001: /*
002: * Licensed to the Apache Software Foundation (ASF) under one or more
003: * contributor license agreements. See the NOTICE file distributed with
004: * this work for additional information regarding copyright ownership.
005: * The ASF licenses this file to You under the Apache License, Version 2.0
006: * (the "License"); you may not use this file except in compliance with
007: * the License. You may obtain a copy of the License at
008: *
009: * http://www.apache.org/licenses/LICENSE-2.0
010: *
011: * Unless required by applicable law or agreed to in writing, software
012: * distributed under the License is distributed on an "AS IS" BASIS,
013: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014: * See the License for the specific language governing permissions and
015: * limitations under the License.
016: *
017: */
018:
019: /*
020: * This package is based on the work done by Keiron Liddle, Aftex Software
021: * <keiron@aftexsw.com> to whom the Ant project is very grateful for his
022: * great code.
023: */
024:
025: package org.apache.tools.bzip2;
026:
027: /**
028: * A simple class the hold and calculate the CRC for sanity checking
029: * of the data.
030: *
031: */
032: final class CRC {
033: static final int crc32Table[] = { 0x00000000, 0x04c11db7,
034: 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b, 0x1a864db2,
035: 0x1e475005, 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
036: 0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd, 0x4c11db70,
037: 0x48d0c6c7, 0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b,
038: 0x569796c2, 0x52568b75, 0x6a1936c8, 0x6ed82b7f, 0x639b0da6,
039: 0x675a1011, 0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
040: 0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039, 0x8b27c03c,
041: 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, 0xbe2b5b58, 0xbaea46ef,
042: 0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea,
043: 0xa06c0b5d, 0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
044: 0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95, 0xf23a8028,
045: 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4, 0xe5ffeb43,
046: 0xe8bccd9a, 0xec7dd02d, 0x34867077, 0x30476dc0, 0x3d044b19,
047: 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
048: 0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13,
049: 0x054bf6a4, 0x0808d07d, 0x0cc9cdca, 0x7897ab07, 0x7c56b6b0,
050: 0x71159069, 0x75d48dde, 0x6b93dddb, 0x6f52c06c, 0x6211e6b5,
051: 0x66d0fb02, 0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
052: 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba, 0xaca5c697,
053: 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc,
054: 0xb6238b25, 0xb2e29692, 0x8aad2b2f, 0x8e6c3698, 0x832f1041,
055: 0x87ee0df6, 0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
056: 0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e, 0xf3b06b3b,
057: 0xf771768c, 0xfa325055, 0xfef34de2, 0xc6bcf05f, 0xc27dede8,
058: 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34, 0xdc3abded,
059: 0xd8fba05a, 0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
060: 0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb, 0x4f040d56,
061: 0x4bc510e1, 0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d,
062: 0x558240e4, 0x51435d53, 0x251d3b9e, 0x21dc2629, 0x2c9f00f0,
063: 0x285e1d47, 0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
064: 0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff, 0x1011a0fa,
065: 0x14d0bd4d, 0x19939b94, 0x1d528623, 0xf12f560e, 0xf5ee4bb9,
066: 0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc,
067: 0xef68060b, 0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
068: 0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3, 0xbd3e8d7e,
069: 0xb9ff90c9, 0xb4bcb610, 0xb07daba7, 0xae3afba2, 0xaafbe615,
070: 0xa7b8c0cc, 0xa379dd7b, 0x9b3660c6, 0x9ff77d71, 0x92b45ba8,
071: 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
072: 0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645,
073: 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c, 0x7b827d21, 0x7f436096,
074: 0x7200464f, 0x76c15bf8, 0x68860bfd, 0x6c47164a, 0x61043093,
075: 0x65c52d24, 0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
076: 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec, 0x3793a651,
077: 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a,
078: 0x2d15ebe3, 0x29d4f654, 0xc5a92679, 0xc1683bce, 0xcc2b1d17,
079: 0xc8ea00a0, 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
080: 0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18, 0xf0a5bd1d,
081: 0xf464a0aa, 0xf9278673, 0xfde69bc4, 0x89b8fd09, 0x8d79e0be,
082: 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662, 0x933eb0bb,
083: 0x97ffad0c, 0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
084: 0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4 };
085:
086: CRC() {
087: initialiseCRC();
088: }
089:
090: void initialiseCRC() {
091: globalCrc = 0xffffffff;
092: }
093:
094: int getFinalCRC() {
095: return ~globalCrc;
096: }
097:
098: int getGlobalCRC() {
099: return globalCrc;
100: }
101:
102: void setGlobalCRC(int newCrc) {
103: globalCrc = newCrc;
104: }
105:
106: void updateCRC(int inCh) {
107: int temp = (globalCrc >> 24) ^ inCh;
108: if (temp < 0) {
109: temp = 256 + temp;
110: }
111: globalCrc = (globalCrc << 8) ^ CRC.crc32Table[temp];
112: }
113:
114: void updateCRC(int inCh, int repeat) {
115: int globalCrcShadow = this .globalCrc;
116: while (repeat-- > 0) {
117: int temp = (globalCrcShadow >> 24) ^ inCh;
118: globalCrcShadow = (globalCrcShadow << 8)
119: ^ crc32Table[(temp >= 0) ? temp : (temp + 256)];
120: }
121: this .globalCrc = globalCrcShadow;
122: }
123:
124: int globalCrc;
125: }
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