125 lines
4.4 KiB
C
125 lines
4.4 KiB
C
/*
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SDL - Simple DirectMedia Layer
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Copyright (C) 1997-2009 Sam Lantinga
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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Sam Lantinga
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slouken@libsdl.org
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*/
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#ifndef _SDL_timer_h
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#define _SDL_timer_h
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/** @file SDL_timer.h
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* Header for the SDL time management routines
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*/
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#include "SDL_stdinc.h"
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#include "SDL_error.h"
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#include "begin_code.h"
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/* Set up for C function definitions, even when using C++ */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** This is the OS scheduler timeslice, in milliseconds */
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#define SDL_TIMESLICE 10
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/** This is the maximum resolution of the SDL timer on all platforms */
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#define TIMER_RESOLUTION 10 /**< Experimentally determined */
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/**
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* Get the number of milliseconds since the SDL library initialization.
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* Note that this value wraps if the program runs for more than ~49 days.
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*/
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extern DECLSPEC Uint32 SDLCALL SDL_GetTicks(void);
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/** Wait a specified number of milliseconds before returning */
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extern DECLSPEC void SDLCALL SDL_Delay(Uint32 ms);
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/** Function prototype for the timer callback function */
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typedef Uint32 (SDLCALL *SDL_TimerCallback)(Uint32 interval);
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/**
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* Set a callback to run after the specified number of milliseconds has
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* elapsed. The callback function is passed the current timer interval
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* and returns the next timer interval. If the returned value is the
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* same as the one passed in, the periodic alarm continues, otherwise a
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* new alarm is scheduled. If the callback returns 0, the periodic alarm
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* is cancelled.
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*
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* To cancel a currently running timer, call SDL_SetTimer(0, NULL);
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*
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* The timer callback function may run in a different thread than your
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* main code, and so shouldn't call any functions from within itself.
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*
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* The maximum resolution of this timer is 10 ms, which means that if
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* you request a 16 ms timer, your callback will run approximately 20 ms
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* later on an unloaded system. If you wanted to set a flag signaling
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* a frame update at 30 frames per second (every 33 ms), you might set a
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* timer for 30 ms:
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* @code SDL_SetTimer((33/10)*10, flag_update); @endcode
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*
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* If you use this function, you need to pass SDL_INIT_TIMER to SDL_Init().
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*
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* Under UNIX, you should not use raise or use SIGALRM and this function
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* in the same program, as it is implemented using setitimer(). You also
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* should not use this function in multi-threaded applications as signals
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* to multi-threaded apps have undefined behavior in some implementations.
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*
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* This function returns 0 if successful, or -1 if there was an error.
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*/
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extern DECLSPEC int SDLCALL SDL_SetTimer(Uint32 interval, SDL_TimerCallback callback);
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/** @name New timer API
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* New timer API, supports multiple timers
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* Written by Stephane Peter <megastep@lokigames.com>
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*/
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/*@{*/
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/**
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* Function prototype for the new timer callback function.
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* The callback function is passed the current timer interval and returns
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* the next timer interval. If the returned value is the same as the one
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* passed in, the periodic alarm continues, otherwise a new alarm is
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* scheduled. If the callback returns 0, the periodic alarm is cancelled.
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*/
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typedef Uint32 (SDLCALL *SDL_NewTimerCallback)(Uint32 interval, void *param);
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/** Definition of the timer ID type */
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typedef struct _SDL_TimerID *SDL_TimerID;
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/** Add a new timer to the pool of timers already running.
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* Returns a timer ID, or NULL when an error occurs.
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*/
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extern DECLSPEC SDL_TimerID SDLCALL SDL_AddTimer(Uint32 interval, SDL_NewTimerCallback callback, void *param);
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/**
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* Remove one of the multiple timers knowing its ID.
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* Returns a boolean value indicating success.
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*/
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extern DECLSPEC SDL_bool SDLCALL SDL_RemoveTimer(SDL_TimerID t);
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/*@}*/
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/* Ends C function definitions when using C++ */
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#ifdef __cplusplus
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}
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#endif
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#include "close_code.h"
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#endif /* _SDL_timer_h */
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