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/*
Copyright (C) 2013 Matthias P. Braendli
http://mpb.li
EDI output,
Protection, Fragmentation and Transport. (PFT)
Are supported:
Reed-Solomon and Fragmentation
This implements part of PFT as defined ETSI TS 102 821.
*/
/*
This file is part of CRC-DabMux.
CRC-DabMux 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.
CRC-DabMux 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 CRC-DabMux. If not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <vector>
#include <list>
#include <cstdio>
#include <cstring>
#include <stdint.h>
#include <arpa/inet.h>
#include "PFT.h"
#include "crc.h"
#include "ReedSolomon.h"
using namespace std;
typedef vector<uint8_t> Chunk;
RSPacket PFT::Protect(AFPacket af_packet)
{
RSPacket rs_packet;
// number of chunks is ceil(afpacketsize / m_k)
if (af_packet.size() % m_k == 0) {
m_num_chunks = af_packet.size() / m_k;
}
else {
m_num_chunks = af_packet.size() / m_k + 1;
}
const size_t zero_pad = m_num_chunks * m_k - af_packet.size();
// add zero padding to last chunk
for (size_t i = 0; i < zero_pad; i++) {
af_packet.push_back(0);
}
for (size_t i = 1; i < af_packet.size(); i+= m_k) {
Chunk c(m_k + ParityBytes);
// copy m_k bytes into new chunk
memcpy(&c.front(), &af_packet[i], m_k);
// calculate RS for chunk
m_encoder.encode(&c.front(), c.size());
// append new chunk to the RS Packet
rs_packet.insert(rs_packet.end(), c.begin(), c.end());
}
return rs_packet;
}
vector< vector<uint8_t> > PFT::ProtectAndFragment(AFPacket af_packet)
{
RSPacket rs_packet = Protect(af_packet);
const size_t max_payload_size = ( m_num_chunks * ParityBytes ) / (m_m + 1);
const size_t fragment_size = m_num_chunks * (m_k + ParityBytes) / max_payload_size;
const size_t num_fragments = m_num_chunks * (m_k + ParityBytes) / fragment_size;
vector< vector<uint8_t> > fragments(num_fragments);
for (size_t i = 0; i < num_fragments; i++) {
fragments[i].resize(fragment_size);
for (size_t j = 0; j < fragment_size; j++) {
fragments[i][j] = rs_packet[j*num_fragments + i];
}
}
return fragments;
}
std::vector< PFTFragment > PFT::Assemble(AFPacket af_packet)
{
vector< vector<uint8_t> > fragments = ProtectAndFragment(af_packet);
vector< vector<uint8_t> > pft_fragments;
unsigned int findex = 0;
unsigned fcount = fragments.size();
const size_t zero_pad = m_num_chunks * m_k - af_packet.size();
for (size_t i = 0; i < fragments.size(); i++) {
const vector<uint8_t>& fragment = fragments[i];
std::string psync("PF"); // SYNC
std::vector<uint8_t> packet(psync.begin(), psync.end());
packet.push_back(m_pseq >> 8);
packet.push_back(m_pseq & 0xFF);
m_pseq++;
packet.push_back(findex >> 16);
packet.push_back(findex >> 8);
packet.push_back(findex & 0xFF);
findex++;
packet.push_back(fcount >> 16);
packet.push_back(fcount >> 8);
packet.push_back(fcount & 0xFF);
unsigned int plen = fragment.size();
plen |= 0x8000; // Set FEC bit
packet.push_back(plen >> 16);
packet.push_back(plen >> 8);
packet.push_back(plen & 0xFF);
packet.push_back(m_k);
packet.push_back(zero_pad);
// calculate CRC over AF Header and payload
uint16_t crc = 0xffff;
crc = crc16(crc, &(packet.back()), packet.size());
crc ^= 0xffff;
crc = htons(crc);
packet.push_back((crc >> 24) & 0xFF);
packet.push_back((crc >> 16) & 0xFF);
packet.push_back((crc >> 8) & 0xFF);
packet.push_back(crc & 0xFF);
// insert payload, must have a length multiple of 8 bytes
packet.insert(packet.end(), fragment.begin(), fragment.end());
pft_fragments.push_back(packet);
}
return pft_fragments;
}
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