text: /**
   * OpenAL cross platform audio library
   * Copyright (C) 2013 by Mike Gorchak
   * 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 <algorithm>
  #include <climits>
  #include <cmath>
  #include <cstdlib>
  #include <iterator>
  
  #include "AL/al.h"
  #include "AL/alc.h"
  #include "AL/efx.h"
  
  #include "al/auxeffectslot.h"
  #include "alcmain.h"
  #include "alcontext.h"
  #include "almalloc.h"
  #include "alnumeric.h"
  #include "alspan.h"
  #include "alu.h"
  #include "ambidefs.h"
  #include "effects/base.h"
  #include "math_defs.h"
  #include "opthelpers.h"
  #include "vector.h"
  
  
  namespace {
  
  static_assert(AL_CHORUS_WAVEFORM_SINUSOID == AL_FLANGER_WAVEFORM_SINUSOID, "Chorus/Flanger waveform value mismatch");
  static_assert(AL_CHORUS_WAVEFORM_TRIANGLE == AL_FLANGER_WAVEFORM_TRIANGLE, "Chorus/Flanger waveform value mismatch");
  
  enum class WaveForm {
      Sinusoid,
      Triangle
  };
  
  void GetTriangleDelays(ALuint *delays, const ALuint start_offset, const ALuint lfo_range,
      const ALfloat lfo_scale, const ALfloat depth, const ALsizei delay, const size_t todo)
  {
      ASSUME(lfo_range > 0);
      ASSUME(todo > 0);
  
      ALuint offset{start_offset};
      auto gen_lfo = [&offset,lfo_range,lfo_scale,depth,delay]() -> ALuint
      {
          offset = (offset+1)%lfo_range;
          const float offset_norm{static_cast<float>(offset) * lfo_scale};
          return static_cast<ALuint>(fastf2i((1.0f-std::abs(2.0f-offset_norm)) * depth) + delay);
      };
      std::generate_n(delays, todo, gen_lfo);
  }
  
  void GetSinusoidDelays(ALuint *delays, const ALuint start_offset, const ALuint lfo_range,
      const ALfloat lfo_scale, const ALfloat depth, const ALsizei delay, const size_t todo)
  {
      ASSUME(lfo_range > 0);
      ASSUME(todo > 0);
  
      ALuint offset{start_offset};
      auto gen_lfo = [&offset,lfo_range,lfo_scale,depth,delay]() -> ALuint
      {
          offset = (offset+1)%lfo_range;
          const float offset_norm{static_cast<float>(offset) * lfo_scale};
          return static_cast<ALuint>(fastf2i(std::sin(offset_norm)*depth) + delay);
      };
      std::generate_n(delays, todo, gen_lfo);
  }
  
  struct ChorusState final : public EffectState {
      al::vector<ALfloat,16> mSampleBuffer;
      ALuint mOffset{0};
  
      ALuint mLfoOffset{0};
      ALuint mLfoRange{1};
      ALfloat mLfoScale{0.0f};
      ALuint mLfoDisp{0};
  
      /* Gains for left and right sides */
      struct {
          ALfloat Current[MAX_OUTPUT_CHANNELS]{};
          ALfloat Target[MAX_OUTPUT_CHANNELS]{};
      } mGains[2];
  
      /* effect parameters */
      WaveForm mWaveform{};
      ALint mDelay{0};
      ALfloat mDepth{0.0f};
      ALfloat mFeedback{0.0f};
  
  
      ALboolean deviceUpdate(const ALCdevice *device) override;
      void update(const ALCcontext *context, const ALeffectslot *slot, const EffectProps *props, const EffectTarget target) override;
      void process(const size_t samplesToDo, const al::span<const FloatBufferLine> samplesIn, const al::span<FloatBufferLine> samplesOut) override;
  
      DEF_NEWDEL(ChorusState)
  };
  
