SDL 3.0
SDL_timer.h File Reference
+ Include dependency graph for SDL_timer.h:
+ This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Macros

#define SDL_MS_PER_SECOND   1000
 
#define SDL_US_PER_SECOND   1000000
 
#define SDL_NS_PER_SECOND   1000000000LL
 
#define SDL_NS_PER_MS   1000000
 
#define SDL_NS_PER_US   1000
 
#define SDL_SECONDS_TO_NS(S)
 
#define SDL_NS_TO_SECONDS(NS)
 
#define SDL_MS_TO_NS(MS)
 
#define SDL_NS_TO_MS(NS)
 
#define SDL_US_TO_NS(US)
 
#define SDL_NS_TO_US(NS)
 

Typedefs

typedef Uint32 SDL_TimerID
 
typedef Uint32(* SDL_TimerCallback) (void *userdata, SDL_TimerID timerID, Uint32 interval)
 
typedef Uint64(* SDL_NSTimerCallback) (void *userdata, SDL_TimerID timerID, Uint64 interval)
 

Functions

Uint64 SDL_GetTicks (void)
 
Uint64 SDL_GetTicksNS (void)
 
Uint64 SDL_GetPerformanceCounter (void)
 
Uint64 SDL_GetPerformanceFrequency (void)
 
void SDL_Delay (Uint32 ms)
 
void SDL_DelayNS (Uint64 ns)
 
void SDL_DelayPrecise (Uint64 ns)
 
SDL_TimerID SDL_AddTimer (Uint32 interval, SDL_TimerCallback callback, void *userdata)
 
SDL_TimerID SDL_AddTimerNS (Uint64 interval, SDL_NSTimerCallback callback, void *userdata)
 
bool SDL_RemoveTimer (SDL_TimerID id)
 

Macro Definition Documentation

◆ SDL_MS_PER_SECOND

#define SDL_MS_PER_SECOND   1000

CategoryTimer

SDL provides time management functionality. It is useful for dealing with (usually) small durations of time.

This is not to be confused with calendar time management, which is provided by [CategoryTime](CategoryTime).

This category covers measuring time elapsed (SDL_GetTicks(), SDL_GetPerformanceCounter()), putting a thread to sleep for a certain amount of time (SDL_Delay(), SDL_DelayNS(), SDL_DelayPrecise()), and firing a callback function after a certain amount of time has elasped (SDL_AddTimer(), etc).

There are also useful macros to convert between time units, like SDL_SECONDS_TO_NS() and such. Number of milliseconds in a second.

This is always 1000.

Since
This macro is available since SDL 3.2.0.

Definition at line 62 of file SDL_timer.h.

◆ SDL_MS_TO_NS

#define SDL_MS_TO_NS ( MS)
Value:
(((Uint64)(MS)) * SDL_NS_PER_MS)
uint64_t Uint64
Definition SDL_stdinc.h:483
#define SDL_NS_PER_MS
Definition SDL_timer.h:89

Convert milliseconds to nanoseconds.

This only converts whole numbers, not fractional milliseconds.

Parameters
MSthe number of milliseconds to convert.
Returns
MS, expressed in nanoseconds.

\threadsafety It is safe to call this macro from any thread.

Since
This macro is available since SDL 3.2.0.

Definition at line 141 of file SDL_timer.h.

◆ SDL_NS_PER_MS

#define SDL_NS_PER_MS   1000000

Number of nanoseconds in a millisecond.

This is always 1000000.

Since
This macro is available since SDL 3.2.0.

Definition at line 89 of file SDL_timer.h.

◆ SDL_NS_PER_SECOND

#define SDL_NS_PER_SECOND   1000000000LL

Number of nanoseconds in a second.

This is always 1000000000.

Since
This macro is available since SDL 3.2.0.

Definition at line 80 of file SDL_timer.h.

◆ SDL_NS_PER_US

#define SDL_NS_PER_US   1000

Number of nanoseconds in a microsecond.

This is always 1000.

Since
This macro is available since SDL 3.2.0.

Definition at line 98 of file SDL_timer.h.

◆ SDL_NS_TO_MS

#define SDL_NS_TO_MS ( NS)
Value:
((NS) / SDL_NS_PER_MS)

Convert nanoseconds to milliseconds.

This performs a division, so the results can be dramatically different if NS is an integer or floating point value.

Parameters
NSthe number of nanoseconds to convert.
Returns
NS, expressed in milliseconds.

\threadsafety It is safe to call this macro from any thread.

Since
This macro is available since SDL 3.2.0.

Definition at line 156 of file SDL_timer.h.

