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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 <gnuradio/expj.h>
#include <gnuradio/io_signature.h>
#include "ofdm_frame_equalizer_vcvc_impl.h"
#define M_TWOPI (2*M_PI)
static const pmt::pmt_t CARR_OFFSET_KEY = pmt::mp("ofdm_sync_carr_offset");
static const pmt::pmt_t CHAN_TAPS_KEY = pmt::mp("ofdm_sync_chan_taps");
namespace gr {
namespace digital {
ofdm_frame_equalizer_vcvc::sptr
ofdm_frame_equalizer_vcvc::make(
ofdm_equalizer_base::sptr equalizer,
int cp_len,
const std::string &tsb_key,
bool propagate_channel_state,
int fixed_frame_len
)
{
return gnuradio::get_initial_sptr (
new ofdm_frame_equalizer_vcvc_impl(
equalizer, cp_len, tsb_key, propagate_channel_state, fixed_frame_len
)
);
}
ofdm_frame_equalizer_vcvc_impl::ofdm_frame_equalizer_vcvc_impl(
ofdm_equalizer_base::sptr equalizer,
int cp_len,
const std::string &tsb_key,
bool propagate_channel_state,
int fixed_frame_len
) : tagged_stream_block("ofdm_frame_equalizer_vcvc",
io_signature::make(1, 1, sizeof (gr_complex) * equalizer->fft_len()),
io_signature::make(1, 1, sizeof (gr_complex) * equalizer->fft_len()),
tsb_key),
d_fft_len(equalizer->fft_len()),
d_cp_len(cp_len),
d_eq(equalizer),
d_propagate_channel_state(propagate_channel_state),
d_fixed_frame_len(fixed_frame_len),
d_channel_state(equalizer->fft_len(), gr_complex(1, 0))
{
if (tsb_key.empty() && fixed_frame_len == 0) {
throw std::invalid_argument("Either specify a TSB tag or a fixed frame length!");
}
if (d_fixed_frame_len < 0) {
throw std::invalid_argument("Invalid frame length!");
}
if (d_fixed_frame_len) {
set_output_multiple(d_fixed_frame_len);
}
set_relative_rate(1.0);
// Really, we have TPP_ONE_TO_ONE, but the channel state is not propagated
set_tag_propagation_policy(TPP_DONT);
}
ofdm_frame_equalizer_vcvc_impl::~ofdm_frame_equalizer_vcvc_impl()
{
}
void
ofdm_frame_equalizer_vcvc_impl::parse_length_tags(
const std::vector<std::vector<tag_t> > &tags,
gr_vector_int &n_input_items_reqd
) {
if (d_fixed_frame_len) {
n_input_items_reqd[0] = d_fixed_frame_len;
} else {
for (unsigned k = 0; k < tags[0].size(); k++) {
if (tags[0][k].key == pmt::string_to_symbol(d_length_tag_key_str)) {
n_input_items_reqd[0] = pmt::to_long(tags[0][k].value);
}
}
}
}
int
ofdm_frame_equalizer_vcvc_impl::work(int noutput_items,
gr_vector_int &ninput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
{
const gr_complex *in = (const gr_complex *) input_items[0];
gr_complex *out = (gr_complex *) output_items[0];
int carrier_offset = 0;
int frame_len = 0;
if (d_fixed_frame_len) {
frame_len = d_fixed_frame_len;
} else {
frame_len = ninput_items[0];
}
std::vector<tag_t> tags;
get_tags_in_window(tags, 0, 0, 1);
for (unsigned i = 0; i < tags.size(); i++) {
if (pmt::symbol_to_string(tags[i].key) == "ofdm_sync_chan_taps") {
d_channel_state = pmt::c32vector_elements(tags[i].value);
}
if (pmt::symbol_to_string(tags[i].key) == "ofdm_sync_carr_offset") {
carrier_offset = pmt::to_long(tags[i].value);
}
}
// Copy the frame and the channel state vector such that the symbols are shifted to the correct position
if (carrier_offset < 0) {
memset((void *) out, 0x00, sizeof(gr_complex) * (-carrier_offset));
memcpy(
(void *) &out[-carrier_offset], (void *) in,
sizeof(gr_complex) * (d_fft_len * frame_len + carrier_offset)
);
} else {
memset((void *) (out + d_fft_len * frame_len - carrier_offset), 0x00, sizeof(gr_complex) * carrier_offset);
memcpy(
(void *) out, (void *) (in+carrier_offset),
sizeof(gr_complex) * (d_fft_len * frame_len - carrier_offset)
);
}
// Correct the frequency shift on the symbols
gr_complex phase_correction;
for (int i = 0; i < frame_len; i++) {
phase_correction = gr_expj(-M_TWOPI * carrier_offset * d_cp_len / d_fft_len * (i+1));
for (int k = 0; k < d_fft_len; k++) {
out[i*d_fft_len+k] *= phase_correction;
}
}
// Do the equalizing
d_eq->reset();
d_eq->equalize(out, frame_len, d_channel_state);
d_eq->get_channel_state(d_channel_state);
// Update the channel state regarding the frequency offset
phase_correction = gr_expj(M_TWOPI * carrier_offset * d_cp_len / d_fft_len * frame_len);
for (int k = 0; k < d_fft_len; k++) {
d_channel_state[k] *= phase_correction;
}
// Propagate tags (except for the channel state and the TSB tag)
get_tags_in_window(tags, 0, 0, frame_len);
for (size_t i = 0; i < tags.size(); i++) {
if (tags[i].key != CHAN_TAPS_KEY
and tags[i].key != pmt::mp(d_length_tag_key_str)) {
add_item_tag(0, tags[i]);
}
}
// Housekeeping
if (d_propagate_channel_state) {
add_item_tag(0, nitems_written(0),
pmt::string_to_symbol("ofdm_sync_chan_taps"),
pmt::init_c32vector(d_fft_len, d_channel_state));
}
if (d_fixed_frame_len && d_length_tag_key_str.empty()) {
consume_each(frame_len);
}
return frame_len;
}
} /* namespace digital */
} /* namespace gr */
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