mirror of
https://github.com/jkriege2/JKQtPlotter.git
synced 2024-11-15 18:15:52 +08:00
115 lines
4.0 KiB
C++
115 lines
4.0 KiB
C++
/*
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Copyright (c) 2008-2024 Jan W. Krieger (<jan@jkrieger.de>) (DKFZ) & IWR, University of Heidelberg
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last modification: $LastChangedDate: 2015-06-10 19:19:10 +0200 (Mi, 10 Jun 2015) $ (revision $Rev: 3976 $)
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This software is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License (LGPL) as published by
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the Free Software Foundation, either version 2.1 of the License, or
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(at your option) any later version.
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This program 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
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GNU Lesser General Public License (LGPL) for more details.
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You should have received a copy of the GNU Lesser General Public License (LGPL)
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <cmath>
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#include <cstdlib>
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#include <iostream>
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#include <chrono>
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#include "jkqtcommon_imexport.h"
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#ifndef __WINDOWS__
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# if defined(WIN32) || defined(WIN64) || defined(_MSC_VER) || defined(_WIN32)
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# define __WINDOWS__
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# endif
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#endif
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#ifndef __LINUX__
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# if defined(linux)
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# define __LINUX__
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# endif
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#endif
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#if defined(__WINDOWS__)
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#include<windows.h>
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#elif defined(__LINUX__)
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#include <sys/time.h>
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#else
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#include <sys/time.h>
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#endif
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#ifndef JKQTPHIGHRESTIMER_H
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#define JKQTPHIGHRESTIMER_H
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/**
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* \brief This class implements a high resolution timer capable of measuring time intervals with a resolution
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* of some microseconds
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* \ingroup jkqtptools_debugging
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*
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* \attention Note that this is a MS Windows specific implementation od a high-resolution timer using some of
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* windows' API methods (namely \c QueryPerformanceCounter() and \c QueryPerformanceFrequency() ). So if you want
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* to use this class on non-win32 systems you will have to find a way to implement it for your system!!!
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*
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* \attention Also note that a standard windows system is NOT a real time OS. So do not expect to get a high accuracy
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* when timing operations using this timer. It gives you an accurate time stamp, but it can not guarantee when
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* the code is executed!
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*
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*
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* The timer works very simple:
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* - you can start the timer with start() which means you set a time=0
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* - then you can query the time difference to the last call of start() by using getTime().
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* .
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*
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*
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* \par win32 implementation issues:
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* To implement this timer on windows systems I use two API calls from the windows kernel. They are:
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* <ul>
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* <li> <a href="http://msdn2.microsoft.com/en-us/library/ms644904.aspx">QueryPerformanceCounter()</a>
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* <li> <a href="http://msdn2.microsoft.com/en-us/library/ms644905.aspx">QueryPerformanceFrequency()</a>
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* </ul>
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* \n
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* The first one is used to read times: In the start() method we simply save the current counter value to a variable.
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* In getTime() we can then again use QueryPerformanceCounter() to get the current counter value and then calculate
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* the difference between these two. Using QueryPerformanceFrequency() we can calculate the time difference in usecs
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* from the counter value difference using:
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* \f[ \Delta t=\frac{N_{\mbox{now}}-N_{\mbox{start}}}{\mbox{\texttt{QueryPerformanceFrequency()}}}\cdot 10^{6} \f]
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*
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*/
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class JKQTCOMMON_LIB_EXPORT JKQTPHighResTimer {
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protected:
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#ifdef __WINDOWS__
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/** \brief internal: time stamp of the last call of start() */
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LARGE_INTEGER last;
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#else
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std::chrono::system_clock::time_point last;
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#endif
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/** \brief internal: timer frequency */
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double freq;
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public:
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/** \brief class constructor. */
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JKQTPHighResTimer();
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/** \brief class destructor */
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~JKQTPHighResTimer();
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/** \brief start the timer */
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void start();
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/** \brief get the time since the last call of start() in microseconds */
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double getTime();
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};
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#endif // JKQTPHIGHRESTIMER_H
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