C timers

[christianlee]

Hi all,
Has anybody a samples how to write an application with timers in C, i need two timers which doing something with different ticks.
I've used this code below:

Code: Select all

#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <sys/time.h>

void timer_handler (int signum)
{
 static int count = 0;
 printf ("timer expired %d times\n", ++count);
}

int main ()
{
 struct sigaction sa;
 struct itimerval timer;

 /* Install timer_handler as the signal handler for SIGVTALRM. */
 memset (&sa, 0, sizeof (sa));
 sa.sa_handler = &timer_handler;
 sigaction (SIGVTALRM, &sa, NULL);

 /* Configure the timer to expire after 250 msec... */
 timer.it_value.tv_sec = 0;
 timer.it_value.tv_usec = 250000;
 /* ... and every 250 msec after that. */
 timer.it_interval.tv_sec = 0;
 timer.it_interval.tv_usec = 250000;
 /* Start a virtual timer. It counts down whenever this process is
   executing. */
 setitimer (ITIMER_VIRTUAL, &timer, NULL);

 /* Do busy work. */
 while (1);
}

but there're only one timer and I need two
Thanks, chris.

[iTux]

I think you can have only one timer signal...

If you cannot find a way to get more, you can implement more timers in your program...


If your time are:
3 4 --> set it to 1 and when interrupted maintained the count: 1, 2, 3, 4
4 6 --> set it to 2: 2, 4, 6
12 18 --> set it to 6: 6, 12, 18

Basically greatest common divisor of your times. You might be interrupt for nothing, but anyway.


iTux

[Sleeper]

You can also build your own timer framework. Having a single base time marker (i.e for example a tick every 10ms), and a separate thread being wake up on these ticks, and handling an ordered list of timers that are expiring ..; Something along this line ...