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.
  *

src/atomic/SDL_atomic.c

@@ -128,12 +128,13 @@ SDL_bool SDL_CompareAndSwapAtomicInt(SDL_AtomicInt *a, int oldval, int newval)
     SDL_COMPILE_TIME_ASSERT(atomic_cas, sizeof(long) == sizeof(a->value));
     return _InterlockedCompareExchange((long *)&a->value, (long)newval, (long)oldval) == (long)oldval;
 #elif defined(HAVE_WATCOM_ATOMICS)
-    return _SDL_cmpxchg_watcom(&a->value, newval, oldval);
+    return _SDL_cmpxchg_watcom((volatile int *)&a->value, newval, oldval);
 #elif defined(HAVE_GCC_ATOMICS)
     return __sync_bool_compare_and_swap(&a->value, oldval, newval);
 #elif defined(SDL_PLATFORM_MACOS) // this is deprecated in 10.12 sdk; favor gcc atomics.
     return OSAtomicCompareAndSwap32Barrier(oldval, newval, &a->value);
 #elif defined(SDL_PLATFORM_SOLARIS)
+    SDL_COMPILE_TIME_ASSERT(atomic_cas, sizeof(uint_t) == sizeof(a->value));
     return ((int)atomic_cas_uint((volatile uint_t *)&a->value, (uint_t)oldval, (uint_t)newval) == oldval);
 #elif defined(EMULATE_CAS)
     bool result = false;
@@ -151,6 +152,37 @@ SDL_bool SDL_CompareAndSwapAtomicInt(SDL_AtomicInt *a, int oldval, int newval)
 #endif
 }
 
+SDL_bool SDL_CompareAndSwapAtomicU32(SDL_AtomicU32 *a, Uint32 oldval, Uint32 newval)
+{
+#ifdef HAVE_MSC_ATOMICS
+    SDL_COMPILE_TIME_ASSERT(atomic_cas, sizeof(long) == sizeof(a->value));
+    return _InterlockedCompareExchange((long *)&a->value, (long)newval, (long)oldval) == (long)oldval;
+#elif defined(HAVE_WATCOM_ATOMICS)
+    SDL_COMPILE_TIME_ASSERT(atomic_cas, sizeof(int) == sizeof(a->value));
+    return _SDL_cmpxchg_watcom((volatile int *)&a->value, (int)newval, (int)oldval);
+#elif defined(HAVE_GCC_ATOMICS)
+    return __sync_bool_compare_and_swap(&a->value, oldval, newval);
+#elif defined(SDL_PLATFORM_MACOS) // this is deprecated in 10.12 sdk; favor gcc atomics.
+    return OSAtomicCompareAndSwap32Barrier((int32_t)oldval, (int32_t)newval, (int32_t*)&a->value);
+#elif defined(SDL_PLATFORM_SOLARIS)
+    SDL_COMPILE_TIME_ASSERT(atomic_cas, sizeof(uint_t) == sizeof(a->value));
+    return ((Uint32)atomic_cas_uint((volatile uint_t *)&a->value, (uint_t)oldval, (uint_t)newval) == oldval);
+#elif defined(EMULATE_CAS)
+    bool result = false;
+
+    enterLock(a);
+    if (a->value == oldval) {
+        a->value = newval;
+        result = true;
+    }
+    leaveLock(a);
+
+    return result;
+#else
+#error Please define your platform.
+#endif
+}
+
 SDL_bool SDL_CompareAndSwapAtomicPointer(void **a, void *oldval, void *newval)
 {
 #ifdef HAVE_MSC_ATOMICS
@@ -191,6 +223,7 @@ int SDL_SetAtomicInt(SDL_AtomicInt *a, int v)
 #elif defined(HAVE_GCC_ATOMICS)
     return __sync_lock_test_and_set(&a->value, v);
 #elif defined(SDL_PLATFORM_SOLARIS)
+    SDL_COMPILE_TIME_ASSERT(atomic_set, sizeof(uint_t) == sizeof(a->value));
     return (int)atomic_swap_uint((volatile uint_t *)&a->value, v);
 #else
     int value;
@@ -201,6 +234,27 @@ int SDL_SetAtomicInt(SDL_AtomicInt *a, int v)
 #endif
 }
 
