From 2574de4d2db73d8f068bbcedbf6ab7c040fbfdf6 Mon Sep 17 00:00:00 2001
From: Guillem Foreman <guillem.foreman@softwareradiosystems.com>
Date: Tue, 16 Jul 2019 17:01:20 +0200
Subject: [PATCH] Fixed soft demodulator

---
 lib/src/phy/modem/demod_soft.c      | 81 +++++++++++++++++------------
 lib/src/phy/modem/test/modem_test.c | 23 ++++----
 2 files changed, 57 insertions(+), 47 deletions(-)

diff --git a/lib/src/phy/modem/demod_soft.c b/lib/src/phy/modem/demod_soft.c
index 350cc153a..f63f6f9e3 100644
--- a/lib/src/phy/modem/demod_soft.c
+++ b/lib/src/phy/modem/demod_soft.c
@@ -413,51 +413,66 @@ void demod_64qam_lte_b(const cf_t *symbols, int8_t *llr, int nsymbols)
 void demod_256qam_lte(const cf_t* symbols, float* llr, int nsymbols)
 {
   for (int i = 0; i < nsymbols; i++) {
-    float real = crealf(symbols[i]);
-    float imag = cimagf(symbols[i]);
-
-    llr[8 * i + 0] = -real;
-    llr[8 * i + 1] = -imag;
-    llr[8 * i + 2] = fabsf(real) - 8 / sqrt(170);
-    llr[8 * i + 3] = fabsf(imag) - 8 / sqrt(170);
-    llr[8 * i + 4] = fabsf(llr[8 * i + 2]) - 4 / sqrt(170);
-    llr[8 * i + 5] = fabsf(llr[8 * i + 3]) - 4 / sqrt(170);
-    llr[8 * i + 6] = fabsf(llr[8 * i + 4]) - 2 / sqrt(170);
-    llr[8 * i + 7] = fabsf(llr[8 * i + 5]) - 2 / sqrt(170);
+    float real = -__real__ symbols[i];
+    float imag = -__imag__ symbols[i];
+    *(llr++)   = real;
+    *(llr++)   = imag;
+    real       = fabsf(real) - 8.0f / sqrtf(170.0f);
+    imag       = fabsf(imag) - 8.0f / sqrtf(170.0f);
+    *(llr++)   = real;
+    *(llr++)   = imag;
+    real       = fabsf(real) - 4.0f / sqrtf(170.0f);
+    imag       = fabsf(imag) - 4.0f / sqrtf(170.0f);
+    *(llr++)   = real;
+    *(llr++)   = imag;
+    real       = fabsf(real) - 2.0f / sqrtf(170.0f);
+    imag       = fabsf(imag) - 2.0f / sqrtf(170.0f);
+    *(llr++)   = real;
+    *(llr++)   = imag;
   }
 }
 
 void demod_256qam_lte_b(const cf_t* symbols, int8_t* llr, int nsymbols)
 {
   for (int i = 0; i < nsymbols; i++) {
-    float real = SCALE_BYTE_CONV_QAM256 * crealf(symbols[i]);
-    float imag = SCALE_BYTE_CONV_QAM256 * cimagf(symbols[i]);
-
-    llr[8 * i + 0] = -real;
-    llr[8 * i + 1] = -imag;
-    llr[8 * i + 2] = fabsf(real) - SCALE_BYTE_CONV_QAM256 * 8 / sqrt(170);
-    llr[8 * i + 3] = fabsf(imag) - SCALE_BYTE_CONV_QAM256 * 8 / sqrt(170);
-    llr[8 * i + 4] = fabsf(llr[8 * i + 2]) - SCALE_BYTE_CONV_QAM256 * 4 / sqrt(170);
-    llr[8 * i + 5] = fabsf(llr[8 * i + 3]) - SCALE_BYTE_CONV_QAM256 * 4 / sqrt(170);
-    llr[8 * i + 6] = fabsf(llr[8 * i + 4]) - SCALE_BYTE_CONV_QAM256 * 2 / sqrt(170);
-    llr[8 * i + 7] = fabsf(llr[8 * i + 5]) - SCALE_BYTE_CONV_QAM256 * 2 / sqrt(170);
+    float real = -__real__ symbols[i];
+    float imag = -__imag__ symbols[i];
+    *(llr++)   = SCALE_BYTE_CONV_QAM256 * real;
+    *(llr++)   = SCALE_BYTE_CONV_QAM256 * imag;
+    real       = fabsf(real) - 8.0f / sqrtf(170.0f);
+    imag       = fabsf(imag) - 8.0f / sqrtf(170.0f);
+    *(llr++)   = SCALE_BYTE_CONV_QAM256 * real;
+    *(llr++)   = SCALE_BYTE_CONV_QAM256 * imag;
+    real       = fabsf(real) - 4.0f / sqrtf(170.0f);
+    imag       = fabsf(imag) - 4.0f / sqrtf(170.0f);
+    *(llr++)   = SCALE_BYTE_CONV_QAM256 * real;
+    *(llr++)   = SCALE_BYTE_CONV_QAM256 * imag;
+    real       = fabsf(real) - 2.0f / sqrtf(170.0f);
+    imag       = fabsf(imag) - 2.0f / sqrtf(170.0f);
+    *(llr++)   = SCALE_BYTE_CONV_QAM256 * real;
+    *(llr++)   = SCALE_BYTE_CONV_QAM256 * imag;
   }
 }
 
