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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//-----------------------------------------------------------------------------
8
9#ifndef __CRC_H
10#define __CRC_H
11
12#include <stdint.h> //uint32+
13#include <stdbool.h> //bool
14#include <stddef.h>
15#include "util.h" // reflect, bswap_16
16
17typedef struct crc {
18 uint32_t state;
19 int order;
20 uint32_t polynom;
21 uint32_t initial_value;
22 uint32_t final_xor;
23 uint32_t mask;
24 int topbit;
25 bool refin; /* Parameter: Reflect input bytes? */
26 bool refout; /* Parameter: Reflect output CRC? */
27} crc_t;
28
29/* Initialize a crc structure. order is the order of the polynom, e.g. 32 for a CRC-32
30 * polynom is the CRC polynom. initial_value is the initial value of a clean state.
31 * final_xor is XORed onto the state before returning it from crc_result().
32 * refin is the setting for reversing (bitwise) the bytes during crc
33 * refot is the setting for reversing (bitwise) the crc byte before returning it.
34 */
35extern void crc_init_ref(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor, bool refin, bool refout);
36
37/* Initialize a crc structure. order is the order of the polynom, e.g. 32 for a CRC-32
38 * polynom is the CRC polynom. initial_value is the initial value of a clean state.
39 * final_xor is XORed onto the state before returning it from crc_result(). */
40extern void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor);
41
42
43/* Update the crc state. data is the data of length data_width bits (only the
44 * data_width lower-most bits are used).
45 */
46extern void crc_update(crc_t *crc, uint32_t data, int data_width);
47extern void crc_update2(crc_t *crc, uint32_t data, int data_width);
48
49/* Clean the crc state, e.g. reset it to initial_value */
50extern void crc_clear(crc_t *crc);
51
52/* Get the result of the crc calculation */
53extern uint32_t crc_finish(crc_t *crc);
54
55// Calculate CRC-8/Maxim checksum
56uint32_t CRC8Maxim(uint8_t *buff, size_t size);
57
58// Calculate CRC-4/Legic checksum
59uint32_t CRC4Legic(uint8_t *buff, size_t size);
60
61// Calculate CRC-8/Legic checksum
62uint32_t CRC8Legic(uint8_t *buff, size_t size);
63
64// Calculate CRC-16/Legic checksum
65// the initial_value is based on the previous legic_Crc8 of the UID.
66// ie: uidcrc = 0x78 then initial_value == 0x7878
67uint32_t CRC16Legic(uint8_t *buff, size_t size, uint8_t uidcrc);
68
69// test crc 16.
70uint32_t CRC16_DNP(uint8_t *buff, size_t size);
71uint32_t CRC16_CCITT(uint8_t *buff, size_t size);
72uint32_t CRC16_Iso15693(uint8_t *buff, size_t size);
73uint32_t CRC16_ICLASS(uint8_t *buff, size_t size);
74
75/* Static initialization of a crc structure */
76#define CRC_INITIALIZER(_order, _polynom, _initial_value, _final_xor) { \
77 .state = ((_initial_value) & ((1L<<(_order))-1)), \
78 .order = (_order), \
79 .polynom = (_polynom), \
80 .initial_value = (_initial_value), \
81 .final_xor = (_final_xor), \
82 .mask = ((1L<<(_order))-1) \
83 .refin = FALSE, \
84 .refout = FALSE \
85 }
86
87#endif /* __CRC_H */
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