+Uint32 SDL_SetAtomicU32(SDL_AtomicU32 *a, Uint32 v)
+{
+#ifdef HAVE_MSC_ATOMICS
+    SDL_COMPILE_TIME_ASSERT(atomic_set, sizeof(long) == sizeof(a->value));
+    return _InterlockedExchange((long *)&a->value, v);
+#elif defined(HAVE_WATCOM_ATOMICS)
+    return _SDL_xchg_watcom(&a->value, v);
+#elif defined(HAVE_GCC_ATOMICS)
+    return __sync_lock_test_and_set(&a->value, v);
+#elif defined(SDL_PLATFORM_SOLARIS)
+    SDL_COMPILE_TIME_ASSERT(atomic_set, sizeof(uint_t) == sizeof(a->value));
+    return (Uint32)atomic_swap_uint((volatile uint_t *)&a->value, v);
+#else
+    Uint32 value;
+    do {
+        value = a->value;
+    } while (!SDL_CompareAndSwapAtomicU32(a, value, v));
+    return value;
+#endif
+}
+
 void *SDL_SetAtomicPointer(void **a, void *v)
 {
 #ifdef HAVE_MSC_ATOMICS
@@ -226,7 +280,8 @@ int SDL_AddAtomicInt(SDL_AtomicInt *a, int v)
     SDL_COMPILE_TIME_ASSERT(atomic_add, sizeof(long) == sizeof(a->value));
     return _InterlockedExchangeAdd((long *)&a->value, v);
 #elif defined(HAVE_WATCOM_ATOMICS)
-    return _SDL_xadd_watcom(&a->value, v);
+    SDL_COMPILE_TIME_ASSERT(atomic_add, sizeof(int) == sizeof(a->value));
+    return _SDL_xadd_watcom((volatile int *)&a->value, v);
 #elif defined(HAVE_GCC_ATOMICS)
     return __sync_fetch_and_add(&a->value, v);
 #elif defined(SDL_PLATFORM_SOLARIS)
@@ -267,6 +322,32 @@ int SDL_GetAtomicInt(SDL_AtomicInt *a)
 #endif
 }
 
+Uint32 SDL_GetAtomicU32(SDL_AtomicU32 *a)
+{
+#ifdef HAVE_ATOMIC_LOAD_N
+    return __atomic_load_n(&a->value, __ATOMIC_SEQ_CST);
+#elif defined(HAVE_MSC_ATOMICS)
+    SDL_COMPILE_TIME_ASSERT(atomic_get, sizeof(long) == sizeof(a->value));
+    return (Uint32)_InterlockedOr((long *)&a->value, 0);
+#elif defined(HAVE_WATCOM_ATOMICS)
+    SDL_COMPILE_TIME_ASSERT(atomic_get, sizeof(int) == sizeof(a->value));
+    return (Uint32)_SDL_xadd_watcom((volatile int *)&a->value, 0);
+#elif defined(HAVE_GCC_ATOMICS)
+    return __sync_or_and_fetch(&a->value, 0);
+#elif defined(SDL_PLATFORM_MACOS) // this is deprecated in 10.12 sdk; favor gcc atomics.
+    return OSAtomicOr32Barrier(0, (volatile uint32_t *)&a->value);
+#elif defined(SDL_PLATFORM_SOLARIS)
+    SDL_COMPILE_TIME_ASSERT(atomic_get, sizeof(uint_t) == sizeof(a->value));
+    return (Uint32)atomic_or_uint_nv((volatile uint_t *)&a->value, 0);
+#else
+    Uint32 value;
+    do {
+        value = a->value;
+    } while (!SDL_CompareAndSwapAtomicU32(a, value, value));
+    return value;
+#endif
+}
+
 void *SDL_GetAtomicPointer(void **a)
 {
 #ifdef HAVE_ATOMIC_LOAD_N

