public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 5:
_writeAddress = mainMemory.ReadByte(cpuState.ProgramCounter++);
break;
case 4:
_writeAddress |= (ushort)(mainMemory.ReadByte(cpuState.ProgramCounter++) << 8);
break;
case 3:
//write lsb of stack pointer
mainMemory.WriteByte(_writeAddress, (byte)cpuState.StackPointer);
break;
case 2:
//write msb of stack pointer
mainMemory.WriteByte((ushort)(_writeAddress + 1), (byte)(cpuState.StackPointer >> 8));
break;
case 1:
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}
public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 6:
//read jump address lsb
_jumpAddress = mainMemory.ReadByte(cpuState.ProgramCounter++);
break;
case 5:
//read jump address msb
_jumpAddress |= (ushort)(mainMemory.ReadByte(cpuState.ProgramCounter++) << 8);
break;
case 3:
//write msb of program counter to stack
mainMemory.WriteByte(--cpuState.StackPointer, (byte)(cpuState.ProgramCounter >> 8));
break;
case 2:
//write lsb of program counter to stack
mainMemory.WriteByte(--cpuState.StackPointer, (byte)(cpuState.ProgramCounter & 0x00FF));
break;
case 1:
//do the jump
cpuState.ProgramCounter = _jumpAddress;
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}
public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 4:
//calculate jump address
_jumpAddress = (ushort)(_opcode & 0x38);
break;
case 3:
//write msb of program counter to stack
mainMemory.WriteByte(--cpuState.StackPointer, (byte)(cpuState.ProgramCounter >> 8));
break;
case 2:
//write lsb of program counter to stack
mainMemory.WriteByte(--cpuState.StackPointer, (byte)(cpuState.ProgramCounter & 0x00FF));
break;
case 1:
//do the jump
cpuState.ProgramCounter = _jumpAddress;
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}
internal void RequestVBlankInterrupt()
{
var currentIf = _mainMemory.ReadByte(MiscRegisters.InterruptFlags);
_mainMemory.WriteByte(MiscRegisters.InterruptFlags, (byte)(currentIf | 0x01));
NotifyNextFrameReady();
SwapBuffers();
}
public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 3:
_currentData = mainMemory.ReadByte(cpuState.Registers.HL);
break;
case 2:
_hiBit = _currentData & 0x80;
_loBit = _currentData & 0x01;
_writeData = (byte)(_currentData >> 1);
_writeData |= (byte)_hiBit;
mainMemory.WriteByte(cpuState.Registers.HL, _writeData);
cpuState.Registers.CarryFlag = _loBit == 0x01;
cpuState.Registers.ZeroFlag = _writeData == 0;
cpuState.Registers.HalfCarryFlag = false;
cpuState.Registers.SubtractionFlag = false;
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}
public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 3:
_currentData = mainMemory.ReadByte(cpuState.Registers.HL);
break;
case 2:
byte lowNibble = (byte)(_currentData & 0x0F);
byte highNibble = (byte)(_currentData & 0xF0);
_writeData = (byte)((lowNibble << 4) | (highNibble >> 4));
mainMemory.WriteByte(cpuState.Registers.HL, _writeData);
cpuState.Registers.ZeroFlag = _writeData == 0;
cpuState.Registers.HalfCarryFlag = false;
cpuState.Registers.SubtractionFlag = false;
cpuState.Registers.CarryFlag = false;
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}
public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 2:
mainMemory.WriteByte(cpuState.Registers.BC, cpuState.Registers.A);
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}
public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 4:
_registerBits = (byte)((_opcode >> 4) & 0x03);
LoadWriteData(cpuState);
break;
case 3:
mainMemory.WriteByte(--cpuState.StackPointer, _msbData);
break;
case 2:
mainMemory.WriteByte(--cpuState.StackPointer, _lsbData);
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}
public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 2:
var registerIndex = _opcode & 0x07;
mainMemory.WriteByte(cpuState.Registers.HL, (byte)cpuState.Registers[registerIndex]);
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}
public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 3:
_loadData = mainMemory.ReadByte(cpuState.ProgramCounter++);
break;
case 2:
mainMemory.WriteByte(cpuState.Registers.HL, _loadData);
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}
public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 3:
_addressLsb = mainMemory.ReadByte(cpuState.ProgramCounter++);
break;
case 2:
mainMemory.WriteByte((ushort)((0xFF << 8) | _addressLsb), cpuState.Registers.A);
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}
public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 3:
_currentData = mainMemory.ReadByte(cpuState.Registers.HL);
var bitIndex = (_opcode & 0x38) >> 3;
_writeData = (byte)(_currentData & ~(0x01 << bitIndex));
break;
case 2:
mainMemory.WriteByte(cpuState.Registers.HL, _writeData);
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}
public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 3:
_currentData = mainMemory.ReadByte(cpuState.Registers.HL);
break;
case 2:
_decrementedData = (byte)(_currentData - 1);
mainMemory.WriteByte(cpuState.Registers.HL, _decrementedData);
break;
case 1:
cpuState.Registers.ZeroFlag = _decrementedData == 0;
cpuState.Registers.SubtractionFlag = true;
cpuState.Registers.HalfCarryFlag = (_currentData & 0x0F) == 0;
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}
public override void ExecuteCycle(ICpuState cpuState, IRandomAccessMemory mainMemory)
{
switch (_remainingCycles)
{
case 3:
mainMemory.WriteByte(--cpuState.StackPointer, (byte)(cpuState.ProgramCounter >> 8));
break;
case 2:
mainMemory.WriteByte(--cpuState.StackPointer, (byte)(cpuState.ProgramCounter & 0x00FF));
break;
case 1:
var interruptFlags = mainMemory.ReadByte(MiscRegisters.InterruptFlags);
//vblank interrupt
if ((_readyInterrupts & 0x01) == 0x01)
{
//Console.WriteLine("Loading vblank isr...");
cpuState.ProgramCounter = InterruptAddresses.VblankInterrupt;
mainMemory.WriteByte(MiscRegisters.InterruptFlags, (byte)(interruptFlags & 0xFE));
}
//lcd stat interrupt
else if ((_readyInterrupts & 0x02) == 0x02)
{
//Console.WriteLine("Loading lcd stat isr...");
cpuState.ProgramCounter = InterruptAddresses.LcdInterrupt;
//clear interrupt flag
mainMemory.WriteByte(MiscRegisters.InterruptFlags, (byte)(interruptFlags & 0xFD));
}
//timer interrupt
else if ((_readyInterrupts & 0x04) == 0x04)
{
//Console.WriteLine("Loading timer isr...");
cpuState.ProgramCounter = InterruptAddresses.TimerInterrupt;
//clear interrupt flag
mainMemory.WriteByte(MiscRegisters.InterruptFlags, (byte)(interruptFlags & 0xFB));
}
//serial interrupt
else if ((_readyInterrupts & 0x08) == 0x08)
{
cpuState.ProgramCounter = InterruptAddresses.SerialInterrupt;
//clear interrupt flag
mainMemory.WriteByte(MiscRegisters.InterruptFlags, (byte)(interruptFlags & 0xF7));
}
//joypad interrupt
else if ((_readyInterrupts & 0x10) == 0x10)
{
cpuState.ProgramCounter = InterruptAddresses.JoypadInterrupt;
//clear interrupt flag
mainMemory.WriteByte(MiscRegisters.InterruptFlags, (byte)(interruptFlags & 0x0F));
}
cpuState.InterruptMasterEnable = false;
break;
}
base.ExecuteCycle(cpuState, mainMemory);
}