feat(cli): add Raylib graphical frontend

src/Chip8.Cli/RaylibFrontend.cs

@@ -0,0 +1,149 @@
+using System;
+using System.IO;
+using Chip8.Core;
+using Raylib_cs;
+
+namespace Chip8.Cli;
+
+static class RaylibFrontend
+{
+    static readonly (int chip8Key, KeyboardKey physical)[] keyMap =
+    {
+        (0x1, KeyboardKey.KEY_ONE), (0x2, KeyboardKey.KEY_TWO), (0x3, KeyboardKey.KEY_THREE), (0xC, KeyboardKey.KEY_FOUR),
+        (0x4, KeyboardKey.KEY_Q), (0x5, KeyboardKey.KEY_W), (0x6, KeyboardKey.KEY_E), (0xD, KeyboardKey.KEY_R),
+        (0x7, KeyboardKey.KEY_A), (0x8, KeyboardKey.KEY_S), (0x9, KeyboardKey.KEY_D), (0xE, KeyboardKey.KEY_F),
+        (0xA, KeyboardKey.KEY_Z), (0x0, KeyboardKey.KEY_X), (0xB, KeyboardKey.KEY_C), (0xF, KeyboardKey.KEY_V),
+    };
+
+    static readonly Color background = new(15, 15, 20, 255);
+    static readonly Color foreground = new(180, 240, 200, 255);
+
+    public static void run(Machine machine, Options options)
+    {
+        int width = Machine.displayWidth * options.scale;
+        int height = Machine.displayHeight * options.scale;
+
+        Raylib.InitWindow(width, height, "chip8-sharp");
+        Raylib.SetTargetFPS(60);
+        Raylib.InitAudioDevice();
+
+        AudioStream beep = Raylib.LoadAudioStream(44100, 16, 1);
+        Raylib.PlayAudioStream(beep);
+        var phase = new BeepPhase();
+
+        int frame = 0;
+        while (!Raylib.WindowShouldClose())
+        {
+            pumpInput(machine);
+            machine.runFrame(options.instructionsPerFrame);
+            feedAudio(beep, machine.soundActive, phase);
+            draw(machine, options.scale);
+
+            frame++;
+            if (options.maxFrames > 0 && frame >= options.maxFrames)
+            {
+                saveScreenshot(options.screenshotPath);
+                break;
+            }
+        }
+
+        Raylib.UnloadAudioStream(beep);
+        Raylib.CloseAudioDevice();
+        Raylib.CloseWindow();
+    }
+
+    static void saveScreenshot(string? path)
+    {
+        if (path is null)
+        {
+            return;
+        }
+
+        string fileName = Path.GetFileName(path);
+        Raylib.TakeScreenshot(fileName);
+
+        string produced = Path.Combine(Directory.GetCurrentDirectory(), fileName);
+        string target = Path.GetFullPath(path);
+        if (produced != target)
+        {
+            File.Move(produced, target, overwrite: true);
+        }
+    }
+
+    static void pumpInput(Machine machine)
+    {
+        foreach ((int chip8Key, KeyboardKey physical) in keyMap)
+        {
+            if (Raylib.IsKeyDown(physical))
+            {
+                machine.pressKey(chip8Key);
+            }
+            else
+            {
+                machine.releaseKey(chip8Key);
+            }
+        }
+    }
+
+    static void draw(Machine machine, int scale)
+    {
+        Raylib.BeginDrawing();
+        Raylib.ClearBackground(background);
+
+        for (int y = 0; y < Machine.displayHeight; y++)
+        {
+            for (int x = 0; x < Machine.displayWidth; x++)
+            {
+                if (machine.display[y * Machine.displayWidth + x])
+                {
+                    Raylib.DrawRectangle(x * scale, y * scale, scale, scale, foreground);
+                }
+            }
+        }
+
+        Raylib.EndDrawing();
+    }
+
+    static void feedAudio(AudioStream beep, bool active, BeepPhase phase)
+    {
+        const int sampleRate = 44100;
+        const int toneHz = 440;
+        const short amplitude = 4000;
+        int samplesPerHalfPeriod = sampleRate / (toneHz * 2);
+
+        while (Raylib.IsAudioStreamProcessed(beep))
+        {
+            var buffer = new short[512];
+            for (int n = 0; n < buffer.Length; n++)
+            {
+                if (!active)
+                {
+                    buffer[n] = 0;
+                    continue;
+                }
+
+                buffer[n] = phase.high ? amplitude : (short)-amplitude;
+                phase.counter++;
+                if (phase.counter >= samplesPerHalfPeriod)
+                {
+                    phase.counter = 0;
+                    phase.high = !phase.high;
+                }
+            }
+
+            unsafe
+            {
+                fixed (short* samples = buffer)
+                {
+                    Raylib.UpdateAudioStream(beep, samples, buffer.Length);
+                }
+            }
+        }
+    }
+
+    sealed class BeepPhase
+    {
+        public int counter;
+        public bool high;
+    }
+}