diff options
Diffstat (limited to 'src/dabOutput')
| -rw-r--r-- | src/dabOutput/edi/PFT.cpp | 62 | ||||
| -rw-r--r-- | src/dabOutput/edi/PFT.h | 8 |
2 files changed, 70 insertions, 0 deletions
diff --git a/src/dabOutput/edi/PFT.cpp b/src/dabOutput/edi/PFT.cpp index eba8ac0..e04ffab 100644 --- a/src/dabOutput/edi/PFT.cpp +++ b/src/dabOutput/edi/PFT.cpp @@ -34,7 +34,9 @@ #include <cstdio> #include <cstring> #include <stdint.h> +#include <arpa/inet.h> #include "PFT.h" +#include "crc.h" #include "ReedSolomon.h" using namespace std; @@ -98,3 +100,63 @@ vector< vector<uint8_t> > PFT::ProtectAndFragment(AFPacket af_packet) 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; +} + diff --git a/src/dabOutput/edi/PFT.h b/src/dabOutput/edi/PFT.h index 55ca569..49bb7b7 100644 --- a/src/dabOutput/edi/PFT.h +++ b/src/dabOutput/edi/PFT.h @@ -41,6 +41,7 @@ #include "ReedSolomon.h" typedef std::vector<uint8_t> RSPacket; +typedef std::vector<uint8_t> PFTFragment; class PFT { @@ -50,6 +51,7 @@ class PFT PFT(unsigned int RSDataWordLength, unsigned int NumRecoverableFragments) : m_k(RSDataWordLength), m_m(NumRecoverableFragments), + m_pseq(0), m_encoder(m_k + ParityBytes, m_k) { if (m_k > 207) { @@ -66,6 +68,10 @@ class PFT } } + // return a list of PFT fragments with the correct + // PFT headers + std::vector< PFTFragment > Assemble(AFPacket af_packet); + // Apply Reed-Solomon FEC to the AF Packet RSPacket Protect(AFPacket af_packet); @@ -76,6 +82,8 @@ class PFT unsigned int m_k; // length of RS data word unsigned int m_m; // number of fragments that can be recovered if lost + uint16_t m_pseq; + size_t m_num_chunks; ReedSolomon m_encoder; |