mayhem-firmware/firmware/baseband/proc_ert.cpp

/*
 * 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 "proc_ert.hpp"

#include "portapack_shared_memory.hpp"

#include "event_m4.hpp"

float ERTProcessor::abs(const complex8_t& v) {
    // const int16_t r = v.real() - offset_i;
    // const int16_t i = v.imag() - offset_q;
    // const uint32_t r2 = r * r;
    // const uint32_t i2 = i * i;
    // const uint32_t r2_i2 = r2 + i2;
    // return std::sqrt(static_cast<float>(r2_i2));
    const float r = static_cast<float>(v.real()) - offset_i;
    const float i = static_cast<float>(v.imag()) - offset_q;
    const float r2 = r * r;
    const float i2 = i * i;
    const float r2_i2 = r2 + i2;
    return std::sqrt(r2_i2);
}

void ERTProcessor::execute(const buffer_c8_t& buffer) {
    /* 4.194304MHz, 2048 samples */

    const complex8_t* src = &buffer.p[0];
    const complex8_t* const src_end = &buffer.p[buffer.count];

    average_i += src->real();
    average_q += src->imag();
    average_count++;
    if (average_count == average_window) {
        offset_i = static_cast<float>(average_i) / average_window;
        offset_q = static_cast<float>(average_q) / average_window;
        average_i = 0;
        average_q = 0;
        average_count = 0;
    }

    const float gain = 128 * samples_per_symbol;
    const float k = 1.0f / gain;

    while (src < src_end) {
        float sum = 0.0f;
        for (size_t i = 0; i < (samples_per_symbol / 2); i++) {
            sum += abs(*(src++));
        }
        sum_half_period[1] = sum_half_period[0];
        sum_half_period[0] = sum;

        sum_period[2] = sum_period[1];
        sum_period[1] = sum_period[0];
        sum_period[0] = (sum_half_period[0] + sum_half_period[1]) * k;

        manchester[2] = manchester[1];
        manchester[1] = manchester[0];
        manchester[0] = sum_period[2] - sum_period[0];

        const auto data = manchester[0] - manchester[2];

        clock_recovery(data);
    }
}

void ERTProcessor::consume_symbol(
    const float raw_symbol) {
    const uint_fast8_t sliced_symbol = (raw_symbol >= 0.0f) ? 1 : 0;
    scm_builder.execute(sliced_symbol);
    scmplus_builder.execute(sliced_symbol);
    idm_builder.execute(sliced_symbol);
}

void ERTProcessor::scm_handler(
    const baseband::Packet& packet) {
    const ERTPacketMessage message{ert::Packet::Type::SCM, packet};
    shared_memory.application_queue.push(message);
}

void ERTProcessor::scmplus_handler(
    const baseband::Packet& packet) {
    const ERTPacketMessage message{ert::Packet::Type::SCMPLUS, packet};
    shared_memory.application_queue.push(message);
}

void ERTProcessor::idm_handler(
    const baseband::Packet& packet) {
    const ERTPacketMessage message{ert::Packet::Type::IDM, packet};
    shared_memory.application_queue.push(message);
}

int main() {
    EventDispatcher event_dispatcher{std::make_unique<ERTProcessor>()};
    event_dispatcher.run();
    return 0;
}