public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
void @out(byte portNumber, ByteRegister dataRegister, bool bc)
{
Port port = cpu.Ports[portNumber];
byte output = 0;
if (dataRegister != ByteRegister.None)
{
output = r[dataRegister];
}
port.SignalWrite();
port.WriteByte(output, bc);
}
if (instruction.Prefix == 0x00)
{
// OUT (n),A
r.WZ = (ushort)((r.A << 8) + data.Argument1 + 1);
@out(data.Argument1, ByteRegister.A, false);
}
else
{
// OUT (C),r
@out(r.C, instruction.Source.AsByteRegister(), true);
r.WZ = (ushort)(r.BC + 1);
}
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
Port port = cpu.Ports[r.C];
port.SignalRead();
byte input = port.ReadByte(true);
cpu.Memory.Timed.WriteByteAt(r.HL, input);
cpu.Timing.InternalOperationCycle(5);
r.HL--;
r.WZ = r.BC;
r.B--;
flags.Zero = true;
flags.Subtract = true;
flags.X = (input & 0x08) > 0; // copy bit 3
flags.Y = (input & 0x20) > 0; // copy bit 5
if (r.B != 0)
{
r.PC = package.InstructionAddress;
}
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
switch (instruction.Opcode)
{
case 0x46:
case 0x4E:
case 0x66: // IM 0
cpu.SetInterruptMode(InterruptMode.IM0);
break;
case 0x56:
case 0x76: // IM 1
cpu.SetInterruptMode(InterruptMode.IM1);
break;
case 0x5E:
case 0x7E: // IM 2
cpu.SetInterruptMode(InterruptMode.IM2);
break;
}
return(new ExecutionResult(package, null));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
byte value = cpu.Memory.Timed.ReadByteAt(r.HL);
cpu.Memory.Timed.WriteByteAt(r.DE, value);
r.HL++;
r.DE++;
r.BC--;
flags.HalfCarry = false;
flags.ParityOverflow = (r.BC != 0);;
flags.Subtract = false;
flags.X = (((byte)(value + cpu.Registers.A)) & 0x08) > 0; // copy bit 3
flags.Y = (((byte)(value + cpu.Registers.A)) & 0x02) > 0; // copy bit 1 (note: non-standard behaviour)
bool conditionTrue = (r.BC == 0);
if (conditionTrue)
{
cpu.Timing.InternalOperationCycle(5);
r.WZ = (ushort)(r.PC + 1);
}
else
{
r.PC = package.InstructionAddress;
}
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
cpu.Pop(WordRegister.PC);
cpu.Registers.WZ = cpu.Registers.PC;
cpu.RestoreInterruptsFromNMI(); // will re-enable maskable interrupts if they were enabled before entering the NMI handler
return(new ExecutionResult(package, null));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Registers r = cpu.Registers;
if (instruction.Opcode == 0x08)
{
// EX AF,AF'
r.ExchangeAF();
}
else
{
if (instruction.Target == InstructionElement.AddressFromSP)
{
// EX (SP),HL/IX/IY
ushort value = instruction.MarshalSourceWord(data, cpu, out ushort address);
ushort valueAtSP = cpu.Memory.Untimed.ReadWordAt(r.SP);
r[instruction.Source.AsWordRegister()] = valueAtSP;
cpu.Memory.Timed.WriteWordAt(r.SP, value);
r.WZ = valueAtSP;
}
else
{
// EX DE,HL
ushort de = r.DE;
r.DE = r.HL;
r.HL = de;
}
}
return(new ExecutionResult(package, null));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
if (instruction.TargetsWordRegister)
{
ushort left = r.HL;
cpu.Timing.InternalOperationCycle(4);
cpu.Timing.InternalOperationCycle(3);
ushort right = instruction.MarshalSourceWord(data, cpu, out ushort address);
var addition = ALUOperations.Add(left, right, flags.Carry, true, flags);
r.HL = addition.Result;
flags = addition.Flags;
r.WZ = (ushort)(left + 1);
}
else
{
byte left = r.A;
if (instruction.IsIndexed)
{
cpu.Timing.InternalOperationCycle(5);
}
byte right = instruction.MarshalSourceByte(data, cpu, out ushort address, out ByteRegister source);
