/**
 * 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 <stdlib.h>

#include <algorithm>

#include "alMain.h"
#include "alcontext.h"
#include "alu.h"
#include "alFilter.h"
#include "alError.h"


namespace {

#define FILTER_MIN_GAIN 0.0f
#define FILTER_MAX_GAIN 4.0f /* +12dB */

void ALlowpass_setParami(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALint UNUSED(val))
{ alSetError(context, AL_INVALID_ENUM, "Invalid low-pass integer property 0x%04x", param); }
void ALlowpass_setParamiv(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, const ALint *UNUSED(vals))
{ alSetError(context, AL_INVALID_ENUM, "Invalid low-pass integer-vector property 0x%04x", param); }
void ALlowpass_setParamf(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat val)
{
    switch(param)
    {
        case AL_LOWPASS_GAIN:
            if(!(val >= FILTER_MIN_GAIN && val <= FILTER_MAX_GAIN))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Low-pass gain %f out of range", val);
            filter->Gain = val;
            break;

        case AL_LOWPASS_GAINHF:
            if(!(val >= AL_LOWPASS_MIN_GAINHF && val <= AL_LOWPASS_MAX_GAINHF))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Low-pass gainhf %f out of range", val);
            filter->GainHF = val;
            break;

        default:
            alSetError(context, AL_INVALID_ENUM, "Invalid low-pass float property 0x%04x", param);
    }
}
void ALlowpass_setParamfv(ALfilter *filter, ALCcontext *context, ALenum param, const ALfloat *vals)
{ ALlowpass_setParamf(filter, context, param, vals[0]); }

void ALlowpass_getParami(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALint *UNUSED(val))
{ alSetError(context, AL_INVALID_ENUM, "Invalid low-pass integer property 0x%04x", param); }
void ALlowpass_getParamiv(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALint *UNUSED(vals))
{ alSetError(context, AL_INVALID_ENUM, "Invalid low-pass integer-vector property 0x%04x", param); }
void ALlowpass_getParamf(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *val)
{
    switch(param)
    {
        case AL_LOWPASS_GAIN:
            *val = filter->Gain;
            break;

        case AL_LOWPASS_GAINHF:
            *val = filter->GainHF;
            break;

        default:
            alSetError(context, AL_INVALID_ENUM, "Invalid low-pass float property 0x%04x", param);
    }
}
void ALlowpass_getParamfv(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *vals)
{ ALlowpass_getParamf(filter, context, param, vals); }

DEFINE_ALFILTER_VTABLE(ALlowpass);


void ALhighpass_setParami(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALint UNUSED(val))
{ alSetError(context, AL_INVALID_ENUM, "Invalid high-pass integer property 0x%04x", param); }
void ALhighpass_setParamiv(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, const ALint *UNUSED(vals))
{ alSetError(context, AL_INVALID_ENUM, "Invalid high-pass integer-vector property 0x%04x", param); }
void ALhighpass_setParamf(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat val)
{
    switch(param)
    {
        case AL_HIGHPASS_GAIN:
            if(!(val >= FILTER_MIN_GAIN && val <= FILTER_MAX_GAIN))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "High-pass gain out of range");
            filter->Gain = val;
            break;

        case AL_HIGHPASS_GAINLF:
            if(!(val >= AL_HIGHPASS_MIN_GAINLF && val <= AL_HIGHPASS_MAX_GAINLF))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "High-pass gainlf out of range");
            filter->GainLF = val;
            break;

        default:
            alSetError(context, AL_INVALID_ENUM, "Invalid high-pass float property 0x%04x", param);
    }
}
void ALhighpass_setParamfv(ALfilter *filter, ALCcontext *context, ALenum param, const ALfloat *vals)
{ ALhighpass_setParamf(filter, context, param, vals[0]); }

void ALhighpass_getParami(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALint *UNUSED(val))
{ alSetError(context, AL_INVALID_ENUM, "Invalid high-pass integer property 0x%04x", param); }
void ALhighpass_getParamiv(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALint *UNUSED(vals))
{ alSetError(context, AL_INVALID_ENUM, "Invalid high-pass integer-vector property 0x%04x", param); }
void ALhighpass_getParamf(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *val)
{
    switch(param)
    {
        case AL_HIGHPASS_GAIN:
            *val = filter->Gain;
            break;

        case AL_HIGHPASS_GAINLF:
            *val = filter->GainLF;
            break;

        default:
            alSetError(context, AL_INVALID_ENUM, "Invalid high-pass float property 0x%04x", param);
    }
}
void ALhighpass_getParamfv(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *vals)
{ ALhighpass_getParamf(filter, context, param, vals); }

