From d0edf6877413750e507bf1d9149cd29080d4ae09 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Tue, 17 Sep 2024 03:27:11 -0700
Subject: [PATCH] Added Uint32 versions of the atomic functions
---
include/SDL3/SDL_atomic.h | 90 ++++++++++++++++++++++++++++++-
src/atomic/SDL_atomic.c | 85 ++++++++++++++++++++++++++++-
src/dynapi/SDL_dynapi.sym | 3 ++
src/dynapi/SDL_dynapi_overrides.h | 3 ++
src/dynapi/SDL_dynapi_procs.h | 3 ++
5 files changed, 180 insertions(+), 4 deletions(-)
diff --git a/include/SDL3/SDL_atomic.h b/include/SDL3/SDL_atomic.h
index f76bcbb43e7cf..3a8be356461de 100644
--- a/include/SDL3/SDL_atomic.h
+++ b/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.
*
diff --git a/src/atomic/SDL_atomic.c b/src/atomic/SDL_atomic.c
index 1eb1a90ca5b50..aceb237853390 100644
--- a/src/atomic/SDL_atomic.c
+++ b/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
diff --git a/src/dynapi/SDL_dynapi.sym b/src/dynapi/SDL_dynapi.sym
index 8545534fb6705..1b22f05440d34 100644
--- a/src/dynapi/SDL_dynapi.sym
+++ b/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;
diff --git a/src/dynapi/SDL_dynapi_overrides.h b/src/dynapi/SDL_dynapi_overrides.h
index b6e89d6ebc9ba..4b59a825aa97d 100644
--- a/src/dynapi/SDL_dynapi_overrides.h
+++ b/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
diff --git a/src/dynapi/SDL_dynapi_procs.h b/src/dynapi/SDL_dynapi_procs.h
index b32aa916965b1..6649326c6d996 100644
--- a/src/dynapi/SDL_dynapi_procs.h
+++ b/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)