1 /*
2 * Copyright 1996 Sun Microsystems, Inc. All rights reserved.
3 * Use is subject to license terms.
4 */
5
6 /*
7 * Copyright (c) 1985 Regents of the University of California.
8 * All rights reserved. The Berkeley software License Agreement
9 * specifies the terms and conditions for redistribution.
10 */
11
12 #pragma ident "%Z%%M% %I% %E% SMI"
13
14 #include <unistd.h>
15 #include <sys/time.h>
16 #include <signal.h>
17
18 #define USPS 1000000 /* number of microseconds in a second */
19 #define TICK (USPS / _sysconf(_SC_CLK_TCK))
20
21 #define setvec(vec, a) \
22 vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0
23
24 static int ringring;
25
26 void
usleep(unsigned n)27 usleep(unsigned n)
28 {
29 static void sleepx();
30 int omask;
31 struct itimerval itv, oitv;
32 struct itimerval *itp = &itv;
33 struct sigvec vec, ovec;
34
35 if (n == 0)
36 return;
37 timerclear(&itp->it_interval);
38 timerclear(&itp->it_value);
39 if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
40 return;
41 itp->it_value.tv_sec = n / USPS;
42 itp->it_value.tv_usec = n % USPS;
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 }
57 setvec(vec, sleepx);
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
69 static void
sleepx(void)70 sleepx(void)
71 {
72
73 ringring = 1;
74 }
75