  ALboolean ChorusState::deviceUpdate(const ALCdevice *Device)
  {
      constexpr ALfloat max_delay{maxf(AL_CHORUS_MAX_DELAY, AL_FLANGER_MAX_DELAY)};
  
      const auto frequency = static_cast<float>(Device->Frequency);
      const size_t maxlen{NextPowerOf2(float2uint(max_delay*2.0f*frequency) + 1u)};
      if(maxlen != mSampleBuffer.size())
      {
          mSampleBuffer.resize(maxlen);
          mSampleBuffer.shrink_to_fit();
      }
  
      std::fill(mSampleBuffer.begin(), mSampleBuffer.end(), 0.0f);
      for(auto &e : mGains)
      {
          std::fill(std::begin(e.Current), std::end(e.Current), 0.0f);
          std::fill(std::begin(e.Target), std::end(e.Target), 0.0f);
      }
  
      return AL_TRUE;
  }
  
  void ChorusState::update(const ALCcontext *Context, const ALeffectslot *Slot, const EffectProps *props, const EffectTarget target)
  {
      constexpr ALsizei mindelay{(MAX_RESAMPLER_PADDING>>1) << FRACTIONBITS};
  
      switch(props->Chorus.Waveform)
      {
          case AL_CHORUS_WAVEFORM_TRIANGLE:
              mWaveform = WaveForm::Triangle;
              break;
          case AL_CHORUS_WAVEFORM_SINUSOID:
              mWaveform = WaveForm::Sinusoid;
              break;
      }
  
      /* The LFO depth is scaled to be relative to the sample delay. Clamp the
       * delay and depth to allow enough padding for resampling.
       */
      const ALCdevice *device{Context->mDevice.get()};
      const auto frequency = static_cast<float>(device->Frequency);
  
      mDelay = maxi(float2int(props->Chorus.Delay*frequency*FRACTIONONE + 0.5f), mindelay);
      mDepth = minf(props->Chorus.Depth * static_cast<float>(mDelay),
          static_cast<float>(mDelay - mindelay));
  
      mFeedback = props->Chorus.Feedback;
  
      /* Gains for left and right sides */
      ALfloat coeffs[2][MAX_AMBI_CHANNELS];
      CalcDirectionCoeffs({-1.0f, 0.0f, 0.0f}, 0.0f, coeffs[0]);
      CalcDirectionCoeffs({ 1.0f, 0.0f, 0.0f}, 0.0f, coeffs[1]);
  
      mOutTarget = target.Main->Buffer;
      ComputePanGains(target.Main, coeffs[0], Slot->Params.Gain, mGains[0].Target);
      ComputePanGains(target.Main, coeffs[1], Slot->Params.Gain, mGains[1].Target);
  
      ALfloat rate{props->Chorus.Rate};
      if(!(rate > 0.0f))
      {
          mLfoOffset = 0;
          mLfoRange = 1;
          mLfoScale = 0.0f;
          mLfoDisp = 0;
      }
      else
      {
          /* Calculate LFO coefficient (number of samples per cycle). Limit the
           * max range to avoid overflow when calculating the displacement.
           */
          ALuint lfo_range{float2uint(minf(frequency/rate + 0.5f, ALfloat{INT_MAX/360 - 180}))};
  
          mLfoOffset = mLfoOffset * lfo_range / mLfoRange;
          mLfoRange = lfo_range;
          switch(mWaveform)
          {
              case WaveForm::Triangle:
                  mLfoScale = 4.0f / static_cast<float>(mLfoRange);
                  break;
              case WaveForm::Sinusoid:
                  mLfoScale = al::MathDefs<float>::Tau() / static_cast<float>(mLfoRange);
                  break;
          }
  
          /* Calculate lfo phase displacement */
          ALint phase{props->Chorus.Phase};
          if(phase < 0) phase = 360 + phase;
          mLfoDisp = (mLfoRange*static_cast<ALuint>(phase) + 180) / 360;
      }
  }
  
  void ChorusState::process(const size_t samplesToDo, const al::span<const FloatBufferLine> samplesIn, const al::span<FloatBufferLine> samplesOut)
  {
      const size_t bufmask{mSampleBuffer.size()-1};
      const ALfloat feedback{mFeedback};
      const ALuint avgdelay{(static_cast<ALuint>(mDelay) + (FRACTIONONE>>1)) >> FRACTIONBITS};
      ALfloat *RESTRICT delaybuf{mSampleBuffer.data()};
      ALuint offset{mOffset};
  
      for(size_t base{0u};base < samplesToDo;)
      {
          const size_t todo{minz(256, samplesToDo-base)};
  
