Cope with zero-duration effects (#11)

* Cope with zero-duration effects. Closes microbit-foundation/codal-microbit#149 * Use same code path for zero and positive duration
lancaster-university · Nov 2, 2020 · bea9f66 · bea9f66
1 parent b040865
commit bea9f66
Show file tree

Hide file tree

Showing 2 changed files with 15 additions and 11 deletions.
diff --git a/inc/SoundEmojiSynthesizer.h b/inc/SoundEmojiSynthesizer.h
@@ -163,8 +163,9 @@ namespace codal
 
         /**
          * Schedules the next sound effect as defined in the effectBuffer, if available.
+         * @return true if we've just completed a buffer of effects, false otherwise.
          */
-        void nextSoundEffect();
+        bool nextSoundEffect();
 
         /**
         * Schedules playout of the given sound effect.

diff --git a/source/SoundEmojiSynthesizer.cpp b/source/SoundEmojiSynthesizer.cpp
@@ -133,9 +133,17 @@ void SoundEmojiSynthesizer::stop() {
 
 /**
  * Schedules the next sound effect as defined in the effectBuffer, if available.
+ * @return true if we've just completed a buffer of effects, false otherwise.
  */
-void SoundEmojiSynthesizer::nextSoundEffect()
+bool SoundEmojiSynthesizer::nextSoundEffect()
 {
+    const bool hadEffect = effect != NULL;
+    if (status & EMOJI_SYNTHESIZER_STATUS_STOPPING)
+    {
+        effect = NULL;
+        effectBuffer = emptyBuffer;
+    }
+
     // If a sequence of SoundEffects are being played, attempt to move on to the next.
     // If not, select the first in the buffer.
     if (effect)
@@ -149,14 +157,14 @@ void SoundEmojiSynthesizer::nextSoundEffect()
         // if we have an effect with a negative duration, reset the buffer (unless there is an update pending)
         effect = (SoundEffect *) &effectBuffer[0];
 
-        if (effect->duration > 0 || lock.getWaitCount() > 0)
+        if (effect->duration >= 0 || lock.getWaitCount() > 0)
         {
             effect = NULL;
             effectBuffer = emptyBuffer;
             samplesWritten = 0;
             samplesToWrite = 0;
             position = 0.0f;
-            return;
+            return hadEffect;
         }
     }
 
@@ -173,6 +181,7 @@ void SoundEmojiSynthesizer::nextSoundEffect()
         effect->effects[i].steps = max(effect->effects[i].steps, 1);
         samplesPerStep[i] = (float) samplesToWrite / (float) effect->effects[i].steps;
     }
+    return false;
 }
 
 /**
@@ -190,13 +199,7 @@ ManagedBuffer SoundEmojiSynthesizer::pull()
     {
         if (samplesWritten == samplesToWrite || status & EMOJI_SYNTHESIZER_STATUS_STOPPING)
         {
-            bool renderComplete = samplesWritten > 0;
-            if (status & EMOJI_SYNTHESIZER_STATUS_STOPPING)
-            {
-                effect = NULL;
-                effectBuffer = emptyBuffer;
-            }
-            nextSoundEffect();
+            bool renderComplete = nextSoundEffect();
 
             // If we have just completed active playout of an effect, and there are no more effects scheduled, 
             // unblock any fibers that may be waiting to play a sound effect.