private InstructionTimings Interpret(IRegisters registers, IMmu mmu, IAlu alu, IPeripheralManager peripherals, DecodedBlock block)
{
var helper = new InterpreterHelper(registers, mmu, alu, peripherals);
var result = block.Operations.Select(o => Interpret(registers, mmu, alu, peripherals, helper, o, block)).Aggregate((t0, t1) => t0 + t1);
if (_cpuMode == CpuMode.Z80)
{
// Add the block length to the 7 lsb of memory refresh register.
registers.R = (byte)((registers.R + block.Length) & 0x7f);
}
return(result);
}
private InstructionTimings Interpret(IRegisters registers, IMmu mmu, IAlu alu, IPeripheralManager peripherals, InterpreterHelper helper, Operation operation, DecodedBlock block)
{
helper.Operation = operation;
var timer = new InstructionTimingsBuilder();
switch (operation.OpCode)
{
case OpCode.NoOperation:
break;
case OpCode.Stop:
case OpCode.Halt:
SyncProgramCounter(registers, block);
break;
case OpCode.Load:
if (operation.Operand1 == operation.Operand2)
{
break;
}
helper.Operand1 = helper.Operand2;
if (operation.Operand2 == Operand.I || operation.Operand2 == Operand.R)
{
// LD A, R & LD A, I also reset H & N and copy IFF2 to P/V
registers.AccumulatorAndFlagsRegisters.Flags.SetResultFlags(registers.AccumulatorAndFlagsRegisters.A);
registers.AccumulatorAndFlagsRegisters.Flags.HalfCarry = false;
registers.AccumulatorAndFlagsRegisters.Flags.Subtract = false;
registers.AccumulatorAndFlagsRegisters.Flags.ParityOverflow = registers.InterruptFlipFlop2;
}
break;
case OpCode.Load16:
helper.WordOperand1 = helper.WordOperand2;
break;
case OpCode.Push:
helper.PushStackPointer();
mmu.WriteWord(registers.StackPointer, helper.WordOperand1);
break;
case OpCode.Pop:
helper.WordOperand1 = mmu.ReadWord(registers.StackPointer);
helper.PopStackPointer();
break;
case OpCode.Add:
helper.Alu8BitOperation(alu.Add);
break;
case OpCode.AddWithCarry:
helper.Alu8BitOperation(alu.AddWithCarry);
break;
case OpCode.Subtract:
helper.Alu8BitOperation(alu.Subtract);
break;
case OpCode.SubtractWithCarry:
helper.Alu8BitOperation(alu.SubtractWithCarry);
break;
case OpCode.And:
helper.Alu8BitOperation(alu.And);
break;
case OpCode.Or:
helper.Alu8BitOperation(alu.Or);
break;
case OpCode.Xor:
helper.Alu8BitOperation(alu.Xor);
break;
case OpCode.Compare:
alu.Compare(registers.AccumulatorAndFlagsRegisters.A, helper.Operand1);
break;
case OpCode.Increment:
helper.Operand1 = alu.Increment(helper.Operand1);
break;
case OpCode.Decrement:
helper.Operand1 = alu.Decrement(helper.Operand1);
break;
case OpCode.Add16:
helper.Alu16BitOperation(alu.Add);
break;
case OpCode.AddWithCarry16:
helper.Alu16BitOperation(alu.AddWithCarry);
break;
case OpCode.SubtractWithCarry16:
helper.Alu16BitOperation(alu.SubtractWithCarry);
break;
case OpCode.Increment16:
// INC ss (no flags changes so implemented directly)
helper.WordOperand1 = (ushort)(helper.WordOperand1 + 1);
break;
case OpCode.Decrement16:
// DEC ss (no flags changes so implemented directly)
helper.WordOperand1 = (ushort)(helper.WordOperand1 - 1);
break;
case OpCode.Exchange:
{
var w = helper.WordOperand2;
helper.WordOperand2 = helper.WordOperand1;
helper.WordOperand1 = w;
}
break;
case OpCode.ExchangeAccumulatorAndFlags:
registers.SwitchToAlternativeAccumulatorAndFlagsRegisters();
break;
case OpCode.ExchangeGeneralPurpose:
registers.SwitchToAlternativeGeneralPurposeRegisters();
break;
case OpCode.Jump:
if (operation.FlagTest == FlagTest.None || helper.DoFlagTest())
{
registers.ProgramCounter = helper.WordOperand1;
}
else
{
SyncProgramCounter(registers, block);
}
break;
case OpCode.JumpRelative:
if (operation.FlagTest == FlagTest.None || helper.DoFlagTest())
{
helper.JumpToDisplacement();
if (operation.FlagTest != FlagTest.None)
{
timer.Add(1, 5);
}
}
SyncProgramCounter(registers, block);
break;
case OpCode.DecrementJumpRelativeIfNonZero:
registers.GeneralPurposeRegisters.B--;
