Next test.

effect_modulated_delay.cpp

@@ -107,6 +107,7 @@ void AudioEffectModulatedDelay::update(void)
   if (block && modulation)
   {
     int16_t *bp;
+    int16_t cb_mod_index_neighbor;
     float *mp;
     float mod_index;
     float mod_number;
@@ -130,11 +131,31 @@ void AudioEffectModulatedDelay::update(void)
       mod_fraction = modff(mod_index, &mod_number); // split float of mod_index into integer (= mod_number) and fraction part
 
       // calculate modulation index into circular buffer
-      cb_mod_index = (_cb_index - (_delay_offset + int(mod_index))) % _delay_length;
+      cb_mod_index = (_cb_index - (_delay_offset + int(mod_index)));
+      if (cb_mod_index >= _delay_length)
+        cb_mod_index -= _delay_length;
       if (cb_mod_index < 0) // check for negative offsets and correct them
         cb_mod_index += _delay_length;
 
-      *bp = round(float(_delayline[cb_mod_index]) * mod_fraction + float(_delayline[cb_mod_index + 1]) * (1.0 - mod_fraction));
+      if (*mp < 0.0)
+      {
+        if (cb_mod_index == 0)
+          cb_mod_index_neighbor = _delay_length;
+        else
+          cb_mod_index_neighbor = cb_mod_index - 1;
+      }
+      else
+      {
+        if (cb_mod_index == _delay_length)
+          cb_mod_index_neighbor = 0;
+        else
+          cb_mod_index_neighbor = cb_mod_index + 1;
+      }
+
+      if (*mp < 0.0)
+        *bp = round(float(_delayline[cb_mod_index]) * mod_fraction + float(_delayline[cb_mod_index_neighbor]) * (1.0 - mod_fraction));
+      else
+        *bp = round(float(_delayline[cb_mod_index_neighbor]) * mod_fraction + float(_delayline[cb_mod_index]) * (1.0 - mod_fraction));
 
       // push the pointers forward
       bp++; // next audio data