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/*
Copyright (C) 2021
Matthias P. Braendli, matthias.braendli@mpb.li
http://www.opendigitalradio.org
EDI output.
This implements an AF Packet as defined ETSI TS 102 821.
Also see ETSI TS 102 693
*/
/*
This file is part of the ODR-mmbTools.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "crc.h"
#include "AFPacket.h"
#include "TagItems.h"
#include "TagPacket.h"
#include <vector>
#include <string>
#include <iostream>
#include <cstdio>
#include <cstdint>
#include <arpa/inet.h>
namespace edi {
// Header PT field. AF packet contains TAG payload
const uint8_t AFHEADER_PT_TAG = 'T';
// AF Packet Major (3 bits) and Minor (4 bits) version
const uint8_t AFHEADER_VERSION = 0x10; // MAJ=1, MIN=0
AFPacket AFPacketiser::Assemble(TagPacket tag_packet)
{
std::vector<uint8_t> payload = tag_packet.Assemble();
if (m_verbose)
std::cerr << "Assemble AFPacket " << m_seq << std::endl;
std::string pack_data("AF"); // SYNC
std::vector<uint8_t> packet(pack_data.begin(), pack_data.end());
uint32_t taglength = payload.size();
if (m_verbose)
std::cerr << " AFPacket payload size " << payload.size() << std::endl;
// write length into packet
packet.push_back((taglength >> 24) & 0xFF);
packet.push_back((taglength >> 16) & 0xFF);
packet.push_back((taglength >> 8) & 0xFF);
packet.push_back(taglength & 0xFF);
// fill rest of header
packet.push_back(m_seq >> 8);
packet.push_back(m_seq & 0xFF);
m_seq++;
packet.push_back((m_have_crc ? 0x80 : 0) | AFHEADER_VERSION); // ar_cf: CRC=1
packet.push_back(AFHEADER_PT_TAG);
// insert payload, must have a length multiple of 8 bytes
packet.insert(packet.end(), payload.begin(), payload.end());
// calculate CRC over AF Header and payload
uint16_t crc = 0xffff;
crc = crc16(crc, &(packet.front()), packet.size());
crc ^= 0xffff;
if (m_verbose)
fprintf(stderr, " AFPacket crc %x\n", crc);
packet.push_back((crc >> 8) & 0xFF);
packet.push_back(crc & 0xFF);
if (m_verbose)
std::cerr << " AFPacket length " << packet.size() << std::endl;
return packet;
}
void AFPacketiser::OverrideSeq(uint16_t seq)
{
m_seq = seq;
}
}
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