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Commit | Line | Data |
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4962d414 | 1 | #!/usr/bin/python |
2 | ||
98af9ddf | 3 | # xorcheck.py - find xor values for 8-bit LRC |
4962d414 | 4 | # |
5 | # Adam Laurie <adam@algroup.co.uk> | |
6 | # http://rfidiot.org/ | |
7 | # | |
8 | # This code is copyright (c) Adam Laurie, 2009, All rights reserved. | |
9 | # For non-commercial use only, the following terms apply - for all other | |
10 | # uses, please contact the author: | |
11 | # | |
12 | # This code is free software; you can redistribute it and/or modify | |
13 | # it under the terms of the GNU General Public License as published by | |
14 | # the Free Software Foundation; either version 2 of the License, or | |
15 | # (at your option) any later version. | |
16 | # | |
17 | # This code is distributed in the hope that it will be useful, | |
18 | # but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | # GNU General Public License for more details. | |
21 | # | |
22 | ||
23 | import sys | |
24 | import os | |
25 | ||
26 | if(len(sys.argv) < 3): | |
27 | ||
98af9ddf | 28 | print '\t'+sys.argv[0] + ' - Generate final byte for XOR LRC' |
c5847014 | 29 | |
98af9ddf | 30 | print 'Usage: ' + sys.argv[0] + ' <ID Byte1> <ID Byte2> ... <LRC>' |
4962d414 | 31 | |
98af9ddf | 32 | print '\tSpecifying the bytes of a UID with a known LRC will find the last byte value' |
33 | print '\tneeded to generate that LRC with a rolling XOR. All bytes should be specified in HEX.' | |
4962d414 | 34 | |
35 | print 'Example:' | |
36 | ||
37 | print '\txorcheck.py 04 00 80 64 ba' | |
38 | ||
39 | print 'Should produce the output:' | |
40 | ||
7cea81ee | 41 | print '\tTarget (BA) requires final LRC XOR byte value: 5A' |
4962d414 | 42 | |
43 | os._exit(True) | |
44 | ||
45 | target= int(sys.argv[len(sys.argv) - 1],16) | |
46 | ||
98af9ddf | 47 | lrc= 0x00 |
48 | for i in range(len(sys.argv) - 1): | |
49 | lrc ^= int(sys.argv[i + 1],16) | |
50 | ||
51 | print 'Target (%02X) requires final LRC XOR byte value: %02X' % (target,lrc) | |
52 |