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bcjr_decoder_lut.c
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bcjr_decoder_lut.c
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#include "mex.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
/* note, the second half of the table must only be the second transition to each state */
/* last column is transition probablity */
static int transurc8[16][6] = {
{0, 0, 0, 0, 0, 0},
{1, 4, 0, 1, 0, 0},
{2, 5, 0, 1, 0, 0},
{3, 1, 0, 0, 0, 0},
{4, 6, 0, 1, 0, 0},
{5, 2, 0, 0, 0, 0},
{6, 3, 0, 0, 0, 0},
{7, 7, 0, 1, 0, 0},
{0, 4, 1, 1, 0, 0},
{1, 0, 1, 0, 0, 0},
{2, 1, 1, 0, 0, 0},
{3, 5, 1, 1, 0, 0},
{4, 2, 1, 0, 0, 0},
{5, 6, 1, 1, 0, 0},
{6, 7, 1, 1, 0, 0},
{7, 3, 1, 0, 0, 0}
};
static int translte8[16][6] = {
{1-1, 1-1, 0, 0, 0, 0},
{2-1, 5-1, 0, 0, 0, 0},
{3-1, 6-1, 0, 1, 0, 0},
{4-1, 2-1, 0, 1, 0, 0},
{5-1, 3-1, 0, 1, 0, 0},
{6-1, 7-1, 0, 1, 0, 0},
{7-1, 8-1, 0, 0, 0, 0},
{8-1, 4-1, 0, 0, 0, 0},
{1-1, 5-1, 1, 1, 0, 0},
{2-1, 1-1, 1, 1, 0, 0},
{3-1, 2-1, 1, 0, 0, 0},
{4-1, 6-1, 1, 0, 0, 0},
{5-1, 7-1, 1, 0, 0, 0},
{6-1, 3-1, 1, 0, 0, 0},
{7-1, 4-1, 1, 1, 0, 0},
{8-1, 8-1, 1, 1, 0, 0}
};
static int transurc4[16][6] = {
{1, 1, 0, 0, 0, 0},
{1, 3, 1, 1, 0, 0},
{2, 3, 0, 1, 0, 0},
{2, 1, 1, 0, 0, 0},
{3, 4, 0, 1, 0, 0},
{3, 2, 1, 0, 0, 0},
{4, 2, 0, 0, 0, 0},
{4, 4, 1, 1, 0, 0}
};
#ifndef max
#define max(a,b) \
({ __typeof__ (a) _a = (a); \
__typeof__ (b) _b = (b); \
_a > _b ? _a : _b; })
#endif
__inline double maxstar(double a, double b)
{
double diff = fabs(a-b);
double c = 0;
if (diff < 0.196)
c = 0.65;
else if (diff < 0.433)
c = 0.55;
else if (diff < 0.710)
c = 0.45;
else if (diff < 1.050)
c = 0.35;
else if (diff < 1.508)
c = 0.25;
else if (diff < 2.252)
c = 0.15;
else if (diff < 4.5)
c = 0.05;
return max(a,b) + c; /* + log(1.0+exp(-fabs(a-b))); */
}
/* reg_trellis - does each state have 2 transitions ending there? */
void bcjr_decoder(double *uncoded_in, double *coded_in1, double *coded_in2, double *coded_in3,
double *uncoded_out, double *coded_out1, double *coded_out2,double *coded_out3,
int len, int trans[][6], int state_count, int trans_count, int codeword_count,
int reg_trellis, double *trans_prob, int last_state)
{
int i,j;
int transc = trans_count;
int set0,set1;
double p1,p0;
int a,b;
double **gammas;
double **alphas;
double **betas;
double temp[16];
int states = state_count;
/* calculate gammas */
gammas = (double**) malloc (transc*sizeof(double *));
for (i = 0; i < transc; i++)
gammas[i] = (double*) malloc(len*sizeof(double));
for (i = 0; i < transc; i++)
{
if (trans[i][2] && trans[i][3]){
for (j = 0; j < len; j++){
gammas[i][j] = uncoded_in[j] + coded_in1[j];
}
}
else if (trans[i][2]){
for (j = 0; j < len; j++)
gammas[i][j] = uncoded_in[j];
}
else if (trans[i][3]){
for (j = 0; j < len; j++)
gammas[i][j] = coded_in1[j];
}
else{
for (j = 0; j < len; j++)
gammas[i][j] = 0;
}
}
if (codeword_count >= 2)
{
for (i = 0; i < transc; i++)
