| Thomas Chou | 4f3391b | 2011-01-11 09:38:20 +0800 | [diff] [blame] | 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 <linux/types.h> |
| 9 | #include <linux/crc7.h> |
| 10 | |
| 11 | |
| 12 | /* Table for CRC-7 (polynomial x^7 + x^3 + 1) */ |
| 13 | const u8 crc7_syndrome_table[256] = { |
| 14 | 0x00, 0x09, 0x12, 0x1b, 0x24, 0x2d, 0x36, 0x3f, |
| 15 | 0x48, 0x41, 0x5a, 0x53, 0x6c, 0x65, 0x7e, 0x77, |
| 16 | 0x19, 0x10, 0x0b, 0x02, 0x3d, 0x34, 0x2f, 0x26, |
| 17 | 0x51, 0x58, 0x43, 0x4a, 0x75, 0x7c, 0x67, 0x6e, |
| 18 | 0x32, 0x3b, 0x20, 0x29, 0x16, 0x1f, 0x04, 0x0d, |
| 19 | 0x7a, 0x73, 0x68, 0x61, 0x5e, 0x57, 0x4c, 0x45, |
| 20 | 0x2b, 0x22, 0x39, 0x30, 0x0f, 0x06, 0x1d, 0x14, |
| 21 | 0x63, 0x6a, 0x71, 0x78, 0x47, 0x4e, 0x55, 0x5c, |
| 22 | 0x64, 0x6d, 0x76, 0x7f, 0x40, 0x49, 0x52, 0x5b, |
| 23 | 0x2c, 0x25, 0x3e, 0x37, 0x08, 0x01, 0x1a, 0x13, |
| 24 | 0x7d, 0x74, 0x6f, 0x66, 0x59, 0x50, 0x4b, 0x42, |
| 25 | 0x35, 0x3c, 0x27, 0x2e, 0x11, 0x18, 0x03, 0x0a, |
| 26 | 0x56, 0x5f, 0x44, 0x4d, 0x72, 0x7b, 0x60, 0x69, |
| 27 | 0x1e, 0x17, 0x0c, 0x05, 0x3a, 0x33, 0x28, 0x21, |
| 28 | 0x4f, 0x46, 0x5d, 0x54, 0x6b, 0x62, 0x79, 0x70, |
| 29 | 0x07, 0x0e, 0x15, 0x1c, 0x23, 0x2a, 0x31, 0x38, |
| 30 | 0x41, 0x48, 0x53, 0x5a, 0x65, 0x6c, 0x77, 0x7e, |
| 31 | 0x09, 0x00, 0x1b, 0x12, 0x2d, 0x24, 0x3f, 0x36, |
| 32 | 0x58, 0x51, 0x4a, 0x43, 0x7c, 0x75, 0x6e, 0x67, |
| 33 | 0x10, 0x19, 0x02, 0x0b, 0x34, 0x3d, 0x26, 0x2f, |
| 34 | 0x73, 0x7a, 0x61, 0x68, 0x57, 0x5e, 0x45, 0x4c, |
| 35 | 0x3b, 0x32, 0x29, 0x20, 0x1f, 0x16, 0x0d, 0x04, |
| 36 | 0x6a, 0x63, 0x78, 0x71, 0x4e, 0x47, 0x5c, 0x55, |
| 37 | 0x22, 0x2b, 0x30, 0x39, 0x06, 0x0f, 0x14, 0x1d, |
| 38 | 0x25, 0x2c, 0x37, 0x3e, 0x01, 0x08, 0x13, 0x1a, |
| 39 | 0x6d, 0x64, 0x7f, 0x76, 0x49, 0x40, 0x5b, 0x52, |
| 40 | 0x3c, 0x35, 0x2e, 0x27, 0x18, 0x11, 0x0a, 0x03, |
| 41 | 0x74, 0x7d, 0x66, 0x6f, 0x50, 0x59, 0x42, 0x4b, |
| 42 | 0x17, 0x1e, 0x05, 0x0c, 0x33, 0x3a, 0x21, 0x28, |
| 43 | 0x5f, 0x56, 0x4d, 0x44, 0x7b, 0x72, 0x69, 0x60, |
| 44 | 0x0e, 0x07, 0x1c, 0x15, 0x2a, 0x23, 0x38, 0x31, |
| 45 | 0x46, 0x4f, 0x54, 0x5d, 0x62, 0x6b, 0x70, 0x79 |
| 46 | }; |
| 47 | |
| 48 | /** |
| 49 | * crc7 - update the CRC7 for the data buffer |
| 50 | * @crc: previous CRC7 value |
| 51 | * @buffer: data pointer |
| 52 | * @len: number of bytes in the buffer |
| 53 | * Context: any |
| 54 | * |
| 55 | * Returns the updated CRC7 value. |
| 56 | */ |
| 57 | u8 crc7(u8 crc, const u8 *buffer, size_t len) |
| 58 | { |
| 59 | while (len--) |
| 60 | crc = crc7_byte(crc, *buffer++); |
| 61 | return crc; |
| 62 | } |