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252b5132 RH |
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 | #include "hertz.h" | |
20 | ||
21 | ||
22 | #ifdef __MSDOS__ | |
23 | #define HERTZ 18 | |
24 | #endif | |
25 | ||
26 | int | |
27 | hertz () | |
28 | { | |
29 | #ifdef HERTZ | |
30 | return HERTZ; | |
31 | #else /* ! defined (HERTZ) */ | |
32 | #ifdef HAVE_SETITIMER | |
33 | struct itimerval tim; | |
34 | ||
35 | tim.it_interval.tv_sec = 0; | |
36 | tim.it_interval.tv_usec = 1; | |
37 | tim.it_value.tv_sec = 0; | |
38 | tim.it_value.tv_usec = 0; | |
39 | setitimer (ITIMER_REAL, &tim, 0); | |
40 | setitimer (ITIMER_REAL, 0, &tim); | |
41 | if (tim.it_interval.tv_usec < 2) | |
42 | { | |
43 | return HZ_WRONG; | |
44 | } | |
45 | return 1000000 / tim.it_interval.tv_usec; | |
46 | #else /* ! defined (HAVE_SETITIMER) */ | |
47 | #if defined (HAVE_SYSCONF) && defined (_SC_CLK_TCK) | |
48 | return sysconf (_SC_CLK_TCK); | |
49 | #else /* ! defined (HAVE_SYSCONF) || ! defined (_SC_CLK_TCK) */ | |
50 | return HZ_WRONG; | |
51 | #endif /* ! defined (HAVE_SYSCONF) || ! defined (_SC_CLK_TCK) */ | |
52 | #endif /* ! defined (HAVE_SETITIMER) */ | |
53 | #endif /* ! defined (HERTZ) */ | |
54 | } |