portapack-mayhem/firmware/baseband/spectrum_collector.cpp

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/*
* Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
*
* 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 "spectrum_collector.hpp"
#include "dsp_fft.hpp"
#include "utility.hpp"
#include "event_m4.hpp"
#include "portapack_shared_memory.hpp"
#include <algorithm>
void SpectrumCollector::on_message(const Message* const message) {
switch (message->id) {
case Message::ID::UpdateSpectrum:
update();
break;
case Message::ID::SpectrumStreamingConfig:
set_state(*reinterpret_cast<const SpectrumStreamingConfigMessage*>(message));
break;
default:
break;
}
}
void SpectrumCollector::set_state(const SpectrumStreamingConfigMessage& message) {
if (message.mode == SpectrumStreamingConfigMessage::Mode::Running) {
start();
} else {
stop();
}
}
void SpectrumCollector::start() {
streaming = true;
ChannelSpectrumConfigMessage message{&fifo};
shared_memory.application_queue.push(message);
}
void SpectrumCollector::stop() {
streaming = false;
fifo.reset_in();
}
void SpectrumCollector::set_decimation_factor(
const size_t decimation_factor) {
channel_spectrum_decimator.set_factor(decimation_factor);
}
/* TODO: Refactor to register task with idle thread?
* It's sad that the idle thread has to call all the way back here just to
* perform the deferred task on the buffer of data we prepared.
*/
void SpectrumCollector::feed(
const buffer_c16_t& channel,
const int32_t filter_low_frequency,
const int32_t filter_high_frequency,
const int32_t filter_transition) {
// Called from baseband processing thread.
channel_filter_low_frequency = filter_low_frequency;
channel_filter_high_frequency = filter_high_frequency;
channel_filter_transition = filter_transition;
channel_spectrum_decimator.feed(
channel,
[this](const buffer_c16_t& data) {
this->post_message(data);
});
}
void SpectrumCollector::post_message(const buffer_c16_t& data) {
// Called from baseband processing thread.
if (streaming && !channel_spectrum_request_update) {
fft_swap(data, channel_spectrum);
channel_spectrum_sampling_rate = data.sampling_rate;
channel_spectrum_request_update = true;
EventDispatcher::events_flag(EVT_MASK_SPECTRUM);
}
}
template <typename T>
static typename T::value_type spectrum_window_none(const T& s, const size_t i) {
constexpr size_t length = sizeof(s) / sizeof(s[0]);
static_assert(power_of_two(length), "Array length must be power of 2");
return s[i];
};
template <typename T>
static typename T::value_type spectrum_window_hamming_3(const T& s, const size_t i) {
constexpr size_t length = sizeof(s) / sizeof(s[0]);
static_assert((length), "Array length must be power of 2");
constexpr size_t mask = length - 1;
// Three point Hamming window.
return s[i] * 0.54f + (s[(i - 1) & mask] + s[(i + 1) & mask]) * -0.23f;
};
template <typename T>
static typename T::value_type spectrum_window_blackman_3(const T& s, const size_t i) {
constexpr size_t length = sizeof(s) / sizeof(s[0]);
static_assert(power_of_two(length), "Array length must be power of 2");
constexpr size_t mask = length - 1;
// Three term Blackman window.
constexpr float alpha = 0.42f;
constexpr float beta = 0.5f * 0.5f;
constexpr float gamma = 0.08f * 0.05f;
return s[i] * alpha - (s[(i - 1) & mask] + s[(i + 1) & mask]) * beta + (s[(i - 2) & mask] + s[(i + 2) & mask]) * gamma;
};
void SpectrumCollector::update() {
// Called from idle thread (after EVT_MASK_SPECTRUM is flagged)
if (streaming && channel_spectrum_request_update) {
/* Decimated buffer is full. Compute spectrum. */
fft_c_preswapped(channel_spectrum, 0, 8);
ChannelSpectrum spectrum;
spectrum.sampling_rate = channel_spectrum_sampling_rate;
spectrum.channel_filter_low_frequency = channel_filter_low_frequency;
spectrum.channel_filter_high_frequency = channel_filter_high_frequency;
spectrum.channel_filter_transition = channel_filter_transition;
for (size_t i = 0; i < spectrum.db.size(); i++) {
const auto corrected_sample = spectrum_window_hamming_3(channel_spectrum, i);
const auto mag2 = magnitude_squared(corrected_sample * (1.0f / 32768.0f));
const float db = mag2_to_dbv_norm(mag2);
constexpr float mag_scale = 5.0f;
const unsigned int v = (db * mag_scale) + 255.0f;
spectrum.db[i] = std::max(0U, std::min(255U, v));
}
fifo.in(spectrum);
}
channel_spectrum_request_update = false;
}