projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| c0bc4ef7 | 1 | /* |
| 7e9de516 KB |
2 | * Copyright (c) 1983, 1993 |
| 3 | * The Regents of the University of California. All rights reserved. | |
| ddb85eed | 4 | * |
| 6ecf3d85 | 5 | * %sccs.include.redist.c% |
| c0bc4ef7 DF |
6 | */ |
| 7 | ||
| 551f2768 | 8 | #ifndef lint |
| 7e9de516 | 9 | static char sccsid[] = "@(#)hertz.c 8.1 (Berkeley) %G%"; |
| ddb85eed | 10 | #endif /* not lint */ |
| 551f2768 | 11 | |
| 39bd51fe KM |
12 | #include <sys/time.h> |
| 13 | ||
| 551f2768 PK |
14 | /* |
| 15 | * discover the tick frequency of the machine | |
| 648db063 | 16 | * if something goes wrong, we return 0, an impossible hertz. |
| 551f2768 | 17 | */ |
| 648db063 | 18 | #define HZ_WRONG 0 |
| 10ac51bc | 19 | |
| 551f2768 PK |
20 | hertz() |
| 21 | { | |
| 39bd51fe | 22 | struct itimerval tim; |
| 551f2768 | 23 | |
| 39bd51fe KM |
24 | tim.it_interval.tv_sec = 0; |
| 25 | tim.it_interval.tv_usec = 1; | |
| 26 | tim.it_value.tv_sec = 0; | |
| 27 | tim.it_value.tv_usec = 0; | |
| 28 | setitimer(ITIMER_REAL, &tim, 0); | |
| 29 | setitimer(ITIMER_REAL, 0, &tim); | |
| 30 | if (tim.it_interval.tv_usec < 2) | |
| 31 | return(HZ_WRONG); | |
| 32 | return (1000000 / tim.it_interval.tv_usec); | |
| 551f2768 | 33 | } |