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 * # CategoryTimer
27 *
28 * 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 SDL_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 SDL_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 SDL_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 SDL_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 SDL_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 * will attempt to wait as close to the requested time as possible, busy
119 * waiting if necessary, but could return later due to OS 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 SDL_DECLSPEC void SDLCALL SDL_DelayNS(Uint64 ns);
126
127/**
128 * Definition of the timer ID type.
129 *
130 * \since This datatype is available since SDL 3.0.0.
131 */
133
134/**
135 * Function prototype for the millisecond timer callback function.
136 *
137 * The callback function is passed the current timer interval and returns the
138 * next timer interval, in milliseconds. If the returned value is the same as
139 * the one passed in, the periodic alarm continues, otherwise a new alarm is
140 * scheduled. If the callback returns 0, the periodic alarm is cancelled.
141 *
142 * \param userdata an arbitrary pointer provided by the app through
143 * SDL_AddTimer, for its own use.
144 * \param timerID the current timer being processed.
145 * \param interval the current callback time interval.
146 * \returns the new callback time interval, or 0 to disable further runs of
147 * the callback.
148 *
149 * \threadsafety SDL may call this callback at any time from a background
150 * thread; the application is responsible for locking resources
151 * the callback touches that need to be protected.
152 *
153 * \since This datatype is available since SDL 3.0.0.
154 *
155 * \sa SDL_AddTimer
156 */
157typedef Uint32 (SDLCALL *SDL_TimerCallback)(void *userdata, SDL_TimerID timerID, Uint32 interval);
158
159/**
160 * Call a callback function at a future time.
161 *
162 * If you use this function, you must pass `SDL_INIT_TIMER` to SDL_Init().
163 *
164 * The callback function is passed the current timer interval and the user
165 * supplied parameter from the SDL_AddTimer() call and should return the next
166 * timer interval. If the value returned from the callback is 0, the timer is
167 * canceled.
168 *
169 * The callback is run on a separate thread, and for short timeouts can
170 * potentially be called before this function returns.
171 *
172 * Timers take into account the amount of time it took to execute the
173 * callback. For example, if the callback took 250 ms to execute and returned
174 * 1000 (ms), the timer would only wait another 750 ms before its next
175 * iteration.
176 *
177 * Timing may be inexact due to OS scheduling. Be sure to note the current
178 * time with SDL_GetTicksNS() or SDL_GetPerformanceCounter() in case your
179 * callback needs to adjust for variances.
180 *
181 * \param interval the timer delay, in milliseconds, passed to `callback`.
182 * \param callback the SDL_TimerCallback function to call when the specified
183 * `interval` elapses.
184 * \param userdata a pointer that is passed to `callback`.
185 * \returns a timer ID or 0 on failure; call SDL_GetError() for more
186 * information.
187 *
188 * \threadsafety It is safe to call this function from any thread.
189 *
190 * \since This function is available since SDL 3.0.0.
191 *
192 * \sa SDL_AddTimerNS
193 * \sa SDL_RemoveTimer
194 */
195extern SDL_DECLSPEC SDL_TimerID SDLCALL SDL_AddTimer(Uint32 interval, SDL_TimerCallback callback, void *userdata);
196
197/**
198 * Function prototype for the nanosecond timer callback function.
199 *
200 * The callback function is passed the current timer interval and returns the
201 * next timer interval, in nanoseconds. If the returned value is the same as
202 * the one passed in, the periodic alarm continues, otherwise a new alarm is
203 * scheduled. If the callback returns 0, the periodic alarm is cancelled.
204 *
205 * \param userdata an arbitrary pointer provided by the app through
206 * SDL_AddTimer, for its own use.
207 * \param timerID the current timer being processed.
208 * \param interval the current callback time interval.
209 * \returns the new callback time interval, or 0 to disable further runs of
210 * the callback.
211 *
212 * \threadsafety SDL may call this callback at any time from a background
213 * thread; the application is responsible for locking resources
214 * the callback touches that need to be protected.
215 *
216 * \since This datatype is available since SDL 3.0.0.
217 *
218 * \sa SDL_AddTimerNS
219 */
220typedef Uint64 (SDLCALL *SDL_NSTimerCallback)(void *userdata, SDL_TimerID timerID, Uint64 interval);
221
222/**
223 * Call a callback function at a future time.
224 *
225 * If you use this function, you must pass `SDL_INIT_TIMER` to SDL_Init().
226 *
227 * The callback function is passed the current timer interval and the user
228 * supplied parameter from the SDL_AddTimerNS() call and should return the
229 * next timer interval. If the value returned from the callback is 0, the
230 * timer is canceled.
231 *
232 * The callback is run on a separate thread, and for short timeouts can
233 * potentially be called before this function returns.
234 *
235 * Timers take into account the amount of time it took to execute the
236 * callback. For example, if the callback took 250 ns to execute and returned
237 * 1000 (ns), the timer would only wait another 750 ns before its next
238 * iteration.
239 *
240 * Timing may be inexact due to OS scheduling. Be sure to note the current
241 * time with SDL_GetTicksNS() or SDL_GetPerformanceCounter() in case your
242 * callback needs to adjust for variances.
243 *
244 * \param interval the timer delay, in nanoseconds, passed to `callback`.
245 * \param callback the SDL_TimerCallback function to call when the specified
246 * `interval` elapses.
247 * \param userdata a pointer that is passed to `callback`.
248 * \returns a timer ID or 0 on failure; call SDL_GetError() for more
249 * information.
250 *
251 * \threadsafety It is safe to call this function from any thread.
252 *
253 * \since This function is available since SDL 3.0.0.
254 *
255 * \sa SDL_AddTimer
256 * \sa SDL_RemoveTimer
257 */
258extern SDL_DECLSPEC SDL_TimerID SDLCALL SDL_AddTimerNS(Uint64 interval, SDL_NSTimerCallback callback, void *userdata);
259
260/**
261 * Remove a timer created with SDL_AddTimer().
262 *
263 * \param id the ID of the timer to remove.
264 * \returns 0 on success or a negative error code on failure; call
265 * SDL_GetError() for more information.
266 *
267 * \since This function is available since SDL 3.0.0.
268 *
269 * \sa SDL_AddTimer
270 */
271extern SDL_DECLSPEC int SDLCALL SDL_RemoveTimer(SDL_TimerID id);
272
273
274/* Ends C function definitions when using C++ */
275#ifdef __cplusplus
276}
277#endif
278#include <SDL3/SDL_close_code.h>
279
280#endif /* SDL_timer_h_ */
uint64_t Uint64
Definition SDL_stdinc.h:287
uint32_t Uint32
Definition SDL_stdinc.h:265
Uint32 SDL_TimerID
Definition SDL_timer.h:132
SDL_TimerID SDL_AddTimer(Uint32 interval, SDL_TimerCallback callback, void *userdata)
Uint64 SDL_GetPerformanceFrequency(void)
Uint64 SDL_GetPerformanceCounter(void)
SDL_TimerID SDL_AddTimerNS(Uint64 interval, SDL_NSTimerCallback callback, void *userdata)
Uint64(* SDL_NSTimerCallback)(void *userdata, SDL_TimerID timerID, Uint64 interval)
Definition SDL_timer.h:220
void SDL_Delay(Uint32 ms)
void SDL_DelayNS(Uint64 ns)
Uint64 SDL_GetTicksNS(void)
Uint32(* SDL_TimerCallback)(void *userdata, SDL_TimerID timerID, Uint32 interval)
Definition SDL_timer.h:157
int SDL_RemoveTimer(SDL_TimerID id)
Uint64 SDL_GetTicks(void)