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141997475c
The m_parms.tot_errs array is not initialized prior to its first use
in the RDSDemod::biphase function. ASAN does not pick up on this
directly, but instead reports it as follows (note that ASAN fills
memory with 0xBE and -1094795586 is 0xBEBEBEBE):
./plugins/channelrx/demodbfm/rdsdemod.cpp:159:95: runtime error: signed
integer overflow: -1094795586 + -1094795586 cannot be represented in type
'int'
The m_parms.subcarr_bb array does not appear to be read prior to
initialization, but we initialize it to zero anyway for the sake
of good hygiene.
213 lines
6.1 KiB
C++
213 lines
6.1 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2015 F4EXB //
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// written by Edouard Griffiths //
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// //
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// This program is free software; you can redistribute it and/or modify //
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// it under the terms of the GNU General Public License as published by //
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// the Free Software Foundation as version 3 of the License, or //
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// //
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// This program is distributed in the hope that it will be useful, //
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// but WITHOUT ANY WARRANTY; without even the implied warranty of //
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
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// GNU General Public License V3 for more details. //
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// //
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// You should have received a copy of the GNU General Public License //
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// along with this program. If not, see <http://www.gnu.org/licenses/>. //
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///////////////////////////////////////////////////////////////////////////////////
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#include "../../channelrx/demodbfm/rdsdemod.h"
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#include <QDebug>
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#undef M_PI
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#define M_PI 3.14159265358979323846
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#undef M_PI_2
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#define M_PI_2 1.57079632679489661923
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const Real RDSDemod::m_pllBeta = 50;
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const Real RDSDemod::m_fsc = 1187.5;
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RDSDemod::RDSDemod()
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// : m_udpDebug(this, 1472, 9995) // UDP debug
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{
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m_srate = 250000;
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m_parms.subcarr_phi = 0;
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memset(m_parms.subcarr_bb, 0, sizeof(m_parms.subcarr_bb));
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m_parms.clock_offset = 0;
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m_parms.clock_phi = 0;
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m_parms.prev_clock_phi = 0;
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m_parms.lo_clock = 0;
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m_parms.prev_lo_clock = 0;
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m_parms.prev_bb = 0;
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m_parms.d_cphi = 0;
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m_parms.acc = 0;
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m_parms.numsamples = 0;
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m_parms.prev_acc = 0;
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m_parms.counter = 0;
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m_parms.reading_frame = 0;
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memset(m_parms.tot_errs, 0, sizeof(m_parms.tot_errs));
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m_parms.dbit = 0;
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m_prev = 0.0f;
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memset(m_xv, 0, 6*sizeof(Real));
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memset(m_yv, 0, 6*sizeof(Real));
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memset(m_xw, 0, 2*sizeof(Real));
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memset(m_yw, 0, 2*sizeof(Real));
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m_report.acc = 0.0f;
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m_report.fclk = 0.0f;
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m_report.qua = 0.0f;
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}
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RDSDemod::~RDSDemod()
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{
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//delete m_socket;
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}
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void RDSDemod::setSampleRate(int srate __attribute__((unused))) /// FIXME: fix rate for now
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{
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}
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bool RDSDemod::process(Real demod, bool& bit)
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{
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bool ret = false;
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//m_udpDebug.write(m_parms.lo_clock * m_parms.subcarr_bb[0]); // UDP debug
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// Subcarrier downmix & phase recovery
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m_parms.subcarr_bb[0] = filter_lp_2400_iq(demod, 0);
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// 1187.5 Hz clock
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/*
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if (m_parms.subcarr_phi > 1e9) // ~ every 37 hours => not really useful
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{
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qDebug("RDSDemod::process: reset 1187.5 Hz clock");
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m_parms.subcarr_phi = 0;
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m_parms.clock_offset = 0;
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}*/
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m_parms.subcarr_phi += (2 * M_PI * m_fsc) / (Real) m_srate;
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m_parms.clock_phi = m_parms.subcarr_phi + m_parms.clock_offset;
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// Clock phase recovery
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if (sign(m_parms.prev_bb) != sign(m_parms.subcarr_bb[0]))
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{
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m_parms.d_cphi = std::fmod(m_parms.clock_phi, M_PI);
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if (m_parms.d_cphi >= M_PI_2)
