276eccd37bfbaf26183a577ee33d2ff9875bafbd
[flac.git] / src / libFLAC / crc.c
1 /* libFLAC - Free Lossless Audio Coder library
2  * Copyright (C) 2000,2001  Josh Coalson
3  *
4  * This library is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Library General Public
6  * License as published by the Free Software Foundation; either
7  * version 2 of the License, or (at your option) any later version.
8  *
9  * This library is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12  * Library General Public License for more details.
13  *
14  * You should have received a copy of the GNU Library General Public
15  * License along with this library; if not, write to the
16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17  * Boston, MA  02111-1307, USA.
18  */
19
20 #include "private/crc.h"
21
22 byte FLAC__crc8(const byte *data, const unsigned len)
23 {
24         static byte const crc8_table_[256] = {
25                 0x00, 0x07, 0x0E, 0x09, 0x1C, 0x1B, 0x12, 0x15,
26                 0x38, 0x3F, 0x36, 0x31, 0x24, 0x23, 0x2A, 0x2D,
27                 0x70, 0x77, 0x7E, 0x79, 0x6C, 0x6B, 0x62, 0x65,
28                 0x48, 0x4F, 0x46, 0x41, 0x54, 0x53, 0x5A, 0x5D,
29                 0xE0, 0xE7, 0xEE, 0xE9, 0xFC, 0xFB, 0xF2, 0xF5,
30                 0xD8, 0xDF, 0xD6, 0xD1, 0xC4, 0xC3, 0xCA, 0xCD,
31                 0x90, 0x97, 0x9E, 0x99, 0x8C, 0x8B, 0x82, 0x85,
32                 0xA8, 0xAF, 0xA6, 0xA1, 0xB4, 0xB3, 0xBA, 0xBD,
33                 0xC7, 0xC0, 0xC9, 0xCE, 0xDB, 0xDC, 0xD5, 0xD2,
34                 0xFF, 0xF8, 0xF1, 0xF6, 0xE3, 0xE4, 0xED, 0xEA,
35                 0xB7, 0xB0, 0xB9, 0xBE, 0xAB, 0xAC, 0xA5, 0xA2,
36                 0x8F, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9D, 0x9A,
37                 0x27, 0x20, 0x29, 0x2E, 0x3B, 0x3C, 0x35, 0x32,
38                 0x1F, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0D, 0x0A,
39                 0x57, 0x50, 0x59, 0x5E, 0x4B, 0x4C, 0x45, 0x42,
40                 0x6F, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7D, 0x7A,
41                 0x89, 0x8E, 0x87, 0x80, 0x95, 0x92, 0x9B, 0x9C,
42                 0xB1, 0xB6, 0xBF, 0xB8, 0xAD, 0xAA, 0xA3, 0xA4,
43                 0xF9, 0xFE, 0xF7, 0xF0, 0xE5, 0xE2, 0xEB, 0xEC,
44                 0xC1, 0xC6, 0xCF, 0xC8, 0xDD, 0xDA, 0xD3, 0xD4,
45                 0x69, 0x6E, 0x67, 0x60, 0x75, 0x72, 0x7B, 0x7C,
46                 0x51, 0x56, 0x5F, 0x58, 0x4D, 0x4A, 0x43, 0x44,
47                 0x19, 0x1E, 0x17, 0x10, 0x05, 0x02, 0x0B, 0x0C,
48                 0x21, 0x26, 0x2F, 0x28, 0x3D, 0x3A, 0x33, 0x34,
49                 0x4E, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5C, 0x5B,
50                 0x76, 0x71, 0x78, 0x7F, 0x6A, 0x6D, 0x64, 0x63,
51                 0x3E, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2C, 0x2B,
52                 0x06, 0x01, 0x08, 0x0F, 0x1A, 0x1D, 0x14, 0x13,
53                 0xAE, 0xA9, 0xA0, 0xA7, 0xB2, 0xB5, 0xBC, 0xBB,
54                 0x96, 0x91, 0x98, 0x9F, 0x8A, 0x8D, 0x84, 0x83,
55                 0xDE, 0xD9, 0xD0, 0xD7, 0xC2, 0xC5, 0xCC, 0xCB,
56                 0xE6, 0xE1, 0xE8, 0xEF, 0xFA, 0xFD, 0xF4, 0xF3
57         };
58         unsigned i;
59         byte crc = 0;
60
61         for(i = 0; i < len; i++)
62                 crc = crc8_table_[crc ^ *data++];
63
64         return crc;
65 }