PentHertz
/
srsLTE
mirror of https://github.com/PentHertz/srsLTE.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
srsLTE/srslte/lib/fec/turbodecoder_gen.c

397 lines
10 KiB
C
Raw Blame History

/**
*
* \section COPYRIGHT
*
* Copyright 2013-2015 Software Radio Systems Limited
*
* \section LICENSE
*
* This file is part of the srsLTE library.
*
* srsLTE is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of
* the License, or (at your option) any later version.
*
* srsLTE 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 Affero General Public License for more details.
*
* A copy of the GNU Affero 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 <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <strings.h>
#include <math.h>
#include "srslte/fec/turbodecoder_gen.h"
#include "srslte/utils/vector.h"
#define NUMSTATES 8
#define NINPUTS 2
#define TAIL 3
#define TOTALTAIL 12
#define INF 9e4
#define ZERO 9e-4
/************************************************
*
* MAP_GEN is the MAX-LOG-MAP generic implementation of the
* Decoder
*
************************************************/
static void map_gen_beta(srslte_map_gen_vl_t * s, float * input, float * parity,
uint32_t long_cb)
{
float m_b[8], new[8], old[8];
float x, y, xy;
int k;
uint32_t end = long_cb + SRSLTE_TCOD_RATE;
float *beta = s->beta;
uint32_t i;
for (i = 0; i < 8; i++) {
old[i] = beta[8 * (end) + i];
}
for (k = end - 1; k >= 0; k--) {
x = input[k];
y = parity[k];
xy = x + y;
m_b[0] = old[4] + xy;
m_b[1] = old[4];
m_b[2] = old[5] + y;
m_b[3] = old[5] + x;
m_b[4] = old[6] + x;
m_b[5] = old[6] + y;
m_b[6] = old[7];
m_b[7] = old[7] + xy;
new[0] = old[0];
new[1] = old[0] + xy;
new[2] = old[1] + x;
new[3] = old[1] + y;
new[4] = old[2] + y;
new[5] = old[2] + x;
new[6] = old[3] + xy;
new[7] = old[3];
for (i = 0; i < 8; i++) {
if (m_b[i] > new[i])
new[i] = m_b[i];
old[i] = new[i];
beta[8 * k + i] = old[i];
}
}
}
static void map_gen_alpha(srslte_map_gen_vl_t * s, float * input, float * parity, float * output,
uint32_t long_cb)
{
float m_b[8], new[8], old[8], max1[8], max0[8];
float m1, m0;
float x, y, xy;
float out;
uint32_t k;
uint32_t end = long_cb;
float *beta = s->beta;
uint32_t i;
old[0] = 0;
for (i = 1; i < 8; i++) {
old[i] = -INF;
}
for (k = 1; k < end + 1; k++) {
x = input[k - 1];
y = parity[k - 1];
xy = x + y;
m_b[0] = old[0];
m_b[1] = old[3] + y;
m_b[2] = old[4] + y;
m_b[3] = old[7];
m_b[4] = old[1];
m_b[5] = old[2] + y;
m_b[6] = old[5] + y;
m_b[7] = old[6];
new[0] = old[1] + xy;
new[1] = old[2] + x;
new[2] = old[5] + x;
new[3] = old[6] + xy;
new[4] = old[0] + xy;
new[5] = old[3] + x;
new[6] = old[4] + x;
new[7] = old[7] + xy;
for (i = 0; i < 8; i++) {
max0[i] = m_b[i] + beta[8 * k + i];
max1[i] = new[i] + beta[8 * k + i];
}
m1 = max1[0];
m0 = max0[0];
for (i = 1; i < 8; i++) {
if (max1[i] > m1)
m1 = max1[i];
if (max0[i] > m0)
m0 = max0[i];
}
for (i = 0; i < 8; i++) {
if (m_b[i] > new[i])
new[i] = m_b[i];
old[i] = new[i];
}
