def to_words()

in otp.py [0:0]

• 7 lines of code
• 4 McCabe index (conditional complexity)

def to_words(value):
  "Convert a 64-bit value into words, with a parity value."
  assert len(value) == 8  # 64 bits, in an 8-byte VALUE

  # Parity is the summation of each 2-bit pair. We will mask
  # out the lowest 2 bits, so no worries about higher bits.
  parity = sum((b >> 6) + (b >> 4) + (b >> 2) + b for b in value)

  # collapse the bytes into a single 64-bit integer; fold in parity bits
  i64 = int.from_bytes(value, byteorder='big')
  i64 = (i64 << 2) | (parity & 0x03)
  
  # and map that integer into words, using the spec's WORDS
  return [WORDS[(i64 >> (i*11)) & 0x7FF] for i in (5, 4, 3, 2, 1, 0)]