/**
 * OpenAL cross platform audio library
 * Copyright (C) 1999-2007 by authors.
 * This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the
 *  Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 * Or go to http://www.gnu.org/copyleft/lgpl.html
 */

#include "config.h"

#include <cstdlib>
#include <cmath>

#include <thread>
#include <algorithm>

#include "AL/al.h"
#include "AL/alc.h"

#include "alMain.h"
#include "alcontext.h"
#include "alAuxEffectSlot.h"
#include "alError.h"
#include "alListener.h"
#include "alSource.h"

#include "fpu_modes.h"
#include "almalloc.h"


namespace {

inline ALeffectslot *LookupEffectSlot(ALCcontext *context, ALuint id) noexcept
{
    ALuint lidx = (id-1) >> 6;
    ALsizei slidx = (id-1) & 0x3f;

    if(UNLIKELY(lidx >= context->EffectSlotList.size()))
        return nullptr;
    EffectSlotSubList &sublist{context->EffectSlotList[lidx]};
    if(UNLIKELY(sublist.FreeMask & (1_u64 << slidx)))
        return nullptr;
    return sublist.EffectSlots + slidx;
}

inline ALeffect *LookupEffect(ALCdevice *device, ALuint id) noexcept
{
    ALuint lidx = (id-1) >> 6;
    ALsizei slidx = (id-1) & 0x3f;

    if(UNLIKELY(lidx >= device->EffectList.size()))
        return nullptr;
    EffectSubList &sublist = device->EffectList[lidx];
    if(UNLIKELY(sublist.FreeMask & (1_u64 << slidx)))
        return nullptr;
    return sublist.Effects + slidx;
}


void AddActiveEffectSlots(const ALuint *slotids, ALsizei count, ALCcontext *context)
{
    if(count < 1) return;
    ALeffectslotArray *curarray{context->ActiveAuxSlots.load(std::memory_order_acquire)};
    size_t newcount{curarray->size() + count};

    /* Insert the new effect slots into the head of the array, followed by the
     * existing ones.
     */
    ALeffectslotArray *newarray = ALeffectslot::CreatePtrArray(newcount);
    auto slotiter = std::transform(slotids, slotids+count, newarray->begin(),
        [context](ALuint id) noexcept -> ALeffectslot*
        { return LookupEffectSlot(context, id); }
    );
    std::copy(curarray->begin(), curarray->end(), slotiter);

    /* Remove any duplicates (first instance of each will be kept). */
    auto last = newarray->end();
    for(auto start=newarray->begin()+1;;)
    {
        last = std::remove(start, last, *(start-1));
        if(start == last) break;
        ++start;
    }
    newcount = static_cast<size_t>(std::distance(newarray->begin(), last));

    /* Reallocate newarray if the new size ended up smaller from duplicate
     * removal.
     */
    if(UNLIKELY(newcount < newarray->size()))
    {
        curarray = newarray;
        newarray = ALeffectslot::CreatePtrArray(newcount);
        std::copy_n(curarray->begin(), newcount, newarray->begin());
        delete curarray;
        curarray = nullptr;
    }

    curarray = context->ActiveAuxSlots.exchange(newarray, std::memory_order_acq_rel);
    ALCdevice *device{context->Device};
    while((device->MixCount.load(std::memory_order_acquire)&1))
        std::this_thread::yield();
    delete curarray;
}

void RemoveActiveEffectSlots(const ALuint *slotids, ALsizei count, ALCcontext *context)
{
    if(count < 1) return;
    ALeffectslotArray *curarray{context->ActiveAuxSlots.load(std::memory_order_acquire)};

    /* Don't shrink the allocated array size since we don't know how many (if
     * any) of the effect slots to remove are in the array.
     */
    ALeffectslotArray *newarray = ALeffectslot::CreatePtrArray(curarray->size());

