sdrangel/plugins/channelrx/demoddatv/leansdr/sdr.cpp

///////////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2019, 2021 Edouard Griffiths, F4EXB <f4exb06@gmail.com>             //
//                                                                                   //
// 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 as version 3 of the License, 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 V3 for more details.                                   //
//                                                                                   //
// You should have received a copy of the GNU General Public License                 //
// along with this program. If not, see <http://www.gnu.org/licenses/>.              //
///////////////////////////////////////////////////////////////////////////////////////
#include "sdr.h"

namespace leansdr
{

const char *cstln_base::names[] =
    {
        "BPSK",
        "QPSK",
        "8PSK",
        "16APSK",
        "32APSK",
        "64APSKe",
        "16QAM",
        "64QAM",
        "256QAM"
    };


void softsymb_harden(llr_ss *ss)
{
    for (int b = 0; b < 8; ++b) {
        ss->bits[b] = (ss->bits[b] < 0) ? -127 : 127;
    }
}

void softsymb_harden(hard_ss *ss)
{
    (void)ss; // NOP
}

void softsymb_harden(eucl_ss *ss)
{
    for (int s = 0; s < ss->MAX_SYMBOLS; ++s) {
        ss->dists2[s] = (s == ss->nearest) ? 0 : 1;
    }
}


uint8_t softsymb_to_dump(const llr_ss &ss, int bit)
{
    return 128 - ss.bits[bit];
}

uint8_t softsymb_to_dump(const hard_ss &ss, int bit)
{
    return ((ss >> bit) & 1) ? 255 : 0;
}

uint8_t softsymb_to_dump(const eucl_ss &ss, int bit)
{
    (void)bit;
    return ss.dists2[ss.nearest] >> 8;
}


void to_softsymb(const full_ss *fss, hard_ss *ss)
{
    *ss = fss->nearest;
}

void to_softsymb(const full_ss *fss, eucl_ss *ss)
{
    for (int s = 0; s < ss->MAX_SYMBOLS; ++s) {
        ss->dists2[s] = fss->dists2[s];
    }

    uint16_t best = 65535, best2 = 65535;

    for (int s = 0; s < ss->MAX_SYMBOLS; ++s)
    {
        if (fss->dists2[s] < best)
        {
            best2 = best;
            best = fss->dists2[s];
        }
        else if (fss->dists2[s] < best2)
        {
            best2 = fss->dists2[s];
        }
    }

    ss->discr2 = best2 - best;
    ss->nearest = fss->nearest;
}

void to_softsymb(const full_ss *fss, llr_ss *ss)
{
    for (int b = 0; b < 8; ++b)
    {
        float v = (1.0f - fss->p[b]) / (fss->p[b] + 1e-6);
        int r = logf(v) * 5; // TBD Optimal scaling vs saturation ?

        if (r < -127) {
            r = -127;
        }

        if (r > 127) {
            r = 127;
        }

        ss->bits[b] = r;
    }
}

} // leansdr