xref: /csrg-svn/lib/libc/gen/clock.c (revision 42195)
1 /*
2  * Copyright (c) 1989 The 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 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
16  */
17 
18 #if defined(LIBC_SCCS) && !defined(lint)
19 static char sccsid[] = "@(#)clock.c	5.2 (Berkeley) 05/17/90";
20 #endif /* LIBC_SCCS and not lint */
21 
22 #include <machine/machlimits.h>
23 #include <sys/types.h>
24 #include <sys/time.h>
25 #include <sys/resource.h>
26 
27 clock_t
28 clock()
29 {
30 	struct rusage rusage;
31 	clock_t val;
32 
33 	if (getrusage(RUSAGE_SELF, &rusage))
34 		return ((clock_t) -1);
35 	val = (rusage.ru_utime.tv_sec + rusage.ru_stime.tv_sec) * CLK_TCK;
36 	/*
37 	 * Convert usec to clock ticks; could do (usec * CLK_TCK) / 1000000,
38 	 * but this would overflow if we switch to nanosec.
39 	 */
40 	val += (rusage.ru_utime.tv_usec + rusage.ru_stime.tv_usec) /
41 		(1000000 / CLK_TCK);
42 	return (val);
43 }
44