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/* -*- c++ -*- */
/*
* Copyright 2017 by Moritz Luca Schmid, Communications Engineering Lab (CEL) / Karlsruhe Institute of Technology (KIT).
*
* 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 "crc16_bb_impl.h"
#include "crc16.h"
namespace gr {
namespace dab {
crc16_bb::sptr
crc16_bb::make(int length = 32, uint16_t generator = 0x1021, uint16_t initial_state = 0xFF)
{
return gnuradio::get_initial_sptr
(new crc16_bb_impl(length, generator, initial_state));
}
crc16_bb_impl::crc16_bb_impl(int length, uint16_t generator, uint16_t initial_state)
: gr::block("crc16_bb",
gr::io_signature::make(1, 1, length * sizeof(char)), /*FIB without CRC (zeros instead)*/
gr::io_signature::make(1, 1, length * sizeof(char))), /*FIB with CRC16*/
d_length(length), d_generator(generator), d_initial_state(initial_state)
{
}
crc16_bb_impl::~crc16_bb_impl()
{
}
void
crc16_bb_impl::forecast(int noutput_items, gr_vector_int &ninput_items_required)
{
ninput_items_required[0] = noutput_items;
}
int
crc16_bb_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 char *in = (const char *) input_items[0];
char *out = (char *) output_items[0];
for (int n = 0; n < noutput_items; n++) {
//push bytes through
for (int i = 0; i < d_length; i++) {
out[i + n * d_length] = in[i + n * d_length];
}
//calculate crc16 word
d_crc = crc16(in + n * d_length, d_length, d_generator, d_initial_state);
//sanity check (last 2 bytes should be zeros)
if (in[30 + n * d_length] != 0 || in[31 + n * d_length] != 0) {
GR_LOG_DEBUG(d_logger, "CRC16 overwrites data (zeros expected)");
}
//write calculated crc to vector (overwrite last 2 bytes)
out[d_length - 2 + n * d_length] = (char) (d_crc >> 8);//add MSByte first to FIB
out[d_length - 1 + n * d_length] =
(char) (out[d_length - 2 + n * d_length] << 8) ^ d_crc; //add LSByte second to FIB
}
// Tell runtime system how many input items we consumed on
// each input stream.
consume_each(noutput_items);
// Tell runtime system how many output items we produced.
return noutput_items;
}
} /* namespace dab */
} /* namespace gr */
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