1 /* 2 SDL - Simple DirectMedia Layer 3 Copyright (C) 1997-2004 Sam Lantinga 4 5 This library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Library General Public 7 License as published by the Free Software Foundation; either 8 version 2 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 Library General Public License for more details. 14 15 You should have received a copy of the GNU Library General Public 16 License along with this library; if not, write to the Free 17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 18 19 Sam Lantinga 20 slouken (at) libsdl.org 21 */ 22 23 #ifdef SAVE_RCSID 24 static char rcsid = 25 "@(#) $Id: SDL_timer.h,v 1.6 2004/01/04 16:49:08 slouken Exp $"; 26 #endif 27 28 #ifndef _SDL_timer_h 29 #define _SDL_timer_h 30 31 /* Header for the SDL time management routines */ 32 33 #include "SDL_main.h" 34 #include "SDL_types.h" 35 36 #include "begin_code.h" 37 /* Set up for C function definitions, even when using C++ */ 38 #ifdef __cplusplus 39 extern "C" { 40 #endif 41 42 /* This is the OS scheduler timeslice, in milliseconds */ 43 #define SDL_TIMESLICE 10 44 45 /* This is the maximum resolution of the SDL timer on all platforms */ 46 #define TIMER_RESOLUTION 10 /* Experimentally determined */ 47 48 /* Get the number of milliseconds since the SDL library initialization. 49 * Note that this value wraps if the program runs for more than ~49 days. 50 */ 51 extern DECLSPEC Uint32 SDLCALL SDL_GetTicks(void); 52 53 /* Wait a specified number of milliseconds before returning */ 54 extern DECLSPEC void SDLCALL SDL_Delay(Uint32 ms); 55 56 /* Function prototype for the timer callback function */ 57 typedef Uint32 (SDLCALL *SDL_TimerCallback)(Uint32 interval); 58 59 /* Set a callback to run after the specified number of milliseconds has 60 * elapsed. The callback function is passed the current timer interval 61 * and returns the next timer interval. If the returned value is the 62 * same as the one passed in, the periodic alarm continues, otherwise a 63 * new alarm is scheduled. If the callback returns 0, the periodic alarm 64 * is cancelled. 65 * 66 * To cancel a currently running timer, call SDL_SetTimer(0, NULL); 67 * 68 * The timer callback function may run in a different thread than your 69 * main code, and so shouldn't call any functions from within itself. 70 * 71 * The maximum resolution of this timer is 10 ms, which means that if 72 * you request a 16 ms timer, your callback will run approximately 20 ms 73 * later on an unloaded system. If you wanted to set a flag signaling 74 * a frame update at 30 frames per second (every 33 ms), you might set a 75 * timer for 30 ms: 76 * SDL_SetTimer((33/10)*10, flag_update); 77 * 78 * If you use this function, you need to pass SDL_INIT_TIMER to SDL_Init(). 79 * 80 * Under UNIX, you should not use raise or use SIGALRM and this function 81 * in the same program, as it is implemented using setitimer(). You also 82 * should not use this function in multi-threaded applications as signals 83 * to multi-threaded apps have undefined behavior in some implementations. 84 */ 85 extern DECLSPEC int SDLCALL SDL_SetTimer(Uint32 interval, SDL_TimerCallback callback); 86 87 /* New timer API, supports multiple timers 88 * Written by Stephane Peter <megastep (at) lokigames.com> 89 */ 90 91 /* Function prototype for the new timer callback function. 92 * The callback function is passed the current timer interval and returns 93 * the next timer interval. If the returned value is the same as the one 94 * passed in, the periodic alarm continues, otherwise a new alarm is 95 * scheduled. If the callback returns 0, the periodic alarm is cancelled. 96 */ 97 typedef Uint32 (SDLCALL *SDL_NewTimerCallback)(Uint32 interval, void *param); 98 99 /* Definition of the timer ID type */ 100 typedef struct _SDL_TimerID *SDL_TimerID; 101 102 /* Add a new timer to the pool of timers already running. 103 Returns a timer ID, or NULL when an error occurs. 104 */ 105 extern DECLSPEC SDL_TimerID SDLCALL SDL_AddTimer(Uint32 interval, SDL_NewTimerCallback callback, void *param); 106 107 /* Remove one of the multiple timers knowing its ID. 108 * Returns a boolean value indicating success. 109 */ 110 extern DECLSPEC SDL_bool SDLCALL SDL_RemoveTimer(SDL_TimerID t); 111 112 /* Ends C function definitions when using C++ */ 113 #ifdef __cplusplus 114 } 115 #endif 116 #include "close_code.h" 117 118 #endif /* _SDL_timer_h */ 119
