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Implemenmted rendering priorities

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This commit is contained in:
Marc Parsons
2026-05-12 00:30:28 +01:00
parent f825e102a2
commit 95ac0ec7c1
5 changed files with 125 additions and 55 deletions
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58
Core/Video/SmsVdp.cs
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@@ -9,6 +9,7 @@ namespace Core.Video
public byte[] CRAM { get; private set; } = new byte[0x20]; // 32 Bytes Color Palette
public byte[] Registers { get; private set; } = new byte[16]; // 11 Hardware Control Registers
public int[] FrameBuffer { get; private set; } = new int[256 * 192];
private bool[] _priorityBuffer = new bool[256 * 192]; // Tracks priority pixels!
// The Control Port State Machine (Port 0xBF)
private bool _isSecondControlByte = false;
@@ -131,18 +132,19 @@ namespace Core.Video
private void RenderBackground()
{
ushort nameTableBase = (ushort)((Registers[2] & 0x0E) << 10);
byte scrollX = Registers[8];
byte scrollY = Registers[9];
bool lockRowScroll = (Registers[0] & 0x80) != 0; // Top 2 rows (Y < 16)
bool lockColScroll = (Registers[0] & 0x40) != 0; // Right 8 columns (X >= 192)
bool lockRowScroll = (Registers[0] & 0x80) != 0;
bool lockColScroll = (Registers[0] & 0x40) != 0;
// Clear the priority mask for the new frame!
Array.Clear(_priorityBuffer, 0, _priorityBuffer.Length);
for (int screenY = 0; screenY < 192; screenY++)
{
for (int screenX = 0; screenX < 256; screenX++)
{
// Apply Vertical Scrolling (Depends on X for column locking!)
int effectiveScrollY = scrollY;
if (lockColScroll && screenX >= 192) effectiveScrollY = 0;
@@ -150,7 +152,6 @@ namespace Core.Video
int row = vdpY / 8;
int tileY = vdpY % 8;
// Apply Horizontal Scrolling (Depends on Y for row locking!)
int effectiveScrollX = scrollX;
if (lockRowScroll && screenY < 16) effectiveScrollX = 0;
@@ -158,31 +159,34 @@ namespace Core.Video
int col = vdpX / 8;
int tileX = vdpX % 8;
// 1. Read the 16-bit Tile instruction from the Name Table
// 1. Read the 16-bit Tile instruction
ushort nameTableAddr = (ushort)(nameTableBase + (row * 64) + (col * 2));
byte lowByte = VRAM[nameTableAddr];
byte highByte = VRAM[nameTableAddr + 1];
ushort tileData = (ushort)((highByte << 8) | lowByte);
// 2. Extract Tile Index and Palette Info
// 2. EXTRACT ALL THE HARDWARE BITS!
int tileIndex = tileData & 0x01FF;
bool useSpritePalette = (tileData & 0x0800) != 0;
bool flipH = (tileData & 0x0200) != 0; // Bit 9
bool flipV = (tileData & 0x0400) != 0; // Bit 10
bool useSpritePalette = (tileData & 0x0800) != 0; // Bit 11
bool priority = (tileData & 0x1000) != 0; // Bit 12
// 3. Find the tile data in VRAM
// 3. Apply Vertical Flip (Read from the bottom of the tile instead of the top)
int readY = flipV ? (7 - tileY) : tileY;
ushort tileAddress = (ushort)(tileIndex * 32);
// 4. Fetch the 4 bitplanes
byte bp0 = VRAM[tileAddress + (tileY * 4) + 0];
byte bp1 = VRAM[tileAddress + (tileY * 4) + 1];
byte bp2 = VRAM[tileAddress + (tileY * 4) + 2];
byte bp3 = VRAM[tileAddress + (tileY * 4) + 3];
byte bp0 = VRAM[tileAddress + (readY * 4) + 0];
byte bp1 = VRAM[tileAddress + (readY * 4) + 1];
byte bp2 = VRAM[tileAddress + (readY * 4) + 2];
byte bp3 = VRAM[tileAddress + (readY * 4) + 3];
// 5. Extract color index
int shift = 7 - tileX;
int colorIndex = ((bp0 >> shift) & 1) |
(((bp1 >> shift) & 1) << 1) |
(((bp2 >> shift) & 1) << 2) |
(((bp3 >> shift) & 1) << 3);
// 4. Apply Horizontal Flip (Shift from right-to-left instead of left-to-right)
int readX = flipH ? tileX : (7 - tileX);
int colorIndex = ((bp0 >> readX) & 1) |
(((bp1 >> readX) & 1) << 1) |
(((bp2 >> readX) & 1) << 2) |
(((bp3 >> readX) & 1) << 3);
int paletteOffset = useSpritePalette ? 16 : 0;
byte smsColor = CRAM[paletteOffset + colorIndex];
@@ -191,7 +195,16 @@ namespace Core.Video
int g = ((smsColor >> 2) & 0x03) * 85;
int b = ((smsColor >> 4) & 0x03) * 85;
FrameBuffer[(screenY * 256) + screenX] = (255 << 24) | (r << 16) | (g << 8) | b;
int screenAddress = (screenY * 256) + screenX;
FrameBuffer[screenAddress] = (255 << 24) | (r << 16) | (g << 8) | b;
// 5. FLAG THE PRIORITY PIXEL!
