/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2009 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

/** @file SDL_timer.h

 *  Header for the SDL time management routines

 */

#include "SDL_stdinc.h"

#include "SDL_error.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:

 *   @code SDL_SetTimer((33/10)*10, flag_update); @endcode

 *

 * 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);

/** @name New timer API

 * 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 */