portapack-mayhem/firmware/baseband/proc_pocsag.hpp

/*
 * Copyright (C) 1996 Thomas Sailer (sailer@ife.ee.ethz.ch, hb9jnx@hb9w.che.eu)
 * Copyright (C) 2012-2014 Elias Oenal (multimon-ng@eliasoenal.com)
 * Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
 * Copyright (C) 2016 Furrtek
 * Copyright (C) 2023 Kyle Reed
 *
 * 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.
 */

#ifndef __PROC_POCSAG_H__
#define __PROC_POCSAG_H__

#include "baseband_processor.hpp"
#include "baseband_thread.hpp"
#include "rssi_thread.hpp"

#include "dsp_decimate.hpp"
#include "dsp_demodulate.hpp"

#include "pocsag_packet.hpp"

#include "pocsag.hpp"
#include "message.hpp"
#include "audio_output.hpp"
#include "portapack_shared_memory.hpp"

#include <cstdint>
#include <bitset>
using namespace std;

// Class used to smooth demodulated waveform prior to decoding
// -----------------------------------------------------------
template <class ValType, class CalcType>
class SmoothVals {
   protected:
    ValType* m_lastVals;  // Previous N values
    int m_size;           // The size N
    CalcType m_sumVal;    // Running sum of lastVals
    int m_pos;            // Current position in last vals ring buffer
    int m_count;          //

   public:
    SmoothVals()
        : m_lastVals(NULL), m_size(1), m_sumVal(0), m_pos(0), m_count(0) {
        m_lastVals = new ValType[m_size];
    }

    // --------------------------------------------------
    // --------------------------------------------------
    virtual ~SmoothVals() {
        delete[] m_lastVals;
    }

    SmoothVals(const SmoothVals<float, float>&) {
    }

    SmoothVals& operator=(const SmoothVals<float, float>&) {
        return *this;
    }

    // --------------------------------------------------
    // Set size of smoothing
    // --------------------------------------------------
    void SetSize(int size) {
        m_size = std::max(size, 1);
        m_pos = 0;
        delete[] m_lastVals;
        m_lastVals = new ValType[m_size];
        m_sumVal = 0;
    }

    // --------------------------------------------------
    // Get size of smoothing
    // --------------------------------------------------
    int Size() { return m_size; }

    // --------------------------------------------------
    // In place processing
    // --------------------------------------------------
    void Process(ValType* valBuff, int numVals) {
        ValType tmpVal;

        if (m_count > (1024 * 10)) {
            // Recalculate the sum value occasionaly, stops accumulated errors when using float
            m_count = 0;
            m_sumVal = 0;
            for (int i = 0; i < m_size; ++i) {
                m_sumVal += (CalcType)m_lastVals[i];
            }
        }

        // Use a rolling smoothed value while processing the buffer
        for (int buffPos = 0; buffPos < numVals; ++buffPos) {
            m_pos++;
            if (m_pos >= m_size) {
                m_pos = 0;
            }

            m_sumVal -= (CalcType)m_lastVals[m_pos];  // Subtract the oldest value
            m_lastVals[m_pos] = valBuff[buffPos];     // Store the new value
            m_sumVal += (CalcType)m_lastVals[m_pos];  // Add on the new value

            tmpVal = (ValType)(m_sumVal / m_size);  // Scale by number of values smoothed
            valBuff[buffPos] = tmpVal;
        }

        m_count += numVals;
    }
};

// --------------------------------------------------
// Class to process base band data to pocsag frames
// --------------------------------------------------
class POCSAGProcessor : public BasebandProcessor {
   public:
    void execute(const buffer_c8_t& buffer) override;
    void on_message(const Message* const message) override;

    int OnDataFrame(int len, int baud);
    int OnDataWord(uint32_t word, int pos);

   private:
    static constexpr size_t baseband_fs = 3072000;
    static constexpr uint8_t stat_update_interval = 10;
    static constexpr uint32_t stat_update_threshold =
        baseband_fs / stat_update_interval;

    std::array<complex16_t, 512> dst{};
    const buffer_c16_t dst_buffer{
        dst.data(),
        dst.size()};
    std::array<float, 32> audio{};
    const buffer_f32_t audio_buffer{
        audio.data(),
        audio.size()};

    dsp::decimate::FIRC8xR16x24FS4Decim8 decim_0{};
    dsp::decimate::FIRC16xR16x32Decim8 decim_1{};
    dsp::decimate::FIRAndDecimateComplex channel_filter{};
    dsp::demodulate::FM demod{};
    SmoothVals<float, float> smooth = {};

    AudioOutput audio_output{};

    bool configured = false;
    pocsag::POCSAGPacket packet{};

    uint32_t samples_processed = 0;

    void configure();
    void send_stats() const;

    // ----------------------------------------
    // Frame extractraction methods and members
    // ----------------------------------------
    void initFrameExtraction();
    struct FIFOStruct {
        unsigned long codeword;
        int numBits;
    };

#define BIT_BUF_SIZE (64)

    void resetVals();
    void setFrameExtractParams(long a_samplesPerSec, long a_maxBaud = 8000, long a_minBaud = 200, long maxRunOfSameValue = 32);

    int processDemodulatedSamples(float* sampleBuff, int noOfSamples);
    int extractFrames();

    void storeBit();
    short getBit();

    int getNoOfBits();
    uint32_t getRate() const;

    uint32_t m_averageSymbolLen_1024{0};
    uint32_t m_lastStableSymbolLen_1024{0};

    uint32_t m_samplesPerSec{0};
    uint32_t m_goodTransitions{0};
    uint32_t m_badTransitions{0};

    uint32_t m_sampleNo{0};
    float m_sample{0};
    float m_valMid{0.0f};
    float m_lastSample{0.0f};

    uint32_t m_lastTransPos_1024{0};
    uint32_t m_lastSingleBitPos_1024{0};

    uint32_t m_nextBitPosInt{0};  // Integer rounded up version to save on ops
    uint32_t m_nextBitPos_1024{0};
    uint32_t m_lastBitPos_1024{0};

    uint32_t m_shortestGoodTrans_1024{0};
    uint32_t m_minSymSamples_1024{0};
    uint32_t m_maxSymSamples_1024{0};
    uint32_t m_maxRunOfSameValue{0};

    bitset<(size_t)BIT_BUF_SIZE> m_bits{0};
    long m_bitsStart{0};
    long m_bitsEnd{0};

    FIFOStruct m_fifo{0, 0};
    bool m_gotSync{false};
    int m_numCode{0};
    bool m_inverted{false};

    FMSquelch squelch_{};
    uint64_t squelch_history = 0;

    /* NB: Threads should be the last members in the class definition. */
    BasebandThread baseband_thread{baseband_fs, this, baseband::Direction::Receive};
    RSSIThread rssi_thread{};
};

#endif /*__PROC_POCSAG_H__*/