special handling for the px4 style of PARAM_VALUE

def handle_px4_param_value(self, m):
        '''special handling for the px4 style of PARAM_VALUE'''
        if m.param_type == mavutil.mavlink.MAV_PARAM_TYPE_REAL32:
            # already right type
            return m.param_value
        is_px4_params = False
        if m.get_srcComponent() in [mavutil.mavlink.MAV_COMP_ID_UDP_BRIDGE]:
            # ESP8266 uses PX4 style parameters
            is_px4_params = True
        sysid = m.get_srcSystem()
        if self.autopilot_type_by_sysid.get(sysid,-1) in [mavutil.mavlink.MAV_AUTOPILOT_PX4]:
            is_px4_params = True
        if not is_px4_params:
            return m.param_value
        # try to extract px4 param value
        value = m.param_value
        try:
            v = struct.pack(">f", value)
        except Exception:
            return value
        if m.param_type == mavutil.mavlink.MAV_PARAM_TYPE_UINT8:
            value, = struct.unpack(">B", v[3:])
        elif m.param_type == mavutil.mavlink.MAV_PARAM_TYPE_INT8:
            value, = struct.unpack(">b", v[3:])
        elif m.param_type == mavutil.mavlink.MAV_PARAM_TYPE_UINT16:
            value, = struct.unpack(">H", v[2:])
        elif m.param_type == mavutil.mavlink.MAV_PARAM_TYPE_INT16:
            value, = struct.unpack(">h", v[2:])
        elif m.param_type == mavutil.mavlink.MAV_PARAM_TYPE_UINT32:
            value, = struct.unpack(">I", v[0:])
        elif m.param_type == mavutil.mavlink.MAV_PARAM_TYPE_INT32:
            value, = struct.unpack(">i", v[0:])
        # can't pack other types

        # remember type for param set
        self.param_types[m.param_id.upper()] = m.param_type
        return value