///////////////////////////////////////////////////////////////////////
///  HiResTimer.cpp - High Resolution Timer                         ///
///  ver 1.1          Uses Win32 Performance Counters               ///
///                                                                 ///
///  Language:     Visual C++ 2008                                  ///
///  Platform:     Dell Dimension 9200, Windows Vista Ultimate      ///
///  Application:  CSE687 Example                                   ///
///  Author:       Jim Fawcett, CST 2-187, Syracuse Univ.           ///
///                (315) 443-3948, jfawcett@twcny.rr.com            ///
///////////////////////////////////////////////////////////////////////

#include <exception>
#include "HiResTimer.h"

namespace HRTimer
{
  //----< constructor may throw exception >--------------------------

  HiResTimer::HiResTimer()
  {
    a = b = 0UL;
    if ( QueryPerformanceFrequency((LARGE_INTEGER*)&f) == 0) 
      throw std::exception("no high resolution counter on this platform");
  }
  //----< return number of platform's hi-res counter ticks >---------

  __int64 HiResTimer::ElapsedTicks()
  {
    return (b-a);
  }
  //----< return elapsed time in microseconds >----------------------

  __int64 HiResTimer::ElapsedMicroseconds()
  {
    // pick more precise time calculation

    __int64 d = (b-a); 
    if (d < 0x10c6f7a0b5edUL) // 2^64 / 1e6
      return (d*1000000UL)/f; 
    else
      return (d/f)*1000000UL;
  }
  //----< return frequence of hi-res counter >-----------------------

  __int64 HiResTimer::Frequency()
  {
    return f;
  }
//
  //----< start timer counting >-------------------------------------

  void HiResTimer::Start()
  {
    ::Sleep(0);
    QueryPerformanceCounter((LARGE_INTEGER*)&a);
  }
  //----< stop timer counting >--------------------------------------

  __int64 HiResTimer::Stop()
  {
    QueryPerformanceCounter((LARGE_INTEGER*)&b);
    return ElapsedTicks();
  }
}
//----< test stub >--------------------------------------------------

#ifdef TEST_HIRESTIMER

#include <iostream>

using namespace HRTimer;

void main()
{
  HiResTimer timer;
  std::cout << "\n  Asking thread to sleep for 150 milliseconds\n";
  timer.Start();
  ::Sleep(150);
  timer.Stop();
  std::cout << "\n  I slept for " << timer.ElapsedMicroseconds();
  std::cout << " microseconds\n\n";
}

#endif