// If this tile has priority AND the pixel isn't transparent (color 0),
// tell the sprite renderer not to draw over it!
if (priority && colorIndex != 0)
{
_priorityBuffer[screenAddress] = true;
}
}
}
}
@@ -262,6 +275,9 @@ namespace Core.Video
// If the color index is 0, DO NOT draw it! Let the background show through.
if (colorIndex == 0) continue;
// If the background tile at this exact pixel claimed priority, hide the sprite!
if (_priorityBuffer[(screenY * 256) + screenX]) continue;
// Sprites ALWAYS use the second half of CRAM (Palette 1: Indices 16-31)
byte smsColor = CRAM[16 + colorIndex];

10
Desktop/DebuggerForm.cs
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@@ -10,9 +10,9 @@ namespace Desktop
{
private readonly Z80 _cpu;
private readonly SmsMemoryBus _memoryBus;
private readonly Form1 _mainForm;
private readonly ParsonsForm1 _mainForm;
public DebuggerForm(Z80 cpu, SmsMemoryBus memoryBus, Form1 mainForm)
public DebuggerForm(Z80 cpu, SmsMemoryBus memoryBus, ParsonsForm1 mainForm)
{
InitializeComponent();
_cpu = cpu;
@@ -103,9 +103,9 @@ namespace Desktop
lblIE.Text = $"Interrupt Mode: {_cpu.InterruptMode}";
lblFlags.Text = $"Flags: {_cpu.GetFlagsString()}";
lblTStates.Text = $"T-States: {_cpu.TotalTStates}";
//lblFrames.Text = $"Frames Rendered: {_mainForm.TotalFrameCount}";
//lblFrameTime.Text = $"Frame Time: {((float)_mainForm.FrameTime):F1}ms";
//lblFPS.Text = $"FPS: {_mainForm.FramesPerSecond:F2}";
lblFrames.Text = $"Frames Rendered: {_mainForm.TotalFrameCount}";
lblFrameTime.Text = $"Frame Time: {((float)_mainForm.FrameTime):F1}ms";
lblFPS.Text = $"FPS: {_mainForm.FramesPerSecond:F2}";
UpdateMemoryView();
UpdateStackView();
UpdateDisassemblyView();

20
Desktop/Form1.Designer.cs generated
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@@ -1,6 +1,6 @@
namespace Desktop
{
partial class Form1
partial class ParsonsForm1
{
/// <summary>
/// Required designer variable.