{
if (trans[i][4]){
for (j = 0; j < len; j++)
gammas[i][j] += coded_in2[j];
}
}
}
if (codeword_count >= 3)
{
for (i = 0; i < transc; i++)
{
if (trans[i][5]){
for (j = 0; j < len; j++)
gammas[i][j] += coded_in3[j];
}
}
}
if (trans_prob != (double*)0)
{
for (i = 0; i < transc; i++)
{
for (j=0; j < len; j++)
gammas[i][j] += trans_prob[i];
}
}
/* set and initialise memory */
alphas = (double**) malloc (states*sizeof(double *));
for (i = 0; i < states; i++)
alphas[i] = (double*) malloc(len*sizeof(double));
betas = (double**) malloc (states*sizeof(double *));
for (i = 0; i < states; i++)
betas[i] = (double*) malloc(len*sizeof(double));
if (reg_trellis == 0)
{
for (i = 0; i < states; i++) {
for (j=0; j< len; j++)
alphas[i][j] = -9000;
}
for (i = 0; i < states; i++){
for (j=0; j< len; j++)
betas[i][j] = -9000;
}
}
/* forward recursion (alphas) */
alphas[0][0] = 0; /* first state */
for (i = 1; i < states; i++)
alphas[i][0] = -9000;
if (reg_trellis == 0){
for (i = 1; i < len; i++)
{
for (j = 0; j < transc; j++)
alphas[trans[j][1]][i] = maxstar( alphas[trans[j][1]][i], alphas[trans[j][0]][i-1] + gammas[j][i-1] );
}
}
else
{
for (i = 1; i < len; i++)
{
for (j = 0; j < states; j++)
temp[trans[j][1]] = alphas[trans[j][0]][i-1] + gammas[j][i-1];
for (j = states; j < transc; j++)
alphas[trans[j][1]][i] = maxstar( temp[trans[j][1]], alphas[trans[j][0]][i-1] + gammas[j][i-1] );
}
}
/* backwards recursion (betas) */
/* double betas[8][len]; */
if (last_state < 1 || last_state > states){
for (i = 0; i < states; i++)
betas[i][len-1] = 0; /* end state unknown */
}
else
{
for (i = 0; i < states; i++)
betas[i][len-1] = -9000;
betas[last_state-1][len-1] = 0;
}
if (reg_trellis == 0){
for (i = len-2; i >= 0; i--)
{
for (j = 0; j < transc; j++)
betas[trans[j][0]][i] = maxstar( betas[trans[j][0]][i], betas[trans[j][1]][i+1] + gammas[j][i+1] );
}
}
else
{
for (i = len-2; i >= 0; i--)
{
for (j = 0; j < states; j++)
temp[trans[j][0]] = betas[trans[j][1]][i+1] + gammas[j][i+1];
for (j = states; j < transc; j++)
betas[trans[j][0]][i] = maxstar( temp[trans[j][0]], betas[trans[j][1]][i+1] + gammas[j][i+1] );
}
}
/*
* if (trans_prob != (double*)0)
* {
* mexPrintf("trans probs\n");
* for (i=0;i<transc;i++)
* {
* mexPrintf("%f ",trans_prob[i]);
*
*
* }
* }
* mexPrintf("GAMMAS\n");
* for (i=0;i<transc;i++)
* {
* for (j=0;j<len;j++)
* mexPrintf("%f ",gammas[i][j]);
* mexPrintf("\n");
*
* }
* mexPrintf("ALPHAS\n");
* for (i=0;i<states;i++)
* {
* for (j=0;j<len;j++)
* mexPrintf("%f ",alphas[i][j]);
* mexPrintf("\n");
*
* }
* mexPrintf("\n");
* mexPrintf("\n");
* mexPrintf("BETAS\n");
* for (i=0;i<states;i++)
* {
* for (j=0;j<len;j++)
* mexPrintf("%f ",betas[i][j]);
* mexPrintf("\n");
*
* }
* mexPrintf("\n");
*/
/* deltas */
/* reuse gammas memory */
for (i = 0; i < transc; i++)
{
a = trans[i][0];
b = trans[i][1];
for (j = 0; j < len; j++)
gammas[i][j] += alphas[a][j] + betas[b][j];
}
/* extrinisic uncoded llr */
for (j = 0; j < len; j++)
