1 /* 2 SDL - Simple DirectMedia Layer 3 Copyright (C) 1997-2012 Sam Lantinga 4 5 This library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 This library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with this library; if not, write to the Free Software 17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 18 19 Sam Lantinga 20 slouken (at) libsdl.org 21 */ 22 23 #ifndef _SDL_timer_h 24 #define _SDL_timer_h 25 26 /** @file SDL_timer.h 27 * Header for the SDL time management routines 28 */ 29 30 #include "SDL_stdinc.h" 31 #include "SDL_error.h" 32 33 #include "begin_code.h" 34 /* Set up for C function definitions, even when using C++ */ 35 #ifdef __cplusplus 36 extern "C" { 37 #endif 38 39 /** This is the OS scheduler timeslice, in milliseconds */ 40 #define SDL_TIMESLICE 10 41 42 /** This is the maximum resolution of the SDL timer on all platforms */ 43 #define TIMER_RESOLUTION 10 /**< Experimentally determined */ 44 45 /** 46 * Get the number of milliseconds since the SDL library initialization. 47 * Note that this value wraps if the program runs for more than ~49 days. 48 */ 49 extern DECLSPEC Uint32 SDLCALL SDL_GetTicks(void); 50 51 /** Wait a specified number of milliseconds before returning */ 52 extern DECLSPEC void SDLCALL SDL_Delay(Uint32 ms); 53 54 /** Function prototype for the timer callback function */ 55 typedef Uint32 (SDLCALL *SDL_TimerCallback)(Uint32 interval); 56 57 /** 58 * Set a callback to run after the specified number of milliseconds has 59 * elapsed. The callback function is passed the current timer interval 60 * and returns the next timer interval. If the returned value is the 61 * same as the one passed in, the periodic alarm continues, otherwise a 62 * new alarm is scheduled. If the callback returns 0, the periodic alarm 63 * is cancelled. 64 * 65 * To cancel a currently running timer, call SDL_SetTimer(0, NULL); 66 * 67 * The timer callback function may run in a different thread than your 68 * main code, and so shouldn't call any functions from within itself. 69 * 70 * The maximum resolution of this timer is 10 ms, which means that if 71 * you request a 16 ms timer, your callback will run approximately 20 ms 72 * later on an unloaded system. If you wanted to set a flag signaling 73 * a frame update at 30 frames per second (every 33 ms), you might set a 74 * timer for 30 ms: 75 * @code SDL_SetTimer((33/10)*10, flag_update); @endcode 76 * 77 * If you use this function, you need to pass SDL_INIT_TIMER to SDL_Init(). 78 * 79 * Under UNIX, you should not use raise or use SIGALRM and this function 80 * in the same program, as it is implemented using setitimer(). You also 81 * should not use this function in multi-threaded applications as signals 82 * to multi-threaded apps have undefined behavior in some implementations. 83 * 84 * This function returns 0 if successful, or -1 if there was an error. 85 */ 86 extern DECLSPEC int SDLCALL SDL_SetTimer(Uint32 interval, SDL_TimerCallback callback); 87 88 /** @name New timer API 89 * New timer API, supports multiple timers 90 * Written by Stephane Peter <megastep (at) lokigames.com> 91 */ 92 /*@{*/ 93 94 /** 95 * Function prototype for the new timer callback function. 96 * The callback function is passed the current timer interval and returns 97 * the next timer interval. If the returned value is the same as the one 98 * passed in, the periodic alarm continues, otherwise a new alarm is 99 * scheduled. If the callback returns 0, the periodic alarm is cancelled. 100 */ 101 typedef Uint32 (SDLCALL *SDL_NewTimerCallback)(Uint32 interval, void *param); 102 103 /** Definition of the timer ID type */ 104 typedef struct _SDL_TimerID *SDL_TimerID; 105 106 /** Add a new timer to the pool of timers already running. 107 * Returns a timer ID, or NULL when an error occurs. 108 */ 109 extern DECLSPEC SDL_TimerID SDLCALL SDL_AddTimer(Uint32 interval, SDL_NewTimerCallback callback, void *param); 110 111 /** 112 * Remove one of the multiple timers knowing its ID. 113 * Returns a boolean value indicating success. 114 */ 115 extern DECLSPEC SDL_bool SDLCALL SDL_RemoveTimer(SDL_TimerID t); 116 117 /*@}*/ 118 119 /* Ends C function definitions when using C++ */ 120 #ifdef __cplusplus 121 } 122 #endif 123 #include "close_code.h" 124 125 #endif /* _SDL_timer_h */ 126
