protected override void InternalExecute(CpuState cpuState, IMemory memory, byte arg, Action<byte> write, ref int cycles)
{
bool carry = cpuState.IsFlagSet(CpuState.Flags.Carry);
cpuState.SetFlag(CpuState.Flags.Carry, arg & 0x80);
arg <<= 1;
if (carry)
{
arg |= 1;
}
write(arg);
cpuState.SetNegativeFlag(arg);
cpuState.SetZeroFlag(arg);
switch (Variants[memory[cpuState.Pc]])
{
case AddressingMode.Accumulator:
cycles = 2;
break;
case AddressingMode.ZeroPage:
cycles = 5;
break;
case AddressingMode.ZeroPageXIndexed:
cycles = 6;
break;
case AddressingMode.Absolute:
cycles = 6;
break;
case AddressingMode.AbsoluteX:
cycles = 7;
break;
}
}
protected override void InternalExecute(CpuState cpuState, IMemory memory, byte arg, Action<byte> write, ref int cycles)
{
var breakSet = cpuState.IsFlagSet(CpuState.Flags.Break);
cpuState.StatusRegister = cpuState.PopStack(memory);
cpuState.StatusRegister |= 1 << 5;
cpuState.SetFlag(CpuState.Flags.Break, breakSet);
cycles = 4;
}
public int Execute(CpuState cpuState, IMemory memory)
{
var breakSet = cpuState.IsFlagSet(CpuState.Flags.Break);
cpuState.StatusRegister = cpuState.PopStack(memory);
cpuState.SetFlag(CpuState.Flags.Break, breakSet);
cpuState.StatusRegister |= 1 << 5;
var low = cpuState.PopStack(memory);
var high = cpuState.PopStack(memory);
cpuState.Pc = (ushort)((high << 8) | low);
return 6;
}
protected override void InternalExecute(CpuState cpuState, IMemory memory, byte arg, Action<byte> write, ref int cycles)
{
var sum = (ushort) (arg + cpuState.A);
if (cpuState.IsFlagSet(CpuState.Flags.Carry))
{
++sum;
}
var byteSum = (byte)(sum & 0xFF);
cpuState.SetOverflow(cpuState.A, arg, byteSum);
cpuState.A = byteSum;
cpuState.SetZeroFlag(cpuState.A);
cpuState.SetNegativeFlag(cpuState.A);
cpuState.SetFlag(CpuState.Flags.Carry, sum & 0xFF00);
}
protected override void InternalExecute(CpuState cpuState, IMemory memory, byte arg, Action<byte> write, ref int cycles)
{
// A - M - C -> A N Z C I D V
// + + + - - +
int a = cpuState.A;
arg ^= 0xFF;
a += arg;
if (cpuState.IsFlagSet(CpuState.Flags.Carry))
{
++a;
}
var byteResult = (byte) (a & 0xFF);
cpuState.SetOverflow(cpuState.A, arg, byteResult);
cpuState.A = byteResult;
cpuState.SetNegativeFlag(cpuState.A);
cpuState.SetZeroFlag(cpuState.A);
cpuState.SetFlag(CpuState.Flags.Carry, (byteResult & 0x80) == 0);
}
protected override bool ShouldBranch(CpuState cpuState, IMemory memory)
{
return cpuState.IsFlagSet(CpuState.Flags.Negative);
}
protected override bool ShouldBranch(CpuState cpuState, IMemory memory)
{
return !cpuState.IsFlagSet(CpuState.Flags.Zero);
}