code; n++) { ! 775: curlen = nextlen; nextlen = tree[n+1].Len; ! 776: if (++count < max_count && curlen == nextlen) { ! 777: continue; ! 778: } else if (count < min_count) { ! 779: do { send_code(curlen, bl_tree); } while (--count != 0); ! 780: ! 781: } else if (curlen != 0) { ! 782: if (curlen != prevlen) { ! 783: send_code(curlen, bl_tree); count--; ! 784: } ! 785: Assert(count >= 3 && count <= 6, " 3_6?"); ! 786: send_code(REP_3_6, bl_tree); send_bits(count-3, 2); ! 787: ! 788: } else if (count <= 10) { ! 789: send_code(REPZ_3_10, bl_tree); send_bits(count-3, 3); ! 790: ! 791: } else { ! 792: send_code(REPZ_11_138, bl_tree); send_bits(count-11, 7); ! 793: } ! 794: count = 0; prevlen = curlen; ! 795: if (nextlen == 0) { ! 796: max_count = 138, min_count = 3; ! 797: } else if (curlen == nextlen) { ! 798: max_count = 6, min_count = 3; ! 799: } else { ! 800: max_count = 7, min_count = 4; ! 801: } ! 802: } ! 803: } ! 804: ! 805: /* =========================================================================== ! 806: * Construct the Huffman tree for the bit lengths and return the index in ! 807: * bl_order of the last bit length code to send. ! 808: */ ! 809: local int build_bl_tree() ! 810: { ! 811: int max_blindex; /* index of last bit length code of non zero freq */ ! 812: ! 813: /* Determine the bit length frequencies for literal and distance trees */ ! 814: scan_tree(dyn_ltree, l_desc.max_code); ! 815: scan_tree(dyn_dtree, d_desc.max_code); ! 816: ! 817: /* Build the bit length tree: */ ! 818: build_tree(&bl_desc); ! 819: /* opt_len now includes the length of the tree representations, except ! 820: * the lengths of the bit lengths codes and the 5+5+4 bits for the counts. ! 821: */ ! 822: ! 823: /* Determine the number of bit length codes to send. The pkzip format ! 824: * requires that at least 4 bit length codes be sent. (appnote.txt says ! 825: * 3 but the actual value used is 4.) ! 826: */ ! 827: for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { ! 828: if (bl_tree[bl_order[max_blindex]].Len != 0) break; ! 829: } ! 830: /* Update opt_len to include the bit length tree and counts */ ! 831: opt_len += 3*(max_blindex+1) + 5+5+4; ! 832: Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, 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(lcodes, dcodes, blcodes) ! 843: int lcodes, dcodes, blcodes; /* number of codes for each tree */ ! 844: { ! 845: int rank; /* index in bl_order */ ! 846: ! 847: Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); ! 848: Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, ! 849: "too many codes"); ! 850: Tracev((stderr, "\nbl counts: ")); ! 851: send_bits(lcodes-257, 5); /* not -255 as stated in appnote.txt */ ! 852: send_bits(dcodes-1, 5); ! 853: send_bits(blcodes-4, 4); /* not -3 as stated in appnote.txt */ ! 854: for (rank = 0; rank < blcodes; rank++) { ! 855: Tracev((stderr, "\nbl code %2d ", bl_order[rank])); ! 856: send_bits(bl_tree[bl_order[rank]].Len, 3); ! 857: } ! 858: Tracev((stderr, "\nbl tree: sent %ld", bits_sent)); ! 859: ! 860: send_tree(dyn_ltree, lcodes-1); /* send the literal tree */ ! 861: Tracev((stderr, "\nlit tree: sent %ld", bits_sent)); ! 862: ! 863: send_tree(dyn_dtree, dcodes-1); /* send the distance tree */ ! 864: Tracev((stderr, "\ndist tree: sent %ld", bits_sent)); ! 865: } ! 866: ! 867: /* =========================================================================== ! 868: * Determine the best encoding for the current block: dynamic trees, static ! 869: * trees or store, and output the encoded block to the zip file. This function ! 870: * returns the total compressed length for the file so far. ! 871: */ ! 872: ulg flush_block(buf, stored_len, eof) ! 873: char *buf; /* input block, or NULL if too old */ ! 874: ulg stored_len; /* length of input block */ ! 875: int eof; /* true if this is the last block for a file */ ! 876: { ! 877: ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ ! 878: int max_blindex; /* index of last bit length code of non zero freq */ ! 879: ! 880: flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */ ! 881: ! 882: /* Check if the file is ascii or binary */ ! 883: if (*file_type == (ush)UNKNOWN) set_file_type(); ! 884: ! 885: /* Construct the literal and distance trees */ ! 886: build_tree(&l_desc); ! 887: Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len)); ! 888: ! 889: build_tree(&d_desc); ! 