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/*
* Copyright 2003-2012 by Paulo Soares.
*
* This code was originally released in 2001 by SUN (see class
* com.sun.media.imageioimpl.plugins.tiff.TIFFFaxDecompressor.java)
* using the BSD license in a specific wording. In a mail dating from
* January 23, 2008, Brian Burkhalter (@sun.com) gave us permission
* to use the code under the following version of the BSD license:
*
* Copyright (c) 2005 Sun Microsystems, Inc. All  Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistribution of source code must retain the above copyright
*   notice, this  list of conditions and the following disclaimer.
*
* - Redistribution in binary form must reproduce the above copyright
*   notice, this list of conditions and the following disclaimer in
*   the documentation and/or other materials provided with the
*   distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any
* kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
* WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
* EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL
* NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF
* USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR
* ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
* CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
* REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
* INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed or intended for
* use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
package com.itextpdf.io.codec;

import com.itextpdf.io.exceptions.IOException;

/**
 * Class that can decompress TIFF files.
 */
public class TIFFFaxDecompressor {

    /**
     * The logical order of bits within a byte.
     * 
     * 1 = MSB-to-LSB
     * 2 = LSB-to-MSB (flipped)
     * 
*/ protected int fillOrder; protected int compression; private int t4Options; private int t6Options; public int fails; // Variables set by T4Options /** * Uncompressed mode flag: 1 if uncompressed, 0 if not. */ protected int uncompressedMode = 0; /** * EOL padding flag: 1 if fill bits have been added before an EOL such * that the EOL ends on a byte boundary, 0 otherwise. */ protected int fillBits = 0; /** * Coding dimensionality: 1 for 2-dimensional, 0 for 1-dimensional. */ protected int oneD; private byte[] data; private int bitPointer, bytePointer; // Output image buffer private byte[] buffer; private int w, h, bitsPerScanline; private int lineBitNum; // Data structures needed to store changing elements for the previous // and the current scanline private int changingElemSize = 0; private int prevChangingElems[]; private int currChangingElems[]; // Element at which to start search in getNextChangingElement private int lastChangingElement = 0; private final Object lock = new Object(); static int[] table1 = { 0x00, // 0 bits are left in first byte - SHOULD NOT HAPPEN 0x01, // 1 bits are left in first byte 0x03, // 2 bits are left in first byte 0x07, // 3 bits are left in first byte 0x0f, // 4 bits are left in first byte 0x1f, // 5 bits are left in first byte 0x3f, // 6 bits are left in first byte 0x7f, // 7 bits are left in first byte 0xff // 8 bits are left in first byte }; static int[] table2 = { 0x00, // 0 0x80, // 1 0xc0, // 2 0xe0, // 3 0xf0, // 4 0xf8, // 5 0xfc, // 6 0xfe, // 7 0xff // 8 }; // Table to be used when fillOrder = 2, for flipping bytes. static byte[] flipTable = { (byte) 0x00, (byte) 0x80, (byte) 0x40, (byte) 0xc0, (byte) 0x20, (byte) 0xa0, (byte) 0x60, (byte) 0xe0, (byte) 0x10, (byte) 0x90, (byte) 0x50, (byte) 0xd0, (byte) 0x30, (byte) 0xb0, (byte) 0x70, (byte) 0xf0, (byte) 0x08, (byte) 0x88, (byte) 0x48, (byte) 0xc8, (byte) 0x28, (byte) 0xa8, (byte) 0x68, (byte) 0xe8, (byte) 0x18, (byte) 0x98, (byte) 0x58, (byte) 0xd8, (byte) 0x38, (byte) 0xb8, (byte) 0x78, (byte) 0xf8, (byte) 0x04, (byte) 0x84, (byte) 0x44, (byte) 0xc4, (byte) 0x24, (byte) 0xa4, (byte) 0x64, (byte) 0xe4, (byte) 0x14, (byte) 0x94, (byte) 0x54, (byte) 0xd4, (byte) 0x34, (byte) 0xb4, (byte) 0x74, (byte) 0xf4, (byte) 0x0c, (byte) 0x8c, (byte) 0x4c, (byte) 0xcc, (byte) 0x2c, (byte) 0xac, (byte) 0x6c, (byte) 0xec, (byte) 0x1c, (byte) 0x9c, (byte) 0x5c, (byte) 0xdc, (byte) 0x3c, (byte) 0xbc, (byte) 0x7c, (byte) 0xfc, (byte) 0x02, (byte) 0x82, (byte) 0x42, (byte) 0xc2, (byte) 0x22, (byte) 0xa2, (byte) 0x62, (byte) 0xe2, (byte) 0x12, (byte) 0x92, (byte) 0x52, (byte) 0xd2, (byte) 0x32, (byte) 0xb2, (byte) 0x72, (byte) 0xf2, (byte) 0x0a, (byte) 0x8a, (byte) 0x4a, (byte) 0xca, (byte) 0x2a, (byte) 0xaa, (byte) 0x6a, (byte) 0xea, (byte) 0x1a, (byte) 0x9a, (byte) 0x5a, (byte) 0xda, (byte) 0x3a, (byte) 0xba, (byte) 0x7a, (byte) 0xfa, (byte) 0x06, (byte) 0x86, (byte) 0x46, (byte) 0xc6, (byte) 0x26, (byte) 0xa6, (byte) 0x66, (byte) 0xe6, (byte) 0x16, (byte) 0x96, (byte) 0x56, (byte) 0xd6, (byte) 0x36, (byte) 0xb6, (byte) 0x76, (byte) 0xf6, (byte) 0x0e, (byte) 0x8e, (byte) 0x4e, (byte) 0xce, (byte) 