1 // fg_timer.cxx -- time handling routines
3 // Written by Curtis Olson, started June 1997.
5 // Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
28 #include <signal.h> // for timer routines
29 #include <stdio.h> // for printf()
35 #ifdef HAVE_SYS_TIME_H
36 # include <sys/time.h> // for get/setitimer, gettimeofday, struct timeval
39 #include "fg_timer.hxx"
40 #include "timestamp.hxx"
43 unsigned long int fgSimTime;
46 static struct itimerval t, ot;
47 static void (*callbackfunc)(int multi_loop);
50 // This routine catches the SIGALRM
51 void fgTimerCatch( int dummy ) {
54 // get past a compiler warning
55 warning_avoider = dummy;
57 // ignore any SIGALRM's until we come back from our EOM iteration
58 signal(SIGALRM, SIG_IGN);
60 // printf("In fgTimerCatch()\n");
62 // -1 tells the routine to use default interval rather than
63 // something dynamically calculated based on frame rate
66 signal(SIGALRM, fgTimerCatch);
70 // this routine initializes the interval timer to generate a SIGALRM
71 // after the specified interval (dt)
72 void fgTimerInit(float dt, void (*f)( int )) {
80 usec = 1000000 * ((int)dt - isec);
82 t.it_interval.tv_sec = isec;
83 t.it_interval.tv_usec = usec;
84 t.it_value.tv_sec = isec;
85 t.it_value.tv_usec = usec;
86 // printf("fgTimerInit() called\n");
87 fgTimerCatch(0); // set up for SIGALRM signal catch
88 terr = setitimer( ITIMER_REAL, &t, &ot );
90 printf("Error returned from setitimer");
94 #endif // HAVE_SETITIMER
97 // This function returns the number of microseconds since the last
98 // time it was called.
99 int fgGetTimeInterval( void ) {
101 static int inited = 0;
102 static FGTimeStamp last;
112 interval = current - last;