Game/Snake.cs

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struct Snake
{
    public const int MaxLength = 30;

    private int _length;

    // Body is a packed integer that packs the X coordinate, Y coordinate, and the character
    // for the snake's body.
    // Only primitive types can be used with C# `fixed`, hence this is an `int`.
    private unsafe fixed int _body[MaxLength];

    private Direction _direction;
    private Direction _oldDirection;

    public Direction Course
    {
        set
        {
            if (_oldDirection != _direction)
                _oldDirection = _direction;

            if (_direction - value != 2 && value - _direction != 2)
                _direction = value;
        }
    }

    public unsafe Snake(byte x, byte y, Direction direction)
    {
        _body[0] = new Part(x, y, DirectionToChar(direction, direction)).Pack();
        _direction = direction;
        _oldDirection = direction;
        _length = 1;
    }

    public unsafe bool Update()
    {
        Part oldHead = Part.Unpack(_body[0]);
        Part newHead = new Part(
            (byte)(_direction switch
            {
                Direction.Left => oldHead.X == 0 ? FrameBuffer.Width - 1 : oldHead.X - 1,
                Direction.Right => (oldHead.X + 1) % FrameBuffer.Width,
                _ => oldHead.X,
            }),
            (byte)(_direction switch
            {
                Direction.Up => oldHead.Y == 0 ? FrameBuffer.Height - 1 : oldHead.Y - 1,
                Direction.Down => (oldHead.Y + 1) % FrameBuffer.Height,
                _ => oldHead.Y,
            }),
            DirectionToChar(_direction, _direction)
            );

        oldHead = new Part(oldHead.X, oldHead.Y, DirectionToChar(_oldDirection, _direction));

        bool result = true;

        for (int i = 0; i < _length - 1; i++)
        {
            Part current = Part.Unpack(_body[i]);