feat(core): add SUPER-CHIP/XO-CHIP extended opcodes

src/Chip8.Core/Machine.Extended.cs

@@ -0,0 +1,165 @@
+namespace Chip8.Core;
+
+public sealed partial class Machine
+{
+    bool executeExtended(ushort opcode, int x, int y, int n, byte nn, ushort nnn)
+    {
+        switch (opcode & 0xF000)
+        {
+            case 0x0000:
+                return executeSystem(opcode, n);
+
+            case 0x5000:
+                if (platform == Platform.XoChip && n == 0x2)
+                {
+                    storeRange(x, y);
+                    return true;
+                }
+                if (platform == Platform.XoChip && n == 0x3)
+                {
+                    loadRange(x, y);
+                    return true;
+                }
+                return false;
+
+            case 0xD000:
+                v[0xF] = (byte)(video.drawSprite(memory, i, v[x], v[y], n, planeMask, !quirks.clipSprites) ? 1 : 0);
+                drawPending = true;
+                return true;
+
+            case 0xF000:
+                return executeExtendedMisc(opcode, x, nn);
+
+            default:
+                return false;
+        }
+    }
+
+    bool executeSystem(ushort opcode, int n)
+    {
+        if ((opcode & 0xFFF0) == 0x00C0)
+        {
+            video.scrollDown(n, planeMask);
+            drawPending = true;
+            return true;
+        }
+
+        if ((opcode & 0xFFF0) == 0x00D0)
+        {
+            video.scrollUp(n, planeMask);
+            drawPending = true;
+            return true;
+        }
+
+        switch (opcode)
+        {
+            case 0x00E0:
+                video.clear(planeMask);
+                drawPending = true;
+                return true;
+            case 0x00FB:
+                video.scrollRight(Video.scrollStep, planeMask);
+                drawPending = true;
+                return true;
+            case 0x00FC:
+                video.scrollLeft(Video.scrollStep, planeMask);
+                drawPending = true;
+                return true;
+            case 0x00FD:
+                exited = true;
+                pc -= 2;
+                return true;
+            case 0x00FE:
+                video.setResolution(false);
+                drawPending = true;
+                return true;
+            case 0x00FF:
+                video.setResolution(true);
+                drawPending = true;
+                return true;
+            default:
+                return false;
+        }
+    }
+
+    bool executeExtendedMisc(ushort opcode, int x, byte nn)
+    {
+        if (platform == Platform.XoChip && opcode == 0xF000)
+        {
+            i = (ushort)((memory[pc] << 8) | memory[pc + 1]);
+            pc += 2;
+            return true;
+        }
+
+        if (platform == Platform.XoChip && (opcode & 0xF0FF) == 0xF001)
+        {
+            planeMask = x & 0x3;
+            return true;
+        }
+
+        if (platform == Platform.XoChip && opcode == 0xF002)
+        {
+            for (int b = 0; b < audioPattern.Length; b++)
+            {
+                audioPattern[b] = memory[(i + b) & (memory.Length - 1)];
+            }
+            return true;
+        }
+
+        switch (nn)
+        {
+            case 0x30:
+                i = (ushort)(bigFontStart + (v[x] & 0xF) * FontSet.bigGlyphBytes);
+                return true;
+            case 0x3A:
+                if (platform != Platform.XoChip)
+                {
+                    return false;
+                }
+                audioPitch = v[x];
+                return true;
+            case 0x75:
+                for (int r = 0; r <= (x & 0xF); r++)
+                {
+                    rplFlags[r] = v[r];
+                }
+                return true;
+            case 0x85:
+                for (int r = 0; r <= (x & 0xF); r++)
+                {
+                    v[r] = rplFlags[r];
+                }
+                return true;
+            default:
+                return false;
+        }
+    }
+
+    void storeRange(int x, int y)
+    {
+        int step = x <= y ? 1 : -1;
+        int addr = i;
+        for (int r = x; ; r += step)
+        {
+            memory[addr++ & (memory.Length - 1)] = v[r];
+            if (r == y)
+            {
+                break;
+            }
+        }
+    }
+
+    void loadRange(int x, int y)
+    {
+        int step = x <= y ? 1 : -1;
+        int addr = i;
+        for (int r = x; ; r += step)
+        {
+            v[r] = memory[addr++ & (memory.Length - 1)];
+            if (r == y)
+            {
+                break;
+            }
+        }
+    }
+}