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/*LDPC Decoder*/ #include "mex.h" #include "matrix.h" // for Matlab mx and mex fuctions #include "math.h" #include <stdlib.h> // what for #include "decodeutil_new.h" #define INF 1000 //maximum value of check_node to variable_node LLR double atanh(double x); //decode(max_iter,vhat,mrows,ncols,iter_out,gamma_n,check_node_ones,max_check_degree,BIGVALUE_COLS, // variable_node_ones,max_variable_degree,BIGVALUE_ROWS); void decode(double max_iter, double *vhat, int mrows, int ncols, double *iter_out, double *gamma_n, double *check_node_ones,double max_check_degree, double BIGVALUE_COLS, double *variable_node_ones,double max_variable_degree,double BIGVALUE_ROWS) {//function braces int i=0, j=0; double **sg_array,**sa_array, **bitmessage_temp ; double **H, **check_node_ones_matrix,**variable_node_ones_matrix; sg_array = matrix(0,mrows-1,0,ncols-1); sa_array = matrix(0,mrows-1,0,ncols-1); H = matrix(0,mrows-1,0,ncols-1); check_node_ones_matrix=matrix(0,mrows-1,0,max_check_degree-1); //for matrix from Matlab containing for each row the column indeces which are '1' variable_node_ones_matrix=matrix(0,max_variable_degree-1,0,ncols-1); for (i=0;i<max_check_degree;i++) { for(j=0;j<mrows;j++) { check_node_ones_matrix[j][i]=*(check_node_ones++); //writing out check_node_ones in 2D matrix form, from Matlab it is passed as one long vector } } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% // to print to screen the 'check_node_ones_matrix' matrix /* for ( i=0;i<mrows;i++) { mexPrintf("\n"); for( j=0;j<max_check_degree;j++) { mexPrintf("\t%f",check_node_ones_matrix[i][j]); } mexPrintf("\n"); } */ //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% for(i=0;i<ncols;i++) { for(j=0;j<max_variable_degree;j++) { variable_node_ones_matrix[j][i]=*(variable_node_ones++); } } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% // to print to screen the 'variable_node_ones_matrix' matrix /* for ( i=0;i<max_variable_degree;i++) { mexPrintf("\n"); for( j=0;j<ncols;j++) { mexPrintf("\t%f",variable_node_ones_matrix[i][j]); } mexPrintf("\n"); } */ //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% double element=0,col_index=0,row_index=0; int temp_row_index=0; //initializing the matrices for ( i=0;i<ncols;i++) { for(int j=0;j<max_variable_degree;j++) { row_index=variable_node_ones_matrix[j][i]; if(row_index==BIGVALUE_ROWS) break; temp_row_index=(int)row_index; sg_array[temp_row_index][i]=gamma_n[i]; sa_array[temp_row_index][i]=0; H[temp_row_index][i]=1; //mexPrintf("\t%f",sg_array[j][i]); } } //old way of initializing the matrices /* for ( i=0;i<ncols;i++) { for(j=0;j<mrows;j++) { sg_array[j][i]=*(sg++); //writing out sg_array in 2D matrix form, from Matlab it is passed as one long vector sa_array[j][i]=0; H[j][i]=*(h++); //writing out H in 2D matrix form, from Matlab it is passed as one long vector } }*/ //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% // to print to screen the 'H' matrix /* for ( i=0;i<mrows;i++) { mexPrintf("\n"); for(int j=0;j<ncols;j++) { mexPrintf("\t%f",H[i][j]); } mexPrintf("\n"); } */ //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% bitmessage_temp = matrix(0,mrows-1,0,ncols-1); double *sum_of_b; sum_of_b=vector(0,ncols-1); double *vhat_temp; vhat_temp =vector(0,ncols-1); for (int