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b8f253e8 | 1 | /* |
dc51c380 KB |
2 | * Copyright (c) 1989 The Regents of the University of California. |
3 | * All rights reserved. | |
4 | * | |
269a7923 | 5 | * %sccs.include.redist.c% |
b8f253e8 KM |
6 | */ |
7 | ||
2ce81398 | 8 | #if defined(LIBC_SCCS) && !defined(lint) |
c5980113 | 9 | static char sccsid[] = "@(#)usleep.c 5.6 (Berkeley) %G%"; |
dc51c380 | 10 | #endif /* LIBC_SCCS and not lint */ |
c75c7775 S |
11 | |
12 | #include <sys/time.h> | |
dc51c380 | 13 | #include <sys/signal.h> |
c5980113 | 14 | #include <unistd.h> |
c75c7775 | 15 | |
dc51c380 KB |
16 | #define TICK 10000 /* system clock resolution in microseconds */ |
17 | #define USPS 1000000 /* number of microseconds in a second */ | |
c75c7775 S |
18 | |
19 | #define setvec(vec, a) \ | |
20 | vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0 | |
21 | ||
22 | static int ringring; | |
23 | ||
c5980113 | 24 | void |
dc51c380 KB |
25 | usleep(useconds) |
26 | unsigned int useconds; | |
c75c7775 | 27 | { |
dc51c380 | 28 | register struct itimerval *itp; |
c75c7775 | 29 | struct itimerval itv, oitv; |
c75c7775 | 30 | struct sigvec vec, ovec; |
dc51c380 | 31 | long omask; |
c5980113 | 32 | static void sleephandler(); |
c75c7775 | 33 | |
dc51c380 KB |
34 | itp = &itv; |
35 | if (!useconds) | |
c75c7775 S |
36 | return; |
37 | timerclear(&itp->it_interval); | |
38 | timerclear(&itp->it_value); | |
39 | if (setitimer(ITIMER_REAL, itp, &oitv) < 0) | |
40 | return; | |
dc51c380 KB |
41 | itp->it_value.tv_sec = useconds / USPS; |
42 | itp->it_value.tv_usec = useconds % USPS; | |
c75c7775 S |
43 | if (timerisset(&oitv.it_value)) { |
44 | if (timercmp(&oitv.it_value, &itp->it_value, >)) { | |
45 | oitv.it_value.tv_sec -= itp->it_value.tv_sec; | |
46 | oitv.it_value.tv_usec -= itp->it_value.tv_usec; | |
47 | if (oitv.it_value.tv_usec < 0) { | |
48 | oitv.it_value.tv_usec += USPS; | |
49 | oitv.it_value.tv_sec--; | |
50 | } | |
51 | } else { | |
52 | itp->it_value = oitv.it_value; | |
53 | oitv.it_value.tv_sec = 0; | |
54 | oitv.it_value.tv_usec = 2 * TICK; | |
55 | } | |
56 | } | |
dc51c380 | 57 | setvec(vec, sleephandler); |
c75c7775 S |
58 | (void) sigvec(SIGALRM, &vec, &ovec); |
59 | omask = sigblock(sigmask(SIGALRM)); | |
60 | ringring = 0; | |
61 | (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0); | |
62 | while (!ringring) | |
63 | sigpause(omask &~ sigmask(SIGALRM)); | |
64 | (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0); | |
65 | (void) sigsetmask(omask); | |
66 | (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0); | |
67 | } | |
68 | ||
dc51c380 KB |
69 | static void |
70 | sleephandler() | |
c75c7775 | 71 | { |
c75c7775 S |
72 | ringring = 1; |
73 | } |