Added Uint32 versions of the atomic functions

include/SDL3/SDL_atomic.h

@@ -316,7 +316,7 @@ typedef void (*SDL_KernelMemoryBarrierFunc)();
  * this!).
  *
  * This is a struct so people don't accidentally use numeric operations on it
- * directly. You have to use SDL_Atomic* functions.
+ * directly. You have to use SDL atomic functions.
  *
  * \since This struct is available since SDL 3.0.0.
  *
@@ -342,7 +342,8 @@ typedef struct SDL_AtomicInt { int value; } SDL_AtomicInt;
  *
  * \since This function is available since SDL 3.0.0.
  *
- * \sa SDL_CompareAndSwapAtomicPointer
+ * \sa SDL_GetAtomicInt
+ * \sa SDL_SetAtomicInt
  */
 extern SDL_DECLSPEC SDL_bool SDLCALL SDL_CompareAndSwapAtomicInt(SDL_AtomicInt *a, int oldval, int newval);
 
@@ -439,6 +440,91 @@ extern SDL_DECLSPEC int SDLCALL SDL_AddAtomicInt(SDL_AtomicInt *a, int v);
 #define SDL_AtomicDecRef(a)    (SDL_AddAtomicInt(a, -1) == 1)
 #endif
 
+/**
+ * A type representing an atomic unsigned 32-bit value.
+ *
+ * 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 SDL_SetAtomicU32
+ * all other threads, regardless of the CPU it is running on, will see that
+ * value when retrieved with SDL_GetAtomicU32, 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 3.0.0.
+ *
+ * \sa SDL_CompareAndSwapAtomicU32
+ * \sa SDL_GetAtomicU32
+ * \sa SDL_SetAtomicU32
+ * \sa SDL_AddAtomicU32
+ */
+typedef struct SDL_AtomicU32 { Uint32 value; } SDL_AtomicU32;
+
+/**
+ * Set an atomic variable to a new value if it is currently an old value.
+ *
+ * ***Note: If you don't know what this function is for, you shouldn't use
+ * it!***
+ *
+ * \param a a pointer to an SDL_AtomicU32 variable to be modified.
+ * \param oldval the old value.
+ * \param newval the new value.
+ * \returns SDL_TRUE if the atomic variable was set, SDL_FALSE otherwise.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.0.0.
+ *
+ * \sa SDL_GetAtomicU32
+ * \sa SDL_SetAtomicU32
+ */
+extern SDL_DECLSPEC SDL_bool SDLCALL SDL_CompareAndSwapAtomicU32(SDL_AtomicU32 *a, Uint32 oldval, Uint32 newval);
+
+/**
+ * Set an atomic variable to a value.
+ *
+ * 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!***
+ *
+ * \param a a pointer to an SDL_AtomicU32 variable to be modified.
+ * \param v the desired value.
+ * \returns the previous value of the atomic variable.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.0.0.
+ *
+ * \sa SDL_GetAtomicU32
+ */
+extern SDL_DECLSPEC Uint32 SDLCALL SDL_SetAtomicU32(SDL_AtomicU32 *a, Uint32 v);
+
+/**
+ * Get the value of an atomic variable.
+ *
+ * ***Note: If you don't know what this function is for, you shouldn't use
+ * it!***
+ *
+ * \param a a pointer to an SDL_AtomicU32 variable.
+ * \returns the current value of an atomic variable.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.0.0.
+ *
+ * \sa SDL_SetAtomicU32
+ */
+extern SDL_DECLSPEC Uint32 SDLCALL SDL_GetAtomicU32(SDL_AtomicU32 *a);
+
 /**
  * Set a pointer to a new value if it is currently an old value.
  *