portapack-mayhem/firmware/test/baseband/dsp_fft_test.cpp

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/*
* Copyright (C) 2023 Bernd Herzog
*
* This file is part of PortaPack.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include "dsp_fft.hpp"
#include "doctest.h"
TEST_CASE("ifft successfully calculates dc on zero frequency") {
uint32_t fft_width = 8;
complex16_t* v = new complex16_t[fft_width];
complex16_t* tmp = new complex16_t[fft_width];
v[0] = {1024, 0}; // DC bin
v[1] = {0, 0};
v[2] = {0, 0};
v[3] = {0, 0};
v[4] = {0, 0};
v[5] = {0, 0};
v[6] = {0, 0};
v[7] = {0, 0};
ifft<complex16_t>(v, fft_width, tmp);
CHECK(v[0].real() == 1024);
CHECK(v[1].real() == 1024);
CHECK(v[2].real() == 1024);
CHECK(v[3].real() == 1024);
CHECK(v[4].real() == 1024);
CHECK(v[5].real() == 1024);
CHECK(v[6].real() == 1024);
CHECK(v[7].real() == 1024);
for (uint32_t i = 0; i < fft_width; i++)
CHECK(v[i].imag() == 0);
free(v);
free(tmp);
}
TEST_CASE("ifft successfully calculates pure sine of half the sample rate") {
uint32_t fft_width = 8;
complex16_t* v = new complex16_t[fft_width];
complex16_t* tmp = new complex16_t[fft_width];
v[0] = {0, 0};
v[1] = {0, 0};
v[2] = {0, 0};
v[3] = {0, 0};
v[4] = {1024, 0}; // sample rate /2 bin
v[5] = {0, 0};
v[6] = {0, 0};
v[7] = {0, 0};
ifft<complex16_t>(v, fft_width, tmp);
CHECK(v[0].real() == 1024);
CHECK(v[1].real() == -1024);
CHECK(v[2].real() == 1024);
CHECK(v[3].real() == -1024);
CHECK(v[4].real() == 1024);
CHECK(v[5].real() == -1024);
CHECK(v[6].real() == 1024);
CHECK(v[7].real() == -1024);
for (uint32_t i = 0; i < fft_width; i++)
CHECK(v[i].imag() == 0);
free(v);
free(tmp);
}