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Tom Rini83d290c2018-05-06 17:58:06 -04001// SPDX-License-Identifier: eCos-2.0
Wolfgang Denkcf48eb92006-04-16 10:51:58 +02002/*
3 *==========================================================================
4 *
5 * crc16.c
6 *
7 * 16 bit CRC with polynomial x^16+x^12+x^5+1
8 *
9 *==========================================================================
Wolfgang Denkcf48eb92006-04-16 10:51:58 +020010 *#####DESCRIPTIONBEGIN####
11 *
12 * Author(s): gthomas
13 * Contributors: gthomas,asl
14 * Date: 2001-01-31
15 * Purpose:
16 * Description:
17 *
18 * This code is part of eCos (tm).
19 *
20 *####DESCRIPTIONEND####
21 *
22 *==========================================================================
23 */
Markus Klotzbuecherf2841d32006-03-30 13:40:55 +020024
25#include "crc.h"
26
Wolfgang Denkcf48eb92006-04-16 10:51:58 +020027/* Table of CRC constants - implements x^16+x^12+x^5+1 */
Markus Klotzbuecherf2841d32006-03-30 13:40:55 +020028static const uint16_t crc16_tab[] = {
Stefan Roese71091572016-03-03 09:34:11 +010029 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
30 0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
31 0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
32 0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
33 0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
34 0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
35 0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
36 0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
37 0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
38 0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
39 0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
40 0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
41 0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
42 0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
43 0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
44 0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
45 0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
46 0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
47 0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
48 0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
49 0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
50 0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
51 0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
52 0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
53 0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
54 0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
55 0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
56 0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
57 0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
58 0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
59 0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
60 0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0,
Markus Klotzbuecherf2841d32006-03-30 13:40:55 +020061};
62
Stefan Roeseecb57f62016-03-03 09:34:12 +010063uint16_t crc16_ccitt(uint16_t crc_start, unsigned char *buf, int len)
Markus Klotzbuecherf2841d32006-03-30 13:40:55 +020064{
Stefan Roese71091572016-03-03 09:34:11 +010065 int i;
66 uint16_t cksum;
Markus Klotzbuecherf2841d32006-03-30 13:40:55 +020067
Stefan Roeseecb57f62016-03-03 09:34:12 +010068 cksum = crc_start;
Stefan Roese71091572016-03-03 09:34:11 +010069 for (i = 0; i < len; i++)
70 cksum = crc16_tab[((cksum>>8) ^ *buf++) & 0xff] ^ (cksum << 8);
71
72 return cksum;
Markus Klotzbuecherf2841d32006-03-30 13:40:55 +020073}