{
set0 = 0;
set1 = 0;
for (i = 0; i < transc; i++)
{
if (trans[i][2]){
if (set1)
p1 = maxstar(p1,gammas[i][j]);
else
{
set1 = 1;
p1 = gammas[i][j];
}
}
else{
if (set0)
p0 = maxstar(p0,gammas[i][j]);
else
{
set0 = 1;
p0 = gammas[i][j];
}
}
}
uncoded_out[j] = p1 - p0 - uncoded_in[j];
}
/* coded llr out */
for (j = 0; j < len; j++)
{
set0 = 0;
set1 = 0;
for (i = 0; i < transc; i++)
{
if (trans[i][3]){
if (set1)
p1 = maxstar(p1,gammas[i][j]);
else
{
set1 = 1;
p1 = gammas[i][j];
}
}
else{
if (set0)
p0 = maxstar(p0,gammas[i][j]);
else
{
set0 = 1;
p0 = gammas[i][j];
}
}
}
coded_out1[j] = p1 - p0 - coded_in1[j];
}
/* coded llr out2 */
if (codeword_count >= 2)
{
for (j = 0; j < len; j++)
{
set0 = 0;
set1 = 0;
for (i = 0; i < transc; i++)
{
if (trans[i][4]){
if (set1)
p1 = maxstar(p1,gammas[i][j]);
else
{
set1 = 1;
p1 = gammas[i][j];
}
}
else{
if (set0)
p0 = maxstar(p0,gammas[i][j]);
else
{
set0 = 1;
p0 = gammas[i][j];
}
}
}
coded_out2[j] = p1 - p0 - coded_in2[j];
}
}
/* coded llr out3 */
if (codeword_count >= 3)
{
for (j = 0; j < len; j++)
{
set0 = 0;
set1 = 0;
for (i = 0; i < transc; i++)
{
if (trans[i][5]){
if (set1)
p1 = maxstar(p1,gammas[i][j]);
else
{
set1 = 1;
p1 = gammas[i][j];
}
}
else{
if (set0)
p0 = maxstar(p0,gammas[i][j]);
else
{
set0 = 1;
p0 = gammas[i][j];
}
}
}
coded_out3[j] = p1 - p0 - coded_in3[j];
}
}
for (i = 0; i < transc; i++){
free(gammas[i]);
}
free(gammas);
for (i = 0; i < states; i++){
free(alphas[i]);
}
free(alphas);
for (i = 0; i < states; i++){
free(betas[i]);
}
free(betas);
}
/* The gateway function */
void mexFunction( int nlhs, mxArray *plhs[],
int nrhs, const mxArray *prhs[])
{
double *uncoded_in;
double *coded_in1;
double *coded_in2;
double *coded_in3;
double *uncoded_out;
double *coded_out1;
double *coded_out2;
double *coded_out3;
int len,i,j,states,last_state;
char *input_buf;
int blank_transitions[600][6];
double *trans_probs;
double *p;
int codeword_count = 1;
last_state = -1;
/* check for proper number of arguments */
if(nrhs<3) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:nrhs",">=Three inputs required. [uncoded_out, coded_out] = bcjr_decoder(uncoded_in, coded_in, {'urc8','urc4','lte8','uec'})");
}
if(nlhs!=2) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:nlhs","Two outputs required. [uncoded_out, coded_out] = bcjr_decoder(uncoded_in, coded_in, {'urc8','urc4','lte8','uec'})");
}
/* make sure the 1st input argument is type double */
if( !mxIsDouble(prhs[0]) ||
mxIsComplex(prhs[0])) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notDouble","Input matrix must be type double.");
}
/* make sure the 2nd input argument is type double */
if( !mxIsDouble(prhs[1]) ||
mxIsComplex(prhs[1])) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notDouble","Input matrix must be type double.");
}
/* check that number of rows in 1st input argument is 1 */
if(mxGetM(prhs[0])!=1) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notRowVector","Input must be a row vector.");
