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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   * http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.apache.commons.compress.compressors.bzip2;
20  
21  /**
22   * A simple class the hold and calculate the CRC for sanity checking of the
23   * data.
24   * @NotThreadSafe
25   */
26  class CRC {
27      private static final int crc32Table[] = {
28              0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
29              0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
30              0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
31              0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
32              0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
33              0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
34              0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
35              0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
36              0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
37              0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
38              0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
39              0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
40              0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
41              0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
42              0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
43              0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
44              0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
45              0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
46              0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
47              0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
48              0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
49              0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
50              0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
51              0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
52              0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
53              0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
54              0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
55              0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
56              0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
57              0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
58              0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
59              0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
60              0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
61              0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
62              0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
63              0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
64              0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
65              0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
66              0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
67              0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
68              0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
69              0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
70              0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
71              0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
72              0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
73              0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
74              0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
75              0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
76              0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
77              0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
78              0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
79              0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
80              0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
81              0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
82              0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
83              0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
84              0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
85              0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
86              0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
87              0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
88              0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
89              0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
90              0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
91              0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
92          };
93  
94          CRC() {
95              initialiseCRC();
96          }
97  
98          void initialiseCRC() {
99              globalCrc = 0xffffffff;
100         }
101 
102         int getFinalCRC() {
103             return ~globalCrc;
104         }
105 
106         int getGlobalCRC() {
107             return globalCrc;
108         }
109 
110         void setGlobalCRC(int newCrc) {
111             globalCrc = newCrc;
112         }
113 
114         void updateCRC(int inCh) {
115             int temp = (globalCrc >> 24) ^ inCh;
116             if (temp < 0) {
117                 temp = 256 + temp;
118             }
119             globalCrc = (globalCrc << 8) ^ CRC.crc32Table[temp];
120         }
121 
122         void updateCRC(int inCh, int repeat) {
123             int globalCrcShadow = this.globalCrc;
124             while (repeat-- > 0) {
125                 int temp = (globalCrcShadow >> 24) ^ inCh;
126                 globalCrcShadow = (globalCrcShadow << 8) ^ crc32Table[(temp >= 0)
127                                                           ? temp
128                                                           : (temp + 256)];
129             }
130             this.globalCrc = globalCrcShadow;
131         }
132 
133         private int globalCrc;
134 }