var addition = ALUOperations.Add(left, right, flags.Carry);
r.A = addition.Result;
flags = addition.Flags;
}
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
Port port = cpu.Ports[r.C];
byte output = cpu.Memory.Timed.ReadByteAt(r.HL);
r.WZ = r.BC;
r.B--;
port.SignalWrite();
port.WriteByte(output, true);
r.HL++;
flags.Zero = true;
flags.Subtract = true;
flags.X = (output & 0x08) > 0; // copy bit 3
flags.Y = (output & 0x20) > 0; // copy bit 5
if (r.B != 0)
{
r.PC = package.InstructionAddress;
}
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
bool carry = flags.Carry;
byte a = cpu.Registers.A;
byte b = cpu.Memory.Timed.ReadByteAt(cpu.Registers.HL);
var compare = ALUOperations.Subtract(a, b, false);
flags = compare.Flags;
cpu.Registers.BC--;
flags.ParityOverflow = (cpu.Registers.BC != 0);
cpu.Registers.HL--;
flags.Subtract = true;
flags.Carry = carry;
byte valueXY = (byte)(a - b - (flags.HalfCarry ? 1 : 0));
flags.X = (valueXY & 0x08) > 0; // copy bit 3
flags.Y = (valueXY & 0x02) > 0; // copy bit 1 (note: non-standard behaviour)
cpu.Registers.WZ++;
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
if (instruction.Condition == Condition.None || cpu.Flags.SatisfyCondition(instruction.Condition))
{
cpu.Timing.InternalOperationCycle(5);
ushort address = (ushort)(cpu.Registers.PC - 2); // wind back to the address of the JR instruction as PC has already moved on
// the jump is relative to the address of the JR instruction but the jump *displacement* is calculated from the start of the *next* instruction.
// This means the actual jump range is -126 to +129 bytes, *not* 127 bytes each way. Z80 assemblers compensate for this by
// adjusting the jump value, so for example 'JR 0' would actually end up being 'JR 2' and would set PC to the start of the next
// instruction - hence we must add two bytes here to resolve the correct target address
address = (ushort)(address + (sbyte)data.Argument1 + 2);
cpu.Registers.PC = address;
cpu.Flags.X = (address & 0x08) > 0; // copy bit 3
cpu.Flags.Y = (address & 0x20) > 0; // copy bit 5
cpu.Registers.WZ = address;
}
return(new ExecutionResult(package, cpu.Flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
cpu.Halt(HaltReason.HaltInstruction);
return(new ExecutionResult(package, null));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
WordRegister register = instruction.Target.AsWordRegister();
cpu.Pop(register);
return(new ExecutionResult(package, null));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
sbyte offset = (sbyte)(data.Argument1);
ByteRegister register = instruction.Target.AsByteRegister();
bool previousCarry = flags.Carry;
byte original, shifted;
if (register != ByteRegister.None)
{
original = r[register];
shifted = (byte)(original >> 1);
shifted = shifted.SetBit(7, previousCarry);
setFlags(original, shifted, original.GetBit(0));
r[register] = shifted;
}
else
{
ushort address = instruction.Prefix switch
{
0xCB => r.HL,
0xDDCB => (ushort)(r.IX + offset),
0xFDCB => (ushort)(r.IY + offset),
_ => (ushort)0xFFFF
};
original = cpu.Memory.Timed.ReadByteAt(address);
shifted = (byte)(original >> 1);
shifted = shifted.SetBit(7, previousCarry);
setFlags(original, shifted, original.GetBit(0));
if (instruction.IsIndexed)
{
cpu.Timing.InternalOperationCycle(4);
}
cpu.Memory.Timed.WriteByteAt(address, shifted);
if (instruction.CopyResultTo != ByteRegister.None)
{
r[instruction.CopyResultTo.Value] = shifted;
}
}
void setFlags(byte original, byte shifted, bool overflowBit)