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{
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m_parms.d_cphi -= M_PI;
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}
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m_parms.clock_offset -= 0.005 * m_parms.d_cphi;
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}
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m_parms.clock_phi = std::fmod(m_parms.clock_phi, 2 * M_PI);
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m_parms.lo_clock = (m_parms.clock_phi < M_PI ? 1 : -1);
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/* Decimate band-limited signal */
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if (m_parms.numsamples % 8 == 0)
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{
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/* biphase symbol integrate & dump */
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m_parms.acc += m_parms.subcarr_bb[0] * m_parms.lo_clock;
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if (sign(m_parms.lo_clock) != sign(m_parms.prev_lo_clock))
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{
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ret = biphase(m_parms.acc, bit, m_parms.clock_phi - m_parms.prev_clock_phi);
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m_parms.acc = 0;
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}
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m_parms.prev_lo_clock = m_parms.lo_clock;
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}
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m_parms.numsamples++;
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m_parms.prev_bb = m_parms.subcarr_bb[0];
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m_parms.prev_clock_phi = m_parms.clock_phi;
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m_prev = demod;
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return ret;
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}
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bool RDSDemod::biphase(Real acc, bool& bit, Real d_cphi)
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{
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bool ret = false;
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if (sign(acc) != sign(m_parms.prev_acc)) // two successive of different sign: error detected
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{
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m_parms.tot_errs[m_parms.counter % 2]++;
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}
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if (m_parms.counter % 2 == m_parms.reading_frame) // two successive of the same sing: OK
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{
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// new bit found
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int b = sign(m_parms.acc + m_parms.prev_acc);
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bit = b ^ m_parms.dbit;
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m_parms.dbit = b;
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ret = true;
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}
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if (m_parms.counter == 0)
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{
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if (m_parms.tot_errs[1 - m_parms.reading_frame] < m_parms.tot_errs[m_parms.reading_frame])
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{
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m_parms.reading_frame = 1 - m_parms.reading_frame;
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}
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m_report.qua = (1.0 * abs(m_parms.tot_errs[0] - m_parms.tot_errs[1]) / (m_parms.tot_errs[0] + m_parms.tot_errs[1])) * 100;
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m_report.acc = acc;
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m_report.fclk = (d_cphi / (2 * M_PI)) * m_srate;
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/*
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qDebug("RDSDemod::biphase: frame: %d acc: %+6.3f errs: %3d %3d qual: %3.0f%% clk: %7.2f",
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m_parms.reading_frame,
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acc,
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m_parms.tot_errs[0],
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m_parms.tot_errs[1],
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m_report.qua,
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m_report.fclk);*/
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m_parms.tot_errs[0] = 0;
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m_parms.tot_errs[1] = 0;
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}
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m_parms.prev_acc = acc; // memorize (z^-1)
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m_parms.counter = (m_parms.counter + 1) % 800;
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return ret;
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}
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Real RDSDemod::filter_lp_2400_iq(Real input, int iqIndex)
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{
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/* Digital filter designed by mkfilter/mkshape/gencode A.J. Fisher
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Command line: /www/usr/fisher/helpers/mkfilter -Bu -Lp -o 10
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-a 4.8000000000e-03 0.0000000000e+00 -l */
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m_xv[iqIndex][0] = m_xv[iqIndex][1]; m_xv[iqIndex][1] = m_xv[iqIndex][2];
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m_xv[iqIndex][2] = input / 4.491730007e+03;
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m_yv[iqIndex][0] = m_yv[iqIndex][1]; m_yv[iqIndex][1] = m_yv[iqIndex][2];
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m_yv[iqIndex][2] = (m_xv[iqIndex][0] + m_xv[iqIndex][2]) + 2 * m_xv[iqIndex][1]
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+ ( -0.9582451124 * m_yv[iqIndex][0]) + ( 1.9573545869 * m_yv[iqIndex][1]);
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return m_yv[iqIndex][2];
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}
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Real RDSDemod::filter_lp_pll(Real input)
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{
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m_xw[0] = m_xw[1];
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m_xw[1] = input / 3.716236217e+01;
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m_yw[0] = m_yw[1];
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m_yw[1] = (m_xw[0] + m_xw[1])
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+ ( 0.9461821078 * m_yw[0]);
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return m_yw[1];
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}
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int RDSDemod::sign(Real a)
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{
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return (a >= 0 ? 1 : 0);
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}
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