/*
   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Her Majesty
   the Queen in Right of Canada (Communications Research Center Canada)

   Copyright (C) 2024
   Matthias P. Braendli, matthias.braendli@mpb.li

    http://opendigitalradio.org
 */
/*
   This file is part of ODR-DabMod.

   ODR-DabMod 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 3 of the
   License, or (at your option) any later version.

   ODR-DabMod 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 ODR-DabMod.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "OfdmGenerator.h"
#include "PcDebug.h"

#include <stdexcept>
#include <assert.h>
#include <string>
#include <numeric>
#include <vector>
#include <cstring>
#include <complex>

static const size_t MAX_CLIP_STATS = 10;

using FFTW_TYPE = fftwf_complex;

OfdmGeneratorCF32::OfdmGeneratorCF32(size_t nbSymbols,
                             size_t nbCarriers,
                             size_t spacing,
                             bool& enableCfr,
                             float& cfrClip,
                             float& cfrErrorClip,
                             bool inverse) :
    ModCodec(), RemoteControllable("ofdm"),
    myFftPlan(nullptr),
    myFftIn(nullptr), myFftOut(nullptr),
    myNbSymbols(nbSymbols),
    myNbCarriers(nbCarriers),
    mySpacing(spacing),
    myCfr(enableCfr),
    myCfrClip(cfrClip),
    myCfrErrorClip(cfrErrorClip),
    myCfrFft(nullptr),
    // Initialise the PAPRStats to a few seconds worth of samples
    myPaprBeforeCFR(nbSymbols * 50),
    myPaprAfterCFR(nbSymbols * 50)
{
    PDEBUG("OfdmGenerator::OfdmGenerator(%zu, %zu, %zu, %s) @ %p\n",
            nbSymbols, nbCarriers, spacing, inverse ? "true" : "false", this);

    if (nbCarriers > spacing) {
        throw std::runtime_error("OfdmGenerator nbCarriers > spacing!");
    }

    /* register the parameters that can be remote controlled */
    RC_ADD_PARAMETER(cfr, "Enable crest factor reduction");
    RC_ADD_PARAMETER(clip, "CFR: Clip to amplitude");
    RC_ADD_PARAMETER(errorclip, "CFR: Limit error");
    RC_ADD_PARAMETER(clip_stats, "CFR: statistics (clip ratio, errorclip ratio)");
    RC_ADD_PARAMETER(papr, "PAPR measurements (before CFR, after CFR)");

    if (inverse) {
        myPosDst = (nbCarriers & 1 ? 0 : 1);
        myPosSrc = 0;
        myPosSize = (nbCarriers + 1) / 2;
        myNegDst = spacing - (nbCarriers / 2);
        myNegSrc = (nbCarriers + 1) / 2;
        myNegSize = nbCarriers / 2;
    }
    else {
        myPosDst = (nbCarriers & 1 ? 0 : 1);
        myPosSrc = nbCarriers / 2;
        myPosSize = (nbCarriers + 1) / 2;
        myNegDst = spacing - (nbCarriers / 2);
        myNegSrc = 0;
        myNegSize = nbCarriers / 2;
    }
    myZeroDst = myPosDst + myPosSize;
    myZeroSize = myNegDst - myZeroDst;

    PDEBUG("  myPosDst: %u\n", myPosDst);
    PDEBUG("  myPosSrc: %u\n", myPosSrc);
    PDEBUG("  myPosSize: %u\n", myPosSize);
    PDEBUG("  myNegDst: %u\n", myNegDst);
    PDEBUG("  myNegSrc: %u\n", myNegSrc);
    PDEBUG("  myNegSize: %u\n", myNegSize);
    PDEBUG("  myZeroDst: %u\n", myZeroDst);
    PDEBUG("  myZeroSize: %u\n", myZeroSize);

