class Register:
    registers = []

    def __init__(self, n_bits, name=None):
        self.n_bits = n_bits
        if name is None:
            self.name = "r{}".format(len(Register.registers))
        else:
            self.name = name
        self.value = 0
        Register.registers.append(self)

    def truncate(self, value, bits=None):
        if bits is None:
            bits = self.n_bits
        return value & (1 << bits - 1)

    def set(self, value):
        if value < 0:
            self.value = self.truncate(abs(value), self.n_bits - 1)
            self.negate()
        self.value = self.truncate(value)

    def get(self):
        return self.value

    def negate(self):
        self.value = ~self.value + 1


class Acumulator(Register):
    positive_flag = False
    negative_flag = False
    zero_flag = False
    carry = False

    def add(self, register):
        pass