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/* -*- c++ -*- */
/*
* Copyright 2013-2014 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 "cc_encoder_impl.h"
#include <math.h>
#include <boost/assign/list_of.hpp>
#include <volk/volk_typedefs.h>
#include <volk/volk.h>
#include <sstream>
#include <stdio.h>
#include <vector>
#include <gnuradio/fec/generic_encoder.h>
#include <gnuradio/fec/cc_common.h>
namespace gr {
namespace fec {
namespace code {
generic_encoder::sptr
cc_encoder::make(int frame_size, int k, int rate,
std::vector<int> polys, int start_state,
cc_mode_t mode, bool padded)
{
return generic_encoder::sptr
(new cc_encoder_impl(frame_size, k, rate,
polys, start_state,
mode, padded));
}
cc_encoder_impl::cc_encoder_impl(int frame_size, int k, int rate,
std::vector<int> polys, int start_state,
cc_mode_t mode, bool padded)
: generic_encoder("cc_encoder"),
d_rate(rate), d_k(k), d_polys(polys),
d_start_state(start_state),
d_mode(mode), d_padding(0)
{
if(static_cast<size_t>(d_rate) != d_polys.size()) {
throw std::runtime_error("cc_encoder: Number of polynomials must be the same as the value of rate");
}
partab_init();
// set up a padding factor. If padding, extends the encoding
// by this many bits to fit into a full byte.
if(padded && (mode == CC_TERMINATED)) {
d_padding = static_cast<int>(8.0f*ceilf(d_rate*(d_k-1)/8.0f) - (d_rate*(d_k-1)));
}
d_max_frame_size = frame_size;
set_frame_size(frame_size);
}
cc_encoder_impl::~cc_encoder_impl()
{
}
int
cc_encoder_impl::get_output_size()
{
return d_output_size;
}
int
cc_encoder_impl::get_input_size()
{
return d_frame_size;
}
bool
cc_encoder_impl::set_frame_size(unsigned int frame_size)
{
bool ret = true;
if(frame_size > d_max_frame_size) {
GR_LOG_INFO(d_logger, boost::format("tried to set frame to %1%; max possible is %2%") \
% frame_size % d_max_frame_size);
frame_size = d_max_frame_size;
ret = false;
}
d_frame_size = frame_size;
if(d_mode == CC_TERMINATED) {
d_output_size = d_rate * (d_frame_size + d_k - 1) + d_padding;
}
/*
else if(d_trunc_intrinsic) {
int cnt = 0;
for(int i = 0; i < d_rate; ++i) {
if (d_polys[i] != 1) {
cnt++;
}
}
d_output_size = (d_rate * (d_frame_size)) + (cnt * (d_k - 1));
}
*/
else {
d_output_size = d_rate * d_frame_size;
}
return ret;
}
double
cc_encoder_impl::rate()
{
return static_cast<double>(d_rate);
}
int
cc_encoder_impl::parity(int x)
{
x ^= (x >> 16);
x ^= (x >> 8);
return parityb(x);
}
int
cc_encoder_impl::parityb(unsigned char x)
{
return Partab[x];
}
void
cc_encoder_impl::partab_init(void)
{
int i,cnt,ti;
/* Initialize parity lookup table */
for(i=0;i<256;i++){
cnt = 0;
ti = i;
while(ti){
if(ti & 1)
cnt++;
ti >>= 1;
}
Partab[i] = cnt & 1;
}
}
void
cc_encoder_impl::generic_work(void *in_buffer, void *out_buffer)
{
const unsigned char *in = (const unsigned char *) in_buffer;
unsigned char *out = (unsigned char *) out_buffer;
unsigned char my_state = d_start_state;
if(d_mode == CC_TAILBITING) {
for(unsigned int i = 0; i < d_k - 1; ++i) {
my_state = (my_state << 1) | (in[d_frame_size - (d_k - 1) + i] & 1);
}
}
for(unsigned int i = 0; i < d_frame_size; ++i) {
my_state = (my_state << 1) | (in[i] & 1);
for(unsigned int j = 0; j < d_rate; ++j) {
out[i * d_rate + j] = parity(my_state & d_polys[j]) == 0 ? 0 : 1;
}
}
if(d_mode == CC_TERMINATED) {
for(unsigned int i = 0; i < d_k - 1; ++i) {
my_state = (my_state << 1) | ((d_start_state >> (d_k - 2 - i)) & 1);
for(unsigned int j = 0; j < d_rate; ++j) {
out[(i + d_frame_size) * d_rate + j] = parity(my_state & d_polys[j]) == 0 ? 0 : 1;
}
}
}
if(d_mode == CC_TRUNCATED) {
my_state = d_start_state;
}
d_start_state = my_state;
}
} /* namespace code */
} /* namespace fec */
} /* namespace gr */
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