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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
#
from gnuradio import gr
import numpy
import pmt
from . import csp_header
class swap_crc(gr.basic_block):
"""docstring for block swap_crc"""
def __init__(self):
gr.basic_block.__init__(
self,
name='swap_crc',
in_sig=[],
out_sig=[])
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('out'))
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 = bytes(pmt.u8vector_elements(msg))
try:
header = csp_header.CSP(packet[:4])
except ValueError as e:
return
if not header.crc:
self.message_port_pub(pmt.intern('out'), msg_pmt)
else:
if len(packet) < 8: # 4 bytes CSP header, 4 bytes CRC-32C
# Malformed
return
crc = packet[-4:]
packet = packet[:-4] + crc[::-1]
msg_pmt = pmt.cons(pmt.PMT_NIL,
pmt.init_u8vector(len(packet), packet))
self.message_port_pub(pmt.intern('out'), msg_pmt)
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