    const int N = mySpacing; // The size of the FFT
    myFftIn = (FFTW_TYPE*)fftwf_malloc(sizeof(FFTW_TYPE) * N);
    myFftOut = (FFTW_TYPE*)fftwf_malloc(sizeof(FFTW_TYPE) * N);
    fftwf_set_timelimit(2);
    myFftPlan = fftwf_plan_dft_1d(N,
            myFftIn, myFftOut,
            FFTW_BACKWARD, FFTW_MEASURE);

    myCfrPostClip = (FFTW_TYPE*)fftwf_malloc(sizeof(FFTW_TYPE) * N);
    myCfrPostFft = (FFTW_TYPE*)fftwf_malloc(sizeof(FFTW_TYPE) * N);
    myCfrFft = fftwf_plan_dft_1d(N,
            myCfrPostClip, myCfrPostFft,
            FFTW_FORWARD, FFTW_MEASURE);

    if (sizeof(complexf) != sizeof(FFTW_TYPE)) {
        printf("sizeof(complexf) %zu\n", sizeof(complexf));
        printf("sizeof(FFT_TYPE) %zu\n", sizeof(FFTW_TYPE));
        throw std::runtime_error(
                "OfdmGenerator::process complexf size is not FFT_TYPE size!");
    }
}


OfdmGeneratorCF32::~OfdmGeneratorCF32()
{
    PDEBUG("OfdmGenerator::~OfdmGenerator() @ %p\n", this);

    if (myFftIn) {
         fftwf_free(myFftIn);
    }

    if (myFftOut) {
         fftwf_free(myFftOut);
    }

    if (myFftPlan) {
        fftwf_destroy_plan(myFftPlan);
    }

    if (myCfrPostClip) {
        fftwf_free(myCfrPostClip);
    }

    if (myCfrPostFft) {
        fftwf_free(myCfrPostFft);
    }

    if (myCfrFft) {
        fftwf_destroy_plan(myCfrFft);
    }
}

int OfdmGeneratorCF32::process(Buffer* const dataIn, Buffer* dataOut)
{
    PDEBUG("OfdmGenerator::process(dataIn: %p, dataOut: %p)\n",
            dataIn, dataOut);

    dataOut->setLength(myNbSymbols * mySpacing * sizeof(complexf));

    FFTW_TYPE *in = reinterpret_cast<FFTW_TYPE*>(dataIn->getData());
    FFTW_TYPE *out = reinterpret_cast<FFTW_TYPE*>(dataOut->getData());

    size_t sizeIn = dataIn->getLength() / sizeof(complexf);
    size_t sizeOut = dataOut->getLength() / sizeof(complexf);

    if (sizeIn != myNbSymbols * myNbCarriers) {
        PDEBUG("Nb symbols: %zu\n", myNbSymbols);
        PDEBUG("Nb carriers: %zu\n", myNbCarriers);
        PDEBUG("Spacing: %zu\n", mySpacing);
        PDEBUG("\n%zu != %zu\n", sizeIn, myNbSymbols * myNbCarriers);
        throw std::runtime_error(
                "OfdmGenerator::process input size not valid!");
    }
    if (sizeOut != myNbSymbols * mySpacing) {
        PDEBUG("Nb symbols: %zu\n", myNbSymbols);
        PDEBUG("Nb carriers: %zu\n", myNbCarriers);
        PDEBUG("Spacing: %zu\n", mySpacing);
        PDEBUG("\n%zu != %zu\n", sizeIn, myNbSymbols * mySpacing);
        throw std::runtime_error(
                "OfdmGenerator::process output size not valid!");
    }

    // It is not guaranteed that fftw keeps the FFT input vector intact.
    // That's why we copy it to the reference.
    std::vector<complexf> reference;

    // IFFT output before CFR applied, for MER calc
    std::vector<complexf> before_cfr;

    size_t num_clip = 0;
    size_t num_error_clip = 0;

    // For performance reasons, do not calculate MER for every symbol.
    myMERCalcIndex = (myMERCalcIndex + 1) % myNbSymbols;

