fix 'hf iclass replay' (#888)
[proxmark3-svn] / common / iso15693tools.c
CommitLineData
9455b51c 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
be09ea86 10#include "iso15693tools.h"
11
cd028159 12#include <stddef.h>
9455b51c 13#include <stdint.h>
61aaee35 14#ifdef ON_DEVICE
15#include "printf.h"
16#else
17#include <stdio.h>
18#endif
19
9455b51c 20
be09ea86 21#define ISO15693_CRC_PRESET (uint16_t)0xFFFF
22#define ISO15693_CRC_POLY (uint16_t)0x8408
c3963755 23
24
9455b51c 25// The CRC as described in ISO 15693-Part 3-Annex C
be09ea86 26// v buffer with data
27// n length
28// returns crc as 16bit value
29uint16_t Iso15693Crc(uint8_t *v, int n) {
9455b51c 30 uint32_t reg;
31 int i, j;
32
be09ea86 33 reg = ISO15693_CRC_PRESET;
34 for (i = 0; i < n; i++) {
9455b51c 35 reg = reg ^ ((uint32_t)v[i]);
36 for (j = 0; j < 8; j++) {
37 if (reg & 0x0001) {
be09ea86 38 reg = (reg >> 1) ^ ISO15693_CRC_POLY;
9455b51c 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
be09ea86 49// req[] iso15963 frame without crc
50// n length without crc
9455b51c 51// returns the new length of the dataframe.
52int Iso15693AddCrc(uint8_t *req, int n) {
be09ea86 53 uint16_t crc = Iso15693Crc(req, n);
9455b51c 54 req[n] = crc & 0xff;
55 req[n+1] = crc >> 8;
be09ea86 56 return n + 2;
9455b51c 57}
58
3851172d 59
9455b51c 60// returns a string representation of the UID
61// UID is transmitted and stored LSB first, displayed MSB first
be09ea86 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
65char* 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", uid[7], uid[6], uid[5], uid[4], uid[3], uid[2], uid[1], uid[0]);
69 return target;
9455b51c 70}
71
be09ea86 72
28ae37b7 73uint16_t iclass_crc16(uint8_t *data_p, unsigned short length) {
be09ea86 74 unsigned char i;
75 unsigned int data;
76 uint16_t crc = ISO15693_CRC_PRESET;
77
78 if (length == 0)
79 return (~crc);
80
81 do {
28ae37b7 82 for (i = 0, data = 0xff & *data_p++; i < 8; i++, data >>= 1) {
be09ea86 83 if ((crc & 0x0001) ^ (data & 0x0001))
84 crc = (crc >> 1) ^ ISO15693_CRC_POLY;
85 else crc >>= 1;
86 }
87 } while (--length);
88
89 crc = ~crc;
90 data = crc;
91 crc = (crc << 8) | (data >> 8 & 0xff);
cd028159 92 crc = crc ^ 0x0BC3;
be09ea86 93 return (crc);
c3963755 94}
9455b51c 95
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