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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//-----------------------------------------------------------------------------
3e134b4c 8// the Check value below in the comments is CRC of the string '123456789'
9//
68d9d60a 10#include "crc.h"
11
3e134b4c 12void crc_init_ref(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor, bool refin, bool refout) {
13 crc_init(crc, order, polynom, initial_value, final_xor);
14 crc->refin = refin;
15 crc->refout = refout;
16 crc_clear(crc);
17}
18
19void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor) {
68d9d60a 20 crc->order = order;
3e134b4c 21 crc->topbit = BITMASK( order-1 );
68d9d60a 22 crc->polynom = polynom;
23 crc->initial_value = initial_value;
24 crc->final_xor = final_xor;
25 crc->mask = (1L<<order)-1;
3e134b4c 26 crc->refin = FALSE;
27 crc->refout = FALSE;
68d9d60a 28 crc_clear(crc);
29}
30
3e134b4c 31void crc_clear(crc_t *crc) {
a3994421 32
3e134b4c 33 crc->state = crc->initial_value & crc->mask;
34 if (crc->refin)
35 crc->state = reflect(crc->state, crc->order);
36}
37
cb7902cd 38void crc_update2(crc_t *crc, uint32_t data, int data_width){
b7e8338d 39
a3994421 40 if (crc->refin)
b7e8338d 41 data = reflect(data, data_width);
3e134b4c 42
43 // Bring the next byte into the remainder.
b7e8338d 44 crc->state ^= data << (crc->order - data_width);
3e134b4c 45
a3994421 46 for( uint8_t bit = data_width; bit > 0; --bit) {
b7e8338d 47
3e134b4c 48 if (crc->state & crc->topbit)
b7e8338d 49 crc->state = (crc->state << 1) ^ crc->polynom;
3e134b4c 50 else
51 crc->state = (crc->state << 1);
68d9d60a 52 }
53}
54
cb7902cd 55void crc_update(crc_t *crc, uint32_t data, int data_width)
22f4dca8 56{
a3994421 57 if (crc->refin)
58 data = reflect(data, data_width);
22f4dca8 59
60 int i;
61 for(i=0; i<data_width; i++) {
62 int oldstate = crc->state;
63 crc->state = crc->state >> 1;
64 if( (oldstate^data) & 1 ) {
65 crc->state ^= crc->polynom;
66 }
67 data >>= 1;
68 }
69}
70
3e134b4c 71uint32_t crc_finish(crc_t *crc) {
72 uint32_t val = crc->state;
73 if (crc->refout) val = reflect(val, crc->order);
74 return ( val ^ crc->final_xor ) & crc->mask;
68d9d60a 75}
76
3e134b4c 77/*
78static void print_crc(crc_t *crc) {
79 printf(" Order %d\n Poly %x\n Init %x\n Final %x\n Mask %x\n topbit %x\n RefIn %s\n RefOut %s\n State %x\n",
80 crc->order,
81 crc->polynom,
82 crc->initial_value,
83 crc->final_xor,
84 crc->mask,
85 crc->topbit,
86 (crc->refin) ? "TRUE":"FALSE",
87 (crc->refout) ? "TRUE":"FALSE",
88 crc->state
89 );
68d9d60a 90}
3e134b4c 91*/
73d04bb4 92
3e134b4c 93// width=8 poly=0x31 init=0x00 refin=true refout=true xorout=0x00 check=0xA1 name="CRC-8/MAXIM"
6bb7609c 94uint32_t CRC8Maxim(uint8_t *buff, size_t size) {
73d04bb4 95 crc_t crc;
3e134b4c 96 crc_init_ref(&crc, 8, 0x31, 0, 0, TRUE, TRUE);
97 for ( int i=0; i < size; ++i)
68043382 98 crc_update2(&crc, buff[i], 8);
3e134b4c 99 return crc_finish(&crc);
100}
101
3e134b4c 102// width=4 poly=0xC, reversed poly=0x7 init=0x5 refin=true refout=true xorout=0x0000 check= name="CRC-4/LEGIC"
22f4dca8 103uint32_t CRC4Legic(uint8_t *cmd, size_t size) {
104 crc_t crc;
105 crc_init_ref(&crc, 4, 0x19 >> 1, 0x5, 0, TRUE, TRUE);
106 crc_update2(&crc, 1, 1); /* CMD_READ */
107 crc_update2(&crc, cmd[0], 8);
108 crc_update2(&crc, cmd[1], 8);
109 return reflect(crc_finish(&crc), 4);
110}
3e134b4c 111// width=8 poly=0x63, reversed poly=0x8D init=0x55 refin=true refout=true xorout=0x0000 check=0xC6 name="CRC-8/LEGIC"
112// the CRC needs to be reversed before returned.