    // The PAPRStats' clear() is not threadsafe, do not access it
    // from the RC functions.
    if (myPaprClearRequest.exchange(false)) {
        myPaprBeforeCFR.clear();
        myPaprAfterCFR.clear();
    }

    for (size_t i = 0; i < myNbSymbols; i++) {
        myFftIn[0][0] = 0;
        myFftIn[0][1] = 0;

        /* For TM I this is:
         * ZeroDst=769 ZeroSize=511
         * PosSrc=0 PosDst=1 PosSize=768
         * NegSrc=768 NegDst=1280 NegSize=768
         */
        memset(&myFftIn[myZeroDst], 0, myZeroSize * sizeof(FFTW_TYPE));
        memcpy(&myFftIn[myPosDst], &in[myPosSrc],
                myPosSize * sizeof(FFTW_TYPE));
        memcpy(&myFftIn[myNegDst], &in[myNegSrc],
                myNegSize * sizeof(FFTW_TYPE));


        if (myCfr) {
            reference.resize(mySpacing);
            memcpy(reinterpret_cast<fftwf_complex*>(reference.data()),
                    myFftIn, mySpacing * sizeof(FFTW_TYPE));
        }

        fftwf_execute(myFftPlan); // IFFT from myFftIn to myFftOut

        
        if (myCfr) {
            complexf *symbol = reinterpret_cast<complexf*>(myFftOut);
            myPaprBeforeCFR.process_block(symbol, mySpacing);

            if (myMERCalcIndex == i) {
                before_cfr.resize(mySpacing);
                memcpy(reinterpret_cast<fftwf_complex*>(before_cfr.data()),
                        myFftOut, mySpacing * sizeof(FFTW_TYPE));
            }

            /* cfr_one_iteration runs the myFftPlan again at the end, and
             * therefore writes the output data to myFftOut.
             */
            const auto stat = cfr_one_iteration(symbol, reference.data());

            // i == 0 always zero power, so the MER ends up being NaN
            if (i > 0) {
                myPaprAfterCFR.process_block(symbol, mySpacing);
            }

            if (i > 0 and myMERCalcIndex == i) {
                /* MER definition, ETSI ETR 290, Annex C
                 *
                 *                       \sum I^2 + Q^2
                 * MER[dB] = 10 log_10( ---------------- )
                 *                      \sum dI^2 + dQ^2
                 * Where I and Q are the ideal coordinates, and dI and dQ are
                 * the errors in the received datapoints.
                 *
                 * In our case, we consider the constellation points given to the
                 * OfdmGenerator as "ideal", and we compare the CFR output to it.
                 */
                double sum_iq = 0;
                double sum_delta = 0;
                for (size_t j = 0; j < mySpacing; j++) {
                    sum_iq += (double)std::norm(before_cfr[j]);
                    sum_delta += (double)std::norm(symbol[j] - before_cfr[j]);
                }

                // Clamp to 90dB, otherwise the MER average is going to be inf
                const double mer = sum_delta > 0 ?
                    10.0 * std::log10(sum_iq / sum_delta) : 90;
                myMERs.push_back(mer);
            }

            num_clip += stat.clip_count;
            num_error_clip += stat.errclip_count;
        }

        memcpy(out, myFftOut, mySpacing * sizeof(FFTW_TYPE));

        in += myNbCarriers;
        out += mySpacing;
    }

    if (myCfr) {
        std::lock_guard<std::mutex> lock(myCfrRcMutex);

        const double num_samps = myNbSymbols * mySpacing;
        const double clip_ratio = (double)num_clip / num_samps;

        myClipRatios.push_back(clip_ratio);
        while (myClipRatios.size() > MAX_CLIP_STATS) {
            myClipRatios.pop_front();
        }

        const double errclip_ratio = (double)num_error_clip / num_samps;
        myErrorClipRatios.push_back(errclip_ratio);
        while (myErrorClipRatios.size() > MAX_CLIP_STATS) {
            myErrorClipRatios.pop_front();
        }

        while (myMERs.size() > MAX_CLIP_STATS) {
            myMERs.pop_front();
        }
    }

    return sizeOut;
}

OfdmGeneratorCF32::cfr_iter_stat_t OfdmGeneratorCF32::cfr_one_iteration(
        complexf *symbol, const complexf *reference)
{
    // use std::norm instead of std::abs to avoid calculating the
    // square roots
    const float clip_squared = myCfrClip * myCfrClip;

