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Annotation of 43BSDReno/pgrm/gprof/hertz.c, revision 1.1.1.1

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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