SDL  2.0
SDL_timer.h
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1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2018 Sam Lantinga <slouken@libsdl.org>
4 
5  This software is provided 'as-is', without any express or implied
6  warranty. In no event will the authors be held liable for any damages
7  arising from the use of this software.
8 
9  Permission is granted to anyone to use this software for any purpose,
10  including commercial applications, and to alter it and redistribute it
11  freely, subject to the following restrictions:
12 
13  1. The origin of this software must not be misrepresented; you must not
14  claim that you wrote the original software. If you use this software
15  in a product, an acknowledgment in the product documentation would be
16  appreciated but is not required.
17  2. Altered source versions must be plainly marked as such, and must not be
18  misrepresented as being the original software.
19  3. This notice may not be removed or altered from any source distribution.
20 */
21 
22 #ifndef SDL_timer_h_
23 #define SDL_timer_h_
24 
25 /**
26  * \file SDL_timer.h
27  *
28  * Header for the SDL time management routines.
29  */
30 
31 #include "SDL_stdinc.h"
32 #include "SDL_error.h"
33 
34 #include "begin_code.h"
35 /* Set up for C function definitions, even when using C++ */
36 #ifdef __cplusplus
37 extern "C" {
38 #endif
39 
40 /**
41  * \brief Get the number of milliseconds since the SDL library initialization.
42  *
43  * \note This value wraps if the program runs for more than ~49 days.
44  */
45 extern DECLSPEC Uint32 SDLCALL SDL_GetTicks(void);
46 
47 /**
48  * \brief Compare SDL ticks values, and return true if A has passed B
49  *
50  * e.g. if you want to wait 100 ms, you could do this:
51  * Uint32 timeout = SDL_GetTicks() + 100;
52  * while (!SDL_TICKS_PASSED(SDL_GetTicks(), timeout)) {
53  * ... do work until timeout has elapsed
54  * }
55  */
56 #define SDL_TICKS_PASSED(A, B) ((Sint32)((B) - (A)) <= 0)
57 
58 /**
59  * \brief Get the current value of the high resolution counter
60  */
61 extern DECLSPEC Uint64 SDLCALL SDL_GetPerformanceCounter(void);
62 
63 /**
64  * \brief Get the count per second of the high resolution counter
65  */
66 extern DECLSPEC Uint64 SDLCALL SDL_GetPerformanceFrequency(void);
67 
68 /**
69  * \brief Wait a specified number of milliseconds before returning.
70  */
71 extern DECLSPEC void SDLCALL SDL_Delay(Uint32 ms);
72 
73 /**
74  * Function prototype for the timer callback function.
75  *
76  * The callback function is passed the current timer interval and returns
77  * the next timer interval. If the returned value is the same as the one
78  * passed in, the periodic alarm continues, otherwise a new alarm is
79  * scheduled. If the callback returns 0, the periodic alarm is cancelled.
80  */
81 typedef Uint32 (SDLCALL * SDL_TimerCallback) (Uint32 interval, void *param);
82 
83 /**
84  * Definition of the timer ID type.
85  */
86 typedef int SDL_TimerID;
87 
88 /**
89  * \brief Add a new timer to the pool of timers already running.
90  *
91  * \return A timer ID, or 0 when an error occurs.
92  */
93 extern DECLSPEC SDL_TimerID SDLCALL SDL_AddTimer(Uint32 interval,
94  SDL_TimerCallback callback,
95  void *param);
96 
97 /**
98  * \brief Remove a timer knowing its ID.
99  *
100  * \return A boolean value indicating success or failure.
101  *
102  * \warning It is not safe to remove a timer multiple times.
103  */
104 extern DECLSPEC SDL_bool SDLCALL SDL_RemoveTimer(SDL_TimerID id);
105 
106 
107 /* Ends C function definitions when using C++ */
108 #ifdef __cplusplus
109 }
110 #endif
111 #include "close_code.h"
112 
113 #endif /* SDL_timer_h_ */
114 
115 /* vi: set ts=4 sw=4 expandtab: */