js8call/JS8_Mode/Detector.cpp

/**
 * @file Detector.cpp
 * @brief Implementation of Detector class
 * Output device that distributes data in predefined chunks via a signal
 */

#include "Detector.h"
#include "JS8_Include/commons.h"
#include "JS8_Main/DriftingDateTime.h"

#include <QDateTime>
#include <QLoggingCategory>
#include <QMutexLocker>
#include <QtAlgorithms>

#include <algorithm>
#include <cmath>

/******************************************************************************/
// FIR Filter Coefficients
/******************************************************************************/

namespace {
// Filter coefficients for an FIR lowpass filter designed using ScopeFIR.
//
//   fsample     = 48000 Hz
//   Ntaps       = 49
//   fc          = 4500  Hz
//   fstop       = 6000  Hz
//   Ripple      = 1     dB
//   Stop Atten  = 40    dB
//   fout        = 12000 Hz

constexpr std::array LOWPASS{
    0.000861074040f,  0.010051920210f,  0.010161983649f,  0.011363155076f,
    0.008706594219f,  0.002613872664f,  -0.005202883094f, -0.011720748164f,
    -0.013752163325f, -0.009431602741f, 0.000539063909f,  0.012636767098f,
    0.021494659597f,  0.021951235065f,  0.011564169382f,  -0.007656470131f,
    -0.028965787341f, -0.042637874109f, -0.039203309748f, -0.013153301537f,
    0.034320769178f,  0.094717832646f,  0.154224604789f,  0.197758325022f,
    0.213715139513f,  0.197758325022f,  0.154224604789f,  0.094717832646f,
    0.034320769178f,  -0.013153301537f, -0.039203309748f, -0.042637874109f,
    -0.028965787341f, -0.007656470131f, 0.011564169382f,  0.021951235065f,
    0.021494659597f,  0.012636767098f,  0.000539063909f,  -0.009431602741f,
    -0.013752163325f, -0.011720748164f, -0.005202883094f, 0.002613872664f,
    0.008706594219f,  0.011363155076f,  0.010161983649f,  0.010051920210f,
    0.000861074040f};
} // namespace

/******************************************************************************/
// Implementation
/******************************************************************************/

#include "moc_Detector.cpp"

Q_DECLARE_LOGGING_CATEGORY(detector_js8)

/**
 * @brief Construct a new Detector object
 *
 * @param frameRate
 * @param periodLengthInSeconds
 * @param parent
 */
Detector::Detector(unsigned frameRate, unsigned periodLengthInSeconds,
                   QObject *parent)
    : AudioDevice(parent), m_frameRate(frameRate),
      m_period(periodLengthInSeconds), m_filter(LOWPASS) {
    clear();
}

/**
 * @brief Set the block size for FFT processing
 *
 * @param n
 */
void Detector::setBlockSize(unsigned n) { m_samplesPerFFT = n; }

/**
 * @brief Reset the detector state
 *
 * @return true
 * @return false
 */
bool Detector::reset() {
    clear();
    // don't call base call reset because it calls seek(0) which causes
    // a warning
    return isOpen();
}

/**
 * @brief Clear the detector buffer
 *
 */
void Detector::clear() {
#if JS8_RING_BUFFER
    resetBufferPosition();
    resetBufferContent();
#else
    dec_data.params.kin = 0;
    m_bufferPos = 0;
#endif

    // fill buffer with zeros (G4WJS commented out because it might cause
    // decoder hangs) qFill (dec_data.d2, dec_data.d2 + sizeof (dec_data.d2) /
    // sizeof (dec_data.d2[0]), 0);
}

/**
 * @brief Reset the buffer position based on current time
 *
 */
void Detector::resetBufferPosition() {
    QMutexLocker mutex(&m_lock);