    OfdmGeneratorCF32::cfr_iter_stat_t ret;

    // Clip
    for (size_t i = 0; i < mySpacing; i++) {
        const float mag_squared = std::norm(symbol[i]);
        if (mag_squared > clip_squared) {
            // normalise absolute value to myCfrClip:
            // x_clipped = x * clip / |x|
            //           = x * sqrt(clip_squared) / sqrt(mag_squared)
            //           = x * sqrt(clip_squared / mag_squared)
            symbol[i] *= std::sqrt(clip_squared / mag_squared);
            ret.clip_count++;
        }
    }

    // Take FFT of our clipped signal
    memcpy(myCfrPostClip, symbol, mySpacing * sizeof(FFTW_TYPE));
    fftwf_execute(myCfrFft); // FFT from myCfrPostClip to myCfrPostFft

    // Calculate the error in frequency domain by subtracting our reference
    // and clip it to myCfrErrorClip. By adding this clipped error signal
    // to our FFT output, we compensate the introduced error to some
    // extent.
    const float err_clip_squared = myCfrErrorClip * myCfrErrorClip;

    std::vector<float> error_norm(mySpacing);

    for (size_t i = 0; i < mySpacing; i++) {
        // FFTW computes an unnormalised transform, i.e. a FFT-IFFT pair
        // or vice-versa gives back the original vector scaled by a factor
        // FFT-size. Because we're comparing our constellation point
        // (calculated with IFFT-clip-FFT) against reference (input to
        // the IFFT), we need to divide by our FFT size.
        const complexf constellation_point =
            reinterpret_cast<complexf*>(myCfrPostFft)[i] / (float)mySpacing;

        complexf error = reference[i] - constellation_point;

        const float mag_squared = std::norm(error);
        error_norm[i] = mag_squared;

        if (mag_squared > err_clip_squared) {
            error *= std::sqrt(err_clip_squared / mag_squared);
            ret.errclip_count++;
        }

        // Update the input to the FFT directly to avoid another copy for the
        // subsequence IFFT
        complexf *fft_in = reinterpret_cast<complexf*>(myFftIn);
        fft_in[i] = constellation_point + error;
    }

    // Run our error-compensated symbol through the IFFT again
    fftwf_execute(myFftPlan); // IFFT from myFftIn to myFftOut

    return ret;
}


void OfdmGeneratorCF32::set_parameter(const std::string& parameter,
                                  const std::string& value)
{
    using namespace std;
    stringstream ss(value);
    ss.exceptions ( stringstream::failbit | stringstream::badbit );

    if (parameter == "cfr") {
        ss >> myCfr;
        myPaprClearRequest.store(true);
    }
    else if (parameter == "clip") {
        ss >> myCfrClip;
        myPaprClearRequest.store(true);
    }
    else if (parameter == "errorclip") {
        ss >> myCfrErrorClip;
        myPaprClearRequest.store(true);
    }
    else if (parameter == "clip_stats" or parameter == "papr") {
        throw ParameterError("Parameter '" + parameter + "' is read-only");
    }
    else {
        stringstream ss_err;
        ss_err << "Parameter '" << parameter
            << "' is not exported by controllable " << get_rc_name();
        throw ParameterError(ss_err.str());
    }
}

const std::string OfdmGeneratorCF32::get_parameter(const std::string& parameter) const
{
    using namespace std;
    stringstream ss;
    if (parameter == "cfr") {
        ss << myCfr;
    }
    else if (parameter == "clip") {
        ss << std::fixed << myCfrClip;
    }
    else if (parameter == "errorclip") {
        ss << std::fixed << myCfrErrorClip;
    }
    else if (parameter == "clip_stats") {
        std::lock_guard<std::mutex> lock(myCfrRcMutex);
        if (myClipRatios.empty() or myErrorClipRatios.empty() or myMERs.empty()) {
            ss << "No stats available";
        }
        else {
            const double avg_clip_ratio =
                std::accumulate(myClipRatios.begin(), myClipRatios.end(), 0.0) /
                myClipRatios.size();

