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https://github.com/AlexGyver/GyverLamp2.git
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73 lines
1.9 KiB
C
73 lines
1.9 KiB
C
#pragma once
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#define FFT_SIZE 64 // размер выборки (кратно степени 2)
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static float sinF[] = {0.0, -1.0, -0.707107, -0.382683, -0.195090, -0.098017, -0.049068, -0.024541, -0.012272, -0.006136};
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void FFT(int* AVal, int* FTvl) {
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int i, j, m, Mmax, Istp, count = 0;
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float Tmpr, Tmpi, Tmvl[FFT_SIZE * 2];
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float Wpr, Wr, Wi;
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for (i = 0; i < FFT_SIZE * 2; i += 2) {
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Tmvl[i] = 0;
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Tmvl[i + 1] = AVal[i / 2];
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}
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i = j = 1;
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while (i < FFT_SIZE * 2) {
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if (j > i) {
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Tmpr = Tmvl[i];
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Tmvl[i] = Tmvl[j];
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Tmvl[j] = Tmpr;
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Tmpr = Tmvl[i + 1];
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Tmvl[i + 1] = Tmvl[j + 1];
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Tmvl[j + 1] = Tmpr;
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}
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i = i + 2;
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m = FFT_SIZE;
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while ((m >= 2) && (j > m)) {
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j = j - m;
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m = m >> 1;
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}
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j = j + m;
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}
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Mmax = 2;
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while (FFT_SIZE * 2 > Mmax) {
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Wpr = sinF[count + 1] * sinF[count + 1] * 2;
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Istp = Mmax * 2;
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Wr = 1;
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Wi = 0;
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m = 1;
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while (m < Mmax) {
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i = m;
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m = m + 2;
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Tmpr = Wr;
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Tmpi = Wi;
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Wr += -Tmpr * Wpr - Tmpi * sinF[count];
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Wi += Tmpr * sinF[count] - Tmpi * Wpr;
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while (i < FFT_SIZE * 2) {
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j = i + Mmax;
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Tmpr = Wr * Tmvl[j] - Wi * Tmvl[j - 1];
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Tmpi = Wi * Tmvl[j] + Wr * Tmvl[j - 1];
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Tmvl[j] = Tmvl[i] - Tmpr;
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Tmvl[j - 1] = Tmvl[i - 1] - Tmpi;
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Tmvl[i] = Tmvl[i] + Tmpr;
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Tmvl[i - 1] = Tmvl[i - 1] + Tmpi;
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i = i + Istp;
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}
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}
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count++;
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Mmax = Istp;
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}
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for (i = 0; i < FFT_SIZE; i++) {
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j = i * 2;
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FTvl[i] = (int)(Tmvl[j] * Tmvl[j] + Tmvl[j + 1] * Tmvl[j + 1]) >> 18;
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}
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}
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// по мотивам https://ru.wikibooks.org/wiki/%D0%A0%D0%B5%D0%B0%D0%BB%D0%B8%D0%B7%D0%B0%D1%86%D0%B8%D0%B8_%D0%B0%D0%BB%D0%B3%D0%BE%D1%80%D0%B8%D1%82%D0%BC%D0%BE%D0%B2/%D0%91%D1%8B%D1%81%D1%82%D1%80%D0%BE%D0%B5_%D0%BF%D1%80%D0%B5%D0%BE%D0%B1%D1%80%D0%B0%D0%B7%D0%BE%D0%B2%D0%B0%D0%BD%D0%B8%D0%B5_%D0%A4%D1%83%D1%80%D1%8C%D0%B5
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