View Javadoc

1   /*
2    * The Apache Software License, Version 1.1
3    *
4    * Copyright (c) 2001-2002 The Apache Software Foundation.  All rights
5    * reserved.
6    *
7    * Redistribution and use in source and binary forms, with or without
8    * modification, are permitted provided that the following conditions
9    * are met:
10   *
11   * 1. Redistributions of source code must retain the above copyright
12   *    notice, this list of conditions and the following disclaimer.
13   *
14   * 2. Redistributions in binary form must reproduce the above copyright
15   *    notice, this list of conditions and the following disclaimer in
16   *    the documentation and/or other materials provided with the
17   *    distribution.
18   *
19   * 3. The end-user documentation included with the redistribution, if
20   *    any, must include the following acknowlegement:
21   *       "This product includes software developed by the
22   *        Apache Software Foundation (http://www.apache.org/)."
23   *    Alternately, this acknowlegement may appear in the software itself,
24   *    if and wherever such third-party acknowlegements normally appear.
25   *
26   * 4. The names "Ant" and "Apache Software
27   *    Foundation" must not be used to endorse or promote products derived
28   *    from this software without prior written permission. For written
29   *    permission, please contact apache@apache.org.
30   *
31   * 5. Products derived from this software may not be called "Apache"
32   *    nor may "Apache" appear in their names without prior written
33   *    permission of the Apache Group.
34   *
35   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
36   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
37   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
38   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
39   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
41   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
42   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
43   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
44   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
45   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
46   * SUCH DAMAGE.
47   * ====================================================================
48   *
49   * This software consists of voluntary contributions made by many
50   * individuals on behalf of the Apache Software Foundation.  For more
51   * information on the Apache Software Foundation, please see
52   * <http://www.apache.org/>.
53   */
54  
55  /*
56   * This package is based on the work done by Keiron Liddle, Aftex Software
57   * <keiron@aftexsw.com> to whom the Ant project is very grateful for his
58   * great code.
59   */
60  
61  package com.jguild.jrpm.io.bzip2;
62  
63  /***
64   * A simple class the hold and calculate the CRC for sanity checking of the
65   * data.
66   * 
67   * @author <a href="mailto:keiron@aftexsw.com">Keiron Liddle</a>
68   */
69  class CRC {
70      private static int[] CRC32_TABLE = new int[] { 0x00000000, 0x04c11db7,
71              0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b, 0x1a864db2,
72              0x1e475005, 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
73              0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd, 0x4c11db70,
74              0x48d0c6c7, 0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b,
75              0x569796c2, 0x52568b75, 0x6a1936c8, 0x6ed82b7f, 0x639b0da6,
76              0x675a1011, 0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
77              0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039, 0x8b27c03c,
78              0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, 0xbe2b5b58, 0xbaea46ef,
79              0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea,
80              0xa06c0b5d, 0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
81              0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95, 0xf23a8028,
82              0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4, 0xe5ffeb43,
83              0xe8bccd9a, 0xec7dd02d, 0x34867077, 0x30476dc0, 0x3d044b19,
84              0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
85              0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13,
86              0x054bf6a4, 0x0808d07d, 0x0cc9cdca, 0x7897ab07, 0x7c56b6b0,
87              0x71159069, 0x75d48dde, 0x6b93dddb, 0x6f52c06c, 0x6211e6b5,
88              0x66d0fb02, 0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
89              0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba, 0xaca5c697,
90              0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc,
91              0xb6238b25, 0xb2e29692, 0x8aad2b2f, 0x8e6c3698, 0x832f1041,
92              0x87ee0df6, 0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
93              0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e, 0xf3b06b3b,
94              0xf771768c, 0xfa325055, 0xfef34de2, 0xc6bcf05f, 0xc27dede8,
95              0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34, 0xdc3abded,
96              0xd8fba05a, 0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
97              0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb, 0x4f040d56,
98              0x4bc510e1, 0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d,
99              0x558240e4, 0x51435d53, 0x251d3b9e, 0x21dc2629, 0x2c9f00f0,
100             0x285e1d47, 0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
101             0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff, 0x1011a0fa,
102             0x14d0bd4d, 0x19939b94, 0x1d528623, 0xf12f560e, 0xf5ee4bb9,
103             0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc,
104             0xef68060b, 0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
105             0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3, 0xbd3e8d7e,
106             0xb9ff90c9, 0xb4bcb610, 0xb07daba7, 0xae3afba2, 0xaafbe615,
107             0xa7b8c0cc, 0xa379dd7b, 0x9b3660c6, 0x9ff77d71, 0x92b45ba8,
108             0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
109             0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645,
110             0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c, 0x7b827d21, 0x7f436096,
111             0x7200464f, 0x76c15bf8, 0x68860bfd, 0x6c47164a, 0x61043093,
112             0x65c52d24, 0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
113             0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec, 0x3793a651,
114             0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a,
115             0x2d15ebe3, 0x29d4f654, 0xc5a92679, 0xc1683bce, 0xcc2b1d17,
116             0xc8ea00a0, 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
117             0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18, 0xf0a5bd1d,
118             0xf464a0aa, 0xf9278673, 0xfde69bc4, 0x89b8fd09, 0x8d79e0be,
119             0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662, 0x933eb0bb,
120             0x97ffad0c, 0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
121             0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4 };
122 
123     private int m_globalCrc;
124 
125     protected CRC() {
126         initialiseCRC();
127     }
128 
129     int getFinalCRC() {
130         return ~m_globalCrc;
131     }
132 
133     void initialiseCRC() {
134         m_globalCrc = 0xffffffff;
135     }
136 
137     void updateCRC(final int inCh) {
138         int temp = (m_globalCrc >> 24) ^ inCh;
139         if (temp < 0) {
140             temp = 256 + temp;
141         }
142         m_globalCrc = (m_globalCrc << 8) ^ CRC32_TABLE[temp];
143     }
144 }