    /* Copy each element in curarray to newarray whose ID is not in slotids. */
    const ALuint *slotids_end{slotids + count};
    auto slotiter = std::copy_if(curarray->begin(), curarray->end(), newarray->begin(),
        [slotids, slotids_end](const ALeffectslot *slot) -> bool
        { return std::find(slotids, slotids_end, slot->id) == slotids_end; }
    );

    /* Reallocate with the new size. */
    auto newsize = static_cast<size_t>(std::distance(newarray->begin(), slotiter));
    if(LIKELY(newsize != newarray->size()))
    {
        curarray = newarray;
        newarray = ALeffectslot::CreatePtrArray(newsize);
        std::copy_n(curarray->begin(), newsize, newarray->begin());

        delete curarray;
        curarray = nullptr;
    }

    curarray = context->ActiveAuxSlots.exchange(newarray, std::memory_order_acq_rel);
    ALCdevice *device{context->Device};
    while((device->MixCount.load(std::memory_order_acquire)&1))
        std::this_thread::yield();
    delete curarray;
}


ALeffectslot *AllocEffectSlot(ALCcontext *context)
{
    ALCdevice *device{context->Device};
    std::lock_guard<std::mutex> _{context->EffectSlotLock};
    if(context->NumEffectSlots >= device->AuxiliaryEffectSlotMax)
    {
        alSetError(context, AL_OUT_OF_MEMORY, "Exceeding %u effect slot limit",
            device->AuxiliaryEffectSlotMax);
        return nullptr;
    }
    auto sublist = std::find_if(context->EffectSlotList.begin(), context->EffectSlotList.end(),
        [](const EffectSlotSubList &entry) noexcept -> bool
        { return entry.FreeMask != 0; }
    );
    auto lidx = static_cast<ALsizei>(std::distance(context->EffectSlotList.begin(), sublist));
    ALeffectslot *slot;
    ALsizei slidx;
    if(LIKELY(sublist != context->EffectSlotList.end()))
    {
        slidx = CTZ64(sublist->FreeMask);
        slot = sublist->EffectSlots + slidx;
    }
    else
    {
        /* Don't allocate so many list entries that the 32-bit ID could
         * overflow...
         */
        if(UNLIKELY(context->EffectSlotList.size() >= 1<<25))
        {
            alSetError(context, AL_OUT_OF_MEMORY, "Too many effect slots allocated");
            return nullptr;
        }
        context->EffectSlotList.emplace_back();
        sublist = context->EffectSlotList.end() - 1;

        sublist->FreeMask = ~0_u64;
        sublist->EffectSlots = static_cast<ALeffectslot*>(al_calloc(16, sizeof(ALeffectslot)*64));
        if(UNLIKELY(!sublist->EffectSlots))
        {
            context->EffectSlotList.pop_back();
            alSetError(context, AL_OUT_OF_MEMORY, "Failed to allocate effect slot batch");
            return nullptr;
        }

        slidx = 0;
        slot = sublist->EffectSlots + slidx;
    }

    slot = new (slot) ALeffectslot{};
    ALenum err{InitEffectSlot(slot)};
    if(err != AL_NO_ERROR)
    {
        slot->~ALeffectslot();
        alSetError(context, err, "Effect slot object initialization failed");
        return nullptr;
    }
    aluInitEffectPanning(slot, device);

    /* Add 1 to avoid source ID 0. */
    slot->id = ((lidx<<6) | slidx) + 1;

    context->NumEffectSlots += 1;
    sublist->FreeMask &= ~(1_u64 << slidx);

    return slot;
}

void FreeEffectSlot(ALCcontext *context, ALeffectslot *slot)
{
    ALuint id = slot->id - 1;
    ALsizei lidx = id >> 6;
    ALsizei slidx = id & 0x3f;

    slot->~ALeffectslot();

    context->EffectSlotList[lidx].FreeMask |= 1_u64 << slidx;
    context->NumEffectSlots--;
}