113uint32_t CRC8Legic(uint8_t *buff, size_t size) {
114 crc_t crc;
115 crc_init_ref(&crc, 8, 0x63, 0x55, 0, TRUE, TRUE);
116 for ( int i = 0; i < size; ++i)
77a689db 117 crc_update2(&crc, buff[i], 8);
3e134b4c 118 return reflect(crc_finish(&crc), 8);
119}
ee4e2816 120
3e134b4c 121// This CRC-16 is used in Legic Advant systems.
122// width=8 poly=0xB400, reversed poly=0x init=depends refin=true refout=true xorout=0x0000 check= name="CRC-16/LEGIC"
123uint32_t CRC16Legic(uint8_t *buff, size_t size, uint8_t uidcrc) {
ee4e2816 124
3e134b4c 125 #define CRC16_POLY_LEGIC 0xB400
514ddaa2 126 uint16_t initial = reflect(uidcrc, 8);
127 //uint16_t initial = uidcrc;
3e134b4c 128 initial |= initial << 8;
ee4e2816 129 crc_t crc;
3e134b4c 130 crc_init_ref(&crc, 16, CRC16_POLY_LEGIC, initial, 0, TRUE, TRUE);
131 for ( int i=0; i < size; ++i)
ee4e2816 132 crc_update(&crc, buff[i], 8);
3e134b4c 133 return reflect(crc_finish(&crc), 16);
ee4e2816 134}
135
3e134b4c 136//w=16 poly=0x3d65 init=0x0000 refin=true refout=true xorout=0xffff check=0xea82 name="CRC-16/DNP"
137uint32_t CRC16_DNP(uint8_t *buff, size_t size) {
138 crc_t crc;
139 crc_init_ref(&crc, 16, 0x3d65, 0, 0xffff, TRUE, TRUE);
140 for ( int i=0; i < size; ++i)
68043382 141 crc_update2(&crc, buff[i], 8);
3e134b4c 142
143 return BSWAP_16(crc_finish(&crc));
144}
6bb7609c 145
3e134b4c 146//width=16 poly=0x1021 init=0x1d0f refin=false refout=false xorout=0x0000 check=0xe5cc name="CRC-16/AUG-CCITT"
147uint32_t CRC16_CCITT(uint8_t *buff, size_t size) {
148 crc_t crc;
149 crc_init(&crc, 16, 0x1021, 0x1d0f, 0);
150 for ( int i=0; i < size; ++i)
151 crc_update(&crc, buff[i], 8);
152 return crc_finish(&crc);
82e690f4 153}
154//width=16 poly=0x8408 init=0xffff refin=false refout=true xorout=0xffff check=0xF0B8 name="CRC-16/ISO/IEC 13239"
155uint32_t CRC16_Iso15693(uint8_t *buff, size_t size) {
156 crc_t crc;
157 crc_init_ref(&crc, 16, 0x8408, 0xFFFF, 0xFFFF, true, false);
158 for ( int i=0; i < size; ++i)
159 crc_update(&crc, buff[i], 8);
160 return reflect(crc_finish(&crc), 16);
161}
162//width=16 poly=0x8408 init=0xffff refin=true refout=true xorout=0x0BC3 check=0xF0B8 name="CRC-16/ICLASS"
163uint32_t CRC16_ICLASS(uint8_t *buff, size_t size) {
164
165 crc_t crc;
166 crc_init_ref(&crc, 16, 0x8408, 0xFFFF, 0x0BC3, false, false);
167 for ( int i=0; i < size; ++i)
168 crc_update(&crc, buff[i], 8);
169 return crc_finish(&crc);
3e134b4c 170}
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