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/*
Copyright (C) 2014 CSP Innovazione nelle ICT s.c.a r.l. (http://www.csp.it/)
Copyright (C) 2020 Matthias P. Braendli (http://www.opendigitalradio.org)
Copyright (C) 2015 Data Path
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 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 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/>.
Authors:
Sergio Sagliocco <sergio.sagliocco@csp.it>
Matthias P. Braendli <matthias@mpb.li>
/ | |- ')|) |-|_ _ (|,_ .| _ ,_ \
Data Path \(|(||_(|/_| (||_||(a)_||||(|||.(_()|||/
*/
#include <vector>
#include <sstream>
#include "watermarkdecoder.hpp"
static std::string calc_watermark(const std::vector<bool>& bits)
{
// First try to find the 0x55 0x55 sync in the waternark data
size_t bit_ix;
int alternance_count = 0;
bool last_bit = 1;
for (bit_ix = 0; bit_ix < bits.size(); bit_ix++) {
if (alternance_count == 16) {
break;
}
else {
if (last_bit != bits[bit_ix]) {
last_bit = bits[bit_ix];
alternance_count++;
}
else {
alternance_count = 0;
last_bit = 1;
}
}
}
if (bit_ix < bits.size()) {
fprintf(stderr, "Found SYNC at offset %zu out of %zu\n",
bit_ix - alternance_count, bits.size());
std::stringstream watermark_ss;
uint8_t b = 0;
size_t i = 0;
while (bit_ix < bits.size()) {
b |= bits[bit_ix] << (7 - i);
if (i == 7) {
watermark_ss << (char)b;
b = 0;
i = 0;
}
else {
i++;
}
bit_ix += 2;
}
return watermark_ss.str();
}
else {
return "";
}
}
WatermarkDecoder::WatermarkDecoder() {}
void WatermarkDecoder::push_fig0_1_bit(bool bit)
{
// The order of FIG0_1 subchannels represents the bits
m_fig0_1_bits.push_back(bit);
}
void WatermarkDecoder::push_confind_bit(bool confind)
{
// The ConfInd of FIG 0/10 contains the CRC-DABMUX and ODR-DabMux watermark
m_confind_bits.push_back(confind);
}
std::string WatermarkDecoder::calculate_watermark()
{
std::string w_old = calc_watermark(m_confind_bits);
std::string w_new = calc_watermark(m_fig0_1_bits);
if (not w_new.empty()) {
return w_new;
}
else if (not w_old.empty()) {
return w_old + " (old watermark)";
}
else {
return "(NOT FOUND)";
}
}
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