Initial commit

1 files changed, 76 insertions, 0 deletions

diff --git a/Chip/DisplayDevice.cs b/Chip/DisplayDevice.cs
new file mode 100644
index 0000000..ea34cfb
--- /dev/null
+++ b/Chip/DisplayDevice.cs
@@ -0,0 +1,76 @@
+namespace Q1Emu.Chip;
+
+using System;
+using System.Collections.Generic;
+using Microsoft.Xna.Framework;
+using Microsoft.Xna.Framework.Graphics;
+
+public class DisplayDevice : RamDevice
+{
+    public           Texture2D? OutputTexture;
+    private readonly u16        _paletteSize;
+    private readonly u16        _displayWidth;
+    private readonly u16        _displayHeight;
+
+    public DisplayDevice(u16 paletteSize, u16 displayWidth, u16 displayHeight, u16 addressableStart)
+        : base(addressableStart, DisplayDevice.DetermineSize(paletteSize, displayWidth, displayHeight))
+    {
+        this._paletteSize   = paletteSize;
+        this._displayWidth  = displayWidth;
+        this._displayHeight = displayHeight;
+    }
+
+    private static u16 DetermineSize(u16 paletteSize, u16 displayWidth, u16 displayHeight)
+    {
+        return (u16) ((paletteSize * 3) + (displayWidth * displayHeight));
+    }
+
+    public override void Clock()
+    {
+        Color[] palette = this.ReadPalette();
+        ref8 pixelData = this.ReadSeq((u16) (this.AddressableStart + this._paletteSize * 3), (u16) (this._displayWidth * this._displayHeight));
+
+        Color[] textureData = new Color[this._displayWidth * this._displayHeight];
+        for (u16 i = 0; i < textureData.Length; i++)
+        {
+            u8 pixelValue = pixelData[i];
+            textureData[i] = palette[pixelValue];
+        }
+
+        if (this.OutputTexture != null)
+            this.OutputTexture.SetData(textureData);
+    }
+
+    private Color[] ReadPalette()
+    {
+        ref8 paletteData = this.ReadSeq(this.AddressableStart, (u16) (this._paletteSize * 3));
+        Color[] colors = new Color[this._paletteSize + 1];
+        colors[0] = Color.Transparent;
+
+        for (u16 i = 0; i < this._paletteSize; i++)
+        {
+            u16 offset = (u16) (i * 3);
+            byte r = paletteData[offset];
+            byte g = paletteData[offset + 1];
+            byte b = paletteData[offset + 2];
+            colors[(u16) (i             + 1)] = new Color(r, g, b);
+        }
+
+        return colors;
+    }
+
+    public void SetPalette(Color[] palette)
+    {
+        if (palette.Length != this._paletteSize)
+            throw new ArgumentException($"Palette must have {this._paletteSize} colors.");
+
+        ref8 paletteData = this.ReadSeq(this.AddressableStart, (u16) (this._paletteSize * 3));
+        for (u16 i = 0; i < this._paletteSize; i++)
+        {
+            u16 offset = (u16) (i * 3);
+            paletteData[offset]     = palette[i].R;
+            paletteData[offset + 1] = palette[i].G;
+            paletteData[offset + 2] = palette[i].B;
+        }
+    }
+}
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