emulator finally working 🥳

chip8/chip8.go

@@ -3,12 +3,11 @@ package chip8
 import (
 	"encoding/binary"
 	"image"
-	"math"
 )
 
 const (
 	MemorySize      = 4096 // 4KB of memory
-	InstructionSize = 2
+	InstructionSize = 2    // 2 bytes long instructions
 )
 
 const (
@@ -21,22 +20,31 @@ const (
 	FPS    = 60
 )
 
-type Emulator struct {
-	V       [16]uint8         // general registers
-	I       uint16            // address register
-	PC      uint16            // program counter
-	DT      uint8             // delay timer
-	ST      uint8             // sound timer
-	Stack   *Stack            // very simple stack
-	Memory  [MemorySize]uint8 // 4KB of system RAM
-	ROM     []uint8           // game rom
-	Display *image.Gray       // display buffer
+type KeyPressed func(key uint8) bool
+
+type ROM struct {
+	Name string
+	Data []byte
 }
 
-func NewEmulator() *Emulator {
+type Emulator struct {
+	V          [16]uint8         // general registers
+	I          uint16            // address register
+	PC         uint16            // program counter
+	DT         uint8             // delay timer
+	ST         uint8             // sound timer
+	Stack      *Stack            // very simple stack
+	Memory     [MemorySize]uint8 // 4KB of system RAM
+	ROM        ROM               // game rom
+	Display    *image.RGBA       // display buffer
+	KeyPressed KeyPressed        // input function
+}
+
+func NewEmulator(keyPressed KeyPressed) *Emulator {
 	emulator := new(Emulator)
+	emulator.KeyPressed = keyPressed
 	emulator.Stack = NewStack()
-	emulator.Display = image.NewGray(image.Rect(0, 0, Width, Height))
+	emulator.Display = image.NewRGBA(image.Rect(0, 0, Width, Height))
 	emulator.Reset()
 	return emulator
 }
@@ -54,10 +62,9 @@ func (emulator *Emulator) Reset() {
 	emulator.LoadFont()
 }
 
-func (emulator *Emulator) LoadROM(rom []uint8) {
+func (emulator *Emulator) LoadROM(rom ROM) {
 	emulator.ROM = rom
-	// load rom on memory
-	copy(emulator.Memory[ProgramAddress:], emulator.ROM)
+	copy(emulator.Memory[ProgramAddress:], emulator.ROM.Data)
 }
 
 func (emulator *Emulator) LoadFont() {
@@ -81,11 +88,18 @@ func (emulator *Emulator) LoadFont() {
 	})
 }
 
-func (emulator *Emulator) Cycle() {
-	emulator.DT = uint8(math.Max(0, float64(emulator.DT)-1))
-	emulator.ST = uint8(math.Max(0, float64(emulator.ST)-1))
+func (emulator *Emulator) UpdateTimers() {
+	if emulator.DT > 0 {
+		emulator.DT -= 1
+	}
+	if emulator.ST > 0 {
+		emulator.ST -= 1
+	}
+}
 
+func (emulator *Emulator) Cycle() {
 	instruction := binary.BigEndian.Uint16(emulator.Memory[emulator.PC:])
+	emulator.PC += InstructionSize
 
 	nnn := instruction & 0x0FFF
 	n := uint8(instruction & 0x000F)
@@ -93,20 +107,18 @@ func (emulator *Emulator) Cycle() {
 	x := uint8(instruction & 0x0F00 >> 8)
 	y := uint8(instruction & 0x00F0 >> 4)
 
-	switch instruction & 0xF000 >> 12 {
+	switch instruction >> 12 & 0xF {
 	case 0x0:
-		switch instruction & 0x00FF {
-		case 0xE0: // 00E0 - CLS
+		switch instruction {
+		case 0x00E0: // 00E0 - CLS
 			emulator.ClearScreen()
-		case 0xEE: // 00EE - RET
+		case 0x00EE: // 00EE - RET
 			emulator.Return()
 		}
 	case 0x1: // 1nnn - JP addr
 		emulator.Jump(nnn)
-		return // skip PC increment
 	case 0x2: // 2nnn - CALL addr
 		emulator.Call(nnn)
-		return // skip PC increment
 	case 0x3: // 3xkk - SE Vx, byte
 		emulator.SkipEqualByte(x, kk)
 	case 0x4: // 4xkk - SNE Vx, byte
@@ -177,6 +189,4 @@ func (emulator *Emulator) Cycle() {
 			emulator.ReadRegisters(x)
 		}
 	}
-
-	emulator.PC += InstructionSize
 }

chip8/chip8_test.go

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

chip8/instructions.go

@@ -4,7 +4,6 @@ import (
 	"image"
 	"image/color"
 	"image/draw"
-	_ "image/png"
 	"math/rand"
 )
 