#define DO_UPDATEPROPS() do {                                                 \
    if(!context->DeferUpdates.load(std::memory_order_acquire))                \
        UpdateEffectSlotProps(slot, context.get());                           \
    else                                                                      \
        slot->PropsClean.clear(std::memory_order_release);                    \
} while(0)

} // namespace

ALeffectslotArray *ALeffectslot::CreatePtrArray(size_t count) noexcept
{
    /* Allocate space for twice as many pointers, so the mixer has scratch
     * space to store a sorted list during mixing.
     */
    void *ptr{al_calloc(DEF_ALIGN, ALeffectslotArray::Sizeof(count*2))};
    return new (ptr) ALeffectslotArray{count};
}


AL_API ALvoid AL_APIENTRY alGenAuxiliaryEffectSlots(ALsizei n, ALuint *effectslots)
{
    ContextRef context{GetContextRef()};
    if(UNLIKELY(!context)) return;

    if(n < 0)
        SETERR_RETURN(context.get(), AL_INVALID_VALUE,, "Generating %d effect slots", n);
    if(n == 0) return;

    if(n == 1)
    {
        ALeffectslot *slot{AllocEffectSlot(context.get())};
        if(!slot) return;
        effectslots[0] = slot->id;
    }
    else
    {
        auto tempids = al::vector<ALuint>(n);
        auto alloc_end = std::find_if_not(tempids.begin(), tempids.end(),
            [&context](ALuint &id) -> bool
            {
                ALeffectslot *slot{AllocEffectSlot(context.get())};
                if(!slot) return false;
                id = slot->id;
                return true;
            }
        );
        if(alloc_end != tempids.end())
        {
            auto count = static_cast<ALsizei>(std::distance(tempids.begin(), alloc_end));
            alDeleteAuxiliaryEffectSlots(count, tempids.data());
            return;
        }

        std::copy(tempids.cbegin(), tempids.cend(), effectslots);
    }

    std::unique_lock<std::mutex> slotlock{context->EffectSlotLock};
    AddActiveEffectSlots(effectslots, n, context.get());
}

AL_API ALvoid AL_APIENTRY alDeleteAuxiliaryEffectSlots(ALsizei n, const ALuint *effectslots)
{
    ContextRef context{GetContextRef()};
    if(UNLIKELY(!context)) return;

    if(n < 0)
        SETERR_RETURN(context.get(), AL_INVALID_VALUE,, "Deleting %d effect slots", n);
    if(n == 0) return;

    std::lock_guard<std::mutex> _{context->EffectSlotLock};
    auto effectslots_end = effectslots + n;
    auto bad_slot = std::find_if(effectslots, effectslots_end,
        [&context](ALuint id) -> bool
        {
            ALeffectslot *slot{LookupEffectSlot(context.get(), id)};
            if(!slot)
            {
                alSetError(context.get(), AL_INVALID_NAME, "Invalid effect slot ID %u", id);
                return true;
            }
            if(ReadRef(&slot->ref) != 0)
            {
                alSetError(context.get(), AL_INVALID_NAME, "Deleting in-use effect slot %u", id);
                return true;
            }
            return false;
        }
    );
    if(bad_slot != effectslots_end)
        return;

    // All effectslots are valid, remove and delete them
    RemoveActiveEffectSlots(effectslots, n, context.get());
    std::for_each(effectslots, effectslots_end,
        [&context](ALuint sid) -> void
        {
            ALeffectslot *slot{LookupEffectSlot(context.get(), sid)};
            if(slot) FreeEffectSlot(context.get(), slot);
        }
    );
}

AL_API ALboolean AL_APIENTRY alIsAuxiliaryEffectSlot(ALuint effectslot)
{
    ContextRef context{GetContextRef()};
    if(LIKELY(context))
    {
        std::lock_guard<std::mutex> _{context->EffectSlotLock};
        if(LookupEffectSlot(context.get(), effectslot) != nullptr)
            return AL_TRUE;
    }
    return AL_FALSE;
}

