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/* -*- c++ -*- */
/*
* Copyright 2015,2016 Free Software Foundation, Inc.
*
* This 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, or (at your option)
* any later version.
*
* This software 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 software; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gnuradio/io_signature.h>
#include "dvbt_energy_dispersal_impl.h"
namespace gr {
namespace dtv {
const int dvbt_energy_dispersal_impl::d_npacks = 8;
const int dvbt_energy_dispersal_impl::d_psize = 188;
const int dvbt_energy_dispersal_impl::d_SYNC = 0x47;
const int dvbt_energy_dispersal_impl::d_NSYNC = 0xB8;
void
dvbt_energy_dispersal_impl::init_prbs()
{
d_reg = 0xa9;
}
int
dvbt_energy_dispersal_impl::clock_prbs(int clocks)
{
int res = 0;
int feedback = 0;
for (int i = 0; i < clocks; i++) {
feedback = ((d_reg >> (14 - 1)) ^ (d_reg >> (15 - 1))) & 0x1;
d_reg = ((d_reg << 1) | feedback) & 0x7fff;
res = (res << 1) | feedback;
}
return res;
}
dvbt_energy_dispersal::sptr
dvbt_energy_dispersal::make(int nblocks)
{
return gnuradio::get_initial_sptr
(new dvbt_energy_dispersal_impl(nblocks));
}
/*
* The private constructor
*/
dvbt_energy_dispersal_impl::dvbt_energy_dispersal_impl(int nblocks)
: gr::block("dvbt_energy_dispersal",
gr::io_signature::make(1, 1, sizeof(unsigned char)),
gr::io_signature::make(1, 1, sizeof(unsigned char) * nblocks * d_npacks * d_psize)),
d_nblocks(nblocks),
d_reg(0xa9)
{
set_relative_rate(1.0/(double) (d_nblocks * d_npacks * d_psize));
}
/*
* Our virtual destructor.
*/
dvbt_energy_dispersal_impl::~dvbt_energy_dispersal_impl()
{
}
void
dvbt_energy_dispersal_impl::forecast (int noutput_items, gr_vector_int &ninput_items_required)
{
// Add one block size for SYNC search
ninput_items_required[0] = d_npacks * (d_psize + 1) * d_nblocks * noutput_items;
}
int
dvbt_energy_dispersal_impl::general_work (int noutput_items,
gr_vector_int &ninput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
const unsigned char *in = (const unsigned char *) input_items[0];
unsigned char *out = (unsigned char *) output_items[0];
int index = 0;
int count = 0;
int ret = 0;
int is_sync = 0;
// Search for SYNC byte
while (is_sync == 0 && index < d_psize) {
if (in[index] == d_SYNC) {
is_sync = 1;
}
else {
index++;
}
}
// If we found a SYNC byte
if (is_sync) {
for (int i = 0; i < (d_nblocks * noutput_items); i++) {
init_prbs();
int sync = d_NSYNC;
for (int j = 0; j < d_npacks; j++) {
if (in[index + count] != d_SYNC) {
GR_LOG_WARN(d_logger, "Malformed MPEG-TS!");
}
out[count++] = sync;
for (int k = 1; k < d_psize; k++) {
out[count] = in[index + count] ^ clock_prbs(d_npacks);
count++;
}
sync = d_SYNC;
clock_prbs(d_npacks);
}
}
consume_each(index + d_npacks * d_psize * d_nblocks * noutput_items);
ret = noutput_items;
}
else {
consume_each(index);
ret = 0;
}
// Tell runtime system how many output items we produced.
return ret;
}
} /* namespace dtv */
} /* namespace gr */
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