1*4882a593Smuzhiyun /*
2*4882a593Smuzhiyun * crc7.c
3*4882a593Smuzhiyun *
4*4882a593Smuzhiyun * This source code is licensed under the GNU General Public License,
5*4882a593Smuzhiyun * Version 2. See the file COPYING for more details.
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun #include <linux/types.h>
9*4882a593Smuzhiyun #include <linux/crc7.h>
10*4882a593Smuzhiyun
11*4882a593Smuzhiyun
12*4882a593Smuzhiyun /* Table for CRC-7 (polynomial x^7 + x^3 + 1) */
13*4882a593Smuzhiyun const u8 crc7_syndrome_table[256] = {
14*4882a593Smuzhiyun 0x00, 0x09, 0x12, 0x1b, 0x24, 0x2d, 0x36, 0x3f,
15*4882a593Smuzhiyun 0x48, 0x41, 0x5a, 0x53, 0x6c, 0x65, 0x7e, 0x77,
16*4882a593Smuzhiyun 0x19, 0x10, 0x0b, 0x02, 0x3d, 0x34, 0x2f, 0x26,
17*4882a593Smuzhiyun 0x51, 0x58, 0x43, 0x4a, 0x75, 0x7c, 0x67, 0x6e,
18*4882a593Smuzhiyun 0x32, 0x3b, 0x20, 0x29, 0x16, 0x1f, 0x04, 0x0d,
19*4882a593Smuzhiyun 0x7a, 0x73, 0x68, 0x61, 0x5e, 0x57, 0x4c, 0x45,
20*4882a593Smuzhiyun 0x2b, 0x22, 0x39, 0x30, 0x0f, 0x06, 0x1d, 0x14,
21*4882a593Smuzhiyun 0x63, 0x6a, 0x71, 0x78, 0x47, 0x4e, 0x55, 0x5c,
22*4882a593Smuzhiyun 0x64, 0x6d, 0x76, 0x7f, 0x40, 0x49, 0x52, 0x5b,
23*4882a593Smuzhiyun 0x2c, 0x25, 0x3e, 0x37, 0x08, 0x01, 0x1a, 0x13,
24*4882a593Smuzhiyun 0x7d, 0x74, 0x6f, 0x66, 0x59, 0x50, 0x4b, 0x42,
25*4882a593Smuzhiyun 0x35, 0x3c, 0x27, 0x2e, 0x11, 0x18, 0x03, 0x0a,
26*4882a593Smuzhiyun 0x56, 0x5f, 0x44, 0x4d, 0x72, 0x7b, 0x60, 0x69,
27*4882a593Smuzhiyun 0x1e, 0x17, 0x0c, 0x05, 0x3a, 0x33, 0x28, 0x21,
28*4882a593Smuzhiyun 0x4f, 0x46, 0x5d, 0x54, 0x6b, 0x62, 0x79, 0x70,
29*4882a593Smuzhiyun 0x07, 0x0e, 0x15, 0x1c, 0x23, 0x2a, 0x31, 0x38,
30*4882a593Smuzhiyun 0x41, 0x48, 0x53, 0x5a, 0x65, 0x6c, 0x77, 0x7e,
31*4882a593Smuzhiyun 0x09, 0x00, 0x1b, 0x12, 0x2d, 0x24, 0x3f, 0x36,
32*4882a593Smuzhiyun 0x58, 0x51, 0x4a, 0x43, 0x7c, 0x75, 0x6e, 0x67,
33*4882a593Smuzhiyun 0x10, 0x19, 0x02, 0x0b, 0x34, 0x3d, 0x26, 0x2f,
34*4882a593Smuzhiyun 0x73, 0x7a, 0x61, 0x68, 0x57, 0x5e, 0x45, 0x4c,
35*4882a593Smuzhiyun 0x3b, 0x32, 0x29, 0x20, 0x1f, 0x16, 0x0d, 0x04,
36*4882a593Smuzhiyun 0x6a, 0x63, 0x78, 0x71, 0x4e, 0x47, 0x5c, 0x55,
37*4882a593Smuzhiyun 0x22, 0x2b, 0x30, 0x39, 0x06, 0x0f, 0x14, 0x1d,
38*4882a593Smuzhiyun 0x25, 0x2c, 0x37, 0x3e, 0x01, 0x08, 0x13, 0x1a,
39*4882a593Smuzhiyun 0x6d, 0x64, 0x7f, 0x76, 0x49, 0x40, 0x5b, 0x52,
40*4882a593Smuzhiyun 0x3c, 0x35, 0x2e, 0x27, 0x18, 0x11, 0x0a, 0x03,
41*4882a593Smuzhiyun 0x74, 0x7d, 0x66, 0x6f, 0x50, 0x59, 0x42, 0x4b,
42*4882a593Smuzhiyun 0x17, 0x1e, 0x05, 0x0c, 0x33, 0x3a, 0x21, 0x28,
43*4882a593Smuzhiyun 0x5f, 0x56, 0x4d, 0x44, 0x7b, 0x72, 0x69, 0x60,
44*4882a593Smuzhiyun 0x0e, 0x07, 0x1c, 0x15, 0x2a, 0x23, 0x38, 0x31,
45*4882a593Smuzhiyun 0x46, 0x4f, 0x54, 0x5d, 0x62, 0x6b, 0x70, 0x79
46*4882a593Smuzhiyun };
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun /**
49*4882a593Smuzhiyun * crc7 - update the CRC7 for the data buffer
50*4882a593Smuzhiyun * @crc: previous CRC7 value
51*4882a593Smuzhiyun * @buffer: data pointer
52*4882a593Smuzhiyun * @len: number of bytes in the buffer
53*4882a593Smuzhiyun * Context: any
54*4882a593Smuzhiyun *
55*4882a593Smuzhiyun * Returns the updated CRC7 value.
56*4882a593Smuzhiyun */
crc7(u8 crc,const u8 * buffer,size_t len)57*4882a593Smuzhiyun u8 crc7(u8 crc, const u8 *buffer, size_t len)
58*4882a593Smuzhiyun {
59*4882a593Smuzhiyun while (len--)
60*4882a593Smuzhiyun crc = crc7_byte(crc, *buffer++);
61*4882a593Smuzhiyun return crc;
62*4882a593Smuzhiyun }
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