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 } 63