Initial commit

crc.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python
+#
+###############################################################################
+#   Copyright (C) 2016-2018  Cortney T. Buffington, N0MJS <n0mjs@me.com>
+#
+#   This program is free software; you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation; either version 3 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program; if not, write to the Free Software Foundation,
+#   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
+###############################################################################
+
+
+from bitarray import bitarray
+
+# Does anybody read this stuff? There's a PEP somewhere that says I should do this.
+__author__     = 'Cortney T. Buffington, N0MJS'
+__copyright__  = 'Copyright (c) 2016-2018 Cortney T. Buffington, N0MJS and the K0USY Group'
+__credits__    = 'Jonathan Naylor, G4KLX'
+__license__    = 'GNU GPLv3'
+__maintainer__ = 'Cort Buffington, N0MJS'
+__email__      = 'n0mjs@me.com'
+
+
+def csum5(_data):
+    accum = 0
+    assert len(_data) == 9, 'csum5 expected 9 bytes of data and got something else'
+    
+    for i in range(9):
+        accum += _data[i]
+    accum = bytes([accum % 31])
+    csum = bitarray()
+    csum.frombytes(accum)
+    del csum[0:3]
+
+    return csum
+
+
+if __name__ == '__main__':
+    
+    message = b'\x00\x10\x20\x00\x0c\x30\x2f\x9b\xe5'
+    
+    result = csum5(message)
+    print(result, type(result))