/*
* Based on the SUN code (see license beyond) changes are made to handle CCITTFax encoded
* data in a PDF image. This may or may not apply to real world CCITT documents.
*
* Copyright (c) 2007, intarsys consulting GmbH
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions 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 intarsys nor the names of its contributors may be used
* to endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Copyright (c) 2001 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:
*
* -Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution in binary form must reproduct 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 AND ITS LICENSORS SHALL NOT BE
* LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
* OR DISTRIBUTING THE 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 SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that Software is not designed,licensed or intended for use in
* the design, construction, operation or maintenance of any nuclear facility.
*/
package org.icepdf.core.pobjects.filters;
public class CCITTFaxDecoder {
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 = {0, -128, 64, -64, 32, -96, 96, -32, 16, -112,
80, -48, 48, -80, 112, -16, 8, -120, 72, -56, 40, -88, 104, -24,
24, -104, 88, -40, 56, -72, 120, -8, 4, -124, 68, -60, 36, -92,
100, -28, 20, -108, 84, -44, 52, -76, 116, -12, 12, -116, 76, -52,
44, -84, 108, -20, 28, -100, 92, -36, 60, -68, 124, -4, 2, -126,
66, -62, 34, -94, 98, -30, 18, -110, 82, -46, 50, -78, 114, -14,
10, -118, 74, -54, 42, -86, 106, -22, 26, -102, 90, -38, 58, -70,
122, -6, 6, -122, 70, -58, 38, -90, 102, -26, 22, -106, 86, -42,
54, -74, 118, -10, 14, -114, 78, -50, 46, -82, 110, -18, 30, -98,
94, -34, 62, -66, 126, -2, 1, -127, 65, -63, 33, -95, 97, -31, 17,
-111, 81, -47, 49, -79, 113, -15, 9, -119, 73, -55, 41, -87, 105,
-23, 25, -103, 89, -39, 57, -71, 121, -7, 5, -123, 69, -59, 37,
-91, 101, -27, 21, -107, 85, -43, 53, -75, 117, -11, 13, -115, 77,
-51, 45, -83, 109, -19, 29, -99, 93, -35, 61, -67, 125, -3, 3,
-125, 67, -61, 35, -93, 99, -29, 19, -109, 83, -45, 51, -77, 115,
-13, 11, -117, 75, -53, 43, -85, 107, -21, 27, -101, 91, -37, 59,
-69, 123, -5, 7, -121, 71, -57, 39, -89, 103, -25, 23, -105, 87,
-41, 55, -73, 119, -9, 15, -113, 79, -49, 47, -81, 111, -17, 31,
-97, 95, -33, 63, -65, 127, -1,};
// 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};
// 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,};
private int bitPointer;
private int bytePointer;
private byte[] data;
private int w;
private boolean align = false;
private int fillOrder;
// 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 boolean fillBits = false;
/**
* @param fillOrder The fill order of the compressed data bytes.
* @param w
* @param h
*/
public CCITTFaxDecoder(int fillOrder, int w, int h) {
this.fillOrder = fillOrder;
this.w = w;
this.bitPointer = 0;
this.bytePointer = 0;
this.prevChangingElems = new int[w + 1];
this.currChangingElems = new int[w + 1];
}
private boolean align() {
if (align && bitPointer != 0) {
bytePointer++;
bitPointer = 0;
return true;
}
return false;
}
protected boolean consumeEOL() {
// Get the next 12 bits.
int next12Bits = nextNBits(12);
if (next12Bits == 1) {
// EOL found & consumed
return true;
}
// no EOL - unread and return
updatePointer(12);
return false;
}
// Returns run length
private int decodeBlackCodeWord() {
int current;
int entry;
int bits;
int isT;
int 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(
"EOL code word encountered in Black run."); //$NON-NLS-1$
} 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;
}
protected void decodeNextScanline(byte[] buffer, int lineOffset,
int bitOffset) {
int bits = 0;
int code = 0;
int isT = 0;
int current;
int entry;
int twoBits;
boolean isWhite = true;
// Initialize starting of the changing elements array
changingElemSize = 0;
// While scanline not complete
while (bitOffset < w) {
while (isWhite) {
// 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
throw new RuntimeException("Invalid code encountered.");
} else if (bits == 15) {
// EOL recover
// move bits back...
updatePointer(10);
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 so
// advance to next byte boundary for compression = 2.
if (bitOffset == w) {
align();
break;
}
while (!isWhite) {
// 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(buffer, lineOffset, bitOffset, code);
bitOffset += code;
updatePointer(4 - bits);
} else if (bits == 15) {
// EOL recover
// unread bits ???
