Avoid global constexpr arrays

10 files changed, 172 insertions, 154 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9eb7aa07..558b0b4e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -648,7 +648,6 @@ set(COMMON_OBJS
 set(CORE_OBJS
     core/ambdec.cpp
     core/ambdec.h
-    core/ambidefs.cpp
     core/ambidefs.h
     core/bs2b.cpp
     core/bs2b.h
diff --git a/al/source.cpp b/al/source.cpp
index cf536f2b..770e3778 100644
--- a/al/source.cpp
+++ b/al/source.cpp
@@ -471,8 +471,8 @@ void InitVoice(Voice *voice, ALsource *source, BufferlistItem *BufferList, ALCco
     if(voice->mAmbiOrder && device->mAmbiOrder > voice->mAmbiOrder)
     {
         const uint8_t *OrderFromChan{(voice->mFmtChannels == FmtBFormat2D) ?
-            AmbiIndex::OrderFrom2DChannel.data() :
-            AmbiIndex::OrderFromChannel.data()};
+            AmbiIndex::OrderFrom2DChannel().data() :
+            AmbiIndex::OrderFromChannel().data()};
         const auto scales = BFormatDec::GetHFOrderScales(voice->mAmbiOrder, device->mAmbiOrder);
 
         const BandSplitter splitter{device->mXOverFreq / static_cast<float>(device->Frequency)};
diff --git a/alc/alc.cpp b/alc/alc.cpp
index 8cd902ed..2b9eb2df 100644
--- a/alc/alc.cpp
+++ b/alc/alc.cpp
@@ -2212,8 +2212,8 @@ static ALCenum UpdateDeviceParams(ALCdevice *device, const int *attrList)
             if(voice->mAmbiOrder && device->mAmbiOrder > voice->mAmbiOrder)
             {
                 const uint8_t *OrderFromChan{(voice->mFmtChannels == FmtBFormat2D) ?
-                    AmbiIndex::OrderFrom2DChannel.data() :
-                    AmbiIndex::OrderFromChannel.data()};
+                    AmbiIndex::OrderFrom2DChannel().data() :
+                    AmbiIndex::OrderFromChannel().data()};
 
                 const BandSplitter splitter{device->mXOverFreq /
                     static_cast<float>(device->Frequency)};
diff --git a/alc/alu.cpp b/alc/alu.cpp
index fe4c54a1..0cbfefec 100644
--- a/alc/alu.cpp
+++ b/alc/alu.cpp
@@ -345,23 +345,23 @@ inline uint dither_rng(uint *seed) noexcept
 }
 
 
-auto GetAmbiScales(AmbiScaling scaletype) noexcept -> const std::array<float,MaxAmbiChannels>&
+inline auto& GetAmbiScales(AmbiScaling scaletype) noexcept
 {
-    if(scaletype == AmbiScaling::FuMa) return AmbiScale::FromFuMa;
-    if(scaletype == AmbiScaling::SN3D) return AmbiScale::FromSN3D;
-    return AmbiScale::FromN3D;
+    if(scaletype == AmbiScaling::FuMa) return AmbiScale::FromFuMa();
+    if(scaletype == AmbiScaling::SN3D) return AmbiScale::FromSN3D();
+    return AmbiScale::FromN3D();
 }
 
-auto GetAmbiLayout(AmbiLayout layouttype) noexcept -> const std::array<uint8_t,MaxAmbiChannels>&
+inline auto& GetAmbiLayout(AmbiLayout layouttype) noexcept
 {
-    if(layouttype == AmbiLayout::FuMa) return AmbiIndex::FromFuMa;
-    return AmbiIndex::FromACN;
+    if(layouttype == AmbiLayout::FuMa) return AmbiIndex::FromFuMa();
+    return AmbiIndex::FromACN();
 }
 
-auto GetAmbi2DLayout(AmbiLayout layouttype) noexcept -> const std::array<uint8_t,MaxAmbi2DChannels>&
+inline auto& GetAmbi2DLayout(AmbiLayout layouttype) noexcept
 {
-    if(layouttype == AmbiLayout::FuMa) return AmbiIndex::FromFuMa2D;
-    return AmbiIndex::FromACN2D;
+    if(layouttype == AmbiLayout::FuMa) return AmbiIndex::FromFuMa2D();
+    return AmbiIndex::FromACN2D();
 }
 
 
@@ -855,7 +855,7 @@ void CalcPanningAndFilters(Voice *voice, const float xpos, const float ypos, con
             std::bind(std::multiplies<float>{}, _1, 1.0f-coverage));
 
         /* NOTE: W needs to be scaled according to channel scaling. */
-        const auto &scales = GetAmbiScales(voice->mAmbiScaling);
+        auto&& scales = GetAmbiScales(voice->mAmbiScaling);
         ComputePanGains(&Device->Dry, coeffs.data(), DryGain.Base*scales[0],
             voice->mChans[0].mDryParams.Gains.Target);
         for(uint i{0};i < NumSends;i++)
@@ -907,7 +907,7 @@ void CalcPanningAndFilters(Voice *voice, const float xpos, const float ypos, con
             for(size_t c{1};c < num_channels;c++)
             {
                 const size_t acn{index_map[c]};
-                const size_t order{AmbiIndex::OrderFromChannel[acn]};
+                const size_t order{AmbiIndex::OrderFromChannel()[acn]};
                 const size_t tocopy{ChansPerOrder[order]};
                 const size_t offset{OrderOffset[order]};
                 const float scale{scales[acn] * coverage};
diff --git a/alc/bformatdec.cpp b/alc/bformatdec.cpp
index 64c45b68..9b2d9049 100644
--- a/alc/bformatdec.cpp
+++ b/alc/bformatdec.cpp
@@ -31,19 +31,18 @@ constexpr std::array<float,MaxAmbiOrder+1> Ambi3DDecoderHFScale3O{{
     5.89792205e-01f, 8.79693856e-01f, 1.00000000e+00f, 1.00000000e+00f
 }};
 
-inline auto GetDecoderHFScales(uint order) noexcept -> const std::array<float,MaxAmbiOrder+1>&
+inline auto& GetDecoderHFScales(uint order) noexcept
 {
     if(order >= 3) return Ambi3DDecoderHFScale3O;
     if(order == 2) return Ambi3DDecoderHFScale2O;
     return Ambi3DDecoderHFScale;
 }
 
-inline auto GetAmbiScales(AmbDecScale scaletype) noexcept
-    -> const std::array<float,MaxAmbiChannels>&
+inline auto& GetAmbiScales(AmbDecScale scaletype) noexcept
 {
-    if(scaletype == AmbDecScale::FuMa) return AmbiScale::FromFuMa;
-    if(scaletype == AmbDecScale::SN3D) return AmbiScale::FromSN3D;
-    return AmbiScale::FromN3D;
+    if(scaletype == AmbDecScale::FuMa) return AmbiScale::FromFuMa();
+    if(scaletype == AmbDecScale::SN3D) return AmbiScale::FromSN3D();
+    return AmbiScale::FromN3D();
 }
 
 } // namespace
@@ -56,15 +55,15 @@ BFormatDec::BFormatDec(const AmbDecConf *conf, const bool allow_2band, const siz
     , mChannelDec{inchans}
 {
     const bool periphonic{(conf->ChanMask&AmbiPeriphonicMask) != 0};
-    const std::array<float,MaxAmbiChannels> &coeff_scale = GetAmbiScales(conf->CoeffScale);
+    auto&& coeff_scale = GetAmbiScales(conf->CoeffScale);
 
     if(!mDualBand)
     {
         for(size_t j{0},k{0};j < mChannelDec.size();++j)
         {
-            const size_t acn{periphonic ? j : AmbiIndex::FromACN2D[j]};
+            const size_t acn{periphonic ? j : AmbiIndex::FromACN2D()[j]};
             if(!(conf->ChanMask&(1u<<acn))) continue;
-            const size_t order{AmbiIndex::OrderFromChannel[acn]};
+            const size_t order{AmbiIndex::OrderFromChannel()[acn]};
             const float gain{conf->HFOrderGain[order] / coeff_scale[acn]};
             for(size_t i{0u};i < conf->NumSpeakers;++i)
             {
@@ -83,9 +82,9 @@ BFormatDec::BFormatDec(const AmbDecConf *conf, const bool allow_2band, const siz
         const float ratio{std::pow(10.0f, conf->XOverRatio / 40.0f)};
         for(size_t j{0},k{0};j < mChannelDec.size();++j)
         {
-            const size_t acn{periphonic ? j : AmbiIndex::FromACN2D[j]};
+            const size_t acn{periphonic ? j : AmbiIndex::FromACN2D()[j]};
             if(!(conf->ChanMask&(1u<<acn))) continue;
-            const size_t order{AmbiIndex::OrderFromChannel[acn]};
+            const size_t order{AmbiIndex::OrderFromChannel()[acn]};
             const float hfGain{conf->HFOrderGain[order] * ratio / coeff_scale[acn]};
             const float lfGain{conf->LFOrderGain[order] / ratio / coeff_scale[acn]};
             for(size_t i{0u};i < conf->NumSpeakers;++i)
diff --git a/alc/effects/convolution.cpp b/alc/effects/convolution.cpp
index 4e10b62a..2dec0dc6 100644
--- a/alc/effects/convolution.cpp
+++ b/alc/effects/convolution.cpp
@@ -76,23 +76,23 @@ void LoadSamples(double *RESTRICT dst, const al::byte *src, const size_t srcstep
 }
 
 
-auto GetAmbiScales(AmbiScaling scaletype) noexcept -> const std::array<float,MaxAmbiChannels>&
+inline auto& GetAmbiScales(AmbiScaling scaletype) noexcept
 {
-    if(scaletype == AmbiScaling::FuMa) return AmbiScale::FromFuMa;
-    if(scaletype == AmbiScaling::SN3D) return AmbiScale::FromSN3D;
-    return AmbiScale::FromN3D;
+    if(scaletype == AmbiScaling::FuMa) return AmbiScale::FromFuMa();
+    if(scaletype == AmbiScaling::SN3D) return AmbiScale::FromSN3D();
+    return AmbiScale::FromN3D();
 }
 
-auto GetAmbiLayout(AmbiLayout layouttype) noexcept -> const std::array<uint8_t,MaxAmbiChannels>&
+inline auto& GetAmbiLayout(AmbiLayout layouttype) noexcept
 {
-    if(layouttype == AmbiLayout::FuMa) return AmbiIndex::FromFuMa;
-    return AmbiIndex::FromACN;
+    if(layouttype == AmbiLayout::FuMa) return AmbiIndex::FromFuMa();
+    return AmbiIndex::FromACN();
 }
 
-auto GetAmbi2DLayout(AmbiLayout layouttype) noexcept -> const std::array<uint8_t,MaxAmbi2DChannels>&
+inline auto& GetAmbi2DLayout(AmbiLayout layouttype) noexcept
 {
-    if(layouttype == AmbiLayout::FuMa) return AmbiIndex::FromFuMa2D;
-    return AmbiIndex::FromACN2D;
+    if(layouttype == AmbiLayout::FuMa) return AmbiIndex::FromFuMa2D();
+    return AmbiIndex::FromACN2D();
 }
 
 
@@ -387,7 +387,7 @@ void ConvolutionState::update(const ALCcontext *context, const EffectSlot *slot,
         }
         mOutTarget = target.Main->Buffer;
 
-        const auto &scales = GetAmbiScales(mAmbiScaling);
+        auto&& scales = GetAmbiScales(mAmbiScaling);
         const uint8_t *index_map{(mChannels == FmtBFormat2D) ?
             GetAmbi2DLayout(mAmbiLayout).data() :
             GetAmbiLayout(mAmbiLayout).data()};
diff --git a/alc/hrtf.cpp b/alc/hrtf.cpp
index 891f9cb4..4e32a0ba 100644
--- a/alc/hrtf.cpp
+++ b/alc/hrtf.cpp
@@ -291,7 +291,7 @@ void DirectHrtfState::build(const HrtfStore *Hrtf, const uint irSize,
     const double xover_norm{double{XOverFreq} / Hrtf->sampleRate};
     for(size_t i{0};i < mChannels.size();++i)
     {
-        const size_t order{AmbiIndex::OrderFromChannel[i]};
+        const size_t order{AmbiIndex::OrderFromChannel()[i]};
         mChannels[i].mSplitter.init(static_cast<float>(xover_norm));
         mChannels[i].mHfScale = AmbiOrderHFGain[order];
     }
diff --git a/alc/panning.cpp b/alc/panning.cpp
index c8a314b2..1ac3bb04 100644
--- a/alc/panning.cpp
+++ b/alc/panning.cpp
@@ -300,17 +300,17 @@ void InitDistanceComp(ALCdevice *device, const AmbDecConf *conf,
 }
 
 
-auto GetAmbiScales(DevAmbiScaling scaletype) noexcept -> const std::array<float,MaxAmbiChannels>&
+inline auto& GetAmbiScales(DevAmbiScaling scaletype) noexcept
 {
-    if(scaletype == DevAmbiScaling::FuMa) return AmbiScale::FromFuMa;
-    if(scaletype == DevAmbiScaling::SN3D) return AmbiScale::FromSN3D;
-    return AmbiScale::FromN3D;
+    if(scaletype == DevAmbiScaling::FuMa) return AmbiScale::FromFuMa();
+    if(scaletype == DevAmbiScaling::SN3D) return AmbiScale::FromSN3D();
+    return AmbiScale::FromN3D();
 }
 
-auto GetAmbiLayout(DevAmbiLayout layouttype) noexcept -> const std::array<uint8_t,MaxAmbiChannels>&
+inline auto& GetAmbiLayout(DevAmbiLayout layouttype) noexcept
 {
-    if(layouttype == DevAmbiLayout::FuMa) return AmbiIndex::FromFuMa;
-    return AmbiIndex::FromACN;
+    if(layouttype == DevAmbiLayout::FuMa) return AmbiIndex::FromFuMa();
+    return AmbiIndex::FromACN();
 }
 
 
@@ -492,8 +492,8 @@ void InitPanning(ALCdevice *device, const bool hqdec=false, const bool stablize=
     if(device->FmtChans == DevFmtAmbi3D)
     {
         const char *devname{device->DeviceName.c_str()};
-        const std::array<uint8_t,MaxAmbiChannels> &acnmap = GetAmbiLayout(device->mAmbiLayout);
-        const std::array<float,MaxAmbiChannels> &n3dscale = GetAmbiScales(device->mAmbiScale);
+        auto&& acnmap = GetAmbiLayout(device->mAmbiLayout);
+        auto&& n3dscale = GetAmbiScales(device->mAmbiScale);
 
         /* For DevFmtAmbi3D, the ambisonic order is already set. */
         const size_t count{AmbiChannelsFromOrder(device->mAmbiOrder)};
@@ -554,7 +554,7 @@ void InitPanning(ALCdevice *device, const bool hqdec=false, const bool stablize=
 
         /* Built-in speaker decoders are always 2D. */
         const size_t ambicount{Ambi2DChannelsFromOrder(decoder.mOrder)};
-        std::transform(AmbiIndex::FromACN2D.begin(), AmbiIndex::FromACN2D.begin()+ambicount,
+        std::transform(AmbiIndex::FromACN2D().begin(), AmbiIndex::FromACN2D().begin()+ambicount,
             std::begin(device->Dry.AmbiMap),
             [](const uint8_t &index) noexcept { return BFChannelConfig{1.0f, index}; }
         );
@@ -611,7 +611,7 @@ void InitCustomPanning(ALCdevice *device, const bool hqdec, const bool stablize,
     if((conf->ChanMask&AmbiPeriphonicMask))
     {
         count = AmbiChannelsFromOrder(order);
-        std::transform(AmbiIndex::FromACN.begin(), AmbiIndex::FromACN.begin()+count,
+        std::transform(AmbiIndex::FromACN().begin(), AmbiIndex::FromACN().begin()+count,
             std::begin(device->Dry.AmbiMap),
             [](const uint8_t &index) noexcept { return BFChannelConfig{1.0f, index}; }
         );
@@ -619,7 +619,7 @@ void InitCustomPanning(ALCdevice *device, const bool hqdec, const bool stablize,
     else
     {
         count = Ambi2DChannelsFromOrder(order);
-        std::transform(AmbiIndex::FromACN2D.begin(), AmbiIndex::FromACN2D.begin()+count,
+        std::transform(AmbiIndex::FromACN2D().begin(), AmbiIndex::FromACN2D().begin()+count,
             std::begin(device->Dry.AmbiMap),
             [](const uint8_t &index) noexcept { return BFChannelConfig{1.0f, index}; }
         );
@@ -812,7 +812,7 @@ void InitHrtfPanning(ALCdevice *device)
     device->mAmbiOrder = ambi_order;
 
     const size_t count{AmbiChannelsFromOrder(ambi_order)};
-    std::transform(AmbiIndex::FromACN.begin(), AmbiIndex::FromACN.begin()+count,
+    std::transform(AmbiIndex::FromACN().begin(), AmbiIndex::FromACN().begin()+count,
         std::begin(device->Dry.AmbiMap),
         [](const uint8_t &index) noexcept { return BFChannelConfig{1.0f, index}; }
     );
@@ -834,11 +834,10 @@ void InitUhjPanning(ALCdevice *device)
 
     device->mAmbiOrder = 1;
 
-    auto acnmap_end = AmbiIndex::FromFuMa.begin() + count;
-    std::transform(AmbiIndex::FromFuMa.begin(), acnmap_end, std::begin(device->Dry.AmbiMap),
+    auto acnmap_begin = AmbiIndex::FromFuMa().begin();
+    std::transform(acnmap_begin, acnmap_begin + count, std::begin(device->Dry.AmbiMap),
         [](const uint8_t &acn) noexcept -> BFChannelConfig
-        { return BFChannelConfig{1.0f/AmbiScale::FromFuMa[acn], acn}; }
-    );
+        { return BFChannelConfig{1.0f/AmbiScale::FromFuMa()[acn], acn}; });
     AllocChannels(device, count, device->channelsFromFmt());
 }
 
@@ -1092,8 +1091,8 @@ void aluInitEffectPanning(EffectSlot *slot, ALCcontext *context)
     WetBuffer *wetbuffer{slot->mWetBuffer = wetbuffer_iter->get()};
     wetbuffer->mInUse = true;
 
-    auto acnmap_end = AmbiIndex::FromACN.begin() + count;
-    auto iter = std::transform(AmbiIndex::FromACN.begin(), acnmap_end, slot->Wet.AmbiMap.begin(),
+    auto acnmap_begin = AmbiIndex::FromACN().begin();
+    auto iter = std::transform(acnmap_begin, acnmap_begin + count, slot->Wet.AmbiMap.begin(),
         [](const uint8_t &acn) noexcept -> BFChannelConfig
         { return BFChannelConfig{1.0f, acn}; });
     std::fill(iter, slot->Wet.AmbiMap.end(), BFChannelConfig{});
diff --git a/core/ambidefs.cpp b/core/ambidefs.cpp
deleted file mode 100644
index e032830f..00000000
--- a/core/ambidefs.cpp
+++ /dev/null
@@ -1,15 +0,0 @@
-
-#include "config.h"
-
-#include "ambidefs.h"
-
-
-constexpr std::array<float,MaxAmbiChannels> AmbiScale::FromN3D;
-constexpr std::array<float,MaxAmbiChannels> AmbiScale::FromSN3D;
-constexpr std::array<float,MaxAmbiChannels> AmbiScale::FromFuMa;
-constexpr std::array<uint8_t,MaxAmbiChannels> AmbiIndex::FromFuMa;
-constexpr std::array<uint8_t,MaxAmbi2DChannels> AmbiIndex::FromFuMa2D;
-constexpr std::array<uint8_t,MaxAmbiChannels> AmbiIndex::FromACN;
-constexpr std::array<uint8_t,MaxAmbi2DChannels> AmbiIndex::FromACN2D;
-constexpr std::array<uint8_t,MaxAmbiChannels> AmbiIndex::OrderFromChannel;
-constexpr std::array<uint8_t,MaxAmbi2DChannels> AmbiIndex::OrderFrom2DChannel;
diff --git a/core/ambidefs.h b/core/ambidefs.h
index ed8c27fb..a72f7b78 100644
--- a/core/ambidefs.h
+++ b/core/ambidefs.h
@@ -45,91 +45,127 @@ constexpr size_t MaxAmbi2DChannels{Ambi2DChannelsFromOrder(MaxAmbiOrder)};
  * coefficients should be divided by these values to get proper scalings.
  */
 struct AmbiScale {
-    static constexpr std::array<float,MaxAmbiChannels> FromN3D{{
-        1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
-        1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f
-    }};
-    static constexpr std::array<float,MaxAmbiChannels> FromSN3D{{
-        1.000000000f, /* ACN  0, sqrt(1) */
-        1.732050808f, /* ACN  1, sqrt(3) */
-        1.732050808f, /* ACN  2, sqrt(3) */
-        1.732050808f, /* ACN  3, sqrt(3) */
-        2.236067978f, /* ACN  4, sqrt(5) */
-        2.236067978f, /* ACN  5, sqrt(5) */
-        2.236067978f, /* ACN  6, sqrt(5) */
-        2.236067978f, /* ACN  7, sqrt(5) */
-        2.236067978f, /* ACN  8, sqrt(5) */
-        2.645751311f, /* ACN  9, sqrt(7) */
-        2.645751311f, /* ACN 10, sqrt(7) */
-        2.645751311f, /* ACN 11, sqrt(7) */
-        2.645751311f, /* ACN 12, sqrt(7) */
-        2.645751311f, /* ACN 13, sqrt(7) */
-        2.645751311f, /* ACN 14, sqrt(7) */
-        2.645751311f, /* ACN 15, sqrt(7) */
-    }};
-    static constexpr std::array<float,MaxAmbiChannels> FromFuMa{{
-        1.414213562f, /* ACN  0 (W), sqrt(2) */
-        1.732050808f, /* ACN  1 (Y), sqrt(3) */
-        1.732050808f, /* ACN  2 (Z), sqrt(3) */
-        1.732050808f, /* ACN  3 (X), sqrt(3) */
-        1.936491673f, /* ACN  4 (V), sqrt(15)/2 */
-        1.936491673f, /* ACN  5 (T), sqrt(15)/2 */
-        2.236067978f, /* ACN  6 (R), sqrt(5) */
-        1.936491673f, /* ACN  7 (S), sqrt(15)/2 */
-        1.936491673f, /* ACN  8 (U), sqrt(15)/2 */
-        2.091650066f, /* ACN  9 (Q), sqrt(35/8) */
-        1.972026594f, /* ACN 10 (O), sqrt(35)/3 */
-        2.231093404f, /* ACN 11 (M), sqrt(224/45) */
-        2.645751311f, /* ACN 12 (K), sqrt(7) */
-        2.231093404f, /* ACN 13 (L), sqrt(224/45) */
-        1.972026594f, /* ACN 14 (N), sqrt(35)/3 */
-        2.091650066f, /* ACN 15 (P), sqrt(35/8) */
-    }};
+    static auto& FromN3D() noexcept
+    {
+        static constexpr const std::array<float,MaxAmbiChannels> ret{{
+            1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
+            1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f
+        }};
+        return ret;
+    }
+    static auto& FromSN3D() noexcept
+    {
+        static constexpr const std::array<float,MaxAmbiChannels> ret{{
+            1.000000000f, /* ACN  0, sqrt(1) */
+            1.732050808f, /* ACN  1, sqrt(3) */
+            1.732050808f, /* ACN  2, sqrt(3) */
+            1.732050808f, /* ACN  3, sqrt(3) */
+            2.236067978f, /* ACN  4, sqrt(5) */
+            2.236067978f, /* ACN  5, sqrt(5) */
+            2.236067978f, /* ACN  6, sqrt(5) */
+            2.236067978f, /* ACN  7, sqrt(5) */
+            2.236067978f, /* ACN  8, sqrt(5) */
+            2.645751311f, /* ACN  9, sqrt(7) */
+            2.645751311f, /* ACN 10, sqrt(7) */
+            2.645751311f, /* ACN 11, sqrt(7) */
+            2.645751311f, /* ACN 12, sqrt(7) */
+            2.645751311f, /* ACN 13, sqrt(7) */
+            2.645751311f, /* ACN 14, sqrt(7) */
+            2.645751311f, /* ACN 15, sqrt(7) */
+        }};
+        return ret;
+    }
+    static auto& FromFuMa() noexcept
+    {
+        static constexpr const std::array<float,MaxAmbiChannels> ret{{
+            1.414213562f, /* ACN  0 (W), sqrt(2) */
+            1.732050808f, /* ACN  1 (Y), sqrt(3) */
+            1.732050808f, /* ACN  2 (Z), sqrt(3) */
+            1.732050808f, /* ACN  3 (X), sqrt(3) */
+            1.936491673f, /* ACN  4 (V), sqrt(15)/2 */
+            1.936491673f, /* ACN  5 (T), sqrt(15)/2 */
+            2.236067978f, /* ACN  6 (R), sqrt(5) */
+            1.936491673f, /* ACN  7 (S), sqrt(15)/2 */
+            1.936491673f, /* ACN  8 (U), sqrt(15)/2 */
+            2.091650066f, /* ACN  9 (Q), sqrt(35/8) */
+            1.972026594f, /* ACN 10 (O), sqrt(35)/3 */
+            2.231093404f, /* ACN 11 (M), sqrt(224/45) */
+            2.645751311f, /* ACN 12 (K), sqrt(7) */
+            2.231093404f, /* ACN 13 (L), sqrt(224/45) */
+            1.972026594f, /* ACN 14 (N), sqrt(35)/3 */
+            2.091650066f, /* ACN 15 (P), sqrt(35/8) */
+        }};
+        return ret;
+    }
 };
 
 struct AmbiIndex {
-    static constexpr std::array<uint8_t,MaxAmbiChannels> FromFuMa{{
-        0,  /* W */
-        3,  /* X */
-        1,  /* Y */
-        2,  /* Z */
-        6,  /* R */
-        7,  /* S */
-        5,  /* T */
-        8,  /* U */
-        4,  /* V */
-        12, /* K */
-        13, /* L */
-        11, /* M */
-        14, /* N */
-        10, /* O */
-        15, /* P */
-        9,  /* Q */
-    }};
-    static constexpr std::array<uint8_t,MaxAmbi2DChannels> FromFuMa2D{{
-        0,  /* W */
-        3,  /* X */
-        1,  /* Y */
-        8,  /* U */
-        4,  /* V */
-        15, /* P */
-        9,  /* Q */
-    }};
+    static auto& FromFuMa() noexcept
+    {
+        static constexpr const std::array<uint8_t,MaxAmbiChannels> ret{{
+            0,  /* W */
+            3,  /* X */
+            1,  /* Y */
+            2,  /* Z */
+            6,  /* R */
+            7,  /* S */
+            5,  /* T */
+            8,  /* U */
+            4,  /* V */
+            12, /* K */
+            13, /* L */
+            11, /* M */
+            14, /* N */
+            10, /* O */
+            15, /* P */
+            9,  /* Q */
+        }};
+        return ret;
+    }
+    static auto& FromFuMa2D() noexcept
+    {
+        static constexpr const std::array<uint8_t,MaxAmbi2DChannels> ret{{
+            0,  /* W */
+            3,  /* X */
+            1,  /* Y */
+            8,  /* U */
+            4,  /* V */
+            15, /* P */
+            9,  /* Q */
+        }};
+        return ret;
+    }
 
-    static constexpr std::array<uint8_t,MaxAmbiChannels> FromACN{{
-        0,  1,  2,  3,  4,  5,  6,  7,
-        8,  9, 10, 11, 12, 13, 14, 15
-    }};
-    static constexpr std::array<uint8_t,MaxAmbi2DChannels> FromACN2D{{
-        0, 1,3, 4,8, 9,15
-    }};
+    static auto& FromACN() noexcept
+    {
+        static constexpr const std::array<uint8_t,MaxAmbiChannels> ret{{
+            0,  1,  2,  3,  4,  5,  6,  7,
+            8,  9, 10, 11, 12, 13, 14, 15
+        }};
+        return ret;
+    }
+    static auto& FromACN2D() noexcept
+    {
+        static constexpr const std::array<uint8_t,MaxAmbi2DChannels> ret{{
+            0, 1,3, 4,8, 9,15
+        }};
+        return ret;
+    }
 
-    static constexpr std::array<uint8_t,MaxAmbiChannels> OrderFromChannel{{
-        0, 1,1,1, 2,2,2,2,2, 3,3,3,3,3,3,3,
-    }};
-    static constexpr std::array<uint8_t,MaxAmbi2DChannels> OrderFrom2DChannel{{
-        0, 1,1, 2,2, 3,3,
-    }};
+    static auto& OrderFromChannel() noexcept
+    {
+        static constexpr const std::array<uint8_t,MaxAmbiChannels> ret{{
+            0, 1,1,1, 2,2,2,2,2, 3,3,3,3,3,3,3,
+        }};
+        return ret;
+    }
+    static auto& OrderFrom2DChannel() noexcept
+    {
+        static constexpr const std::array<uint8_t,MaxAmbi2DChannels> ret{{
+            0, 1,1, 2,2, 3,3,
+        }};
+        return ret;
+    }
 };
 
 #endif /* CORE_AMBIDEFS_H */