AL_API ALvoid AL_APIENTRY alAuxiliaryEffectSloti(ALuint effectslot, ALenum param, ALint value)
{
    ContextRef context{GetContextRef()};
    if(UNLIKELY(!context)) return;

    std::lock_guard<std::mutex> _{context->PropLock};
    std::lock_guard<std::mutex> __{context->EffectSlotLock};
    ALeffectslot *slot = LookupEffectSlot(context.get(), effectslot);
    if(UNLIKELY(!slot))
        SETERR_RETURN(context.get(), AL_INVALID_NAME,, "Invalid effect slot ID %u", effectslot);

    ALeffectslot *target{};
    ALCdevice *device{};
    ALenum err{};
    switch(param)
    {
    case AL_EFFECTSLOT_EFFECT:
        device = context->Device;

        { std::lock_guard<std::mutex> ___{device->EffectLock};
            ALeffect *effect{value ? LookupEffect(device, value) : nullptr};
            if(!(value == 0 || effect != nullptr))
                SETERR_RETURN(context.get(), AL_INVALID_VALUE,, "Invalid effect ID %u", value);
            err = InitializeEffect(context.get(), slot, effect);
        }
        if(err != AL_NO_ERROR)
        {
            alSetError(context.get(), err, "Effect initialization failed");
            return;
        }
        break;

    case AL_EFFECTSLOT_AUXILIARY_SEND_AUTO:
        if(!(value == AL_TRUE || value == AL_FALSE))
            SETERR_RETURN(context.get(), AL_INVALID_VALUE,,
                          "Effect slot auxiliary send auto out of range");
        slot->AuxSendAuto = value;
        break;

    case AL_EFFECTSLOT_TARGET_SOFT:
        target = (value ? LookupEffectSlot(context.get(), value) : nullptr);
        if(value && !target)
            SETERR_RETURN(context.get(), AL_INVALID_VALUE,, "Invalid effect slot target ID");
        if(target)
        {
            ALeffectslot *checker{target};
            while(checker && checker != slot)
                checker = checker->Target;
            if(checker)
                SETERR_RETURN(context.get(), AL_INVALID_OPERATION,,
                    "Setting target of effect slot ID %u to %u creates circular chain", slot->id,
                    target->id);
        }

        if(ALeffectslot *oldtarget{slot->Target})
        {
            /* We must force an update if there was an existing effect slot
             * target, in case it's about to be deleted.
             */
            if(target) IncrementRef(&target->ref);
            DecrementRef(&oldtarget->ref);
            slot->Target = target;
            UpdateEffectSlotProps(slot, context.get());
            return;
        }

        if(target) IncrementRef(&target->ref);
        slot->Target = target;
        break;

    default:
        SETERR_RETURN(context.get(), AL_INVALID_ENUM,,
                      "Invalid effect slot integer property 0x%04x", param);
    }
    DO_UPDATEPROPS();
}

AL_API ALvoid AL_APIENTRY alAuxiliaryEffectSlotiv(ALuint effectslot, ALenum param, const ALint *values)
{
    switch(param)
    {
    case AL_EFFECTSLOT_EFFECT:
    case AL_EFFECTSLOT_AUXILIARY_SEND_AUTO:
    case AL_EFFECTSLOT_TARGET_SOFT:
        alAuxiliaryEffectSloti(effectslot, param, values[0]);
        return;
    }

    ContextRef context{GetContextRef()};
    if(UNLIKELY(!context)) return;

    std::lock_guard<std::mutex> _{context->EffectSlotLock};
    ALeffectslot *slot = LookupEffectSlot(context.get(), effectslot);
    if(UNLIKELY(!slot))
        SETERR_RETURN(context.get(), AL_INVALID_NAME,, "Invalid effect slot ID %u", effectslot);

    switch(param)
    {
    default:
        SETERR_RETURN(context.get(), AL_INVALID_ENUM,,
                      "Invalid effect slot integer-vector property 0x%04x", param);
    }
}

