portapack-mayhem/firmware/baseband/dsp_goertzel.cpp
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/*
* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
* Copyright (C) 2018 Furrtek
*
* 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_goertzel.hpp"
#include "complex.hpp"
#include "sine_table.hpp"
namespace dsp {
GoertzelDetector::GoertzelDetector(
const float frequency,
const uint32_t sample_rate) {
coefficient = 2.0 * sin_f32((2.0 * pi * frequency / sample_rate) - pi / 2.0);
}
float GoertzelDetector::execute(
const buffer_s16_t& src) {
const size_t count = src.count;
for (size_t i = 0; i < count; i++) {
s[2] = s[1];
s[1] = s[0];
s[0] = src.p[i] + coefficient * s[1] - s[2];
}
const uint32_t sq0 = s[0] * s[0];
const uint32_t sq1 = s[1] * s[1];
float magnitude = __builtin_sqrtf(sq0 + sq1 - s[0] * s[1] * coefficient);
return magnitude;
}
} /* namespace dsp */