39 lines
1.2 KiB
C
39 lines
1.2 KiB
C
#ifndef FIXFFT_H
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#define FIXFFT_H
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//#include <WProgram.h> //depreacted included in arduino.h
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/*
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fix_fft() - perform forward/inverse fast Fourier transform.
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fr[n],fi[n] are real and imaginary arrays, both INPUT AND
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RESULT (in-place FFT), with 0 <= n < 2**m; set inverse to
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0 for forward transform (FFT), or 1 for iFFT.
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*/
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int fix_fft(char fr[], char fi[], int m, int inverse);
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/*
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fix_fftr() - forward/inverse FFT on array of real numbers.
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Real FFT/iFFT using half-size complex FFT by distributing
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even/odd samples into real/imaginary arrays respectively.
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In order to save data space (i.e. to avoid two arrays, one
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for real, one for imaginary samples), we proceed in the
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following two steps: a) samples are rearranged in the real
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array so that all even samples are in places 0-(N/2-1) and
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all imaginary samples in places (N/2)-(N-1), and b) fix_fft
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is called with fr and fi pointing to index 0 and index N/2
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respectively in the original array. The above guarantees
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that fix_fft "sees" consecutive real samples as alternating
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real and imaginary samples in the complex array.
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*/
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int fix_fftr(char f[], int m, int inverse);
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static inline char FIX_MPY(char a,char b);
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#endif
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