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Annotation of 43BSDReno/pgrm/gprof/hertz.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1983 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms are permitted
        !             6:  * provided that: (1) source distributions retain this entire copyright
        !             7:  * notice and comment, and (2) distributions including binaries display
        !             8:  * the following acknowledgement:  ``This product includes software
        !             9:  * developed by the University of California, Berkeley and its contributors''
        !            10:  * in the documentation or other materials provided with the distribution
        !            11:  * and in all advertising materials mentioning features or use of this
        !            12:  * software. Neither the name of the University nor the names of its
        !            13:  * contributors may be used to endorse or promote products derived
        !            14:  * from this software without specific prior written permission.
        !            15:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            16:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            17:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            18:  */
        !            19: 
        !            20: #ifndef lint
        !            21: static char sccsid[] = "@(#)hertz.c    5.4 (Berkeley) 6/1/90";
        !            22: #endif /* not lint */
        !            23: 
        !            24: #include <sys/time.h>
        !            25: 
        !            26:     /*
        !            27:      * discover the tick frequency of the machine
        !            28:      * if something goes wrong, we return 0, an impossible hertz.
        !            29:      */
        !            30: #define        HZ_WRONG        0
        !            31: 
        !            32: hertz()
        !            33: {
        !            34:        struct itimerval tim;
        !            35: 
        !            36:        tim.it_interval.tv_sec = 0;
        !            37:        tim.it_interval.tv_usec = 1;
        !            38:        tim.it_value.tv_sec = 0;
        !            39:        tim.it_value.tv_usec = 0;
        !            40:        setitimer(ITIMER_REAL, &tim, 0);
        !            41:        setitimer(ITIMER_REAL, 0, &tim);
        !            42:        if (tim.it_interval.tv_usec < 2)
        !            43:                return(HZ_WRONG);
        !            44:        return (1000000 / tim.it_interval.tv_usec);
        !            45: }

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