protected override void Initialize()
{
Render.Initialize(graphics.GraphicsDevice);
MouseInput.Initialize();
KeyboardInput.Initialize();
base.Initialize();
Console.WriteLine("engine initialized");
cpu.Initialize();
}
protected override void Update(GameTime gameTime)
{
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed || Keyboard.GetState().IsKeyDown(Keys.Escape))
{
Exit();
}
base.Update(gameTime);
cpu.Cycle();
MouseInput.Update();
KeyboardInput.Update();
}
private void Dispatch0x0E(ParsedOpCode parsedOpCode)
{
switch (parsedOpCode.NN)
{
case 0x9E:
// Skip the next instruction if the key mapped to the hex value in register VX is pressed
if (KeyboardInput.IsKeyPressed(CPU.V[parsedOpCode.X]))
{
CPU.ProgramCounter += 2;
}
break;
case 0xA1:
// Skip the next instruction if the key mapped to the hex value in register VX is not pressed
if (!KeyboardInput.IsKeyPressed(CPU.V[parsedOpCode.X]))
{
CPU.ProgramCounter += 2;
}
break;
default:
throw new NotSupportedException();
}
}
private void Dispatch0x0F(ParsedOpCode parsedOpCode)
{
switch (parsedOpCode.NN)
{
case 0x07:
// Store the current value of the delay timer in register VX
CPU.V[parsedOpCode.X] = CPU.DelayTimer.Value;
break;
case 0x0A:
// Wait for a keypress and store the result in register VX
var hexKey = KeyboardInput.WaitForKey();
CPU.V[parsedOpCode.X] = hexKey;
break;
case 0x15:
// Set the delay timer to the value of register VX
CPU.DelayTimer.Value = parsedOpCode.X;
break;
case 0x18:
// Set the sound timer to the value of register VX
CPU.SoundTimer.Value = parsedOpCode.X;
break;
case 0x1E:
// Add the value stored in register VX to register I
CPU.Index += CPU.V[parsedOpCode.X];
break;
case 0x29:
// Set I to the memory address of the sprite data stored in register VX
CPU.Index = (UInt16)(CPU.V[parsedOpCode.X] * 5 + Memory.StartFontLocation);
break;
case 0x33:
// Store the binary-coded decimal equivalent of the value stored in register VX at addresses I, I + 1, and I + 2
var decimalNum = CPU.V[parsedOpCode.X];
Memory[CPU.Index] = (byte)(decimalNum / 100);
Memory[CPU.Index + 1] = (byte)((decimalNum % 100) / 10);
Memory[CPU.Index + 2] = (byte)((decimalNum % 10) % 10);
break;
case 0x55:
// Store the values of registers V0 to VX inclusive in memory starting at address I.
// X + 1 is added to I after completion
for (int i = 0; i <= parsedOpCode.X; i += 1)
{
Memory[CPU.Index + i] = CPU.V[i];
}
CPU.Index += (UInt16)(parsedOpCode.X + 1);
break;
case 0x65:
// Fill registers V0 to VX inclusive with the values stored in memory starting at address I
// X + 1 is added to I after operation
for (int i = 0; i <= parsedOpCode.X; i += 1)
{
CPU.V[i] = Memory[CPU.Index + i];
}
CPU.Index += (UInt16)(parsedOpCode.X + 1);
break;
default:
throw new NotSupportedException();
}
}
