Avoid duplicating code using a macro

5 files changed, 18 insertions, 54 deletions

diff --git a/Alc/ALu.c b/Alc/ALu.c
index db032057..dc979522 100644
--- a/Alc/ALu.c
+++ b/Alc/ALu.c
@@ -239,7 +239,6 @@ static ALboolean CalcListenerParams(ALCcontext *Context)
 {
     ALlistener *Listener = Context->Listener;
     ALfloat N[3], V[3], U[3], P[3];
-    struct ALlistenerProps *first;
     struct ALlistenerProps *props;
     aluVector vel;
 
@@ -288,24 +287,12 @@ static ALboolean CalcListenerParams(ALCcontext *Context)
     Listener->Params.SourceDistanceModel = ATOMIC_LOAD(&props->SourceDistanceModel, almemory_order_relaxed);
     Listener->Params.DistanceModel = ATOMIC_LOAD(&props->DistanceModel, almemory_order_relaxed);
 
-    /* WARNING: A livelock is theoretically possible if another thread keeps
-     * changing the freelist head without giving this a chance to actually swap
-     * in the old container (practically impossible with this little code,
-     * but...).
-     */
-    first = ATOMIC_LOAD(&Listener->FreeList, almemory_order_acquire);
-    do {
-        ATOMIC_STORE(&props->next, first, almemory_order_relaxed);
-    } while(ATOMIC_COMPARE_EXCHANGE_WEAK(struct ALlistenerProps*,
-            &Listener->FreeList, &first, props, almemory_order_acq_rel,
-            almemory_order_acquire) == 0);
-
+    ATOMIC_REPLACE_HEAD(struct ALlistenerProps*, &Listener->FreeList, props);
     return AL_TRUE;
 }
 
 static ALboolean CalcEffectSlotParams(ALeffectslot *slot, ALCdevice *device)
 {
-    struct ALeffectslotProps *first;
     struct ALeffectslotProps *props;
     ALeffectState *state;
 
@@ -337,18 +324,7 @@ static ALboolean CalcEffectSlotParams(ALeffectslot *slot, ALCdevice *device)
 
     V(state,update)(device, slot, &props->Props);
 
-    /* WARNING: A livelock is theoretically possible if another thread keeps
-     * changing the freelist head without giving this a chance to actually swap
-     * in the old container (practically impossible with this little code,
-     * but...).
-     */
-    first = ATOMIC_LOAD(&slot->FreeList, almemory_order_acquire);
-    do {
-        ATOMIC_STORE(&props->next, first, almemory_order_relaxed);
-    } while(ATOMIC_COMPARE_EXCHANGE_WEAK(struct ALeffectslotProps*,
-            &slot->FreeList, &first, props, almemory_order_acq_rel,
-            almemory_order_acquire) == 0);
-
+    ATOMIC_REPLACE_HEAD(struct ALeffectslotProps*, &slot->FreeList, props);
     return AL_TRUE;
 }
 
@@ -1301,7 +1277,6 @@ static void CalcSourceParams(ALvoice *voice, ALCcontext *context, ALboolean forc
 {
     ALsource *source = voice->Source;
     const ALbufferlistitem *BufferListItem;
-    struct ALsourceProps *first;
     struct ALsourceProps *props;
 
     props = ATOMIC_EXCHANGE(struct ALsourceProps*, &source->Update, NULL, almemory_order_acq_rel);
@@ -1311,17 +1286,7 @@ static void CalcSourceParams(ALvoice *voice, ALCcontext *context, ALboolean forc
     {
         voice->Props = *props;
 
-        /* WARNING: A livelock is theoretically possible if another thread
-         * keeps changing the freelist head without giving this a chance to
-         * actually swap in the old container (practically impossible with this
-         * little code, but...).
-         */
-        first = ATOMIC_LOAD(&source->FreeList, almemory_order_acquire);
-        do {
-            ATOMIC_STORE(&props->next, first, almemory_order_relaxed);
-        } while(ATOMIC_COMPARE_EXCHANGE_WEAK(struct ALsourceProps*,
-                &source->FreeList, &first, props, almemory_order_acq_rel,
-                almemory_order_acquire) == 0);
+        ATOMIC_REPLACE_HEAD(struct ALsourceProps*, &source->FreeList, props);
     }
 
