Generic DFA State Machine for .NET

using System;
using System.Runtime.InteropServices;
using System.ComponentModel;
using System.Threading;

namespace leppie
{
   internal class HiPerfTimer
   {
      [DllImport("Kernel32.dll")]
      private static extern bool QueryPerformanceCounter(ref long lpPerformanceCount);

      [DllImport("Kernel32.dll")]
      private static extern bool QueryPerformanceFrequency(ref long lpFrequency);

      private long startTime, stopTime;
      private long freq;

      // Constructor
      public HiPerfTimer()
      {
         startTime = 0;
         stopTime  = 0;

         if (!QueryPerformanceFrequency(ref freq))
         {
            // high-performance counter not supported
            throw new Win32Exception();
         }
      }

      // Start the timer
      public void Start()
      {
         // lets do the waiting threads there work
         Thread.Sleep(0);

         QueryPerformanceCounter(ref startTime);
      }

      // Stop the timer
      public void Stop()
      {
         QueryPerformanceCounter(ref stopTime);
      }

      // Returns the duration of the timer (in milliseconds)
      public double Duration
      {
         get
         {
            return (double)(stopTime - startTime) / freq * 1000F;
         }
      }
   }
}