Separate chip8 & sdl pkgs, update readme, add roms

README.md

@@ -1,7 +1,15 @@
-# go-chip8
+# go-chip8 [![Go Report Card](https://goreportcard.com/badge/github.com/arnaucube/go-chip8)](https://goreportcard.com/report/github.com/arnaucube/go-chip8)
 
 CHIP-8 emulator written in Go.
 
-[WIP]
-
 https://en.wikipedia.org/wiki/CHIP-8
+
+### Usage
+```
+go run main.go -file roms/invaders.c8
+```
+
+![](screenshots/s00.png)
+![](screenshots/s01.png)
+![](screenshots/s02.png)
+![](screenshots/s03.png)

chip8/chip8.go

@@ -0,0 +1,395 @@
+package chip8
+
+import (
+	"fmt"
+	"io/ioutil"
+	"math/rand"
+)
+
+// W represents the width of the screen
+const W = 64
+
+// H represents the height of the screen
+const H = 32
+
+// Chip8 contains all the data and methods for the Chip8 emulator
+type Chip8 struct {
+	opcode uint16
+	memory [4096]byte
+
+	// register
+	v [16]byte
+
+	index uint16
+	pc    uint16
+
+	Gfx [W * H]byte
+
+	delayTimer byte
+	soundTimer byte
+
+	stack [16]uint16
+	sp    int
+
+	Key [16]byte
+
+	DrawFlag bool
+}
+
+// Initialize registers and memory
+func (c *Chip8) Initialize() {
+	c.pc = 0x200
+	c.opcode = 0
+	c.index = 0
+	c.sp = 0
+
+	for i := 0; i < len(fontSet); i++ {
+		c.memory[i] = fontSet[i]
+	}
+}
+
+// EmulateCycle emulates the chip8 cycle
+func (c *Chip8) EmulateCycle() {
+	// Fetch Opcode
+	c.opcode = uint16(c.memory[c.pc])<<8 | uint16(c.memory[c.pc+1])
+	x := byte((c.opcode & 0x0F00) >> 8)
+	y := byte((c.opcode & 0x00F0) >> 4)
+	nn := byte(c.opcode & 0x00FF)
+	nnn := uint16(c.opcode & 0x0FFF)
+
+	// Decode Opcode
+	// https://en.wikipedia.org/wiki/CHIP-8#Opcode_table
+	// http://www.multigesture.net/wp-content/uploads/mirror/goldroad/chip8_instruction_set.shtml
+	switch c.opcode & 0xF000 {
+	case 0x0000:
+		switch c.opcode & 0x000F {
+		case 0x0000:
+			// 00E0 Clear screen
+			for i := 0; i < len(c.Gfx); i++ {
+				c.Gfx[i] = 0
+			}
+			c.pc += 2
+			c.DrawFlag = true
+			break
+		case 0x000E:
+			// 00EE Returns from a subroutine
+			c.sp--
+			c.pc = c.stack[c.sp]
+			c.pc += 2
+			break
+		default:
+			fmt.Printf("Unknown opcode [0x0000]: 0x%X\n", c.opcode)
+		}
+	case 0x1000:
+		// 1NNN Jumps to address NNN
+		c.pc = nnn
+		break
+	case 0x2000:
+		// 2NNN Calls subroutine at NNN
+		c.stack[c.sp] = c.pc
+		c.sp++
+		c.pc = nnn
+		break
+	case 0x3000:
+		// 3XNN Skips the next instruction if VX equals NN. (Usually
+		// the next instruction is a jump to skip a code block)
+		if c.v[x] == nn {
+			c.pc += 2
+		}
+		c.pc += 2
+		break
+	case 0x4000:
+		// 4XNN Skips the next instruction if VX doesn't equal NN.
+		// (Usually the next instruction is a jump to skip a code
+		// block)
+		if c.v[x] != nn {
+			c.pc += 2
+		}
+		c.pc += 2
+		break
+	case 0x5000:
+		// 5XY0 Skips the next instruction if VX equals VY. (Usually
+		// the next instruction is a jump to skip a code block)
+		if c.v[x] != c.v[y] {
+			c.pc += 2
+		}
+		c.pc += 2
+		break
+	case 0x6000:
+		// 6XNN Sets VX to NN
+		c.v[x] = nn
+		c.pc += 2
+		break
+	case 0x7000:
+		// 7XNN Adds NN to VX. (Carry flag is not changed)
+		c.v[x] += nn
+		c.pc += 2
+		break
+	case 0x8000:
+		switch c.opcode & 0x000F {
+		case 0x0000:
+			// 0x8XY0 Sets VX to the value of VY
+			c.v[x] = c.v[y]
+			c.pc += 2
+		case 0x0001:
+			// 0x8XY1 Sets VX to VX or VY. (Bitwise OR operation)
+			c.v[x] = (c.v[x] | c.v[y])
+			c.pc += 2