0x2e, (byte) 0xae, (byte) 0x6e, (byte) 0xee, (byte) 0x1e, (byte) 0x9e, (byte) 0x5e, (byte) 0xde, (byte) 0x3e, (byte) 0xbe, (byte) 0x7e, (byte) 0xfe, (byte) 0x01, (byte) 0x81, (byte) 0x41, (byte) 0xc1, (byte) 0x21, (byte) 0xa1, (byte) 0x61, (byte) 0xe1, (byte) 0x11, (byte) 0x91, (byte) 0x51, (byte) 0xd1, (byte) 0x31, (byte) 0xb1, (byte) 0x71, (byte) 0xf1, (byte) 0x09, (byte) 0x89, (byte) 0x49, (byte) 0xc9, (byte) 0x29, (byte) 0xa9, (byte) 0x69, (byte) 0xe9, (byte) 0x19, (byte) 0x99, (byte) 0x59, (byte) 0xd9, (byte) 0x39, (byte) 0xb9, (byte) 0x79, (byte) 0xf9, (byte) 0x05, (byte) 0x85, (byte) 0x45, (byte) 0xc5, (byte) 0x25, (byte) 0xa5, (byte) 0x65, (byte) 0xe5, (byte) 0x15, (byte) 0x95, (byte) 0x55, (byte) 0xd5, (byte) 0x35, (byte) 0xb5, (byte) 0x75, (byte) 0xf5, (byte) 0x0d, (byte) 0x8d, (byte) 0x4d, (byte) 0xcd, (byte) 0x2d, (byte) 0xad, (byte) 0x6d, (byte) 0xed, (byte) 0x1d, (byte) 0x9d, (byte) 0x5d, (byte) 0xdd, (byte) 0x3d, (byte) 0xbd, (byte) 0x7d, (byte) 0xfd, (byte) 0x03, (byte) 0x83, (byte) 0x43, (byte) 0xc3, (byte) 0x23, (byte) 0xa3, (byte) 0x63, (byte) 0xe3, (byte) 0x13, (byte) 0x93, (byte) 0x53, (byte) 0xd3, (byte) 0x33, (byte) 0xb3, (byte) 0x73, (byte) 0xf3, (byte) 0x0b, (byte) 0x8b, (byte) 0x4b, (byte) 0xcb, (byte) 0x2b, (byte) 0xab, (byte) 0x6b, (byte) 0xeb, (byte) 0x1b, (byte) 0x9b, (byte) 0x5b, (byte) 0xdb, (byte) 0x3b, (byte) 0xbb, (byte) 0x7b, (byte) 0xfb, (byte) 0x07, (byte) 0x87, (byte) 0x47, (byte) 0xc7, (byte) 0x27, (byte) 0xa7, (byte) 0x67, (byte) 0xe7, (byte) 0x17, (byte) 0x97, (byte) 0x57, (byte) 0xd7, (byte) 0x37, (byte) 0xb7, (byte) 0x77, (byte) 0xf7, (byte) 0x0f, (byte) 0x8f, (byte) 0x4f, (byte) 0xcf, (byte) 0x2f, (byte) 0xaf, (byte) 0x6f, (byte) 0xef, (byte) 0x1f, (byte) 0x9f, (byte) 0x5f, (byte) 0xdf, (byte) 0x3f, (byte) 0xbf, (byte) 0x7f, (byte) 0xff }; // The main 10 bit white runs lookup table static short[] white = { // 0 - 7 6430, 6400, 6400, 6400, 3225, 3225, 3225, 3225, // 8 - 15 944, 944, 944, 944, 976, 976, 976, 976, // 16 - 23 1456, 1456, 1456, 1456, 1488, 1488, 1488, 1488, // 24 - 31 718, 718, 718, 718, 718, 718, 718, 718, // 32 - 39 750, 750, 750, 750, 750, 750, 750, 750, // 40 - 47 1520, 1520, 1520, 1520, 1552, 1552, 1552, 1552, // 48 - 55 428, 428, 428, 428, 428, 428, 428, 428, // 56 - 63 428, 428, 428, 428, 428, 428, 428, 428, // 64 - 71 654, 654, 654, 654, 654, 654, 654, 654, // 72 - 79 1072, 1072, 1072, 1072, 1104, 1104, 1104, 1104, // 80 - 87 1136, 1136, 1136, 1136, 1168, 1168, 1168, 1168, // 88 - 95 1200, 1200, 1200, 1200, 1232, 1232, 1232, 1232, // 96 - 103 622, 622, 622, 622, 622, 622, 622, 622, // 104 - 111 1008, 1008, 1008, 1008, 1040, 1040, 1040, 1040, // 112 - 119 44, 44, 44, 44, 44, 44, 44, 44, // 120 - 127 44, 44, 44, 44, 44, 44, 44, 44, // 128 - 135 396, 396, 396, 396, 396, 396, 396, 396, // 136 - 143 396, 396, 396, 396, 396, 396, 396, 396, // 144 - 151 1712, 1712, 1712, 1712, 1744, 1744, 1744, 1744, // 152 - 159 846, 846, 846, 846, 846, 846, 846, 846, // 160 - 167 1264, 1264, 1264, 1264, 1296, 1296, 1296, 1296, // 168 - 175 1328, 1328, 1328, 1328, 1360, 1360, 1360, 1360, // 176 - 183 1392, 1392, 1392, 1392, 1424, 1424, 1424, 1424, // 184 - 191 686, 686, 686, 686, 686, 686, 686, 686, // 192 - 199 910, 910, 910, 910, 910, 910, 910, 910, // 200 - 207 1968, 1968, 1968, 1968, 2000, 2000, 2000, 2000, // 208 - 215 2032, 2032, 2032, 2032, 16, 16, 16, 16, // 216 - 223 10257, 10257, 10257, 10257, 12305, 12305, 12305, 12305, // 224 - 231 330, 330, 330, 330, 330, 330, 330, 330, // 232 - 239 330, 330, 330, 330, 330, 330, 330, 330, // 240 - 247 330, 330, 330, 330, 330, 330, 330, 330, // 248 - 255 330, 330, 330, 330, 330, 330, 330, 330, // 256 - 263 362, 362, 362, 362, 362, 362, 362, 362, // 264 - 271 362, 362, 362, 362, 362, 362, 362, 362, // 272 - 279 362, 362, 362, 362, 362, 362, 362, 362, // 280 - 287 362, 362, 362, 362, 362, 362, 362, 362, // 288 - 295 878, 878, 878, 878, 878, 878, 878, 878, // 296 - 303 1904, 1904, 1904, 1904, 1936, 1936, 1936, 1936, // 304 - 311 -18413, -18413, -16365, -16365, -14317, -14317, -10221, -10221, // 312 - 319 590, 590, 590, 590, 590, 590, 590, 590, // 320 - 327 782, 782, 782, 782, 782, 782, 782, 782, // 328 - 335 1584, 1584, 1584, 1584, 1616, 1616, 1616, 1616, // 336 - 343 1648, 1648, 1648, 1648, 1680, 1680, 1680, 1680, // 344 - 351 814, 814, 814, 814, 814, 814, 814, 814, // 352 - 359 1776, 1776, 1776, 1776, 1808, 1808, 1808, 1808, // 360 - 367 1840, 1840, 1840, 1840, 1872, 1872, 1872, 1872, // 368 - 375 6157, 6157, 6157, 6157, 6157, 6157, 6157, 6157, // 376 - 383 6157, 6157, 6157, 6157, 6157, 6157, 6157, 6157, // 384 - 391 -12275, -12275, -12275, -12275, -12275, -12275, -12275, -12275, // 392 - 399 -12275, -12275, -12275, -12275, -12275, -12275, -12275, -12275, // 400 - 407 14353, 14353, 14353, 14353, 16401, 16401, 16401, 16401, // 408 - 415 22547, 22547, 24595, 24595, 20497, 20497, 20497, 20497, // 416 - 423 18449, 18449, 18449, 18449, 26643, 26643, 