SDL::AtomicU32 Class Reference

A type representing an atomic unsigned 32-bit value. More...

Public Member Functions
constexpr	AtomicU32 (Uint32 value=0)
	Constructor.
	AtomicU32 (const AtomicU32 &value)=delete
AtomicU32 &	operator= (const AtomicU32 &value)=delete
constexpr	operator SDL_AtomicU32 * ()
	Convert to underlying type.
bool	CompareAndSwap (Uint32 oldval, Uint32 newval)
	Set an atomic variable to a new value if it is currently an old value.
Uint32	Set (Uint32 v)
	Set an atomic variable to a value.
Uint32	Get ()
	Get the value of an atomic variable.

Detailed Description

This can be used to manage a value that is synchronized across multiple CPUs without a race condition; when an app sets a value with AtomicU32.Set all other threads, regardless of the CPU it is running on, will see that value when retrieved with AtomicU32.Get, regardless of CPU caches, etc.

This is also useful for atomic compare-and-swap operations: a thread can change the value as long as its current value matches expectations. When done in a loop, one can guarantee data consistency across threads without a lock (but the usual warnings apply: if you don't know what you're doing, or you don't do it carefully, you can confidently cause any number of disasters with this, so in most cases, you should use a mutex instead of this!).

This is a struct so people don't accidentally use numeric operations on it directly. You have to use SDL atomic functions.

Since

This struct is available since SDL 3.2.0.

See also

AtomicU32.CompareAndSwap

AtomicU32.Get

AtomicU32.Set

Member Function Documentation

CompareAndSwap()

bool SDL::AtomicU32::CompareAndSwap ( Uint32  oldval, Uint32  newval  )

inline

Note: If you don't know what this function is for, you shouldn't use it!

Parameters

oldval	the old value.
newval	the new value.

Returns

true if the atomic variable was set, false otherwise.

Thread safety:

It is safe to call this function from any thread.

Since

This function is available since SDL 3.2.0.

See also

AtomicU32.Get

AtomicU32.Set

Get()

Uint32 SDL::AtomicU32::Get ( )

inline

Note: If you don't know what this function is for, you shouldn't use it!

Returns

the current value of an atomic variable.

Thread safety:

It is safe to call this function from any thread.

Since

This function is available since SDL 3.2.0.

See also

AtomicU32.Set

Set()

Uint32 SDL::AtomicU32::Set ( Uint32  v )

inline

This function also acts as a full memory barrier.

Note: If you don't know what this function is for, you shouldn't use it!

Parameters

v	the desired value.

Returns

the previous value of the atomic variable.

Thread safety:

It is safe to call this function from any thread.

Since

This function is available since SDL 3.2.0.

See also

AtomicU32.Get

---

The documentation for this class was generated from the following file:

• SDL3pp/SDL3pp_atomic.h