}
len = mxGetN(prhs[0]);
if (len < 3)
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notRowVector","Input must be a row vector.");
if (mxGetN(prhs[1]) < 3)
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notRowVector","Input must be a row vector.");
if (mxGetN(prhs[0]) != mxGetN(prhs[1]))
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notRowVector","Input must be same dimentions.");
input_buf = mxArrayToString(prhs[2]);
if ((strncmp(input_buf,"uec",5)==0) || (strncmp(input_buf,"new",5)==0))
{
if(nrhs!=5 && nrhs!=4)
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:nrhs","Four inputs required. [uncoded_out, coded_out] = bcjr_decoder(uncoded_in, coded_in, 'uec', transitions{, last_state}). States start at 1, set last_state < 0 for unknown");
if( !mxIsDouble(prhs[3]) ||
mxIsComplex(prhs[3])) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notDouble","Input matrix must be type double.");
}
if(mxGetM(prhs[3])==1 || mxGetM(prhs[3])>599) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notMatrix","transitions must be Tx5 (one codeword), Tx6 (two codewords) or Tx7 (two codewords). Max transitions = 600");
}
if(mxGetN(prhs[3])!=5 && mxGetN(prhs[3])!=6 && mxGetN(prhs[3])!=7) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notMatrix","transitions must be Tx5 (one codeword), Tx6 (two codewords) or Tx7 (two codewords). Max transitions = 600");
}
if(mxGetN(prhs[3])==6){
codeword_count = 2;
}
if(mxGetN(prhs[3])==7){
codeword_count = 3;
}
if (codeword_count == 2)
{
if(mxGetM(prhs[1])!=2) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notMatrix","Input coded LLRs needs two rows.");
}
}
else if (codeword_count == 3)
{
if(mxGetM(prhs[1])!=3) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notMatrix","Input coded LLRs needs threee rows.");
}
}
else
{
if(mxGetM(prhs[1])!=1) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notRowVector","Input must be a row vector.");
}
}
if(nrhs==5){
if( !mxIsDouble(prhs[4]) ||
mxIsComplex(prhs[4])) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notDouble","Input last_state must be type double.");
}
last_state = mxGetScalar(prhs[4]);
}
trans_probs = malloc(mxGetM(prhs[3])*sizeof(double *));
p = mxGetPr(prhs[3]);
for (i=0; i < 2; i++){
for (j=0; j < mxGetM(prhs[3]); j++)
blank_transitions[j][i] = ((int)*p++)-1;
}
for (i=2; i < 4; i++){
for (j=0; j < mxGetM(prhs[3]); j++)
blank_transitions[j][i] = (int)*p++;
}
if (codeword_count >= 2){
for (i=4; i < 5; i++){
for (j=0; j < mxGetM(prhs[3]); j++)
blank_transitions[j][i] = (int)*p++;
}
}
if (codeword_count >= 3){
for (i=5; i < 6; i++){
for (j=0; j < mxGetM(prhs[3]); j++)
blank_transitions[j][i] = (int)*p++;
}
}
for (i=0; i < mxGetM(prhs[3]); i++)
trans_probs[i] = *p++;
}
else
{
if(mxGetM(prhs[1])!=1) {
mexErrMsgIdAndTxt("MyToolbox:arrayProduct:notRowVector","Input must be a row vector.");
}
}
/* get pointers */
uncoded_in = mxGetPr(prhs[0]);
if (codeword_count == 1)
