macro and text revision (-mdoc version 3)

[unix-history] / usr / src / lib / libc / gen / usleep.c

/*
* Copyright (c) 1989 The Regents of the University of California.
* All rights reserved.
*
* %sccs.include.redist.c%
*/

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)usleep.c    5.6 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <sys/time.h>
#include <sys/signal.h>
#include <unistd.h>

#define TICK    10000           /* system clock resolution in microseconds */
#define USPS    1000000         /* number of microseconds in a second */

#define setvec(vec, a) \
       vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0

static int ringring;

void
usleep(useconds)
       unsigned int useconds;
{
       register struct itimerval *itp;
       struct itimerval itv, oitv;
       struct sigvec vec, ovec;
       long omask;
       static void sleephandler();

       itp = &itv;
       if (!useconds)
               return;
       timerclear(&itp->it_interval);
       timerclear(&itp->it_value);
       if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
               return;
       itp->it_value.tv_sec = useconds / USPS;
       itp->it_value.tv_usec = useconds % 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, sleephandler);
       (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
sleephandler()
{
       ringring = 1;
}