2da6c7f9f3e312cce39cdeacb95d1780c12157fa
[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 "iso15693tools.h"
11
12 #include "proxmark3.h"
13 #include <stdint.h>
14 #include <stdlib.h>
15 #ifdef ON_DEVICE
16 #include "printf.h"
17 #else
18 #include <stdio.h>
19 #endif
20
21
22 #define ISO15693_CRC_PRESET (uint16_t)0xFFFF
23 #define ISO15693_CRC_POLY (uint16_t)0x8408
24
25
26 // The CRC as described in ISO 15693-Part 3-Annex C
27 // v buffer with data
28 // n length
29 // returns crc as 16bit value
30 uint16_t Iso15693Crc(uint8_t *v, int n) {
31 uint32_t reg;
32 int i, j;
33
34 reg = ISO15693_CRC_PRESET;
35 for (i = 0; i < n; i++) {
36 reg = reg ^ ((uint32_t)v[i]);
37 for (j = 0; j < 8; j++) {
38 if (reg & 0x0001) {
39 reg = (reg >> 1) ^ ISO15693_CRC_POLY;
40 } else {
41 reg = (reg >> 1);
42 }
43 }
44 }
45
46 return ~(uint16_t)(reg & 0xffff);
47 }
48
49 // adds a CRC to a dataframe
50 // req[] iso15963 frame without crc
51 // n length without crc
52 // returns the new length of the dataframe.
53 int Iso15693AddCrc(uint8_t *req, int n) {
54 uint16_t crc = Iso15693Crc(req, n);
55 req[n] = crc & 0xff;
56 req[n+1] = crc >> 8;
57 return n + 2;
58 }
59
60
61 // returns a string representation of the UID
62 // UID is transmitted and stored LSB first, displayed MSB first
63 // target char* buffer, where to put the UID, if NULL a static buffer is returned
64 // uid[] the UID in transmission order
65 // return: ptr to string
66 char* Iso15693sprintUID(char *target, uint8_t *uid) {
67 static char tempbuf[2*8+1] = "";
68 if (target == NULL) target = tempbuf;
69 sprintf(target, "%02X%02X%02X%02X%02X%02X%02X%02X", uid[7], uid[6], uid[5], uid[4], uid[3], uid[2], uid[1], uid[0]);
70 return target;
71 }
72
73
74 uint16_t iclass_crc16(char *data_p, unsigned short length) {
75 unsigned char i;
76 unsigned int data;
77 uint16_t crc = ISO15693_CRC_PRESET;
78
79 if (length == 0)
80 return (~crc);
81
82 do {
83 for (i = 0, data = (unsigned int)0xff & *data_p++; i < 8; i++, data >>= 1) {
84 if ((crc & 0x0001) ^ (data & 0x0001))
85 crc = (crc >> 1) ^ ISO15693_CRC_POLY;
86 else crc >>= 1;
87 }
88 } while (--length);
89
90 crc = ~crc;
91 data = crc;
92 crc = (crc << 8) | (data >> 8 & 0xff);
93 crc = crc ^ 0xBC3;
94 return (crc);
95 }
96
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