public void Executing_Instruction_Dxy0_DoesNotUseDisplay()
{
var cpu = new Cpu();
var decodedInstruction = new DecodedInstruction(0xD230);
var instruction = new Instruction_Dxyn(decodedInstruction);
instruction.Execute(cpu, MockedDisplay, MockedKeyboard);
}
public void Executing_Instruction_Dxyn_WorksAsExpected()
{
const byte xCoordinate = 0x5, yCoordinate = 0x6;
var cpu = new Cpu();
cpu.V[2] = xCoordinate;
cpu.V[3] = yCoordinate;
cpu.I = 0x300;
cpu.Memory[cpu.I] = 0x1;
var decodedInstruction = new DecodedInstruction(0xD231);
// Expected execution result:
// - decodedInstruction.n bytes (1) are read from memory, starting at location I (0x300)
// - those bytes are written to screen, starting at location (V2, V3) = 5,6
// - since value at 0x300 is 0x1, and 1 is the least significant bit of that byte, then location where
// pixel will be set is: xCoordinate + 7 (e.g. for value of 2, it would be xCoordinate + 6)
// - re-executing the same command will reset the pixel and set VF register to 1
var mockSequence = new MockSequence();
var displayMock = new Mock<IDisplay>(MockBehavior.Strict);
// First execution
for(byte i = 0; i < 8; i++)
{
displayMock.InSequence(mockSequence).Setup(x => x.GetPixel(
(byte)(xCoordinate + i), yCoordinate)).Returns(false);
}
displayMock.InSequence(mockSequence).Setup(x => x.SetPixel(xCoordinate + 7, yCoordinate));
// Second execution
for (byte i = 0; i < 8; i++)
{
displayMock.InSequence(mockSequence).Setup(x => x.GetPixel(
(byte)(xCoordinate + i), yCoordinate)).Returns(i == 7);
}
displayMock.InSequence(mockSequence).Setup(x => x.ClearPixel(xCoordinate + 7, yCoordinate));
var display = displayMock.Object;
var instruction = new Instruction_Dxyn(decodedInstruction);
instruction.Execute(cpu, display, MockedKeyboard);
Assert.That(cpu.V[0xF], Is.EqualTo(0));
instruction.Execute(cpu, display, MockedKeyboard);
Assert.That(cpu.V[0xF], Is.EqualTo(1));
displayMock.VerifyAll();
Assert.That(instruction.Mnemonic, Is.EqualTo($"DRW V{decodedInstruction.x:X}, V{decodedInstruction.y:X}, {decodedInstruction.n:X}"));
}
/// <summary>
/// Converts instance of <see cref="DecodedInstruction"/> into an instance of <see cref="CpuInstruction"/>.
/// </summary>
/// <param name="decodedInstruction">Decoded 2 bytes of memory.</param>
/// <returns>Concrete Cpu instruction or <see cref="UndefinedInstruction"/> if instruction cannot be determined.</returns>
public CpuInstruction GetCpuInstruction(DecodedInstruction decodedInstruction)
{
CpuInstruction cpuInstruction = null;
switch (decodedInstruction.OpCode)
{
case 0x0:
if (decodedInstruction.kk == 0xE0)
{
cpuInstruction = new Instruction_00E0(decodedInstruction);
}
else if (decodedInstruction.kk == 0xEE)
{
cpuInstruction = new Instruction_00EE(decodedInstruction);
}
break;
case 0x1:
cpuInstruction = new Instruction_1nnn(decodedInstruction);
break;
case 0x2:
cpuInstruction = new Instruction_2nnn(decodedInstruction);
break;
case 0x3:
cpuInstruction = new Instruction_3xkk(decodedInstruction);
break;
case 0x4:
cpuInstruction = new Instruction_4xkk(decodedInstruction);
break;
case 0x5:
if (decodedInstruction.n == 0x0)
{
cpuInstruction = new Instruction_5xy0(decodedInstruction);
}
break;
case 0x6:
cpuInstruction = new Instruction_6xkk(decodedInstruction);
break;
case 0x7:
cpuInstruction = new Instruction_7xkk(decodedInstruction);
break;
case 0x8:
{
switch (decodedInstruction.n)
{
case 0x0:
cpuInstruction = new Instruction_8xy0(decodedInstruction);
break;
case 0x1:
cpuInstruction = new Instruction_8xy1(decodedInstruction);
break;
case 0x2:
cpuInstruction = new Instruction_8xy2(decodedInstruction);
break;
case 0x3:
cpuInstruction = new Instruction_8xy3(decodedInstruction);
break;
case 0x4:
cpuInstruction = new Instruction_8xy4(decodedInstruction);
break;
case 0x5:
cpuInstruction = new Instruction_8xy5(decodedInstruction);
break;
case 0x6:
cpuInstruction = new Instruction_8xy6(decodedInstruction);
break;
case 0x7:
cpuInstruction = new Instruction_8xy7(decodedInstruction);
break;
case 0xE:
cpuInstruction = new Instruction_8xyE(decodedInstruction);
break;
default:
cpuInstruction = new UndefinedInstruction(decodedInstruction);
break;
}
}
break;
case 0x9:
if (decodedInstruction.n == 0x0)
{
cpuInstruction = new Instruction_9xy0(decodedInstruction);
}
break;
case 0xA:
cpuInstruction = new Instruction_Annn(decodedInstruction);
break;
case 0xB:
cpuInstruction = new Instruction_Bnnn(decodedInstruction);
break;
case 0xC:
cpuInstruction = new Instruction_Cxkk(decodedInstruction);
break;
case 0xD:
cpuInstruction = new Instruction_Dxyn(decodedInstruction);
break;
case 0xE:
{
switch (decodedInstruction.kk)
{
case 0x9E:
cpuInstruction = new Instruction_Ex9E(decodedInstruction);
break;
case 0xA1:
cpuInstruction = new Instruction_ExA1(decodedInstruction);
break;
default:
cpuInstruction = new UndefinedInstruction(decodedInstruction);
break;
}
}
break;
case 0xF:
{
switch (decodedInstruction.kk)
{
case 0x07:
cpuInstruction = new Instruction_Fx07(decodedInstruction);
break;
case 0x0A:
cpuInstruction = new Instruction_Fx0A(decodedInstruction);
break;
case 0x15:
cpuInstruction = new Instruction_Fx15(decodedInstruction);
break;
case 0x18:
cpuInstruction = new Instruction_Fx18(decodedInstruction);
break;
case 0x1E:
cpuInstruction = new Instruction_Fx1E(decodedInstruction);
break;
case 0x29:
cpuInstruction = new Instruction_Fx29(decodedInstruction);
break;
case 0x33:
cpuInstruction = new Instruction_Fx33(decodedInstruction);
break;
case 0x55:
cpuInstruction = new Instruction_Fx55(decodedInstruction);
break;
case 0x65:
cpuInstruction = new Instruction_Fx65(decodedInstruction);
break;
default:
cpuInstruction = new UndefinedInstruction(decodedInstruction);
break;
}
break;
}
default:
cpuInstruction = new UndefinedInstruction(decodedInstruction);
break;
}
return(cpuInstruction ?? new UndefinedInstruction(decodedInstruction));
}