AL_API ALvoid AL_APIENTRY alAuxiliaryEffectSlotf(ALuint effectslot, ALenum param, ALfloat value)
{
    ContextRef context{GetContextRef()};
    if(UNLIKELY(!context)) return;

    std::lock_guard<std::mutex> _{context->PropLock};
    std::lock_guard<std::mutex> __{context->EffectSlotLock};
    ALeffectslot *slot = LookupEffectSlot(context.get(), effectslot);
    if(UNLIKELY(!slot))
        SETERR_RETURN(context.get(), AL_INVALID_NAME,, "Invalid effect slot ID %u", effectslot);

    switch(param)
    {
    case AL_EFFECTSLOT_GAIN:
        if(!(value >= 0.0f && value <= 1.0f))
            SETERR_RETURN(context.get(), AL_INVALID_VALUE,, "Effect slot gain out of range");
        slot->Gain = value;
        break;

    default:
        SETERR_RETURN(context.get(), AL_INVALID_ENUM,, "Invalid effect slot float property 0x%04x",
                      param);
    }
    DO_UPDATEPROPS();
}

AL_API ALvoid AL_APIENTRY alAuxiliaryEffectSlotfv(ALuint effectslot, ALenum param, const ALfloat *values)
{
    switch(param)
    {
    case AL_EFFECTSLOT_GAIN:
        alAuxiliaryEffectSlotf(effectslot, param, values[0]);
        return;
    }

    ContextRef context{GetContextRef()};
    if(UNLIKELY(!context)) return;

    std::lock_guard<std::mutex> _{context->EffectSlotLock};
    ALeffectslot *slot = LookupEffectSlot(context.get(), effectslot);
    if(UNLIKELY(!slot))
        SETERR_RETURN(context.get(), AL_INVALID_NAME,, "Invalid effect slot ID %u", effectslot);

    switch(param)
    {
    default:
        SETERR_RETURN(context.get(), AL_INVALID_ENUM,,
                      "Invalid effect slot float-vector property 0x%04x", param);
    }
}

AL_API ALvoid AL_APIENTRY alGetAuxiliaryEffectSloti(ALuint effectslot, ALenum param, ALint *value)
{
    ContextRef context{GetContextRef()};
    if(UNLIKELY(!context)) return;

    std::lock_guard<std::mutex> _{context->EffectSlotLock};
    ALeffectslot *slot = LookupEffectSlot(context.get(), effectslot);
    if(UNLIKELY(!slot))
        SETERR_RETURN(context.get(), AL_INVALID_NAME,, "Invalid effect slot ID %u", effectslot);

    switch(param)
    {
    case AL_EFFECTSLOT_AUXILIARY_SEND_AUTO:
        *value = slot->AuxSendAuto;
        break;

    case AL_EFFECTSLOT_TARGET_SOFT:
        *value = slot->Target ? slot->Target->id : 0;
        break;

    default:
        SETERR_RETURN(context.get(), AL_INVALID_ENUM,,
                      "Invalid effect slot integer property 0x%04x", param);
    }
}

AL_API ALvoid AL_APIENTRY alGetAuxiliaryEffectSlotiv(ALuint effectslot, ALenum param, ALint *values)
{
    switch(param)
    {
    case AL_EFFECTSLOT_EFFECT:
    case AL_EFFECTSLOT_AUXILIARY_SEND_AUTO:
    case AL_EFFECTSLOT_TARGET_SOFT:
        alGetAuxiliaryEffectSloti(effectslot, param, values);
        return;
    }

