Add way to stop looping sound

Sfx(-2,...) stops the loop. Sound effect will be played to the end but will not repeat.

audio/audio.go

@@ -96,7 +96,7 @@ const (
 	Channel1    Channel = 1
 	Channel2    Channel = 2
 	Channel3    Channel = 3
-	ChannelAny  Channel = -1
+	ChannelAny  Channel = -1 // Rename - it means all channels for Sfx(-2, ...)
 	ChannelStop Channel = -2
 )
 

audio/synth.go

@@ -75,7 +75,7 @@ func (c *channel) moveToNextNote(sfx SoundEffect) {
 	c.notesToGo--
 	c.noteNo++
 
-	if c.noteNo == int(sfx.LoopStop) {
+	if c.noteNo == int(sfx.LoopStop) && !c.loopingDisabled {
 		c.noteNo = int(sfx.LoopStart)
 	}
 
@@ -96,6 +96,11 @@ func (c *channel) moveToNextNote(sfx SoundEffect) {
 func (s *Synthesizer) Sfx(sfxNo int, ch Channel, offset, length int) {
 	fmt.Println("Sfx is not implemented yet. Sorry...")
 
+	if sfxNo == -2 {
+		s.disableLooping(ch)
+		return
+	}
+
 	if ch >= ChannelStop && ch <= Channel3 {
 		s.stopSfx(sfxNo)
 	}
@@ -131,6 +136,19 @@ func (s *Synthesizer) Sfx(sfxNo int, ch Channel, offset, length int) {
 	s.channels[ch].oscillator.FreqHz = pitchToFreq(note0.Pitch)
 }
 
+func (s *Synthesizer) disableLooping(ch Channel) {
+	if ch == ChannelAny || ch == ChannelStop {
+		for i := range s.channels {
+			s.channels[i].loopingDisabled = true
+		}
+		return
+	}
+
+	if ch >= Channel0 && ch <= Channel3 {
+		s.channels[ch].loopingDisabled = true
+	}
+}
+
 func (s *Synthesizer) stopSfx(no int) {
 	for i, c := range s.channels {
 		if c.playing && c.sfxNo == no {
@@ -364,11 +382,12 @@ func boolToByte(b bool) byte {
 }
 
 type channel struct {
-	sfxNo        int
-	noteNo       int
-	notesToGo    int
-	frame        int
-	noteEndFrame int
-	oscillator   internal.Oscillator
-	playing      bool
+	sfxNo           int
+	noteNo          int
+	notesToGo       int
+	frame           int
+	noteEndFrame    int
+	oscillator      internal.Oscillator
+	playing         bool
+	loopingDisabled bool
 }

audio/synth_test.go

@@ -564,7 +564,6 @@ func TestSynthesizer_Sfx(t *testing.T) {
 				assertNotSilence(t, readSamples(synth, durationOfNoteWhenSpeedIsOne))
 			})
 		}
-
 	})
 
 	sfxOffsetLengthTest(t)
@@ -820,6 +819,77 @@ func sfxLoopTest(t *testing.T) {
 			})
 		}
 	})
+
+	t.Run("should stop the loop on given channel", func(t *testing.T) {
+		channels := []audio.Channel{audio.Channel0, audio.Channel1, audio.Channel2, audio.Channel3}
+
+		for _, ch := range channels {
+			testName := fmt.Sprintf("%d", ch)
+
+			t.Run(testName, func(t *testing.T) {
+				var e audio.SoundEffect
+				e.Notes[0].Volume = audio.VolumeLoudest
+				e.Speed = 1
+				e.LoopStart = 0
+				e.LoopStop = 1
+
+				synth := &audio.Synthesizer{}
+				synth.SetSfx(0, e)
+
+				synth.Sfx(0, ch, 0, 32)
+				// when
+				synth.Sfx(-2, ch, 0, 0)
+				// then
+				assertNotSilence(t, readSamples(synth, durationOfNoteWhenSpeedIsOne)) // wait until entire sfx is played
+				assertSilence(t, readSamples(synth, durationOfNoteWhenSpeedIsOne))    // wait until entire sfx is played
+			})
+		}
+	})
+
+	t.Run("should stop the loop on all channels", func(t *testing.T) {
+		channels := []audio.Channel{audio.ChannelAny, audio.ChannelStop}
+
+		for _, ch := range channels {
+			testName := fmt.Sprintf("%d", ch)
+
+			t.Run(testName, func(t *testing.T) {
+				var e audio.SoundEffect
+				e.Notes[0].Volume = audio.VolumeLoudest
+				e.Speed = 1
+				e.LoopStart = 0
+				e.LoopStop = 1
+
+				synth := &audio.Synthesizer{}
+				synth.SetSfx(0, e)
+
+				synth.Sfx(0, audio.Channel0, 0, 32)
+				synth.Sfx(0, audio.Channel1, 0, 32)
+				synth.Sfx(0, audio.Channel2, 0, 32)
+				synth.Sfx(0, audio.Channel3, 0, 32)
+				// when
+				synth.Sfx(-2, ch, 0, 0)
+				// then
+				assertNotSilence(t, readSamples(synth, durationOfNoteWhenSpeedIsOne)) // wait until entire sfx is played
+				assertSilence(t, readSamples(synth, durationOfNoteWhenSpeedIsOne))    // wait until entire sfx is played
+			})
+		}
+	})
+
+	t.Run("should not panic when trying to stop the loop with invalid channel", func(t *testing.T) {
+		channels := []audio.Channel{-3, 4}
+
+		for _, ch := range channels {
+			testName := fmt.Sprintf("%d", ch)
+
+			t.Run(testName, func(t *testing.T) {
+				synth := &audio.Synthesizer{}
+
+				assert.NotPanics(t, func() {
+					synth.Sfx(-2, ch, 0, 0)
+				})
+			})
+		}
+	})
 }
 
 func sfxLengthTest(t *testing.T) {