updatePointer(9);
return;
} else {
setToBlack(buffer, lineOffset, 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(buffer, lineOffset, bitOffset, code);
bitOffset += code;
updatePointer(2 - bits);
isWhite = true;
currChangingElems[changingElemSize++] = bitOffset;
} else {
// Is a Terminating code
setToBlack(buffer, lineOffset, bitOffset, code);
bitOffset += code;
updatePointer(4 - bits);
isWhite = true;
currChangingElems[changingElemSize++] = bitOffset;
}
}
// Check whether this run completed one width
if (bitOffset == w) {
align();
break;
}
}
currChangingElems[changingElemSize++] = bitOffset;
}
// One-dimensional decoding methods
public void decodeT41D(byte[] buffer, byte[] compData, int startX,
int height) {
this.data = compData;
int scanlineStride = (w + 7) / 8;
bitPointer = 0;
bytePointer = 0;
int lineOffset = 0;
for (int i = 0; i < height; i++) {
consumeEOL();
decodeNextScanline(buffer, lineOffset, startX);
lineOffset += scanlineStride;
}
}
// Two-dimensional decoding methods
public void decodeT42D(byte[] buffer, byte[] compData, int startX,
int height) {
this.data = compData;
int scanlineStride = (w + 7) / 8;
bitPointer = 0;
bytePointer = 0;
int a0;
int a1;
int b1;
int b2;
int[] b = new int[2];
int entry;
int code;
int bits;
boolean isWhite;
int currIndex = 0;
int[] temp;
// The data must start with an EOL code
if (readEOL(true) != 1) {
throw new RuntimeException("First scanline must be 1D encoded."); //$NON-NLS-1$
}
int lineOffset = 0;
int bitOffset;
// Then the 1D encoded scanline data will occur, changing elements
// array gets set.
decodeNextScanline(buffer, lineOffset, startX);
lineOffset += scanlineStride;
for (int lines = 1; lines < height; lines++) {
// Every line must begin with an EOL followed by a bit which
// indicates whether the following scanline is 1D or 2D encoded.
if (readEOL(false) == 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 = startX;
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(buffer, lineOffset, 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(buffer, lineOffset, bitOffset, number);
bitOffset += number;
currChangingElems[currIndex++] = bitOffset;
} else {
number = decodeBlackCodeWord();
setToBlack(buffer, lineOffset, 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(buffer, lineOffset, bitOffset, a1
- bitOffset);
}
bitOffset = a0 = a1;
isWhite = !isWhite;
updatePointer(7 - bits);
} else {
throw new RuntimeException(
"Invalid code encountered while decoding 2D group 3 compressed data."); //$NON-NLS-1$
}
}
// Add the changing element beyond the current scanline for the
// other color too
currChangingElems[currIndex++] = bitOffset;
changingElemSize = currIndex;
} else {
// 1D encoded scanline follows
decodeNextScanline(buffer, lineOffset, startX);
}
lineOffset += scanlineStride;
}
}
public void decodeT6(byte[] buffer, byte[] compData, int startX, int height) {
this.data = compData;
int scanlineStride = (w + 7) / 8;
bitPointer = 0;
bytePointer = 0;
int a0;
int a1;
int b1;
int b2;
int entry;
int code;
int 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
// 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 lineOffset = 0;
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 at startX in the raster
bitOffset = startX;
// 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(buffer, lineOffset, 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(buffer, lineOffset, 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(buffer, lineOffset, 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(buffer, lineOffset, bitOffset, a1
- bitOffset);
}
bitOffset = a0 = a1;
isWhite = !isWhite;
updatePointer(7 - bits);
} else if (code == 11) {
if (nextLesserThan8Bits(3) != 7) {
throw new RuntimeException(
"Invalid code encountered while decoding 2D group 4 compressed data."); //$NON-NLS-1$
}
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(buffer, lineOffset, bitOffset, 1);
++bitOffset;
// Last thing written was black
isWhite = false;
}
}
} else {
// break line - seems to be a common failure
// unread
updatePointer(7 - bits);
// and mark lines as complete
bitOffset = w;
// throw new RuntimeException(
// "Invalid code encountered while decoding 2D group 4
// compressed data."); //$NON-NLS-1$
}
}
align();
// Add the changing element beyond the current scanline for the
// other color too
// make sure that the index does not exceed the bounds of the array
if (currIndex <= w) {
cce[currIndex++] = bitOffset;
}
// Number of changing elements in this scanline.
