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15637ed4 RG |
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, with or without | |
6 | * modification, are permitted provided that the following conditions | |
7 | * are met: | |
8 | * 1. Redistributions of source code must retain the above copyright | |
9 | * notice, this list of conditions and the following disclaimer. | |
10 | * 2. Redistributions in binary form must reproduce the above copyright | |
11 | * notice, this list of conditions and the following disclaimer in the | |
12 | * documentation and/or other materials provided with the distribution. | |
13 | * 3. All advertising materials mentioning features or use of this software | |
14 | * must display the following acknowledgement: | |
15 | * This product includes software developed by the University of | |
16 | * California, Berkeley and its contributors. | |
17 | * 4. Neither the name of the University nor the names of its contributors | |
18 | * may be used to endorse or promote products derived from this software | |
19 | * without specific prior written permission. | |
20 | * | |
21 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
22 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
25 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
26 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
27 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
28 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
30 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
31 | * SUCH DAMAGE. | |
32 | */ | |
33 | ||
34 | #if defined(LIBC_SCCS) && !defined(lint) | |
35 | static char sccsid[] = "@(#)usleep.c 5.6 (Berkeley) 2/23/91"; | |
36 | #endif /* LIBC_SCCS and not lint */ | |
37 | ||
38 | #include <sys/time.h> | |
39 | #include <sys/signal.h> | |
40 | #include <unistd.h> | |
41 | ||
42 | #define TICK 10000 /* system clock resolution in microseconds */ | |
43 | #define USPS 1000000 /* number of microseconds in a second */ | |
44 | ||
45 | #define setvec(vec, a) \ | |
46 | vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0 | |
47 | ||
48 | static int ringring; | |
49 | ||
50 | void | |
51 | usleep(useconds) | |
52 | unsigned int useconds; | |
53 | { | |
54 | register struct itimerval *itp; | |
55 | struct itimerval itv, oitv; | |
56 | struct sigvec vec, ovec; | |
57 | long omask; | |
58 | static void sleephandler(); | |
59 | ||
60 | itp = &itv; | |
61 | if (!useconds) | |
62 | return; | |
63 | timerclear(&itp->it_interval); | |
64 | timerclear(&itp->it_value); | |
65 | if (setitimer(ITIMER_REAL, itp, &oitv) < 0) | |
66 | return; | |
67 | itp->it_value.tv_sec = useconds / USPS; | |
68 | itp->it_value.tv_usec = useconds % USPS; | |
69 | if (timerisset(&oitv.it_value)) { | |
70 | if (timercmp(&oitv.it_value, &itp->it_value, >)) { | |
71 | oitv.it_value.tv_sec -= itp->it_value.tv_sec; | |
72 | oitv.it_value.tv_usec -= itp->it_value.tv_usec; | |
73 | if (oitv.it_value.tv_usec < 0) { | |
74 | oitv.it_value.tv_usec += USPS; | |
75 | oitv.it_value.tv_sec--; | |
76 | } | |
77 | } else { | |
78 | itp->it_value = oitv.it_value; | |
79 | oitv.it_value.tv_sec = 0; | |
80 | oitv.it_value.tv_usec = 2 * TICK; | |
81 | } | |
82 | } | |
83 | setvec(vec, sleephandler); | |
84 | (void) sigvec(SIGALRM, &vec, &ovec); | |
85 | omask = sigblock(sigmask(SIGALRM)); | |
86 | ringring = 0; | |
87 | (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0); | |
88 | while (!ringring) | |
89 | sigpause(omask &~ sigmask(SIGALRM)); | |
90 | (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0); | |
91 | (void) sigsetmask(omask); | |
92 | (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0); | |
93 | } | |
94 | ||
95 | static void | |
96 | sleephandler() | |
97 | { | |
98 | ringring = 1; | |
99 | } |