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/*
* Copyright (c) 1983 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that: (1) source distributions retain this entire copyright
* notice and comment, and (2) distributions including binaries display
* the following acknowledgement: ``This product includes software
* developed by the University of California, Berkeley and its contributors''
* in the documentation or other materials provided with the distribution
* and in all advertising materials mentioning features or use of this
* software. Neither the name of the University nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#ifndef lint
static char sccsid[] = "@(#)hertz.c 5.4 (Berkeley) 6/1/90";
#endif /* not lint */
#include <sys/time.h>
/*
* discover the tick frequency of the machine
* if something goes wrong, we return 0, an impossible hertz.
*/
#define HZ_WRONG 0
#ifdef __MSDOS__
#define HERTZ 18
#endif
hertz()
{
#ifdef HERTZ
return HERTZ;
#else
struct itimerval tim;
tim.it_interval.tv_sec = 0;
tim.it_interval.tv_usec = 1;
tim.it_value.tv_sec = 0;
tim.it_value.tv_usec = 0;
setitimer(ITIMER_REAL, &tim, 0);
setitimer(ITIMER_REAL, 0, &tim);
if (tim.it_interval.tv_usec < 2)
return(HZ_WRONG);
return (1000000 / tim.it_interval.tv_usec);
#endif
}
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