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-rw-r--r--src/dabOutput/edi/PFT.cpp327
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diff --git a/src/dabOutput/edi/PFT.cpp b/src/dabOutput/edi/PFT.cpp
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--- a/src/dabOutput/edi/PFT.cpp
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-/*
- Copyright (C) 2019
- Matthias P. Braendli, matthias.braendli@mpb.li
-
- http://www.opendigitalradio.org
-
- 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 ODR-DabMux.
-
- ODR-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.
-
- ODR-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 ODR-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 <stdexcept>
-#include <sstream>
-#include "PFT.h"
-#include "crc.h"
-#include "ReedSolomon.h"
-
-namespace edi {
-
-using namespace std;
-
-// An integer division that rounds up, i.e. ceil(a/b)
-#define CEIL_DIV(a, b) (a % b == 0 ? a / b : a / b + 1)
-
-PFT::PFT() { }
-
-PFT::PFT(const configuration_t &conf) :
- m_k(conf.chunk_len),
- m_m(conf.fec),
- m_dest_port(conf.dest_port),
- m_pseq(0),
- m_num_chunks(0),
- m_verbose(conf.verbose)
- {
- if (m_k > 207) {
- etiLog.level(warn) <<
- "EDI PFT: maximum chunk size is 207.";
- throw std::out_of_range("EDI PFT Chunk size too large.");
- }
-
- if (m_m > 5) {
- etiLog.level(warn) <<
- "EDI PFT: high number of recoverable fragments"
- " may lead to large overhead";
- // See TS 102 821, 7.2.1 Known values, list entry for 'm'
- }
- }
-
-RSBlock PFT::Protect(AFPacket af_packet)
-{
- RSBlock rs_block;
-
- // number of chunks is ceil(afpacketsize / m_k)
- // TS 102 821 7.2.2: c = ceil(l / k_max)
- m_num_chunks = CEIL_DIV(af_packet.size(), m_k);
-
- if (m_verbose) {
- fprintf(stderr, "Protect %zu chunks of size %zu\n",
- m_num_chunks, af_packet.size());
- }
-
- // calculate size of chunk:
- // TS 102 821 7.2.2: k = ceil(l / c)
- // chunk_len does not include the 48 bytes of protection.
- const size_t chunk_len = CEIL_DIV(af_packet.size(), m_num_chunks);
- if (chunk_len > 207) {
- std::stringstream ss;
- ss << "Chunk length " << chunk_len << " too large (>207)";
- throw std::runtime_error(ss.str());
- }
-
- // The last RS chunk is zero padded
- // TS 102 821 7.2.2: z = c*k - l
- const size_t zero_pad = m_num_chunks * chunk_len - af_packet.size();
-
- // Create the RS(k+p,k) encoder
- const int firstRoot = 1; // Discovered by analysing EDI dump
- const int gfPoly = 0x11d;
- const bool reverse = false;
- // The encoding has to be 255, 207 always, because the chunk has to
- // be padded at the end, and not at the beginning as libfec would
- // do
- ReedSolomon rs_encoder(255, 207, reverse, gfPoly, firstRoot);
-
- // add zero padding to last chunk
- for (size_t i = 0; i < zero_pad; i++) {
- af_packet.push_back(0);
- }
-
- if (m_verbose) {
- fprintf(stderr, " add %zu zero padding\n", zero_pad);
- }
-
- // Calculate RS for each chunk and assemble RS block
- for (size_t i = 0; i < af_packet.size(); i+= chunk_len) {
- vector<uint8_t> chunk(207);
- vector<uint8_t> protection(PARITYBYTES);
-
- // copy chunk_len bytes into new chunk
- memcpy(&chunk.front(), &af_packet[i], chunk_len);
-
- // calculate RS for chunk with padding
- rs_encoder.encode(&chunk.front(), &protection.front(), 207);
-
- // Drop the padding
- chunk.resize(chunk_len);
-
- // append new chunk and protection to the RS Packet
- rs_block.insert(rs_block.end(), chunk.begin(), chunk.end());
- rs_block.insert(rs_block.end(), protection.begin(), protection.end());
- }
-
- return rs_block;
-}
-
-vector< vector<uint8_t> > PFT::ProtectAndFragment(AFPacket af_packet)
-{
- const bool enable_RS = (m_m > 0);
-
- if (enable_RS) {
- RSBlock rs_block = Protect(af_packet);
-
-#if 0
- fprintf(stderr, " af_packet (%zu):", af_packet.size());
- for (size_t i = 0; i < af_packet.size(); i++) {
- fprintf(stderr, "%02x ", af_packet[i]);
- }
- fprintf(stderr, "\n");
-
- fprintf(stderr, " rs_block (%zu):", rs_block.size());
- for (size_t i = 0; i < rs_block.size(); i++) {
- fprintf(stderr, "%02x ", rs_block[i]);
- }
- fprintf(stderr, "\n");
-#endif
-
- // TS 102 821 7.2.2: s_max = MIN(floor(c*p/(m+1)), MTU - h))
- const size_t max_payload_size = ( m_num_chunks * PARITYBYTES ) / (m_m + 1);
-
- // Calculate fragment count and size
- // TS 102 821 7.2.2: ceil((l + c*p + z) / s_max)
- // l + c*p + z = length of RS block
- const size_t num_fragments = CEIL_DIV(rs_block.size(), max_payload_size);
-
- // TS 102 821 7.2.2: ceil((l + c*p + z) / f)
- const size_t fragment_size = CEIL_DIV(rs_block.size(), num_fragments);
-
- if (m_verbose)
- fprintf(stderr, " PnF fragment_size %zu, num frag %zu\n",
- fragment_size, num_fragments);
-
- 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++) {
- const size_t ix = j*num_fragments + i;
- if (ix < rs_block.size()) {
- fragments[i][j] = rs_block[ix];
- }
- else {
- fragments[i][j] = 0;
- }
- }
- }
-
- return fragments;
- }
- else { // No RS, only fragmentation
- // TS 102 821 7.2.2: s_max = MTU - h
- // Ethernet MTU is 1500, but maybe you are routing over a network which
- // has some sort of packet encapsulation. Add some margin.
