This class implements a high resolution timer capable of measuring time intervals with a resolution of some microseconds. More...

#include <jkqtphighrestimer.h>

Public Member Functions
	JKQTPHighResTimer ()
	class constructor.

	~JKQTPHighResTimer ()
	class destructor

double	getTime ()
	get the time since the last call of start() in microseconds

void	start ()
	start the timer

Protected Attributes
double	freq
	internal: timer frequency

std::chrono::system_clock::time_point	last

Detailed Description

This class implements a high resolution timer capable of measuring time intervals with a resolution of some microseconds.

Attention: Note that this is a MS Windows specific implementation od a high-resolution timer using some of windows' API methods (namely QueryPerformanceCounter() and QueryPerformanceFrequency() ). So if you want to use this class on non-win32 systems you will have to find a way to implement it for your system!!!; Also note that a standard windows system is NOT a real time OS. So do not expect to get a high accuracy when timing operations using this timer. It gives you an accurate time stamp, but it can not guarantee when the code is executed!

The timer works very simple:

you can start the timer with start() which means you set a time=0
then you can query the time difference to the last call of start() by using getTime().

win32 implementation issues:

To implement this timer on windows systems I use two API calls from the windows kernel. They are:

The first one is used to read times: In the start() method we simply save the current counter value to a variable. In getTime() we can then again use QueryPerformanceCounter() to get the current counter value and then calculate the difference between these two. Using QueryPerformanceFrequency() we can calculate the time difference in usecs from the counter value difference using:

$\Delta t=\frac{N_{\mbox{now}}-N_{\mbox{start}}}{\mbox{\texttt{QueryPerformanceFrequency()}}}\cdot 10^{6}$

Constructor & Destructor Documentation

◆ JKQTPHighResTimer()

JKQTPHighResTimer::JKQTPHighResTimer ( )

class constructor.

◆ ~JKQTPHighResTimer()

JKQTPHighResTimer::~JKQTPHighResTimer ( )

class destructor

Member Function Documentation

◆ getTime()

double JKQTPHighResTimer::getTime ( )

get the time since the last call of start() in microseconds

◆ start()

void JKQTPHighResTimer::start ( )

start the timer

Member Data Documentation

◆ freq

double JKQTPHighResTimer::freq

protected

internal: timer frequency

◆ last

std::chrono::system_clock::time_point JKQTPHighResTimer::last