refactoring to support QAM16 LDPC decode

7 files changed, 24 insertions, 30 deletions

diff --git a/src/freedv_2020.c b/src/freedv_2020.c
index 9963819..83e1f54 100644
--- a/src/freedv_2020.c
+++ b/src/freedv_2020.c
@@ -286,7 +286,7 @@ int freedv_comprx_2020(struct freedv *f, COMP demod_in[]) {
     }
 
     symbols_to_llrs(llr, codeword_symbols_de, codeword_amps_de, EsNo,
-                    ofdm->mean_amp, coded_syms_per_frame);
+                    ofdm->mean_amp, ofdm->bps, coded_syms_per_frame);
     ldpc_decode_frame(ldpc, &parityCheckCount, &iter, out_char, llr);
     if (parityCheckCount != ldpc->NumberParityBits)
       rx_status |= FREEDV_RX_BIT_ERRORS;
diff --git a/src/freedv_700.c b/src/freedv_700.c
index 257b80f..40aa2c0 100644
--- a/src/freedv_700.c
+++ b/src/freedv_700.c
@@ -504,7 +504,7 @@ int freedv_comp_short_rx_ofdm(struct freedv *f, void *demod_in_8kHz,
       float llr[Npayloadbitsperpacket];
       uint8_t decoded_codeword[Npayloadbitsperpacket];
       symbols_to_llrs(llr, payload_syms_de, payload_amps_de, EsNo,
-                      ofdm->mean_amp, Npayloadsymsperpacket);
+                      ofdm->mean_amp, ofdm->bps, Npayloadsymsperpacket);
       ldpc_decode_frame(ldpc, &parityCheckCount, &iter, decoded_codeword, llr);
       // iter = run_ldpc_decoder(ldpc, decoded_codeword, llr,
       // &parityCheckCount);
diff --git a/src/mpdecode_core.c b/src/mpdecode_core.c
index 5374255..65b2be6 100644
--- a/src/mpdecode_core.c
+++ b/src/mpdecode_core.c
@@ -565,17 +565,14 @@ void sd_to_llr(float llr[], float sd[], int n) {
 */
 
 void Demod2D(float symbol_likelihood[], /* output, M*number_symbols */
-             COMP r[],        /* received QPSK symbols, number_symbols */
-             COMP S_matrix[], /* constellation of size M               */
-             float EsNo,
-             float fading[], /* real fading values, number_symbols    */
+             COMP r[],        /* received PSK symbols, number_symbols */
+             COMP S_matrix[], /* constellation of size M */
+             int M, float EsNo,
+             float fading[], /* real fading values, number_symbols */
              float mean_amp, int number_symbols) {
-  int M = QPSK_CONSTELLATION_SIZE;
   int i, j;
   float tempsr, tempsi, Er, Ei;
 
-  /* determine output */
-
   for (i = 0; i < number_symbols; i++) { /* go through each received symbol */
     for (j = 0; j < M; j++) {            /* each postulated symbol          */
       tempsr = fading[i] * S_matrix[j].real / mean_amp;
@@ -583,10 +580,7 @@ void Demod2D(float symbol_likelihood[], /* output, M*number_symbols */
       Er = r[i].real / mean_amp - tempsr;
       Ei = r[i].imag / mean_amp - tempsi;
       symbol_likelihood[i * M + j] = -EsNo * (Er * Er + Ei * Ei);
-      // printf("symbol_likelihood[%d][%d] = %f\n",
-      // i,j,symbol_likelihood[i*M+j]);
     }
-    // exit(0);
   }
 }
 
@@ -633,18 +627,17 @@ void Somap(float bit_likelihood[],    /* number_bits, bps*number_symbols */
   }
 }
 
