bd20f8f4 |
1 | //----------------------------------------------------------------------------- |
2 | // This code is licensed to you under the terms of the GNU GPL, version 2 or, |
3 | // at your option, any later version. See the LICENSE.txt file for the text of |
4 | // the license. |
5 | //----------------------------------------------------------------------------- |
6 | // Generic CRC calculation code. |
7 | //----------------------------------------------------------------------------- |
68d9d60a |
8 | #include "crc.h" |
73d04bb4 |
9 | #include <stdint.h> |
10 | #include <stddef.h> |
68d9d60a |
11 | |
12 | void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor) |
13 | { |
14 | crc->order = order; |
15 | crc->polynom = polynom; |
16 | crc->initial_value = initial_value; |
17 | crc->final_xor = final_xor; |
18 | crc->mask = (1L<<order)-1; |
19 | crc_clear(crc); |
20 | } |
21 | |
22 | void crc_update(crc_t *crc, uint32_t data, int data_width) |
23 | { |
24 | int i; |
25 | for(i=0; i<data_width; i++) { |
26 | int oldstate = crc->state; |
27 | crc->state = crc->state >> 1; |
28 | if( (oldstate^data) & 1 ) { |
29 | crc->state ^= crc->polynom; |
30 | } |
31 | data >>= 1; |
32 | } |
33 | } |
34 | |
35 | void crc_clear(crc_t *crc) |
36 | { |
37 | crc->state = crc->initial_value & crc->mask; |
38 | } |
39 | |
40 | uint32_t crc_finish(crc_t *crc) |
41 | { |
42 | return ( crc->state ^ crc->final_xor ) & crc->mask; |
43 | } |
73d04bb4 |
44 | |
e74fc2ec |
45 | //credits to iceman |
46 | uint32_t CRC8Maxim(uint8_t *buff, size_t size) |
73d04bb4 |
47 | { |
48 | crc_t crc; |
49 | crc_init(&crc, 9, 0x8c, 0x00, 0x00); |
50 | crc_clear(&crc); |
51 | |
52 | for (size_t i=0; i < size; ++i){ |
53 | crc_update(&crc, buff[i], 8); |
54 | } |
55 | return crc_finish(&crc); |
56 | } |