1/*
2 * libid3tag - ID3 tag manipulation library
3 * Copyright (C) 2000-2004 Underbit Technologies, Inc.
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18 *
19 * $Id: crc.c,v 1.11 2004/02/17 02:04:10 rob Exp $
20 */
21
22# ifdef HAVE_CONFIG_H
23#  include "config.h"
24# endif
25
26# include "global.h"
27
28# include "id3tag.h"
29# include "crc.h"
30
31static
32unsigned long const crc_table[256] = {
33  0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL,
34  0x076dc419L, 0x706af48fL, 0xe963a535L, 0x9e6495a3L,
35  0x0edb8832L, 0x79dcb8a4L, 0xe0d5e91eL, 0x97d2d988L,
36  0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L, 0x90bf1d91L,
37  0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
38  0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L,
39  0x136c9856L, 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL,
40  0x14015c4fL, 0x63066cd9L, 0xfa0f3d63L, 0x8d080df5L,
41
42  0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L, 0xa2677172L,
43  0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
44  0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L,
45  0x32d86ce3L, 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L,
46  0x26d930acL, 0x51de003aL, 0xc8d75180L, 0xbfd06116L,
47  0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L, 0xb8bda50fL,
48  0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
49  0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL,
50
51  0x76dc4190L, 0x01db7106L, 0x98d220bcL, 0xefd5102aL,
52  0x71b18589L, 0x06b6b51fL, 0x9fbfe4a5L, 0xe8b8d433L,
53  0x7807c9a2L, 0x0f00f934L, 0x9609a88eL, 0xe10e9818L,
54  0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
55  0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL,
56  0x6c0695edL, 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L,
57  0x65b0d9c6L, 0x12b7e950L, 0x8bbeb8eaL, 0xfcb9887cL,
58  0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L, 0xfbd44c65L,
59
60  0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
61  0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL,
62  0x4369e96aL, 0x346ed9fcL, 0xad678846L, 0xda60b8d0L,
63  0x44042d73L, 0x33031de5L, 0xaa0a4c5fL, 0xdd0d7cc9L,
64  0x5005713cL, 0x270241aaL, 0xbe0b1010L, 0xc90c2086L,
65  0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
66  0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L,
67  0x59b33d17L, 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL,
68
69  0xedb88320L, 0x9abfb3b6L, 0x03b6e20cL, 0x74b1d29aL,
70  0xead54739L, 0x9dd277afL, 0x04db2615L, 0x73dc1683L,
71  0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
72  0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L,
73  0xf00f9344L, 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL,
74  0xf762575dL, 0x806567cbL, 0x196c3671L, 0x6e6b06e7L,
75  0xfed41b76L, 0x89d32be0L, 0x10da7a5aL, 0x67dd4accL,
76  0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
77
78  0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L,
79  0xd1bb67f1L, 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL,
80  0xd80d2bdaL, 0xaf0a1b4cL, 0x36034af6L, 0x41047a60L,
81  0xdf60efc3L, 0xa867df55L, 0x316e8eefL, 0x4669be79L,
82  0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
83  0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL,
84  0xc5ba3bbeL, 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L,
85  0xc2d7ffa7L, 0xb5d0cf31L, 0x2cd99e8bL, 0x5bdeae1dL,
86
87  0x9b64c2b0L, 0xec63f226L, 0x756aa39cL, 0x026d930aL,
88  0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
89  0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L,
90  0x92d28e9bL, 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L,
91  0x86d3d2d4L, 0xf1d4e242L, 0x68ddb3f8L, 0x1fda836eL,
92  0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L, 0x18b74777L,
93  0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
94  0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L,
95
96  0xa00ae278L, 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L,
97  0xa7672661L, 0xd06016f7L, 0x4969474dL, 0x3e6e77dbL,
98  0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L, 0x37d83bf0L,
99  0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
100  0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L,
101  0xbad03605L, 0xcdd70693L, 0x54de5729L, 0x23d967bfL,
102  0xb3667a2eL, 0xc4614ab8L, 0x5d681b02L, 0x2a6f2b94L,
103  0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL, 0x2d02ef8dL
104};
105
106/*
107 * NAME:	crc->compute()
108 * DESCRIPTION:	calculate CRC-32 value (ISO 3309)
109 */
110unsigned long id3_crc_compute(id3_byte_t const *data, id3_length_t length)
111{
112  register unsigned long crc;
113
114  for (crc = 0xffffffffL; length >= 8; length -= 8) {
115    crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
116    crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
117    crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
118    crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
119    crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
120    crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
121    crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
122    crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
123  }
124
125  switch (length) {
126  case 7: crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
127  case 6: crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
128  case 5: crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
129  case 4: crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
130  case 3: crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
131  case 2: crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
132  case 1: crc = crc_table[(crc ^ *data++) & 0xff] ^ (crc >> 8);
133  case 0: break;
134  }
135
136  return crc ^ 0xffffffffL;
137}
138