    ContextRef context{GetContextRef()};
    if(UNLIKELY(!context)) return;

    std::lock_guard<std::mutex> _{context->EffectSlotLock};
    ALeffectslot *slot = LookupEffectSlot(context.get(), effectslot);
    if(UNLIKELY(!slot))
        SETERR_RETURN(context.get(), AL_INVALID_NAME,, "Invalid effect slot ID %u", effectslot);

    switch(param)
    {
    default:
        SETERR_RETURN(context.get(), AL_INVALID_ENUM,,
                      "Invalid effect slot integer-vector property 0x%04x", param);
    }
}

AL_API ALvoid AL_APIENTRY alGetAuxiliaryEffectSlotf(ALuint effectslot, ALenum param, ALfloat *value)
{
    ContextRef context{GetContextRef()};
    if(UNLIKELY(!context)) return;

    std::lock_guard<std::mutex> _{context->EffectSlotLock};
    ALeffectslot *slot = LookupEffectSlot(context.get(), effectslot);
    if(UNLIKELY(!slot))
        SETERR_RETURN(context.get(), AL_INVALID_NAME,, "Invalid effect slot ID %u", effectslot);

    switch(param)
    {
    case AL_EFFECTSLOT_GAIN:
        *value = slot->Gain;
        break;

    default:
        SETERR_RETURN(context.get(), AL_INVALID_ENUM,,
                      "Invalid effect slot float property 0x%04x", param);
    }
}

AL_API ALvoid AL_APIENTRY alGetAuxiliaryEffectSlotfv(ALuint effectslot, ALenum param, ALfloat *values)
{
    switch(param)
    {
    case AL_EFFECTSLOT_GAIN:
        alGetAuxiliaryEffectSlotf(effectslot, param, values);
        return;
    }

    ContextRef context{GetContextRef()};
    if(UNLIKELY(!context)) return;

    std::lock_guard<std::mutex> _{context->EffectSlotLock};
    ALeffectslot *slot = LookupEffectSlot(context.get(), effectslot);
    if(UNLIKELY(!slot))
        SETERR_RETURN(context.get(), AL_INVALID_NAME,, "Invalid effect slot ID %u", effectslot);

    switch(param)
    {
    default:
        SETERR_RETURN(context.get(), AL_INVALID_ENUM,,
                      "Invalid effect slot float-vector property 0x%04x", param);
    }
}


ALenum InitializeEffect(ALCcontext *Context, ALeffectslot *EffectSlot, ALeffect *effect)
{
    ALenum newtype{effect ? effect->type : AL_EFFECT_NULL};
    if(newtype != EffectSlot->Effect.Type)
    {
        EffectStateFactory *factory{getFactoryByType(newtype)};
        if(!factory)
        {
            ERR("Failed to find factory for effect type 0x%04x\n", newtype);
            return AL_INVALID_ENUM;
        }
        EffectState *State{factory->create()};
        if(!State) return AL_OUT_OF_MEMORY;

        FPUCtl mixer_mode{};
        ALCdevice *Device{Context->Device};
        std::unique_lock<std::mutex> statelock{Device->StateLock};
        State->mOutBuffer = Device->Dry.Buffer;
        State->mOutChannels = Device->Dry.NumChannels;
        if(State->deviceUpdate(Device) == AL_FALSE)
        {
            statelock.unlock();
            mixer_mode.leave();
            State->DecRef();
            return AL_OUT_OF_MEMORY;
        }
        mixer_mode.leave();

        if(!effect)
        {
            EffectSlot->Effect.Type = AL_EFFECT_NULL;
            EffectSlot->Effect.Props = EffectProps {};
        }
        else
        {
            EffectSlot->Effect.Type = effect->type;
            EffectSlot->Effect.Props = effect->Props;
        }

        EffectSlot->Effect.State->DecRef();
        EffectSlot->Effect.State = State;
    }
    else if(effect)
        EffectSlot->Effect.Props = effect->Props;

