Make auxiliary effect slot count configurable

Alc/ALc.c

@@ -479,6 +479,8 @@ static ALvoid InitContext(ALCcontext *pContext)
     pContext->lNumStereoSources = 1;
     pContext->lNumMonoSources = pContext->Device->MaxNoOfSources - pContext->lNumStereoSources;
 
+    pContext->AuxiliaryEffectSlotMax = GetConfigValueInt(NULL, "slots", 4);
+
     pContext->ExtensionList = "AL_EXTX_buffer_sub_data AL_EXT_EXPONENT_DISTANCE AL_EXT_FLOAT32 AL_EXT_IMA4 AL_EXT_LINEAR_DISTANCE AL_EXT_MCFORMATS AL_EXT_OFFSET AL_EXTX_source_distance_model AL_LOKI_quadriphonic";
 
     level = GetConfigValueInt(NULL, "cf_level", 0);

OpenAL32/Include/alMain.h

@@ -194,6 +194,8 @@ struct ALCcontext_struct
 
     struct ALeffectslot *AuxiliaryEffectSlot;
     ALuint               AuxiliaryEffectSlotCount;
+    // Maximum number of slots that can be created
+    ALuint               AuxiliaryEffectSlotMax;
 
     ALenum      LastError;
     ALboolean   InUse;

OpenAL32/alAuxEffectSlot.c

@@ -50,8 +50,7 @@ ALvoid AL_APIENTRY alGenAuxiliaryEffectSlots(ALsizei n, ALuint *effectslots)
 
     if (n > 0)
     {
-        /* NOTE: We only support one slot currently */
-        if(n == 1 && Context->AuxiliaryEffectSlotCount == 0)
+        if(Context->AuxiliaryEffectSlotCount+n <= Context->AuxiliaryEffectSlotMax)
         {
             // Check that enough memory has been allocted in the 'effectslots' array for n Effect Slots
             if (!IsBadWritePtr((void*)effectslots, n * sizeof(ALuint)))

alsoftrc.sample

@@ -67,6 +67,11 @@ excludefx =  # Sets which effects to exclude, preventing apps from using them.
              # reverb
              # Default is empty (all available effects enabled)
 
+slots = 4  # Sets the maximum number of Auxiliary Effect Slots an app can
+           # create. A slot can use a non-negligible amount of CPU time if an
+           # effect is set on it even if no sources are feeding it, so this may
+           # help when apps use more than the system can handle. Default is 4
+
 layout_STEREO =  # Sets the speaker layout when using stereo output. Values are
                  # specified in degrees, where 0 is straight in front, negative
                  # goes left, and positive goes right. The values must define a