From: okcsampson <okcsampson@01035d8c-6547-0410-b346-abe4f91aad63>
Date: Sat, 31 Mar 2018 17:44:56 +0000 (+0000)
Subject: Update carrier table generation
X-Git-Url: http://git.whiteaudio.com/gitweb/?a=commitdiff_plain;h=b096ac044b30996c49a103b371b540cb17460214;p=freetel-svn-tracking.git

Update carrier table generation

git-svn-id: https://svn.code.sf.net/p/freetel/code@3443 01035d8c-6547-0410-b346-abe4f91aad63
---

diff --git a/codec2-dev/src/ofdm.c b/codec2-dev/src/ofdm.c
index 3631f982..e47b18ed 100644
--- a/codec2-dev/src/ofdm.c
+++ b/codec2-dev/src/ofdm.c
@@ -307,15 +307,20 @@ static void ofdm_txframe(struct OFDM *ofdm, complex float tx[OFDM_SAMPLESPERFRAM
  * Return NULL on fail
  */
 
-struct OFDM *ofdm_create(const struct OFDM_CONFIG * config) {
+struct OFDM *ofdm_create(const struct OFDM_CONFIG *config) {
     struct OFDM *ofdm;
-    int i, j;
+    int i, j, n;
 
     if ((ofdm = (struct OFDM *) malloc(sizeof (struct OFDM))) == NULL) {
         return NULL;
     }
 
     /* Copy config structure */
+
+    if (config == NULL) { /* prevent segmentation error */
+        return NULL;
+    }
+
     memcpy((void*)&ofdm->config,(void*)config,sizeof(struct OFDM_CONFIG));
 
     /* store complex BPSK pilot symbols */
@@ -326,20 +331,14 @@ struct OFDM *ofdm_create(const struct OFDM_CONFIG * config) {
 
     /* carrier tables for up and down conversion */
 
-    int Nlower = floorf((OFDM_CENTRE - OFDM_RS * (OFDM_NC / 2)) / OFDM_RS);
+    float lower = OFDM_CENTRE - OFDM_RS * (OFDM_NC / 2);
+    int Nlower = floorf(lower / OFDM_RS);
 
-    for (i = 0, j = Nlower; i < (OFDM_NC + 2); i++, j++) {
-        /*
-         * 2 * pi * j/144  j=19..36
-         * j = 1 kHz to 2 kHz (1.5 kHz center)
-         */
-
-        ofdm->w[i] = TAU * (float) j / (OFDM_FS / OFDM_RS);
-    }
+    for (i = 0, n = Nlower; i < (OFDM_NC + 2); i++, n++) {
+        float w = (TAU * (float) n) / (OFDM_FS / OFDM_RS);
 
-    for (i = 0; i < (OFDM_NC + 2); i++) {
         for (j = 0; j < OFDM_M; j++) {
-            ofdm->W[i][j] = cexpf(I * ofdm->w[i] * j);
+            ofdm->W[i][j] = cexpf(I * w * j);
         }
     }
 
diff --git a/codec2-dev/src/ofdm_internal.h b/codec2-dev/src/ofdm_internal.h
index 162cf334..5d37a322 100644
--- a/codec2-dev/src/ofdm_internal.h
+++ b/codec2-dev/src/ofdm_internal.h
@@ -106,7 +106,6 @@ struct OFDM {
     complex float W[OFDM_NC + 2][OFDM_M];
     complex float rxbuf[OFDM_RXBUF];
     complex float pilots[OFDM_NC + 2];
-    float w[OFDM_NC + 2];
     
     /* Demodulator data */