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Annotation of 43BSDReno/lib/libc/gen/usleep.c, revision 1.1.1.1

1.1       root        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 are permitted
                      6:  * provided that: (1) source distributions retain this entire copyright
                      7:  * notice and comment, and (2) distributions including binaries display
                      8:  * the following acknowledgement:  ``This product includes software
                      9:  * developed by the University of California, Berkeley and its contributors''
                     10:  * in the documentation or other materials provided with the distribution
                     11:  * and in all advertising materials mentioning features or use of this
                     12:  * software. Neither the name of the University nor the names of its
                     13:  * contributors may be used to endorse or promote products derived
                     14:  * from this software without specific prior written permission.
                     15:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
                     16:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
                     17:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     18:  */
                     19: 
                     20: #if defined(LIBC_SCCS) && !defined(lint)
                     21: static char sccsid[] = "@(#)usleep.c   5.5 (Berkeley) 6/1/90";
                     22: #endif /* LIBC_SCCS and not lint */
                     23: 
                     24: #include <sys/time.h>
                     25: #include <sys/signal.h>
                     26: 
                     27: #define        TICK    10000           /* system clock resolution in microseconds */
                     28: #define        USPS    1000000         /* number of microseconds in a second */
                     29: 
                     30: #define        setvec(vec, a) \
                     31:        vec.sv_handler = a; vec.sv_mask = vec.sv_onstack = 0
                     32: 
                     33: static int ringring;
                     34: 
                     35: usleep(useconds)
                     36:        unsigned int useconds;
                     37: {
                     38:        register struct itimerval *itp;
                     39:        struct itimerval itv, oitv;
                     40:        struct sigvec vec, ovec;
                     41:        long omask;
                     42:        void sleephandler();
                     43: 
                     44:        itp = &itv;
                     45:        if (!useconds)
                     46:                return;
                     47:        timerclear(&itp->it_interval);
                     48:        timerclear(&itp->it_value);
                     49:        if (setitimer(ITIMER_REAL, itp, &oitv) < 0)
                     50:                return;
                     51:        itp->it_value.tv_sec = useconds / USPS;
                     52:        itp->it_value.tv_usec = useconds % USPS;
                     53:        if (timerisset(&oitv.it_value)) {
                     54:                if (timercmp(&oitv.it_value, &itp->it_value, >)) {
                     55:                        oitv.it_value.tv_sec -= itp->it_value.tv_sec;
                     56:                        oitv.it_value.tv_usec -= itp->it_value.tv_usec;
                     57:                        if (oitv.it_value.tv_usec < 0) {
                     58:                                oitv.it_value.tv_usec += USPS;
                     59:                                oitv.it_value.tv_sec--;
                     60:                        }
                     61:                } else {
                     62:                        itp->it_value = oitv.it_value;
                     63:                        oitv.it_value.tv_sec = 0;
                     64:                        oitv.it_value.tv_usec = 2 * TICK;
                     65:                }
                     66:        }
                     67:        setvec(vec, sleephandler);
                     68:        (void) sigvec(SIGALRM, &vec, &ovec);
                     69:        omask = sigblock(sigmask(SIGALRM));
                     70:        ringring = 0;
                     71:        (void) setitimer(ITIMER_REAL, itp, (struct itimerval *)0);
                     72:        while (!ringring)
                     73:                sigpause(omask &~ sigmask(SIGALRM));
                     74:        (void) sigvec(SIGALRM, &ovec, (struct sigvec *)0);
                     75:        (void) sigsetmask(omask);
                     76:        (void) setitimer(ITIMER_REAL, &oitv, (struct itimerval *)0);
                     77: }
                     78: 
                     79: static void
                     80: sleephandler()
                     81: {
                     82:        ringring = 1;
                     83: }

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