feat(sointu): update synth instead of recompiling if no commands (units) change

this avoids the nasty clicking resulting from complete reset / recompilation of the synth, which was the previous case

bridge/bridge.go

@@ -92,6 +92,50 @@ func (s *C.Synth) Release(voice int) {
 	s.SynthWrk.Voices[voice].Release = 1
 }
 
+// Update
+func (s *C.Synth) Update(patch sointu.Patch) error {
+	comPatch, err := compiler.Encode(&patch, compiler.AllFeatures{})
+	if err != nil {
+		return fmt.Errorf("error compiling patch: %v", err)
+	}
+	if len(comPatch.Commands) > 2048 { // TODO: 2048 could probably be pulled automatically from cgo
+		return errors.New("bridge supports at most 2048 commands; the compiled patch has more")
+	}
+	if len(comPatch.Values) > 16384 { // TODO: 16384 could probably be pulled automatically from cgo
+		return errors.New("bridge supports at most 16384 values; the compiled patch has more")
+	}
+	needsRefresh := false
+	for i, v := range comPatch.Commands {
+		if cmdChar := (C.uchar)(v); s.Commands[i] != cmdChar {
+			s.Commands[i] = cmdChar
+			needsRefresh = true // if any of the commands change, we retrigger all units
+		}
+	}
+	for i, v := range comPatch.Values {
+		s.Values[i] = (C.uchar)(v)
+	}
+	for i, v := range comPatch.DelayTimes {
+		s.DelayTimes[i] = (C.ushort)(v)
+	}
+	for i, v := range comPatch.SampleOffsets {
+		s.SampleOffsets[i].Start = (C.uint)(v.Start)
+		s.SampleOffsets[i].LoopStart = (C.ushort)(v.LoopStart)
+		s.SampleOffsets[i].LoopLength = (C.ushort)(v.LoopLength)
+	}
+	s.NumVoices = C.uint(comPatch.NumVoices)
+	s.Polyphony = C.uint(comPatch.PolyphonyBitmask)
+	if needsRefresh {
+		for i := range s.SynthWrk.Voices {
+			// if any of the commands change, we retrigger all units
+			// note that we don't change the notes or release states, just the units
+			for j := range s.SynthWrk.Voices[i].Units {
+				s.SynthWrk.Voices[i].Units[j] = C.Unit{}
+			}
+		}
+	}
+	return nil
+}
+
 // Render error stores the exact errorcode, which is actually just the x87 FPU flags,
 // with only the critical failure flags masked. Useful if you are interested exactly
 // what went wrong with the patch.

sointu.go

@@ -104,6 +104,7 @@ func (t *Track) Copy() Track {
 
 type Synth interface {
 	Render(buffer []float32, maxtime int) (int, int, error)
+	Update(patch Patch) error
 	Trigger(voice int, note byte)
 	Release(voice int)
 }

tracker/sequencer.go

@@ -88,11 +88,12 @@ func (s *Sequencer) ReadAudio(buffer []float32) (int, error) {
 	return totalRendered * 2, fmt.Errorf("despite %v attempts, Sequencer.ReadAudio could not fill the buffer (rowLength was %v, should be >> 0)", SEQUENCER_MAX_READ_TRIES, s.rowLength)
 }
 
-// Sets the synth used by the sequencer. This takes ownership of the synth: the
+// Updates the patch of the synth
-// synth should not be called by anyone else than the sequencer afterwards
+func (s *Sequencer) SetPatch(patch sointu.Patch) {
-func (s *Sequencer) SetSynth(synth sointu.Synth) {
 	s.mutex.Lock()
-	s.synth = synth
+	if s.synth != nil {
+		s.synth.Update(patch)
+	} // TODO: what is s.synth is nil?
 	s.mutex.Unlock()
 }
 

tracker/tracker.go

@@ -69,17 +69,11 @@ func (t *Tracker) LoadSong(song sointu.Song) error {
 	t.songPlayMutex.Lock()
 	defer t.songPlayMutex.Unlock()
 	t.song = song
-	if synth, err := bridge.Synth(song.Patch); err != nil {
-		fmt.Printf("error loading synth: %v\n", err)
-		t.synth = nil
-	} else {
-		t.synth = synth
-	}
 	t.PlayPosition.Clamp(song)
 	t.Cursor.Clamp(song)
 	t.SelectionCorner.Clamp(song)
 	if t.sequencer != nil {
-		t.sequencer.SetSynth(t.synth)
+		t.sequencer.SetPatch(song.Patch)
 	}
 	return nil
 }
@@ -213,12 +207,7 @@ func (t *Tracker) AddInstrument() {
 			Units:     units,
 		})
 	}
-	synth, err := bridge.Synth(t.song.Patch)
+	t.sequencer.SetPatch(t.song.Patch)
-	if err == nil {
-		t.sequencer.SetSynth(synth)
-	} else {
-		fmt.Printf("%v", err)
-	}
 }
 
 // SetCurrentNote sets the (note) value in current pattern under cursor to iv