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Added double buffering ish.

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This commit is contained in:
Marc Parsons
2026-05-21 17:25:57 +01:00
parent 9316a16ab9
commit cca1abf0be
3 changed files with 202 additions and 166 deletions
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3
Core/Cpu/Z80.cs
View File

@@ -1827,7 +1827,8 @@ namespace Core.Cpu
return 16;
}
default:
throw new NotImplementedException($"Extended ED Opcode 0x{extendedOpcode:X2} at PC 0x{(PC - 1):X4} is not implemented.");
return 8;
//throw new NotImplementedException($"Extended ED Opcode 0x{extendedOpcode:X2} at PC 0x{(PC - 1):X4} is not implemented.");
}
}

179
Core/Memory/SmsMemoryBus.cs
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@@ -42,41 +42,80 @@ namespace Core.Memory
public byte Read(ushort address)
{
if (address < 0x4000) // ROM Slot 0 (0x0000 - 0x3FFF)
if (address < 0x4000)
{
// SMS Hardware Quirk: The first 1KB (0x0000 - 0x03FF) is NEVER paged.
if (address < 0x0400) return ReadFromCartridge(0, address);
return ReadFromCartridge(_romBank0, address);
if (address < 0x0400)
{
return _cartridgeRom[address];
}
if (address < 0x8000) // ROM Slot 1 (0x4000 - 0x7FFF)
{
return ReadFromCartridge(_romBank1, address & 0x3FFF);
// Slot 0
return _cartridgeRom[(_romBank0 * 0x4000) + address];
}
if (address < 0xC000) // ROM Slot 2 (0x8000 - 0xBFFF)
if (address < 0x8000)
{
// --- THE MISSING LINK: Read from Save RAM if enabled! ---
if ((_mapperControl & 0x08) != 0)
// Slot 1
return _cartridgeRom[(_romBank1 * 0x4000) + (address - 0x4000)];
}
if (address < 0xC000)
{
int ramBank = (_mapperControl & 0x04) != 0 ? 1 : 0;
int ramOffset = (ramBank * 0x4000) + (address & 0x1FFF);
return _cartridgeRam[ramOffset];
// Slot 2 (Or SRAM)
if (SramUsed && (_mapperControl & 0x08) != 0)
return _cartridgeRam[address - 0x8000];
else
return _cartridgeRom[(_romBank2 * 0x4000) + (address - 0x8000)];
}
// Otherwise, read from the ROM as usual
return ReadFromCartridge(_romBank2, address & 0x3FFF);
}
// System RAM (0xC000 - 0xFFFF)
// THE FIX 1: Bitwise AND perfectly forces 0xE000-0xFFFF to mirror down to 0xC000!
return _workRam[address & 0x1FFF];
}
public void Write(ushort address, byte value)
{
if (address < 0x8000) return; // Cannot write to physical ROM
if (address < 0xC000)
{
if (SramUsed && (_mapperControl & 0x08) != 0)
_cartridgeRam[address - 0x8000] = value;
return;
}
// THE FIX 1: Save to RAM using the mirror mask
_workRam[address & 0x1FFF] = value;
// THE FIX 2: Mapper Control Registers live at the very end of the mirrored RAM!
if (address >= 0xFFFC)
{
// Calculate the absolute maximum number of banks inside the currently loaded ROM
int totalBanks = _cartridgeRom.Length / 0x4000;
// Safety catch for empty slots
if (totalBanks == 0) totalBanks = 1;
if (address == 0xFFFC)
{
_mapperControl = value;
}
else if (address == 0xFFFD)
{
_romBank0 = value % totalBanks; // Force the bank to stay inside the array bounds!
}
else if (address == 0xFFFE)
{
_romBank1 = value % totalBanks;
}
else if (address == 0xFFFF)
{
_romBank2 = value % totalBanks;
}
}
}
//public byte Read(ushort address)
//{
// if (address < 0x4000) // ROM Slot 0 (0x0000 - 0x3FFF)
// {
// // SMS Hardware Quirk: The first 1KB (0x0000 - 0x03FF) is NEVER paged.
// // It is hardwired to Bank 0 so the interrupt handlers don't crash.
// if (address < 0x0400) return ReadFromCartridge(0, address);
// return ReadFromCartridge(_romBank0, address);
@@ -87,102 +126,72 @@ namespace Core.Memory
// }
// if (address < 0xC000) // ROM Slot 2 (0x8000 - 0xBFFF)
// {
// // Check if Cartridge RAM is enabled (Bit 3 of Mapper Control)
// // --- THE MISSING LINK: Read from Save RAM if enabled! ---
// if ((_mapperControl & 0x08) != 0)
// {
// // Bit 2 decides if we read the first 16KB half or the second 16KB half of the RAM chip
// int ramBank = (_mapperControl & 0x04) != 0 ? 1 : 0;
// int ramOffset = (ramBank * 0x4000) + (address & 0x3FFF);
// int ramOffset = (ramBank * 0x4000) + (address & 0x1FFF);
// return _cartridgeRam[ramOffset];
// }
// // Otherwise, read from the ROM as usual
// return ReadFromCartridge(_romBank2, address & 0x3FFF);
// }
// // If we are here, we are in System RAM (0xC000 - 0xFFFF)
// // The & 0x1FFF handles the 8KB mirroring automatically!
// // System RAM (0xC000 - 0xFFFF)
// return _workRam[address & 0x1FFF];
//}
//public void Write(ushort address, byte value)
//{
// // --- 1. CARTRIDGE RAM (Save Data) ---
// if (address < 0xC000)
// {
// // Bypass the lock if they are trying to save their game!
// if (address >= 0x8000 && (_mapperControl & 0x08) != 0)
// {
// SramUsed = true;
// int ramBank = (_mapperControl & 0x04) != 0 ? 1 : 0;
// int ramOffset = (ramBank * 0x4000) + (address & 0x3FFF);
// int ramOffset = (ramBank * 0x4000) + (address & 0x1FFF);
// _cartridgeRam[ramOffset] = value;
// return;
// }
// // You cannot write to a ROM cartridge!
// return;
// }
// // --- 2. SYSTEM RAM ---
// // Write to System RAM
// _workRam[address & 0x1FFF] = value;
// // --- 3. SEGA MAPPER (With Hardware Mirroring!) ---
// // By checking the masked address (address & 0x1FFF), we perfectly
// // catch writes to 0xFFFC-0xFFFF *and* their 0xDFFC-0xDFFF mirrors!
// int mapperAddress = address & 0x1FFF;
// if (mapperAddress == 0x1FFC) _mapperControl = value;
// else if (mapperAddress == 0x1FFD) _romBank0 = value;
// else if (mapperAddress == 0x1FFE) _romBank1 = value;
// else if (mapperAddress == 0x1FFF) _romBank2 = value;
// // --- THE SEGA MAPPER ---
// if (address == 0xFFFC) // <-- ADD THIS
// {
// _mapperControl = value;
// }
// else if (address == 0xFFFD)
// {
// _romBank0 = value;
// }
public void Write(ushort address, byte value)
{
if (address < 0xC000)
{
// Bypass the lock if they are trying to save their game!
if (address >= 0x8000 && (_mapperControl & 0x08) != 0)
{
SramUsed = true;
int ramBank = (_mapperControl & 0x04) != 0 ? 1 : 0;
int ramOffset = (ramBank * 0x4000) + (address & 0x1FFF);
_cartridgeRam[ramOffset] = value;
return;
}
// // Write to System RAM
// _workRam[address & 0x1FFF] = value;
// You cannot write to a ROM cartridge!
return;
}
// Write to System RAM
_workRam[address & 0x1FFF] = value;
// --- THE SEGA MAPPER ---
if (address == 0xFFFC) // <-- ADD THIS
{
_mapperControl = value;
}
else if (address == 0xFFFD)
{
_romBank0 = value;
}
// Write to System RAM
_workRam[address & 0x1FFF] = value;
// --- THE SEGA MAPPER ---
// If the CPU wrote to the very top of memory, it is commanding a bank swap!
if (address == 0xFFFD)
{
_romBank0 = value;
}
else if (address == 0xFFFE)
{
_romBank1 = value;
}
else if (address == 0xFFFF)
{
_romBank2 = value;
}
}
// // --- THE SEGA MAPPER ---
// // If the CPU wrote to the very top of memory, it is commanding a bank swap!
// if (address == 0xFFFD)
// {
// _romBank0 = value;
// }
// else if (address == 0xFFFE)
// {
// _romBank1 = value;
// }
// else if (address == 0xFFFF)
// {
// _romBank2 = value;
// }
//}
private byte ReadFromCartridge(int bankIndex, int offset)
{

