// fg_timer.cxx -- time handling routines
//
// Written by Curtis Olson, started June 1997.
//
// Copyright (C) 1997  Curtis L. Olson  - curt@infoplane.com
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// $Id$
// (Log is kept at end of this file)


#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <signal.h>    // for timer routines
#include <stdio.h>     // for printf()

#ifdef HAVE_STDLIB_H
#  include <stdlib.h>
#endif

#ifdef HAVE_SYS_TIME_H
#  include <sys/time.h>  // for get/setitimer, gettimeofday, struct timeval
#endif

#include "fg_time.hxx"
#include "fg_timer.hxx"
#include "timestamp.hxx"


unsigned long int fgSimTime;

#ifdef HAVE_SETITIMER
  static struct itimerval t, ot;
  static void (*callbackfunc)(int multi_loop);


// This routine catches the SIGALRM
void fgTimerCatch( int dummy ) {
    int warning_avoider;

    // get past a compiler warning
    warning_avoider = dummy;

    // ignore any SIGALRM's until we come back from our EOM iteration
    signal(SIGALRM, SIG_IGN);

    // printf("In fgTimerCatch()\n");

    // -1 tells the routine to use default interval rather than
    // something dynamically calculated based on frame rate
    callbackfunc(-1); 

    signal(SIGALRM, fgTimerCatch);
}


// this routine initializes the interval timer to generate a SIGALRM
// after the specified interval (dt)
void fgTimerInit(float dt, void (*f)( int )) {
    int terr;
    int isec;
    int usec;

    callbackfunc = f;

    isec = (int) dt;
    usec = 1000000 * ((int)dt - isec);

    t.it_interval.tv_sec = isec;
    t.it_interval.tv_usec = usec;
    t.it_value.tv_sec = isec;
    t.it_value.tv_usec = usec;
    // printf("fgTimerInit() called\n");
    fgTimerCatch(0);   // set up for SIGALRM signal catch
    terr = setitimer( ITIMER_REAL, &t, &ot );
    if (terr) {
	printf("Error returned from setitimer");
	exit(0);
    }
}
#endif // HAVE_SETITIMER


// This function returns the number of microseconds since the last
// time it was called.
int fgGetTimeInterval( void ) {
    int interval;
    static int inited = 0;
    static FGTimeStamp last;
    FGTimeStamp current;

    if ( ! inited ) {
	inited = 1;
	last.stamp();
	interval = 0;
    } else {
        current.stamp();
	interval = current - last;
	last = current;
    }

    return(interval);
}


// $Log$
// Revision 1.6  1999/01/09 13:37:45  curt
// Convert fgTIMESTAMP to FGTimeStamp which holds usec instead of ms.
//
// Revision 1.5  1998/12/05 14:21:32  curt
// Moved struct fg_timestamp to class fgTIMESTAMP and moved it's definition
// to it's own file, timestamp.hxx.
//
// Revision 1.4  1998/12/04 01:32:51  curt
// Converted "struct fg_timestamp" to "class fgTIMESTAMP" and added some
// convenience inline operators.
//
// Revision 1.3  1998/04/28 01:22:18  curt
// Type-ified fgTIME and fgVIEW.
//
// Revision 1.2  1998/04/25 20:24:03  curt
// Cleaned up initialization sequence to eliminate interdependencies
// between sun position, lighting, and view position.  This creates a
// valid single pass initialization path.
//
// Revision 1.1  1998/04/24 00:52:29  curt
// Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
// Fog color fixes.
// Separated out lighting calcs into their own file.
//
// Revision 1.12  1998/04/21 17:01:44  curt
// Fixed a problems where a pointer to a function was being passed around.  In
// one place this functions arguments were defined as ( void ) while in another
// place they were defined as ( int ).  The correct answer was ( int ).
//
// Prepairing for C++ integration.
//
// Revision 1.11  1998/04/03 22:12:56  curt
// Converting to Gnu autoconf system.
// Centralized time handling differences.
//
// Revision 1.10  1998/01/31 00:43:45  curt
// Added MetroWorks patches from Carmen Volpe.
//
// Revision 1.9  1998/01/19 19:27:21  curt
// Merged in make system changes from Bob Kuehne <rpk@sgi.com>
// This should simplify things tremendously.
//
// Revision 1.8  1998/01/19 18:40:39  curt
// Tons of little changes to clean up the code and to remove fatal errors
// when building with the c++ compiler.
//
// Revision 1.7  1997/12/30 13:06:58  curt
// A couple lighting tweaks ...
//
// Revision 1.6  1997/07/12 02:13:04  curt
// Add ftime() support for those that don't have gettimeofday()
//
// Revision 1.5  1997/06/26 19:08:38  curt
// Restructuring make, adding automatic "make dep" support.
//
// Revision 1.4  1997/06/25 15:39:49  curt
// Minor changes to compile with rsxnt/win32.
//
// Revision 1.3  1997/06/17 16:52:04  curt
// Timer interval stuff now uses gettimeofday() instead of ftime()
//
// Revision 1.2  1997/06/17 03:41:10  curt
// Nonsignal based interval timing is now working.
// This would be a good time to look at cleaning up the code structure a bit.
//
// Revision 1.1  1997/06/16 19:24:20  curt
// Initial revision.
//