+		case 0x0002:
+			// 0x8XY2 Sets VX to VX and VY. (Bitwise AND operation)
+			c.v[x] = (c.v[x] & c.v[y])
+			c.pc += 2
+		case 0x0003:
+			// 0x8XY3 Sets VX to VX xor VY
+			c.v[x] = (c.v[x] ^ c.v[y])
+			c.pc += 2
+		case 0x0004:
+			// 0x8XY4 Adds VY to VX. VF is set to 1 when there's a
+			// carry, and to 0 when there isn't
+			if c.v[y] > (0xFF - c.v[x]) {
+				c.v[0xF] = 1
+			} else {
+				c.v[0xF] = 0
+			}
+			c.v[x] += c.v[y]
+			c.pc += 2
+			break
+		case 0x0005:
+			// 0x8XY5 VY is subtracted from VX. VF is set to 0 when
+			// there's a borrow, and 1 when there isn't
+			if c.v[x] > c.v[y] {
+				c.v[0xF] = 0x1
+			} else {
+				c.v[0xF] = 0x0
+			}
+			c.v[x] -= c.v[y]
+			c.pc += 2
+		case 0x0006:
+			// 0x8XY6 Stores the least significant bit of VX in VF
+			// and then shifts VX to the right by 1
+			if c.opcode&0x1 >= 1 {
+				c.v[0xF] = 1
+			} else {
+				c.v[0xF] = 0
+			}
+			c.v[x] = c.v[x] >> 1
+			c.pc += 2
+		case 0x0007:
+			// 0x8XY7 Sets VX to VY minus VX. VF is set to 0 when
+			// there's a borrow, and 1 when there isn't
+			if c.v[y] > c.v[x] {
+				c.v[0xF] = 0x1
+			} else {
+				c.v[0xF] = 0x0
+			}
+			c.v[x] = c.v[y] - c.v[x]
+			c.pc += 2
+		case 0x000E:
+			// 0x8XYE Stores the most significant bit of VX in VF
+			// and then shifts VX to the left by 1
+			if c.opcode&0x80 == 0x80 {
+				c.v[0xF] = 1
+			} else {
+				c.v[0xF] = 0
+			}
+			c.v[x] = c.v[x] << 1
+			c.pc += 2
+		default:
+			fmt.Printf("Unknown opcode [0x8000]: 0x%X\n", c.opcode)
+		}
+	case 0x9000:
+		// 9XY0 Skips the next instruction if VX doesn't equal VY.
+		// (Usually the next instruction is a jump to skip a code
+		// block)
+		if c.v[x] != c.v[y] {
+			c.pc += 2
+		}
+		c.pc += 2
+	case 0xA000:
+		// ANNN set index to NNN position
+		c.index = nnn
+		c.pc += 2
+		break
+	case 0xB000:
+		// BNNN Jumps to the address NNN plus V0
+		c.pc = nnn + uint16(c.v[0])
+	case 0xC000:
+		// CXNN Sets VX to the result of a bitwise and operation on a
+		// random number (Typically: 0 to 255) and NN
+		r := byte(rand.Intn(255))
+		c.v[x] = r & nn
+		c.pc += 2
+	case 0xD000:
+		// DXYN Draws a sprite at coordinate (VX, VY) that has a width
+		// of 8 pixels and a height of N+1 pixels. Each row of 8 pixels
+		// is read as bit-coded starting from memory location I; I
+		// value doesn’t change after the execution of this
+		// instruction. As described above, VF is set to 1 if any
+		// screen pixels are flipped from set to unset when the sprite
+		// is drawn, and to 0 if that doesn’t happen
+
+		height := c.opcode & 0x000F
+
+		var pixel byte
+		c.v[0xF] = 0
+
+		for yline := uint16(0); yline < height; yline++ {
+			pixel = c.memory[c.index+yline]
+			for xline := uint16(0); xline < 8; xline++ {
+				if (pixel & (0x80 >> xline)) != 0 {
+					pos := (uint16(c.v[x]) + xline) + ((uint16(c.v[y]) + yline) * W)
+					if pos >= 2048 {
+						break
+					}
+					if c.Gfx[pos] == 1 {
+						c.v[0xF] = 1
+					}
+					c.Gfx[pos] ^= 1
+				}
+			}
+
+		}
+
+		c.DrawFlag = true
+		c.pc += 2
+		break
+	case 0xE000:
+		switch c.opcode & 0x00FF {
+		case 0x009E:
+			// EX9E Skips the next instruction if the key stored in
+			// VX is pressed. (Usually the next instruction is a
+			// jump to skip a code block)
+			if c.Key[c.v[x]] != 0 {
+				c.pc += 2
+			}
+			c.pc += 2
+			break
+		case 0x00A1:
+			// EXA1 Skips the next instruction if the key stored in
+			// VX isn't pressed. (Usually the next instruction is a
+			// jump to skip a code block)
+			if c.Key[c.v[x]] != 1 {
+				c.pc += 2
+			}
+			c.pc += 2
+		default:
+			fmt.Printf("Unknown opcode [0xE000]: 0x%X\n", c.opcode)
+		}
+		break
+	case 0xF000:
+		switch c.opcode & 0x00FF {
+		case 0x0007:
+			// FX07 Sets VX to the value of the delay timer
+			c.v[x] = c.delayTimer
+			c.pc += 2
+		case 0x000A:
+			// FX0A A key press is awaited, and then stored in VX.
+			// (Blocking Operation. All instruction halted until
+			// next key event)
+			pressed := false
+			for i := 0; i < 16; i++ {
+				if c.Key[i] == 1 {
+					c.v[x] = byte(i)
+					pressed = true
+				}
+			}
+			if !pressed {
+				return
+			}
+			c.pc += 2
+		case 0x0015:
+			// FX15 Sets the delay timer to VX
+			c.delayTimer = c.v[x]
+			c.pc += 2
+		case 0x0018:
+			// FX18 Sets the sound timer to VX
+			c.soundTimer = c.v[x]
+			c.pc += 2
+		case 0x001E:
+			// FX1E Adds VX to I. VF is not affected
+			c.index += uint16(c.v[x])
+			c.pc += 2
+		case 0x0029:
+			// FX29 Sets I to the location of the sprite for the
+			// character in VX. Characters 0-F (in hexadecimal) are
+			// represented by a 4x5 font
+			c.index = uint16(c.v[x]) * 5
+			c.pc += 2
+			break
+		case 0x0033:
+			c.memory[c.index] = c.v[x] / 100
+			c.memory[c.index+1] = (c.v[x] / 10) % 10
+			c.memory[c.index+2] = (c.v[x] / 100) % 10
+			c.pc += 2
+			break
+		case 0x0055:
+			// FX55 Stores V0 to VX (including VX) in memory
+			// starting at address I. The offset from I is
+			// increased by 1 for each value written, but I itself
+			// is left unmodified
+			for i := uint16(0); i <= uint16(x); i++ {
+				c.memory[c.index+i] = c.v[i]
+			}
+			c.pc += 2
+		case 0x0065:
+			// 0xFX65 Fills V0 to VX (including VX) with values
+			// from memory starting at address I. The offset from I
+			// is increased by 1 for each value written, but I
+			// itself is left unmodified
+			for i := uint16(0); i < uint16(x)+1; i++ {
+				c.v[i] = c.memory[c.index+i]
+			}
+			c.pc += 2
+			break
+		default:
+			fmt.Printf("Unknown opcode [0xF000]: 0x%X\n", c.opcode)
+		}
+		break
+	default:
+		fmt.Printf("Unknown opcode: 0x%X\n", c.opcode)
+	}
+
+	// Update timers
+	if c.delayTimer > 0 {
+		c.delayTimer--
+	}
+	if c.soundTimer > 0 {
+		if c.soundTimer == 1 {
+			fmt.Printf("Beep!\n")
+		}
+		c.soundTimer--
+	}
+}
+
+// LoadGame loads the rom file of the given file path into the Chip8 memory
+func (c *Chip8) LoadGame(filepath string) error {
+	buffer, err := ioutil.ReadFile(filepath)
+	if err != nil {
+		return err
+	}
+
+	for i := 0; i < len(buffer); i++ {
+		// 0x200 == 512
+		c.memory[512+i] = buffer[i]
+	}
+	return nil
+}
+
+var fontSet = [80]byte{
+	0xF0, 0x90, 0x90, 0x90, 0xF0, // 0
+	0x20, 0x60, 0x20, 0x20, 0x70, // 1
+	0xF0, 0x10, 0xF0, 0x80, 0xF0, // 2
+	0xF0, 0x10, 0xF0, 0x10, 0xF0, // 3
+	0x90, 0x90, 0xF0, 0x10, 0x10, // 4
+	0xF0, 0x80, 0xF0, 0x10, 0xF0, // 5
+	0xF0, 0x80, 0xF0, 0x90, 0xF0, // 6
+	0xF0, 0x10, 0x20, 0x40, 0x40, // 7
+	0xF0, 0x90, 0xF0, 0x90, 0xF0, // 8
+	0xF0, 0x90, 0xF0, 0x10, 0xF0, // 9
+	0xF0, 0x90, 0xF0, 0x90, 0x90, // A
+	0xE0, 0x90, 0xE0, 0x90, 0xE0, // B
+	0xF0, 0x80, 0x80, 0x80, 0xF0, // C
+	0xE0, 0x90, 0x90, 0x90, 0xE0, // D
+	0xF0, 0x80, 0xF0, 0x80, 0xF0, // E
+	0xF0, 0x80, 0xF0, 0x80, 0x80, // F
+}