◆ SDL_NS_TO_SECONDS

#define SDL_NS_TO_SECONDS ( NS)
Value:
#define SDL_NS_PER_SECOND
Definition SDL_timer.h:80

Convert nanoseconds to seconds.

This performs a division, so the results can be dramatically different if NS is an integer or floating point value.

Parameters
NSthe number of nanoseconds to convert.
Returns
NS, expressed in seconds.

\threadsafety It is safe to call this macro from any thread.

Since
This macro is available since SDL 3.2.0.

Definition at line 127 of file SDL_timer.h.

◆ SDL_NS_TO_US

#define SDL_NS_TO_US ( NS)
Value:
((NS) / SDL_NS_PER_US)
#define SDL_NS_PER_US
Definition SDL_timer.h:98

Convert nanoseconds to microseconds.

This performs a division, so the results can be dramatically different if NS is an integer or floating point value.

Parameters
NSthe number of nanoseconds to convert.
Returns
NS, expressed in microseconds.

\threadsafety It is safe to call this macro from any thread.

Since
This macro is available since SDL 3.2.0.

Definition at line 185 of file SDL_timer.h.

◆ SDL_SECONDS_TO_NS

#define SDL_SECONDS_TO_NS ( S)
Value:

Convert seconds to nanoseconds.

This only converts whole numbers, not fractional seconds.

Parameters
Sthe number of seconds to convert.
Returns
S, expressed in nanoseconds.

\threadsafety It is safe to call this macro from any thread.

Since
This macro is available since SDL 3.2.0.

Definition at line 112 of file SDL_timer.h.

◆ SDL_US_PER_SECOND

#define SDL_US_PER_SECOND   1000000

Number of microseconds in a second.

This is always 1000000.

Since
This macro is available since SDL 3.2.0.

Definition at line 71 of file SDL_timer.h.

◆ SDL_US_TO_NS

#define SDL_US_TO_NS ( US)
Value:
(((Uint64)(US)) * SDL_NS_PER_US)

Convert microseconds to nanoseconds.

This only converts whole numbers, not fractional microseconds.

Parameters
USthe number of microseconds to convert.
Returns
US, expressed in nanoseconds.

\threadsafety It is safe to call this macro from any thread.

Since
This macro is available since SDL 3.2.0.

Definition at line 170 of file SDL_timer.h.

Typedef Documentation

◆ SDL_NSTimerCallback

typedef Uint64(* SDL_NSTimerCallback) (void *userdata, SDL_TimerID timerID, Uint64 interval)

Function prototype for the nanosecond timer callback function.

The callback function is passed the current timer interval and returns the next timer interval, in nanoseconds. If the returned value is the same as the one passed in, the periodic alarm continues, otherwise a new alarm is scheduled. If the callback returns 0, the periodic alarm is canceled and will be removed.

Parameters
userdataan arbitrary pointer provided by the app through SDL_AddTimer, for its own use.
timerIDthe current timer being processed.
intervalthe current callback time interval.
Returns
the new callback time interval, or 0 to disable further runs of the callback.

\threadsafety SDL may call this callback at any time from a background thread; the application is responsible for locking resources the callback touches that need to be protected.

Since
This datatype is available since SDL 3.2.0.
See also
SDL_AddTimerNS

Definition at line 390 of file SDL_timer.h.

◆ SDL_TimerCallback

typedef Uint32(* SDL_TimerCallback) (void *userdata, SDL_TimerID timerID, Uint32 interval)

Function prototype for the millisecond timer callback function.

The callback function is passed the current timer interval and returns the next timer interval, in milliseconds. If the returned value is the same as the one passed in, the periodic alarm continues, otherwise a new alarm is scheduled. If the callback returns 0, the periodic alarm is canceled and will be removed.

Parameters
userdataan arbitrary pointer provided by the app through SDL_AddTimer, for its own use.
timerIDthe current timer being processed.
intervalthe current callback time interval.
Returns
the new callback time interval, or 0 to disable further runs of the callback.

\threadsafety SDL may call this callback at any time from a background thread; the application is responsible for locking resources the callback touches that need to be protected.

Since
This datatype is available since SDL 3.2.0.
See also
SDL_AddTimer

Definition at line 328 of file SDL_timer.h.

◆ SDL_TimerID

Definition of the timer ID type.

Since
This datatype is available since SDL 3.2.0.

Definition at line 302 of file SDL_timer.h.

Function Documentation

◆ SDL_AddTimer()

SDL_TimerID SDL_AddTimer ( Uint32 interval,
SDL_TimerCallback callback,
void * userdata )
extern

Call a callback function at a future time.

The callback function is passed the current timer interval and the user supplied parameter from the SDL_AddTimer() call and should return the next timer interval. If the value returned from the callback is 0, the timer is canceled and will be removed.