iteration=0;iteration<max_iter;iteration++) { //main iteration loop //bit-to-check messages for ( i=0;i<mrows;i++) { for (j=0;j<max_check_degree;j++) { col_index=check_node_ones_matrix[i][j]; if (col_index==BIGVALUE_COLS) // if element is value put in to fill zeros, then break { break; } bitmessage_temp[i][(int)col_index]=tanh ( ( -(sg_array[i][(int)col_index]) + sa_array[i][(int)col_index] ) / 2 ); } } //check-to-bit-messages for (int u=0;u<mrows;u++) {//across mrows double temp=1; for (int v =0;v<max_check_degree;v++) {//across columns element=check_node_ones_matrix[u][v]; // this is value of column in H which has '1' for this row if (element==BIGVALUE_COLS) // if element is value put in to fill zeros, then break { break; } for (int w=0;w<max_check_degree;w++) {//accross columns again col_index=check_node_ones_matrix[u][w]; if(check_node_ones_matrix[u][w]!=element && check_node_ones_matrix[u][w]!=BIGVALUE_COLS) {//second if temp=temp* bitmessage_temp[u][(int)col_index]; }//second if }//accross columns again sa_array[u][(int)element]=-2*atanh(temp); temp=1; }//across columns }//accross mrows //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% // to print to screen the 'sa_array' matrix /* for ( i=0;i<mrows;i++) { mexPrintf("\n"); for(int j=0;j<ncols;j++) { mexPrintf("\t%f",sa_array[i][j]); } mexPrintf("\n"); } */ //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% //sum across columns for ( i=0;i<ncols;i++) { double temp=0; for(int j=0;j<max_variable_degree;j++) { row_index=variable_node_ones_matrix[j][i]; if(row_index==BIGVALUE_ROWS) break; temp=temp+sa_array[(int)row_index][i];//sa_array is equal to old bitmessage_2 } sum_of_b[i]=temp; } //update the APP LLR and hard decision for ( i=0;i<ncols;i++) { for(int j=0;j<max_variable_degree;j++) { row_index=variable_node_ones_matrix[j][i]; if(row_index==BIGVALUE_ROWS) break; sg_array[(int)row_index][i]=sum_of_b[i]+gamma_n[i]; //mexPrintf("\t%f",sg_array[j][i]); } vhat_temp[i]=sum_of_b[i]+gamma_n[i]; //hard decision if (vhat_temp[i]>=0) *(vhat+i)=1; else *(vhat+i)=0; //mexPrintf("\n\t vhat is :%f\t",*(vhat+i)); } //check if valid codeword int parity=0,cumsum=0; for ( j=0;j<mrows;j++) { for (i=0;i<ncols;i++) //multiply codeword with row of H { *(vhat_temp+i)=H[j][i]* *(vhat+i); } parity=0; for(i=0;i<ncols;i++) { parity=(parity + (int)(*(vhat_temp+i)) )%2; } //mexPrintf("\n\tparity is :%d\t",parity); cumsum=parity+cumsum; //mexPrintf("\n\tInput cumsum is :%f\t",cumsum); if (cumsum==1) //will happen when parity is 1: means not valid codeword, so continue with iterations { break; } } if (cumsum==0) //valid codeword { *iter_out=iteration+1; return; } } //main iteration loop *iter_out=iteration; }//function braces double atanh(double x) { double epsilon; epsilon = pow(10,-16); if(x>(1-epsilon)) return INF; if(x<(-1+epsilon)) return -INF; return 0.5*log((1+x)/(1-x)); } // new 0 1 2 3 4 5 6 //vhat=decode_ldpc_new(max_iter,gamma_n,check_node_ones,max_check_degree,BIGVALUE_COLS-1,variable_node_ones,max_variable_degree, // 7 8 9 //BIGVALUE_ROWS-1,rows,cols); void mexFunction( int nlhs, mxArray *plhs[], int nrhs, const mxArray*prhs[] ) { double *vhat, *iter_out,*gamma_n, *check_node_ones, *variable_node_ones; /*pointer variables for input Matrices*/ double max_iter,max_check_degree,max_variable_degree, BIGVALUE_COLS,BIGVALUE_