92 lines
4.2 KiB
C++
92 lines
4.2 KiB
C++
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/*
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* Portable Agile C++ Classes (PACC)
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* Copyright (C) 2004 by Marc Parizeau
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* http://manitou.gel.ulaval.ca/~parizeau/PACC
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* Contact:
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* Laboratoire de Vision et Systemes Numeriques
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* Departement de genie electrique et de genie informatique
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* Universite Laval, Quebec, Canada, G1K 7P4
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* http://vision.gel.ulaval.ca
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*
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*/
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/*!
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* \file PACC/Util/Timer.hpp
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* \brief Class definition for the portable timer.
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* \author Marc Parizeau, Laboratoire de vision et systèmes numériques, Université Laval
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* $Revision: 1.5.2.1 $
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* $Date: 2007/09/10 18:24:10 $
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*/
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#ifndef PACC_Timer_hpp
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#define PACC_Timer_hpp
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namespace PACC {
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/*! \brief Portable timer class.
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\author Marc Parizeau, Laboratoire de vision et systèmes numériques, Université Laval
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\ingroup Util
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This class implements a simple stopwatch timer that is always running. Method Timer::getValue can be used to return the current timer value in seconds. Method Timer::reset resets this value to 0.
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By default, if possible, the class uses the CPU's high resolution hardware time-stamp to measure time. Under Windows, this always translates to a call to the QueryPerformanceCounter method. Under Unix, when using the gcc compiler, inlined assembly code is used to retrieve the hardware counter on the following platforms:
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- Pentium family (i386)
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- PowerPC family (ppc)
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.
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Otherwise, the class uses the Unix gettimeofday method to retrieve a somewhat lower resolution time stamp (max resolution is micro-seconds).
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The current high resolution time stamp can be retrieved using method Timer::getCount. The time period associated with a single count increment is platform dependent. Its value can be fetch with method Timer::getCountPeriod.
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\attention Hardware time-stamp counters may be dependent on the CPU clock frequency. Under Unix, the hardware time-stamp frequency needs to be evaluated using a calibration procedure based on method gettimeofday. If applicable, this procedure lasts about 0.1 sec when using default parameters (see Timer::calibrateCountPeriod).
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*/
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class Timer {
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public:
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/*! \brief Construct a timer and reset its value.
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On supported Unix platforms, argument \c inHardware=true (default) enables the use of the CPU's high resolution hardware time-stamp. Argument \c inHardware=false forces the use of a somewhat lower resolution count based on the Unix gettimeofday method. Note that the use of the hardware counter under Unix requires a preliminary calibration procedure (see Timer::calibrateCountPeriod).
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*/
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Timer(bool inHardware=true) : mHardware(inHardware) {
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if(mPeriod == 0) calibrateCountPeriod();
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reset();
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}
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//! Calibrate the count period.
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void calibrateCountPeriod(unsigned int inDelay=10000, unsigned int inTimes=10);
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//! Return the current high resolution count.
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unsigned long long getCount(void) const;
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//! Return the time period of a single count increment (in seconds).
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double getCountPeriod(void) const {return mPeriod;}
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//! Return the current timer value in seconds.
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double getValue(void) const {return (getCount()-mCount)*mPeriod;}
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//! reset the timer value (to 0 second).
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void reset(void) {mCount = getCount();}
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protected:
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bool mHardware; //!< Specifies whether hardware time-stamps should be used.
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unsigned long long mCount; //!< Count value at last reset.
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static double mPeriod; //!< Time period of a single count in seconds.
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};
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} // end of PACC namespace
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#endif // PACC_Timer_hpp
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