mirror of https://github.com/pvnis/srsRAN_4G.git
CFO correction using LUT
ismagom
11 years ago
parent
f5f1ee186e
commit
adf5260e29
@ -0,0 +1,55 @@
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/**
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*
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* \section COPYRIGHT
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*
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* Copyright 2013-2014 The libLTE Developers. See the
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* COPYRIGHT file at the top-level directory of this distribution.
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*
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* \section LICENSE
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*
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* This file is part of the libLTE library.
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*
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* libLTE is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version.
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*
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* libLTE 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 Lesser General Public License for more details.
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*
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* A copy of the GNU Lesser General Public License can be found in
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* the LICENSE file in the top-level directory of this distribution
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* and at http://www.gnu.org/licenses/.
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*
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*/
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#ifndef _cfo_
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#define _cfo_
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#include <complex.h>
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typedef _Complex float cf_t;
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/** If the frequency is changed more than the tolerance, a new table is generated */
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#define CFO_TOLERANCE 0.00001
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#define CFO_CEXPTAB_SIZE 4096
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typedef struct {
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float last_freq;
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float tol;
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int nsamples;
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cexptab_t tab;
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cf_t *cur_cexp;
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}cfo_t;
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int cfo_init(cfo_t *h, int nsamples);
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void cfo_free(cfo_t *h);
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void cfo_set_tol(cfo_t *h, float tol);
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void cfo_correct(cfo_t *h, cf_t *x, float freq);
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#endif
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@ -0,0 +1,80 @@
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/**
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*
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* \section COPYRIGHT
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*
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* Copyright 2013-2014 The libLTE Developers. See the
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* COPYRIGHT file at the top-level directory of this distribution.
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*
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* \section LICENSE
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*
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* This file is part of the libLTE library.
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*
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* libLTE is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version.
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*
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* libLTE 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 Lesser General Public License for more details.
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*
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* A copy of the GNU Lesser General Public License can be found in
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* the LICENSE file in the top-level directory of this distribution
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* and at http://www.gnu.org/licenses/.
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*
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*/
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#include <strings.h>
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#include <stdlib.h>
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#include <math.h>
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#include "lte/utils/cexptab.h"
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#include "lte/sync/cfo.h"
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#include "lte/utils/vector.h"
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#include "lte/utils/debug.h"
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int cfo_init(cfo_t *h, int nsamples) {
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int ret = -1;
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bzero(h, sizeof(cfo_t));
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if (cexptab_init(&h->tab, CFO_CEXPTAB_SIZE)) {
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goto clean;
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}
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h->cur_cexp = malloc(sizeof(cf_t) * nsamples);
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if (!h->cur_cexp) {
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goto clean;
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}
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h->tol = CFO_TOLERANCE;
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h->last_freq = 0;
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h->nsamples = nsamples;
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cexptab_gen(&h->tab, h->cur_cexp, h->last_freq, h->nsamples);
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ret = 0;
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clean:
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if (ret == -1) {
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cfo_free(h);
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}
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return ret;
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}
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void cfo_free(cfo_t *h) {
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cexptab_free(&h->tab);
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if (h->cur_cexp) {
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free(h->cur_cexp);
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}
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bzero(h, sizeof(cf_t));
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}
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void cfo_set_tol(cfo_t *h, float tol) {
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h->tol = tol;
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}
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void cfo_correct(cfo_t *h, cf_t *x, float freq) {
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if (fabs(h->last_freq - freq) > h->tol) {
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h->last_freq = freq;
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cexptab_gen(&h->tab, h->cur_cexp, h->last_freq, h->nsamples);
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INFO("CFO generating new table for frequency %.4f\n", freq);
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}
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vec_prod_ccc(h->cur_cexp, x, x, h->nsamples);
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}
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@ -0,0 +1,80 @@
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/**
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*
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* \section COPYRIGHT
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*
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* Copyright 2013-2014 The libLTE Developers. See the
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* COPYRIGHT file at the top-level directory of this distribution.
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*
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* \section LICENSE
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*
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* This file is part of the libLTE library.
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*
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* libLTE is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version.
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*
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* libLTE 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 Lesser General Public License for more details.
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*
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* A copy of the GNU Lesser General Public License can be found in
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* the LICENSE file in the top-level directory of this distribution
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* and at http://www.gnu.org/licenses/.
