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Java > Open Source Codes > org > apache > tools > bzip2 > CRC


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  *
17  */
18
19 /*
20  * This package is based on the work done by Keiron Liddle, Aftex Software
21  * <keiron@aftexsw.com> to whom the Ant project is very grateful for his
22  * great code.
23  */
24
25 package org.apache.tools.bzip2;
26
27 /**
28  * A simple class the hold and calculate the CRC for sanity checking
29  * of the data.
30  *
31  */
32 final class CRC {
33     static final int crc32Table[] = {
34         0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
35         0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
36         0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
37         0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
38         0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
39         0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
40         0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
41         0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
42         0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
43         0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
44         0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
45         0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
46         0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
47         0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
48         0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
49         0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
50         0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
51         0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
52         0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
53         0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
54         0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
55         0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
56         0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
57         0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
58         0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
59         0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
60         0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
61         0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
62         0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
63         0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
64         0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
65         0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
66         0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
67         0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
68         0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
69         0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
70         0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
71         0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
72         0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
73         0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
74         0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
75         0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
76         0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
77         0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
78         0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
79         0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
80         0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
81         0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
82         0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
83         0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
84         0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
85         0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
86         0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
87         0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
88         0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
89         0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
90         0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
91         0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
92         0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
93         0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
94         0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
95         0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
96         0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
97         0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
98     };
99
100     CRC() {
101         initialiseCRC();
102     }
103
104     void initialiseCRC() {
105         globalCrc = 0xffffffff;
106     }
107
108     int getFinalCRC() {
109         return ~globalCrc;
110     }
111
112     int getGlobalCRC() {
113         return globalCrc;
114     }
115
116     void setGlobalCRC(int newCrc) {
117         globalCrc = newCrc;
118     }
119
120     void updateCRC(int inCh) {
121         int temp = (globalCrc >> 24) ^ inCh;
122         if (temp < 0) {
123             temp = 256 + temp;
124         }
125         globalCrc = (globalCrc << 8) ^ CRC.crc32Table[temp];
126     }
127
128     void updateCRC(int inCh, int repeat) {
129         int globalCrcShadow = this.globalCrc;
130         while (repeat-- > 0) {
131             int temp = (globalCrcShadow >> 24) ^ inCh;
132             globalCrcShadow = (globalCrcShadow << 8) ^ crc32Table[(temp >= 0)
133                                                       ? temp
134                                                       : (temp + 256)];
135         }
136         this.globalCrc = globalCrcShadow;
137     }
138
139     int globalCrc;
140 }
141
142
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