/* QueryPerformanceTimerTest01
 * 
 * By Philip Hagen
 * phil [AT] evilpixel.org
 * 20 August 2006
 * 
 * This console application tests the QueryPerformanceCounter() and QueryPerformanceFrequency()
 * Windows API methods.
 */ 

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices; // for DllImport attribute

namespace PhilipHagen.QueryPerformanceTimerTest01
{
  class QueryPerformanceTimerTestProgram
  {
    /// <summary>
    /// Number of seconds to run this test for.
    /// </summary>
    private const int SecondsToRun = 3;

    static void Main(string[] args)
    {
      Console.ForegroundColor = ConsoleColor.Gray;
      Console.WriteLine("*** QueryPerformanceTimerTest01 ***");
      Console.WriteLine("By Philip Hagen, 20 August 2006");
      Console.WriteLine();

      // Query the frequency of the high performance counter (in ticks per second)
      // and determine if this system supports high-performance timers.
      long frequency = 0;
      bool supported = QueryPerformanceFrequency(out frequency);

      // If high-performance timers are not supported, inform the user and exit..
      if (!supported)
      {
        Console.WriteLine("Your system does not support high performance timers.");

        // Wait for keypress from user before terminating.
        Console.WriteLine();
        Console.WriteLine("Press a key to finish...");
        Console.ReadKey(true);
        return;
      }

      Console.WriteLine(string.Format("Timer frequency = {0} updates per second", frequency));
      Console.WriteLine("Running test for " + SecondsToRun + " seconds...");
      Console.WriteLine();

      DateTime startTime = DateTime.Now;
      TimeSpan timeToRunFor = new TimeSpan(0, 0, SecondsToRun);
      DateTime endTime = startTime.Add(timeToRunFor);

      // Stores the number of ticks in the previous frame.
      long ticksLast = 0;
      // Stores the number of ticks now.
      long ticks = 0;

      // Stores the total number of ticks.
      long totalTickCount = 0;
      // Stores the number of bad ticks.
      long badTickCount = 0;

      QueryPerformanceCounter(out ticks);
      
      // Keep looping until the desired time has passed.
      while (DateTime.Now < endTime)
      {
        ++totalTickCount;
                
        ticksLast = ticks;

        // Get current counter value.
        QueryPerformanceCounter(out ticks);

        if (ticks > ticksLast)
        {
          // Ticks are larger than previous; as expected!
          Console.ForegroundColor = ConsoleColor.Green;
        }
        else
        {
          // Ticks are less than previous!!!
          Console.ForegroundColor = ConsoleColor.Red;

          ++badTickCount;
        }

        Console.WriteLine(string.Format("Ticks = {0} (difference = {1:0})", ticks, ticks - ticksLast));
      }

      Console.ForegroundColor = ConsoleColor.Gray;

      // Print summary results.
      Console.WriteLine();
      Console.WriteLine(string.Format("Timer frequency was reported as {0} ticks per second", frequency));
      string resultString = string.Format("In {0} seconds of testing, {1} of {2} measurements were bad ({3:0.00}%).",
        SecondsToRun, badTickCount, totalTickCount, (float)badTickCount / (float)totalTickCount * 100.0f);
      Console.WriteLine(resultString);
      
      // Wait for keypress from user before terminating.
      Console.WriteLine();
      Console.WriteLine("Press a key to finish...");
      Console.ReadKey(true);
    }

    /// <summary>
    /// Obtains the current high-performance timer ticks value.
    /// </summary>
    /// <param name="lpPerformanceCount">Will be set to the current timer ticks.</param>
    /// <returns>True if the system contains a high-performance timer, false if it doesn't.</returns>
    [DllImport("Kernel32.dll")]
    private static extern bool QueryPerformanceCounter(
        out long lpPerformanceCount);

    /// <summary>
    /// Obtains the frequency of the system's high-performance timer. This value indicates the number
    /// of times the high-performance timer increments itself every second.
    /// </summary>
    /// <param name="lpFrequency">Will be set to the frequency of the high-performance timer.</param>
    /// <returns>True if the system contains a high-performance timer, false if it doesn't.</returns>
    [DllImport("Kernel32.dll")]
    private static extern bool QueryPerformanceFrequency(
        out long lpFrequency);
  }
}