SDL 3.0
SDL_timer.h
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1/*
2 Simple DirectMedia Layer
3 Copyright (C) 1997-2024 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 <SDL3/SDL_stdinc.h>
32#include <SDL3/SDL_error.h>
33
34#include <SDL3/SDL_begin_code.h>
35/* Set up for C function definitions, even when using C++ */
36#ifdef __cplusplus
37extern "C" {
38#endif
39
40/* SDL time constants */
41#define SDL_MS_PER_SECOND 1000
42#define SDL_US_PER_SECOND 1000000
43#define SDL_NS_PER_SECOND 1000000000LL
44#define SDL_NS_PER_MS 1000000
45#define SDL_NS_PER_US 1000
46#define SDL_SECONDS_TO_NS(S) (((Uint64)(S)) * SDL_NS_PER_SECOND)
47#define SDL_NS_TO_SECONDS(NS) ((NS) / SDL_NS_PER_SECOND)
48#define SDL_MS_TO_NS(MS) (((Uint64)(MS)) * SDL_NS_PER_MS)
49#define SDL_NS_TO_MS(NS) ((NS) / SDL_NS_PER_MS)
50#define SDL_US_TO_NS(US) (((Uint64)(US)) * SDL_NS_PER_US)
51#define SDL_NS_TO_US(NS) ((NS) / SDL_NS_PER_US)
52
53/**
54 * Get the number of milliseconds since SDL library initialization.
55 *
56 * \returns an unsigned 64-bit value representing the number of milliseconds
57 * since the SDL library initialized.
58 *
59 * \since This function is available since SDL 3.0.0.
60 */
61extern DECLSPEC Uint64 SDLCALL SDL_GetTicks(void);
62
63/**
64 * Get the number of nanoseconds since SDL library initialization.
65 *
66 * \returns an unsigned 64-bit value representing the number of nanoseconds
67 * since the SDL library initialized.
68 *
69 * \since This function is available since SDL 3.0.0.
70 */
71extern DECLSPEC Uint64 SDLCALL SDL_GetTicksNS(void);
72
73/**
74 * Get the current value of the high resolution counter.
75 *
76 * This function is typically used for profiling.
77 *
78 * The counter values are only meaningful relative to each other. Differences
79 * between values can be converted to times by using
80 * SDL_GetPerformanceFrequency().
81 *
82 * \returns the current counter value.
83 *
84 * \since This function is available since SDL 3.0.0.
85 *
86 * \sa SDL_GetPerformanceFrequency
87 */
88extern DECLSPEC Uint64 SDLCALL SDL_GetPerformanceCounter(void);
89
90/**
91 * Get the count per second of the high resolution counter.
92 *
93 * \returns a platform-specific count per second.
94 *
95 * \since This function is available since SDL 3.0.0.
96 *
97 * \sa SDL_GetPerformanceCounter
98 */
99extern DECLSPEC Uint64 SDLCALL SDL_GetPerformanceFrequency(void);
100
101/**
102 * Wait a specified number of milliseconds before returning.
103 *
104 * This function waits a specified number of milliseconds before returning. It
105 * waits at least the specified time, but possibly longer due to OS
106 * scheduling.
107 *
108 * \param ms the number of milliseconds to delay
109 *
110 * \since This function is available since SDL 3.0.0.
111 */
112extern DECLSPEC void SDLCALL SDL_Delay(Uint32 ms);
113
114/**
115 * Wait a specified number of nanoseconds before returning.
116 *
117 * This function waits a specified number of nanoseconds before returning. It
118 * waits at least the specified time, but possibly longer due to OS
119 * scheduling.
120 *
121 * \param ns the number of nanoseconds to delay
122 *
123 * \since This function is available since SDL 3.0.0.
124 */
125extern DECLSPEC void SDLCALL SDL_DelayNS(Uint64 ns);
126
127/**
128 * Function prototype for the timer callback function.
