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ualarm.c revision 1.3 
      1 /*
      2  * Copyright (c) 1985 Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #if defined(LIBC_SCCS) && !defined(lint)
     35 /*static char *sccsid = "from: @(#)ualarm.c	5.5 (Berkeley) 2/23/91";*/
     36 static char *rcsid = "$Id: ualarm.c,v 1.3 1993/08/26 00:45:21 jtc Exp $";
     37 #endif /* LIBC_SCCS and not lint */
     38 
     39 #include <sys/time.h>
     40 #include <unistd.h>
     41 
     42 #define	USPS	1000000		/* # of microseconds in a second */
     43 
     44 /*
     45  * Generate a SIGALRM signal in ``usecs'' microseconds.
     46  * If ``reload'' is non-zero, keep generating SIGALRM
     47  * every ``reload'' microseconds after the first signal.
     48  */
     49 unsigned
     50 ualarm(usecs, reload)
     51 	register unsigned usecs;
     52 	register unsigned reload;
     53 {
     54 	struct itimerval new, old;
     55 
     56 	new.it_interval.tv_usec = reload % USPS;
     57 	new.it_interval.tv_sec = reload / USPS;
     58 
     59 	new.it_value.tv_usec = usecs % USPS;
     60 	new.it_value.tv_sec = usecs / USPS;
     61 
     62 	if (setitimer(ITIMER_REAL, &new, &old) == 0)
     63 		return (old.it_value.tv_sec * USPS + old.it_value.tv_usec);
     64 	/* else */
     65 		return (-1);
     66 }
     67