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3d6c6501 SEF |
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 | ||
c06e55d9 KR |
32 | #ifdef __MSDOS__ |
33 | #define HERTZ 18 | |
34 | #endif | |
35 | ||
3d6c6501 SEF |
36 | hertz() |
37 | { | |
c06e55d9 KR |
38 | #ifdef HERTZ |
39 | return HERTZ; | |
40 | #else | |
3d6c6501 SEF |
41 | struct itimerval tim; |
42 | ||
43 | tim.it_interval.tv_sec = 0; | |
44 | tim.it_interval.tv_usec = 1; | |
45 | tim.it_value.tv_sec = 0; | |
46 | tim.it_value.tv_usec = 0; | |
47 | setitimer(ITIMER_REAL, &tim, 0); | |
48 | setitimer(ITIMER_REAL, 0, &tim); | |
49 | if (tim.it_interval.tv_usec < 2) | |
50 | return(HZ_WRONG); | |
51 | return (1000000 / tim.it_interval.tv_usec); | |
c06e55d9 | 52 | #endif |
3d6c6501 | 53 | } |