890: Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, static_len)); ! 891: /* At this point, opt_len and static_len are the total bit lengths of ! 892: * the compressed block data, excluding the tree representations. ! 893: */ ! 894: ! 895: /* Build the bit length tree for the above two trees, and get the index ! 896: * in bl_order of the last bit length code to send. ! 897: */ ! 898: max_blindex = build_bl_tree(); ! 899: ! 900: /* Determine the best encoding. Compute first the block length in bytes */ ! 901: opt_lenb = (opt_len+3+7)>>3; ! 902: static_lenb = (static_len+3+7)>>3; ! 903: input_len += stored_len; /* for debugging only */ ! 904: ! 905: Trace((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ", ! 906: opt_lenb, opt_len, static_lenb, static_len, stored_len, ! 907: last_lit, last_dist)); ! 908: ! 909: if (static_lenb <= opt_lenb) opt_lenb = static_lenb; ! 910: ! 911: #ifdef ZIP /* not ok for PGP */ ! 912: /* If compression failed and this is the first and last block, ! 913: * and if the zip file can be seeked (to rewrite the local header), ! 914: * the whole file is transformed into a stored file: ! 915: */ ! 916: #ifdef FORCE_METHOD ! 917: if (level == 1 && eof && compressed_len == 0L) { /* force stored file */ ! 918: #else ! 919: if (stored_len <= opt_lenb && eof && compressed_len == 0L && seekable()) { ! 920: #endif ! 921: /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ ! 922: if (buf == NULL) error ("block vanished"); ! 923: ! 924: copy_block(buf, (unsigned)stored_len, 0); /* without header */ ! 925: compressed_len = stored_len << 3; ! 926: *file_method = STORE; ! 927: } else ! 928: #endif /* ZIP */ ! 929: ! 930: #ifdef FORCE_METHOD ! 931: if (level == 2 && buf != NULL) { /* force stored block */ ! 932: #else ! 933: if ((stored_len+4 <= opt_lenb) && (buf != (char *)NULL)) { ! 934: /* 4: two words for the lengths */ ! 935: #endif ! 936: /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. ! 937: * Otherwise we can't have processed more than WSIZE input bytes since ! 938: * the last block flush, because compression would have been ! 939: * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to ! 940: * transform a block into a stored block. ! 941: */ ! 942: send_bits((STORED_BLOCK<<1)+eof, 3); /* send block type */ ! 943: compressed_len = (compressed_len + 3 + 7) & ~7L; ! 944: compressed_len += (stored_len + 4) << 3; ! 945: ! 946: copy_block(buf, (unsigned)stored_len, 1); /* with header */ ! 947: ! 948: #ifdef FORCE_METHOD ! 949: } else if (level == 3) { /* force static trees */ ! 950: #else ! 951: } else if (static_lenb == opt_lenb) { ! 952: #endif ! 953: send_bits((STATIC_TREES<<1)+eof, 3); ! 954: compress_block(static_ltree, static_dtree); ! 955: compressed_len += 3 + static_len; ! 956: } else { ! 957: send_bits((DYN_TREES<<1)+eof, 3); ! 958: send_all_trees(l_desc.max_code+1, d_desc.max_code+1, max_blindex+1); ! 959: compress_block(dyn_ltree, dyn_dtree); ! 960: compressed_len += 3 + opt_len; ! 961: } ! 962: Assert (compressed_len == bits_sent, "bad compressed size"); ! 963: init_block(); ! 964: ! 965: if (eof) { ! 966: #ifndef ZIP ! 967: /* Wipe out sensitive data for pgp */ ! 968: # ifdef DYN_ALLOC ! 969: extern uch *window; ! 970: # else ! 971: extern uch window[]; ! 972: # endif ! 973: memset(window, 0, (unsigned)(2*WSIZE-1)); /* -1 needed if WSIZE=32K */ ! 974: #endif /* ZIP */ ! 975: ! 976: #if 0 ! 977: Assert (input_len == isize, "bad input size"); ! 978: #endif ! 979: bi_windup(); ! 980: compressed_len += 7; /* align on byte boundary */ ! 981: } ! 982: Tracev((stderr,"\ncomprlen %lu(%lu) ", compressed_len>>3, ! 983: compressed_len-7*eof)); ! 984: ! 985: return compressed_len >> 3; ! 986: } ! 987: ! 988: /* =========================================================================== ! 989: * Save the match info and tally the frequency counts. Return true if ! 990: * the current block must be flushed. ! 991: */ ! 992: int ct_tally (dist, lc) ! 993: int dist; /* distance of matched string */ ! 994: int lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ ! 995: { ! 996: l_buf[last_lit++] = (uch)lc; ! 997: if (dist == 0) { ! 998: /* lc is the unmatched char */ ! 999: dyn_ltree[lc].Freq++; ! 1000: } else { ! 1001: /* Here, lc is the match length - MIN_MATCH */ ! 1002: dist--; /* dist = match distance - 1 */ ! 1003: Assert((ush)dist < (ush)MAX_DIST && ! 