if (registers.GeneralPurposeRegisters.B != 0)
{
helper.JumpToDisplacement();
timer.Add(1, 5);
}
SyncProgramCounter(registers, block);
break;
case OpCode.Call:
SyncProgramCounter(registers, block);
if (operation.FlagTest == FlagTest.None || helper.DoFlagTest())
{
helper.PushStackPointer();
mmu.WriteWord(registers.StackPointer, registers.ProgramCounter);
registers.ProgramCounter = helper.WordOperand1;
if (operation.FlagTest != FlagTest.None)
{
timer.Add(2, 7);
}
}
break;
case OpCode.Return:
if (operation.FlagTest == FlagTest.None || helper.DoFlagTest())
{
registers.ProgramCounter = mmu.ReadWord(registers.StackPointer);
helper.PopStackPointer();
if (operation.FlagTest != FlagTest.None)
{
timer.Add(2, 6);
}
}
else
{
SyncProgramCounter(registers, block);
}
break;
case OpCode.ReturnFromInterrupt:
registers.ProgramCounter = mmu.ReadWord(registers.StackPointer);
helper.PopStackPointer();
registers.InterruptFlipFlop1 = true;
break;
case OpCode.ReturnFromNonmaskableInterrupt:
registers.ProgramCounter = mmu.ReadWord(registers.StackPointer);
helper.PopStackPointer();
registers.InterruptFlipFlop1 = registers.InterruptFlipFlop2;
break;
case OpCode.Reset:
SyncProgramCounter(registers, block);
helper.PushStackPointer();
mmu.WriteWord(registers.StackPointer, registers.ProgramCounter);
registers.ProgramCounter = helper.WordOperand1;
break;
case OpCode.Input:
helper.Operand1 = peripherals.ReadByteFromPort(helper.Operand2,
operation.Operand2 == Operand.n
? registers.AccumulatorAndFlagsRegisters.A
: registers.GeneralPurposeRegisters.B);
break;
case OpCode.Output:
peripherals.WriteByteToPort(helper.Operand2,
operation.Operand2 == Operand.n
? registers.AccumulatorAndFlagsRegisters.A
: registers.GeneralPurposeRegisters.B,
helper.Operand1);
break;
case OpCode.RotateLeftWithCarry:
helper.Operand1 = alu.RotateLeftWithCarry(helper.Operand1);
if (operation.OpCodeMeta == OpCodeMeta.UseAlternativeFlagAffection)
{
registers.AccumulatorAndFlagsRegisters.Flags.Zero = false;
registers.AccumulatorAndFlagsRegisters.Flags.Sign = false;
}
break;
case OpCode.RotateLeft:
helper.Operand1 = alu.RotateLeft(helper.Operand1);
if (operation.OpCodeMeta == OpCodeMeta.UseAlternativeFlagAffection)
{
registers.AccumulatorAndFlagsRegisters.Flags.Zero = false;
registers.AccumulatorAndFlagsRegisters.Flags.Sign = false;
}
break;
case OpCode.RotateRightWithCarry:
helper.Operand1 = alu.RotateRightWithCarry(helper.Operand1);
if (operation.OpCodeMeta == OpCodeMeta.UseAlternativeFlagAffection)
{
registers.AccumulatorAndFlagsRegisters.Flags.Zero = false;
registers.AccumulatorAndFlagsRegisters.Flags.Sign = false;
}
break;
case OpCode.RotateRight:
helper.Operand1 = alu.RotateRight(helper.Operand1);
if (operation.OpCodeMeta == OpCodeMeta.UseAlternativeFlagAffection)
{
registers.AccumulatorAndFlagsRegisters.Flags.Zero = false;
registers.AccumulatorAndFlagsRegisters.Flags.Sign = false;
}
break;
case OpCode.RotateLeftDigit:
{
var result = alu.RotateLeftDigit(registers.AccumulatorAndFlagsRegisters.A,
mmu.ReadByte(registers.GeneralPurposeRegisters.HL));
registers.AccumulatorAndFlagsRegisters.A = result.Accumulator;
mmu.WriteByte(registers.GeneralPurposeRegisters.HL, result.Result);
}
break;
case OpCode.RotateRightDigit:
{
var result = alu.RotateRightDigit(registers.AccumulatorAndFlagsRegisters.A,
mmu.ReadByte(registers.GeneralPurposeRegisters.HL));
registers.AccumulatorAndFlagsRegisters.A = result.Accumulator;
mmu.WriteByte(registers.GeneralPurposeRegisters.HL, result.Result);
}
break;
case OpCode.ShiftLeft:
helper.Operand1 = alu.ShiftLeft(helper.Operand1);
break;
case OpCode.ShiftLeftSet:
helper.Operand1 = alu.ShiftLeftSet(helper.Operand1);
break;
case OpCode.ShiftRight:
helper.Operand1 = alu.ShiftRight(helper.Operand1);
break;
case OpCode.ShiftRightLogical:
helper.Operand1 = alu.ShiftRightLogical(helper.Operand1);
break;
case OpCode.BitTest:
alu.BitTest(helper.Operand1, operation.ByteLiteral);
