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/*
t4k_throttle.c:
A simple function that uses SDL_Delay() to keep loops from eating
all available CPU.
Copyright 2009, 2010.
Author: David Bruce
Project email: <tuxmath-devel@lists.sourceforge.net>
Project website: http://tux4kids.alioth.debian.org
throttle.c is part of "Tux, of Math Command", a.k.a. "tuxmath".
Tuxmath 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 3 of the License, or
(at your option) any later version.
Tuxmath 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, see <http://www.gnu.org/licenses/>.
*/
#include "t4k_globals.h"
#include "SDL.h"
/* NOTE now store the time elsewhere to make function thread-safe */
void T4K_Throttle(int loop_msec, Uint32* last_t)
{
Uint32 now_t, wait_t;
if(!last_t)
return;
//Target loop time must be between 0 and 1000 msec:
if(loop_msec < 0)
loop_msec = 0;
if(loop_msec > 1000)
loop_msec = 1000;
//See if we need to wait:
now_t = SDL_GetTicks();
if (now_t < (*last_t + loop_msec))
{
wait_t = (*last_t + loop_msec) - now_t;
//Avoid problem if we somehow wrap past uint32 size (at 49.7 days!)
if(wait_t < 0)
wait_t = 0;
if(wait_t > loop_msec)
wait_t = loop_msec;
SDL_Delay(wait_t);
}
*last_t = SDL_GetTicks();
}
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