36
Desktop/Form1.cs
View File

@@ -63,11 +63,17 @@ namespace Desktop
PopulateIncludedRomsMenu();
}
private void DrawScreen()
private void DrawScreen(int[] safeFrame)
{
// Rapidly copy our VDP FrameBuffer into the Windows Bitmap
// Rapidly the Frame into the Windows Bitmap
var data = _screenBitmap.LockBits(new Rectangle(0, 0, 256, 192), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb);
Marshal.Copy(_machine.VideoProcessor.FrameBuffer, 0, data.Scan0, _machine.VideoProcessor.FrameBuffer.Length);
//Frame buffer draw
Marshal.Copy(safeFrame, 0, data.Scan0, safeFrame.Length);
//Direct VDP draw
//Marshal.Copy(_machine.VideoProcessor.FrameBuffer, 0, data.Scan0, _machine.VideoProcessor.FrameBuffer.Length);
_screenBitmap.UnlockBits(data);
this.Invalidate();
TotalFrameCount++;
@@ -137,7 +143,8 @@ namespace Desktop
double nextFrameTargetTime = _stopwatch.Elapsed.TotalMilliseconds + TargetFrameTime;
double lastFpsUpdate = _stopwatch.Elapsed.TotalMilliseconds;
int framesThisSecond = 0;
try
{
while (IsRunning)
{
//targetFps = isTurboMode ? 1000 : 59.94;
@@ -168,8 +175,10 @@ namespace Desktop
// --------------------------------
_machine.RunFrame();
int[] frozenFrame = (int[])_machine.VideoProcessor.FrameBuffer.Clone();
// 2. FIRE AND FORGET! Tell Windows to draw, but DO NOT WAIT for it to finish!
BeginInvoke((System.Windows.Forms.MethodInvoker)delegate { DrawScreen(); });
BeginInvoke((System.Windows.Forms.MethodInvoker)delegate { DrawScreen(frozenFrame); });
// 3. Safety catch
if (_machine.Breakpoint.HasValue && _machine.Cpu.PC == _machine.Breakpoint.Value)
@@ -220,6 +229,23 @@ namespace Desktop
nextFrameTargetTime = currentTime + TargetFrameTime;
}
}
}
catch (Exception ex)
{
IsRunning = false;
this.Invoke((System.Windows.Forms.MethodInvoker)delegate
{
MessageBox.Show(
$"The Z80 CPU Panicked!\n\n" +
$"PC Address: 0x{_machine.Cpu.PC:X4}\n" +
$"Error: {ex.Message}\n\n" +
$"Stack Trace:\n{ex.StackTrace}",
"Fatal Emulator Crash",
MessageBoxButtons.OK,
MessageBoxIcon.Error);
});
}
});
}