1 /**************************************************************************
2 * fg_timer.c -- time handling routines
4 * Written by Curtis Olson, started June 1997.
6 * Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of the
11 * License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 * (Log is kept at end of this file)
24 **************************************************************************/
27 #include <signal.h> /* for timer routines */
28 #include <stdio.h> /* for printf() */
29 #include <sys/time.h> /* for get/setitimer, gettimeofday, struct timeval */
36 unsigned long int fgSimTime;
39 static struct itimerval t, ot;
40 static void (*callbackfunc)(int multi_loop);
43 /* This routine catches the SIGALRM */
45 /* ignore any SIGALRM's until we come back from our EOM iteration */
46 signal(SIGALRM, SIG_IGN);
48 /* printf("In fgTimerCatch()\n"); */
50 /* -1 tells the routine to use default interval rather than something
51 dynamically calculated based on frame rate */
54 signal(SIGALRM, fgTimerCatch);
58 /* this routine initializes the interval timer to generate a SIGALRM after
59 * the specified interval (dt) */
60 void fgTimerInit(float dt, void (*f)()) {
68 usec = 1000000* (dt - (float) isec);
70 t.it_interval.tv_sec = isec;
71 t.it_interval.tv_usec = usec;
72 t.it_value.tv_sec = isec;
73 t.it_value.tv_usec = usec;
74 /* printf("fgTimerInit() called\n"); */
75 fgTimerCatch(); /* set up for SIGALRM signal catch */
76 terr = setitimer( ITIMER_REAL, &t, &ot );
78 printf("Error returned from setitimer");
85 /* This function returns the number of milleseconds since the last
86 time it was called. */
87 int fgGetTimeInterval() {
88 static struct timeval last;
89 static struct timeval current;
90 static struct timezone tz;
91 static int inited = 0;
97 gettimeofday(&last, &tz);
100 gettimeofday(¤t, &tz);
101 interval = 1000000 * (current.tv_sec - last.tv_sec) +
102 (current.tv_usec - last.tv_usec);
103 interval /= 1000; /* convert back to milleseconds */
112 /* Revision 1.4 1997/06/25 15:39:49 curt
113 /* Minor changes to compile with rsxnt/win32.
115 * Revision 1.3 1997/06/17 16:52:04 curt
116 * Timer interval stuff now uses gettimeofday() instead of ftime()
118 * Revision 1.2 1997/06/17 03:41:10 curt
119 * Nonsignal based interval timing is now working.
120 * This would be a good time to look at cleaning up the code structure a bit.
122 * Revision 1.1 1997/06/16 19:24:20 curt