coded_in1 = mxGetPr(prhs[1]);
else if (codeword_count == 2)
{
coded_in1 = malloc(sizeof(double) * len);
coded_in2 = malloc(sizeof(double) * len);
p = mxGetPr(prhs[1]);
for (i=0; i < len; i++){
coded_in1[i] = *p++;
coded_in2[i] = *p++;
}
}
else if (codeword_count == 3)
{
coded_in1 = malloc(sizeof(double) * len);
coded_in2 = malloc(sizeof(double) * len);
coded_in3 = malloc(sizeof(double) * len);
p = mxGetPr(prhs[1]);
for (i=0; i < len; i++){
coded_in1[i] = *p++;
coded_in2[i] = *p++;
coded_in3[i] = *p++;
}
}
else
mexErrMsgIdAndTxt("Error","Error code: 48573869730");
/* create the output matrixs */
plhs[0] = mxCreateDoubleMatrix(1,(mwSize)len,mxREAL);
/* get a pointer to the real data in the output matrix */
uncoded_out = mxGetPr(plhs[0]);
if (codeword_count == 1){
plhs[1] = mxCreateDoubleMatrix(1,(mwSize)len,mxREAL);
coded_out1 = mxGetPr(plhs[1]);
}
else if (codeword_count == 2)
{
plhs[1] = mxCreateDoubleMatrix(2,(mwSize)len,mxREAL);
coded_out1 = malloc(sizeof(double) * len);
coded_out2 = malloc(sizeof(double) * len);
}
else if (codeword_count == 3)
{
plhs[1] = mxCreateDoubleMatrix(3,(mwSize)len,mxREAL);
coded_out1 = malloc(sizeof(double) * len);
coded_out2 = malloc(sizeof(double) * len);
coded_out3 = malloc(sizeof(double) * len);
}
else
mexErrMsgIdAndTxt("Error","Error code: 5812645");
/* call the computational routine */
if (strncmp(input_buf,"urc8",5)==0)
{
bcjr_decoder(uncoded_in, coded_in1, 0, 0,
uncoded_out, coded_out1, 0, 0, len,transurc8,8,16,1,1,(double*)0 , last_state);
}
else if (strncmp(input_buf,"urc4",5)==0)
{
bcjr_decoder(uncoded_in, coded_in1, 0, 0,
uncoded_out, coded_out1, 0, 0, len,transurc4,4,8,1,1,(double*)0 , last_state);
}
else if (strncmp(input_buf,"lte8",5)==0)
{
bcjr_decoder(uncoded_in, coded_in1, 0, 0,
uncoded_out, coded_out1, 0, 0, len,translte8,8,16,1,1,(double*)0 , last_state);
}
else if ((strncmp(input_buf,"uec",5)==0) || (strncmp(input_buf,"new",5)==0))
{
states = 0;
for (i=0;i<mxGetM(prhs[3]);i++)
{
states = max(states, blank_transitions[i][0]);
states = max(states, blank_transitions[i][1]);
}
bcjr_decoder(uncoded_in, coded_in1, coded_in2, coded_in3,
uncoded_out, coded_out1, coded_out2, coded_out3, len,blank_transitions,
states+1,mxGetM(prhs[3]),codeword_count,0,trans_probs, last_state);
free(trans_probs);
}
else
{
mexErrMsgIdAndTxt("MyToolbox:inputError","Select from 'urc8','urc4' or 'lte8'");
}
mxFree(input_buf);
if (codeword_count == 2)
{
p = mxGetPr(plhs[1]);
for (i=0; i < len; i++){
*p++ = coded_out1[i];
*p++ = coded_out2[i];
}
free(coded_in1);
free(coded_in2);
free(coded_out1);
free(coded_out2);
}
if (codeword_count == 3)
{
p = mxGetPr(plhs[1]);
for (i=0; i < len; i++){
*p++ = coded_out1[i];
*p++ = coded_out2[i];
*p++ = coded_out3[i];
}
free(coded_in1);
free(coded_in2);
free(coded_in3);
free(coded_out1);
free(coded_out2);
free(coded_out3);
}
/* mexPrintf("%f %f %f %f %f",maxstar(2.4,2.4),maxstar(6.7,8.1), maxstar(3,200), maxstar(-5,-8999), maxstar(-6.7,8.1));*/
}