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*
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*/
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#include <stdlib.h>
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#include <math.h>
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#include <string.h>
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#include <assert.h>
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#include <complex.h>
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#include "lte/utils/cexptab.h"
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int cexptab_init(cexptab_t *h, int size) {
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int i;
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h->size = size;
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h->tab = malloc(sizeof(cf_t) * size);
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if (h->tab) {
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for (i = 0; i < size; i++) {
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h->tab[i] = cexpf(_Complex_I * 2 * M_PI * (float) i / size);
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}
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return 0;
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} else {
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return -1;
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}
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}
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void cexptab_free(cexptab_t *h) {
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if (h->tab) {
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free(h->tab);
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}
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bzero(h, sizeof(cexptab_t));
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}
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void cexptab_gen(cexptab_t *h, cf_t *x, float freq, int len) {
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int i;
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unsigned int idx;
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float phase_inc = freq * h->size;
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float phase=0;
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for (i = 0; i < len; i++) {
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idx = (unsigned int) phase;
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x[i] = h->tab[idx];
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phase += phase_inc;
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if (phase >= (float) h->size) {
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phase -= (float) h->size;
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}
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}
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}
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void cexptab_gen_direct(cf_t *x, float freq, int len) {
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int i;
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for (i = 0; i < len; i++) {
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x[i] = cexpf(_Complex_I * 2 * M_PI * freq * i);
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}
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}
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@ -1,131 +0,0 @@
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/**
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*
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* \section COPYRIGHT
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*
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* Copyright 2013-2014 The libLTE Developers. See the
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* COPYRIGHT file at the top-level directory of this distribution.
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*
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* \section LICENSE
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*
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* This file is part of the libLTE library.
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*
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* libLTE is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version.
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*
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* libLTE 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 Lesser General Public License for more details.
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*
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* A copy of the GNU Lesser General Public License can be found in
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* the LICENSE file in the top-level directory of this distribution
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* and at http://www.gnu.org/licenses/.
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*
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*/
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#include <stdlib.h>
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#include <math.h>
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#include <string.h>
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#include <assert.h>
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#include <complex.h>
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#include "lte/utils/nco.h"
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void nco_init(nco_t *nco, int size) {
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int i;
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nco->size=size;
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nco->cost=malloc(size*sizeof(float));
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nco->sint=malloc(size*sizeof(float));
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assert(nco->cost && nco->sint);
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for (i=0;i<size;i++) {
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nco->cost[i] = cosf(2*M_PI*i/size);
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nco->sint[i] = sinf(2*M_PI*i/size);
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}
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}
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void nco_destroy(nco_t *nco) {
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if (nco->cost) {
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free(nco->cost);
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}
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if (nco->sint) {
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free(nco->sint);
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}
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nco->size=0;
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bzero(nco, sizeof(nco_t));
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}
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unsigned int nco_idx(float phase, int size) {
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while(phase>=2*M_PI) {
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phase-=2*M_PI;
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}
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unsigned int idx = (unsigned int) (phase*size/(2*M_PI));
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return idx;
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}
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inline float nco_sin(nco_t *nco, float phase) {
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return nco->sint[nco_idx(phase,nco->size)];
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}
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inline float nco_cos(nco_t *nco, float phase) {
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return nco->cost[nco_idx(phase,nco->size)];
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}
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inline void nco_sincos(nco_t *nco, float phase, float *sin, float *cos) {
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unsigned int idx = nco_idx(phase,nco->size);
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*sin = nco->sint[idx];
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*cos = nco->cost[idx];
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}
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inline _Complex float nco_cexp(nco_t *nco, float arg) {
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float s,c;
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nco_sincos(nco,arg,&s,&c);
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return c+I*s;
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}
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void nco_sin_f(nco_t *nco, float *x, float freq, int len) {
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int i;
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unsigned int idx;
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idx=0;
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for (i=0;i<len;i++) {
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idx=((unsigned int) (freq*i*nco->size/len))%nco->size;
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x[i] = nco->sint[idx];
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}
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}
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void nco_cos_f(nco_t *nco, float *x, float freq, int len) {
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int i;
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unsigned int idx;
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idx=0;
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for (i=0;i<len;i++) {
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idx=((unsigned int) (freq*i*nco->size/len))%nco->size;
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x[i] = nco->cost[idx];
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}
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}
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void nco_cexp_f(nco_t *nco, _Complex float *x, float freq, int len) {
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int i;
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unsigned int idx;
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idx=0;
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for (i=0;i<len;i++) {
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idx=((unsigned int) (freq*i*nco->size/len))%nco->size;
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x[i] = nco->cost[idx] + I*nco->sint[idx];
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}
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}
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void nco_cexp_f_direct(_Complex float *x, float freq, int len) {
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int i;
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for (i=0;i<len;i++) {
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x[i] *= cexpf(_Complex_I * 2 * M_PI * freq * i);
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}
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}
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