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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) {
32 crc->state = crc->initial_value & crc->mask;
33 if (crc->refin)
34 crc->state = reflect(crc->state, crc->order);
35}
36
37void crc_update(crc_t *crc, uint32_t indata, int data_width){
38
39 //reflected
40 if (crc->refin) indata = reflect(indata, data_width);
41
42 // Bring the next byte into the remainder.
43 crc->state ^= indata << (crc->order - data_width);
44
45 for( uint8_t bit = data_width; bit > 0; --bit) {
22f4dca8 46
47
3e134b4c 48 // Try to divide the current data bit.
49 if (crc->state & crc->topbit)
50 crc->state = (crc->state << 1) ^ crc->polynom;
51 else
52 crc->state = (crc->state << 1);
68d9d60a 53 }
54}
55
22f4dca8 56void crc_update2(crc_t *crc, uint32_t data, int data_width)
57{
58 if (crc->refin) data = reflect(data, data_width);
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
71
3e134b4c 72uint32_t crc_finish(crc_t *crc) {
73 uint32_t val = crc->state;
74 if (crc->refout) val = reflect(val, crc->order);
75 return ( val ^ crc->final_xor ) & crc->mask;
68d9d60a 76}
77
3e134b4c 78/*
79static void print_crc(crc_t *crc) {
80 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",
81 crc->order,
82 crc->polynom,
83 crc->initial_value,
84 crc->final_xor,
85 crc->mask,
86 crc->topbit,
87 (crc->refin) ? "TRUE":"FALSE",
88 (crc->refout) ? "TRUE":"FALSE",
89 crc->state
90 );
68d9d60a 91}
3e134b4c 92*/
73d04bb4 93
3e134b4c 94// width=8 poly=0x31 init=0x00 refin=true refout=true xorout=0x00 check=0xA1 name="CRC-8/MAXIM"
6bb7609c 95uint32_t CRC8Maxim(uint8_t *buff, size_t size) {
73d04bb4 96 crc_t crc;
3e134b4c 97 crc_init_ref(&crc, 8, 0x31, 0, 0, TRUE, TRUE);
98 for ( int i=0; i < size; ++i)
99 crc_update(&crc, buff[i], 8);
100 return crc_finish(&crc);
101}
102
3e134b4c 103// width=4 poly=0xC, reversed poly=0x7 init=0x5 refin=true refout=true xorout=0x0000 check= name="CRC-4/LEGIC"
22f4dca8 104uint32_t CRC4Legic(uint8_t *cmd, size_t size) {
105 crc_t crc;
106 crc_init_ref(&crc, 4, 0x19 >> 1, 0x5, 0, TRUE, TRUE);
107 crc_update2(&crc, 1, 1); /* CMD_READ */
108 crc_update2(&crc, cmd[0], 8);
109 crc_update2(&crc, cmd[1], 8);
110 return reflect(crc_finish(&crc), 4);
111}
3e134b4c 112// width=8 poly=0x63, reversed poly=0x8D init=0x55 refin=true refout=true xorout=0x0000 check=0xC6 name="CRC-8/LEGIC"
113// the CRC needs to be reversed before returned.
114uint32_t CRC8Legic(uint8_t *buff, size_t size) {
115 crc_t crc;
116 crc_init_ref(&crc, 8, 0x63, 0x55, 0, TRUE, TRUE);
117 for ( int i = 0; i < size; ++i)
73d04bb4 118 crc_update(&crc, buff[i], 8);
3e134b4c 119 return reflect(crc_finish(&crc), 8);
120}
ee4e2816 121
3e134b4c 122// This CRC-16 is used in Legic Advant systems.
123// width=8 poly=0xB400, reversed poly=0x init=depends refin=true refout=true xorout=0x0000 check= name="CRC-16/LEGIC"
124uint32_t CRC16Legic(uint8_t *buff, size_t size, uint8_t uidcrc) {
ee4e2816 125
3e134b4c 126 #define CRC16_POLY_LEGIC 0xB400
514ddaa2 127 uint16_t initial = reflect(uidcrc, 8);
128 //uint16_t initial = uidcrc;
3e134b4c 129 initial |= initial << 8;
ee4e2816 130 crc_t crc;
3e134b4c 131 crc_init_ref(&crc, 16, CRC16_POLY_LEGIC, initial, 0, TRUE, TRUE);
132 for ( int i=0; i < size; ++i)
ee4e2816 133 crc_update(&crc, buff[i], 8);
3e134b4c 134 return reflect(crc_finish(&crc), 16);
ee4e2816 135}
136
3e134b4c 137//w=16 poly=0x3d65 init=0x0000 refin=true refout=true xorout=0xffff check=0xea82 name="CRC-16/DNP"
138uint32_t CRC16_DNP(uint8_t *buff, size_t size) {
139 crc_t crc;
140 crc_init_ref(&crc, 16, 0x3d65, 0, 0xffff, TRUE, TRUE);
141 for ( int i=0; i < size; ++i)
142 crc_update(&crc, buff[i], 8);
143
144 return BSWAP_16(crc_finish(&crc));
145}
6bb7609c 146
3e134b4c 147//width=16 poly=0x1021 init=0x1d0f refin=false refout=false xorout=0x0000 check=0xe5cc name="CRC-16/AUG-CCITT"
148uint32_t CRC16_CCITT(uint8_t *buff, size_t size) {
149 crc_t crc;
150 crc_init(&crc, 16, 0x1021, 0x1d0f, 0);
151 for ( int i=0; i < size; ++i)
152 crc_update(&crc, buff[i], 8);
153 return crc_finish(&crc);
82e690f4 154}
155//width=16 poly=0x8408 init=0xffff refin=false refout=true xorout=0xffff check=0xF0B8 name="CRC-16/ISO/IEC 13239"
156uint32_t CRC16_Iso15693(uint8_t *buff, size_t size) {
157 crc_t crc;
158 crc_init_ref(&crc, 16, 0x8408, 0xFFFF, 0xFFFF, true, false);
159 for ( int i=0; i < size; ++i)
160 crc_update(&crc, buff[i], 8);
161 return reflect(crc_finish(&crc), 16);
162}
163//width=16 poly=0x8408 init=0xffff refin=true refout=true xorout=0x0BC3 check=0xF0B8 name="CRC-16/ICLASS"
164uint32_t CRC16_ICLASS(uint8_t *buff, size_t size) {
165
166 crc_t crc;
167 crc_init_ref(&crc, 16, 0x8408, 0xFFFF, 0x0BC3, false, false);
168 for ( int i=0; i < size; ++i)
169 crc_update(&crc, buff[i], 8);
170 return crc_finish(&crc);
3e134b4c 171}
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