Class FixedPointField

scapy/fields.py:3377–3406

class FixedPointField(BitField):
    __slots__ = ['frac_bits']

    def __init__(self, name, default, size, frac_bits=16):
        # type: (str, int, int, int) -> None
        self.frac_bits = frac_bits
        super(FixedPointField, self).__init__(name, default, size)

    def any2i(self, pkt, val):
        # type: (Optional[Packet], Optional[float]) -> Optional[int]
        if val is None:
            return val
        ival = int(val)
        fract = int((val - ival) * 2**self.frac_bits)
        return (ival << self.frac_bits) | fract

    def i2h(self, pkt, val):
        # type: (Optional[Packet], Optional[int]) -> Optional[EDecimal]
        # A bit of trickery to get precise floats
        if val is None:
            return val
        int_part = val >> self.frac_bits
        pw = 2.0**self.frac_bits
        frac_part = EDecimal(val & (1 << self.frac_bits) - 1)
        frac_part /= pw  # type: ignore
        return int_part + frac_part.normalize(int(math.log10(pw)))

    def i2repr(self, pkt, val):
        # type: (Optional[Packet], int) -> str
        return str(self.i2h(pkt, val))


# Base class for IPv4 and IPv6 Prefixes inspired by IPField and IP6Field.