go.mod

@@ -0,0 +1,5 @@
+module go-chip8
+
+go 1.14
+
+require github.com/veandco/go-sdl2 v0.4.4

go.sum

@@ -0,0 +1,2 @@
+github.com/veandco/go-sdl2 v0.4.4 h1:coOJGftOdvNvGoUIZmm4XD+ZRQF4mg9ZVHmH3/42zFQ=
+github.com/veandco/go-sdl2 v0.4.4/go.mod h1:FB+kTpX9YTE+urhYiClnRzpOXbiWgaU3+5F2AB78DPg=

main.go

@@ -3,489 +3,86 @@ package main
 import (
 	"flag"
 	"fmt"
-	"io/ioutil"
-	"math/rand"
+	"go-chip8/chip8"
 	"os"
 
 	"github.com/veandco/go-sdl2/sdl"
 )
 
-const w = 64
-const h = 32
-
-type chip8 struct {
-	opcode uint16
-	memory [4096]byte
-
-	// register
-	v [16]byte
-
-	index uint16
-	pc    uint16
-
-	gfx [w * h]byte
-
-	delayTimer byte
-	soundTimer byte
-
-	stack [16]uint16
-	sp    int
-
-	key [16]byte
-
-	drawFlag bool
-
-	// graphics
+// SdlEmulator represents the Chip8 emulator with Sdl frontend
+type SdlEmulator struct {
+	w        int
+	h        int
 	renderer *sdl.Renderer
 	zoom     int32
+	chip8    chip8.Chip8
 }
 