@@ -49,7 +49,7 @@
//
pbScreen.Location = new Point(12, 36);
pbScreen.Name = "pbScreen";
pbScreen.Size = new Size(762, 672);
pbScreen.Size = new Size(768, 576);
pbScreen.SizeMode = PictureBoxSizeMode.Zoom;
pbScreen.TabIndex = 1;
pbScreen.TabStop = false;
@@ -60,7 +60,7 @@
menuStrip1.Items.AddRange(new ToolStripItem[] { fileToolStripMenuItem, viewToolStripMenuItem, machineToolStripMenuItem, helpToolStripMenuItem });
menuStrip1.Location = new Point(0, 0);
menuStrip1.Name = "menuStrip1";
menuStrip1.Size = new Size(785, 33);
menuStrip1.Size = new Size(791, 33);
menuStrip1.TabIndex = 2;
menuStrip1.Text = "menuStrip1";
//
@@ -75,27 +75,27 @@
//
openToolStripMenuItem.DropDownItems.AddRange(new ToolStripItem[] { includedToolStripMenuItem, selectROMToolStripMenuItem1 });
openToolStripMenuItem.Name = "openToolStripMenuItem";
openToolStripMenuItem.Size = new Size(270, 34);
openToolStripMenuItem.Size = new Size(158, 34);
openToolStripMenuItem.Text = "Open";
//
// includedToolStripMenuItem
//
includedToolStripMenuItem.Name = "includedToolStripMenuItem";
includedToolStripMenuItem.Size = new Size(270, 34);
includedToolStripMenuItem.Size = new Size(218, 34);
includedToolStripMenuItem.Text = "Included";
includedToolStripMenuItem.Click += includedToolStripMenuItem_Click;
//
// selectROMToolStripMenuItem1
//
selectROMToolStripMenuItem1.Name = "selectROMToolStripMenuItem1";
selectROMToolStripMenuItem1.Size = new Size(270, 34);
selectROMToolStripMenuItem1.Size = new Size(218, 34);
selectROMToolStripMenuItem1.Text = "Select ROM...";
selectROMToolStripMenuItem1.Click += selectROMToolStripMenuItem_Click;
//
// exitToolStripMenuItem
//
exitToolStripMenuItem.Name = "exitToolStripMenuItem";
exitToolStripMenuItem.Size = new Size(270, 34);
exitToolStripMenuItem.Size = new Size(158, 34);
exitToolStripMenuItem.Text = "Exit";
exitToolStripMenuItem.Click += exitToolStripMenuItem_Click;
//
@@ -140,16 +140,16 @@
aboutToolStripMenuItem.Size = new Size(164, 34);
aboutToolStripMenuItem.Text = "About";
//
// Form1
// ParsonsForm1
//
AutoScaleDimensions = new SizeF(10F, 25F);
AutoScaleMode = AutoScaleMode.Font;
ClientSize = new Size(785, 719);
ClientSize = new Size(791, 622);
Controls.Add(pbScreen);
Controls.Add(menuStrip1);
MainMenuStrip = menuStrip1;
Margin = new Padding(4);
Name = "Form1";
Name = "ParsonsForm1";
Text = "Form1";
((System.ComponentModel.ISupportInitialize)pbScreen).EndInit();
menuStrip1.ResumeLayout(false);

86
Desktop/Form1.cs
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@@ -1,22 +1,26 @@
using System.Diagnostics;
using System.Drawing.Imaging;
using System.Reflection;
using System.Reflection.PortableExecutable;
using Core;
using System.Threading.Tasks;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.Threading.Tasks;
using System.Windows.Forms;
using Core;
namespace Desktop
{
public partial class Form1 : Form
public partial class ParsonsForm1 : Form
{
private SmsMachine _machine = null!;
private DebuggerForm _debugger;
private Bitmap _screenBitmap = new Bitmap(256, 192, PixelFormat.Format32bppArgb);
private Task _emulatorTask;
private double TargetFrameTime = 16.667f;
public int TotalFrameCount = 0;
public double FrameTime { get; private set; } = 0;
public double FramesPerSecond { get; private set; } = 0;
private string _currentRomName = "No ROM";
private Stopwatch _stopwatch = new System.Diagnostics.Stopwatch();
public bool IsRunning { get; private set; } = false;
public ushort? Breakpoint
@@ -25,9 +29,10 @@ namespace Desktop
set { if (_machine != null) _machine.Breakpoint = value; }
}
public Form1()
public ParsonsForm1()
{
InitializeComponent();
this.Text = $"Parsons Master System 2026 - {_currentRomName}";
_machine = new SmsMachine();
PopulateIncludedRomsMenu();
@@ -46,32 +51,81 @@ namespace Desktop
// Update the PictureBox
pbScreen.Image = _screenBitmap;
TotalFrameCount++;
}
public void StartEmulator()
{
if (IsRunning) return;
IsRunning = true;
TotalFrameCount = 0;
double TargetFrameTime = 1000.0 / 60.0;
_emulatorTask = Task.Run(() =>
{
_stopwatch.Restart();
double nextFrameTargetTime = _stopwatch.Elapsed.TotalMilliseconds + TargetFrameTime;
double lastFpsUpdate = _stopwatch.Elapsed.TotalMilliseconds;
int framesThisSecond = 0;
while (IsRunning)
{
// Mark exactly when the emulator starts thinking
double frameStartTime = _stopwatch.Elapsed.TotalMilliseconds;
// 1. Do the heavy lifting (Z80 and VDP)
_machine.RunFrame();
Invoke((System.Windows.Forms.MethodInvoker)delegate { DrawScreen(); });
// 2. FIRE AND FORGET! Tell Windows to draw, but DO NOT WAIT for it to finish!
