Clock.cs

using System;
using System.Diagnostics;
using System.Threading;
using System.Threading.Tasks;

namespace Chip8
{
    public class Clock
    {
        // = (TimeSpan.TicksPerSecond / 500)
        const int ticksPer500Hz = 20_000;

        // = (TimeSpan.TicksPerSecond / 60)
        const int ticksPer60Hz = 166_666;

        private readonly Task thread;
        private readonly Action tick60Hz;
        private readonly Action tick500Hz;
        private readonly Stopwatch stopwatch;

        private long last60Hz = 0;
        private long last500Hz = 0;

        public Clock(Action tick60Hz, Action tick500Hz, bool running = true)
        {
            stopwatch = Stopwatch.StartNew();
            this.tick60Hz = tick60Hz;
            this.tick500Hz = tick500Hz;

            Running = running;
            thread = Task.Run(Loop);
        }

        public bool Running { get; set; }

        private void Loop()
        {
            while (true)
            {
                if (stopwatch.ElapsedTicks - last500Hz > ticksPer500Hz)
                {
                    last500Hz = stopwatch.ElapsedTicks;
                    if (Running)
                    {
                        tick500Hz();
                    }
                }

                if (stopwatch.ElapsedTicks - last60Hz > ticksPer60Hz)
                {
                    last60Hz = stopwatch.ElapsedTicks;
                    tick60Hz();
                }

                var sleepFor = TimeSpan.FromTicks(Math.Min(0, stopwatch.ElapsedTicks - last500Hz));
                Thread.Sleep(sleepFor);
            }
        }
    }
}