Method getfield

scapy/layers/can.py:331–366

(self, pkt, s)

        return tmp_s[:len(s)]

    def getfield(self, pkt, s):
        # type: (Packet, bytes) -> Tuple[bytes, Union[int, float]]
        if not isinstance(pkt, SignalPacket):
            raise Scapy_Exception("Only use SignalFields in a SignalPacket")

        if isinstance(s, tuple):
            s, _ = s

        if self._is_little_endian():
            msb_pos = self.start + self.size - 1
            lsb_pos = self.start
            shift = self.start
            fmt = "<Q"
        else:
            msb_pos = self.start
            lsb_pos = self._lsb_lookup(self.start, self.size)
            shift = (64 - self._msb_lookup(self.start) - self.size)
            fmt = ">Q"

        field_len = max(msb_pos, lsb_pos) // 8 + 1

        if pkt.wirelen is None:
            pkt.wirelen = field_len

        pkt.wirelen = max(pkt.wirelen, field_len)

        fld_val = struct.unpack(fmt, (s + b"\x00" * 8)[:8])[0] >> shift
        fld_val &= ((1 << self.size) - 1)

        if self._is_float_number():
            fld_val = struct.unpack(self.fmt,
                                    struct.pack(self.fmt[0] + "I", fld_val))[0]
        elif self._is_signed_number():
            fld_val = self._convert_to_signed(fld_val, self.size)

        return s, self.m2i(pkt, fld_val)

    def randval(self):
        # type: () -> Union[RandBinFloat, RandFloat]