#!/usr/bin/env python3
# -*- coding: utf-8 -*-

# Copyright 2017 Daniel Estevez <daniel@destevez.net>
#
# This file is part of gr-satellites
#
# SPDX-License-Identifier: GPL-3.0-or-later
#

import struct


class CSP(object):
    def __init__(self, csp_packet):
        if len(csp_packet) < 4:
            raise ValueError('Malformed CSP packet (too short)')
        csp = struct.unpack('!I', csp_packet[0:4])[0]
        self.priority = (csp >> 30) & 0x3
        self.source = (csp >> 25) & 0x1f
        self.destination = (csp >> 20) & 0x1f
        self.dest_port = (csp >> 14) & 0x3f
        self.source_port = (csp >> 8) & 0x3f
        self.reserved = (csp >> 4) & 0xf
        self.hmac = (csp >> 3) & 1
        self.xtea = (csp >> 2) & 1
        self.rdp = (csp >> 1) & 1
        self.crc = csp & 1

    def __str__(self):
        return ("""CSP header:
        Priority:\t\t{}
        Source:\t\t\t{}
        Destination:\t\t{}
        Destination port:\t{}
        Source port:\t\t{}
        Reserved field:\t\t{}
        HMAC:\t\t\t{}
        XTEA:\t\t\t{}
        RDP:\t\t\t{}
        CRC:\t\t\t{}""".format(
            self.priority, self.source, self.destination, self.dest_port,
            self.source_port, self.reserved, self.hmac, self.xtea, self.rdp,
            self.crc))