src/dynapi/SDL_dynapi.sym

@@ -63,6 +63,7 @@ SDL3_0.0.0 {
     SDL_CloseStorage;
     SDL_CompareAndSwapAtomicInt;
     SDL_CompareAndSwapAtomicPointer;
+    SDL_CompareAndSwapAtomicU32;
     SDL_ComposeCustomBlendMode;
     SDL_ConvertAudioSamples;
     SDL_ConvertEventToRenderCoordinates;
@@ -215,6 +216,7 @@ SDL3_0.0.0 {
     SDL_GetAssertionReport;
     SDL_GetAtomicInt;
     SDL_GetAtomicPointer;
+    SDL_GetAtomicU32;
     SDL_GetAudioDeviceChannelMap;
     SDL_GetAudioDeviceFormat;
     SDL_GetAudioDeviceGain;
@@ -780,6 +782,7 @@ SDL3_0.0.0 {
     SDL_SetAssertionHandler;
     SDL_SetAtomicInt;
     SDL_SetAtomicPointer;
+    SDL_SetAtomicU32;
     SDL_SetAudioDeviceGain;
     SDL_SetAudioPostmixCallback;
     SDL_SetAudioStreamFormat;

src/dynapi/SDL_dynapi_overrides.h

@@ -88,6 +88,7 @@
 #define SDL_CloseStorage SDL_CloseStorage_REAL
 #define SDL_CompareAndSwapAtomicInt SDL_CompareAndSwapAtomicInt_REAL
 #define SDL_CompareAndSwapAtomicPointer SDL_CompareAndSwapAtomicPointer_REAL
+#define SDL_CompareAndSwapAtomicU32 SDL_CompareAndSwapAtomicU32_REAL
 #define SDL_ComposeCustomBlendMode SDL_ComposeCustomBlendMode_REAL
 #define SDL_ConvertAudioSamples SDL_ConvertAudioSamples_REAL
 #define SDL_ConvertEventToRenderCoordinates SDL_ConvertEventToRenderCoordinates_REAL
@@ -240,6 +241,7 @@
 #define SDL_GetAssertionReport SDL_GetAssertionReport_REAL
 #define SDL_GetAtomicInt SDL_GetAtomicInt_REAL
 #define SDL_GetAtomicPointer SDL_GetAtomicPointer_REAL
+#define SDL_GetAtomicU32 SDL_GetAtomicU32_REAL
 #define SDL_GetAudioDeviceChannelMap SDL_GetAudioDeviceChannelMap_REAL
 #define SDL_GetAudioDeviceFormat SDL_GetAudioDeviceFormat_REAL
 #define SDL_GetAudioDeviceGain SDL_GetAudioDeviceGain_REAL
@@ -805,6 +807,7 @@
 #define SDL_SetAssertionHandler SDL_SetAssertionHandler_REAL
 #define SDL_SetAtomicInt SDL_SetAtomicInt_REAL
 #define SDL_SetAtomicPointer SDL_SetAtomicPointer_REAL
+#define SDL_SetAtomicU32 SDL_SetAtomicU32_REAL
 #define SDL_SetAudioDeviceGain SDL_SetAudioDeviceGain_REAL
 #define SDL_SetAudioPostmixCallback SDL_SetAudioPostmixCallback_REAL
 #define SDL_SetAudioStreamFormat SDL_SetAudioStreamFormat_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -109,6 +109,7 @@ SDL_DYNAPI_PROC(void,SDL_CloseSensor,(SDL_Sensor *a),(a),)