 void demod_256qam_lte_s(const cf_t* symbols, short* llr, int nsymbols)
 {
   for (int i = 0; i < nsymbols; i++) {
-    float real = SCALE_SHORT_CONV_QAM256 * crealf(symbols[i]);
-    float imag = SCALE_SHORT_CONV_QAM256 * cimagf(symbols[i]);
-
-    llr[8 * i + 0] = -real;
-    llr[8 * i + 1] = -imag;
-    llr[8 * i + 2] = fabsf(real) - SCALE_SHORT_CONV_QAM256 * 8 / sqrt(170);
-    llr[8 * i + 3] = fabsf(imag) - SCALE_SHORT_CONV_QAM256 * 8 / sqrt(170);
-    llr[8 * i + 4] = fabsf(llr[8 * i + 2]) - SCALE_SHORT_CONV_QAM256 * 4 / sqrt(170);
-    llr[8 * i + 5] = fabsf(llr[8 * i + 3]) - SCALE_SHORT_CONV_QAM256 * 4 / sqrt(170);
-    llr[8 * i + 6] = fabsf(llr[8 * i + 4]) - SCALE_SHORT_CONV_QAM256 * 2 / sqrt(170);
-    llr[8 * i + 7] = fabsf(llr[8 * i + 5]) - SCALE_SHORT_CONV_QAM256 * 2 / sqrt(170);
+    float real = -__real__ symbols[i];
+    float imag = -__imag__ symbols[i];
+    *(llr++)   = SCALE_SHORT_CONV_QAM256 * real;
+    *(llr++)   = SCALE_SHORT_CONV_QAM256 * imag;
+    real       = fabsf(real) - 8.0f / sqrtf(170.0f);
+    imag       = fabsf(imag) - 8.0f / sqrtf(170.0f);
+    *(llr++)   = SCALE_SHORT_CONV_QAM256 * real;
+    *(llr++)   = SCALE_SHORT_CONV_QAM256 * imag;
+    real       = fabsf(real) - 4.0f / sqrtf(170.0f);
+    imag       = fabsf(imag) - 4.0f / sqrtf(170.0f);
+    *(llr++)   = SCALE_SHORT_CONV_QAM256 * real;
+    *(llr++)   = SCALE_SHORT_CONV_QAM256 * imag;
+    real       = fabsf(real) - 2.0f / sqrtf(170.0f);
+    imag       = fabsf(imag) - 2.0f / sqrtf(170.0f);
+    *(llr++)   = SCALE_SHORT_CONV_QAM256 * real;
+    *(llr++)   = SCALE_SHORT_CONV_QAM256 * imag;
   }
 }
 
diff --git a/lib/src/phy/modem/test/modem_test.c b/lib/src/phy/modem/test/modem_test.c
index ed2b8efb2..553b39918 100644
--- a/lib/src/phy/modem/test/modem_test.c
+++ b/lib/src/phy/modem/test/modem_test.c
@@ -82,11 +82,12 @@ void parse_args(int argc, char **argv) {
 
 
 int main(int argc, char **argv) {
+  int                  ret = SRSLTE_SUCCESS;
   int i;
   srslte_modem_table_t mod;
   uint8_t *input, *input_bytes, *output;
   cf_t *symbols, *symbols_bytes;
-  float *llr, *llr2;
+  float*               llr;
 
   parse_args(argc, argv);
 
@@ -137,12 +138,6 @@ int main(int argc, char **argv) {
     exit(-1);
   }
 
-  llr2 = srslte_vec_malloc(sizeof(float) * num_bits);
-  if (!llr2) {
-    perror("malloc");
-    exit(-1);
-  }
-
   /* generate random data */
   for (i=0;i<num_bits;i++) {
     input[i] = rand()%2;
@@ -177,26 +172,27 @@ int main(int argc, char **argv) {
       exit(-1);
     }
   }
-  printf("Symbols OK\n");  
+
+  bzero(llr, sizeof(float) * num_bits / mod.nbits_x_symbol);
+
+  printf("Symbols OK\n");
   /* demodulate */
   gettimeofday(&x, NULL);
   srslte_demod_soft_demodulate(modulation, symbols, llr, num_bits / mod.nbits_x_symbol);
   gettimeofday(&y, NULL);
-  
   printf("\nElapsed time [us]: %ld\n", y.tv_usec - x.tv_usec);
   for (i=0;i<num_bits;i++) {
     output[i] = llr[i]>=0 ? 1 : 0;
   }
 
   /* check errors */
-  for (i=0;i<num_bits;i++) {
+  for (i = 0; i < num_bits && ret == SRSLTE_SUCCESS; i++) {
     if (input[i] != output[i]) {
       ERROR("Error in bit %d\n", i);
-      exit(-1);
+      ret = SRSLTE_ERROR;
     }
   }
 
-  free(llr2);
   free(llr);
   free(symbols);
   free(symbols_bytes);
@@ -206,6 +202,5 @@ int main(int argc, char **argv) {
 
   srslte_modem_table_free(&mod);
 
-  printf("Ok\n");
-  exit(0);
+  exit(ret);
 }