28691, 28691, // 424 - 431 30739, 30739, -32749, -32749, -30701, -30701, -28653, -28653, // 432 - 439 -26605, -26605, -24557, -24557, -22509, -22509, -20461, -20461, // 440 - 447 8207, 8207, 8207, 8207, 8207, 8207, 8207, 8207, // 448 - 455 72, 72, 72, 72, 72, 72, 72, 72, // 456 - 463 72, 72, 72, 72, 72, 72, 72, 72, // 464 - 471 72, 72, 72, 72, 72, 72, 72, 72, // 472 - 479 72, 72, 72, 72, 72, 72, 72, 72, // 480 - 487 72, 72, 72, 72, 72, 72, 72, 72, // 488 - 495 72, 72, 72, 72, 72, 72, 72, 72, // 496 - 503 72, 72, 72, 72, 72, 72, 72, 72, // 504 - 511 72, 72, 72, 72, 72, 72, 72, 72, // 512 - 519 104, 104, 104, 104, 104, 104, 104, 104, // 520 - 527 104, 104, 104, 104, 104, 104, 104, 104, // 528 - 535 104, 104, 104, 104, 104, 104, 104, 104, // 536 - 543 104, 104, 104, 104, 104, 104, 104, 104, // 544 - 551 104, 104, 104, 104, 104, 104, 104, 104, // 552 - 559 104, 104, 104, 104, 104, 104, 104, 104, // 560 - 567 104, 104, 104, 104, 104, 104, 104, 104, // 568 - 575 104, 104, 104, 104, 104, 104, 104, 104, // 576 - 583 4107, 4107, 4107, 4107, 4107, 4107, 4107, 4107, // 584 - 591 4107, 4107, 4107, 4107, 4107, 4107, 4107, 4107, // 592 - 599 4107, 4107, 4107, 4107, 4107, 4107, 4107, 4107, // 600 - 607 4107, 4107, 4107, 4107, 4107, 4107, 4107, 4107, // 608 - 615 266, 266, 266, 266, 266, 266, 266, 266, // 616 - 623 266, 266, 266, 266, 266, 266, 266, 266, // 624 - 631 266, 266, 266, 266, 266, 266, 266, 266, // 632 - 639 266, 266, 266, 266, 266, 266, 266, 266, // 640 - 647 298, 298, 298, 298, 298, 298, 298, 298, // 648 - 655 298, 298, 298, 298, 298, 298, 298, 298, // 656 - 663 298, 298, 298, 298, 298, 298, 298, 298, // 664 - 671 298, 298, 298, 298, 298, 298, 298, 298, // 672 - 679 524, 524, 524, 524, 524, 524, 524, 524, // 680 - 687 524, 524, 524, 524, 524, 524, 524, 524, // 688 - 695 556, 556, 556, 556, 556, 556, 556, 556, // 696 - 703 556, 556, 556, 556, 556, 556, 556, 556, // 704 - 711 136, 136, 136, 136, 136, 136, 136, 136, // 712 - 719 136, 136, 136, 136, 136, 136, 136, 136, // 720 - 727 136, 136, 136, 136, 136, 136, 136, 136, // 728 - 735 136, 136, 136, 136, 136, 136, 136, 136, // 736 - 743 136, 136, 136, 136, 136, 136, 136, 136, // 744 - 751 136, 136, 136, 136, 136, 136, 136, 136, // 752 - 759 136, 136, 136, 136, 136, 136, 136, 136, // 760 - 767 136, 136, 136, 136, 136, 136, 136, 136, // 768 - 775 168, 168, 168, 168, 168, 168, 168, 168, // 776 - 783 168, 168, 168, 168, 168, 168, 168, 168, // 784 - 791 168, 168, 168, 168, 168, 168, 168, 168, // 792 - 799 168, 168, 168, 168, 168, 168, 168, 168, // 800 - 807 168, 168, 168, 168, 168, 168, 168, 168, // 808 - 815 168, 168, 168, 168, 168, 168, 168, 168, // 816 - 823 168, 168, 168, 168, 168, 168, 168, 168, // 824 - 831 168, 168, 168, 168, 168, 168, 168, 168, // 832 - 839 460, 460, 460, 460, 460, 460, 460, 460, // 840 - 847 460, 460, 460, 460, 460, 460, 460, 460, // 848 - 855 492, 492, 492, 492, 492, 492, 492, 492, // 856 - 863 492, 492, 492, 492, 492, 492, 492, 492, // 864 - 871 2059, 2059, 2059, 2059, 2059, 2059, 2059, 2059, // 872 - 879 2059, 2059, 2059, 2059, 2059, 2059, 2059, 2059, // 880 - 887 2059, 2059, 2059, 2059, 2059, 2059, 2059, 2059, // 888 - 895 2059, 2059, 2059, 2059, 2059, 2059, 2059, 2059, // 896 - 903 200, 200, 200, 200, 200, 200, 200, 200, // 904 - 911 200, 200, 200, 200, 200, 200, 200, 200, // 912 - 919 200, 200, 200, 200, 200, 200, 200, 200, // 920 - 927 200, 200, 200, 200, 200, 200, 200, 200, // 928 - 935 200, 200, 200, 200, 200, 200, 200, 200, // 936 - 943 200, 200, 200, 200, 200, 200, 200, 200, // 944 - 951 200, 200, 200, 200, 200, 200, 200, 200, // 952 - 959 200, 200, 200, 200, 200, 200, 200, 200, // 960 - 967 232, 232, 232, 232, 232, 232, 232, 232, // 968 - 975 232, 232, 232, 232, 232, 232, 232, 232, // 976 - 983 232, 232, 232, 232, 232, 232, 232, 232, // 984 - 991 232, 232, 232, 232, 232, 232, 232, 232, // 992 - 999 232, 232, 232, 232, 232, 232, 232, 232, // 1000 - 1007 232, 232, 232, 232, 232, 232, 232, 232, // 1008 - 1015 232, 232, 232, 232, 232, 232, 232, 232, // 1016 - 1023 232, 232, 232, 232, 232, 232, 232, 232,}; // Additional make up codes for both White and Black runs // static short[] additionalMakeup = { // 28679, 28679, 31752, (short)32777, // (short)33801, (short)34825, (short)35849, (short)36873, // (short)29703, (short)29703, (short)30727, (short)30727, // (short)37897, (short)38921, (short)39945, (short)40969 // }; //replace with constants without overload public static short[] additionalMakeup = { 28679, 28679, 31752, -32759, -31735, -30711, -29687, -28663, 29703, 29703, 30727, 30727, -27639, -26615, -25591, -24567 }; // Initial black run look up table, uses the first 4 bits of a code static short[] initBlack = { // 0 - 7 3226, 6412, 200, 168, 38, 38, 134, 134, // 8 - 15 100, 100, 100, 100, 68, 68, 68, 68 }; // static short[] twoBitBlack = {292, 260, 226, 226}; // 0 - 3 // Main black run table, using the last 9 bits of possible 13 bit code static short[] black = { // 