Fixes type casting on key presses.

Implements remainder of opcodes.

cmd/chip8/main.go

@@ -20,7 +20,7 @@ var (
 	window *pixelgl.Window
 
 	// TODO: Abstract this.
-	keys = map[uint16]pixelgl.Button{
+	keys = map[byte]pixelgl.Button{
 		0x1: pixelgl.Key1, 0x2: pixelgl.Key2, 0x3: pixelgl.Key3, 0xC: pixelgl.Key4,
 		0x4: pixelgl.KeyQ, 0x5: pixelgl.KeyW, 0x6: pixelgl.KeyE, 0xD: pixelgl.KeyR,
 		0x7: pixelgl.KeyA, 0x8: pixelgl.KeyS, 0x9: pixelgl.KeyD, 0xE: pixelgl.KeyF,
@@ -73,8 +73,6 @@ func run() {
 		log.Fatal("Could not create window:", err)
 	}
 
-	// TODO: Setup input.
-
 	vm = chip8.New()
 	vm.Debug = debug
 

internal/chip8/opcodes.go

@@ -64,7 +64,10 @@ func (v *VM) registerHandlers() {
 			opcode:  "ANNN",
 			handler: v.setAddress,
 		},
-		// TODO: BNNN
+		0xB000: {
+			opcode:  "BNNN",
+			handler: v.jumpV0,
+		},
 		0xC000: {
 			opcode:  "CXNN",
 			handler: v.setVxRand,
@@ -359,8 +362,8 @@ func (v *VM) decVxVy(x, y uint16) opcodeHandlerFunc {
 // to the right by 1.
 func (v *VM) setVFLeastVx(x, y uint16) opcodeHandlerFunc {
 	return func() (uint16, error) {
-		v.v[0xF] = v.v[x] & 1
 		v.v[x] >>= 1
+		v.v[0xF] = v.v[x] & 1
 
 		v.pc += 2
 
@@ -389,8 +392,8 @@ func (v *VM) setVxVyMinusVx(x, y uint16) opcodeHandlerFunc {
 // to the left by 1.
 func (v *VM) setVFMostVx(x, y uint16) opcodeHandlerFunc {
 	return func() (uint16, error) {
-		v.v[0xF] = v.v[x] & 7
 		v.v[x] <<= 1
+		v.v[0xF] = v.v[x] & 7
 
 		v.pc += 2
 
@@ -423,6 +426,14 @@ func (v *VM) setAddress() (uint16, error) {
 	return v.opc, nil
 }
 
+// jumpV0 jumps to the address NNN plus V0.
+func (v *VM) jumpV0() (uint16, error) {
+	// Jump to NNN.
+	v.pc = uint16(v.v[0]) + v.opc&0x0FFF
+
+	return v.opc, nil
+}
+
 // setVxRand sets VX to the result of a bitwise and operation on a random
 // number (typically: 0 to 255) and NN.
 func (v *VM) setVxRand() (uint16, error) {
@@ -497,9 +508,9 @@ func (v *VM) skipVxKeyPressed() (uint16, error) {
 	// instead of the usual 2.
 	if v.keys[k] == 1 {
 		v.keys[k] = 0
-		v.pc += 2
-	} else {
 		v.pc += 4
+	} else {
+		v.pc += 2
 	}
 
 	return v.opc & 0xFFFF, nil
@@ -530,23 +541,26 @@ func (v *VM) handle0xF000() (uint16, error) {
 	case 0x0007:
 		return v.getDelayTimer()
 
-	// TODO: FX0A
+	case 0x000A:
+		return v.getKey()
 
 	case 0x0015:
 		return v.setDelayTimer()
 
 	case 0x0018:
 		return v.setSoundTimer()
 
-	// TODO: FX1E
+	case 0x001E:
+		return v.incIVx()
 
 	case 0x0029:
 		return v.loadFont()
 
 	case 0x0033:
 		return v.setBCD()
 
-	// TODO: FX55
+	case 0x0055:
+		return v.regDump()
 
 	case 0x0065:
 		return v.regLoad()
@@ -556,14 +570,29 @@ func (v *VM) handle0xF000() (uint16, error) {
 	}
 }
 
-// getDelayTimer the delay timer to VX.
+// getDelayTimer sets the delay timer to VX.
 func (v *VM) getDelayTimer() (uint16, error) {
 	v.v[(v.opc&0x0F00)>>8] = v.delayTimer
 	v.pc += 2
 
 	return v.opc & 0xFFFF, nil
 }
 
+// getKey waits for a key press and then stores in VX. Blocking Operation. All
+// instruction halted until next key event.
+func (v *VM) getKey() (uint16, error) {
+	x := (v.opc & 0x0F00) >> 8
+	for i := range v.keys {
+		if v.keys[i] == 1 {
+			v.v[x] = v.keys[i]
+			v.pc += 2
+			break
+		}
+	}
+
+	return v.opc & 0xFFFF, nil
+}
+
 // setDelayTimer sets the delay timer to VX.
 func (v *VM) setDelayTimer() (uint16, error) {
 	v.delayTimer = v.v[(v.opc&0x0F00)>>8]
@@ -580,6 +609,14 @@ func (v *VM) setSoundTimer() (uint16, error) {
 	return v.opc & 0xFFFF, nil
 }
 
+// incIVx adds VX to I.
+func (v *VM) incIVx() (uint16, error) {
+	v.i += uint16(v.v[(v.opc&0x0F00)>>8])
+	v.pc += 2
+
+	return v.opc & 0xFFFF, nil
+}
+
 // loadFont sets i to the location of the sprite for the character in VX.
 // Characters 0-F (in hexadecimal) are represented by a 4x5 font.
 func (v *VM) loadFont() (uint16, error) {
@@ -605,7 +642,19 @@ func (v *VM) setBCD() (uint16, error) {
 	return v.opc & 0xFFFF, nil
 }
 
-// fillV0Vx stores V0 to VX (including VX) in mem starting at address i. The
+// regDump 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.
+func (v *VM) regDump() (uint16, error) {
+	for i := uint16(0); i <= (v.opc&0x0F00)>>8; i++ {
+		v.mem[v.i+i] = v.v[i]
+	}
+	v.pc += 2
+
+	return v.opc & 0xFFFF, nil
+}
+
+// regLoad stores V0 to VX (including VX) in mem starting at address i. The
 // offset from i is increased by 1 for each value written, but i itself is left
 // unmodified.
 func (v *VM) regLoad() (uint16, error) {

internal/chip8/vm.go

@@ -129,7 +129,7 @@ func (v *VM) Beep() <-chan struct{} {
 }
 
 // KeyDown marks key as pressed.
-func (v *VM) KeyDown(key uint16) {
+func (v *VM) KeyDown(key byte) {
 	v.keys[key] = 1
 }