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/* -*- c++ -*- */
/*
* Copyright 2012 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio 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.
*
* GNU Radio 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 GNU Radio; 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 "decode_ccsds_27_fb_impl.h"
#include <gnuradio/io_signature.h>
namespace gr {
namespace fec {
decode_ccsds_27_fb::sptr decode_ccsds_27_fb::make()
{
return gnuradio::get_initial_sptr(new decode_ccsds_27_fb_impl());
}
decode_ccsds_27_fb_impl::decode_ccsds_27_fb_impl()
: sync_decimator("decode_ccsds_27_fb",
io_signature::make (1, 1, sizeof(float)),
io_signature::make (1, 1, sizeof(char)),
2*8), d_count(0) // Rate 1/2 code, unpacked to packed conversion
{
float RATE = 0.5;
float ebn0 = 12.0;
float esn0 = RATE*pow(10.0, ebn0/10.0);
gen_met(d_mettab, 100, esn0, 0.0, 256);
viterbi_chunks_init(d_state0);
viterbi_chunks_init(d_state1);
}
int
decode_ccsds_27_fb_impl::work(int noutput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
const float *in = (const float*)input_items[0];
unsigned char *out = (unsigned char*)output_items[0];
for (int i = 0; i < noutput_items*16; i++) {
// Translate and clip [-1.0..1.0] to [28..228]
float sample = in[i]*100.0+128.0;
if(sample > 255.0)
sample = 255.0;
else if(sample < 0.0)
sample = 0.0;
unsigned char sym = (unsigned char)(floor(sample));
d_viterbi_in[d_count % 4] = sym;
if((d_count % 4) == 3) {
// Every fourth symbol, perform butterfly operation
viterbi_butterfly2(d_viterbi_in, d_mettab, d_state0, d_state1);
// Every sixteenth symbol, read out a byte
if (d_count % 16 == 11) {
// long metric =
viterbi_get_output(d_state0, out++);
// printf("%li\n", *(out-1), metric);
}
}
d_count++;
}
return noutput_items;
}
} /* namespace fec */
}/* namespace gr */
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