DEFINE_ALFILTER_VTABLE(ALhighpass);


void ALbandpass_setParami(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALint UNUSED(val))
{ alSetError(context, AL_INVALID_ENUM, "Invalid band-pass integer property 0x%04x", param); }
void ALbandpass_setParamiv(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, const ALint *UNUSED(vals))
{ alSetError(context, AL_INVALID_ENUM, "Invalid band-pass integer-vector property 0x%04x", param); }
void ALbandpass_setParamf(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat val)
{
    switch(param)
    {
        case AL_BANDPASS_GAIN:
            if(!(val >= FILTER_MIN_GAIN && val <= FILTER_MAX_GAIN))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Band-pass gain out of range");
            filter->Gain = val;
            break;

        case AL_BANDPASS_GAINHF:
            if(!(val >= AL_BANDPASS_MIN_GAINHF && val <= AL_BANDPASS_MAX_GAINHF))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Band-pass gainhf out of range");
            filter->GainHF = val;
            break;

        case AL_BANDPASS_GAINLF:
            if(!(val >= AL_BANDPASS_MIN_GAINLF && val <= AL_BANDPASS_MAX_GAINLF))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Band-pass gainlf out of range");
            filter->GainLF = val;
            break;

        default:
            alSetError(context, AL_INVALID_ENUM, "Invalid band-pass float property 0x%04x", param);
    }
}
void ALbandpass_setParamfv(ALfilter *filter, ALCcontext *context, ALenum param, const ALfloat *vals)
{ ALbandpass_setParamf(filter, context, param, vals[0]); }

void ALbandpass_getParami(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALint *UNUSED(val))
{ alSetError(context, AL_INVALID_ENUM, "Invalid band-pass integer property 0x%04x", param); }
void ALbandpass_getParamiv(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALint *UNUSED(vals))
{ alSetError(context, AL_INVALID_ENUM, "Invalid band-pass integer-vector property 0x%04x", param); }
void ALbandpass_getParamf(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *val)
{
    switch(param)
    {
        case AL_BANDPASS_GAIN:
            *val = filter->Gain;
            break;

        case AL_BANDPASS_GAINHF:
            *val = filter->GainHF;
            break;

        case AL_BANDPASS_GAINLF:
            *val = filter->GainLF;
            break;

        default:
            alSetError(context, AL_INVALID_ENUM, "Invalid band-pass float property 0x%04x", param);
    }
}
void ALbandpass_getParamfv(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *vals)
{ ALbandpass_getParamf(filter, context, param, vals); }

DEFINE_ALFILTER_VTABLE(ALbandpass);


void ALnullfilter_setParami(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALint UNUSED(val))
{ alSetError(context, AL_INVALID_ENUM, "Invalid null filter property 0x%04x", param); }
void ALnullfilter_setParamiv(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, const ALint *UNUSED(vals))
{ alSetError(context, AL_INVALID_ENUM, "Invalid null filter property 0x%04x", param); }
void ALnullfilter_setParamf(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALfloat UNUSED(val))
{ alSetError(context, AL_INVALID_ENUM, "Invalid null filter property 0x%04x", param); }
void ALnullfilter_setParamfv(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, const ALfloat *UNUSED(vals))
{ alSetError(context, AL_INVALID_ENUM, "Invalid null filter property 0x%04x", param); }

void ALnullfilter_getParami(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALint *UNUSED(val))
{ alSetError(context, AL_INVALID_ENUM, "Invalid null filter property 0x%04x", param); }
void ALnullfilter_getParamiv(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALint *UNUSED(vals))
{ alSetError(context, AL_INVALID_ENUM, "Invalid null filter property 0x%04x", param); }
void ALnullfilter_getParamf(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALfloat *UNUSED(val))
{ alSetError(context, AL_INVALID_ENUM, "Invalid null filter property 0x%04x", param); }
void ALnullfilter_getParamfv(ALfilter *UNUSED(filter), ALCcontext *context, ALenum param, ALfloat *UNUSED(vals))
{ alSetError(context, AL_INVALID_ENUM, "Invalid null filter property 0x%04x", param); }