          ALuint moddelays[2][256];
          if(mWaveform == WaveForm::Sinusoid)
          {
              GetSinusoidDelays(moddelays[0], mLfoOffset, mLfoRange, mLfoScale, mDepth, mDelay,
                                todo);
              GetSinusoidDelays(moddelays[1], (mLfoOffset+mLfoDisp)%mLfoRange, mLfoRange, mLfoScale,
                                mDepth, mDelay, todo);
          }
          else /*if(mWaveform == WaveForm::Triangle)*/
          {
              GetTriangleDelays(moddelays[0], mLfoOffset, mLfoRange, mLfoScale, mDepth, mDelay,
                                todo);
              GetTriangleDelays(moddelays[1], (mLfoOffset+mLfoDisp)%mLfoRange, mLfoRange, mLfoScale,
                                mDepth, mDelay, todo);
          }
          mLfoOffset = (mLfoOffset+static_cast<ALuint>(todo)) % mLfoRange;
  
          alignas(16) ALfloat temps[2][256];
          for(size_t i{0u};i < todo;i++)
          {
              // Feed the buffer's input first (necessary for delays < 1).
              delaybuf[offset&bufmask] = samplesIn[0][base+i];
  
              // Tap for the left output.
              ALuint delay{offset - (moddelays[0][i]>>FRACTIONBITS)};
              ALfloat mu{static_cast<float>(moddelays[0][i]&FRACTIONMASK) * (1.0f/FRACTIONONE)};
              temps[0][i] = cubic(delaybuf[(delay+1) & bufmask], delaybuf[(delay  ) & bufmask],
                  delaybuf[(delay-1) & bufmask], delaybuf[(delay-2) & bufmask], mu);
  
              // Tap for the right output.
              delay = offset - (moddelays[1][i]>>FRACTIONBITS);
              mu = static_cast<float>(moddelays[1][i]&FRACTIONMASK) * (1.0f/FRACTIONONE);
              temps[1][i] = cubic(delaybuf[(delay+1) & bufmask], delaybuf[(delay  ) & bufmask],
                  delaybuf[(delay-1) & bufmask], delaybuf[(delay-2) & bufmask], mu);
  
              // Accumulate feedback from the average delay of the taps.
              delaybuf[offset&bufmask] += delaybuf[(offset-avgdelay) & bufmask] * feedback;
              ++offset;
          }
  
          for(ALsizei c{0};c < 2;c++)
              MixSamples({temps[c], todo}, samplesOut, mGains[c].Current, mGains[c].Target,
                  samplesToDo-base, base);
  
          base += todo;
      }
  
      mOffset = offset;
  }
  
  
  void Chorus_setParami(EffectProps *props, ALCcontext *context, ALenum param, ALint val)
  {
      switch(param)
      {
          case AL_CHORUS_WAVEFORM:
              if(!(val >= AL_CHORUS_MIN_WAVEFORM && val <= AL_CHORUS_MAX_WAVEFORM))
                  SETERR_RETURN(context, AL_INVALID_VALUE,, "Invalid chorus waveform");
              props->Chorus.Waveform = val;
              break;
  
          case AL_CHORUS_PHASE:
              if(!(val >= AL_CHORUS_MIN_PHASE && val <= AL_CHORUS_MAX_PHASE))
                  SETERR_RETURN(context, AL_INVALID_VALUE,, "Chorus phase out of range");
              props->Chorus.Phase = val;
              break;
  
          default:
              context->setError(AL_INVALID_ENUM, "Invalid chorus integer property 0x%04x", param);
      }
  }
  void Chorus_setParamiv(EffectProps *props, ALCcontext *context, ALenum param, const ALint *vals)
  { Chorus_setParami(props, context, param, vals[0]); }
  void Chorus_setParamf(EffectProps *props, ALCcontext *context, ALenum param, ALfloat val)
  {
      switch(param)
      {
          case AL_CHORUS_RATE:
              if(!(val >= AL_CHORUS_MIN_RATE && val <= AL_CHORUS_MAX_RATE))
                  SETERR_RETURN(context, AL_INVALID_VALUE,, "Chorus rate out of range");
              props->Chorus.Rate = val;
              break;
  
          case AL_CHORUS_DEPTH:
              if(!(val >= AL_CHORUS_MIN_DEPTH && val <= AL_CHORUS_MAX_DEPTH))
                  SETERR_RETURN(context, AL_INVALID_VALUE,, "Chorus depth out of range");
              props->Chorus.Depth = val;
              break;
  
          case AL_CHORUS_FEEDBACK:
              if(!(val >= AL_CHORUS_MIN_FEEDBACK && val <= AL_CHORUS_MAX_FEEDBACK))
                  SETERR_RETURN(context, AL_INVALID_VALUE,, "Chorus feedback out of range");
              props->Chorus.Feedback = val;
              break;
  