 SDL_DYNAPI_PROC(SDL_bool,SDL_CloseStorage,(SDL_Storage *a),(a),return)
 SDL_DYNAPI_PROC(SDL_bool,SDL_CompareAndSwapAtomicInt,(SDL_AtomicInt *a, int b, int c),(a,b,c),return)
 SDL_DYNAPI_PROC(SDL_bool,SDL_CompareAndSwapAtomicPointer,(void **a, void *b, void *c),(a,b,c),return)
+SDL_DYNAPI_PROC(SDL_bool,SDL_CompareAndSwapAtomicU32,(SDL_AtomicU32 *a, Uint32 b, Uint32 c),(a,b,c),return)
 SDL_DYNAPI_PROC(SDL_BlendMode,SDL_ComposeCustomBlendMode,(SDL_BlendFactor a, SDL_BlendFactor b, SDL_BlendOperation c, SDL_BlendFactor d, SDL_BlendFactor e, SDL_BlendOperation f),(a,b,c,d,e,f),return)
 SDL_DYNAPI_PROC(SDL_bool,SDL_ConvertAudioSamples,(const SDL_AudioSpec *a, const Uint8 *b, int c, const SDL_AudioSpec *d, Uint8 **e, int *f),(a,b,c,d,e,f),return)
 SDL_DYNAPI_PROC(SDL_bool,SDL_ConvertEventToRenderCoordinates,(SDL_Renderer *a, SDL_Event *b),(a,b),return)
@@ -261,6 +262,7 @@ SDL_DYNAPI_PROC(SDL_AssertionHandler,SDL_GetAssertionHandler,(void **a),(a),retu
 SDL_DYNAPI_PROC(const SDL_AssertData*,SDL_GetAssertionReport,(void),(),return)
 SDL_DYNAPI_PROC(int,SDL_GetAtomicInt,(SDL_AtomicInt *a),(a),return)
 SDL_DYNAPI_PROC(void*,SDL_GetAtomicPointer,(void **a),(a),return)
+SDL_DYNAPI_PROC(Uint32,SDL_GetAtomicU32,(SDL_AtomicU32 *a),(a),return)
 SDL_DYNAPI_PROC(int*,SDL_GetAudioDeviceChannelMap,(SDL_AudioDeviceID a, int *b),(a,b),return)
 SDL_DYNAPI_PROC(SDL_bool,SDL_GetAudioDeviceFormat,(SDL_AudioDeviceID a, SDL_AudioSpec *b, int *c),(a,b,c),return)
 SDL_DYNAPI_PROC(float,SDL_GetAudioDeviceGain,(SDL_AudioDeviceID a),(a),return)
@@ -816,6 +818,7 @@ SDL_DYNAPI_PROC(SDL_bool,SDL_SetAppMetadataProperty,(const char *a, const char *
 SDL_DYNAPI_PROC(void,SDL_SetAssertionHandler,(SDL_AssertionHandler a, void *b),(a,b),)
 SDL_DYNAPI_PROC(int,SDL_SetAtomicInt,(SDL_AtomicInt *a, int b),(a,b),return)
 SDL_DYNAPI_PROC(void*,SDL_SetAtomicPointer,(void **a, void *b),(a,b),return)
+SDL_DYNAPI_PROC(Uint32,SDL_SetAtomicU32,(SDL_AtomicU32 *a, Uint32 b),(a,b),return)
 SDL_DYNAPI_PROC(SDL_bool,SDL_SetAudioDeviceGain,(SDL_AudioDeviceID a, float b),(a,b),return)
 SDL_DYNAPI_PROC(SDL_bool,SDL_SetAudioPostmixCallback,(SDL_AudioDeviceID a, SDL_AudioPostmixCallback b, void *c),(a,b,c),return)
 SDL_DYNAPI_PROC(SDL_bool,SDL_SetAudioStreamFormat,(SDL_AudioStream *a, const SDL_AudioSpec *b, const SDL_AudioSpec *c),(a,b,c),return)