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Annotation of 43BSDTahoe/ucb/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 the above copyright notice and this paragraph are
                      7:  * duplicated in all such forms and that any documentation,
                      8:  * advertising materials, and other materials related to such
                      9:  * distribution and use acknowledge that the software was developed
                     10:  * by the University of California, Berkeley.  The name of the
                     11:  * University may not be used to endorse or promote products derived
                     12:  * from this software without specific prior written permission.
                     13:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
                     14:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
                     15:  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     16:  */
                     17: 
                     18: #ifndef lint
                     19: static char sccsid[] = "@(#)hertz.c    5.3 (Berkeley) 6/29/88";
                     20: #endif /* not lint */
                     21: 
                     22: #include <sys/time.h>
                     23: 
                     24:     /*
                     25:      * discover the tick frequency of the machine
                     26:      * if something goes wrong, we return 0, an impossible hertz.
                     27:      */
                     28: #define        HZ_WRONG        0
                     29: 
                     30: hertz()
                     31: {
                     32:        struct itimerval tim;
                     33: 
                     34:        tim.it_interval.tv_sec = 0;
                     35:        tim.it_interval.tv_usec = 1;
                     36:        tim.it_value.tv_sec = 0;
                     37:        tim.it_value.tv_usec = 0;
                     38:        setitimer(ITIMER_REAL, &tim, 0);
                     39:        setitimer(ITIMER_REAL, 0, &tim);
                     40:        if (tim.it_interval.tv_usec < 2)
                     41:                return(HZ_WRONG);
                     42:        return (1000000 / tim.it_interval.tv_usec);
                     43: }

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