            const double avg_errclip_ratio =
                std::accumulate(myErrorClipRatios.begin(), myErrorClipRatios.end(), 0.0) /
                myErrorClipRatios.size();

            const double avg_mer =
                std::accumulate(myMERs.begin(), myMERs.end(), 0.0) /
                myMERs.size();

            ss << "Statistics : " << std::fixed <<
                avg_clip_ratio * 100 << "%"" samples clipped, " <<
                avg_errclip_ratio * 100 << "%"" errors clipped. " <<
                "MER after CFR: " << avg_mer << " dB";
        }
    }
    else if (parameter == "papr") {
        const double papr_before = myPaprBeforeCFR.calculate_papr();
        const double papr_after = myPaprAfterCFR.calculate_papr();

        ss << "PAPR [dB]: " << std::fixed <<
            (papr_before == 0 ? string("N/A") : to_string(papr_before)) <<
            ", " <<
            (papr_after == 0 ? string("N/A") : to_string(papr_after));
    }
    else {
        ss << "Parameter '" << parameter <<
            "' is not exported by controllable " << get_rc_name();
        throw ParameterError(ss.str());
    }
    return ss.str();
}

const json::map_t OfdmGeneratorCF32::get_all_values() const
{
    json::map_t map;
    // TODO needs rework of the values
    return map;
}

OfdmGeneratorFixed::OfdmGeneratorFixed(size_t nbSymbols,
                             size_t nbCarriers,
                             size_t spacing,
                             bool& enableCfr,
                             float& cfrClip,
                             float& cfrErrorClip,
                             bool inverse) :
    ModCodec(),
    myNbSymbols(nbSymbols),
    myNbCarriers(nbCarriers),
    mySpacing(spacing)
{
    PDEBUG("OfdmGenerator::OfdmGenerator(%zu, %zu, %zu, %s) @ %p\n",
            nbSymbols, nbCarriers, spacing, inverse ? "true" : "false", this);

    etiLog.level(info) << "Using KISS FFT by Mark Borgerding for fixed-point transform";

    if (nbCarriers > spacing) {
        throw std::runtime_error("OfdmGenerator nbCarriers > spacing!");
    }

    if (inverse) {
        myPosDst = (nbCarriers & 1 ? 0 : 1);
        myPosSrc = 0;
        myPosSize = (nbCarriers + 1) / 2;
        myNegDst = spacing - (nbCarriers / 2);
        myNegSrc = (nbCarriers + 1) / 2;
        myNegSize = nbCarriers / 2;
    }
    else {
        myPosDst = (nbCarriers & 1 ? 0 : 1);
        myPosSrc = nbCarriers / 2;
        myPosSize = (nbCarriers + 1) / 2;
        myNegDst = spacing - (nbCarriers / 2);
        myNegSrc = 0;
        myNegSize = nbCarriers / 2;
    }
    myZeroDst = myPosDst + myPosSize;
    myZeroSize = myNegDst - myZeroDst;

    PDEBUG("  myPosDst: %u\n", myPosDst);
    PDEBUG("  myPosSrc: %u\n", myPosSrc);
    PDEBUG("  myPosSize: %u\n", myPosSize);
    PDEBUG("  myNegDst: %u\n", myNegDst);
    PDEBUG("  myNegSrc: %u\n", myNegSrc);
    PDEBUG("  myNegSize: %u\n", myNegSize);
    PDEBUG("  myZeroDst: %u\n", myZeroDst);
    PDEBUG("  myZeroSize: %u\n", myZeroSize);

    const int N = mySpacing; // The size of the FFT

    const size_t nbytes = N * sizeof(kiss_fft_cpx);
    myFftIn = (kiss_fft_cpx*)KISS_FFT_MALLOC(nbytes);
    myFftOut = (kiss_fft_cpx*)KISS_FFT_MALLOC(nbytes);
    memset(myFftIn, 0, nbytes);