-// Initialize registers and memory once
-func (c *chip8) initialize() {
-	c.pc = 0x200
-	c.opcode = 0
-	c.index = 0
-	c.sp = 0
-	c.zoom = 8
-
-	for i := 0; i < len(fontSet); i++ {
-		c.memory[i] = fontSet[i]
-	}
-}
-
-func (c *chip8) emulateCycle() {
-	// Fetch Opcode
-	c.opcode = uint16(c.memory[c.pc])<<8 | uint16(c.memory[c.pc+1])
-	x := byte((c.opcode & 0x0F00) >> 8)
-	y := byte((c.opcode & 0x00F0) >> 4)
-	nn := byte(c.opcode & 0x00FF)
-	nnn := uint16(c.opcode & 0x0FFF)
-	// fmt.Printf("%X\n", c.opcode)
-
-	// Decode Opcode
-	// https://en.wikipedia.org/wiki/CHIP-8#Opcode_table
-	// http://www.multigesture.net/wp-content/uploads/mirror/goldroad/chip8_instruction_set.shtml
-	switch c.opcode & 0xF000 {
-	case 0x0000:
-		switch c.opcode & 0x000F {
-		case 0x0000:
-			// 00E0 Clear screen
-			for i := 0; i < len(c.gfx); i++ {
-				c.gfx[i] = 0
-			}
-			c.pc += 2
-			c.drawFlag = true
-			break
-		case 0x000E:
-			// 00EE Returns from a subroutine
-			c.sp--
-			c.pc = c.stack[c.sp]
-			c.pc += 2
-			break
-		default:
-			fmt.Printf("Unknown opcode [0x0000]: 0x%X\n", c.opcode)
-		}
-	case 0x1000:
-		// 1NNN Jumps to address NNN
-		// c.pc = c.opcode & 0x0FFF
-		c.pc = nnn
-		break
-	case 0x2000:
-		// 2NNN Calls subroutine at NNN
-		c.stack[c.sp] = c.pc
-		c.sp++
-		// c.pc = c.opcode & 0x0FFF
-		c.pc = nnn
-		break
-	case 0x3000:
-		// 3XNN Skips the next instruction if VX equals NN. (Usually
-		// the next instruction is a jump to skip a code block)
-		if c.v[x] == nn {
-			c.pc += 2
-		}
-		c.pc += 2
-		break
-	case 0x4000:
-		// 4XNN Skips the next instruction if VX doesn't equal NN.
-		// (Usually the next instruction is a jump to skip a code
-		// block)
-		if c.v[x] != nn {
-			c.pc += 2
-		}
-		c.pc += 2
-		break
-	case 0x5000:
-		// 5XY0 Skips the next instruction if VX equals VY. (Usually
-		// the next instruction is a jump to skip a code block)
-		if c.v[x] != c.v[y] {
-			c.pc += 2
-		}
-		c.pc += 2
-		break
-	case 0x6000:
-		// 6XNN Sets VX to NN
-		c.v[x] = nn
-		c.pc += 2
-		break
-	case 0x7000:
-		// 7XNN Adds NN to VX. (Carry flag is not changed)
-		// c.v[c.opcode&0x0F00>>8] += byte(c.opcode)
-		c.v[x] += nn
-		c.pc += 2
-		break
-	case 0x8000:
-		switch c.opcode & 0x000F {
-		case 0x0000:
-			// 0x8XY0 Sets VX to the value of VY
-			c.v[x] = c.v[y]
-			c.pc += 2
-		case 0x0001:
-			// 0x8XY1 Sets VX to VX or VY. (Bitwise OR operation)
-			c.v[x] = (c.v[x] | c.v[y])
-			c.pc += 2
-		case 0x0002:
-			// 0x8XY2 Sets VX to VX and VY. (Bitwise AND operation)
-			c.v[x] = (c.v[x] & c.v[y])
-			c.pc += 2
-		case 0x0003:
