def data_type(bit_width, prefix="uint", postfix="_t"):
    """Return a datatype based on a target bit width."""
    size = 64
    if bit_width <= 8:
        size = 8
    elif bit_width <= 16:
        size = 16
    elif bit_width <= 32:
        size = 32
    return "{}{}{}".format(prefix, size, postfix)