public override void ComputeNextFrame(FrameBuffer frameBuffer)
{
base.ComputeNextFrame(frameBuffer);
AssertDebug(CPU.Jammed || CPU.RunClocks <= 0 && (CPU.RunClocks % CPU.RunClocksMultiple) == 0);
AssertDebug(CPU.Jammed || ((CPU.Clock + (ulong)(CPU.RunClocks / CPU.RunClocksMultiple)) % (114 * (ulong)FrameBuffer.Scanlines)) == 0);
ulong startOfScanlineCpuClock = 0;
Maria.StartFrame();
Cart.StartFrame();
for (var i = 0; i < FrameBuffer.Scanlines && !CPU.Jammed; i++)
{
AssertDebug(CPU.RunClocks <= 0 && (CPU.RunClocks % CPU.RunClocksMultiple) == 0);
var newStartOfScanlineCpuClock = CPU.Clock + (ulong)(CPU.RunClocks / CPU.RunClocksMultiple);
AssertDebug(startOfScanlineCpuClock == 0 || newStartOfScanlineCpuClock == startOfScanlineCpuClock + 114);
startOfScanlineCpuClock = newStartOfScanlineCpuClock;
CPU.RunClocks += (7 * CPU.RunClocksMultiple);
var remainingRunClocks = (114 - 7) * CPU.RunClocksMultiple;
CPU.Execute();
if (CPU.Jammed)
{
break;
}
if (CPU.EmulatorPreemptRequest)
{
Maria.DoDMAProcessing();
var remainingCpuClocks = 114 - (CPU.Clock - startOfScanlineCpuClock);
CPU.Clock += remainingCpuClocks;
CPU.RunClocks = 0;
continue;
}
var dmaClocks = Maria.DoDMAProcessing();
// CHEAT: Ace of Aces: Title screen has a single scanline flicker without this. Maria DMA clock counting probably not 100% accurate.
if (i == 203 && FrameBuffer.Scanlines == 262 /*NTSC*/ || i == 228 && FrameBuffer.Scanlines == 312 /*PAL*/)
{
if (dmaClocks == 152 && remainingRunClocks == 428 && (CPU.RunClocks == -4 || CPU.RunClocks == -8))
{
dmaClocks -= 4;
}
}
// Unsure exactly what to do if Maria DMA processing extends past the current scanline.
// For now, throw away half remaining until we are within the current scanline.
// KLAX initialization starts DMA without initializing the DLL data structure.
// Maria processing then runs away causing an invalid CPU opcode to be executed that jams the machine.
// So Maria must give up at some point, but not clear exactly how.
// Anyway, this makes KLAX work without causing breakage elsewhere.
while ((CPU.RunClocks + remainingRunClocks) < dmaClocks)
{
dmaClocks >>= 1;
}
// Assume the CPU waits until the next div4 boundary to proceed after DMA processing.
if ((dmaClocks & 3) != 0)
{
dmaClocks += 4;
dmaClocks -= (dmaClocks & 3);
}
CPU.Clock += (ulong)(dmaClocks / CPU.RunClocksMultiple);
CPU.RunClocks -= dmaClocks;
CPU.RunClocks += remainingRunClocks;
CPU.Execute();
if (CPU.Jammed)
{
break;
}
if (CPU.EmulatorPreemptRequest)
{
var remainingCpuClocks = 114 - (CPU.Clock - startOfScanlineCpuClock);
CPU.Clock += remainingCpuClocks;
CPU.RunClocks = 0;
}
}
Cart.EndFrame();
Maria.EndFrame();
}