@@ -125,7 +124,6 @@ func (emulator *Emulator) Add(x uint8, y uint8) {
 	emulator.V[0xF] = uint8(sum >> 8)
 }
 
-// SUB Vx, Vy
 // Set Vx = Vx - Vy, set VF = NOT borrow.
 //
 // If Vx > Vy, then VF is set to 1, otherwise 0.
@@ -140,7 +138,7 @@ func (emulator *Emulator) Sub(x uint8, y uint8) {
 // If the least-significant bit of Vx is 1, then VF is set to 1, otherwise 0.
 // Then Vx is divided by 2.
 func (emulator *Emulator) ShiftRight(x uint8) {
-	emulator.V[0xF] = emulator.V[x] & 0b0000_0001
+	emulator.V[0xF] = emulator.V[x] & 0b00000001
 	emulator.V[x] >>= 1
 }
 
@@ -158,7 +156,7 @@ func (emulator *Emulator) SubN(x uint8, y uint8) {
 // If the most-significant bit of Vx is 1, then VF is set to 1, otherwise to 0.
 // Then Vx is multiplied by 2.
 func (emulator *Emulator) ShiftLeft(x uint8) {
-	emulator.V[0xF] = emulator.V[x] & 0b1000_0000
+	emulator.V[0xF] = (emulator.V[x] & 0b10000000) >> 7
 	emulator.V[x] <<= 1
 }
 
@@ -202,29 +200,27 @@ func (emulator *Emulator) Random(x uint8, kk uint8) {
 // VF is set to 1, otherwise it is set to 0. If the sprite is positioned so part of it
 // is outside the coordinates of the display, it wraps around to the opposite side of the screen.
 func (emulator *Emulator) Draw(x uint8, y uint8, n uint8) {
+	x = emulator.V[x]
+	y = emulator.V[y]
 	width := uint8(8)
 	height := n
 
 	emulator.V[0xF] = 0x00 // clean collision flag
 
-	for row := uint8(0); row < height; row += 1 {
-		sprite := emulator.Memory[emulator.I+uint16(row)]
+	for yline := uint8(0); yline < height; yline++ {
+		sprite := emulator.Memory[emulator.I+uint16(yline)]
 
-		for col := uint8(0); col < width; col += 1 {
-			if (sprite & 0b10000000) == 0b10000000 {
-				px, py := int(emulator.V[x]+col), int(emulator.V[y]+row)
+		for xline := uint8(0); xline < width; xline++ {
+			if (sprite & 0b10000000) != 0x00 {
+				px, py := int(x+xline)%Width, int(y+yline)%Height
+				color := emulator.Display.PixOffset(px, py) + 1 // color offset: 0:red, 1:green, 2:blue
 
-				// check for pixel collision
-				if emulator.Display.At(px, py) != color.Black {
-					emulator.V[0xF] = 0x01 // set collision flag
+				if emulator.Display.Pix[color] != 0x00 {
+					emulator.V[0xF] = 0x01 // collision
 				}
 
-				// draw pixel
-				emulator.Display.Set(px, py, color.White)
+				emulator.Display.Pix[color] ^= 0xFF
 			}
-
-			// shift the sprite left 1
-			// this will move the next next col/bit of the sprite into the first position
 			sprite <<= 1
 		}
 	}
@@ -235,7 +231,9 @@ func (emulator *Emulator) Draw(x uint8, y uint8, n uint8) {
 // Checks the keyboard, and if the key corresponding to the value of Vx
 // is currently in the down position, PC is increased by 2.
 func (emulator *Emulator) SkipKeyPressed(x uint8) {
-	// TODO: implement input
+	if emulator.KeyPressed(emulator.V[x]) {
+		emulator.PC += InstructionSize
+	}
 }
 
 // Skip next instruction if key with the value of Vx is not pressed.
@@ -243,7 +241,9 @@ func (emulator *Emulator) SkipKeyPressed(x uint8) {
 // Checks the keyboard, and if the key corresponding to the value of Vx
 // is currently in the up position, PC is increased by 2.
 func (emulator *Emulator) SkipKeyNotPressed(x uint8) {
-	// TODO: implement input
+	if !emulator.KeyPressed(emulator.V[x]) {
+		emulator.PC += InstructionSize
+	}
 }
 
