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

namespace Win32
{
  internal class HiPerfTimer
  {
    [DllImport("Kernel32.dll")]
    private static extern bool QueryPerformanceCounter(
      out long lpPerformanceCount);

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

    private long startTime, stopTime;
    private long freq;

    // Constructor

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

      if (QueryPerformanceFrequency(out freq) == false)
      {
        // 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(out startTime);
    }

    // Stop the timer

    public void Stop()
    {
      QueryPerformanceCounter(out stopTime);
    }

    // Returns the duration of the timer (in seconds)

    public double Duration
    {
      get
      {
        return (double)(stopTime - startTime) / (double) freq;
      }
    }
  }
}