VectorFFT.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "DSP/FFTAlgorithm.h"
#include "DSP/BufferVectorOperations.h"
 
namespace Audio
{
    // Forward declaration
    class FVectorComplexFFT;
 
    class FVectorRealToComplexFFT : public IFFTAlgorithm
    {
        public:
            static const int32 MinLog2FFTSize;
 
            static const int32 MaxLog2FFTSize;
 
            FVectorRealToComplexFFT(int32 InLog2Size);
 
            virtual ~FVectorRealToComplexFFT();
 
            virtual int32 Size() const override;
 
            virtual EFFTScaling ForwardScaling() const override;
 
            virtual EFFTScaling InverseScaling() const override;
 
            
            virtual void ForwardRealToComplex(const float* RESTRICT InReal, float* RESTRICT OutComplex) override;
 
            virtual void InverseComplexToReal(const float* RESTRICT InComplex, float* RESTRICT OutReal) override;
 
            virtual void BatchForwardRealToComplex(int32 InCount, const float* const RESTRICT InReal[], float* RESTRICT OutComplex[]) override;
 
            virtual void BatchInverseComplexToReal(int32 InCount, const float* const RESTRICT InComplex[], float* RESTRICT OutReal[]) override;
 
        private:
 
            // Needed to convert buffers for implementation of real-to-complex fft using complex-to-comlex fft.
            struct FConversionBuffers
            {
                FAlignedFloatBuffer AlphaReal;
                FAlignedFloatBuffer AlphaImag;
                FAlignedFloatBuffer BetaReal;
                FAlignedFloatBuffer BetaImag;
            };
 
 
            // Initializes conversion buffers
            void InitRealSequenceConversionBuffers();
 
            // Converts a buffer
            void ConvertSequence(const FConversionBuffers& InBuffers, const float* RESTRICT InValues, int32 InStartIndex, float* RESTRICT OutValues);
 
            int32 FFTSize;
            int32 Log2FFTSize;
 
            FAlignedFloatBuffer WorkBuffer;
 
            FConversionBuffers ForwardConvBuffers;
            FConversionBuffers InverseConvBuffers;
 
            // Complex FFT implementation.
            TUniquePtr<FVectorComplexFFT> ComplexFFT;
    };
 
    class FVectorFFTFactory : public IFFTAlgorithmFactory
    {
        public:
            virtual ~FVectorFFTFactory();
 
            virtual FName GetFactoryName() const override;
 
            virtual bool IsHardwareAccelerated() const override;
 
            virtual bool Expects128BitAlignedArrays() const override;
 
            virtual bool AreFFTSettingsSupported(const FFFTSettings& InSettings) const override;
 
            virtual TUniquePtr<IFFTAlgorithm> NewFFTAlgorithm(const FFFTSettings& InSettings) override;
    };
}