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108 lines
2.4 KiB
C
108 lines
2.4 KiB
C
/**
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*
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* \section COPYRIGHT
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*
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* Copyright 2013-2015 The srsLTE 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 srsLTE library.
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*
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* srsLTE is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero 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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* srsLTE 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 Affero General Public License for more details.
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*
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* A copy of the GNU Affero 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 <stdio.h>
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#include <strings.h>
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#include <assert.h>
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#include "srslte/common/sequence.h"
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#define Nc 1600
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/*
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* Pseudo Random Sequence generation.
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* It follows the 3GPP Release 8 (LTE) 36.211
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* Section 7.2
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*/
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void srslte_sequence_set_LTE_pr(srslte_sequence_t *q, uint32_t seed) {
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int n;
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uint32_t *x1, *x2;
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x1 = calloc(Nc + q->len + 31, sizeof(uint32_t));
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if (!x1) {
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perror("calloc");
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return;
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}
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x2 = calloc(Nc + q->len + 31, sizeof(uint32_t));
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if (!x2) {
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free(x1);
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perror("calloc");
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return;
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}
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for (n = 0; n < 31; n++) {
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x2[n] = (seed >> n) & 0x1;
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}
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x1[0] = 1;
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for (n = 0; n < Nc + q->len; n++) {
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x1[n + 31] = (x1[n + 3] + x1[n]) & 0x1;
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x2[n + 31] = (x2[n + 3] + x2[n + 2] + +x2[n+1] + x2[n]) & 0x1;
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}
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for (n = 0; n < q->len; n++) {
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q->c[n] = (x1[n + Nc] + x2[n + Nc]) & 0x1;
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}
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free(x1);
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free(x2);
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}
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int srslte_sequence_LTE_pr(srslte_sequence_t *q, uint32_t len, uint32_t seed) {
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if (srslte_sequence_init(q, len)) {
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return SRSLTE_ERROR;
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}
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q->len = len;
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srslte_sequence_set_LTE_pr(q, seed);
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return SRSLTE_SUCCESS;
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}
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int srslte_sequence_init(srslte_sequence_t *q, uint32_t len) {
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if (q->c && (q->len != len)) {
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free(q->c);
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}
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if (!q->c) {
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q->c = malloc(len * sizeof(uint8_t));
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if (!q->c) {
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return SRSLTE_ERROR;
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}
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q->len = len;
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}
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return SRSLTE_SUCCESS;
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}
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void srslte_sequence_free(srslte_sequence_t *q) {
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if (q->c) {
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free(q->c);
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}
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bzero(q, sizeof(srslte_sequence_t));
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}
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