DEFINE_ALFILTER_VTABLE(ALnullfilter);


void InitFilterParams(ALfilter *filter, ALenum type)
{
    if(type == AL_FILTER_LOWPASS)
    {
        filter->Gain = AL_LOWPASS_DEFAULT_GAIN;
        filter->GainHF = AL_LOWPASS_DEFAULT_GAINHF;
        filter->HFReference = LOWPASSFREQREF;
        filter->GainLF = 1.0f;
        filter->LFReference = HIGHPASSFREQREF;
        filter->vtab = &ALlowpass_vtable;
    }
    else if(type == AL_FILTER_HIGHPASS)
    {
        filter->Gain = AL_HIGHPASS_DEFAULT_GAIN;
        filter->GainHF = 1.0f;
        filter->HFReference = LOWPASSFREQREF;
        filter->GainLF = AL_HIGHPASS_DEFAULT_GAINLF;
        filter->LFReference = HIGHPASSFREQREF;
        filter->vtab = &ALhighpass_vtable;
    }
    else if(type == AL_FILTER_BANDPASS)
    {
        filter->Gain = AL_BANDPASS_DEFAULT_GAIN;
        filter->GainHF = AL_BANDPASS_DEFAULT_GAINHF;
        filter->HFReference = LOWPASSFREQREF;
        filter->GainLF = AL_BANDPASS_DEFAULT_GAINLF;
        filter->LFReference = HIGHPASSFREQREF;
        filter->vtab = &ALbandpass_vtable;
    }
    else
    {
        filter->Gain = 1.0f;
        filter->GainHF = 1.0f;
        filter->HFReference = LOWPASSFREQREF;
        filter->GainLF = 1.0f;
        filter->LFReference = HIGHPASSFREQREF;
        filter->vtab = &ALnullfilter_vtable;
    }
    filter->type = type;
}

ALfilter *AllocFilter(ALCcontext *context)
{
    ALCdevice *device = context->Device;
    almtx_lock(&device->FilterLock);

    auto sublist = std::find_if(device->FilterList.begin(), device->FilterList.end(),
        [](const FilterSubList &entry) noexcept -> bool
        { return entry.FreeMask != 0; }
    );

    auto lidx = std::distance(device->FilterList.begin(), sublist);
    ALfilter *filter{nullptr};
    ALsizei slidx{0};
    if(LIKELY(sublist != device->FilterList.end()))
    {
        slidx = CTZ64(sublist->FreeMask);
        filter = sublist->Filters + slidx;
    }
    else
    {
        /* Don't allocate so many list entries that the 32-bit ID could
         * overflow...
         */
        if(UNLIKELY(device->FilterList.size() >= 1<<25))
        {
            almtx_unlock(&device->FilterLock);
            alSetError(context, AL_OUT_OF_MEMORY, "Too many filters allocated");
            return NULL;
        }
        device->FilterList.emplace_back();
        sublist = device->FilterList.end() - 1;
        sublist->FreeMask = ~U64(0);
        sublist->Filters = static_cast<ALfilter*>(al_calloc(16, sizeof(ALfilter)*64));
        if(UNLIKELY(!sublist->Filters))
        {
            device->FilterList.pop_back();
            almtx_unlock(&device->FilterLock);
            alSetError(context, AL_OUT_OF_MEMORY, "Failed to allocate filter batch");
            return NULL;
        }

        slidx = 0;
        filter = sublist->Filters + slidx;
    }

    filter = new (filter) ALfilter{};
    InitFilterParams(filter, AL_FILTER_NULL);

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

    sublist->FreeMask &= ~(U64(1)<<slidx);
    almtx_unlock(&device->FilterLock);

    return filter;
}

void FreeFilter(ALCdevice *device, ALfilter *filter)
{
    ALuint id = filter->id - 1;
    ALsizei lidx = id >> 6;
    ALsizei slidx = id & 0x3f;

    filter->~ALfilter();

    device->FilterList[lidx].FreeMask |= U64(1) << slidx;
}


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

    if(UNLIKELY(lidx >= device->FilterList.size()))
        return nullptr;
    FilterSubList &sublist = device->FilterList[lidx];
    if(UNLIKELY(sublist.FreeMask & (U64(1)<<slidx)))
        return nullptr;
    return sublist.Filters + slidx;
}

} // namespace

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

    if(UNLIKELY(n < 0))
    {
        alSetError(context.get(), AL_INVALID_VALUE, "Generating %d filters", n);
        return;
    }

    if(LIKELY(n == 1))
    {
        /* Special handling for the easy and normal case. */
        ALfilter *filter = AllocFilter(context.get());
        if(filter) filters[0] = filter->id;
    }
    else if(n > 1)
    {
        /* Store the allocated buffer IDs in a separate local list, to avoid
         * modifying the user storage in case of failure.
         */
        al::vector<ALuint> ids;
        ids.reserve(n);
        do {
            ALfilter *filter = AllocFilter(context.get());
            if(!filter)
            {
                alDeleteFilters(ids.size(), ids.data());
                return;
            }

            ids.emplace_back(filter->id);
        } while(--n);
        std::copy(ids.begin(), ids.end(), filters);
    }
}

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

    if(UNLIKELY(n < 0))
    {
        alSetError(context.get(), AL_INVALID_VALUE, "Deleting %d filters", n);
        return;
    }
    if(UNLIKELY(n == 0))
        return;

    ALCdevice *device{context->Device};
    std::lock_guard<almtx_t> _{device->FilterLock};

    /* First try to find any filters that are invalid. */
    const ALuint *filters_end = filters + n;
    auto invflt = std::find_if(filters, filters_end,
        [device, &context](ALuint fid) -> bool
        {
            if(!fid) return false;
            ALfilter *filter{LookupFilter(device, fid)};
            if(UNLIKELY(!filter))
            {
                alSetError(context.get(), AL_INVALID_NAME, "Invalid filter ID %u", fid);
                return true;
            }
            return false;
        }
    );
    if(LIKELY(invflt == filters_end))
    {
        /* All good. Delete non-0 filter IDs. */
        std::for_each(filters, filters_end,
            [device](ALuint fid) -> void
            {
                ALfilter *filter{fid ? LookupFilter(device, fid) : nullptr};
                if(filter) FreeFilter(device, filter);
            }
        );
    }
}

AL_API ALboolean AL_APIENTRY alIsFilter(ALuint filter)
{
    ContextRef context{GetContextRef()};
    if(LIKELY(context))
    {
        ALCdevice *device{context->Device};
        std::lock_guard<almtx_t> _{device->FilterLock};
        if(!filter || LookupFilter(device, filter))
            return AL_TRUE;
    }
    return AL_FALSE;
}


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

    ALCdevice *device{context->Device};
    std::lock_guard<almtx_t> _{device->FilterLock};

    ALfilter *alfilt{LookupFilter(device, filter)};
    if(UNLIKELY(!alfilt))
        alSetError(context.get(), AL_INVALID_NAME, "Invalid filter ID %u", filter);
    else
    {
        if(param == AL_FILTER_TYPE)
        {
            if(value == AL_FILTER_NULL || value == AL_FILTER_LOWPASS ||
               value == AL_FILTER_HIGHPASS || value == AL_FILTER_BANDPASS)
                InitFilterParams(alfilt, value);
            else
                alSetError(context.get(), AL_INVALID_VALUE, "Invalid filter type 0x%04x", value);
        }
        else
        {
            /* Call the appropriate handler */
            ALfilter_setParami(alfilt, context.get(), param, value);
        }
    }
}

AL_API ALvoid AL_APIENTRY alFilteriv(ALuint filter, ALenum param, const ALint *values)
{
    switch(param)
    {
        case AL_FILTER_TYPE:
            alFilteri(filter, param, values[0]);
            return;
    }

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

    ALCdevice *device{context->Device};
    std::lock_guard<almtx_t> _{device->FilterLock};

    ALfilter *alfilt{LookupFilter(device, filter)};
    if(UNLIKELY(!alfilt))
        alSetError(context.get(), AL_INVALID_NAME, "Invalid filter ID %u", filter);
    else
    {
        /* Call the appropriate handler */
        ALfilter_setParamiv(alfilt, context.get(), param, values);
    }
}