out = m1 - m0;
output[k - 1] = out;
}
}
static int map_gen_init(srslte_map_gen_vl_t * h, int max_long_cb)
{
bzero(h, sizeof(srslte_map_gen_vl_t));
h->beta = srslte_vec_malloc(sizeof(float) * (max_long_cb + SRSLTE_TCOD_TOTALTAIL + 1) * NUMSTATES);
if (!h->beta) {
perror("srslte_vec_malloc");
return -1;
}
h->max_long_cb = max_long_cb;
return 0;
}
static void map_gen_free(srslte_map_gen_vl_t * h)
{
if (h->beta) {
free(h->beta);
}
bzero(h, sizeof(srslte_map_gen_vl_t));
}
static void map_gen_dec(srslte_map_gen_vl_t * h, float * input, float * parity, float * output,
uint32_t long_cb)
{
uint32_t k;
h->beta[(long_cb + TAIL) * NUMSTATES] = 0;
for (k = 1; k < NUMSTATES; k++)
h->beta[(long_cb + TAIL) * NUMSTATES + k] = -INF;
map_gen_beta(h, input, parity, long_cb);
map_gen_alpha(h, input, parity, output, long_cb);
}
/************************************************
*
* TURBO DECODER INTERFACE
*
************************************************/
int srslte_tdec_gen_init(srslte_tdec_gen_t * h, uint32_t max_long_cb)
{
int ret = -1;
bzero(h, sizeof(srslte_tdec_gen_t));
uint32_t len = max_long_cb + SRSLTE_TCOD_TOTALTAIL;
h->max_long_cb = max_long_cb;
h->llr1 = srslte_vec_malloc(sizeof(float) * len);
if (!h->llr1) {
perror("srslte_vec_malloc");
goto clean_and_exit;
}
h->llr2 = srslte_vec_malloc(sizeof(float) * len);
if (!h->llr2) {
perror("srslte_vec_malloc");
goto clean_and_exit;
}
h->w = srslte_vec_malloc(sizeof(float) * len);
if (!h->w) {
perror("srslte_vec_malloc");
goto clean_and_exit;
}
h->syst = srslte_vec_malloc(sizeof(float) * len);
if (!h->syst) {
perror("srslte_vec_malloc");
goto clean_and_exit;
}
h->parity = srslte_vec_malloc(sizeof(float) * len);
if (!h->parity) {
perror("srslte_vec_malloc");
goto clean_and_exit;
}
if (map_gen_init(&h->dec, h->max_long_cb)) {
goto clean_and_exit;
}
for (int i=0;i<SRSLTE_NOF_TC_CB_SIZES;i++) {
if (srslte_tc_interl_init(&h->interleaver[i], srslte_cbsegm_cbsize(i)) < 0) {
goto clean_and_exit;
}
srslte_tc_interl_LTE_gen(&h->interleaver[i], srslte_cbsegm_cbsize(i));
}
h->current_cbidx = -1;
ret = 0;
clean_and_exit:if (ret == -1) {
srslte_tdec_gen_free(h);
}
return ret;
}
void srslte_tdec_gen_free(srslte_tdec_gen_t * h)
{
if (h->llr1) {
free(h->llr1);
}
if (h->llr2) {
free(h->llr2);
}
if (h->w) {
free(h->w);
}
if (h->syst) {
free(h->syst);
}
if (h->parity) {
free(h->parity);
}
map_gen_free(&h->dec);
for (int i=0;i<SRSLTE_NOF_TC_CB_SIZES;i++) {
srslte_tc_interl_free(&h->interleaver[i]);
}
bzero(h, sizeof(srslte_tdec_gen_t));
}
void srslte_tdec_gen_iteration(srslte_tdec_gen_t * h, float * input, uint32_t long_cb)
{
uint32_t i;
if (h->current_cbidx >= 0) {
uint16_t *inter = h->interleaver[h->current_cbidx].forward;
uint16_t *deinter = h->interleaver[h->current_cbidx].reverse;
// Prepare systematic and parity bits for MAP DEC #1
for (i = 0; i < long_cb; i++) {
h->syst[i] = input[SRSLTE_TCOD_RATE * i] + h->w[i];
h->parity[i] = input[SRSLTE_TCOD_RATE * i + 1];
}