BeginInvoke((System.Windows.Forms.MethodInvoker)delegate { DrawScreen(); });
// Safety catch: If we hit a breakpoint while running, stop the loop!
// 3. Safety catch
if (_machine.Breakpoint.HasValue && _machine.Cpu.PC == _machine.Breakpoint.Value)
{
IsRunning = false;
BeginInvoke((System.Windows.Forms.MethodInvoker)delegate { _debugger?.uiUpdateTimer_Tick(null, EventArgs.Empty); });
break;
}
// Optional: Force the debugger UI to update immediately so you see it!
Invoke((System.Windows.Forms.MethodInvoker)delegate { _debugger?.uiUpdateTimer_Tick(null, EventArgs.Empty); });
// 4. Calculate TRUE Frame Time (Compute Time) BEFORE we go to sleep!
FrameTime = _stopwatch.Elapsed.TotalMilliseconds - frameStartTime;
// --- HIGH PRECISION THROTTLE ---
while (_stopwatch.Elapsed.TotalMilliseconds < nextFrameTargetTime)
{
if (nextFrameTargetTime - _stopwatch.Elapsed.TotalMilliseconds > 2.0)
{
Thread.Sleep(1);
}
else
{
// Only throttle the speed if we are actively running
Thread.Sleep(8);
Thread.SpinWait(10);
}
}
// --- METRICS MATH ---
double currentTime = _stopwatch.Elapsed.TotalMilliseconds;
TotalFrameCount++;
framesThisSecond++;
if (currentTime - lastFpsUpdate >= 1000.0)
{
FramesPerSecond = framesThisSecond / ((currentTime - lastFpsUpdate) / 1000.0);
framesThisSecond = 0;
lastFpsUpdate = currentTime;
BeginInvoke((System.Windows.Forms.MethodInvoker)delegate {
this.Text = $"Parsons Master System - {_currentRomName} [FPS/FT: {FramesPerSecond:F0}/{FrameTime:F1}]";
});
}
nextFrameTargetTime += TargetFrameTime;
if (currentTime > nextFrameTargetTime + TargetFrameTime)
{
nextFrameTargetTime = currentTime + TargetFrameTime;
}
}
});
@@ -102,8 +156,8 @@ namespace Desktop
// 3. Jam it into the Sega Mapper
_machine.LoadCartridge(rom);
// 4. Update the Window title so it looks professional
this.Text = $"Parsons Master System 2026 - {Path.GetFileNameWithoutExtension(filePath)}";
_currentRomName = Path.GetFileNameWithoutExtension(filePath);
this.Text = $"Parsons Master System - {_currentRomName}";
// 5. Turn the power on!

2
Desktop/Program.cs
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@@ -11,7 +11,7 @@ namespace Desktop
// To customize application configuration such as set high DPI settings or default font,
// see https://aka.ms/applicationconfiguration.
ApplicationConfiguration.Initialize();
Application.Run(new Form1());
Application.Run(new ParsonsForm1());
}
}
}