optimize error checking

errors.py

@@ -1,20 +1,22 @@
 #!/usr/bin/env python
-import common
+import bitarray
 import sys
 
-tx, rx = sys.argv[1:]
-tx = bytearray(open(tx).read())
-rx = bytearray(open(rx).read())
+tx_fname, rx_fname = sys.argv[1:]
+tx = bitarray.bitarray()
+tx.fromfile(open(tx_fname))
+
+rx = bitarray.bitarray()
+rx.fromfile(open(rx_fname))
 
 L = min(len(tx), len(rx))
 if L == 0:
     sys.exit(1)
 
-rx = list(common.to_bits(rx[:L]))
-tx = list(common.to_bits(tx[:L]))
-indices = [index for index, (r, t) in enumerate(zip(rx, tx)) if r != t]
-
-total = L*8
-errors = len(indices)
-print('{}/{} bit error rate: {:.3f}%'.format(errors, total, (100.0 * errors) / total))
+rx = rx[:L]
+tx = tx[:L]
+errors = (rx ^ tx).count(1)
+total = L
+ber = float(errors) / total  # bit error rate
+print('BER: {:.3f}% ({}/{})'.format(100 * ber, errors, total))
 sys.exit(int(errors > 0))