for (i = long_cb; i < long_cb + SRSLTE_TCOD_RATE; i++) {
h->syst[i] = input[SRSLTE_TCOD_RATE * long_cb + NINPUTS * (i - long_cb)];
h->parity[i] = input[SRSLTE_TCOD_RATE * long_cb + NINPUTS * (i - long_cb) + 1];
}
// Run MAP DEC #1
map_gen_dec(&h->dec, h->syst, h->parity, h->llr1, long_cb);
// Prepare systematic and parity bits for MAP DEC #1
for (i = 0; i < long_cb; i++) {
h->syst[i] = h->llr1[inter[i]]
- h->w[inter[i]];
h->parity[i] = input[SRSLTE_TCOD_RATE * i + 2];
}
for (i = long_cb; i < long_cb + SRSLTE_TCOD_RATE; i++) {
h->syst[i] =
input[SRSLTE_TCOD_RATE * long_cb + NINPUTS * SRSLTE_TCOD_RATE + NINPUTS * (i - long_cb)];
h->parity[i] = input[SRSLTE_TCOD_RATE * long_cb + NINPUTS * SRSLTE_TCOD_RATE
+ NINPUTS * (i - long_cb) + 1];
}
// Run MAP DEC #2
map_gen_dec(&h->dec, h->syst, h->parity, h->llr2, long_cb);
//printf("llr2=");
//srslte_vec_fprint_f(stdout, h->llr2, long_cb);
// Update a-priori LLR from the last iteration
for (i = 0; i < long_cb; i++) {
h->w[i] += h->llr2[deinter[i]] - h->llr1[i];
}
} else {
fprintf(stderr, "Error CB index not set (call srslte_tdec_gen_reset() first\n");
}
}
int srslte_tdec_gen_reset(srslte_tdec_gen_t * h, uint32_t long_cb)
{
if (long_cb > h->max_long_cb) {
fprintf(stderr, "TDEC was initialized for max_long_cb=%d\n",
h->max_long_cb);
return -1;
}
memset(h->w, 0, sizeof(float) * long_cb);
h->current_cbidx = srslte_cbsegm_cbindex(long_cb);
if (h->current_cbidx < 0) {
fprintf(stderr, "Invalid CB length %d\n", long_cb);
return -1;
}
return 0;
}
void srslte_tdec_gen_decision(srslte_tdec_gen_t * h, uint8_t *output, uint32_t long_cb)
{
uint16_t *deinter = h->interleaver[h->current_cbidx].reverse;
uint32_t i;
for (i = 0; i < long_cb; i++) {
output[i] = (h->llr2[deinter[i]] > 0) ? 1 : 0;
}
}
void srslte_tdec_gen_decision_byte(srslte_tdec_gen_t * h, uint8_t *output, uint32_t long_cb)
{
uint32_t i;
uint8_t mask[8] = {0x80, 0x40, 0x20, 0x10, 0x8, 0x4, 0x2, 0x1};
uint16_t *deinter = h->interleaver[h->current_cbidx].reverse;
// long_cb is always byte aligned
for (i = 0; i < long_cb/8; i++) {
uint8_t out0 = h->llr2[deinter[8*i+0]]>0?mask[0]:0;
uint8_t out1 = h->llr2[deinter[8*i+1]]>0?mask[1]:0;
uint8_t out2 = h->llr2[deinter[8*i+2]]>0?mask[2]:0;
uint8_t out3 = h->llr2[deinter[8*i+3]]>0?mask[3]:0;
uint8_t out4 = h->llr2[deinter[8*i+4]]>0?mask[4]:0;
uint8_t out5 = h->llr2[deinter[8*i+5]]>0?mask[5]:0;
uint8_t out6 = h->llr2[deinter[8*i+6]]>0?mask[6]:0;
uint8_t out7 = h->llr2[deinter[8*i+7]]>0?mask[7]:0;
output[i] = out0 | out1 | out2 | out3 | out4 | out5 | out6 | out7;
}
}
int srslte_tdec_gen_run_all(srslte_tdec_gen_t * h, float * input, uint8_t *output,
uint32_t nof_iterations, uint32_t long_cb)
{
uint32_t iter = 0;
if (srslte_tdec_gen_reset(h, long_cb)) {
return SRSLTE_ERROR;
}
do {
srslte_tdec_gen_iteration(h, input, long_cb);
iter++;
} while (iter < nof_iterations);
srslte_tdec_gen_decision_byte(h, output, long_cb);
return SRSLTE_SUCCESS;
}
Reference in New Issue View Git Blame Copy Permalink