     BufferListItem = ATOMIC_LOAD(&source->queue, almemory_order_relaxed);
diff --git a/OpenAL32/alAuxEffectSlot.c b/OpenAL32/alAuxEffectSlot.c
index a7bc0f32..e6b4ff68 100644
--- a/OpenAL32/alAuxEffectSlot.c
+++ b/OpenAL32/alAuxEffectSlot.c
@@ -671,11 +671,7 @@ void UpdateEffectSlotProps(ALeffectslot *slot)
         /* If there was an unused update container, put it back in the
          * freelist.
          */
-        struct ALeffectslotProps *first = ATOMIC_LOAD_SEQ(&slot->FreeList);
-        do {
-            ATOMIC_STORE(&props->next, first, almemory_order_relaxed);
-        } while(ATOMIC_COMPARE_EXCHANGE_WEAK_SEQ(struct ALeffectslotProps*,
-                &slot->FreeList, &first, props) == 0);
+        ATOMIC_REPLACE_HEAD(struct ALeffectslotProps*, &slot->FreeList, props);
     }
 
     if(oldstate)
diff --git a/OpenAL32/alListener.c b/OpenAL32/alListener.c
index f05c20d1..9c237e99 100644
--- a/OpenAL32/alListener.c
+++ b/OpenAL32/alListener.c
@@ -506,10 +506,6 @@ void UpdateListenerProps(ALCcontext *context)
         /* If there was an unused update container, put it back in the
          * freelist.
          */
-        struct ALlistenerProps *first = ATOMIC_LOAD_SEQ(&listener->FreeList);
-        do {
-            ATOMIC_STORE(&props->next, first, almemory_order_relaxed);
-        } while(ATOMIC_COMPARE_EXCHANGE_WEAK_SEQ(struct ALlistenerProps*,
-                &listener->FreeList, &first, props) == 0);
+        ATOMIC_REPLACE_HEAD(struct ALlistenerProps*, &listener->FreeList, props);
     }
 }
diff --git a/OpenAL32/alSource.c b/OpenAL32/alSource.c
index 9f60c545..e3d3cf1b 100644
--- a/OpenAL32/alSource.c
+++ b/OpenAL32/alSource.c
@@ -2913,12 +2913,7 @@ static void UpdateSourceProps(ALsource *source, ALuint num_sends)
         /* If there was an unused update container, put it back in the
          * freelist.
          */
-        struct ALsourceProps *first = ATOMIC_LOAD_SEQ(&source->FreeList);
-        do {
-            ATOMIC_STORE(&props->next, first, almemory_order_relaxed);
-        } while(ATOMIC_COMPARE_EXCHANGE_WEAK(struct ALsourceProps*,
-                &source->FreeList, &first, props, almemory_order_acq_rel,
-                almemory_order_acquire) == 0);
+        ATOMIC_REPLACE_HEAD(struct ALsourceProps*, &source->FreeList, props);
     }
 }
 
diff --git a/include/atomic.h b/include/atomic.h
index 4783defe..57609c33 100644
--- a/include/atomic.h
+++ b/include/atomic.h
@@ -373,6 +373,18 @@ inline uint DecrementRef(RefCount *ptr)
 { return ATOMIC_SUB_SEQ(ptr, 1)-1; }
 
 
+/* WARNING: A livelock is theoretically possible if another thread keeps
+ * changing the head without giving this a chance to actually swap in the new
+ * one (practically impossible with this little code, but...).
+ */
+#define ATOMIC_REPLACE_HEAD(T, _head, _entry) do {                            \
+    T _first = ATOMIC_LOAD(_head, almemory_order_acquire);                    \
+    do {                                                                      \
+        ATOMIC_STORE(&(_entry)->next, _first, almemory_order_relaxed);        \
+    } while(ATOMIC_COMPARE_EXCHANGE_WEAK(T, _head, &_first, _entry,           \
+            almemory_order_acq_rel, almemory_order_acquire) == 0);            \
+} while(0)
+
 #ifdef __cplusplus
 }
 #endif