source: downloads/tcl8.5.2/unix/tclUnixEvent.c @ 42

/*
 * tclUnixEvent.c --
 *
 *      This file implements Unix specific event related routines.
 *
 * Copyright (c) 1997 by Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclUnixEvent.c,v 1.9 2005/11/02 23:26:50 dkf Exp $
 */

#include "tclInt.h"

/*
 *----------------------------------------------------------------------
 *
 * Tcl_Sleep --
 *
 *      Delay execution for the specified number of milliseconds.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Time passes.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_Sleep(
    int ms)                     /* Number of milliseconds to sleep. */
{
    struct timeval delay;
    Tcl_Time before, after, vdelay;

    /*
     * The only trick here is that select appears to return early under some
     * conditions, so we have to check to make sure that the right amount of
     * time really has elapsed.  If it's too early, go back to sleep again.
     */

    Tcl_GetTime(&before);
    after = before;
    after.sec += ms/1000;
    after.usec += (ms%1000)*1000;
    if (after.usec > 1000000) {
        after.usec -= 1000000;
        after.sec += 1;
    }
    while (1) {
        /*
         * TIP #233: Scale from virtual time to real-time for select.
         */

        vdelay.sec  = after.sec  - before.sec;
        vdelay.usec = after.usec - before.usec;

        if (vdelay.usec < 0) {
            vdelay.usec += 1000000;
            vdelay.sec  -= 1;
        }

        if ((vdelay.sec != 0) || (vdelay.usec != 0)) {
            (*tclScaleTimeProcPtr) (&vdelay, tclTimeClientData);
        }

        delay.tv_sec  = vdelay.sec;
        delay.tv_usec = vdelay.usec;

        /*
         * Special note: must convert delay.tv_sec to int before comparing to
         * zero, since delay.tv_usec is unsigned on some platforms.
         */

        if ((((int) delay.tv_sec) < 0)
                || ((delay.tv_usec == 0) && (delay.tv_sec == 0))) {
            break;
        }
        (void) select(0, (SELECT_MASK *) 0, (SELECT_MASK *) 0,
                (SELECT_MASK *) 0, &delay);
        Tcl_GetTime(&before);
    }
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */