simple use of the interval timer

/*

• setitimer.c - simple use of the interval timer */

#include <sys/time.h> /* for setitimer / #include <unistd.h> / for pause / #include <signal.h> / for signal */

#define INTERVAL 500 /* number of milliseconds to go off */

/* function prototype */ void DoStuff(void);

int main(int argc, char *argv[]) {

struct itimerval it_val; /* for setting itimer */

/* Upon SIGALRM, call DoStuff().

• Set interval timer. We want frequency in ms,
• but the setitimer call needs seconds and useconds. / if (signal(SIGALRM, (void ()(int)) DoStuff) == SIG_ERR) { perror("Unable to catch SIGALRM"); exit(1); } it_val.it_value.tv_sec = INTERVAL/1000; it_val.it_value.tv_usec = (INTERVAL*1000) % 1000000; it_val.it_interval = it_val.it_value; if (setitimer(ITIMER_REAL, &it_val, NULL) == -1) { perror("error calling setitimer()"); exit(1); }

while (1) pause();

}

/*

• DoStuff */ void DoStuff(void) {

printf("Timer went off.\n");

}