-			// 0x8XY3 Sets VX to VX xor VY
-			c.v[x] = (c.v[x] ^ c.v[y])
-			c.pc += 2
-		case 0x0004:
-			// 0x8XY4 Adds VY to VX. VF is set to 1 when there's a
-			// carry, and to 0 when there isn't
-			if c.v[y] > (0xFF - c.v[x]) {
-				c.v[0xF] = 1
-			} else {
-				c.v[0xF] = 0
-			}
-			c.v[x] += c.v[y]
-			c.pc += 2
-			break
-		case 0x0005:
-			// 0x8XY5 VY is subtracted from VX. VF is set to 0 when
-			// there's a borrow, and 1 when there isn't
-			if c.v[x] > c.v[y] {
-				c.v[0xF] = 0x1
-			} else {
-				c.v[0xF] = 0x0
-			}
-			c.v[x] -= c.v[y]
-			c.pc += 2
-		case 0x0006:
-			// 0x8XY6 Stores the least significant bit of VX in VF
-			// and then shifts VX to the right by 1
-			if c.opcode&0x1 >= 1 {
-				c.v[0xF] = 1
-			} else {
-				c.v[0xF] = 0
-			}
-			c.v[x] = c.v[x] >> 1
-			c.pc += 2
-		case 0x0007:
-			// 0x8XY7 Sets VX to VY minus VX. VF is set to 0 when
-			// there's a borrow, and 1 when there isn't
-			if c.v[y] > c.v[x] {
-				c.v[0xF] = 0x1
-			} else {
-				c.v[0xF] = 0x0
-			}
-			c.v[x] = c.v[y] - c.v[x]
-			c.pc += 2
-		case 0x000E:
-			// 0x8XYE Stores the most significant bit of VX in VF
-			// and then shifts VX to the left by 1
-			if c.opcode&0x80 == 0x80 {
-				c.v[0xF] = 1
-			} else {
-				c.v[0xF] = 0
-			}
-			c.v[x] = c.v[x] << 1
-			c.pc += 2
-		default:
-			fmt.Printf("Unknown opcode [0x8000]: 0x%X\n", c.opcode)
-		}
-	case 0x9000:
-		// 9XY0 Skips the next instruction if VX doesn't equal VY.
-		// (Usually the next instruction is a jump to skip a code
-		// block)
-		if c.v[x] != c.v[y] {
-			c.pc += 2
-		}
-		c.pc += 2
-	case 0xA000:
-		// ANNN set index to NNN position
-		c.index = nnn
-		c.pc += 2
-		break
-	case 0xB000:
-		// BNNN Jumps to the address NNN plus V0
-		c.pc = nnn + uint16(c.v[0])
-	case 0xC000:
-		// CXNN Sets VX to the result of a bitwise and operation on a
-		// random number (Typically: 0 to 255) and NN
-		r := byte(rand.Intn(255))
-		c.v[x] = r & nn
-		c.pc += 2
-	case 0xD000:
-		// DXYN Draws a sprite at coordinate (VX, VY) that has a width
-		// of 8 pixels and a height of N+1 pixels. Each row of 8 pixels
-		// is read as bit-coded starting from memory location I; I
-		// value doesn’t change after the execution of this
-		// instruction. As described above, VF is set to 1 if any
-		// screen pixels are flipped from set to unset when the sprite
-		// is drawn, and to 0 if that doesn’t happen
-
-		height := c.opcode & 0x000F
-
-		var pixel byte
-		c.v[0xF] = 0
+// NewSdlEmulator creates a new SdlEmulator
+func NewSdlEmulator(w, h int, zoom int32) SdlEmulator {
+	var c chip8.Chip8
+	c.Initialize()
 
