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      1 /*	$NetBSD: ualarm.c,v 1.11 2012/06/25 22:32:44 abs 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. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "@(#)ualarm.c	8.1 (Berkeley) 6/4/93";
     36 #else
     37 __RCSID("$NetBSD: ualarm.c,v 1.11 2012/06/25 22:32:44 abs Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 #include <sys/time.h>
     43 #include <unistd.h>
     44 
     45 #ifdef __weak_alias
     46 __weak_alias(ualarm,_ualarm)
     47 #endif
     48 
     49 #define	USPS	1000000		/* # of microseconds in a second */
     50 
     51 /*
     52  * Generate a SIGALRM signal in ``usecs'' microseconds.
     53  * If ``reload'' is non-zero, keep generating SIGALRM
     54  * every ``reload'' microseconds after the first signal.
     55  */
     56 useconds_t
     57 ualarm(useconds_t usecs, useconds_t reload)
     58 {
     59 	struct itimerval new, old;
     60 
     61 	new.it_interval.tv_usec = reload % USPS;
     62 	new.it_interval.tv_sec = reload / USPS;
     63 
     64 	new.it_value.tv_usec = usecs % USPS;
     65 	new.it_value.tv_sec = usecs / USPS;
     66 
     67 	if (setitimer(ITIMER_REAL, &new, &old) == 0)
     68 		return (useconds_t)(old.it_value.tv_sec * USPS +
     69 		    old.it_value.tv_usec);
     70 
     71 	return (useconds_t)-1;
     72 }
     73