Send the program type indicated in the SIG

argilo · Aug 1, 2023 · c13100c · c13100c
1 parent 92e56c0
commit c13100c
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Showing 3 changed files with 41 additions and 5 deletions.
diff --git a/README.md b/README.md
@@ -90,6 +90,8 @@ This block assembles HDC audio frames and PSD PDUs into the audio transport, pro
 
 The "Data bytes" setting controls how many bytes of each layer 2 PDU are set aside for Advanced Application Services (AAS) data.
 
+The Layer 2 encoder gets program type information from the SIS & SIG encoder via the "aas" message port, so this port should be connected even when "Data bytes" is set to zero.
+
 ### Layer 1 FM encoder
 
 This block implements Layer 1 FM (as defined in https://www.nrscstandards.org/standards-and-guidelines/documents/standards/nrsc-5-d/reference-docs/1011s.pdf). It takes PIDS and Layer 2 PDUs as input, and produces OFDM symbols as output. Only the Hybrid and Extended Hybrid modes have been implemented and tested so far. The All Digital modes are currently under development.

diff --git a/lib/l2_encoder_impl.cc b/lib/l2_encoder_impl.cc
@@ -51,6 +51,7 @@ l2_encoder_impl::l2_encoder_impl(const int num_progs,
 
     this->num_progs = num_progs;
     this->first_prog = first_prog;
+    memset(program_type, 0, sizeof(program_type));
     this->size = size;
     this->data_bytes = data_bytes;
     payload_bytes = (size - 22) / 8;
@@ -125,8 +126,8 @@ int l2_encoder_impl::general_work(int noutput_items,
     const unsigned char** psd = (const unsigned char**)&input_items[num_progs];
     unsigned char* out = (unsigned char*)output_items[0];
 
-    int hdc_off[8] = { 0 };
-    int psd_off[8] = { 0 };
+    int hdc_off[MAX_PROGRAMS] = { 0 };
+    int psd_off[MAX_PROGRAMS] = { 0 };
 
     for (int out_off = 0; out_off < noutput_items * size; out_off += size) {
         memset(out_buf, 0, payload_bytes);
@@ -218,7 +219,7 @@ int l2_encoder_impl::general_work(int noutput_items,
             write_hef(out_program + 14 + len_locators(nop),
                       program_number,
                       /*access*/ 0,
-                      /*program_type*/ 0);
+                      program_type[program_number]);
 
             memcpy(out_program + (14 + len_locators(nop) + 3),
                    psd[p] + psd_off[p],
@@ -454,12 +455,39 @@ void l2_encoder_impl::handle_aas_pdu(pmt::pmt_t msg)
     std::vector<unsigned char> pdu_bytes = pmt::u8vector_elements(pmt::cdr(msg));
     int port = (pdu_bytes[2] << 8) | pdu_bytes[1];
 
+    if ((pdu_bytes[0] == AAS_PACKET_FORMAT) && (port == SIG_PORT)) {
+        decode_sig(pdu_bytes);
+    }
+
     std::vector<unsigned char> pdu_encoded = hdlc_encode(pdu_bytes);
 
     for (auto c : pdu_encoded) {
         aas_queues[port].push(c);
     }
 }
 
+void l2_encoder_impl::decode_sig(std::vector<unsigned char>& pdu_bytes)
+{
+    int offset = 5;
+    while (offset < pdu_bytes.size()) {
+        unsigned char type = pdu_bytes[offset++];
+        switch (type & 0xf0) {
+        case 0x40:
+            offset += 3;
+            break;
+        case 0x60:
+            unsigned char length = pdu_bytes[offset++];
+            if (type == 0x66) {
+                unsigned char port = pdu_bytes[offset + 1];
+                unsigned char type = pdu_bytes[offset + 2];
+                if (port < MAX_PROGRAMS) {
+                    program_type[port] = type;
+                }
+            }
+            offset += length - 1;
+        }
+    }
+}
+
 } /* namespace nrsc5 */
 } /* namespace gr */
diff --git a/lib/l2_encoder_impl.h b/lib/l2_encoder_impl.h
@@ -50,11 +50,16 @@ constexpr unsigned char CRC8_TABLE[] = {
 
 constexpr unsigned char BBM[] = { 0x7d, 0x3a, 0xe2, 0x42 };
 
+constexpr int MAX_PROGRAMS = 8;
+constexpr uint8_t AAS_PACKET_FORMAT = 0x21;
+constexpr uint16_t SIG_PORT = 0x20;
+
 class l2_encoder_impl : public l2_encoder
 {
 private:
     int num_progs;
     int first_prog;
+    int program_type[MAX_PROGRAMS];
     int size;
     int data_bytes;
     int payload_bytes;
@@ -66,9 +71,9 @@ class l2_encoder_impl : public l2_encoder
     int pdu_seq_no;
     int pdu_seq_len;
     int codec_mode;
-    int start_seq_no[8];
+    int start_seq_no[MAX_PROGRAMS];
     int target_seq_no;
-    int partial_bytes[8];
+    int partial_bytes[MAX_PROGRAMS];
     int ccc_width;
     unsigned char ccc_count;
     std::vector<unsigned char> ccc;
@@ -101,6 +106,7 @@ class l2_encoder_impl : public l2_encoder
     int adts_length(const unsigned char* header);
     int len_locators(int nop);
     void handle_aas_pdu(pmt::pmt_t msg);
+    void decode_sig(std::vector<unsigned char>& pdu_bytes);
 
 public:
     l2_encoder_impl(const int num_progs,