include/SDL_timer.h
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FUNCTIONS
This source file includes following functions.
1 /*
2 SDL - Simple DirectMedia Layer
3 Copyright (C) 1997, 1998, 1999, 2000, 2001 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@devolution.com
21 */
22
23 #ifdef SAVE_RCSID
24 static char rcsid =
25 "@(#) $Id: SDL_timer.h,v 1.4.2.8 2001/02/17 01:45:30 hercules 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 SDL_GetTicks(void);
52
53 /* Wait a specified number of milliseconds before returning */
54 extern DECLSPEC void SDL_Delay(Uint32 ms);
55
56 /* Function prototype for the timer callback function */
57 typedef Uint32 (*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 SDL_SetTimer(Uint32 interval, SDL_TimerCallback callback);
86
87 /* New timer API, supports multiple timers
88 * Written by Stephane Peter <megastep@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 (*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 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 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 */