The callback is run on a separate thread, and for short timeouts can potentially be called before this function returns.

Timers take into account the amount of time it took to execute the callback. For example, if the callback took 250 ms to execute and returned 1000 (ms), the timer would only wait another 750 ms before its next iteration.

Timing may be inexact due to OS scheduling. Be sure to note the current time with SDL_GetTicksNS() or SDL_GetPerformanceCounter() in case your callback needs to adjust for variances.

Parameters
intervalthe timer delay, in milliseconds, passed to callback.
callbackthe SDL_TimerCallback function to call when the specified interval elapses.
userdataa pointer that is passed to callback.
Returns
a timer ID or 0 on failure; call SDL_GetError() for more information.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.2.0.
See also
SDL_AddTimerNS
SDL_RemoveTimer

◆ SDL_AddTimerNS()

SDL_TimerID SDL_AddTimerNS ( Uint64 interval,
SDL_NSTimerCallback callback,
void * userdata )
extern

Call a callback function at a future time.

The callback function is passed the current timer interval and the user supplied parameter from the SDL_AddTimerNS() call and should return the next timer interval. If the value returned from the callback is 0, the timer is canceled and will be removed.

The callback is run on a separate thread, and for short timeouts can potentially be called before this function returns.

Timers take into account the amount of time it took to execute the callback. For example, if the callback took 250 ns to execute and returned 1000 (ns), the timer would only wait another 750 ns before its next iteration.

Timing may be inexact due to OS scheduling. Be sure to note the current time with SDL_GetTicksNS() or SDL_GetPerformanceCounter() in case your callback needs to adjust for variances.

Parameters
intervalthe timer delay, in nanoseconds, passed to callback.
callbackthe SDL_TimerCallback function to call when the specified interval elapses.
userdataa pointer that is passed to callback.
Returns
a timer ID or 0 on failure; call SDL_GetError() for more information.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.2.0.
See also
SDL_AddTimer
SDL_RemoveTimer

◆ SDL_Delay()

void SDL_Delay ( Uint32 ms)
extern

Wait a specified number of milliseconds before returning.

This function waits a specified number of milliseconds before returning. It waits at least the specified time, but possibly longer due to OS scheduling.

Parameters
msthe number of milliseconds to delay.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.2.0.
See also
SDL_DelayNS
SDL_DelayPrecise

◆ SDL_DelayNS()

void SDL_DelayNS ( Uint64 ns)
extern

Wait a specified number of nanoseconds before returning.

This function waits a specified number of nanoseconds before returning. It waits at least the specified time, but possibly longer due to OS scheduling.

Parameters
nsthe number of nanoseconds to delay.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.2.0.
See also
SDL_Delay
SDL_DelayPrecise

◆ SDL_DelayPrecise()

void SDL_DelayPrecise ( Uint64 ns)
extern

Wait a specified number of nanoseconds before returning.

This function waits a specified number of nanoseconds before returning. It will attempt to wait as close to the requested time as possible, busy waiting if necessary, but could return later due to OS scheduling.

Parameters
nsthe number of nanoseconds to delay.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.2.0.
See also
SDL_Delay
SDL_DelayNS

◆ SDL_GetPerformanceCounter()

Uint64 SDL_GetPerformanceCounter ( void )
extern

Get the current value of the high resolution counter.

This function is typically used for profiling.

The counter values are only meaningful relative to each other. Differences between values can be converted to times by using SDL_GetPerformanceFrequency().

Returns
the current counter value.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.2.0.
See also
SDL_GetPerformanceFrequency

◆ SDL_GetPerformanceFrequency()

Uint64 SDL_GetPerformanceFrequency ( void )
extern

Get the count per second of the high resolution counter.

Returns
a platform-specific count per second.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.2.0.
See also
SDL_GetPerformanceCounter

◆ SDL_GetTicks()

Uint64 SDL_GetTicks ( void )
extern

Get the number of milliseconds since SDL library initialization.

Returns
an unsigned 64-bit value representing the number of milliseconds since the SDL library initialized.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.2.0.

◆ SDL_GetTicksNS()

Uint64 SDL_GetTicksNS ( void )
extern

Get the number of nanoseconds since SDL library initialization.

Returns
an unsigned 64-bit value representing the number of nanoseconds since the SDL library initialized.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.2.0.

◆ SDL_RemoveTimer()

bool SDL_RemoveTimer ( SDL_TimerID id)
extern

Remove a timer created with SDL_AddTimer().

Parameters
idthe ID of the timer to remove.
Returns
true on success or false on failure; call SDL_GetError() for more information.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.2.0.
See also
SDL_AddTimer