    myKissCfg = kiss_fft_alloc(N, inverse, nullptr, nullptr);
}

OfdmGeneratorFixed::~OfdmGeneratorFixed()
{
    if (myKissCfg) KISS_FFT_FREE(myKissCfg);
    if (myFftIn) KISS_FFT_FREE(myFftIn);
    if (myFftOut) KISS_FFT_FREE(myFftOut);
}

int OfdmGeneratorFixed::process(Buffer* const dataIn, Buffer* dataOut)
{
    dataOut->setLength(myNbSymbols * mySpacing * sizeof(kiss_fft_cpx));

    kiss_fft_cpx *in = reinterpret_cast<kiss_fft_cpx*>(dataIn->getData());
    kiss_fft_cpx *out = reinterpret_cast<kiss_fft_cpx*>(dataOut->getData());

    size_t sizeIn = dataIn->getLength() / sizeof(kiss_fft_cpx);
    size_t sizeOut = dataOut->getLength() / sizeof(kiss_fft_cpx);

    if (sizeIn != myNbSymbols * myNbCarriers) {
        PDEBUG("Nb symbols: %zu\n", myNbSymbols);
        PDEBUG("Nb carriers: %zu\n", myNbCarriers);
        PDEBUG("Spacing: %zu\n", mySpacing);
        PDEBUG("\n%zu != %zu\n", sizeIn, myNbSymbols * myNbCarriers);
        throw std::runtime_error(
                "OfdmGenerator::process input size not valid!");
    }
    if (sizeOut != myNbSymbols * mySpacing) {
        PDEBUG("Nb symbols: %zu\n", myNbSymbols);
        PDEBUG("Nb carriers: %zu\n", myNbCarriers);
        PDEBUG("Spacing: %zu\n", mySpacing);
        PDEBUG("\n%zu != %zu\n", sizeIn, myNbSymbols * mySpacing);
        throw std::runtime_error(
                "OfdmGenerator::process output size not valid!");
    }

    for (size_t i = 0; i < myNbSymbols; i++) {
        myFftIn[0].r = 0;
        myFftIn[0].i = 0;

        /* For TM I this is:
         * ZeroDst=769 ZeroSize=511
         * PosSrc=0 PosDst=1 PosSize=768
         * NegSrc=768 NegDst=1280 NegSize=768
         */
        memset(&myFftIn[myZeroDst], 0, myZeroSize * sizeof(kiss_fft_cpx));
        memcpy(&myFftIn[myPosDst], &in[myPosSrc], myPosSize * sizeof(kiss_fft_cpx));
        memcpy(&myFftIn[myNegDst], &in[myNegSrc], myNegSize * sizeof(kiss_fft_cpx));

        kiss_fft(myKissCfg, myFftIn, myFftOut);

        memcpy(out, myFftOut, mySpacing * sizeof(kiss_fft_cpx));

        in += myNbCarriers;
        out += mySpacing;
    }

    return sizeOut;
}

#ifdef HAVE_DEXTER
OfdmGeneratorDEXTER::OfdmGeneratorDEXTER(size_t nbSymbols,
                             size_t nbCarriers,
                             size_t spacing,
                             bool& enableCfr,
                             float& cfrClip,
                             float& cfrErrorClip,
                             bool inverse) :
    ModCodec(),
    myNbSymbols(nbSymbols),
    myNbCarriers(nbCarriers),
    mySpacing(spacing)
{
    PDEBUG("OfdmGeneratorDEXTER::OfdmGeneratorDEXTER(%zu, %zu, %zu, %s) @ %p\n",
            nbSymbols, nbCarriers, spacing, inverse ? "true" : "false", this);

    etiLog.level(info) << "Using DEXTER FFT Accelerator for fixed-point transform";

    if (nbCarriers > spacing) {
        throw std::runtime_error("OfdmGenerator nbCarriers > spacing!");
    }

