//////////////////////////////////////////////////////////////////////////////
//
//   Copyright (C) 2006  by Diether Knof
//
//   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; version 2 of 
//   the License.
//
//   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 can find this license in the file 'gpl.txt'.
//
//   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
//
//  Contact:
//    Diether Knof dknof@gmx.de
//
//////////////////////////////////////////////////////////////////////////////

#include "stop_watch.h"

#include <iostream>
using namespace std;

namespace DK {
  namespace Utils {

    /**
     ** -> result
     **
     ** @param     start_time   start time
     **
     ** @return    difference from 'start_time' to 'now'
     **            '0' on error
     **
     ** @author    Diether Knof
     **
     ** @version   2006-10-29
     **/
    MSecCounter
      StopWatch::diff_to_now(clock_t const start_time) {
        clock_t const stop_time = clock();
        if (stop_time == static_cast<clock_t>(-1)) {
          cerr << "StopWatch::diff_to_now()\n"
            << "  could not get time"
            << endl;
          return 0;
        }

        if (start_time > stop_time) {
          cerr << "StopWatch::diff_to_now()\n"
            << "  overflow: "
            << "start time = " << start_time
            << " > " << stop_time << " = stop time"
            << endl;
          return 0;
        }

        // under Microsoft Windows 'CLOCKS_PER_SEC' is 1000,
        // under GNU/Linux (Posix) 1000000,
        // under FreeBSD < 1000
        // So in order to do integer calculation we have to split the code

        // The variable is needed because 'CLOCKS_PER_SEC' need not to be a
        // constant (so no '#if CLOCKS_PER_SEC < 1000' can be used).
        // But with a constant in FreeBSD 'CLOCKS_PER_SEC / 1000' equals 0,
        // this leads to the warning division with zero (g++-3.4.4).
        clock_t clocks_per_sec = CLOCKS_PER_SEC;
        if (clocks_per_sec < 1000) {
          return ((stop_time - start_time) * (1000 / clocks_per_sec));
        } else {
          return ((stop_time - start_time) / (clocks_per_sec / 1000));
        }
      } // static MSecCounter StopWatch::diff_to_now(clock_t start_time)


    /**
     ** constructor
     **
     ** @param     -
     **
     ** @return    -
     ** 
     ** @author    Diether Knof
     **
     ** @version   2006-10-29
     **/
    StopWatch::StopWatch() :
      start_time(-1),
      msec_(0)
    { }

    /**
     ** destructor
     **
     ** @param     -
     **
     ** @return    -
     ** 
     ** @author    Diether Knof
     **
     ** @version   2006-10-29
     **/
    StopWatch::~StopWatch()
    { }

    /**
     ** start the time counter
     **
     ** @param     -
     **
     ** @return    -
     ** 
     ** @author    Diether Knof
     **
     ** @version   2006-10-29
     **/
    void
      StopWatch::start()
      {
        this->start_time = clock();
        if (this->start_time == static_cast<clock_t>(-1)) {
          cerr << "StopWatch::stop()\n"
            << "clock could not be started"
            << endl;
          return ;
        }
        return ;
      } // void StopWatch::start()

    /**
     ** stop the time counter
     **
     ** @param     -
     **
     ** @return    -
     ** 
     ** @author    Diether Knof
     **
     ** @version   2006-10-29
     **/
    void
      StopWatch::stop()
      {
        if (this->start_time == static_cast<clock_t>(-1)) {
          cerr << "StopWatch::stop()\n"
            << "clock not started"
            << endl;
          (*reinterpret_cast<int*>(NULL) = 0);
          return ;
        }

        this->msec_ += StopWatch::diff_to_now(this->start_time);

        this->start_time = static_cast<clock_t>(-1);

        return ;
      } // void StopWatch::stop()

    /**
     ** reset the counter
     **
     ** @param     -
     **
     ** @return    -
     ** 
     ** @author    Diether Knof
     **
     ** @version   2006-10-29
     **/
    void
      StopWatch::reset()
      {
        this->start_time = static_cast<clock_t>(-1);
        this->msec_ = 0;
        return ;
      } // void StopWatch::reset()

    /**
     ** -> result
     **
     ** @param     -
     **
     ** @return    whether the stop watch is running
     ** 
     ** @author    Diether Knof
     **
     ** @version   2006-10-29
     **/
    bool
      StopWatch::running() const
      {
        return (this->start_time != static_cast<clock_t>(-1));
      } // bool StopWatch::running() const

    /**
     ** -> result
     **
     ** @param     -
     **
     ** @return    the stopped time in miliseconds
     ** 
     ** @author    Diether Knof
     **
     ** @version   2006-10-29
     **/
    MSecCounter
      StopWatch::msec() const
      {
        if (this->start_time != static_cast<clock_t>(-1))
        return this->msec_ + StopWatch::diff_to_now(this->start_time);
        else
        return this->msec_;
      } // MSecCounter StopWatch::msec() const

  } // namespace Utils
} // namespace DK