 // Set Vx = delay timer value.
@@ -257,7 +257,14 @@ func (emulator *Emulator) ReadDT(x uint8) {
 //
 // All execution stops until a key is pressed, then the value of that key is stored in Vx.
 func (emulator *Emulator) ReadKey(x uint8) {
-	// TODO: implement input
+	for {
+		for key := uint8(0); key < 16; key++ {
+			if emulator.KeyPressed(key) {
+				emulator.V[x] = key
+				return
+			}
+		}
+	}
 }
 
 // Set delay timer = Vx.
@@ -286,7 +293,7 @@ func (emulator *Emulator) AddI(x uint8) {
 // The value of I is set to the location for the hexadecimal sprite
 // corresponding to the value of Vx.
 func (emulator *Emulator) SetI(x uint8) {
-	emulator.I += uint16(emulator.V[x]) * 5
+	emulator.I = uint16(emulator.V[x]) * 5
 }
 
 // Store BCD representation of Vx in memory locations I, I+1, and I+2.
@@ -303,16 +310,12 @@ func (emulator *Emulator) LoadBCD(x uint8) {
 //
 // The interpreter copies the values of registers V0 through Vx into memory, starting at the address in I.
 func (emulator *Emulator) StoreRegisters(x uint8) {
-	for i := uint8(0); i <= x; i++ {
-		emulator.Memory[emulator.I+uint16(i)] = emulator.V[i]
-	}
+	copy(emulator.Memory[emulator.I:], emulator.V[:x+1])
 }
 
 // Read registers V0 through Vx from memory starting at location I.
 //
 // The interpreter reads values from memory starting at location I into registers V0 through Vx.
 func (emulator *Emulator) ReadRegisters(x uint8) {
-	for i := uint8(0); i <= x; i++ {
-		emulator.V[i] = emulator.Memory[emulator.I+uint16(i)]
-	}
+	copy(emulator.V[0:], emulator.Memory[emulator.I:emulator.I+uint16(x)+1])
 }

cmd/chip8/main.go

@@ -1,57 +0,0 @@
-package main
-
-import (
-	"io/ioutil"
-	"log"
-	"os"
-
-	"github.com/hajimehoshi/ebiten"
-	"github.com/tangzero/chip8-emulator/chip8"
-)
-
-const (
-	ScreenScale = 20
-	Width       = chip8.Width * ScreenScale
-	Height      = chip8.Height * ScreenScale
-)
-
-type UI struct {
-	Emulator *chip8.Emulator
-}
-
-func (ui *UI) Update(screen *ebiten.Image) error {
-	ui.Emulator.Cycle()
-	return nil
-}
-
-func (ui *UI) Draw(screen *ebiten.Image) {
-	frame, err := ebiten.NewImageFromImage(ui.Emulator.Display, ebiten.FilterDefault)
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	op := new(ebiten.DrawImageOptions)
-	op.GeoM.Scale(ScreenScale, ScreenScale)
-
-	screen.DrawImage(frame, op)
-}
-
-func (ui *UI) Layout(outsideWidth, outsideHeight int) (int, int) {
-	return Width, Height
-}
-
-func main() {
-	rom, err := ioutil.ReadFile(os.Args[1])
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	ui := UI{Emulator: chip8.NewEmulator()}
-	ui.Emulator.LoadROM(rom)
-
-	ebiten.SetWindowSize(Width, Height)
-	ebiten.SetWindowTitle("CHIP 8")
-	if err := ebiten.RunGame(&ui); err != nil {
-		log.Fatal(err)
-	}
-}

go.mod

@@ -2,18 +2,22 @@ module github.com/tangzero/chip8-emulator
 
 go 1.17
 
+require (
+	github.com/hajimehoshi/ebiten/v2 v2.2.5
+	github.com/stretchr/testify v1.7.0
+)
+
 require (
 	github.com/davecgh/go-spew v1.1.0 // indirect
 	github.com/go-gl/glfw/v3.3/glfw v0.0.0-20210727001814-0db043d8d5be // indirect
-	github.com/hajimehoshi/ebiten v1.12.12 // indirect
-	github.com/hajimehoshi/ebiten/v2 v2.2.5 // indirect
 	github.com/jezek/xgb v0.0.0-20210312150743-0e0f116e1240 // indirect
+	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/stretchr/testify v1.7.0 // indirect
 	golang.org/x/exp v0.0.0-20190731235908-ec7cb31e5a56 // indirect
 	golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d // indirect
 	golang.org/x/mobile v0.0.0-20210902104108-5d9a33257ab5 // indirect
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
 	golang.org/x/sys v0.0.0-20210917161153-d61c044b1678 // indirect
+	gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b // indirect
 	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
 )

