Store the effect's output buffer in the effect state

Alc/ALc.c

@@ -2170,6 +2170,8 @@ static ALCenum UpdateDeviceParams(ALCdevice *device, const ALCint *attrList)
         {
             ALeffectslot *slot = context->EffectSlotMap.array[pos].value;
 
+            slot->EffectState->OutBuffer = device->Dry.Buffer;
+            slot->EffectState->OutChannels = device->Dry.NumChannels;
             if(V(slot->EffectState,deviceUpdate)(device) == AL_FALSE)
             {
                 UnlockUIntMapRead(&context->EffectSlotMap);
@@ -2217,8 +2219,11 @@ static ALCenum UpdateDeviceParams(ALCdevice *device, const ALCint *attrList)
     if(device->DefaultSlot)
     {
         ALeffectslot *slot = device->DefaultSlot;
+        ALeffectState *state = slot->EffectState;
 
-        if(V(slot->EffectState,deviceUpdate)(device) == AL_FALSE)
+        state->OutBuffer = device->Dry.Buffer;
+        state->OutChannels = device->Dry.NumChannels;
+        if(V(state,deviceUpdate)(device) == AL_FALSE)
         {
             V0(device->Backend,unlock)();
             RestoreFPUMode(&oldMode);

Alc/ALu.c

@@ -1417,8 +1417,8 @@ ALvoid aluMixData(ALCdevice *device, ALvoid *buffer, ALsizei size)
             {
                 const ALeffectslot *slot = VECTOR_ELEM(ctx->ActiveAuxSlots, i);
                 ALeffectState *state = slot->EffectState;
-                V(state,process)(SamplesToDo, slot->WetBuffer, device->Dry.Buffer,
-                                 device->Dry.NumChannels);
+                V(state,process)(SamplesToDo, slot->WetBuffer, state->OutBuffer,
+                                 state->OutChannels);
             }
 
             ctx = ctx->next;
@@ -1428,8 +1428,8 @@ ALvoid aluMixData(ALCdevice *device, ALvoid *buffer, ALsizei size)
         {
             const ALeffectslot *slot = device->DefaultSlot;
             ALeffectState *state = slot->EffectState;
-            V(state,process)(SamplesToDo, slot->WetBuffer, device->Dry.Buffer,
-                             device->Dry.NumChannels);
+            V(state,process)(SamplesToDo, slot->WetBuffer, state->OutBuffer,
+                             state->OutChannels);
         }
 
         /* Increment the clock time. Every second's worth of samples is
@@ -1503,7 +1503,7 @@ ALvoid aluMixData(ALCdevice *device, ALvoid *buffer, ALsizei size)
         if(buffer)
         {
             ALfloat (*OutBuffer)[BUFFERSIZE] = device->RealOut.Buffer;
-            ALuint OutChannels = device->RealOut.NumChannels;;
+            ALuint OutChannels = device->RealOut.NumChannels;
 
 #define WRITE(T, a, b, c, d) do {               \
     Write_##T((a), (b), (c), (d));              \

OpenAL32/Include/alAuxEffectSlot.h

@@ -15,6 +15,9 @@ struct ALeffectslot;
 
 typedef struct ALeffectState {
     const struct ALeffectStateVtable *vtbl;
+
+    ALfloat (*OutBuffer)[BUFFERSIZE];
+    ALuint OutChannels;
 } ALeffectState;
 
 struct ALeffectStateVtable {

OpenAL32/alAuxEffectSlot.c

@@ -464,6 +464,8 @@ ALenum InitializeEffect(ALCdevice *Device, ALeffectslot *EffectSlot, ALeffect *e
         SetMixerFPUMode(&oldMode);
 
         ALCdevice_Lock(Device);
+        State->OutBuffer = Device->Dry.Buffer;
+        State->OutChannels = Device->Dry.NumChannels;
         if(V(State,deviceUpdate)(Device) == AL_FALSE)
         {
             ALCdevice_Unlock(Device);