0 - 7 62, 62, 30, 30, 0, 0, 0, 0, // 8 - 15 0, 0, 0, 0, 0, 0, 0, 0, // 16 - 23 0, 0, 0, 0, 0, 0, 0, 0, // 24 - 31 0, 0, 0, 0, 0, 0, 0, 0, // 32 - 39 3225, 3225, 3225, 3225, 3225, 3225, 3225, 3225, // 40 - 47 3225, 3225, 3225, 3225, 3225, 3225, 3225, 3225, // 48 - 55 3225, 3225, 3225, 3225, 3225, 3225, 3225, 3225, // 56 - 63 3225, 3225, 3225, 3225, 3225, 3225, 3225, 3225, // 64 - 71 588, 588, 588, 588, 588, 588, 588, 588, // 72 - 79 1680, 1680, 20499, 22547, 24595, 26643, 1776, 1776, // 80 - 87 1808, 1808, -24557, -22509, -20461, -18413, 1904, 1904, // 88 - 95 1936, 1936, -16365, -14317, 782, 782, 782, 782, // 96 - 103 814, 814, 814, 814, -12269, -10221, 10257, 10257, // 104 - 111 12305, 12305, 14353, 14353, 16403, 18451, 1712, 1712, // 112 - 119 1744, 1744, 28691, 30739, -32749, -30701, -28653, -26605, // 120 - 127 2061, 2061, 2061, 2061, 2061, 2061, 2061, 2061, // 128 - 135 424, 424, 424, 424, 424, 424, 424, 424, // 136 - 143 424, 424, 424, 424, 424, 424, 424, 424, // 144 - 151 424, 424, 424, 424, 424, 424, 424, 424, // 152 - 159 424, 424, 424, 424, 424, 424, 424, 424, // 160 - 167 750, 750, 750, 750, 1616, 1616, 1648, 1648, // 168 - 175 1424, 1424, 1456, 1456, 1488, 1488, 1520, 1520, // 176 - 183 1840, 1840, 1872, 1872, 1968, 1968, 8209, 8209, // 184 - 191 524, 524, 524, 524, 524, 524, 524, 524, // 192 - 199 556, 556, 556, 556, 556, 556, 556, 556, // 200 - 207 1552, 1552, 1584, 1584, 2000, 2000, 2032, 2032, // 208 - 215 976, 976, 1008, 1008, 1040, 1040, 1072, 1072, // 216 - 223 1296, 1296, 1328, 1328, 718, 718, 718, 718, // 224 - 231 456, 456, 456, 456, 456, 456, 456, 456, // 232 - 239 456, 456, 456, 456, 456, 456, 456, 456, // 240 - 247 456, 456, 456, 456, 456, 456, 456, 456, // 248 - 255 456, 456, 456, 456, 456, 456, 456, 456, // 256 - 263 326, 326, 326, 326, 326, 326, 326, 326, // 264 - 271 326, 326, 326, 326, 326, 326, 326, 326, // 272 - 279 326, 326, 326, 326, 326, 326, 326, 326, // 280 - 287 326, 326, 326, 326, 326, 326, 326, 326, // 288 - 295 326, 326, 326, 326, 326, 326, 326, 326, // 296 - 303 326, 326, 326, 326, 326, 326, 326, 326, // 304 - 311 326, 326, 326, 326, 326, 326, 326, 326, // 312 - 319 326, 326, 326, 326, 326, 326, 326, 326, // 320 - 327 358, 358, 358, 358, 358, 358, 358, 358, // 328 - 335 358, 358, 358, 358, 358, 358, 358, 358, // 336 - 343 358, 358, 358, 358, 358, 358, 358, 358, // 344 - 351 358, 358, 358, 358, 358, 358, 358, 358, // 352 - 359 358, 358, 358, 358, 358, 358, 358, 358, // 360 - 367 358, 358, 358, 358, 358, 358, 358, 358, // 368 - 375 358, 358, 358, 358, 358, 358, 358, 358, // 376 - 383 358, 358, 358, 358, 358, 358, 358, 358, // 384 - 391 490, 490, 490, 490, 490, 490, 490, 490, // 392 - 399 490, 490, 490, 490, 490, 490, 490, 490, // 400 - 407 4113, 4113, 6161, 6161, 848, 848, 880, 880, // 408 - 415 912, 912, 944, 944, 622, 622, 622, 622, // 416 - 423 654, 654, 654, 654, 1104, 1104, 1136, 1136, // 424 - 431 1168, 1168, 1200, 1200, 1232, 1232, 1264, 1264, // 432 - 439 686, 686, 686, 686, 1360, 1360, 1392, 1392, // 440 - 447 12, 12, 12, 12, 12, 12, 12, 12, // 448 - 455 390, 390, 390, 390, 390, 390, 390, 390, // 456 - 463 390, 390, 390, 390, 390, 390, 390, 390, // 464 - 471 390, 390, 390, 390, 390, 390, 390, 390, // 472 - 479 390, 390, 390, 390, 390, 390, 390, 390, // 480 - 487 390, 390, 390, 390, 390, 390, 390, 390, // 488 - 495 390, 390, 390, 390, 390, 390, 390, 390, // 496 - 503 390, 390, 390, 390, 390, 390, 390, 390, // 504 - 511 390, 390, 390, 390, 390, 390, 390, 390,}; static byte[] twoDCodes = { // 0 - 7 80, 88, 23, 71, 30, 30, 62, 62, // 8 - 15 4, 4, 4, 4, 4, 4, 4, 4, // 16 - 23 11, 11, 11, 11, 11, 11, 11, 11, // 24 - 31 11, 11, 11, 11, 11, 11, 11, 11, // 32 - 39 35, 35, 35, 35, 35, 35, 35, 35, // 40 - 47 35, 35, 35, 35, 35, 35, 35, 35, // 48 - 55 51, 51, 51, 51, 51, 51, 51, 51, // 56 - 63 51, 51, 51, 51, 51, 51, 51, 51, // 64 - 71 41, 41, 41, 41, 41, 41, 41, 41, // 72 - 79 41, 41, 41, 41, 41, 41, 41, 41, // 80 - 87 41, 41, 41, 41, 41, 41, 41, 41, // 88 - 95 41, 41, 41, 41, 41, 41, 41, 41, // 96 - 103 41, 41, 41, 41, 41, 41, 41, 41, // 104 - 111 41, 41, 41, 41, 41, 41, 41, 41, // 112 - 119 41, 41, 41, 41, 41, 41, 41, 41, // 120 - 127 41, 41, 41, 41, 41, 41, 41, 41,}; public TIFFFaxDecompressor() { } /** * Invokes the superclass method and then sets instance variables on * the basis of the metadata set on this decompressor. * @param fillOrder The fill order * @param compression The compression algorithm * @param t4Options The T4 options * @param t6Options The T6 options */ public void SetOptions(int fillOrder, int compression, int t4Options, int t6Options) { this.fillOrder = fillOrder; this.compression = compression; this.t4Options = t4Options; this.t6Options = t6Options; this.oneD = t4Options & 0x01; this.uncompressedMode = (t4Options & 0x02) >> 1; this.fillBits = (t4Options & 0x04) >> 2; } public void decodeRaw(byte[] buffer, byte[] compData, int w, int h) { this.buffer = buffer; this.data = compData; this.w = w; this.h = h; this.bitsPerScanline = w; this.lineBitNum = 0; this.bitPointer = 0; this.bytePointer = 0; this.prevChangingElems = new int[w + 1]; this.currChangingElems = new int[w + 1]; fails = 0; try { if (compression == TIFFConstants.COMPRESSION_CCITTRLE) { decodeRLE(); } else if (compression == TIFFConstants.COMPRESSION_CCITTFAX3) { decodeT4(); } else if (compression == TIFFConstants.COMPRESSION_CCITTFAX4) { this.uncompressedMode = (t6Options & 0x02) >> 1; decodeT6(); } else { throw new IOException(IOException.UnknownCompressionType1).setMessageParams(compression); } } catch (ArrayIndexOutOfBoundsException e) { //ignore } } public void decodeRLE() { for (int i = 0; i < h; i++) { // Decode the line. decodeNextScanline(); // Advance to the next byte boundary if not already there. if (bitPointer != 0) { bytePointer++; bitPointer = 0; } // Update the total number of bits. lineBitNum += bitsPerScanline; } } public void decodeNextScanline() { int bits = 0, code = 0, isT = 0; int current, entry, twoBits; boolean isWhite = true; int bitOffset = 0; // Initialize starting of the changing elements array changingElemSize = 0; // While scanline not complete while (bitOffset < w) { // Mark start of white run. int runOffset = bitOffset; while (isWhite && bitOffset < w) { // White run current = nextNBits(10); entry = white[current]; // Get the 3 fields from the entry isT = entry & 0x0001; bits = (entry >>> 1) & 0x0f; if (bits == 12) { // Additional Make up code // Get the next 2 bits twoBits = nextLesserThan8Bits(2); // Consolidate the 2 new bits and last 2 bits into 4 bits current = ((current << 2) & 0x000c) | twoBits; entry = additionalMakeup[current]; bits = (entry >>> 1) & 0x07; // 3 bits 0000 0111 code = (entry >>> 4) & 0x0fff; // 12 bits bitOffset += code; // Skip white run updatePointer(4 - bits); } else if (bits == 0) { // ERROR ++fails; // XXX return? } else if (bits == 15) { // EOL // // Instead of throwing an exception, assume that the // EOL was premature; emit a warning and return. // ++fails; return; } else { // 11 bits - 0000 0111 1111 1111 = 0x07ff code = (entry >>> 5) & 0x07ff; bitOffset += code; updatePointer(10 - bits); if (isT == 0) { isWhite = false; currChangingElems[changingElemSize++] = bitOffset; } } } // Check whether this run completed one width if (bitOffset == w) { // If the white run has not been terminated then ensure that // the next code word is a terminating code for a white run // of length zero. int runLength = bitOffset - runOffset; if (isWhite && runLength != 0 && runLength % 64 == 0 && nextNBits(8) != 0x35) { ++fails; updatePointer(8); } break; } // Mark start of black run. runOffset = bitOffset; while (!isWhite && bitOffset < w) { // Black run current = nextLesserThan8Bits(4); entry = initBlack[current]; // Get the 3 fields from the entry isT = entry & 0x0001; bits = (entry >>> 1) & 0x000f; code = (entry >>> 5) & 0x07ff; if (code == 100) { current = nextNBits(9); entry = black[current]; // Get the 3 fields from the entry isT = entry & 0x0001; bits = (entry >>> 1) & 0x000f; code = (entry >>> 5) & 0x07ff; if (bits == 12) { // Additional makeup codes updatePointer(5); current = nextLesserThan8Bits(4); entry = additionalMakeup[current]; bits = (entry >>> 1) & 0x07; // 3 bits 0000 0111 code = (entry >>> 4) & 0x0fff; // 12 bits setToBlack(bitOffset, code); bitOffset += code; updatePointer(4 - bits); } else if (bits == 15) { // // Instead of throwing an exception, assume that the // EOL was premature; emit a warning and return. // ++fails; return; } else { setToBlack(bitOffset, code); bitOffset += code; updatePointer(9 - bits); if (isT == 0) { isWhite = true; currChangingElems[changingElemSize++] = bitOffset; } } } else if (code == 200) { // Is a Terminating code current = nextLesserThan8Bits(2); entry = twoBitBlack[current]; code = (entry >>> 5) & 0x07ff; bits = (entry >>> 1) & 0x0f; setToBlack(bitOffset, code); bitOffset += code; updatePointer(2 - bits); isWhite = true; currChangingElems[changingElemSize++] = bitOffset; } else { // Is a Terminating code setToBlack(bitOffset, code); bitOffset += code; updatePointer(4 - bits); isWhite = true; currChangingElems[changingElemSize++] = bitOffset; } } // Check whether this run completed one width if (bitOffset == w) { // If the black run has not been terminated then ensure that // the next code word is a terminating code for a black run // of length zero. int runLength = bitOffset - runOffset; if (!isWhite && runLength != 0 && runLength % 64 == 0 && nextNBits(10) != 0x37) { ++fails; updatePointer(10); } break; } } currChangingElems[changingElemSize++] = bitOffset; } public void decodeT4() { int height = h; int a0, a1, b1, b2; int[] b = new int[2]; int entry, code, bits, color; boolean isWhite; int currIndex = 0; int temp[]; if (data.length < 2) { throw new RuntimeException("Insufficient data to read initial EOL."); } // The data should start with an EOL code int