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ualarm.c revision 1.5 
      1 /*	$NetBSD: ualarm.c,v 1.5 1997/07/13 19:46:24 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1985, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 #if 0
     39 static char sccsid[] = "@(#)ualarm.c	8.1 (Berkeley) 6/4/93";
     40 #else
     41 __RCSID("$NetBSD: ualarm.c,v 1.5 1997/07/13 19:46:24 christos Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #include <sys/time.h>
     46 #include <unistd.h>
     47 
     48 #define	USPS	1000000		/* # of microseconds in a second */
     49 
     50 /*
     51  * Generate a SIGALRM signal in ``usecs'' microseconds.
     52  * If ``reload'' is non-zero, keep generating SIGALRM
     53  * every ``reload'' microseconds after the first signal.
     54  */
     55 unsigned
     56 ualarm(usecs, reload)
     57 	register unsigned usecs;
     58 	register unsigned reload;
     59 {
     60 	struct itimerval new, old;
     61 
     62 	new.it_interval.tv_usec = reload % USPS;
     63 	new.it_interval.tv_sec = reload / USPS;
     64 
     65 	new.it_value.tv_usec = usecs % USPS;
     66 	new.it_value.tv_sec = usecs / USPS;
     67 
     68 	if (setitimer(ITIMER_REAL, &new, &old) == 0)
     69 		return (old.it_value.tv_sec * USPS + old.it_value.tv_usec);
     70 	/* else */
     71 		return (-1);
     72 }
     73