public void Update(int cpuCycles)
{
byte controlRegister = memory.ReadByte(0xFF40);
if (controlRegister.IsBitSet(7) == false)
{
// Disabling LCD can be only done during VBlank
CurrentMode = Mode.VBlank;
cycles = 456;
CurrentLine = 0;
windowLine = 0;
return;
}
cycles += cpuCycles;
switch (CurrentMode)
{
case Mode.OamSearch:
if (cycles >= 80)
{
CurrentMode = Mode.PixelTransfer;
cycles -= 80;
}
break;
case Mode.PixelTransfer:
if (cycles >= 172)
{
CurrentMode = Mode.HBlank;
cycles -= 172;
RenderScanLine(controlRegister);
}
break;
case Mode.HBlank:
if (cycles >= 204)
{
CurrentLine++;
cycles -= 204;
if (CurrentLine == HEIGHT)
{
CurrentMode = Mode.VBlank;
CPU.RequestInterrupt(memory, CPU.Interrupt.VBlank);
RenderEvent?.Invoke();
}
else
{
CurrentMode = Mode.OamSearch;
}
}
break;
case Mode.VBlank:
if (cycles >= 456)
{
cycles -= 456;
// Not really rendering anything but the line counter keeps updating during the V-Blank period
if (CurrentLine == 153)
{
CurrentMode = Mode.OamSearch;
CurrentLine = 0;
windowLine = 0;
}
else
{
CurrentLine++;
}
}
break;
}
}