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 canceled and
141 * will be removed.
142 *
143 * \param userdata an arbitrary pointer provided by the app through
144 * SDL_AddTimer, for its own use.
145 * \param timerID the current timer being processed.
146 * \param interval the current callback time interval.
147 * \returns the new callback time interval, or 0 to disable further runs of
148 * the callback.
149 *
150 * \threadsafety SDL may call this callback at any time from a background
151 * thread; the application is responsible for locking resources
152 * the callback touches that need to be protected.
153 *
154 * \since This datatype is available since SDL 3.0.0.
155 *
156 * \sa SDL_AddTimer
157 */
158typedef Uint32 (SDLCALL *SDL_TimerCallback)(void *userdata, SDL_TimerID timerID, Uint32 interval);
159
160/**
161 * Call a callback function at a future time.
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 and will be removed.
167 *
168 * The callback is run on a separate thread, and for short timeouts can
169 * potentially be called before this function returns.
170 *
171 * Timers take into account the amount of time it took to execute the
172 * callback. For example, if the callback took 250 ms to execute and returned
173 * 1000 (ms), the timer would only wait another 750 ms before its next
174 * iteration.
175 *
176 * Timing may be inexact due to OS scheduling. Be sure to note the current
177 * time with SDL_GetTicksNS() or SDL_GetPerformanceCounter() in case your
178 * callback needs to adjust for variances.
179 *
180 * \param interval the timer delay, in milliseconds, passed to `callback`.
181 * \param callback the SDL_TimerCallback function to call when the specified
182 * `interval` elapses.
183 * \param userdata a pointer that is passed to `callback`.
184 * \returns a timer ID or 0 on failure; call SDL_GetError() for more
185 * information.
186 *
187 * \threadsafety It is safe to call this function from any thread.
188 *
189 * \since This function is available since SDL 3.0.0.
190 *
191 * \sa SDL_AddTimerNS
192 * \sa SDL_RemoveTimer
193 */
194extern SDL_DECLSPEC SDL_TimerID SDLCALL SDL_AddTimer(Uint32 interval, SDL_TimerCallback callback, void *userdata);
195
196/**
197 * Function prototype for the nanosecond timer callback function.
198 *
199 * The callback function is passed the current timer interval and returns the
200 * next timer interval, in nanoseconds. If the returned value is the same as
201 * the one passed in, the periodic alarm continues, otherwise a new alarm is
202 * scheduled. If the callback returns 0, the periodic alarm is canceled and
203 * will be removed.
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 * The callback function is passed the current timer interval and the user
226 * supplied parameter from the SDL_AddTimerNS() call and should return the
227 * next timer interval. If the value returned from the callback is 0, the
228 * timer is canceled and will be removed.
229 *
230 * The callback is run on a separate thread, and for short timeouts can
231 * potentially be called before this function returns.
232 *
233 * Timers take into account the amount of time it took to execute the
234 * callback. For example, if the callback took 250 ns to execute and returned
235 * 1000 (ns), the timer would only wait another 750 ns before its next
236 * iteration.
237 *
238 * Timing may be inexact due to OS scheduling. Be sure to note the current
239 * time with SDL_GetTicksNS() or SDL_GetPerformanceCounter() in case your
240 * callback needs to adjust for variances.
241 *
242 * \param interval the timer delay, in nanoseconds, passed to `callback`.
243 * \param callback the SDL_TimerCallback function to call when the specified
244 * `interval` elapses.
245 * \param userdata a pointer that is passed to `callback`.
246 * \returns a timer ID or 0 on failure; call SDL_GetError() for more
247 * information.
248 *
249 * \threadsafety It is safe to call this function from any thread.
250 *
251 * \since This function is available since SDL 3.0.0.
252 *
253 * \sa SDL_AddTimer
254 * \sa SDL_RemoveTimer
255 */
256extern SDL_DECLSPEC SDL_TimerID SDLCALL SDL_AddTimerNS(Uint64 interval, SDL_NSTimerCallback callback, void *userdata);
257
258/**
259 * Remove a timer created with SDL_AddTimer().
260 *
261 * \param id the ID of the timer to remove.
262 * \returns SDL_TRUE on success or SDL_FALSE on failure; call SDL_GetError()
263 * for more information.
264 *
265 * \since This function is available since SDL 3.0.0.
266 *
267 * \sa SDL_AddTimer
268 */
269extern SDL_DECLSPEC SDL_bool SDLCALL SDL_RemoveTimer(SDL_TimerID id);
270
271
272/* Ends C function definitions when using C++ */
273#ifdef __cplusplus
274}
275#endif
276#include <SDL3/SDL_close_code.h>
277
278#endif /* SDL_timer_h_ */
uint64_t Uint64
Definition SDL_stdinc.h:375
uint32_t Uint32
Definition SDL_stdinc.h:353
bool SDL_bool
Definition SDL_stdinc.h:301
Uint32 SDL_TimerID
Definition SDL_timer.h:132
SDL_TimerID SDL_AddTimer(Uint32 interval, SDL_TimerCallback callback, void *userdata)
SDL_bool SDL_RemoveTimer(SDL_TimerID id)
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:158
Uint64 SDL_GetTicks(void)