-		for yline := uint16(0); yline < height; yline++ {
-			pixel = c.memory[c.index+yline]
-			for xline := uint16(0); xline < 8; xline++ {
-				if (pixel & (0x80 >> xline)) != 0 {
-					pos := (uint16(c.v[x]) + xline) + ((uint16(c.v[y]) + yline) * w)
-					if pos >= 2048 {
-						break
-					}
-					if c.gfx[pos] == 1 {
-						c.v[0xF] = 1
-					}
-					c.gfx[pos] ^= 1
-				}
-			}
-
-		}
-
-		c.drawFlag = true
-		c.pc += 2
-		break
-	case 0xE000:
-		switch c.opcode & 0x00FF {
-		case 0x009E:
-			// EX9E Skips the next instruction if the key stored in
-			// VX is pressed. (Usually the next instruction is a
-			// jump to skip a code block)
-			if c.key[c.v[x]] != 0 {
-				c.pc += 2
-			}
-			c.pc += 2
-			break
-		case 0x00A1:
-			// EXA1 Skips the next instruction if the key stored in
-			// VX isn't pressed. (Usually the next instruction is a
-			// jump to skip a code block)
-			if c.key[c.v[x]] != 1 {
-				c.pc += 2
-			}
-			c.pc += 2
-		default:
-			fmt.Printf("Unknown opcode [0xE000]: 0x%X\n", c.opcode)
-		}
-		break
-	case 0xF000:
-		switch c.opcode & 0x00FF {
-		case 0x0007:
-			// FX07 Sets VX to the value of the delay timer
-			c.v[x] = c.delayTimer
-			c.pc += 2
-		case 0x000A:
-			// FX0A A key press is awaited, and then stored in VX.
-			// (Blocking Operation. All instruction halted until
-			// next key event)
-			pressed := false
-			for i := 0; i < 16; i++ {
-				if c.key[i] == 1 {
-					c.v[x] = byte(i)
-					pressed = true
-				}
-			}
-			if !pressed {
-				return
-			}
-			c.pc += 2
-		case 0x0015:
-			// FX15 Sets the delay timer to VX
-			c.delayTimer = c.v[x]
-			c.pc += 2
-		case 0x0018:
-			// FX18 Sets the sound timer to VX
-			c.soundTimer = c.v[x]
-			c.pc += 2
-		case 0x001E:
-			// FX1E Adds VX to I. VF is not affected
-			c.index += uint16(c.v[x])
-			c.pc += 2
-		case 0x0029:
-			// FX29 Sets I to the location of the sprite for the
-			// character in VX. Characters 0-F (in hexadecimal) are
-			// represented by a 4x5 font
-			c.index = uint16(c.v[x]) * 5
-			c.pc += 2
-			break
-		case 0x0033:
-			c.memory[c.index] = c.v[x] / 100
-			c.memory[c.index+1] = (c.v[x] / 10) % 10
-			c.memory[c.index+2] = (c.v[x] / 100) % 10
-			c.pc += 2
-			break
-		case 0x0055:
-			// FX55 Stores V0 to VX (including VX) in memory
-			// starting at address I. The offset from I is
-			// increased by 1 for each value written, but I itself
-			// is left unmodified
-			for i := uint16(0); i <= uint16(x); i++ {
-				c.memory[c.index+i] = c.v[i]
-			}
-			c.pc += 2
-		case 0x0065:
-			// 0xFX65 Fills V0 to VX (including VX) with values
-			// from memory starting at address I. The offset from I
-			// is increased by 1 for each value written, but I
-			// itself is left unmodified
-			for i := uint16(0); i < uint16(x)+1; i++ {
-				c.v[i] = c.memory[c.index+i]
-			}
-			c.pc += 2
-			break
-		default:
-			fmt.Printf("Unknown opcode [0xF000]: 0x%X\n", c.opcode)
-		}
-		break
-	default:
-		fmt.Printf("Unknown opcode: 0x%X\n", c.opcode)
-	}
-
-	// Update timers
-	if c.delayTimer > 0 {
-		c.delayTimer--
-	}
-	if c.soundTimer > 0 {
-		if c.soundTimer == 1 {
-			fmt.Printf("Beep!\n")
-		}
-		c.soundTimer--
-	}
-}
-
-func (c *chip8) loadGame(filepath string) error {
-	buffer, err := ioutil.ReadFile(filepath)
-	if err != nil {
-		return err
-	}
-
-	for i := 0; i < len(buffer); i++ {
-		// 0x200 == 512
-		c.memory[512+i] = buffer[i]
-	}
-	return nil
-}
-
-var fontSet = [80]byte{
-	0xF0, 0x90, 0x90, 0x90, 0xF0, // 0
-	0x20, 0x60, 0x20, 0x20, 0x70, // 1
-	0xF0, 0x10, 0xF0, 0x80, 0xF0, // 2
-	0xF0, 0x10, 0xF0, 0x10, 0xF0, // 3
-	0x90, 0x90, 0xF0, 0x10, 0x10, // 4
-	0xF0, 0x80, 0xF0, 0x10, 0xF0, // 5
-	0xF0, 0x80, 0xF0, 0x90, 0xF0, // 6
-	0xF0, 0x10, 0x20, 0x40, 0x40, // 7
-	0xF0, 0x90, 0xF0, 0x90, 0xF0, // 8
-	0xF0, 0x90, 0xF0, 0x10, 0xF0, // 9
-	0xF0, 0x90, 0xF0, 0x90, 0x90, // A
-	0xE0, 0x90, 0xE0, 0x90, 0xE0, // B
-	0xF0, 0x80, 0x80, 0x80, 0xF0, // C
-	0xE0, 0x90, 0x90, 0x90, 0xE0, // D
-	0xF0, 0x80, 0xF0, 0x80, 0xF0, // E
-	0xF0, 0x80, 0xF0, 0x80, 0x80, // F
-}
-
-func (c *chip8) setupInput() {
-}
-
-func (c *chip8) setupGraphics() {
-	fmt.Println(c.zoom)
 	window, err := sdl.CreateWindow("go-chip8", sdl.WINDOWPOS_UNDEFINED,
-		sdl.WINDOWPOS_UNDEFINED, w*c.zoom, h*c.zoom, sdl.WINDOW_SHOWN)
+		sdl.WINDOWPOS_UNDEFINED, int32(w)*zoom, int32(h)*zoom, sdl.WINDOW_SHOWN)
 	if err != nil {
 		panic(err)
 	}
-	c.renderer, err = sdl.CreateRenderer(window, -1, 0)
+	renderer, err := sdl.CreateRenderer(window, -1, 0)
 	if err != nil {
 		panic(err)
 	}
-}
 
