/// <summary>
/// test BITs
/// </summary>
private static void Bit(Cpu cpu, InstructionData data)
{
var value = cpu.ReadByte(data.ArgumentAddress);
cpu.SetFlag(CpuFlags.Overflow, ((value >> 6) & 1) != 0);
cpu.SetZero((byte)(value & cpu.accumulator));
cpu.SetNegative(value);
}
/// <summary>
/// Load Accumulator and X register
/// </summary>
private static void Lax(Cpu cpu, InstructionData data)
{
var value = cpu.ReadByte(data.ArgumentAddress);
cpu.accumulator = value;
cpu.x = value;
cpu.SetZeroNegative(value);
}
/// <summary>
/// ADd with Carry
/// </summary>
private static void Adc(Cpu cpu, InstructionData data)
{
var a = cpu.accumulator;
var b = cpu.ReadByte(data.ArgumentAddress);
var c = cpu.GetFlag(CpuFlags.Carry) ? 1 : 0;
var result = a + b + c;
cpu.accumulator = (byte)result;
cpu.SetZeroNegative(cpu.accumulator);
cpu.SetFlag(CpuFlags.Carry, result > 0xff);
cpu.SetFlag(CpuFlags.Overflow, (((a ^ b) & 0x80) == 0) && (((a ^ cpu.accumulator) & 0x80) != 0));
}
/// <summary>
/// ROtate Right
/// </summary>
private static void Ror(Cpu cpu, InstructionData data)
{
if (data.AddressingMode == AddressingMode.Accumulator)
{
cpu.RotateRight(ref cpu.accumulator);
}
else
{
var value = cpu.ReadByte(data.ArgumentAddress);
cpu.RotateRight(ref value);
cpu.WriteByte(data.ArgumentAddress, value);
}
}
/// <summary>
/// SuBtract with Carry
/// </summary>
private static void Sbc(Cpu cpu, InstructionData data)
{
var a = cpu.accumulator;
var b = cpu.ReadByte(data.ArgumentAddress);
var result = a - b;
if (!cpu.GetFlag(CpuFlags.Carry))
{
result -= 1;
}
cpu.accumulator = (byte)result;
cpu.SetZeroNegative(cpu.accumulator);
cpu.SetFlag(CpuFlags.Carry, result >= 0);
cpu.SetFlag(CpuFlags.Overflow, (((a ^ b) & 0x80) != 0) && (((a ^ cpu.accumulator) & 0x80) != 0));
}
public bool Advance()
{
if (waitCycles > 0)
{
waitCycles--;
return(false);
}
var log = new StringBuilder();
log.Append($"0x{programCounter:X4}");
var opCode = ReadByte(programCounter);
var instruction = Instructions[opCode];
var adressingMode = InstructionAdressingModes[opCode];
var instructionData = new InstructionData
{
ArgumentAddress = GetInstructionArgumentAddress(adressingMode),
ProgramCounter = programCounter,
AddressingMode = adressingMode
};
var instructionSize = GetInstructionSize(adressingMode);
for (int i = 0; i < 3; i++)
{
if (i <= instructionSize)
{
log.Append($" {ReadByte((ushort) (programCounter + i)):X2}");
}
else
{
log.Append(" ");
}
}
programCounter += instructionSize;
waitCycles = InstructionCycles[opCode];
if (IsPageCrossed(adressingMode, instructionData.ArgumentAddress))
{
waitCycles += InstructionPageCrossCycles[opCode];
}
log.Append($" {opCode:X2} {instruction.Method.Name.ToUpper()} {adressingMode} 0x{instructionData.ArgumentAddress:X4}");
instruction(this, instructionData);
System.Console.Out.WriteLine(log.ToString());
return(true);
}
/// <summary>
/// Jump to SubRoutine
/// </summary>
private static void Jsr(Cpu cpu, InstructionData data)
{
cpu.PushShort((ushort)(cpu.programCounter - 1));
cpu.programCounter = data.ArgumentAddress;
}
/// <summary>
/// PuLl Processor status
/// </summary>
private static void Plp(Cpu cpu, InstructionData data)
{
cpu.flags = (CpuFlags)(cpu.PullByte() & 0xEF | 0x20);
}
/// <summary>
/// STore Y register
/// </summary>
private static void Sty(Cpu cpu, InstructionData data)
{
cpu.Store(data.ArgumentAddress, cpu.y);
}
/// <summary>
