/* * Copyright (c) 1983 Regents of the University of California. * All rights reserved. * * Redistribution and use in source and binary forms are permitted * provided that the above copyright notice and this paragraph are * duplicated in all such forms and that any documentation, * advertising materials, and other materials related to such * distribution and use acknowledge that the software was developed * by the University of California, Berkeley. The name of the * University may not 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 MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. */ #ifndef lint static char sccsid[] = "@(#)hertz.c 5.3 (Berkeley) 06/29/88"; #endif /* not lint */ #include /* * discover the tick frequency of the machine * if something goes wrong, we return 0, an impossible hertz. */ #define HZ_WRONG 0 hertz() { 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); }