fix wrong terminology - LRC/CRC and calulate result instead of matching (thanks Henryk!)

diff --git a/tools/xorcheck.py b/tools/xorcheck.py
index 9cbc7a1e7ade0f203a415eae635c8e4ed6c7830e..37aa27ce4b4fd23609b960f6481a302a32d18ff6 100755 (executable)
--- a/tools/xorcheck.py
+++ b/tools/xorcheck.py
@@ -1,6 +1,6 @@
 #!/usr/bin/python
 
 #!/usr/bin/python
 

-#  xorcheck.py - find xor values for 8-bit CRC
+#  xorcheck.py - find xor values for 8-bit LRC

 # 
 #  Adam Laurie <adam@algroup.co.uk>
 #  http://rfidiot.org/
 # 
 #  Adam Laurie <adam@algroup.co.uk>
 #  http://rfidiot.org/


@@ -25,12 +25,12 @@ import os
 
 if(len(sys.argv) < 3):
        print
 
 if(len(sys.argv) < 3):
        print

-       print '\t'+sys.argv[0] + ' - Generate final byte for XOR CRC'
+       print '\t'+sys.argv[0] + ' - Generate final byte for XOR LRC'

        print
        print

-       print 'Usage: ' + sys.argv[0] + ' <ID Byte1> <ID Byte2> ... <CRC>'
+       print 'Usage: ' + sys.argv[0] + ' <ID Byte1> <ID Byte2> ... <LRC>'

        print
        print

-       print '\tSpecifying the bytes of a UID with a known CRC will find the last byte value'
-       print '\tneeded to generate that CRC with a rolling XOR. All bytes should be specified in HEX.'
+       print '\tSpecifying the bytes of a UID with a known LRC will find the last byte value'
+       print '\tneeded to generate that LRC with a rolling XOR. All bytes should be specified in HEX.'

        print
        print 'Example:'
        print
        print
        print 'Example:'
        print


@@ -38,19 +38,15 @@ if(len(sys.argv) < 3):
        print
        print 'Should produce the output:'
        print
        print
        print 'Should produce the output:'
        print

-       print '\tTarget (BA) matched with final byte value: 5A'
+       print '\tTarget (BA) matched with final LRC XOR byte value: 5A'

        print
        os._exit(True)
 
 target= int(sys.argv[len(sys.argv) - 1],16)
 
        print
        os._exit(True)
 
 target= int(sys.argv[len(sys.argv) - 1],16)
 

-for candidate in range(256):
-       crc= 0x00
-       for i in range(len(sys.argv) - 2):
-               crc ^= int(sys.argv[i + 1],16)
-       crc ^= candidate
-       if (crc == target):
-               print
-               print 'Target (%02X) matched with final byte value: %02X' % (target,candidate)
-               print
-
+lrc= 0x00
+for i in range(len(sys.argv) - 1):
+       lrc ^= int(sys.argv[i + 1],16)
+print
+print 'Target (%02X) requires final LRC XOR byte value: %02X' % (target,lrc)
+print