Ternary logic multiplication (0, 1, unknown)

gistfile1.txt

N_BITS = 8
MASK = (1 << N_BITS) - 1

class Ternary:
    def __init__(self, ones, unknowns):
        self.ones = ones & MASK
        self.unknowns = unknowns & MASK
    def __add__(self, other):
        x = self.ones + other.ones
        u = self.unknowns | other.unknowns | (x ^ (x + self.unknowns + other.unknowns))
        return Ternary(x & ~u, u)
    def __or__(self, other):
        o = self.ones | other.ones
        return Ternary(o, (self.unknowns | other.unknowns) & ~o)
    def __lshift__(self, count):
        return Ternary(self.ones << count, self.unknowns << count)
    def __mul__(self, other):
        result = Ternary(0, 0)
        for i in range(N_BITS):
            if self.ones & 1 << i:
                result += other << i
            elif self.unknowns & 1 << i:
                u = other << i
                result += Ternary(0, u.ones | u.unknowns)
        return result
    def __repr__(self):
        return ''.join('U' if self.unknowns & 1 << i else str(self.ones >> i & 1)
                for i in reversed(range(N_BITS)))