Add PFT Fragment header

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;