    // set index to roughly where we are in time (1ms resolution)
    qint64 const now = DriftingDateTime::currentMSecsSinceEpoch();
    unsigned const msInPeriod = (now % 86400000LL) % (m_period * 1000);
    int const prevKin = dec_data.params.kin;

    dec_data.params.kin = qMin(
        (msInPeriod * m_frameRate) / 1000,
        static_cast<unsigned>(sizeof(dec_data.d2) / sizeof(dec_data.d2[0])));
    m_bufferPos = 0;
    m_ns = secondInPeriod();

    int const delta = dec_data.params.kin - prevKin;

    qCDebug(detector_js8) << "advancing detector buffer from" << prevKin << "to"
                          << dec_data.params.kin << "delta" << delta;

    // rotate buffer moving the contents that were at prevKin to the new kin
    // position
    if (delta < 0) {
        std::rotate(std::begin(dec_data.d2), std::begin(dec_data.d2) - delta,
                    std::end(dec_data.d2));
    } else {
        std::rotate(std::rbegin(dec_data.d2), std::rbegin(dec_data.d2) + delta,
                    std::rend(dec_data.d2));
    }
}

/**
 * @brief Reset the buffer content to zero
 *
 */
void Detector::resetBufferContent() {
    QMutexLocker mutex(&m_lock);

    std::fill(std::begin(dec_data.d2), std::end(dec_data.d2), 0);
    qCDebug(detector_js8) << "clearing detector buffer content";
}

/**
 * @brief Write data to the detector buffer
 *
 * @param data
 * @param maxSize
 * @return qint64
 */
qint64 Detector::writeData(char const *const data, qint64 const maxSize) {
    QMutexLocker mutex(&m_lock);

    // When ns has wrapped around to zero, restart the buffers.

    int const ns = secondInPeriod();
    if (ns < m_ns) {
        dec_data.params.kin = 0;
        m_bufferPos = 0;
    }
    m_ns = ns;

    // No torn frames.

    Q_ASSERT(!(maxSize % static_cast<qint64>(bytesPerFrame())));

    // These are in terms of input frames (not down sampled).

    size_t const framesAcceptable =
        (sizeof(dec_data.d2) / sizeof(dec_data.d2[0]) - dec_data.params.kin) *
        Filter::NDOWN;
    size_t const framesAccepted =
        qMin(static_cast<size_t>(maxSize / bytesPerFrame()), framesAcceptable);

    if (framesAccepted < static_cast<size_t>(maxSize / bytesPerFrame())) {
        qCDebug(detector_js8)
            << "dropped " << maxSize / bytesPerFrame() - framesAccepted
            << " frames of data on the floor!" << dec_data.params.kin << ns;
    }

    for (auto remaining = framesAccepted; remaining;) {
        size_t const numFramesProcessed =
            qMin(m_samplesPerFFT * Filter::NDOWN - m_bufferPos, remaining);

        store(&data[(framesAccepted - remaining) * bytesPerFrame()],
              numFramesProcessed, &m_buffer[m_bufferPos]);

        m_bufferPos += numFramesProcessed;

        if (m_bufferPos == m_samplesPerFFT * Filter::NDOWN) {
            if (dec_data.params.kin >= 0 &&
                dec_data.params.kin <
                    static_cast<int>(JS8_NTMAX * 12000 - m_samplesPerFFT)) {
                for (std::size_t i = 0; i < m_samplesPerFFT; ++i) {
                    dec_data.d2[dec_data.params.kin++] =
                        m_filter.downSample(&m_buffer[i * Filter::NDOWN]);
                }
            }
            Q_EMIT framesWritten(dec_data.params.kin);
            m_bufferPos = 0;
        }
        remaining -= numFramesProcessed;
    }

    // We drop any data past the end of the buffer on the floor
    // until the next period starts

    return maxSize;
}

/**
 * @brief Get the current second in the period
 *
 * @return unsigned
 */
unsigned Detector::secondInPeriod() const {
    // we take the time of the data as the following assuming no latency
    // delivering it to us (not true but close enough for us)
    qint64 now(DriftingDateTime::currentMSecsSinceEpoch());
    unsigned secondInToday((now % 86400000LL) / 1000);
    return secondInToday % m_period;
}

/******************************************************************************/

Q_LOGGING_CATEGORY(detector_js8, "detector.js8", QtWarningMsg)