1 /*
2 * crc7.c
3 *
4 * This source code is licensed under the GNU General Public License,
5 * Version 2. See the file COPYING for more details.
6 */
7
8 #include "crc7.h"
9
10 /* Table for CRC-7 (polynomial x^7 + x^3 + 1) */
11 const unsigned char crc7_syndrome_table[256] = {
12 0x00, 0x09, 0x12, 0x1b, 0x24, 0x2d, 0x36, 0x3f,
13 0x48, 0x41, 0x5a, 0x53, 0x6c, 0x65, 0x7e, 0x77,
14 0x19, 0x10, 0x0b, 0x02, 0x3d, 0x34, 0x2f, 0x26,
15 0x51, 0x58, 0x43, 0x4a, 0x75, 0x7c, 0x67, 0x6e,
16 0x32, 0x3b, 0x20, 0x29, 0x16, 0x1f, 0x04, 0x0d,
17 0x7a, 0x73, 0x68, 0x61, 0x5e, 0x57, 0x4c, 0x45,
18 0x2b, 0x22, 0x39, 0x30, 0x0f, 0x06, 0x1d, 0x14,
19 0x63, 0x6a, 0x71, 0x78, 0x47, 0x4e, 0x55, 0x5c,
20 0x64, 0x6d, 0x76, 0x7f, 0x40, 0x49, 0x52, 0x5b,
21 0x2c, 0x25, 0x3e, 0x37, 0x08, 0x01, 0x1a, 0x13,
22 0x7d, 0x74, 0x6f, 0x66, 0x59, 0x50, 0x4b, 0x42,
23 0x35, 0x3c, 0x27, 0x2e, 0x11, 0x18, 0x03, 0x0a,
24 0x56, 0x5f, 0x44, 0x4d, 0x72, 0x7b, 0x60, 0x69,
25 0x1e, 0x17, 0x0c, 0x05, 0x3a, 0x33, 0x28, 0x21,
26 0x4f, 0x46, 0x5d, 0x54, 0x6b, 0x62, 0x79, 0x70,
27 0x07, 0x0e, 0x15, 0x1c, 0x23, 0x2a, 0x31, 0x38,
28 0x41, 0x48, 0x53, 0x5a, 0x65, 0x6c, 0x77, 0x7e,
29 0x09, 0x00, 0x1b, 0x12, 0x2d, 0x24, 0x3f, 0x36,
30 0x58, 0x51, 0x4a, 0x43, 0x7c, 0x75, 0x6e, 0x67,
31 0x10, 0x19, 0x02, 0x0b, 0x34, 0x3d, 0x26, 0x2f,
32 0x73, 0x7a, 0x61, 0x68, 0x57, 0x5e, 0x45, 0x4c,
33 0x3b, 0x32, 0x29, 0x20, 0x1f, 0x16, 0x0d, 0x04,
34 0x6a, 0x63, 0x78, 0x71, 0x4e, 0x47, 0x5c, 0x55,
35 0x22, 0x2b, 0x30, 0x39, 0x06, 0x0f, 0x14, 0x1d,
36 0x25, 0x2c, 0x37, 0x3e, 0x01, 0x08, 0x13, 0x1a,
37 0x6d, 0x64, 0x7f, 0x76, 0x49, 0x40, 0x5b, 0x52,
38 0x3c, 0x35, 0x2e, 0x27, 0x18, 0x11, 0x0a, 0x03,
39 0x74, 0x7d, 0x66, 0x6f, 0x50, 0x59, 0x42, 0x4b,
40 0x17, 0x1e, 0x05, 0x0c, 0x33, 0x3a, 0x21, 0x28,
41 0x5f, 0x56, 0x4d, 0x44, 0x7b, 0x72, 0x69, 0x60,
42 0x0e, 0x07, 0x1c, 0x15, 0x2a, 0x23, 0x38, 0x31,
43 0x46, 0x4f, 0x54, 0x5d, 0x62, 0x6b, 0x70, 0x79
44 };
45
fio_crc7(const unsigned char * buffer,unsigned int len)46 unsigned char fio_crc7(const unsigned char *buffer, unsigned int len)
47 {
48 unsigned char crc = 0;
49
50 while (len--)
51 crc = crc7_byte(crc, *buffer++);
52 return crc;
53 }
54