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/*
* TinyFFT.h
* ---------
* Purpose: A simple FFT implementation for power-of-two FFTs
* Notes : This is a C++ adaption of Ryuhei Mori's BSD 2-clause licensed TinyFFT
* available from https://github.com/ryuhei-mori/tinyfft
* Authors: Ryuhei Mori
* OpenMPT Devs
* The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
*/
#pragma once
#include "openmpt/all/BuildSettings.hpp"
#include <complex>
OPENMPT_NAMESPACE_BEGIN
class TinyFFT
{
static constexpr std::complex<double> I{0.0, 1.0};
std::vector<std::complex<double>> w; // Pre-computed twiddle factors
const uint32 k; // log2 of FFT size
void GenerateTwiddleFactors(uint32 i, uint32 b, std::complex<double> z);
public:
TinyFFT(const uint32 fftSize);
uint32 Size() const noexcept;
// Computes in-place FFT of size 2^k of A, result is in bit-reversed order.
void FFT(std::vector<std::complex<double>> &A) const;
// Computes in-place IFFT of size 2^k of A, input is expected to be in bit-reversed order.
void IFFT(std::vector<std::complex<double>> &A) const;
static void Normalize(std::vector<std::complex<double>> &data);
};
OPENMPT_NAMESPACE_END
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