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SDL_timer.h
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SDL_timer.h
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/*
SDL - Simple DirectMedia Layer
Copyright (C) 1997-2006 Sam Lantinga
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Sam Lantinga
slouken@libsdl.org
*/
#ifndef _SDL_timer_h
#define _SDL_timer_h
/* Header for the SDL time management routines */
#include "SDL_stdinc.h"
#include "begin_code.h"
/* Set up for C function definitions, even when using C++ */
#ifdef __cplusplus
extern "C" {
#endif
/* This is the OS scheduler timeslice, in milliseconds */
#define SDL_TIMESLICE 10
/* This is the maximum resolution of the SDL timer on all platforms */
#define TIMER_RESOLUTION 10 /* Experimentally determined */
/* Get the number of milliseconds since the SDL library initialization.
* Note that this value wraps if the program runs for more than ~49 days.
*/
extern DECLSPEC Uint32 SDLCALL SDL_GetTicks(void);
/* Wait a specified number of milliseconds before returning */
extern DECLSPEC void SDLCALL SDL_Delay(Uint32 ms);
/* Function prototype for the timer callback function */
typedef Uint32 (SDLCALL *SDL_TimerCallback)(Uint32 interval);
/* Set a callback to run after the specified number of milliseconds has
* elapsed. The callback function is passed the current timer interval
* and returns the next timer interval. If the returned value is the
* same as the one passed in, the periodic alarm continues, otherwise a
* new alarm is scheduled. If the callback returns 0, the periodic alarm
* is cancelled.
*
* To cancel a currently running timer, call SDL_SetTimer(0, NULL);
*
* The timer callback function may run in a different thread than your
* main code, and so shouldn't call any functions from within itself.
*
* The maximum resolution of this timer is 10 ms, which means that if
* you request a 16 ms timer, your callback will run approximately 20 ms
* later on an unloaded system. If you wanted to set a flag signaling
* a frame update at 30 frames per second (every 33 ms), you might set a
* timer for 30 ms:
* SDL_SetTimer((33/10)*10, flag_update);
*
* If you use this function, you need to pass SDL_INIT_TIMER to SDL_Init().
*
* Under UNIX, you should not use raise or use SIGALRM and this function
* in the same program, as it is implemented using setitimer(). You also
* should not use this function in multi-threaded applications as signals
* to multi-threaded apps have undefined behavior in some implementations.
*
* This function returns 0 if successful, or -1 if there was an error.
*/
extern DECLSPEC int SDLCALL SDL_SetTimer(Uint32 interval, SDL_TimerCallback callback);
/* New timer API, supports multiple timers
* Written by Stephane Peter <megastep@lokigames.com>
*/
/* Function prototype for the new timer callback function.
* The callback function is passed the current timer interval and returns
* the next timer interval. If the returned value is the same as the one
* passed in, the periodic alarm continues, otherwise a new alarm is
* scheduled. If the callback returns 0, the periodic alarm is cancelled.
*/
typedef Uint32 (SDLCALL *SDL_NewTimerCallback)(Uint32 interval, void *param);
/* Definition of the timer ID type */
typedef struct _SDL_TimerID *SDL_TimerID;
/* Add a new timer to the pool of timers already running.
Returns a timer ID, or NULL when an error occurs.
*/
extern DECLSPEC SDL_TimerID SDLCALL SDL_AddTimer(Uint32 interval, SDL_NewTimerCallback callback, void *param);
/* Remove one of the multiple timers knowing its ID.
* Returns a boolean value indicating success.
*/
extern DECLSPEC SDL_bool SDLCALL SDL_RemoveTimer(SDL_TimerID t);
/* Ends C function definitions when using C++ */
#ifdef __cplusplus
}
#endif
#include "close_code.h"
#endif /* _SDL_timer_h */