// Stopwatch.h: interface for the CStopwatch class.
//
/////////////////////////////////////////////////////////////////////

#if !defined(STOPWATCH_H)
#define STOPWATCH_H

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#include <windows.h>	// has class definition of IUnknown 

class IStopwatch : public IUnknown
{
public:
  // Stopwatch specific functions
  virtual HRESULT __stdcall Start() =0;
  virtual HRESULT __stdcall ElapsedTime(float *Time) =0;
};

class CStopwatch : public IStopwatch  
{
public:
	CStopwatch();
	virtual ~CStopwatch();

private:
  // Reference counting
  long m_nReferenceCount;

  // The frequency of the counter 
  // returned by QueryPerformanceCounter()
  LARGE_INTEGER m_nFrequency;

  // The counter value when the start method was last called.
  LARGE_INTEGER m_nStartTime;

public:
  // IUnknown methods
  HRESULT __stdcall QueryInterface(
    REFIID riid,
    void **ppvObject);
  unsigned long __stdcall AddRef();
  unsigned long __stdcall Release();

  // IStopwatch specific functions
  HRESULT __stdcall Start();
  HRESULT __stdcall ElapsedTime(float *Time);

};

#endif // !defined(STOPWATCH_H)