-func (c *chip8) drawGraphics() {
-	// x := 0
-	// y := 0
-	// for i := 0; i < len(c.gfx); i++ {
-	//         if i%w == 0 {
-	//                 x = 0
-	//                 y++
-	//                 fmt.Println("")
-	//         }
-	//         if c.gfx[i]^1 == 0 {
-	//                 c.renderer.DrawPoint(int32(x), int32(y))
-	//                 fmt.Print("x")
-	//         } else {
-	//                 fmt.Print(" ")
-	//         }
-	//         x++
-	// }
-
-	// for y := 0; y < h; y++ {
-	//         for x := 0; x < w; x++ {
-	//                 pixel := c.gfx[y*w+x]
-	//                 if pixel != 0 {
-	//                         c.renderer.DrawPoint(int32(x), int32(y))
-	//                 }
-	//         }
-	// }
+	return SdlEmulator{
+		w:        w,
+		h:        h,
+		renderer: renderer,
+		zoom:     zoom,
+		chip8:    c,
+	}
+}
 
-	c.renderer.SetDrawColor(0, 0, 0, 1)
-	c.renderer.Clear()
-	c.renderer.SetDrawColor(255, 255, 255, 1)
-	for y := 0; y < h; y++ {
-		for x := 0; x < w; x++ {
-			pixel := c.gfx[y*w+x]
+func (e *SdlEmulator) drawGraphics() {
+	e.renderer.SetDrawColor(0, 0, 0, 1)
+	e.renderer.Clear()
+	e.renderer.SetDrawColor(255, 255, 255, 1)
+	for y := 0; y < e.h; y++ {
+		for x := 0; x < e.w; x++ {
+			pixel := e.chip8.Gfx[y*e.w+x]
 			if pixel != 0 {
-				c.renderer.FillRect(&sdl.Rect{
-					X: int32(x) * c.zoom,
-					Y: int32(y) * c.zoom,
-					W: c.zoom,
-					H: c.zoom,
+				e.renderer.FillRect(&sdl.Rect{
+					X: int32(x) * e.zoom,
+					Y: int32(y) * e.zoom,
+					W: e.zoom,
+					H: e.zoom,
 				})
 			}
 		}
 	}
 
-	c.renderer.Present()
-	c.drawFlag = false
+	e.renderer.Present()
+	e.chip8.DrawFlag = false
 }
 
-func (c *chip8) setKeys() {
+func (e *SdlEmulator) setKeys() {
 	for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
 		switch t := event.(type) {
 		case *sdl.QuitEvent:
-			println("Quit")
+			fmt.Println("Quit")
 			os.Exit(0)
-			// running = false
-			// break
 		case *sdl.KeyboardEvent:
 			switch t.Type {
 			case sdl.KEYDOWN:
 				if keyHex, ok := validKeys[t.Keysym.Sym]; ok {
 					fmt.Println("down", t.Keysym.Sym)
-					c.key[keyHex] = 1
-					fmt.Println(keyHex, c.key[keyHex])
+					e.chip8.Key[keyHex] = 1
+					fmt.Println(keyHex, e.chip8.Key[keyHex])
 				}
 			case sdl.KEYUP:
 				if keyHex, ok := validKeys[t.Keysym.Sym]; ok {
 					fmt.Println("up", t.Keysym.Sym)
-					c.key[keyHex] = 0
-					fmt.Println(keyHex, c.key[keyHex])
+					e.chip8.Key[keyHex] = 0
+					fmt.Println(keyHex, e.chip8.Key[keyHex])
 				}
 				if t.Keysym.Sym == sdl.K_ESCAPE {
 					fmt.Println("EXIT")
@@ -528,22 +125,19 @@ func main() {
 
 	flag.Parse()
 
-	var c chip8
-	c.initialize()
-	c.setupGraphics()
-	c.setupInput()
+	emulator := NewSdlEmulator(chip8.W, chip8.H, 8)
 
-	err := c.loadGame(*filepath)
+	err := emulator.chip8.LoadGame(*filepath)
 	if err != nil {
 		panic(err)
 	}
 
 	for {
-		c.emulateCycle()
-		if c.drawFlag {
-			c.drawGraphics()
+		emulator.chip8.EmulateCycle()
+		if emulator.chip8.DrawFlag {
+			emulator.drawGraphics()
 		}
-		c.setKeys()
-		sdl.Delay(100 / 60)
+		emulator.setKeys()
+		sdl.Delay(200 / 60)
 	}
 }