/// Rotate Right, then Add memory to accumulator with carry
/// </summary>
private static void Rra(Cpu cpu, InstructionData data)
{
Ror(cpu, data);
Adc(cpu, data);
}
/// <summary>
/// Transfer Y to A
/// </summary>
private static void Tya(Cpu cpu, InstructionData data)
{
cpu.Transfer(cpu.y, out cpu.accumulator);
}
/// <summary>
/// Increment memory and Subtract with Carry
/// </summary>
private static void Isb(Cpu cpu, InstructionData data)
{
Inc(cpu, data);
Sbc(cpu, data);
}
/// <summary>
/// Rotate Left then And accumulator with memory
/// </summary>
private static void Rla(Cpu cpu, InstructionData data)
{
Rol(cpu, data);
And(cpu, data);
}
/// <summary>
/// STore Accumulator
/// </summary>
private static void Sta(Cpu cpu, InstructionData data)
{
cpu.Store(data.ArgumentAddress, cpu.accumulator);
}
/// <summary>
/// Transfer X to Stack ptr
/// </summary>
private static void Txs(Cpu cpu, InstructionData data)
{
cpu.stackPointer = cpu.x;
}
/// <summary>
/// ReTurn from Subroutine
/// </summary>
private static void Rts(Cpu cpu, InstructionData data)
{
cpu.programCounter = (ushort)(cpu.PullShort() + 1);
}
/// <summary>
/// LoaD Y register
/// </summary>
private static void Ldy(Cpu cpu, InstructionData data)
{
cpu.Load(out cpu.y, data.ArgumentAddress);
}
/// <summary>
/// No OPeration
/// </summary>
private static void Nop(Cpu cpu, InstructionData data)
{
}
/// <summary>
/// INcrement Y
/// </summary>
private static void Iny(Cpu cpu, InstructionData data)
{
cpu.Increment(ref cpu.y);
}
/// <summary>
/// DEcrement Y
/// </summary>
private static void Dey(Cpu cpu, InstructionData data)
{
cpu.Decrement(ref cpu.y);
}
/// <summary>
/// Store Accumulator and X register
/// </summary>
private static void Sax(Cpu cpu, InstructionData data)
{
cpu.Store(data.ArgumentAddress, (byte)(cpu.accumulator & cpu.x));
}
/// <summary>
/// LoaD Accumulator
/// </summary>
private static void Lda(Cpu cpu, InstructionData data)
{
cpu.Load(out cpu.accumulator, data.ArgumentAddress);
}
/// <summary>
/// Decrease memory and ComPare with accumulator
/// </summary>
private static void Dcp(Cpu cpu, InstructionData data)
{
Dec(cpu, data);
Cmp(cpu, data);
}
/// <summary>
/// PusH Accumulator
/// </summary>
private static void Pha(Cpu cpu, InstructionData data)
{
cpu.PushByte(cpu.accumulator);
}
/// <summary>
/// arithmetic Shift Left then Or accumulator with memory
/// </summary>
private static void Slo(Cpu cpu, InstructionData data)
{
Asl(cpu, data);
Ora(cpu, data);
}
/// <summary>
/// PuLl Accumulator
/// </summary>
private static void Pla(Cpu cpu, InstructionData data)
{
cpu.accumulator = cpu.PullByte();
cpu.SetZeroNegative(cpu.accumulator);
}
/// <summary>
/// logical Shift Right then Eor accumulator with memory
/// </summary>
private static void Sre(Cpu cpu, InstructionData data)
{
Lsr(cpu, data);
Eor(cpu, data);
}
/// <summary>
/// PusH Processor status
/// </summary>
private static void Php(Cpu cpu, InstructionData data)
{
cpu.PushByte((byte)((byte)cpu.flags | 0x10));
}
/// <summary>
/// Transfer Stack ptr to X
/// </summary>
private static void Tsx(Cpu cpu, InstructionData data)
{
cpu.x = cpu.stackPointer;
cpu.SetZeroNegative(cpu.x);
}
/// <summary>
/// bitwise OR with Accumulator
/// </summary>
private static void Ora(Cpu cpu, InstructionData data)
{
cpu.accumulator = (byte)(cpu.accumulator | cpu.ReadByte(data.ArgumentAddress));
cpu.SetZeroNegative(cpu.accumulator);
}