changingElemSize = currIndex;
lineOffset += scanlineStride;
}
}
// Returns run length
private int decodeWhiteCodeWord() {
int current;
int entry;
int bits;
int isT;
int twoBits;
int 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("Invalid code encountered."); //$NON-NLS-1$
} else if (bits == 15) { // EOL
throw new RuntimeException(
"EOL code word encountered in White run."); //$NON-NLS-1$
} else {
// 11 bits - 0000 0111 1111 1111 = 0x07ff
code = (entry >>> 5) & 0x07ff;
runLength += code;
updatePointer(10 - bits);
if (isT == 0) {
isWhite = false;
}
}
}
return runLength;
}
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
}
ret[0] = w;
ret[1] = w;
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];
}
}
public boolean isAlign() {
return align;
}
public boolean isFillBits() {
return fillBits;
}
private int nextLesserThan8Bits(int bitsToGet) {
byte b;
byte 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("tag must be either 1 or 2."); //$NON-NLS-1$
}
int bitsLeft = 8 - bitPointer;
int bitsFromNextByte = bitsToGet - bitsLeft;
int shift = bitsLeft - bitsToGet;
int i1;
int 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;
}
private int nextNBits(int bitsToGet) {
byte b;
byte next;
byte 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("tag must be either 1 or 2."); //$NON-NLS-1$
}
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;
}
}
int i = i1 | i2;
return i;
}
private int readEOL(boolean isFirstEOL) {
// Seek to the next EOL.
if (!seekEOL()) {
throw new RuntimeException("EOL not found");
}
if (!fillBits) {
int next12Bits = nextNBits(12);
if (isFirstEOL && (next12Bits == 0)) {
// Might have the case of EOL padding being used even
// though it was not flagged.
// This was observed to be the case in TIFFs produced
// by a well known vendor who shall remain nameless.
if (nextNBits(4) == 1) {
// EOL must be padded: reset the fillBits flag.
fillBits = true;
return 1;
}
}
if (next12Bits != 1) {
throw new RuntimeException(
"Scanline must begin with EOL code word."); //$NON-NLS-1$
}
} else {
// First EOL code word xxxx 0000 0000 0001 will occur
// As many fill bits will be present as required to make
// the EOL code of 12 bits end on a byte boundary.
int bitsLeft = 8 - bitPointer;
if (nextNBits(bitsLeft) != 0) {
throw new RuntimeException(
"All fill bits preceding EOL code must be 0."); //$NON-NLS-1$
}
// If the number of bitsLeft is less than 8, then to have a 12
// bit EOL sequence, two more bytes are certainly going to be
// required. The first of them has to be all zeros, so ensure
// that.
if (bitsLeft < 4) {
if (nextNBits(8) != 0) {
throw new RuntimeException(
"All fill bits preceding EOL code must be 0."); //$NON-NLS-1$
}
}
//
// Some encoders under Group 3 Fax compression 1D writes TIFF
// files without the fill bits, but say otherwise.
// Need to check for this here.
//
int next8 = nextNBits(8);
if (isFirstEOL && (next8 & 0xf0) == 0x10) {
//
// Fill bits are not actually used despite what the flag
// says. So switch fillBits off and then rewind so that
// only 12 bits have effectively been read.
//
fillBits = false;
updatePointer(4);
} else {
//
// This is the normal case.
// There might be a random number of fill bytes with 0s, so
// loop till the EOL of 0000 0001 is found, as long as all
// the bytes preceding it are 0's.
//
while (next8 != 1) {
// If not all zeros
if (next8 != 0) {
throw new RuntimeException("0 bits expected before EOL");
}
next8 = nextNBits(8);
}
}
}
// The next one bit signifies 1D/2D encoding of next line.
return nextLesserThan8Bits(1);
}
// Seeks to the next EOL in the compressed bitstream.
// Returns 'true' if and only if an EOL is found; if 'false'
// is returned it may be inferred that the EOF was reached first.
private boolean seekEOL() {
// Set maximum and current bit index into the compressed data.
int bitIndexMax = data.length * 8 - 1;
int bitIndex = bytePointer * 8 + bitPointer;
// Loop while at least 12 bits are available.
while (bitIndex <= bitIndexMax - 12) {
// 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 EOL reached, rewind the pointers and return 'true'.
if (next12Bits == 1) {
updatePointer(12);
return true;
}
}
// EOL not found: return 'false'.
return false;
}
public void setAlign(boolean align) {
this.align = align;
}
public void setFillBits(boolean fillBits) {
this.fillBits = fillBits;
}
private void setToBlack(byte[] buffer, int lineOffset, int bitOffset,
int numBits) {
int bitNum = (8 * lineOffset) + bitOffset;
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 |= 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] |= (1 << (7 - (bitNum & 0x7)));
++bitNum;
}
}
// 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;
}
}
}