go.sum

@@ -1,34 +1,24 @@
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/go-gl/glfw/v3.3/glfw v0.0.0-20200707082815-5321531c36a2/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20210727001814-0db043d8d5be h1:vEIVIuBApEBQTEJt19GfhoU+zFSV+sNTa9E9FdnRYfk=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20210727001814-0db043d8d5be/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
-github.com/gofrs/flock v0.8.0/go.mod h1:F1TvTiK9OcQqauNUHlbJvyl9Qa1QvF/gOUDKA14jxHU=
-github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
-github.com/hajimehoshi/bitmapfont v1.3.0/go.mod h1:/Qb7yVjHYNUV4JdqNkPs6BSZwLjKqkZOMIp6jZD0KgE=
 github.com/hajimehoshi/bitmapfont/v2 v2.1.3/go.mod h1:2BnYrkTQGThpr/CY6LorYtt/zEPNzvE/ND69CRTaHMs=
-github.com/hajimehoshi/ebiten v1.12.12 h1:JvmF1bXRa+t+/CcLWxrJCRsdjs2GyBYBSiFAfIqDFlI=
-github.com/hajimehoshi/ebiten v1.12.12/go.mod h1:1XI25ImVCDPJiXox4h9yK/CvN5sjDYnbF4oZcFzPXHw=
 github.com/hajimehoshi/ebiten/v2 v2.2.5 h1:i6NdS6pEi5kgfTh+4XAVCVtCXxjTyxzU1cj1oqHWkZQ=
 github.com/hajimehoshi/ebiten/v2 v2.2.5/go.mod h1:olKl/qqhMBBAm2oI7Zy292nCtE+nitlmYKNF3UpbFn0=
-github.com/hajimehoshi/file2byteslice v0.0.0-20200812174855-0e5e8a80490e/go.mod h1:CqqAHp7Dk/AqQiwuhV1yT2334qbA/tFWQW0MD2dGqUE=
 github.com/hajimehoshi/file2byteslice v0.0.0-20210813153925-5340248a8f41/go.mod h1:CqqAHp7Dk/AqQiwuhV1yT2334qbA/tFWQW0MD2dGqUE=
-github.com/hajimehoshi/go-mp3 v0.3.1/go.mod h1:qMJj/CSDxx6CGHiZeCgbiq2DSUkbK0UbtXShQcnfyMM=
 github.com/hajimehoshi/go-mp3 v0.3.2/go.mod h1:qMJj/CSDxx6CGHiZeCgbiq2DSUkbK0UbtXShQcnfyMM=
 github.com/hajimehoshi/oto v0.6.1/go.mod h1:0QXGEkbuJRohbJaxr7ZQSxnju7hEhseiPx2hrh6raOI=
-github.com/hajimehoshi/oto v0.6.8/go.mod h1:0QXGEkbuJRohbJaxr7ZQSxnju7hEhseiPx2hrh6raOI=
 github.com/hajimehoshi/oto/v2 v2.1.0-alpha.2/go.mod h1:rUKQmwMkqmRxe+IAof9+tuYA2ofm8cAWXFmSfzDN8vQ=
-github.com/jakecoffman/cp v1.0.0/go.mod h1:JjY/Fp6d8E1CHnu74gWNnU0+b9VzEdUVPoJxg2PsTQg=
 github.com/jakecoffman/cp v1.1.0/go.mod h1:JjY/Fp6d8E1CHnu74gWNnU0+b9VzEdUVPoJxg2PsTQg=
 github.com/jezek/xgb v0.0.0-20210312150743-0e0f116e1240 h1:dy+DS31tGEGCsZzB45HmJJNHjur8GDgtRNX9U7HnSX4=
 github.com/jezek/xgb v0.0.0-20210312150743-0e0f116e1240/go.mod h1:3P4UH/k22rXyHIJD2w4h2XMqPX4Of/eySEZq9L6wqc4=
-github.com/jfreymuth/oggvorbis v1.0.1/go.mod h1:NqS+K+UXKje0FUYUPosyQ+XTVvjmVjps1aEZH1sumIk=
 github.com/jfreymuth/oggvorbis v1.0.3/go.mod h1:1U4pqWmghcoVsCJJ4fRBKv9peUJMBHixthRlBeD6uII=
-github.com/jfreymuth/vorbis v1.0.0/go.mod h1:8zy3lUAm9K/rJJk223RKy6vjCZTWC61NA2QD06bfOE0=
 github.com/jfreymuth/vorbis v1.0.2/go.mod h1:DoftRo4AznKnShRl1GxiTFCseHr4zR9BN3TWXyuzrqQ=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
 github.com/pkg/browser v0.0.0-20180916011732-0a3d74bf9ce4/go.mod h1:4OwLy04Bl9Ef3GJJCoec+30X3LQs/0/m4HFRt/2LUSA=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
@@ -36,48 +26,37 @@ github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZN
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
 github.com/yuin/goldmark v1.4.0/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
-golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190731235908-ec7cb31e5a56 h1:estk1glOnSVeJ9tdEZZc5mAMDZk5lNJNyJ6DvrBkTEU=
 golang.org/x/exp v0.0.0-20190731235908-ec7cb31e5a56/go.mod h1:JhuoJpWY28nO4Vef9tZUw9qufEGTyX1+7lmHxV5q5G4=
 golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
 golang.org/x/image v0.0.0-20190703141733-d6a02ce849c9/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/image v0.0.0-20190802002840-cff245a6509b/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
-golang.org/x/image v0.0.0-20200801110659-972c09e46d76/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d h1:RNPAfi2nHY7C2srAV8A49jpsYr0ADedCk1wq6fTMTvs=
 golang.org/x/image v0.0.0-20210628002857-a66eb6448b8d/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
 golang.org/x/mobile v0.0.0-20190312151609-d3739f865fa6/go.mod h1:z+o9i4GpDbdi3rU15maQ/Ox0txvL9dWGYEHz965HBQE=
 golang.org/x/mobile v0.0.0-20190415191353-3e0bab5405d6/go.mod h1:E/iHnbuqvinMTCcRqshq8CkpyQDoeVncDDYHnLhea+o=
-golang.org/x/mobile v0.0.0-20210208171126-f462b3930c8f/go.mod h1:skQtrUTUwhdJvXM/2KKJzY8pDgNr9I/FOMqDVRPBUS4=
 golang.org/x/mobile v0.0.0-20210902104108-5d9a33257ab5 h1:peBP2oZO/xVnGMaWMCyFEI0WENsGj71wx5K12mRELHQ=
 golang.org/x/mobile v0.0.0-20210902104108-5d9a33257ab5/go.mod h1:c4YKU3ZylDmvbw+H/PSvm42vhdWbuxCzbonauEAP9B8=
 golang.org/x/mod v0.1.0/go.mod h1:0QHyrYULN0/3qlju5TqG8bIK38QM8yzMo5ekMj3DlcY=
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 golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
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 golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
 golang.org/x/net v0.0.0-20210805182204-aaa1db679c0d/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c h1:5KslGYwFpkhGh+Q16bwMP3cOontH8FOep7tGV86Y7SQ=
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190312061237-fead79001313/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190429190828-d89cdac9e872/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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@@ -92,14 +71,13 @@ golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190312151545-0bb0c0a6e846/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
-golang.org/x/tools v0.0.0-20200117012304-6edc0a871e69/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
-golang.org/x/tools v0.0.0-20200918232735-d647fc253266/go.mod h1:z6u4i615ZeAfBE4XtMziQW1fSVJXACjjbWkB/mvPzlU=
 golang.org/x/tools v0.1.2/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
 golang.org/x/tools v0.1.6/go.mod h1:LGqMHiF4EqQNHR1JncWGqT5BVaXmza+X+BDGol+dOxo=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
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+gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b h1:QRR6H1YWRnHb4Y/HeNFCTJLFVxaq6wH4YuVdsUOr75U=
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libretro/libretro.go

@@ -16,7 +16,7 @@ var emulator *chip8.Emulator
 
 //export Initialize
 func Initialize() {
-	emulator = chip8.NewEmulator()
+	emulator = chip8.NewEmulator(nil)
 }
 
