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149 lines
3.0 KiB
C

/**
*
* \section COPYRIGHT
*
* Copyright 2013-2014 The libLTE Developers. See the
* COPYRIGHT file at the top-level directory of this distribution.
*
* \section LICENSE
*
* This file is part of the libLTE library.
*
* libLTE is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3 of
* the License, or (at your option) any later version.
*
* libLTE 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 Lesser General Public License for more details.
*
* A copy of the GNU Lesser General Public License can be found in
* the LICENSE file in the top-level directory of this distribution
* and at http://www.gnu.org/licenses/.
*
*/
#include <stdio.h>
#include <stdint.h>
#include "liblte/phy/fec/turbocoder.h"
#define NOF_REGS 3
int tcod_init(tcod_t *h, uint32_t max_long_cb) {
if (tc_interl_init(&h->interl, max_long_cb)) {
return -1;
}
h->max_long_cb = max_long_cb;
return 0;
}
void tcod_free(tcod_t *h) {
tc_interl_free(&h->interl);
h->max_long_cb = 0;
}
int tcod_encode(tcod_t *h, char *input, char *output, uint32_t long_cb) {
char reg1_0, reg1_1, reg1_2, reg2_0, reg2_1, reg2_2;
uint32_t i, k = 0, j;
char bit;
char in, out;
uint32_t *per;
if (long_cb > h->max_long_cb) {
fprintf(stderr, "Turbo coder initiated for max_long_cb=%d\n",
h->max_long_cb);
return -1;
}
if (tc_interl_LTE_gen(&h->interl, long_cb)) {
fprintf(stderr, "Error initiating TC interleaver\n");
return -1;
}
per = h->interl.forward;
reg1_0 = 0;
reg1_1 = 0;
reg1_2 = 0;
reg2_0 = 0;
reg2_1 = 0;
reg2_2 = 0;
k = 0;
for (i = 0; i < long_cb; i++) {
bit = input[i];
output[k] = bit;
k++;
in = bit ^ (reg1_2 ^ reg1_1);
out = reg1_2 ^ (reg1_0 ^ in);
reg1_2 = reg1_1;
reg1_1 = reg1_0;
reg1_0 = in;
output[k] = out;
k++;
bit = input[per[i]];
in = bit ^ (reg2_2 ^ reg2_1);
out = reg2_2 ^ (reg2_0 ^ in);
reg2_2 = reg2_1;
reg2_1 = reg2_0;
reg2_0 = in;
output[k] = out;
k++;
}
k = 3 * long_cb;
/* TAILING CODER #1 */
for (j = 0; j < NOF_REGS; j++) {
bit = reg1_2 ^ reg1_1;
output[k] = bit;
k++;
in = bit ^ (reg1_2 ^ reg1_1);
out = reg1_2 ^ (reg1_0 ^ in);
reg1_2 = reg1_1;
reg1_1 = reg1_0;
reg1_0 = in;
output[k] = out;
k++;
}
/* TAILING CODER #2 */
for (j = 0; j < NOF_REGS; j++) {
bit = reg2_2 ^ reg2_1;
output[k] = bit;
k++;
in = bit ^ (reg2_2 ^ reg2_1);
out = reg2_2 ^ (reg2_0 ^ in);
reg2_2 = reg2_1;
reg2_1 = reg2_0;
reg2_0 = in;
output[k] = out;
k++;
}
return 0;
}