119 lines
3.3 KiB
C
119 lines
3.3 KiB
C
/**************************************************************************
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* fg_timer.c -- time handling routines
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*
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* Written by Curtis Olson, started June 1997.
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*
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* Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id$
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* (Log is kept at end of this file)
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**************************************************************************/
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#include <signal.h> /* for timer routines */
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#include <stdio.h> /* for printf() */
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#include <sys/time.h> /* for get/setitimer, gettimeofday, struct timeval */
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#include <unistd.h>
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#include "fg_timer.h"
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unsigned long int fgSimTime;
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static struct itimerval t, ot;
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static void (*callbackfunc)(int multi_loop);
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/* This routine catches the SIGALRM */
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void fgTimerCatch() {
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/* ignore any SIGALRM's until we come back from our EOM iteration */
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signal(SIGALRM, SIG_IGN);
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/* printf("In fgTimerCatch()\n"); */
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/* -1 tells the routine to use default interval rather than something
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dynamically calculated based on frame rate */
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callbackfunc(-1);
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signal(SIGALRM, fgTimerCatch);
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}
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/* this routine initializes the interval timer to generate a SIGALRM after
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* the specified interval (dt) */
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void fgTimerInit(float dt, void (*f)()) {
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int terr;
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int isec;
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float usec;
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callbackfunc = f;
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isec = (int) dt;
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usec = 1000000* (dt - (float) isec);
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t.it_interval.tv_sec = isec;
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t.it_interval.tv_usec = usec;
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t.it_value.tv_sec = isec;
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t.it_value.tv_usec = usec;
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/* printf("fgTimerInit() called\n"); */
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fgTimerCatch(); /* set up for SIGALRM signal catch */
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terr = setitimer( ITIMER_REAL, &t, &ot );
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if (terr) {
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printf("Error returned from setitimer");
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exit(0);
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}
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}
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/* This function returns the number of milleseconds since the last
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time it was called. */
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int fgGetTimeInterval() {
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static struct timeval last;
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static struct timeval current;
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static struct timezone tz;
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static int inited = 0;
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int interval;
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if ( ! inited ) {
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inited = 1;
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gettimeofday(&last, &tz);
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interval = 0;
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} else {
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gettimeofday(¤t, &tz);
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interval = 1000000 * (current.tv_sec - last.tv_sec) +
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(current.tv_usec - last.tv_usec);
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interval /= 1000; /* convert back to milleseconds */
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last = current;
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}
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return(interval);
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}
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/* $Log$
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/* Revision 1.3 1997/06/17 16:52:04 curt
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/* Timer interval stuff now uses gettimeofday() instead of ftime()
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/*
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* Revision 1.2 1997/06/17 03:41:10 curt
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* Nonsignal based interval timing is now working.
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* This would be a good time to look at cleaning up the code structure a bit.
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*
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* Revision 1.1 1997/06/16 19:24:20 curt
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* Initial revision.
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*
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*/
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