          case AL_CHORUS_DELAY:
              if(!(val >= AL_CHORUS_MIN_DELAY && val <= AL_CHORUS_MAX_DELAY))
                  SETERR_RETURN(context, AL_INVALID_VALUE,, "Chorus delay out of range");
              props->Chorus.Delay = val;
              break;
  
          default:
              context->setError(AL_INVALID_ENUM, "Invalid chorus float property 0x%04x", param);
      }
  }
  void Chorus_setParamfv(EffectProps *props, ALCcontext *context, ALenum param, const ALfloat *vals)
  { Chorus_setParamf(props, context, param, vals[0]); }
  
  void Chorus_getParami(const EffectProps *props, ALCcontext *context, ALenum param, ALint *val)
  {
      switch(param)
      {
          case AL_CHORUS_WAVEFORM:
              *val = props->Chorus.Waveform;
              break;
  
          case AL_CHORUS_PHASE:
              *val = props->Chorus.Phase;
              break;
  
          default:
              context->setError(AL_INVALID_ENUM, "Invalid chorus integer property 0x%04x", param);
      }
  }
  void Chorus_getParamiv(const EffectProps *props, ALCcontext *context, ALenum param, ALint *vals)
  { Chorus_getParami(props, context, param, vals); }
  void Chorus_getParamf(const EffectProps *props, ALCcontext *context, ALenum param, ALfloat *val)
  {
      switch(param)
      {
          case AL_CHORUS_RATE:
              *val = props->Chorus.Rate;
              break;
  
          case AL_CHORUS_DEPTH:
              *val = props->Chorus.Depth;
              break;
  
          case AL_CHORUS_FEEDBACK:
              *val = props->Chorus.Feedback;
              break;
  
          case AL_CHORUS_DELAY:
              *val = props->Chorus.Delay;
              break;
  
          default:
              context->setError(AL_INVALID_ENUM, "Invalid chorus float property 0x%04x", param);
      }
  }
  void Chorus_getParamfv(const EffectProps *props, ALCcontext *context, ALenum param, ALfloat *vals)
  { Chorus_getParamf(props, context, param, vals); }
  
  DEFINE_ALEFFECT_VTABLE(Chorus);
  
  
  struct ChorusStateFactory final : public EffectStateFactory {
      EffectState *create() override { return new ChorusState{}; }
      EffectProps getDefaultProps() const noexcept override;
      const EffectVtable *getEffectVtable() const noexcept override { return &Chorus_vtable; }
  };
  
  EffectProps ChorusStateFactory::getDefaultProps() const noexcept
  {
      EffectProps props{};
      props.Chorus.Waveform = AL_CHORUS_DEFAULT_WAVEFORM;
      props.Chorus.Phase = AL_CHORUS_DEFAULT_PHASE;
      props.Chorus.Rate = AL_CHORUS_DEFAULT_RATE;
      props.Chorus.Depth = AL_CHORUS_DEFAULT_DEPTH;
      props.Chorus.Feedback = AL_CHORUS_DEFAULT_FEEDBACK;
      props.Chorus.Delay = AL_CHORUS_DEFAULT_DELAY;
      return props;
  }
  
  
  void Flanger_setParami(EffectProps *props, ALCcontext *context, ALenum param, ALint val)
  {
      switch(param)
      {
          case AL_FLANGER_WAVEFORM:
              if(!(val >= AL_FLANGER_MIN_WAVEFORM && val <= AL_FLANGER_MAX_WAVEFORM))
                  SETERR_RETURN(context, AL_INVALID_VALUE,, "Invalid flanger waveform");
              props->Chorus.Waveform = val;
              break;
  
          case AL_FLANGER_PHASE:
              if(!(val >= AL_FLANGER_MIN_PHASE && val <= AL_FLANGER_MAX_PHASE))
                  SETERR_RETURN(context, AL_INVALID_VALUE,, "Flanger phase out of range");
              props->Chorus.Phase = val;
              break;
  
          default:
              context->setError(AL_INVALID_ENUM, "Invalid flanger integer property 0x%04x", param);
      }
  }
  void Flanger_setParamiv(EffectProps *props, ALCcontext *context, ALenum param, const ALint *vals)
  { Flanger_setParami(props, context, param, vals[0]); }
  void Flanger_setParamf(EffectProps *props, ALCcontext *context, ALenum param, ALfloat val)
  {
      switch(param)
      {
          case AL_FLANGER_RATE:
              if(!(val >= AL_FLANGER_MIN_RATE && val <= AL_FLANGER_MAX_RATE))
                  SETERR_RETURN(context, AL_INVALID_VALUE,, "Flanger rate out of range");
              props->Chorus.Rate = val;
              break;
  