{
flags = FlagLookup.BitwiseFlags(original, BitwiseOperation.RotateRightThroughCarry, previousCarry);
flags.Carry = overflowBit;
flags.HalfCarry = false;
flags.Subtract = false;
}
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
byte A = r.A;
int mode = 0;
if ((A & 0x0F) > 0x09 || flags.HalfCarry)
{
mode++;
}
if (A > 0x99 || flags.Carry)
{
mode += 2;
flags.Carry = true;
}
if (flags.Subtract && !flags.HalfCarry)
{
flags.HalfCarry = false;
}
else
{
if (flags.Subtract && flags.HalfCarry)
{
flags.HalfCarry = (A & 0x0F) < 0x06;
}
else
{
flags.HalfCarry = (A & 0x0F) >= 0x0A;
}
}
A = mode switch
{
1 => (byte)(A + (byte)(flags.Subtract ? 0xFA : 0x06)),
2 => (byte)(A + (byte)(flags.Subtract ? 0xA0 : 0x60)),
3 => (byte)(A + (byte)(flags.Subtract ? 0x9A : 0x66)),
_ => A
};
flags.Sign = (A & 0x80) > 0;
flags.Zero = (A == 0);
flags.ParityOverflow = A.EvenParity();
flags.X = (A & 0x08) > 0; // copy bit 3
flags.Y = (A & 0x20) > 0; // copy bit 5
r.A = A;
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Flags flags = cpu.Flags;
flags.Carry = true;
flags.HalfCarry = false;
flags.Subtract = false;
flags.X = (cpu.Registers.A & 0x08) > 0; // copy bit 3
flags.Y = (cpu.Registers.A & 0x20) > 0; // copy bit 5
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
if (instruction.Condition == Condition.None || flags.SatisfyCondition(instruction.Condition))
{
cpu.Pop(WordRegister.PC);
cpu.Registers.WZ = cpu.Registers.PC;
}
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
byte t_index = instruction.Opcode.GetByteFromBits(3, 3);
ushort address = (ushort)(t_index * 8);
cpu.Push(WordRegister.PC);
cpu.Registers.PC = (address);
cpu.Registers.WZ = cpu.Registers.PC;
return(new ExecutionResult(package, null));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Registers r = cpu.Registers;
Flags flags = cpu.Flags;
int result = 0x00 - r.A;
flags = FlagLookup.ByteArithmeticFlags(0x00, r.A, false, true);
flags.ParityOverflow = r.A == 0x80;
flags.Carry = r.A != 0x00;
r.A = (byte)result;
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
sbyte offset = (sbyte)(data.Argument1);
ByteRegister register = instruction.Target.AsByteRegister();
void setFlags(byte original)
{
flags = FlagLookup.BitwiseFlags(original, BitwiseOperation.ShiftLeftSetBit0, flags.Carry);
flags.Carry = original.GetBit(7);
flags.HalfCarry = false;
flags.Subtract = false;
}
byte original, shifted;
if (register != ByteRegister.None)
{
original = r[register];
shifted = (byte)((original << 1) + 1); // bit 0 is always set, adding 1 does this quicker than calling SetBit
setFlags(original);
r[register] = shifted;
}
else
{
ushort address = instruction.Prefix switch
{
0xCB => r.HL,
0xDDCB => (ushort)(r.IX + offset),
0xFDCB => (ushort)(r.IY + offset),
_ => (ushort)0xFFFF
};
original = cpu.Memory.Timed.ReadByteAt(address);
shifted = (byte)((original << 1) + 1);
setFlags(original);
cpu.Memory.Timed.WriteByteAt(address, shifted);
if (instruction.CopyResultTo != ByteRegister.None)
{
r[instruction.CopyResultTo.Value] = shifted;
}
}
return new ExecutionResult(package, flags);
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Registers r = cpu.Registers;
byte offset = data.Argument1;
Flags flags = cpu.Flags;
if (instruction.TargetsWordRegister)
{
// inc 16-bit
WordRegister register = instruction.Target.AsWordRegister();
ushort value = r[register];
r[register] = (ushort)(value + 1);
}
else
{
byte value = 0;
if (instruction.TargetsByteInMemory)
{
