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#!/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
from gnuradio import gr
import numpy
import pmt
from . import crc32c
from . import csp_header
class check_crc(gr.basic_block):
"""docstring for block check_crc"""
def __init__(self, include_header, verbose, force=False):
gr.basic_block.__init__(
self,
name='check_crc',
in_sig=[],
out_sig=[])
self.include_header = include_header
self.verbose = verbose
self.force = force
self.message_port_register_in(pmt.intern('in'))
self.set_msg_handler(pmt.intern('in'), self.handle_msg)
self.message_port_register_out(pmt.intern('ok'))
self.message_port_register_out(pmt.intern('fail'))
def handle_msg(self, msg_pmt):
msg = pmt.cdr(msg_pmt)
if not pmt.is_u8vector(msg):
print('[ERROR] Received invalid message type. Expected u8vector')
return
packet = pmt.u8vector_elements(msg)
try:
header = csp_header.CSP(packet[:4])
except ValueError as e:
if self.verbose:
print(e)
return
if not self.force and not header.crc:
if self.verbose:
print('CRC not used')
self.message_port_pub(pmt.intern('ok'), msg_pmt)
else:
if len(packet) < 8: # 4 bytes CSP header, 4 bytes CRC-32C
if self.verbose:
print('Malformed CSP packet (too short)')
return
crc = crc32c.crc(packet[:-4]
if self.include_header
else packet[4:-4])
packet_crc = struct.unpack('>I', bytes(packet[-4:]))[0]
if crc == packet_crc:
if self.verbose:
print('CRC OK')
self.message_port_pub(pmt.intern('ok'), msg_pmt)
else:
if self.verbose:
print('CRC failed')
self.message_port_pub(pmt.intern('fail'), msg_pmt)
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