/**
    \file Timer.h
    Header file for Timer class.

    \author George J. Grevera, Ph.D., ggrevera@sju.edu

    Copyright (C) 2002, George J. Grevera

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
    USA or from http://www.gnu.org/licenses/gpl.txt.

    This General Public License does not permit incorporating this
    code into proprietary programs.  (So a hypothetical company such
    as GH (Generally Hectic) should NOT incorporate this code into
    their proprietary programs.)
 */
#ifndef Timer_h
#define Timer_h
//----------------------------------------------------------------------
/// Timer class for reporting elapsed time and CPU time.
class Timer {
  private:
    double    mStart;
    FILETIME  mKernelTime, mUserTime;

  public:
    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    inline Timer ( ) {
	    reset();
	}
    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    /// reset timer to 0.
    inline void reset ( void ) {
        mStart = GetTickCount();

        FILETIME  creationTime, exitTime;
        GetProcessTimes( GetCurrentProcess(), &creationTime, &exitTime,
                         &mKernelTime, &mUserTime );
    }
    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    /// return elapsed time in seconds.
    inline double getElapsedTime ( void ) {
        long  tc_end = GetTickCount();
        return  (tc_end-mStart) / 1E3;
    }
    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    /// return actual cpu time used.
    inline double getCPUTime ( void ) {
        FILETIME  creationTime, exitTime, kernelTime, userTime;
        GetProcessTimes( GetCurrentProcess(), &creationTime, &exitTime,
                         &kernelTime, &userTime );
        //as recommended by bill:
        // http://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/base/filetime_str.asp
        ULARGE_INTEGER  u2;
        memcpy( &u2, &userTime, sizeof(userTime) );
        __int64*  i2 = (__int64*)&u2;
        ULARGE_INTEGER  u1;
        memcpy( &u1, &mUserTime, sizeof(mUserTime) );
        __int64*  i1 = (__int64*)&u1;
        __int64   i3 = *i2 - *i1;
        //from http://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/base/filetime_str.asp
        // The FILETIME structure is a 64-bit value representing the number of 100-nanosecond intervals since January 1, 1601 (UTC).
        const double  userCPUTime = i3 * 100 / 1E9;

        //determine kernel cpu time
        memcpy( &u2, &kernelTime, sizeof(kernelTime) );
        i2 = (__int64*)&u2;
        memcpy( &u1, &mKernelTime, sizeof(mKernelTime) );
        i1 = (__int64*)&u1;
        i3 = *i2 - *i1;
        const double  kernelCPUTime = i3 * 100 / 1E9;

        return userCPUTime + kernelCPUTime;
    }
    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
};

#endif
//----------------------------------------------------------------------