// inc byte in memory
if (instruction.IsIndexed)
{
cpu.Timing.InternalOperationCycle(5);
}
value = instruction.MarshalSourceByte(data, cpu, out ushort address, out ByteRegister source);
cpu.Memory.Timed.WriteByteAt(address, (byte)(value + 1));
}
else
{
// it's an 8-bit inc
ByteRegister register = instruction.Target.AsByteRegister();
value = r[register];
r[register] = (byte)(value + 1);
}
bool carry = flags.Carry;
flags = FlagLookup.ByteArithmeticFlags(value, 1, false, false);
flags.ParityOverflow = (value == 0x7F);
flags.Carry = carry; // always unaffected
flags.Subtract = false;
}
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Registers r = cpu.Registers;
Flags flags = cpu.Flags;
byte bitIndex = instruction.GetBitIndex();
byte value;
ByteRegister register = instruction.Source.AsByteRegister();
if (register != ByteRegister.None)
{
value = r[register]; // BIT b, r
}
else
{
if (instruction.IsIndexed)
{
cpu.Timing.InternalOperationCycle(5);
}
value = instruction.MarshalSourceByte(data, cpu, out ushort address, out ByteRegister source);
byte valueXY = instruction.IsIndexed ? address.HighByte() : r.WZ.HighByte(); // this is literally the only place the WZ value is *ever* actually used
flags.X = (valueXY & 0x08) > 0; // copy bit 3
flags.Y = (valueXY & 0x20) > 0; // copy bit 5
}
bool set = value.GetBit(bitIndex);
flags.Sign = bitIndex == 7 && set;
if (register == ByteRegister.None)
{
flags.Y = bitIndex == 5 && set;
flags.X = bitIndex == 3 && set;
}
flags.Zero = !set;
flags.ParityOverflow = flags.Zero;
flags.HalfCarry = true;
flags.Subtract = false;
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
if (instruction.Source != InstructionElement.WordValue)
{
// JP HL / IX / IY
cpu.Registers.PC = instruction.MarshalSourceWord(data, cpu, out ushort address);
}
else if (instruction.Condition == Condition.None || flags.SatisfyCondition(instruction.Condition))
{
cpu.Registers.PC = data.ArgumentsAsWord;
cpu.Registers.WZ = data.ArgumentsAsWord;
}
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
if (instruction.IsIndexed)
{
cpu.Timing.InternalOperationCycle(5);
}
byte operand = instruction.MarshalSourceByte(data, cpu, out ushort address, out ByteRegister source);
int result = (r.A | operand);
flags = FlagLookup.LogicalFlags(r.A, operand, LogicalOperation.Or);
r.A = (byte)result;
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
byte @in(byte portNumber, ByteRegister toRegister, bool bc)
{
Port port = cpu.Ports[portNumber];
port.SignalRead();
byte input = port.ReadByte(bc);
if (toRegister != ByteRegister.F)
{
r[toRegister] = input;
}
return(input);
}
if (instruction.Prefix == 0x00)
{
// IN A,(n)
r.WZ = (ushort)((r.A << 8) + data.Argument1 + 1);
@in(data.Argument1, ByteRegister.A, false);
}
else
{
// IN r,(C)
byte input = @in(r.C, instruction.Target.AsByteRegister(), true);
flags.Sign = ((sbyte)input < 0);
flags.Zero = (input == 0);
flags.ParityOverflow = input.EvenParity();
flags.HalfCarry = false;
flags.Subtract = false;
flags.X = (input & 0x08) > 0; // copy bit 3
flags.Y = (input & 0x20) > 0; // copy bit 5
r.WZ = (ushort)(r.BC + 1);
}
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
bool carry = flags.Carry;
byte a = cpu.Registers.A;
byte b = cpu.Memory.Timed.ReadByteAt(cpu.Registers.HL);
var compare = ALUOperations.Subtract(a, b, false);
flags = compare.Flags;
cpu.Registers.BC--;
flags.ParityOverflow = (cpu.Registers.BC != 0);
cpu.Registers.HL++;
flags.Subtract = true;
flags.Carry = carry;