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

    ALCdevice *device{context->Device};
    std::lock_guard<almtx_t> _{device->FilterLock};

    ALfilter *alfilt{LookupFilter(device, filter)};
    if(UNLIKELY(!alfilt))
        alSetError(context.get(), AL_INVALID_NAME, "Invalid filter ID %u", filter);
    else
    {
        /* Call the appropriate handler */
        ALfilter_setParamf(alfilt, context.get(), param, value);
    }
}

AL_API ALvoid AL_APIENTRY alFilterfv(ALuint filter, ALenum param, const ALfloat *values)
{
    ContextRef context{GetContextRef()};
    if(UNLIKELY(!context)) return;

    ALCdevice *device{context->Device};
    std::lock_guard<almtx_t> _{device->FilterLock};

    ALfilter *alfilt{LookupFilter(device, filter)};
    if(UNLIKELY(!alfilt))
        alSetError(context.get(), AL_INVALID_NAME, "Invalid filter ID %u", filter);
    else
    {
        /* Call the appropriate handler */
        ALfilter_setParamfv(alfilt, context.get(), param, values);
    }
}

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

    ALCdevice *device{context->Device};
    std::lock_guard<almtx_t> _{device->FilterLock};

    ALfilter *alfilt{LookupFilter(device, filter)};
    if(UNLIKELY(!alfilt))
        alSetError(context.get(), AL_INVALID_NAME, "Invalid filter ID %u", filter);
    else
    {
        if(param == AL_FILTER_TYPE)
            *value = alfilt->type;
        else
        {
            /* Call the appropriate handler */
            ALfilter_getParami(alfilt, context.get(), param, value);
        }
    }
}

AL_API ALvoid AL_APIENTRY alGetFilteriv(ALuint filter, ALenum param, ALint *values)
{
    switch(param)
    {
        case AL_FILTER_TYPE:
            alGetFilteri(filter, param, values);
            return;
    }

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

    ALCdevice *device{context->Device};
    std::lock_guard<almtx_t> _{device->FilterLock};

    ALfilter *alfilt{LookupFilter(device, filter)};
    if(UNLIKELY(!alfilt))
        alSetError(context.get(), AL_INVALID_NAME, "Invalid filter ID %u", filter);
    else
    {
        /* Call the appropriate handler */
        ALfilter_getParamiv(alfilt, context.get(), param, values);
    }
}

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

    ALCdevice *device{context->Device};
    std::lock_guard<almtx_t> _{device->FilterLock};

    ALfilter *alfilt{LookupFilter(device, filter)};
    if(UNLIKELY(!alfilt))
        alSetError(context.get(), AL_INVALID_NAME, "Invalid filter ID %u", filter);
    else
    {
        /* Call the appropriate handler */
        ALfilter_getParamf(alfilt, context.get(), param, value);
    }
}

AL_API ALvoid AL_APIENTRY alGetFilterfv(ALuint filter, ALenum param, ALfloat *values)
{
    ContextRef context{GetContextRef()};
    if(UNLIKELY(!context)) return;

    ALCdevice *device{context->Device};
    std::lock_guard<almtx_t> _{device->FilterLock};

    ALfilter *alfilt{LookupFilter(device, filter)};
    if(UNLIKELY(!alfilt))
        alSetError(context.get(), AL_INVALID_NAME, "Invalid filter ID %u", filter);
    else
    {
        /* Call the appropriate handler */
        ALfilter_getParamfv(alfilt, context.get(), param, values);
    }
}


void ReleaseALFilters(ALCdevice *device)
{
    size_t leftover = 0;
    for(auto &sublist : device->FilterList)
    {
        ALuint64 usemask = ~sublist.FreeMask;
        while(usemask)
        {
            ALsizei idx = CTZ64(usemask);
            ALfilter *filter = sublist.Filters + idx;

            filter->~ALfilter();
            ++leftover;

            usemask &= ~(U64(1) << idx);
        }
        sublist.FreeMask = ~usemask;
    }
    if(leftover > 0)
        WARN("(%p) Deleted " SZFMT " Filter%s\n", device, leftover, (leftover==1)?"":"s");
}