From:	lawrencej AT ufrsd DOT k12 DOT nj DOT us
Newsgroups:	comp.os.msdos.djgpp
Subject:	Game speed timer a little jerky
Date:	Sat, 02 Jan 1999 22:02:06 GMT
Organization:	Deja News - The Leader in Internet Discussion
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

 I'm using the game timer featured in George Foot's Allegro Vivace...


     volatile int target_cycle;

     void target_incrementor()
     {
         target_cycle++;
     }
     END_OF_FUNCTION (target_incrementor);

     int actual_cycle;
     int end_game;

     void game_loop()
     {
         LOCK_VARIABLE (target_cycle);
         LOCK_FUNCTION (target_incrementor);
         install_int_ex (target_incrementor, BPS_TO_TIMER (cycles_per_sec));
         end_game = 0;
         actual_cycle = target_cycle = 0;
         do {
             draw_one_frame();
             while (target_cycle > actual_cycle)
                 do_one_game_cycle();
         } while (!end_game);
     }

 I'm using a double buffer (and vsync) in mode 13h and my cycles_per_sec is
set at 30.  The program runs pretty smooth, but at what seems like regular
intervals of about 1-2 sec, it slightly jerks.	I'm not blasting a lotta
graphics, or number crunching, so I believe the problem has to do with the
cycles_per_sec value. (I am throwing around a pointer to a 320x200x256 bitmap
a lot in my code, but that shouldn't affect it.)  Any help?

-- JL

PS - I can e-mail the proggy to anyone, but not post it here since it's big.

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