feat(core): add font set, quirks config, and save-state snapshot

src/Chip8.Core/MachineSnapshot.cs

@@ -0,0 +1,71 @@
+using System;
+using System.Globalization;
+using System.Text;
+
+namespace Chip8.Core;
+
+public sealed class MachineSnapshot
+{
+    public ushort pc { get; init; }
+    public ushort i { get; init; }
+    public byte sp { get; init; }
+    public byte delayTimer { get; init; }
+    public byte soundTimer { get; init; }
+    public int planeMask { get; init; }
+    public bool hires { get; init; }
+    public bool exited { get; init; }
+    public byte[] v { get; init; } = Array.Empty<byte>();
+    public ushort[] stack { get; init; } = Array.Empty<ushort>();
+
+    public static MachineSnapshot capture(Machine machine)
+    {
+        var stackFrames = new ushort[machine.sp];
+        Array.Copy(machine.stack, stackFrames, machine.sp);
+        return new MachineSnapshot
+        {
+            pc = machine.pc,
+            i = machine.i,
+            sp = machine.sp,
+            delayTimer = machine.delayTimer,
+            soundTimer = machine.soundTimer,
+            planeMask = machine.planeMask,
+            hires = machine.hires,
+            exited = machine.exited,
+            v = (byte[])machine.v.Clone(),
+            stack = stackFrames,
+        };
+    }
+
+    public string format()
+    {
+        var builder = new StringBuilder();
+        builder.Append("PC=0x").Append(pc.ToString("X4", CultureInfo.InvariantCulture));
+        builder.Append(" I=0x").Append(i.ToString("X4", CultureInfo.InvariantCulture));
+        builder.Append(" SP=").Append(sp);
+        builder.Append(" DT=").Append(delayTimer);
+        builder.Append(" ST=").Append(soundTimer);
+        builder.Append(" plane=").Append(planeMask);
+        builder.Append(" hires=").Append(hires ? "1" : "0");
+        builder.Append('\n');
+
+        for (int register = 0; register < v.Length; register++)
+        {
+            builder.Append('V').Append(register.ToString("X1", CultureInfo.InvariantCulture));
+            builder.Append('=').Append(v[register].ToString("X2", CultureInfo.InvariantCulture));
+            builder.Append((register & 0x7) == 0x7 ? '\n' : ' ');
+        }
+
+        builder.Append("stack=[");
+        for (int frame = 0; frame < stack.Length; frame++)
+        {
+            if (frame > 0)
+            {
+                builder.Append(' ');
+            }
+            builder.Append("0x").Append(stack[frame].ToString("X4", CultureInfo.InvariantCulture));
+        }
+        builder.Append("]\n");
+
+        return builder.ToString();
+    }
+}