          case AL_FLANGER_DEPTH:
              if(!(val >= AL_FLANGER_MIN_DEPTH && val <= AL_FLANGER_MAX_DEPTH))
                  SETERR_RETURN(context, AL_INVALID_VALUE,, "Flanger depth out of range");
              props->Chorus.Depth = val;
              break;
  
          case AL_FLANGER_FEEDBACK:
              if(!(val >= AL_FLANGER_MIN_FEEDBACK && val <= AL_FLANGER_MAX_FEEDBACK))
                  SETERR_RETURN(context, AL_INVALID_VALUE,, "Flanger feedback out of range");
              props->Chorus.Feedback = val;
              break;
  
          case AL_FLANGER_DELAY:
              if(!(val >= AL_FLANGER_MIN_DELAY && val <= AL_FLANGER_MAX_DELAY))
                  SETERR_RETURN(context, AL_INVALID_VALUE,, "Flanger delay out of range");
              props->Chorus.Delay = val;
              break;
  
          default:
              context->setError(AL_INVALID_ENUM, "Invalid flanger float property 0x%04x", param);
      }
  }
  void Flanger_setParamfv(EffectProps *props, ALCcontext *context, ALenum param, const ALfloat *vals)
  { Flanger_setParamf(props, context, param, vals[0]); }
  
  void Flanger_getParami(const EffectProps *props, ALCcontext *context, ALenum param, ALint *val)
  {
      switch(param)
      {
          case AL_FLANGER_WAVEFORM:
              *val = props->Chorus.Waveform;
              break;
  
          case AL_FLANGER_PHASE:
              *val = props->Chorus.Phase;
              break;
  
          default:
              context->setError(AL_INVALID_ENUM, "Invalid flanger integer property 0x%04x", param);
      }
  }
  void Flanger_getParamiv(const EffectProps *props, ALCcontext *context, ALenum param, ALint *vals)
  { Flanger_getParami(props, context, param, vals); }
  void Flanger_getParamf(const EffectProps *props, ALCcontext *context, ALenum param, ALfloat *val)
  {
      switch(param)
      {
          case AL_FLANGER_RATE:
              *val = props->Chorus.Rate;
              break;
  
          case AL_FLANGER_DEPTH:
              *val = props->Chorus.Depth;
              break;
  
          case AL_FLANGER_FEEDBACK:
              *val = props->Chorus.Feedback;
              break;
  
          case AL_FLANGER_DELAY:
              *val = props->Chorus.Delay;
              break;
  
          default:
              context->setError(AL_INVALID_ENUM, "Invalid flanger float property 0x%04x", param);
      }
  }
  void Flanger_getParamfv(const EffectProps *props, ALCcontext *context, ALenum param, ALfloat *vals)
  { Flanger_getParamf(props, context, param, vals); }
  
  DEFINE_ALEFFECT_VTABLE(Flanger);
  
  
  /* Flanger is basically a chorus with a really short delay. They can both use
   * the same processing functions, so piggyback flanger on the chorus functions.
   */
  struct FlangerStateFactory final : public EffectStateFactory {
      EffectState *create() override { return new ChorusState{}; }
      EffectProps getDefaultProps() const noexcept override;
      const EffectVtable *getEffectVtable() const noexcept override { return &Flanger_vtable; }
  };
  
  EffectProps FlangerStateFactory::getDefaultProps() const noexcept
  {
      EffectProps props{};
      props.Chorus.Waveform = AL_FLANGER_DEFAULT_WAVEFORM;
      props.Chorus.Phase = AL_FLANGER_DEFAULT_PHASE;
      props.Chorus.Rate = AL_FLANGER_DEFAULT_RATE;
      props.Chorus.Depth = AL_FLANGER_DEFAULT_DEPTH;
      props.Chorus.Feedback = AL_FLANGER_DEFAULT_FEEDBACK;
      props.Chorus.Delay = AL_FLANGER_DEFAULT_DELAY;
      return props;
  }
  
  } // namespace
  
  EffectStateFactory *ChorusStateFactory_getFactory()
  {
      static ChorusStateFactory ChorusFactory{};
      return &ChorusFactory;
  }
  
  EffectStateFactory *FlangerStateFactory_getFactory()
  {
      static FlangerStateFactory FlangerFactory{};
      return &FlangerFactory;
  }
  