/*

    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

/* *INDENT-OFF* */

extern "C" {

/* *INDENT-ON* */

#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 

 *  \code SDL_SetTimer(0, NULL); \endcode

 *  

 *  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.

 *  

 *  \return 0 if successful, or -1 if there was an error.

 */

extern DECLSPEC int SDLCALL SDL_SetTimer(Uint32 interval,

                                         SDL_TimerCallback callback);

/**

 *  \name Peter timers

 *  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.

 *  \return 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.

 *  \return A boolean value indicating success or failure.

 */

extern DECLSPEC SDL_bool SDLCALL SDL_RemoveTimer(SDL_TimerID t);

/*@}*//*Peter timers*/

/* Ends C function definitions when using C++ */

#ifdef __cplusplus

/* *INDENT-OFF* */

}

/* *INDENT-ON* */

#endif

#include "close_code.h"

#endif /* _SDL_timer_h */

/* vi: set ts=4 sw=4 expandtab: */