NAME
ualarm — set the interval timer
SYNOPSIS
#include <unistd.h>
useconds_t ualarm(useconds_t useconds, useconds_t interval);
DESCRIPTION
The
ualarm()
function causes the
SIGALRM
signal to be generated for the calling process after the
number of real-time microseconds specified by the
useconds
argument has elapsed. When the
interval
argument is non-zero,
repeated timeout notification occurs with a period in microseconds
specified by the
interval
argument. If the notification signal,
SIGALRM,
is not caught or ignored, the calling process is terminated.
Implementations may place limitations on the
granularity of timer values. For each interval
timer, if the requested timer value requires a finer
granularity than the implementation supports, the
actual timer value will be rounded up to the next
supported value.
Interactions between
ualarm()
and either
alarm()
or
sleep()
are unspecified.
RETURN VALUE
The
ualarm()
function returns the number of microseconds remaining from the previous
ualarm()
call. If no timeouts are pending or if
ualarm()
has not previously been called,
ualarm()
returns 0.
ERRORS
No errors are defined.
APPLICATION USAGE
The
ualarm()
function is a simplified interface to
setitimer(),
and uses the
ITIMER_REAL
interval timer.
CHANGE HISTORY
First released in Issue 4, Version 2.
