e14743d1 |
1 | /* |
2 | SDL - Simple DirectMedia Layer |
3 | Copyright (C) 1997-2009 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@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@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 */ |