Moving code around to help my understanding. file names most probably wrong right now but will update when understand it better

parity.py

@@ -0,0 +1,49 @@
+'''
+   Copyright 2015 Wolfgang Nagele
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+'''
+def bin2dec(buf):
+  if 0 == len(buf): # Crap input
+    return -1
+  return int(buf, 2)
+
+# Ported from: http://www.radarspotters.eu/forum/index.php?topic=5617.msg41293#msg41293
+def get_parity(msg, extended):
+  msg_length = len(msg)
+  payload = msg[:msg_length - 24]
+  parity = msg[msg_length - 24:]
+
+  data = bin2dec(payload[0:32])
+  if extended:
+    data1 = bin2dec(payload[32:64])
+    data2 = bin2dec(payload[64:]) << 8
+
+  hex_id = bin2dec(parity) << 8
+
+  for i in range(0, len(payload)):
+    if ((data & 0x80000000) != 0):
+      data ^= 0xFFFA0480
+    data <<= 1
+
+    if extended:
+      if ((data1 & 0x80000000) != 0):
+        data |= 1
+      data1 <<= 1
+
+      if ((data2 & 0x80000000) != 0):
+        data1 = data1 | 1
+      data2 <<= 1
+
+  return data
+  #return (data ^ hex_id) >> 8