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 #include <unistd.h>
13 #include <sys/time.h>
14 #include <signal.h>
15
16 #define USPS 1000000 /* number of microseconds in a second */
17 #define TICK (USPS / _sysconf(_SC_CLK_TCK))
18
19 #define setvec(vec, a) \
20 vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0
21
22 static int ringring;
23
24 static void
sleepx(void)25 sleepx(void)
26 {
27
28 ringring = 1;
29 }
30
31 void
usleep(unsigned n)32 usleep(unsigned n)
33 {
34 int omask;
35 struct itimerval itv, oitv;
36 struct itimerval *itp = &itv;
37 struct sigvec vec, ovec;
38
39 if (n == 0)
40 return;
41 timerclear(&itp->it_interval);
42 timerclear(&itp->it_value);
43 if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
44 return;
45 itp->it_value.tv_sec = n / USPS;
46 itp->it_value.tv_usec = n % USPS;
47 if (timerisset(&oitv.it_value)) {
48 if (timercmp(&oitv.it_value, &itp->it_value, >)) {
49 oitv.it_value.tv_sec -= itp->it_value.tv_sec;
50 oitv.it_value.tv_usec -= itp->it_value.tv_usec;
51 if (oitv.it_value.tv_usec < 0) {
52 oitv.it_value.tv_usec += USPS;
53 oitv.it_value.tv_sec--;
54 }
55 } else {
56 itp->it_value = oitv.it_value;
57 oitv.it_value.tv_sec = 0;
58 oitv.it_value.tv_usec = 2 * TICK;
59 }
60 }
61 setvec(vec, sleepx);
62 (void) sigvec(SIGALRM, &vec, &ovec);
63 omask = sigblock(sigmask(SIGALRM));
64 ringring = 0;
65 (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0);
66 while (!ringring)
67 sigpause(omask &~ sigmask(SIGALRM));
68 (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
69 (void) sigsetmask(omask);
70 (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0);
71 }
72