usleep.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* Copyright 1996 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/* from UCB 5.1 85/06/05 */
/*
* Copyright (c) 1985 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/
#include <unistd.h>
#include <sys/time.h>
#include <signal.h>
#define USPS 1000000 /* number of microseconds in a second */
#define TICK (USPS / _sysconf(_SC_CLK_TCK))
#define setvec(vec, a) \
vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0
static int ringring;
usleep(n)
unsigned n;
{
static void sleepx();
int omask;
struct itimerval itv, oitv;
register struct itimerval *itp = &itv;
struct sigvec vec, ovec;
if (n == 0)
return;
timerclear(&itp->it_interval);
timerclear(&itp->it_value);
if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
return;
itp->it_value.tv_sec = n / USPS;
itp->it_value.tv_usec = n % USPS;
if (timerisset(&oitv.it_value)) {
if (timercmp(&oitv.it_value, &itp->it_value, >)) {
oitv.it_value.tv_sec -= itp->it_value.tv_sec;
oitv.it_value.tv_usec -= itp->it_value.tv_usec;
if (oitv.it_value.tv_usec < 0) {
oitv.it_value.tv_usec += USPS;
oitv.it_value.tv_sec--;
}
} else {
itp->it_value = oitv.it_value;
oitv.it_value.tv_sec = 0;
oitv.it_value.tv_usec = 2 * TICK;
}
}
setvec(vec, sleepx);
(void) sigvec(SIGALRM, &vec, &ovec);
omask = sigblock(sigmask(SIGALRM));
ringring = 0;
(void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0);
while (!ringring)
sigpause(omask &~ sigmask(SIGALRM));
(void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
(void) sigsetmask(omask);
(void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0);
}
static void
sleepx()
{
ringring = 1;
}