Analyze air conditioner checksum by reversing bytes and summing nibbles.

ac2.py

import re

data="""\
10100001 10010011 01100011  => 01110111
10100001 10010011 01100100  => 01110001
10100001 10010011 01100101  => 01110000
10100001 10010011 01100110  => 01110010
10100001 10010011 01100111  => 01110011
10100001 10010011 01101000  => 01111001
10100001 10010011 01101001  => 01111000
10100001 10010011 01101010  => 01111010
10100001 10010011 01101011  => 01111011
10100001 10010011 01101100  => 01111110
10100001 10010011 01101101  => 01111111
10100001 10010011 01101110  => 01111100
10100001 10010011 01101111  => 01111101
10100001 10010011 01110001  => 01100100
10100001 10010011 01110010  => 01100110
10100001 10010011 01110011  => 01100111
10100001 10010011 01110100  => 01100001
10100001 10010011 01110101  => 01100000
10100001 10010011 01110111  => 01100011
10100001 10010011 01110111  => 01100011
10100001 10010011 01111000  => 01101001
10100001 10010011 01101000  => 01111001
10100001 00010011 01101000  => 11111001
10100001 00010011 01101100  => 11111110
10100001 10010011 01101100  => 01111110
10100001 10010100 01111110  => 01101011
10100001 10000010 01101100  => 01100000
10100001 10000001 01101100  => 01100011
10100001 10010011 01101100  => 01111110
10100001 10010000 01101100  => 01111100
10100001 10011000 01101100  => 01110100
10100001 10001000 01101100  => 01101100
10100001 10010000 01101100  => 01111100
10100001 10011000 01101100  => 01110100
10100010 00000010 11111111  => 01111110"""

data = [x.split('=>') for x in data.replace(' ', '').split('\n')]
data = [(a[::-1], b[::-1]) for a, b in data]

def hamming(a, b):
  c = 0
  for i in range(0, len(a)):
    if a[i] != b[i]:
       c += 1
  return c

def xor(a, b):
  return ''.join(['0' if x[0] == x[1] else '1' for x in zip(a, b)])

for i in range(0, len(data)):
  # Convert left nibbles to integers
  l = [int(x, 2) for x in re.findall('....', data[i][0])]
  # Convert right nibbles to integers
  r = [int(x, 2) for x in re.findall('....', data[i][1])]
  s1 = l[0]+l[2]+l[4]
  print data[i][0], s1, r[0], '*' if (-s1-2) & 0xf != r[0] else ''