mirror of
https://github.com/gnss-sdr/gnss-sdr
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168 lines
5.2 KiB
C++
168 lines
5.2 KiB
C++
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/*!
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* \file cpu_multicorrelator.cc
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* \brief High optimized CPU vector multiTAP correlator class
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* \authors <ul>
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* <li> Javier Arribas, 2015. jarribas(at)cttc.es
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* </ul>
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*
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* Class that implements a high optimized vector multiTAP correlator class for CPUs
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*
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* -------------------------------------------------------------------------
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*
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* Copyright (C) 2010-2015 (see AUTHORS file for a list of contributors)
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*
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* GNSS-SDR is a software defined Global Navigation
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* Satellite Systems receiver
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*
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* This file is part of GNSS-SDR.
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*
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* GNSS-SDR is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* GNSS-SDR is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNSS-SDR. If not, see <http://www.gnu.org/licenses/>.
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*
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* -------------------------------------------------------------------------
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*/
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#include "cpu_multicorrelator.h"
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#include <iostream>
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#include <volk/volk.h>
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#include <gnuradio/fxpt.h> // fixed point sine and cosine
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#include <cmath>
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bool cpu_multicorrelator::init(
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int max_signal_length_samples,
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int n_correlators
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)
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{
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// ALLOCATE MEMORY FOR INTERNAL vectors
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size_t size = max_signal_length_samples * sizeof(std::complex<float>);
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// NCO signal
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d_nco_in=static_cast<std::complex<float>*>(volk_malloc(size, volk_get_alignment()));
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// Doppler-free signal
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d_sig_doppler_wiped=static_cast<std::complex<float>*>(volk_malloc(size, volk_get_alignment()));
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d_local_codes_resampled=new std::complex<float>*[n_correlators];
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for (int n=0;n<n_correlators;n++)
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{
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d_local_codes_resampled[n]=static_cast<std::complex<float>*>(volk_malloc(size, volk_get_alignment()));
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}
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d_n_correlators=n_correlators;
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return true;
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}
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bool cpu_multicorrelator::set_local_code_and_taps(
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int code_length_chips,
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const std::complex<float>* local_code_in,
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float *shifts_chips
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)
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{
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d_local_code_in=local_code_in;
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d_shifts_chips=shifts_chips;
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d_code_length_chips=code_length_chips;
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return true;
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}
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bool cpu_multicorrelator::set_input_output_vectors(
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std::complex<float>* corr_out,
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const std::complex<float>* sig_in
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)
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{
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// Save CPU pointers
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d_sig_in =sig_in;
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d_corr_out = corr_out;
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return true;
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}
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void cpu_multicorrelator::update_local_code(int correlator_length_samples,float rem_code_phase_chips, float code_phase_step_chips)
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{
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float local_code_chip_index;
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for (int current_correlator_tap=0; current_correlator_tap<d_n_correlators;current_correlator_tap++)
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{
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for (int n = 0; n < correlator_length_samples; n++)
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{
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// resample code for current tap
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local_code_chip_index= fmod(code_phase_step_chips*static_cast<float>(n)+ d_shifts_chips[current_correlator_tap] - rem_code_phase_chips, d_code_length_chips);
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//Take into account that in multitap correlators, the shifts can be negative!
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if (local_code_chip_index<0.0) local_code_chip_index+=d_code_length_chips;
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d_local_codes_resampled[current_correlator_tap][n]=d_local_code_in[static_cast<int>(round(local_code_chip_index))];
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}
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}
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}
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void cpu_multicorrelator::update_local_carrier(int correlator_length_samples, float rem_carr_phase_rad, float phase_step_rad)
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{
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float sin_f, cos_f;
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int phase_step_rad_i = gr::fxpt::float_to_fixed(phase_step_rad);
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int phase_rad_i = gr::fxpt::float_to_fixed(rem_carr_phase_rad);
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for(int i = 0; i < correlator_length_samples; i++)
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{
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gr::fxpt::sincos(phase_rad_i, &sin_f, &cos_f);
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d_nco_in[i] = std::complex<float>(cos_f, -sin_f);
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phase_rad_i += phase_step_rad_i;
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}
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}
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bool cpu_multicorrelator::Carrier_wipeoff_multicorrelator_resampler(
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float rem_carrier_phase_in_rad,
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float phase_step_rad,
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float rem_code_phase_chips,
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float code_phase_step_chips,
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int signal_length_samples)
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{
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update_local_carrier(signal_length_samples, rem_carrier_phase_in_rad, phase_step_rad);
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update_local_code(signal_length_samples,rem_code_phase_chips, code_phase_step_chips);
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volk_32fc_x2_multiply_32fc(d_sig_doppler_wiped, d_sig_in, d_nco_in, signal_length_samples);
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for (int current_correlator_tap=0; current_correlator_tap<d_n_correlators;current_correlator_tap++)
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{
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volk_32fc_x2_dot_prod_32fc(&d_corr_out[current_correlator_tap], d_sig_doppler_wiped, d_local_codes_resampled[current_correlator_tap], signal_length_samples);
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}
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return true;
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}
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cpu_multicorrelator::cpu_multicorrelator()
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{
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d_sig_in=NULL;
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d_nco_in=NULL;
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d_sig_doppler_wiped=NULL;
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d_local_code_in=NULL;
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d_shifts_chips=NULL;
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d_corr_out=NULL;
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d_code_length_chips=0;
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d_n_correlators=0;
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}
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bool cpu_multicorrelator::free()
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{
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// Free memory
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if (d_sig_doppler_wiped!=NULL) volk_free(d_sig_doppler_wiped);
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if (d_nco_in!=NULL) volk_free(d_nco_in);
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for (int n=0;n<d_n_correlators;n++)
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{
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volk_free(d_local_codes_resampled[n]);
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}
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delete d_local_codes_resampled;
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return true;
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}
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