83 lines
2.3 KiB
C++
83 lines
2.3 KiB
C++
#ifndef MENGA_FFT
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#define MENGA_FFT
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#include <valarray>
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#include <vector>
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#include "common.h"
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#include "cyclequeue.h"
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typedef std::complex<float> Complex;
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typedef std::valarray<Complex> CArray;
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namespace Mengu {
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namespace dsp {
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using namespace std;
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class SFT {
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// Slow O(N^2) Fourier Transform
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public:
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// SFT();
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// out-of-place ft
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vector<Complex> perform(const vector<Complex> &input);
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private:
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vector<Complex> _es;
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// vector<Complex> _sines;
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};
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class FFTBuffer; // foward declaration
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class FFT {
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public:
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// Fast Fourier transform that uses lookup tables and performs onto an established array
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// Only works for arrays of a declared size. Designed to be cached and use many times
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// To use it for different sample rates/lengths, create a new FFT of a different size
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// The size needs to be a power of 2 in order for this to work properly
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FFT(uint32_t size);
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~FFT();
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// Both arrays must be at least as long as _size
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void transform(const Complex *input, Complex *output) const;
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void transform(const CycleQueue<Complex> &input, Complex *output) const; // to avoid having to reallocate array
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//unlike 'transform' this edits *input to avoid unnecissary memory allocation
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void inverse_transform(const Complex *input, Complex *output) const;
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const Complex *get_es() const;
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uint32_t size() const { return _size; }
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private:
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Complex *_es;
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uint32_t _size;
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uint32_t _fft_size; // size of arrays used in fft computations. must be a power of 2
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// cache buffers used in intermediate calculation
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Complex *_inp_vec;
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Complex *_out_vec;
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void _transform_rec(const Complex *input, Complex *output, const uint32_t N, const uint32_t stride) const;
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void _transform_rec(const CycleQueue<Complex> &input, uint32_t inp_ind, Complex *output, const uint32_t N, const uint32_t stride) const;
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friend class FFTBuffer;
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public:
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};
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class FFTBuffer {
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// class designed to do update a n FFT of a signal in real time
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public:
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void push_signal(const Complex *x, const uint32_t &size) {}
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// copies the last 'size'
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void pop_transformed_signal(const Complex *output, const uint32_t &size) {}
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private:
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CycleQueue<Complex> _buffer;
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};
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};
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};
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#endif |