1 /*
2 * Copyright (c) 2017 Intel Corporation.
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 */
6
7 #include <zephyr/sys/crc.h>
8
crc16(uint16_t poly,uint16_t seed,const uint8_t * src,size_t len)9 uint16_t crc16(uint16_t poly, uint16_t seed, const uint8_t *src, size_t len)
10 {
11 uint16_t crc = seed;
12 size_t i, j;
13
14 for (i = 0; i < len; i++) {
15 crc ^= (uint16_t)(src[i] << 8U);
16
17 for (j = 0; j < 8; j++) {
18 if (crc & 0x8000UL) {
19 crc = (crc << 1U) ^ poly;
20 } else {
21 crc = crc << 1U;
22 }
23 }
24 }
25
26
27 return crc;
28 }
29
crc16_reflect(uint16_t poly,uint16_t seed,const uint8_t * src,size_t len)30 uint16_t crc16_reflect(uint16_t poly, uint16_t seed, const uint8_t *src, size_t len)
31 {
32 uint16_t crc = seed;
33 size_t i, j;
34
35 for (i = 0; i < len; i++) {
36 crc ^= (uint16_t)src[i];
37
38 for (j = 0; j < 8; j++) {
39 if (crc & 0x0001UL) {
40 crc = (crc >> 1U) ^ poly;
41 } else {
42 crc = crc >> 1U;
43 }
44 }
45 }
46
47
48 return crc;
49 }
50
51
crc16_ccitt(uint16_t seed,const uint8_t * src,size_t len)52 uint16_t crc16_ccitt(uint16_t seed, const uint8_t *src, size_t len)
53 {
54 for (; len > 0; len--) {
55 uint8_t e, f;
56
57 e = seed ^ *src;
58 ++src;
59 f = e ^ (e << 4);
60 seed = (seed >> 8) ^ ((uint16_t)f << 8) ^ ((uint16_t)f << 3) ^ ((uint16_t)f >> 4);
61 }
62
63 return seed;
64 }
65
crc16_itu_t(uint16_t seed,const uint8_t * src,size_t len)66 uint16_t crc16_itu_t(uint16_t seed, const uint8_t *src, size_t len)
67 {
68 for (; len > 0; len--) {
69 seed = (seed >> 8U) | (seed << 8U);
70 seed ^= *src;
71 ++src;
72 seed ^= (seed & 0xffU) >> 4U;
73 seed ^= seed << 12U;
74 seed ^= (seed & 0xffU) << 5U;
75 }
76
77 return seed;
78 }
79
