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-rw-r--r--src/dabOutput/edi/PFT.cpp109
-rw-r--r--src/dabOutput/edi/PFT.h9
-rw-r--r--src/dabOutput/edi/TagItems.cpp6
3 files changed, 87 insertions, 37 deletions
diff --git a/src/dabOutput/edi/PFT.cpp b/src/dabOutput/edi/PFT.cpp
index 5eaac09..4578392 100644
--- a/src/dabOutput/edi/PFT.cpp
+++ b/src/dabOutput/edi/PFT.cpp
@@ -41,52 +41,88 @@
using namespace std;
-typedef vector<uint8_t> Chunk;
+// An integer division that rounds up, i.e. ceil(a/b)
+#define CEIL_DIV(a, b) (a % b == 0 ? a / b : a / b + 1)
-
-RSPacket PFT::Protect(AFPacket af_packet)
+RSBlock PFT::Protect(AFPacket af_packet)
{
- RSPacket rs_packet;
+ RSBlock rs_block;
// 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;
+ // TS 102 821 7.2.2: c = ceil(l / k_max)
+ m_num_chunks = CEIL_DIV(af_packet.size(), 207);
+
+ if (m_verbose) {
+ fprintf(stderr, "Protect %zu chunks of size %zu\n",
+ m_num_chunks, af_packet.size());
}
- const size_t zero_pad = m_num_chunks * m_k - 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);
+
+ // 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
+ ReedSolomon rs_encoder(chunk_len + ParityBytes, chunk_len);
// 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);
+ 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(chunk_len + ParityBytes);
- // copy m_k bytes into new chunk
- memcpy(&c.front(), &af_packet[i], m_k);
+ // copy chunk_len bytes into new chunk
+ memcpy(&chunk.front(), &af_packet[i], chunk_len);
// calculate RS for chunk
- m_encoder.encode(&c.front(), c.size());
+ rs_encoder.encode(&chunk.front(), chunk.size());
// append new chunk to the RS Packet
- rs_packet.insert(rs_packet.end(), c.begin(), c.end());
+ rs_block.insert(rs_block.end(), chunk.begin(), chunk.end());
}
- return rs_packet;
+ return rs_block;
}
vector< vector<uint8_t> > PFT::ProtectAndFragment(AFPacket af_packet)
{
- RSPacket rs_packet = Protect(af_packet);
+ 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);
- 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;
+ // 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",
@@ -97,7 +133,12 @@ vector< vector<uint8_t> > PFT::ProtectAndFragment(AFPacket af_packet)
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];
+ if (j*num_fragments + i > rs_block.size()) {
+ fragments[i][j] = 0;
+ }
+ else {
+ fragments[i][j] = rs_block[j*num_fragments + i];
+ }
}
}
@@ -107,13 +148,20 @@ vector< vector<uint8_t> > PFT::ProtectAndFragment(AFPacket af_packet)
std::vector< PFTFragment > PFT::Assemble(AFPacket af_packet)
{
vector< vector<uint8_t> > fragments = ProtectAndFragment(af_packet);
- vector< vector<uint8_t> > pft_fragments;
+ vector< vector<uint8_t> > pft_fragments; // These contain PF headers
unsigned int findex = 0;
unsigned fcount = fragments.size();
- const size_t zero_pad = m_num_chunks * m_k - 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);
+
+ // 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();
for (size_t i = 0; i < fragments.size(); i++) {
const vector<uint8_t>& fragment = fragments[i];
@@ -136,11 +184,11 @@ std::vector< PFTFragment > PFT::Assemble(AFPacket af_packet)
unsigned int plen = fragment.size();
plen |= 0x8000; // Set FEC bit
- packet.push_back(plen >> 8); // RSk
- packet.push_back(plen & 0xFF); // RSz
+ packet.push_back(plen >> 8);
+ packet.push_back(plen & 0xFF);
- packet.push_back(m_k);
- packet.push_back(zero_pad);
+ packet.push_back(chunk_len); // RSk
+ packet.push_back(zero_pad); // RSz
// calculate CRC over AF Header and payload
uint16_t crc = 0xffff;
@@ -155,9 +203,10 @@ std::vector< PFTFragment > PFT::Assemble(AFPacket af_packet)
pft_fragments.push_back(packet);
- if (m_verbose)
- fprintf(stderr, "* PFT pseq %d, findex %d, fcount %d, plen %d\n",
- m_pseq, findex, fcount, plen & ~0x8000);
+#if 0
+ fprintf(stderr, "* PFT pseq %d, findex %d, fcount %d, plen %d\n",
+ m_pseq, findex, fcount, plen & ~0x8000);
+#endif
}
m_pseq++;
diff --git a/src/dabOutput/edi/PFT.h b/src/dabOutput/edi/PFT.h
index 02380ec..1d09c0b 100644
--- a/src/dabOutput/edi/PFT.h
+++ b/src/dabOutput/edi/PFT.h
@@ -40,7 +40,7 @@
#include "Log.h"
#include "ReedSolomon.h"
-typedef std::vector<uint8_t> RSPacket;
+typedef std::vector<uint8_t> RSBlock;
typedef std::vector<uint8_t> PFTFragment;
class PFT
@@ -54,7 +54,6 @@ class PFT
m_k(RSDataWordLength),
m_m(NumRecoverableFragments),
m_pseq(0),
- m_encoder(m_k + ParityBytes, m_k),
m_verbose(verbose)
{
if (m_k > 207) {
@@ -76,9 +75,9 @@ class PFT
std::vector< PFTFragment > Assemble(AFPacket af_packet);
// Apply Reed-Solomon FEC to the AF Packet
- RSPacket Protect(AFPacket af_packet);
+ RSBlock Protect(AFPacket af_packet);
- // Cut a RSPacket into several fragments that can be transmitted
+ // Cut a RSBlock into several fragments that can be transmitted
std::vector< std::vector<uint8_t> > ProtectAndFragment(AFPacket af_packet);
private:
@@ -89,8 +88,6 @@ class PFT
size_t m_num_chunks;
- ReedSolomon m_encoder;
-
bool m_verbose;
};
diff --git a/src/dabOutput/edi/TagItems.cpp b/src/dabOutput/edi/TagItems.cpp
index 488f8c3..2cae7d1 100644
--- a/src/dabOutput/edi/TagItems.cpp
+++ b/src/dabOutput/edi/TagItems.cpp
@@ -70,7 +70,11 @@ std::vector<uint8_t> TagDETI::Assemble()
packet.push_back(0);
packet.push_back(0);
- uint16_t detiHeader = dflc | (rfudf << 13) | (ficf << 14) | (atstf << 15);
+ uint8_t fct = dflc % 250;
+ uint8_t fcth = dflc / 250;
+
+
+ uint16_t detiHeader = fct | (fcth << 8) | (rfudf << 13) | (ficf << 14) | (atstf << 15);
packet.push_back(detiHeader >> 8);
packet.push_back(detiHeader & 0xFF);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-11 08:04:03 +0000