    if (inverse) {
        myPosDst = (nbCarriers & 1 ? 0 : 1);
        myPosSrc = 0;
        myPosSize = (nbCarriers + 1) / 2;
        myNegDst = spacing - (nbCarriers / 2);
        myNegSrc = (nbCarriers + 1) / 2;
        myNegSize = nbCarriers / 2;
    }
    else {
        myPosDst = (nbCarriers & 1 ? 0 : 1);
        myPosSrc = nbCarriers / 2;
        myPosSize = (nbCarriers + 1) / 2;
        myNegDst = spacing - (nbCarriers / 2);
        myNegSrc = 0;
        myNegSize = nbCarriers / 2;
    }
    myZeroDst = myPosDst + myPosSize;
    myZeroSize = myNegDst - myZeroDst;

    PDEBUG("  myPosDst: %u\n", myPosDst);
    PDEBUG("  myPosSrc: %u\n", myPosSrc);
    PDEBUG("  myPosSize: %u\n", myPosSize);
    PDEBUG("  myNegDst: %u\n", myNegDst);
    PDEBUG("  myNegSrc: %u\n", myNegSrc);
    PDEBUG("  myNegSize: %u\n", myNegSize);
    PDEBUG("  myZeroDst: %u\n", myZeroDst);
    PDEBUG("  myZeroSize: %u\n", myZeroSize);

    const size_t nbytes_in = mySpacing * sizeof(complexfix);
    const size_t nbytes_out = mySpacing * 2 * sizeof(int32_t);

#define IIO_ENSURE(expr, err) { \
    if (!(expr)) { \
        etiLog.log(error, "%s (%s:%d)\n", err, __FILE__, __LINE__); \
        throw std::runtime_error("Failed to set FFT for OfdmGeneratorDEXTER"); \
    } \
}
    IIO_ENSURE((m_ctx = iio_create_default_context()), "No context");
    IIO_ENSURE(m_dev_in = iio_context_find_device(m_ctx, "fft-accelerator-in"), "no dev");
    IIO_ENSURE(m_dev_out = iio_context_find_device(m_ctx, "fft-accelerator-out"), "no dev");
    IIO_ENSURE(m_channel_in = iio_device_find_channel(m_dev_in, "voltage0", true), "no channel");
    IIO_ENSURE(m_channel_out = iio_device_find_channel(m_dev_out, "voltage0", false), "no channel");

    iio_channel_enable(m_channel_in);
    iio_channel_enable(m_channel_out);

    m_buf_in = iio_device_create_buffer(m_dev_in, nbytes_in, false);
    if (!m_buf_in) {
        throw std::runtime_error("OfdmGeneratorDEXTER could not create in buffer");
    }

    m_buf_out = iio_device_create_buffer(m_dev_out, nbytes_out, false);
    if (!m_buf_out) {
        throw std::runtime_error("OfdmGeneratorDEXTER could not create out buffer");
    }
}

OfdmGeneratorDEXTER::~OfdmGeneratorDEXTER()
{
    if (m_buf_in) {
        iio_buffer_destroy(m_buf_in);
        m_buf_in = nullptr;
    }

    if (m_buf_out) {
        iio_buffer_destroy(m_buf_out);
        m_buf_out = nullptr;
    }

    if (m_channel_in) {
        iio_channel_disable(m_channel_in);
        m_channel_in = nullptr;
    }

    if (m_channel_out) {
        iio_channel_disable(m_channel_out);
        m_channel_out = nullptr;
    }

    if (m_ctx) {
        iio_context_destroy(m_ctx);
        m_ctx = nullptr;
    }
}

int OfdmGeneratorDEXTER::process(Buffer* const dataIn, Buffer* dataOut)
{
    dataOut->setLength(myNbSymbols * mySpacing * sizeof(complexfix_wide));

    complexfix *in = reinterpret_cast<complexfix*>(dataIn->getData());
    complexfix_wide *out = reinterpret_cast<complexfix_wide*>(dataOut->getData());

