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85 lines
2.0 KiB
C
85 lines
2.0 KiB
C
/**
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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 "liblte/phy/utils/cexptab.h"
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int cexptab_init(cexptab_t *h, uint32_t size) {
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uint32_t 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 LIBLTE_SUCCESS;
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} else {
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return LIBLTE_ERROR;
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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, uint32_t len) {
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uint32_t i;
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uint32_t 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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while (phase >= (float) h->size) {
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phase -= (float) h->size;
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}
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while (phase < 0) {
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phase += (float) h->size;
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}
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idx = (uint32_t) phase;
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x[i] = h->tab[idx];
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phase += phase_inc;
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}
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}
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void cexptab_gen_direct(cf_t *x, float freq, uint32_t len) {
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uint32_t 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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