    /* Remove state references from old effect slot property updates. */
    ALeffectslotProps *props{Context->FreeEffectslotProps.load()};
    while(props)
    {
        if(props->State)
            props->State->DecRef();
        props->State = nullptr;
        props = props->next.load(std::memory_order_relaxed);
    }

    return AL_NO_ERROR;
}


void EffectState::IncRef() noexcept
{
    auto ref = IncrementRef(&mRef);
    TRACEREF("%p increasing refcount to %u\n", this, ref);
}

void EffectState::DecRef() noexcept
{
    auto ref = DecrementRef(&mRef);
    TRACEREF("%p decreasing refcount to %u\n", this, ref);
    if(ref == 0) delete this;
}


ALenum InitEffectSlot(ALeffectslot *slot)
{
    EffectStateFactory *factory{getFactoryByType(slot->Effect.Type)};
    if(!factory) return AL_INVALID_VALUE;
    slot->Effect.State = factory->create();
    if(!slot->Effect.State) return AL_OUT_OF_MEMORY;

    slot->Effect.State->IncRef();
    slot->Params.mEffectState = slot->Effect.State;
    return AL_NO_ERROR;
}

ALeffectslot::~ALeffectslot()
{
    if(Target)
        DecrementRef(&Target->ref);
    Target = nullptr;

    ALeffectslotProps *props{Update.load()};
    if(props)
    {
        if(props->State) props->State->DecRef();
        TRACE("Freed unapplied AuxiliaryEffectSlot update %p\n", props);
        al_free(props);
    }

    if(Effect.State)
        Effect.State->DecRef();
    if(Params.mEffectState)
        Params.mEffectState->DecRef();
}

void UpdateEffectSlotProps(ALeffectslot *slot, ALCcontext *context)
{
    /* Get an unused property container, or allocate a new one as needed. */
    ALeffectslotProps *props{context->FreeEffectslotProps.load(std::memory_order_relaxed)};
    if(!props)
        props = static_cast<ALeffectslotProps*>(al_calloc(16, sizeof(*props)));
    else
    {
        ALeffectslotProps *next;
        do {
            next = props->next.load(std::memory_order_relaxed);
        } while(context->FreeEffectslotProps.compare_exchange_weak(props, next,
                std::memory_order_seq_cst, std::memory_order_acquire) == 0);
    }

    /* Copy in current property values. */
    props->Gain = slot->Gain;
    props->AuxSendAuto = slot->AuxSendAuto;
    props->Target = slot->Target;

    props->Type = slot->Effect.Type;
    props->Props = slot->Effect.Props;
    /* Swap out any stale effect state object there may be in the container, to
     * delete it.
     */
    EffectState *oldstate{props->State};
    slot->Effect.State->IncRef();
    props->State = slot->Effect.State;

    /* Set the new container for updating internal parameters. */
    props = slot->Update.exchange(props, std::memory_order_acq_rel);
    if(props)
    {
        /* If there was an unused update container, put it back in the
         * freelist.
         */
        if(props->State)
            props->State->DecRef();
        props->State = nullptr;
        AtomicReplaceHead(context->FreeEffectslotProps, props);
    }

    if(oldstate)
        oldstate->DecRef();
}

void UpdateAllEffectSlotProps(ALCcontext *context)
{
    std::lock_guard<std::mutex> _{context->EffectSlotLock};
    ALeffectslotArray *auxslots{context->ActiveAuxSlots.load(std::memory_order_acquire)};
    for(ALeffectslot *slot : *auxslots)
    {
        if(!slot->PropsClean.test_and_set(std::memory_order_acq_rel))
            UpdateEffectSlotProps(slot, context);
    }
}

EffectSlotSubList::~EffectSlotSubList()
{
    uint64_t usemask{~FreeMask};
    while(usemask)
    {
        ALsizei idx{CTZ64(usemask)};
        EffectSlots[idx].~ALeffectslot();
        usemask &= ~(1_u64 << idx);
    }
    FreeMask = ~usemask;
    al_free(EffectSlots);
    EffectSlots = nullptr;
}