    size_t sizeIn = dataIn->getLength() / sizeof(complexfix);
    size_t sizeOut = dataOut->getLength() / sizeof(complexfix_wide);

    if (sizeIn != myNbSymbols * myNbCarriers) {
        PDEBUG("Nb symbols: %zu\n", myNbSymbols);
        PDEBUG("Nb carriers: %zu\n", myNbCarriers);
        PDEBUG("Spacing: %zu\n", mySpacing);
        PDEBUG("\n%zu != %zu\n", sizeIn, myNbSymbols * myNbCarriers);
        throw std::runtime_error(
                "OfdmGenerator::process input size not valid!");
    }
    if (sizeOut != myNbSymbols * mySpacing) {
        PDEBUG("Nb symbols: %zu\n", myNbSymbols);
        PDEBUG("Nb carriers: %zu\n", myNbCarriers);
        PDEBUG("Spacing: %zu\n", mySpacing);
        PDEBUG("\n%zu != %zu\n", sizeIn, myNbSymbols * mySpacing);
        throw std::runtime_error("OfdmGenerator::process output size not valid!");
    }

    ptrdiff_t iio_buf_size = (uint8_t*)iio_buffer_end(m_buf_in) - (uint8_t*)iio_buffer_start(m_buf_in);
    if (iio_buf_size != (ssize_t)(mySpacing * sizeof(complexfix))) {
        throw std::runtime_error("OfdmGenerator::process incorrect iio buffer size!");
    }

    complexfix *fft_in = reinterpret_cast<complexfix*>(iio_buffer_start(m_buf_in));

    fft_in[0] = static_cast<complexfix::value_type>(0);
    for (size_t i = 0; i < myZeroSize; i++) {
        fft_in[myZeroDst + i] = static_cast<complexfix::value_type>(0);
    }

    for (size_t i = 0; i < myNbSymbols; i++) {
        /* For TM I this is:
         * ZeroDst=769 ZeroSize=511
         * PosSrc=0 PosDst=1 PosSize=768
         * NegSrc=768 NegDst=1280 NegSize=768
         */
        memcpy(&fft_in[myPosDst], &in[myPosSrc], myPosSize * sizeof(complexfix));
        memcpy(&fft_in[myNegDst], &in[myNegSrc], myNegSize * sizeof(complexfix));

        ssize_t nbytes_tx = iio_buffer_push(m_buf_in);
        if (nbytes_tx < 0) {
            throw std::runtime_error("OfdmGenerator::process error pushing IIO buffer!");
        }

        ssize_t nbytes_rx = iio_buffer_refill(m_buf_out);
        if (nbytes_rx < 0) {
            throw std::runtime_error("OfdmGenerator::process error refilling IIO buffer!");
        }

        ptrdiff_t p_inc = iio_buffer_step(m_buf_out);
        if (p_inc != 1) {
            throw std::runtime_error("OfdmGenerator::process Wrong p_inc");
        }

        // The FFT Accelerator takes 16-bit I + 16-bit Q, and outputs 32-bit I and 32-bit Q.
        // The formatconvert will take care of this
        const uint8_t *fft_out = (const uint8_t*)iio_buffer_first(m_buf_out, m_channel_out);
        const uint8_t *fft_out_end = (const uint8_t*)iio_buffer_end(m_buf_out);
        constexpr size_t sizeof_out_iq = sizeof(complexfix_wide);
        if ((fft_out_end - fft_out) != (ssize_t)(mySpacing * sizeof_out_iq)) {
            fprintf(stderr, "FFT_OUT: %p %p %zu %zu\n",
                    fft_out, fft_out_end, (fft_out_end - fft_out),
                    mySpacing * sizeof_out_iq);
            throw std::runtime_error("OfdmGenerator::process fft_out length invalid!");
        }

        memcpy(out, fft_out, mySpacing * sizeof_out_iq);

        in += myNbCarriers;
        out += mySpacing;
    }

    return sizeOut;
}

#endif // HAVE_DEXTER