next12 = nextNBits(12); if (next12 != 1) { ++fails; } updatePointer(12); // Find the first one-dimensionally encoded line. int modeFlag = 0; int lines = -1; // indicates imaginary line before first actual line. while (modeFlag != 1) { try { modeFlag = findNextLine(); lines++; // Normally 'lines' will be 0 on exiting loop. } catch (Exception eofe) { throw new RuntimeException("No reference line present."); } } int bitOffset; // Then the 1D encoded scanline data will occur, changing elements // array gets set. decodeNextScanline(); lines++; lineBitNum += bitsPerScanline; while (lines < height) { // Every line must begin with an EOL followed by a bit which // indicates whether the following scanline is 1D or 2D encoded. try { modeFlag = findNextLine(); } catch (Exception eofe) { ++fails; break; } if (modeFlag == 0) { // 2D encoded scanline follows // Initialize previous scanlines changing elements, and // initialize current scanline's changing elements array temp = prevChangingElems; prevChangingElems = currChangingElems; currChangingElems = temp; currIndex = 0; // a0 has to be set just before the start of this scanline. a0 = -1; isWhite = true; bitOffset = 0; lastChangingElement = 0; while (bitOffset < w) { // Get the next changing element getNextChangingElement(a0, isWhite, b); b1 = b[0]; b2 = b[1]; // Get the next seven bits entry = nextLesserThan8Bits(7); // Run these through the 2DCodes table entry = twoDCodes[entry] & 0xff; // Get the code and the number of bits used up code = (entry & 0x78) >>> 3; bits = entry & 0x07; if (code == 0) { if (!isWhite) { setToBlack(bitOffset, b2 - bitOffset); } bitOffset = a0 = b2; // Set pointer to consume the correct number of bits. updatePointer(7 - bits); } else if (code == 1) { // Horizontal updatePointer(7 - bits); // identify the next 2 codes. int number; if (isWhite) { number = decodeWhiteCodeWord(); bitOffset += number; currChangingElems[currIndex++] = bitOffset; number = decodeBlackCodeWord(); setToBlack(bitOffset, number); bitOffset += number; currChangingElems[currIndex++] = bitOffset; } else { number = decodeBlackCodeWord(); setToBlack(bitOffset, number); bitOffset += number; currChangingElems[currIndex++] = bitOffset; number = decodeWhiteCodeWord(); bitOffset += number; currChangingElems[currIndex++] = bitOffset; } a0 = bitOffset; } else if (code <= 8) { // Vertical a1 = b1 + (code - 5); currChangingElems[currIndex++] = a1; // We write the current color till a1 - 1 pos, // since a1 is where the next color starts if (!isWhite) { setToBlack(bitOffset, a1 - bitOffset); } bitOffset = a0 = a1; isWhite = !isWhite; updatePointer(7 - bits); } else { ++fails; // Find the next one-dimensionally encoded line. int numLinesTested = 0; while (modeFlag != 1) { try { modeFlag = findNextLine(); numLinesTested++; } catch (Exception eofe) { return; } } lines += numLinesTested - 1; updatePointer(13); break; } } // Add the changing element beyond the current scanline for the // other color too currChangingElems[currIndex++] = bitOffset; changingElemSize = currIndex; } else { // modeFlag == 1 // 1D encoded scanline follows decodeNextScanline(); } lineBitNum += bitsPerScanline; lines++; } // while(lines < height) } public void decodeT6() { synchronized (lock) { int height = h; int a0, a1, b1, b2; int entry, code, bits; boolean isWhite; int currIndex; int temp[]; // Return values from getNextChangingElement int[] b = new int[2]; // uncompressedMode - have written some code for this, but this // has not been tested due to lack of test images using this optional // extension. This code is when code == 11. aastha 03/03/1999 // Local cached reference int[] cce = currChangingElems; // Assume invisible preceding row of all white pixels and insert // both black and white changing elements beyond the end of this // imaginary scanline. changingElemSize = 0; cce[changingElemSize++] = w; cce[changingElemSize++] = w; int bitOffset; for (int lines = 0; lines < height; lines++) { // a0 has to be set just before the start of the scanline. a0 = -1; isWhite = true; // Assign the changing elements of the previous scanline to // prevChangingElems and start putting this new scanline's // changing elements into the currChangingElems. temp = prevChangingElems; prevChangingElems = currChangingElems; cce = currChangingElems = temp; currIndex = 0; // Start decoding the scanline bitOffset = 0; // Reset search start position for getNextChangingElement lastChangingElement = 0; // Till one whole scanline is decoded while (bitOffset < w) { // Get the next changing element getNextChangingElement(a0, isWhite, b); b1 = b[0]; b2 = b[1]; // Get the next seven bits entry = nextLesserThan8Bits(7); // Run these through the 2DCodes table entry = twoDCodes[entry] & 0xff; // Get the code and the number of bits used up code = (entry & 0x78) >>> 3; bits = entry & 0x07; if (code == 0) { // Pass // We always assume WhiteIsZero format for fax. if (!isWhite) { if (b2 > w) { b2 = w; } setToBlack(bitOffset, b2 - bitOffset); } bitOffset = a0 = b2; // Set pointer to only consume the correct number of bits. updatePointer(7 - bits); } else if (code == 1) { // Horizontal // Set pointer to only consume the correct number of bits. updatePointer(7 - bits); // identify the next 2 alternating color codes. int number; if (isWhite) { // Following are white and black runs number = decodeWhiteCodeWord(); bitOffset += number; cce[currIndex++] = bitOffset; number = decodeBlackCodeWord(); if (number > w - bitOffset) { number = w - bitOffset; } setToBlack(bitOffset, number); bitOffset += number; cce[currIndex++] = bitOffset; } else { // First a black run and then a white run follows number = decodeBlackCodeWord(); if (number > w - bitOffset) { number = w - bitOffset; } setToBlack(bitOffset, number); bitOffset += number; cce[currIndex++] = bitOffset; number = decodeWhiteCodeWord(); bitOffset += number; cce[currIndex++] = bitOffset; } a0 = bitOffset; } else if (code <= 8) { // Vertical a1 = b1 + (code - 5); cce[currIndex++] = a1; // We write the current color till a1 - 1 pos, // since a1 is where the next color starts if (!isWhite) { if (a1 > w) { a1 = w; } setToBlack(bitOffset, a1 - bitOffset); } bitOffset = a0 = a1; isWhite = !isWhite; updatePointer(7 - bits); } else if (code == 11) { int entranceCode = nextLesserThan8Bits(3); int zeros = 0; boolean exit = false; while (!exit) { while (nextLesserThan8Bits(1) != 1) { zeros++; } if (zeros > 5) { // Exit code // Zeros before exit code zeros = zeros - 6; if (!isWhite && (zeros > 0)) { cce[currIndex++] = bitOffset; } // Zeros before the exit code bitOffset += zeros; if (zeros > 0) { // Some zeros have been written isWhite = true; } // Read in the bit which specifies the color of // the following run if (nextLesserThan8Bits(1) == 0) { if (!isWhite) { cce[currIndex++] = bitOffset; } isWhite = true; } else { if (isWhite) { cce[currIndex++] = bitOffset; } isWhite = false; } exit = true; } if (zeros == 5) { if (!isWhite) { cce[currIndex++] = bitOffset; } bitOffset += zeros; // Last thing written was white isWhite = true; } else { bitOffset += zeros; cce[currIndex++] = bitOffset; setToBlack(bitOffset, 1); ++bitOffset; // Last thing written was black isWhite = false; } } } } // while bitOffset < w // Add the changing element beyond the current scanline for the // other color too, if not already added previously if (currIndex <= w) cce[currIndex++] = bitOffset; // Number of changing elements in this scanline. changingElemSize = currIndex; lineBitNum += bitsPerScanline; } // for lines < height } } private void setToBlack(int bitNum, int numBits) { // bitNum is relative to current scanline so bump it by lineBitNum bitNum += lineBitNum; int lastBit = bitNum + numBits; int byteNum = bitNum >> 3; // Handle bits in first byte int shift = bitNum & 0x7; if (shift > 0) { int maskVal = 1 << (7 - shift); byte val = buffer[byteNum]; while (maskVal > 0 && bitNum < lastBit) { val |= (byte) maskVal; maskVal >>= 1; ++bitNum; } buffer[byteNum] = val; } // Fill in 8 bits at a time byteNum = bitNum >> 3; while (bitNum < lastBit - 7) { buffer[byteNum++] = (byte) 255; bitNum += 8; } // Fill in remaining bits while (bitNum < lastBit) { byteNum = bitNum >> 3; buffer[byteNum] |= (byte) (1 << (7 - (bitNum & 0x7))); ++bitNum; } } // Returns run length private int decodeWhiteCodeWord() { int current, entry, bits, isT, twoBits, code = -1; int runLength = 0; boolean isWhite = true; while (isWhite) { current = nextNBits(10); entry = white[current]; // Get the 3 fields from the entry isT = entry & 0x0001; bits = (entry >>> 1) & 0x0f; if (bits == 12) { // Additional Make up code // Get the next 2 bits twoBits = nextLesserThan8Bits(2); // Consolidate the 2 new bits and last 2 bits into 4 bits current = ((current << 2) & 0x000c) | twoBits; entry = additionalMakeup[current]; bits = (entry >>> 1) & 0x07; // 3 bits 0000 0111 code = (entry >>> 4) & 0x0fff; // 12 bits runLength += code; updatePointer(4 - bits); } else if (bits == 0) { // ERROR throw new RuntimeException("Error 0"); } else if (bits == 15) { // EOL throw new RuntimeException("Error 1"); } else { // 11 bits - 0000 0111 1111 1111 = 0x07ff code = (entry >>> 5) & 0x07ff; runLength += code; updatePointer(10 - bits); if (isT == 0) { isWhite = false; } } } return runLength; } // Returns run length private int decodeBlackCodeWord() { int current, entry, bits, isT, twoBits, code = -1; int runLength = 0; boolean isWhite = false; while (!isWhite) { current = nextLesserThan8Bits(4); entry = initBlack[current]; // Get the 3 fields from the entry isT = entry & 0x0001; bits = (entry >>> 1) & 0x000f; code = (entry >>> 5) & 0x07ff; if (code == 100) { current = nextNBits(9); entry = black[current]; // Get the 3 fields from the entry isT = entry & 0x0001; bits = (entry >>> 1) & 0x000f; code = (entry >>> 5) & 0x07ff; if (bits == 12) { // Additional makeup codes