f121445862ceccf8c5d048cd41b2960840521d2f
[proxmark3-svn] / common / iso15693tools.c
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 // ISO15693 CRC & other commons
7 //-----------------------------------------------------------------------------
8
9
10 #include "proxmark3.h"
11 #include <stdint.h>
12 #include <stdlib.h>
13 //#include "iso15693tools.h"
14 #ifdef ON_DEVICE
15 #include "printf.h"
16 #else
17 #include <stdio.h>
18 #endif
19
20
21 #define POLY 0x8408
22
23
24 // The CRC as described in ISO 15693-Part 3-Annex C
25 // v buffer with data
26 // n length
27 // returns crc as 16bit value
28 uint16_t Iso15693Crc(uint8_t *v, int n)
29 {
30 uint32_t reg;
31 int i, j;
32
33 reg = 0xffff;
34 for(i = 0; i < n; i++) {
35 reg = reg ^ ((uint32_t)v[i]);
36 for (j = 0; j < 8; j++) {
37 if (reg & 0x0001) {
38 reg = (reg >> 1) ^ 0x8408;
39 } else {
40 reg = (reg >> 1);
41 }
42 }
43 }
44
45 return ~(uint16_t)(reg & 0xffff);
46 }
47
48 // adds a CRC to a dataframe
49 // req[] iso15963 frame without crc
50 // n length without crc
51 // returns the new length of the dataframe.
52 int Iso15693AddCrc(uint8_t *req, int n) {
53 uint16_t crc=Iso15693Crc(req,n);
54 req[n] = crc & 0xff;
55 req[n+1] = crc >> 8;
56 return n+2;
57 }
58
59
60 // returns a string representation of the UID
61 // UID is transmitted and stored LSB first, displayed MSB first
62 // target char* buffer, where to put the UID, if NULL a static buffer is returned
63 // uid[] the UID in transmission order
64 // return: ptr to string
65 char* Iso15693sprintUID(char *target,uint8_t *uid) {
66 static char tempbuf[2*8+1]="";
67 if (target==NULL) target=tempbuf;
68 sprintf(target,"%02X%02X%02X%02X%02X%02X%02X%02X",
69 uid[7],uid[6],uid[5],uid[4],uid[3],uid[2],uid[1],uid[0]);
70 return target;
71 }
72
73 uint16_t iclass_crc16(char *data_p, unsigned short length)
74 {
75 unsigned char i;
76 unsigned int data;
77 uint16_t crc = 0xffff;
78
79 if (length == 0)
80 return (~crc);
81
82 do
83 {
84 for (i=0, data=(unsigned int)0xff & *data_p++;
85 i < 8;
86 i++, data >>= 1)
87 {
88 if ((crc & 0x0001) ^ (data & 0x0001))
89 crc = (crc >> 1) ^ POLY;
90 else crc >>= 1;
91 }
92 } while (--length);
93
94 crc = ~crc;
95 data = crc;
96 crc = (crc << 8) | (data >> 8 & 0xff);
97 crc = crc ^ 0xBC3;
98 return (crc);
99 }
100
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