break;
case OpCode.BitSet:
helper.Operand1 = alu.BitSet(helper.Operand1, operation.ByteLiteral);
break;
case OpCode.BitReset:
helper.Operand1 = alu.BitReset(helper.Operand1, operation.ByteLiteral);
break;
case OpCode.TransferIncrement:
helper.BlockTransfer();
break;
case OpCode.TransferIncrementRepeat:
helper.BlockTransferRepeat(timer);
break;
case OpCode.TransferDecrement:
helper.BlockTransfer(true);
break;
case OpCode.TransferDecrementRepeat:
helper.BlockTransferRepeat(timer, true);
break;
case OpCode.SearchIncrement:
helper.BlockSearch();
break;
case OpCode.SearchIncrementRepeat:
helper.BlockSearchRepeat(timer);
break;
case OpCode.SearchDecrement:
helper.BlockSearch(true);
break;
case OpCode.SearchDecrementRepeat:
helper.BlockSearchRepeat(timer, true);
break;
case OpCode.InputTransferIncrement:
helper.InputTransfer();
break;
case OpCode.InputTransferIncrementRepeat:
helper.InputTransferRepeat(timer);
break;
case OpCode.InputTransferDecrement:
helper.InputTransfer(true);
break;
case OpCode.InputTransferDecrementRepeat:
helper.InputTransferRepeat(timer, true);
break;
case OpCode.OutputTransferIncrement:
helper.OutputTransfer();
break;
case OpCode.OutputTransferIncrementRepeat:
helper.OutputTransferRepeat(timer);
break;
case OpCode.OutputTransferDecrement:
helper.OutputTransfer(true);
break;
case OpCode.OutputTransferDecrementRepeat:
helper.OutputTransferRepeat(timer, true);
break;
case OpCode.DecimalArithmeticAdjust:
registers.AccumulatorAndFlagsRegisters.A = alu.DecimalAdjust(registers.AccumulatorAndFlagsRegisters.A,
_cpuMode == CpuMode.Z80);
break;
case OpCode.NegateOnesComplement:
registers.AccumulatorAndFlagsRegisters.A = (byte)~registers.AccumulatorAndFlagsRegisters.A;
registers.AccumulatorAndFlagsRegisters.Flags.SetUndocumentedFlags(registers.AccumulatorAndFlagsRegisters.A);
registers.AccumulatorAndFlagsRegisters.Flags.HalfCarry = true;
registers.AccumulatorAndFlagsRegisters.Flags.Subtract = true;
break;
case OpCode.NegateTwosComplement:
registers.AccumulatorAndFlagsRegisters.A = alu.Subtract(0, registers.AccumulatorAndFlagsRegisters.A);
break;
case OpCode.InvertCarryFlag:
registers.AccumulatorAndFlagsRegisters.Flags.SetUndocumentedFlags(registers.AccumulatorAndFlagsRegisters.A);
registers.AccumulatorAndFlagsRegisters.Flags.HalfCarry = _cpuMode != CpuMode.GameBoy &&
registers.AccumulatorAndFlagsRegisters.Flags.Carry;
registers.AccumulatorAndFlagsRegisters.Flags.Subtract = false;
registers.AccumulatorAndFlagsRegisters.Flags.Carry = !registers.AccumulatorAndFlagsRegisters.Flags.Carry;
break;
case OpCode.SetCarryFlag:
registers.AccumulatorAndFlagsRegisters.Flags.SetUndocumentedFlags(registers.AccumulatorAndFlagsRegisters.A);
registers.AccumulatorAndFlagsRegisters.Flags.HalfCarry = false;
registers.AccumulatorAndFlagsRegisters.Flags.Subtract = false;
registers.AccumulatorAndFlagsRegisters.Flags.Carry = true;
break;
case OpCode.DisableInterrupts:
registers.InterruptFlipFlop1 = false;
registers.InterruptFlipFlop2 = false;
break;
case OpCode.EnableInterrupts:
registers.InterruptFlipFlop1 = true;
registers.InterruptFlipFlop2 = true;
break;
case OpCode.InterruptMode0:
registers.InterruptMode = InterruptMode.InterruptMode0;
break;
case OpCode.InterruptMode1:
registers.InterruptMode = InterruptMode.InterruptMode1;
break;
case OpCode.InterruptMode2:
registers.InterruptMode = InterruptMode.InterruptMode2;
break;
case OpCode.Swap:
helper.Operand1 = alu.Swap(helper.Operand1);
break;
case OpCode.LoadIncrement:
helper.Operand1 = helper.Operand2;
registers.GeneralPurposeRegisters.HL++;
break;
case OpCode.LoadDecrement:
helper.Operand1 = helper.Operand2;
registers.GeneralPurposeRegisters.HL--;
break;
default:
throw new ArgumentOutOfRangeException();
}
if (operation.OpCodeMeta == OpCodeMeta.AutoCopy)
{
// Autocopy for DD/FD prefix
helper.Operand2 = helper.Operand1;
}
return(timer.GetInstructionTimings());
}