updatePointer(5); current = nextLesserThan8Bits(4); entry = additionalMakeup[current]; bits = (entry >>> 1) & 0x07; // 3 bits 0000 0111 code = (entry >>> 4) & 0x0fff; // 12 bits runLength += code; updatePointer(4 - bits); } else if (bits == 15) { // EOL code throw new RuntimeException("Error 2"); } else { runLength += code; updatePointer(9 - bits); if (isT == 0) { isWhite = true; } } } else if (code == 200) { // Is a Terminating code current = nextLesserThan8Bits(2); entry = twoBitBlack[current]; code = (entry >>> 5) & 0x07ff; runLength += code; bits = (entry >>> 1) & 0x0f; updatePointer(2 - bits); isWhite = true; } else { // Is a Terminating code runLength += code; updatePointer(4 - bits); isWhite = true; } } return runLength; } private int findNextLine() { // Set maximum and current bit index into the compressed data. int bitIndexMax = data.length * 8 - 1; int bitIndexMax12 = bitIndexMax - 12; int bitIndex = bytePointer * 8 + bitPointer; // Loop while at least 12 bits are available. while (bitIndex <= bitIndexMax12) { // Get the next 12 bits. int next12Bits = nextNBits(12); bitIndex += 12; // Loop while the 12 bits are not unity, i.e., while the EOL // has not been reached, and there is at least one bit left. while (next12Bits != 1 && bitIndex < bitIndexMax) { next12Bits = ((next12Bits & 0x000007ff) << 1) | (nextLesserThan8Bits(1) & 0x00000001); bitIndex++; } if (next12Bits == 1) { // now positioned just after EOL if (oneD == 1) { // two-dimensional coding if (bitIndex < bitIndexMax) { // check next bit against type of line being sought return nextLesserThan8Bits(1); } } else { return 1; } } } // EOL not found. throw new RuntimeException(); } private void getNextChangingElement(int a0, boolean isWhite, int[] ret) { // Local copies of instance variables int[] pce = this.prevChangingElems; int ces = this.changingElemSize; // If the previous match was at an odd element, we still // have to search the preceeding element. // int start = lastChangingElement & ~0x1; int start = lastChangingElement > 0 ? lastChangingElement - 1 : 0; if (isWhite) { start &= ~0x1; // Search even numbered elements } else { start |= 0x1; // Search odd numbered elements } int i = start; for (; i < ces; i += 2) { int temp = pce[i]; if (temp > a0) { lastChangingElement = i; ret[0] = temp; break; } } if (i + 1 < ces) { ret[1] = pce[i + 1]; } } private int nextNBits(int bitsToGet) { byte b, next, next2next; int l = data.length - 1; int bp = this.bytePointer; if (fillOrder == 1) { b = data[bp]; if (bp == l) { next = 0x00; next2next = 0x00; } else if ((bp + 1) == l) { next = data[bp + 1]; next2next = 0x00; } else { next = data[bp + 1]; next2next = data[bp + 2]; } } else if (fillOrder == 2) { b = flipTable[data[bp] & 0xff]; if (bp == l) { next = 0x00; next2next = 0x00; } else if ((bp + 1) == l) { next = flipTable[data[bp + 1] & 0xff]; next2next = 0x00; } else { next = flipTable[data[bp + 1] & 0xff]; next2next = flipTable[data[bp + 2] & 0xff]; } } else { throw new RuntimeException("Invalid FillOrder"); } int bitsLeft = 8 - bitPointer; int bitsFromNextByte = bitsToGet - bitsLeft; int bitsFromNext2NextByte = 0; if (bitsFromNextByte > 8) { bitsFromNext2NextByte = bitsFromNextByte - 8; bitsFromNextByte = 8; } bytePointer++; int i1 = (b & table1[bitsLeft]) << (bitsToGet - bitsLeft); int i2 = (next & table2[bitsFromNextByte]) >>> (8 - bitsFromNextByte); int i3 = 0; if (bitsFromNext2NextByte != 0) { i2 <<= bitsFromNext2NextByte; i3 = (next2next & table2[bitsFromNext2NextByte]) >>> (8 - bitsFromNext2NextByte); i2 |= i3; bytePointer++; bitPointer = bitsFromNext2NextByte; } else { if (bitsFromNextByte == 8) { bitPointer = 0; bytePointer++; } else { bitPointer = bitsFromNextByte; } } return i1 | i2; } private int nextLesserThan8Bits(int bitsToGet) { byte b, next; int l = data.length - 1; int bp = this.bytePointer; if (fillOrder == 1) { b = data[bp]; if (bp == l) { next = 0x00; } else { next = data[bp + 1]; } } else if (fillOrder == 2) { b = flipTable[data[bp] & 0xff]; if (bp == l) { next = 0x00; } else { next = flipTable[data[bp + 1] & 0xff]; } } else { throw new RuntimeException("Invalid FillOrder"); } int bitsLeft = 8 - bitPointer; int bitsFromNextByte = bitsToGet - bitsLeft; int shift = bitsLeft - bitsToGet; int i1, i2; if (shift >= 0) { i1 = (b & table1[bitsLeft]) >>> shift; bitPointer += bitsToGet; if (bitPointer == 8) { bitPointer = 0; bytePointer++; } } else { i1 = (b & table1[bitsLeft]) << (-shift); i2 = (next & table2[bitsFromNextByte]) >>> (8 - bitsFromNextByte); i1 |= i2; bytePointer++; bitPointer = bitsFromNextByte; } return i1; } // Move pointer backwards by given amount of bits private void updatePointer(int bitsToMoveBack) { if (bitsToMoveBack > 8) { bytePointer -= bitsToMoveBack / 8; bitsToMoveBack %= 8; } int i = bitPointer - bitsToMoveBack; if (i < 0) { bytePointer--; bitPointer = 8 + i; } else { bitPointer = i; } } }




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