 //export Deinitialize

main.go

@@ -0,0 +1,107 @@
+package main
+
+import (
+	_ "embed"
+	"log"
+	"time"
+
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/tangzero/chip8-emulator/chip8"
+)
+
+//go:embed test_opcode.ch8
+var DefaultROM []byte
+
+const (
+	ScreenScale = 20
+	Width       = chip8.Width * ScreenScale
+	Height      = chip8.Height * ScreenScale
+)
+
+type State = int
+
+const (
+	LoadingState State = iota
+	RunningState
+)
+
+// Keyboard Layout
+// 1 2 3 C
+// 4 5 6 D
+// 7 8 9 E
+// A 0 B F
+var KeyMapping = []ebiten.Key{
+	ebiten.KeyX,
+	ebiten.Key1,
+	ebiten.Key2,
+	ebiten.Key3,
+	ebiten.KeyQ,
+	ebiten.KeyW,
+	ebiten.KeyE,
+	ebiten.KeyA,
+	ebiten.KeyS,
+	ebiten.KeyD,
+	ebiten.KeyZ,
+	ebiten.KeyC,
+	ebiten.Key4,
+	ebiten.KeyR,
+	ebiten.KeyF,
+	ebiten.KeyV,
+}
+
+type UI struct {
+	Emulator *chip8.Emulator
+	State    State
+}
+
+func (ui *UI) Run() {
+	for {
+		ui.Emulator.Cycle()
+		time.Sleep(time.Millisecond * 2)
+	}
+}
+
+func (ui *UI) Update() error {
+	switch ui.State {
+	case LoadingState:
+		go ui.Run()
+		ui.State = RunningState
+	case RunningState:
+		ui.Emulator.UpdateTimers()
+	}
+	return nil
+}
+
+func (ui *UI) Draw(screen *ebiten.Image) {
+	frame := ebiten.NewImageFromImage(ui.Emulator.Display)
+
+	operation := new(ebiten.DrawImageOptions)
+	operation.GeoM.Scale(ScreenScale, ScreenScale)
+
+	screen.DrawImage(frame, operation)
+}
+
+func (ui *UI) Layout(outsideWidth, outsideHeight int) (int, int) {
+	return Width, Height
+}
+
+func KeyPressed(key uint8) bool {
+	return ebiten.IsKeyPressed(KeyMapping[key])
+}
+
+func main() {
+	rom := LoadROM()
+
+	ui := UI{
+		Emulator: chip8.NewEmulator(KeyPressed),
+		State:    LoadingState,
+	}
+	ui.Emulator.LoadROM(rom)
+
+	ebiten.SetWindowSize(Width, Height)
+	ebiten.SetWindowTitle("CHIP-8 : " + rom.Name)
+
+	if err := ebiten.RunGame(&ui); err != nil {
+		log.Fatal(err)
+	}
+}

main_desktop.go

@@ -0,0 +1,29 @@
+//go:build !js
+
+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"path"
+	"strings"
+
+	"github.com/tangzero/chip8-emulator/chip8"
+)
+
+func LoadROM() chip8.ROM {
+	data := DefaultROM
+	name := "test_opcode"
+
+	if len(os.Args) > 1 {
+		bytes, err := ioutil.ReadFile(os.Args[1])
+		if err != nil {
+			log.Fatal(err)
+		}
+		data = bytes
+		name = strings.Split(path.Base(os.Args[1]), ".")[0]
+	}
+
+	return chip8.ROM{Data: data, Name: name}
+}

main_web.go

@@ -0,0 +1,11 @@
+//go:build js
+
+package main
+
+import "github.com/tangzero/chip8-emulator/chip8"
+
+func LoadROM() chip8.ROM {
+	data := DefaultROM
+	name := "test_opcode"
+	return chip8.ROM{Data: data, Name: name}
+}

roms/README.md

@@ -0,0 +1,38 @@
+# CHIP-8 Public Domain ROMs
+
+* Chip-8 Games Pack:
+  * Puzzle
+  * Blinky
+  * Blitz
+  * Brix
+  * Connect 4
+  * Guess
+  * Hidden
+  * Invaders
+  * Kaleid
+  * Maze
+  * Merun
+  * Missle
+  * Pong
+  * Pong 2
+  * Puzzle
+  * Syzgy
+  * Tank
+  * Tetris
+  * TicTac
+  * UFO
+  * Vbrix
+  * Wipeoff
+
+* Super Chip Games Pack:
+  * Alien
+  * Ant
+  * Blinky
+  * Car
+  * Field
+  * Joust
+  * Piper
+  * Race
+  * Spacefig
+  * Uboat
+  * Worm3