129 *
130 * The callback function is passed the current timer interval and returns the
131 * next timer interval, in milliseconds. If the returned value is the same as
132 * the one passed in, the periodic alarm continues, otherwise a new alarm is
133 * scheduled. If the callback returns 0, the periodic alarm is cancelled.
134 *
135 * \param interval the current callback time interval.
136 * \param param an arbitrary pointer provided by the app through SDL_AddTimer,
137 * for its own use.
138 * \returns the new callback time interval, or 0 to disable further runs of
139 * the callback.
140 *
141 * \threadsafety SDL may call this callback at any time from a background
142 * thread; the application is responsible for locking resources
143 * the callback touches that need to be protected.
144 *
145 * \since This datatype is available since SDL 3.0.0.
146 *
147 * \sa SDL_AddTimer
148 */
149typedef Uint32 (SDLCALL *SDL_TimerCallback)(Uint32 interval, void *param);
150
151/**
152 * Definition of the timer ID type.
153 *
154 * \since This datatype is available since SDL 3.0.0.
155 */
157
158/**
159 * Call a callback function at a future time.
160 *
161 * If you use this function, you must pass `SDL_INIT_TIMER` to SDL_Init().
162 *
163 * The callback function is passed the current timer interval and the user
164 * supplied parameter from the SDL_AddTimer() call and should return the next
165 * timer interval. If the value returned from the callback is 0, the timer is
166 * canceled.
167 *
168 * The callback is run on a separate thread.
169 *
170 * Timers take into account the amount of time it took to execute the
171 * callback. For example, if the callback took 250 ms to execute and returned
172 * 1000 (ms), the timer would only wait another 750 ms before its next
173 * iteration.
174 *
175 * Timing may be inexact due to OS scheduling. Be sure to note the current
176 * time with SDL_GetTicksNS() or SDL_GetPerformanceCounter() in case your
177 * callback needs to adjust for variances.
178 *
179 * \param interval the timer delay, in milliseconds, passed to `callback`
180 * \param callback the SDL_TimerCallback function to call when the specified
181 * `interval` elapses
182 * \param param a pointer that is passed to `callback`
183 * \returns a timer ID or 0 if an error occurs; call SDL_GetError() for more
184 * information.
185 *
186 * \since This function is available since SDL 3.0.0.
187 *
188 * \sa SDL_RemoveTimer
189 */
190extern DECLSPEC SDL_TimerID SDLCALL SDL_AddTimer(Uint32 interval,
191 SDL_TimerCallback callback,
192 void *param);
193
194/**
195 * Remove a timer created with SDL_AddTimer().
196 *
197 * \param id the ID of the timer to remove
198 * \returns SDL_TRUE if the timer is removed or SDL_FALSE if the timer wasn't
199 * found.
200 *
201 * \since This function is available since SDL 3.0.0.
202 *
203 * \sa SDL_AddTimer
204 */
205extern DECLSPEC SDL_bool SDLCALL SDL_RemoveTimer(SDL_TimerID id);
206
207
208/* Ends C function definitions when using C++ */
209#ifdef __cplusplus
210}
211#endif
212#include <SDL3/SDL_close_code.h>
213
214#endif /* SDL_timer_h_ */
int SDL_bool
Definition SDL_stdinc.h:170
uint64_t Uint64
Definition SDL_stdinc.h:242
uint32_t Uint32
Definition SDL_stdinc.h:224
Uint32 SDL_TimerID
Definition SDL_timer.h:156
Uint32(* SDL_TimerCallback)(Uint32 interval, void *param)
Definition SDL_timer.h:149
SDL_bool SDL_RemoveTimer(SDL_TimerID id)
Uint64 SDL_GetPerformanceFrequency(void)
Uint64 SDL_GetPerformanceCounter(void)
SDL_TimerID SDL_AddTimer(Uint32 interval, SDL_TimerCallback callback, void *param)
void SDL_Delay(Uint32 ms)
void SDL_DelayNS(Uint64 ns)
Uint64 SDL_GetTicksNS(void)
Uint64 SDL_GetTicks(void)