byte valueXY = (byte)(a - b - (flags.HalfCarry ? 1 : 0));
flags.X = (valueXY & 0x08) > 0; // copy bit 3
flags.Y = (valueXY & 0x02) > 0; // copy bit 1 (note: non-standard behaviour)
bool conditionTrue = (compare.Result == 0 || cpu.Registers.BC == 0);
if (conditionTrue)
{
cpu.Timing.InternalOperationCycle(5);
cpu.Registers.WZ++;
}
else
{
cpu.Registers.PC = package.InstructionAddress;
cpu.Registers.WZ = (ushort)(cpu.Registers.PC + 1);
}
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
byte value = r.A;
flags.Carry = value.GetBit(0);
value = (byte)(value >> 1);
value = value.SetBit(7, flags.Carry);
flags.HalfCarry = false;
flags.Subtract = false;
flags.X = (value & 0x08) > 0; // copy bit 3
flags.Y = (value & 0x20) > 0; // copy bit 5
r.A = value;
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
byte left = r.A;
byte right = instruction.MarshalSourceByte(data, cpu, out ushort address, out ByteRegister source);
if (instruction.IsIndexed)
{
cpu.Timing.InternalOperationCycle(5);
}
var sub = ALUOperations.Subtract(left, right, false);
r.A = sub.Result;
flags = sub.Flags;
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Registers r = cpu.Registers;
byte bitIndex = instruction.GetBitIndex();
sbyte offset = (sbyte)(data.Argument1);
ByteRegister register = instruction.Source.AsByteRegister();
if (register != ByteRegister.None)
{
byte value = r[register].SetBit(bitIndex, true);
r[register] = value;
}
else
{
ushort address = instruction.Prefix switch
{
0xCB => r.HL,
0xDDCB => (ushort)(r.IX + offset),
0xFDCB => (ushort)(r.IY + offset),
_ => (ushort)0xFFFF
};
if (instruction.IsIndexed)
{
cpu.Timing.InternalOperationCycle(5);
}
byte value = cpu.Memory.Timed.ReadByteAt(address);
value = value.SetBit(bitIndex, true);
cpu.Memory.Timed.WriteByteAt(address, value);
if (instruction.CopyResultTo != ByteRegister.None)
{
r[instruction.CopyResultTo.Value] = value;
}
}
return(new ExecutionResult(package, null));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
byte value = cpu.Memory.Timed.ReadByteAt(r.HL);
cpu.Memory.Timed.WriteByteAt(r.DE, value);
r.HL++;
r.DE++;
r.BC--;
flags.HalfCarry = false;
flags.ParityOverflow = (r.BC != 0);
flags.Subtract = false;
flags.X = (((byte)(value + cpu.Registers.A)) & 0x08) > 0; // copy bit 3
flags.Y = (((byte)(value + cpu.Registers.A)) & 0x02) > 0; // copy bit 1 (note: non-standard behaviour)
return(new ExecutionResult(package, flags));
}
public ExecutionResult Execute(Processor cpu, InstructionPackage package)
{
Instruction instruction = package.Instruction;
InstructionData data = package.Data;
Flags flags = cpu.Flags;
Registers r = cpu.Registers;
if (instruction.TargetsWordRegister)
{
// it's one of the 16-bit adds (HL,DE etc)
WordRegister destination = instruction.Target.AsWordRegister();
ushort left = r[destination];
ushort right = instruction.MarshalSourceWord(data, cpu, out ushort address);
cpu.Timing.InternalOperationCycle(4);
cpu.Timing.InternalOperationCycle(3);
var sum = ALUOperations.Add(left, right, false, false, flags);
r[destination] = sum.Result;
flags = sum.Flags;
r.WZ = (ushort)(left + 1);
}
else
{
// it's an 8-bit add to A
byte left = r.A;
if (instruction.IsIndexed)
{
cpu.Timing.InternalOperationCycle(5);
}
byte right = instruction.MarshalSourceByte(data, cpu, out ushort address, out ByteRegister source);
var sum = ALUOperations.Add(left, right, false);
r.A = sum.Result;
flags = sum.Flags;
}
return(new ExecutionResult(package, flags));
}