119 lines
2.8 KiB
C++
119 lines
2.8 KiB
C++
// fg_timer.cxx -- 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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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <signal.h> // for timer routines
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#include <stdio.h> // for printf()
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#ifdef HAVE_STDLIB_H
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# include <stdlib.h>
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#endif
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#ifdef HAVE_SYS_TIME_H
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# include <sys/time.h> // for get/setitimer, gettimeofday, struct timeval
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#endif
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#include "fg_time.hxx"
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#include "fg_timer.hxx"
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#include "timestamp.hxx"
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unsigned long int fgSimTime;
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#ifdef HAVE_SETITIMER
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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( int dummy ) {
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int warning_avoider;
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// get past a compiler warning
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warning_avoider = dummy;
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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
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// something 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
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// after the specified interval (dt)
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void fgTimerInit(float dt, void (*f)( int )) {
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int terr;
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int isec;
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int usec;
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callbackfunc = f;
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isec = (int) dt;
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usec = 1000000 * ((int)dt - 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(0); // 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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#endif // HAVE_SETITIMER
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// This function returns the number of microseconds since the last
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// time it was called.
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int fgGetTimeInterval( void ) {
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int interval;
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static int inited = 0;
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static FGTimeStamp last;
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FGTimeStamp current;
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if ( ! inited ) {
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inited = 1;
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last.stamp();
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interval = 0;
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} else {
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current.stamp();
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interval = current - last;
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last = current;
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}
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return(interval);
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}
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