sound system refactored

chip8/chip8.go

@@ -4,10 +4,11 @@ import (
 	_ "embed"
 	"encoding/binary"
 	"image"
+	"math"
 )
 
-//go:embed sound.wav
-var Sound []byte
+//go:embed beep.wav
+var Beep []byte
 
 const (
 	MemorySize      = 4096 // 4KB of memory
@@ -22,10 +23,11 @@ const (
 	Width      = 64
 	Height     = 32
 	FPS        = 60
+	SampleRate = 44100
 )
 
 type KeyPressed func(key uint8) bool
-type PlaySound func(sound []byte) func()
+type SoundPlayer func(sound []byte) (func(), func())
 
 type ROM struct {
 	Name string
@@ -43,14 +45,14 @@ type Emulator struct {
 	ROM        ROM               // game rom
 	Display    *image.RGBA       // display buffer
 	KeyPressed KeyPressed        // input function
-	PlaySound  PlaySound
-	StopSound  func()
+	PlaySound  func()            // play sound effect
+	StopSound  func()            // stop sound effect
 }
 
-func NewEmulator(keyPressed KeyPressed, playSound PlaySound) *Emulator {
+func NewEmulator(keyPressed KeyPressed, soundPlayer SoundPlayer) *Emulator {
 	emulator := new(Emulator)
 	emulator.KeyPressed = keyPressed
-	emulator.PlaySound = playSound
+	emulator.PlaySound, emulator.StopSound = soundPlayer(Beep)
 	emulator.Stack = NewStack()
 	emulator.Display = image.NewRGBA(image.Rect(0, 0, Width, Height))
 	emulator.Reset()
@@ -97,20 +99,13 @@ func (emulator *Emulator) LoadFont() {
 }
 
 func (emulator *Emulator) UpdateTimers() {
-	if emulator.DT > 0 {
-		emulator.DT -= 1
-	}
-	if emulator.ST > 0 {
-		emulator.ST -= 1
-		if emulator.StopSound == nil {
-			emulator.StopSound = emulator.PlaySound(Sound)
-		}
+	if emulator.ST != 0 {
+		emulator.PlaySound()
 	} else {
-		if emulator.StopSound != nil {
 		emulator.StopSound()
-			emulator.StopSound = nil
-		}
 	}
+	emulator.ST = uint8(math.Max(0, float64(emulator.ST)-1))
+	emulator.DT = uint8(math.Max(0, float64(emulator.DT)-1))
 }
 
 func (emulator *Emulator) Cycle() {

chip8/chip8_test.go

@@ -8,7 +8,9 @@ import (
 )
 
 func TestEmulator_Reset(t *testing.T) {
-	emulator := chip8.NewEmulator(nil, nil)
+	soundPlayer := func(sound []byte) (func(), func()) { return nil, nil }
+
+	emulator := chip8.NewEmulator(nil, soundPlayer)
 	emulator.V[0x03] = 0xFF
 	emulator.V[0x0F] = 0xBB
 

main.go

@@ -50,71 +50,81 @@ var KeyMapping = []ebiten.Key{
 	ebiten.KeyV,
 }
 
-type UI struct {
-	Emulator     *chip8.Emulator
+type GUI struct {
 	State    State
-	AudioContext *audio.Context
+	Emulator *chip8.Emulator
 }
 
-func (ui *UI) Run() {
+func (gui *GUI) Run() {
 	for {
-		ui.Emulator.Cycle()
+		gui.Emulator.Cycle()
 		time.Sleep(time.Millisecond * 2)
 	}
 }
 
-func (ui *UI) Update() error {
+func (gui *GUI) Update() error {
 	if ebiten.IsKeyPressed(ebiten.KeyEscape) {
-		ui.Emulator.Reset()
+		gui.Emulator.Reset()
 	}
-
-	switch ui.State {
+	switch gui.State {
 	case LoadingState:
-		go ui.Run()
-		ui.State = RunningState
+		go gui.Run()
+		gui.State = RunningState
 	case RunningState:
-		ui.Emulator.UpdateTimers()
+		gui.Emulator.UpdateTimers()
 	}
 	return nil
 }
 
-func (ui *UI) Draw(screen *ebiten.Image) {
-	frame := ebiten.NewImageFromImage(ui.Emulator.Display)
-
+func (gui *GUI) Draw(screen *ebiten.Image) {
+	frame := ebiten.NewImageFromImage(gui.Emulator.Display)
 	operation := new(ebiten.DrawImageOptions)
 	operation.GeoM.Scale(ScreenScale, ScreenScale)
-
 	screen.DrawImage(frame, operation)
 }
 
-func (ui *UI) Layout(int, int) (int, int) {
+func (gui *GUI) Layout(int, int) (int, int) {
 	return Width, Height
 }
 
-func (ui *UI) KeyPressed(key uint8) bool {
+func KeyPressed(key uint8) bool {
 	return ebiten.IsKeyPressed(KeyMapping[key])
 }
 
-func (ui *UI) PlaySound(sound []byte) func() {
-	player := ui.AudioContext.NewPlayerFromBytes(sound)
+func SoundPlayer(sound []byte) (func(), func()) {
+	player := audio.NewContext(chip8.SampleRate).NewPlayerFromBytes(sound)
 	player.SetVolume(0.3)
+	return PlaySound(player), StopSound(player)
+}
+
+func PlaySound(player *audio.Player) func() {
+	return func() {
+		if player.IsPlaying() {
+			return
+		}
 		player.Play()
-	return func() { _ = player.Close() }
+	}
+}
+
+func StopSound(player *audio.Player) func() {
+	return func() {
+		player.Pause()
+		player.Seek(0)
+	}
 }
 
 func main() {
 	rom := LoadROM()
 
-	ui := UI{}
-	ui.Emulator = chip8.NewEmulator(ui.KeyPressed, ui.PlaySound)
-	ui.State = LoadingState
-	ui.AudioContext = audio.NewContext(44100)
-	ui.Emulator.LoadROM(rom)
+	gui := GUI{}
+	gui.State = LoadingState
+	gui.Emulator = chip8.NewEmulator(KeyPressed, SoundPlayer)
+	gui.Emulator.LoadROM(rom)
 
 	ebiten.SetWindowSize(Width, Height)
 	ebiten.SetWindowTitle("CHIP-8 : " + rom.Name)
 
-	if err := ebiten.RunGame(&ui); err != nil {
+	if err := ebiten.RunGame(&gui); err != nil {
 		log.Fatal(err)
 	}
 }