- const size_t max_payload_size = 1400;
-
- // Calculate fragment count and size
- // TS 102 821 7.2.2: ceil((l + c*p + z) / s_max)
- // l + c*p + z = length of AF packet
- const size_t num_fragments = CEIL_DIV(af_packet.size(), max_payload_size);
-
- // TS 102 821 7.2.2: ceil((l + c*p + z) / f)
- const size_t fragment_size = CEIL_DIV(af_packet.size(), num_fragments);
- vector< vector<uint8_t> > fragments(num_fragments);
-
- for (size_t i = 0; i < num_fragments; i++) {
- fragments[i].reserve(fragment_size);
-
- for (size_t j = 0; j < fragment_size; j++) {
- const size_t ix = i*fragment_size + j;
- if (ix < af_packet.size()) {
- fragments[i].push_back(af_packet.at(ix));
- }
- else {
- break;
- }
- }
- }
-
- return fragments;
- }
-}
-
-std::vector< PFTFragment > PFT::Assemble(AFPacket af_packet)
-{
- vector< vector<uint8_t> > fragments = ProtectAndFragment(af_packet);
- vector< vector<uint8_t> > pft_fragments; // These contain PF headers
-
- const bool enable_RS = (m_m > 0);
- const bool enable_transport = true;
-
- unsigned int findex = 0;
-
- unsigned fcount = fragments.size();
-
- // calculate size of chunk:
- // TS 102 821 7.2.2: k = ceil(l / c)
- // chunk_len does not include the 48 bytes of protection.
- const size_t chunk_len = enable_RS ?
- CEIL_DIV(af_packet.size(), m_num_chunks) : 0;
-
- // The last RS chunk is zero padded
- // TS 102 821 7.2.2: z = c*k - l
- const size_t zero_pad = enable_RS ?
- m_num_chunks * chunk_len - af_packet.size() : 0;
-
- for (const auto &fragment : fragments) {
- // Psync
- std::string psync("PF");
- std::vector<uint8_t> packet(psync.begin(), psync.end());
-
- // Pseq
- packet.push_back(m_pseq >> 8);
- packet.push_back(m_pseq & 0xFF);
-
- // Findex
- packet.push_back(findex >> 16);
- packet.push_back(findex >> 8);
- packet.push_back(findex & 0xFF);
- findex++;
-
- // Fcount
- packet.push_back(fcount >> 16);
- packet.push_back(fcount >> 8);
- packet.push_back(fcount & 0xFF);
-
- // RS (1 bit), transport (1 bit) and Plen (14 bits)
- unsigned int plen = fragment.size();
- if (enable_RS) {
- plen |= 0x8000; // Set FEC bit
- }
-
- if (enable_transport) {
- plen |= 0x4000; // Set ADDR bit
- }
-
- packet.push_back(plen >> 8);
- packet.push_back(plen & 0xFF);
-
- if (enable_RS) {
- packet.push_back(chunk_len); // RSk
- packet.push_back(zero_pad); // RSz
- }
-
- if (enable_transport) {
- // Source (16 bits)
- uint16_t addr_source = 0;
- packet.push_back(addr_source >> 8);
- packet.push_back(addr_source & 0xFF);
-
- // Dest (16 bits)
- packet.push_back(m_dest_port >> 8);
- packet.push_back(m_dest_port & 0xFF);
- }
-
- // calculate CRC over AF Header and payload
- uint16_t crc = 0xffff;
- crc = crc16(crc, &(packet.front()), packet.size());
- crc ^= 0xffff;
-
- 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);
-
-#if 0
- fprintf(stderr, "* PFT pseq %d, findex %d, fcount %d, plen %d\n",
- m_pseq, findex, fcount, plen & ~0xC000);
-#endif
- }
-
- m_pseq++;
-
- return pft_fragments;
-}
-
-}
-
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