-void symbols_to_llrs(float llr[], COMP rx_qpsk_symbols[], float rx_amps[],
-                     float EsNo, float mean_amp, int nsyms) {
+void symbols_to_llrs(float llr[], COMP rx_psk_symbols[], float rx_amps[],
+                     float EsNo, float mean_amp, int bps, int nsyms) {
   int i;
-
-  float symbol_likelihood[nsyms * QPSK_CONSTELLATION_SIZE];
-  float bit_likelihood[nsyms * QPSK_BITS_PER_SYMBOL];
-
-  Demod2D(symbol_likelihood, rx_qpsk_symbols, S_matrix, EsNo, rx_amps, mean_amp,
-          nsyms);
-  Somap(bit_likelihood, symbol_likelihood, QPSK_CONSTELLATION_SIZE,
-        QPSK_BITS_PER_SYMBOL, nsyms);
-  for (i = 0; i < nsyms * QPSK_BITS_PER_SYMBOL; i++) {
+  int constellation_points = 1 << bps;
+  float symbol_likelihood[nsyms * constellation_points];
+  float bit_likelihood[nsyms * bps];
+
+  Demod2D(symbol_likelihood, rx_psk_symbols, S_matrix, constellation_points,
+          EsNo, rx_amps, mean_amp, nsyms);
+  Somap(bit_likelihood, symbol_likelihood, constellation_points, bps, nsyms);
+  for (i = 0; i < nsyms * bps; i++) {
     llr[i] = -bit_likelihood[i];
   }
 }
diff --git a/src/mpdecode_core.h b/src/mpdecode_core.h
index 95ead46..d36a1f0 100644
--- a/src/mpdecode_core.h
+++ b/src/mpdecode_core.h
@@ -47,12 +47,12 @@ int run_ldpc_decoder(struct LDPC *ldpc, uint8_t out_char[], float input[],
                      int *parityCheckCount);
 
 void sd_to_llr(float llr[], float sd[], int n);
-void Demod2D(float symbol_likelihood[], COMP r[], COMP S_matrix[], float EsNo,
-             float fading[], float mean_amp, int number_symbols);
+void Demod2D(float symbol_likelihood[], COMP r[], COMP S_matrix[], int M,
+             float EsNo, float fading[], float mean_amp, int number_symbols);
 void Somap(float bit_likelihood[], float symbol_likelihood[], int M, int bps,
            int number_symbols);
 void symbols_to_llrs(float llr[], COMP rx_qpsk_symbols[], float rx_amps[],
-                     float EsNo, float mean_amp, int nsyms);
+                     float EsNo, float mean_amp, int bps, int nsyms);
 void fsk_rx_filt_to_llrs(float llr[], float rx_filt[], float v_est,
                          float SNRest, int M, int nsyms);
 
diff --git a/src/ofdm_demod.c b/src/ofdm_demod.c
index f8dc7a5..e855e5e 100644
--- a/src/ofdm_demod.c
+++ b/src/ofdm_demod.c
@@ -500,7 +500,7 @@ int main(int argc, char *argv[]) {
           }
 
           symbols_to_llrs(llr, payload_syms_de, payload_amps_de, EsNo,
-                          ofdm->mean_amp, Npayloadsymsperpacket);
+                          ofdm->mean_amp, ofdm->bps, Npayloadsymsperpacket);
 
           assert(Ndatabitsperpacket == ldpc.data_bits_per_frame);
           ldpc_decode_frame(&ldpc, &parityCheckCount, &iter, out_char, llr);
diff --git a/src/reliable_text.c b/src/reliable_text.c
index 8a5ba21..ff7c5c0 100644
--- a/src/reliable_text.c
+++ b/src/reliable_text.c
@@ -182,7 +182,8 @@ static int reliable_text_ldpc_decode(reliable_text_impl_t* obj, char* dest) {
     float EsNo = 3.0;  // note: constant from freedv_700.c
 
     symbols_to_llrs(llr, (COMP*)deinterleavedSyms, deinterleavedAmps, EsNo,
-                    obj->fdv->ofdm->mean_amp, Npayloadsymsperpacket);
+                    obj->fdv->ofdm->mean_amp, obj->fdv->ofdm->bps,
+                    Npayloadsymsperpacket);
   } else {
     // Deinterlace the received bits.
     gp_deinterleave_bits(deinterleavedBits, src, LDPC_TOTAL_SIZE_BITS / 2);
diff --git a/unittest/tofdm.c b/unittest/tofdm.c
index 0efcc60..a6b139f 100644
--- a/unittest/tofdm.c
+++ b/unittest/tofdm.c
@@ -475,8 +475,8 @@ int main(int argc, char *argv[]) {
       float *ldpc_codeword_symbol_amps =
           &ofdm->rx_amp[(ofdm_nuwbits + ofdm_ntxtbits) / ofdm_bps];
 
-      Demod2D(symbol_likelihood, ldpc_codeword_symbols, S_matrix, EsNo,
-              ldpc_codeword_symbol_amps, ofdm->mean_amp,
+      Demod2D(symbol_likelihood, ldpc_codeword_symbols, S_matrix, 1 << ofdm_bps,
+              EsNo, ldpc_codeword_symbol_amps, ofdm->mean_amp,
               CODED_BITSPERFRAME / ofdm_bps);
       Somap(bit_likelihood, symbol_likelihood, 1 << ofdm_bps, ofdm_bps,
             CODED_BITSPERFRAME / ofdm_bps);