1004: (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && ! 1005: (ush)d_code(dist) < (ush)D_CODES, "ct_tally: bad match"); ! 1006: ! 1007: dyn_ltree[length_code[lc]+LITERALS+1].Freq++; ! 1008: dyn_dtree[d_code(dist)].Freq++; ! 1009: ! 1010: d_buf[last_dist++] = dist; ! 1011: flags |= flag_bit; ! 1012: } ! 1013: flag_bit <<= 1; ! 1014: ! 1015: /* Output the flags if they fill a byte: */ ! 1016: if ((last_lit & 7) == 0) { ! 1017: flag_buf[last_flags++] = flags; ! 1018: flags = 0, flag_bit = 1; ! 1019: } ! 1020: /* Try to guess if it is profitable to stop the current block here */ ! 1021: if (level > 2 && (last_lit & 0xfff) == 0) { ! 1022: /* Compute an upper bound for the compressed length */ ! 1023: ulg out_length = (ulg)last_lit*8L; ! 1024: ulg in_length = (ulg)strstart-block_start; ! 1025: int dcode; ! 1026: for (dcode = 0; dcode < D_CODES; dcode++) { ! 1027: out_length += (ulg)dyn_dtree[dcode].Freq*(5L+extra_dbits[dcode]); ! 1028: } ! 1029: out_length >>= 3; ! 1030: Trace((stderr,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ", ! 1031: last_lit, last_dist, in_length, out_length, ! 1032: 100L - out_length*100L/in_length)); ! 1033: if (last_dist < last_lit/2 && out_length < in_length/2) return 1; ! 1034: } ! 1035: return (last_lit == LIT_BUFSIZE-1 || last_dist == DIST_BUFSIZE); ! 1036: /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K ! 1037: * on 16 bit machines and because stored blocks are restricted to ! 1038: * 64K-1 bytes. ! 1039: */ ! 1040: } ! 1041: ! 1042: /* =========================================================================== ! 1043: * Send the block data compressed using the given Huffman trees ! 1044: */ ! 1045: local void compress_block(ltree, dtree) ! 1046: ct_data near *ltree; /* literal tree */ ! 1047: ct_data near *dtree; /* distance tree */ ! 1048: { ! 1049: unsigned dist; /* distance of matched string */ ! 1050: int lc; /* match length or unmatched char (if dist == 0) */ ! 1051: unsigned lx = 0; /* running index in l_buf */ ! 1052: unsigned dx = 0; /* running index in d_buf */ ! 1053: unsigned fx = 0; /* running index in flag_buf */ ! 1054: uch flag = 0; /* current flags */ ! 1055: unsigned code; /* the code to send */ ! 1056: int extra; /* number of extra bits to send */ ! 1057: ! 1058: if (last_lit != 0) do { ! 1059: if ((lx & 7) == 0) flag = flag_buf[fx++]; ! 1060: lc = l_buf[lx++]; ! 1061: if ((flag & 1) == 0) { ! 1062: send_code(lc, ltree); /* send a literal byte */ ! 1063: Tracecv(isgraph(lc), (stderr," '%c' ", lc)); ! 1064: } else { ! 1065: /* Here, lc is the match length - MIN_MATCH */ ! 1066: code = length_code[lc]; ! 1067: send_code(code+LITERALS+1, ltree); /* send the length code */ ! 1068: extra = extra_lbits[code]; ! 1069: if (extra != 0) { ! 1070: lc -= base_length[code]; ! 1071: send_bits(lc, extra); /* send the extra length bits */ ! 1072: } ! 1073: dist = d_buf[dx++]; ! 1074: /* Here, dist is the match distance - 1 */ ! 1075: code = d_code(dist); ! 1076: Assert (code < D_CODES, "bad d_code"); ! 1077: ! 1078: send_code(code, dtree); /* send the distance code */ ! 1079: extra = extra_dbits[code]; ! 1080: if (extra != 0) { ! 1081: dist -= base_dist[code]; ! 1082: send_bits(dist, extra); /* send the extra distance bits */ ! 1083: } ! 1084: } /* literal or match pair ? */ ! 1085: flag >>= 1; ! 1086: } while (lx < last_lit); ! 1087: ! 1088: send_code(END_BLOCK, ltree); ! 1089: } ! 1090: ! 1091: /* =========================================================================== ! 1092: * Set the file type to ASCII or BINARY, using a crude approximation: ! 1093: * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise. ! 1094: * IN assertion: the fields freq of dyn_ltree are set and the total of all ! 1095: * frequencies does not exceed 64K (to fit in an int on 16 bit machines). ! 1096: */ ! 1097: local void set_file_type() ! 1098: { ! 1099: int n = 0; ! 1100: unsigned ascii_freq = 0; ! 1101: unsigned bin_freq = 0; ! 1102: while (n < 7) bin_freq += dyn_ltree[n++].Freq; ! 1103: while (n < 128) ascii_freq += dyn_ltree[n++].Freq; ! 1104: while (n < LITERALS) bin_freq += dyn_ltree[n++].Freq; ! 1105: *file_type = bin_freq > (ascii_freq >> 2) ? BINARY : ASCII; ! 1106: #ifdef ZIP ! 1107: if (*file_type == BINARY && translate_eol) { ! 1108: warn("-l used on binary file", ""); ! 1109: } ! 1110: #endif ! 1111: }
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