Thread: LDPC Encoding_Showing wrong result in codeword

Hi,
I am working LDPC encoding and decoding.In Vivado HLS, I need to transform a parity-check matrix H (that only consists of ones and zeros) from a non-standard to a standard form through C/C++ programming language.

Its showing wrong result while generating codeword, please debug my program.

ISSUE : codeword, is wrong.
Codeword actual result should be [0 0 1 0 1 1] but its displaying [0 1 1 1 0 0]

this is, express it as

Hsys = [I| P]

This is my H parity check matrix

H= [1 1 0 0 1 0;
1 0 0 1 0 1;
1 1 1 0 0 1 ];

1. Arranging the parity check matrix in systematic form using row and column operations

Hsys = [I| P]

systematic parity check matrix, Hsys= [0 0 1 0 1 1
0 1 0 1 1 1;
1 0 0 1 0 1;]
2. Rearranging the systematic parity check matrix

Generator matrix G =[Ptranspose\I];

Therefore, G= [0 1 1 1 0 0 ;
1 1 0 0 1 0 ;
1 1 1 0 0 1]

3. Generate the codeword in by multiplying message with generator matrix G

c=m.G //c =codeword

Through C code, i have completed coding tasks 1 &2, but while generation codeword its showing wrong result.

for e.g. m=011
c= [011] [0 1 1 1 0 0 ;
1 1 0 0 1 0 ;
1 1 1 0 0 1]

Code:

// coding for the general form beginning using rows and cols
    int i,j,msg_length,sum=0,k;
    int message[1][10]={0};
    int rows,cols,r=0,r2,c;
    int H_Matrix[10][10]={0},code[10][10]={0};
    int temp[10][10]={0};
.................
..............
for(j=0;j<cols;j++)
    {
        printf("%d\t ",H_Matrix[i][j]);
    }
    printf("\n");
}


for (i = 0; i < 1; i++) {
      for (j = 0; j < cols; j++) {
        for (k = 0; k < rows; k++) {
          sum = sum^( message[i][k]&H_Matrix[k][j]);
        }
 
        code[i][j] = sum;
        sum = 0;
      }
    }
   
//code wrd
printf("the code word \n");   
for(i=0;i<1;i++)
{
    for(j=0;j<cols;j++)
    {
        printf("%d\t ",code[i][j]);
    }
    printf("\n");
}

Do you realize that

Code:

for (i = 0; i < 1; i++)

will run the block only once, i.e., it's as if the loop wasn't there? Maybe you want the condition to be i < 2 so the block is run twice with i as 0 and 1.

@Algorism, I have changed i=2, but its showing wrong result. Please look over the attachment.

Hi, I have got result correctly. I have did minor mistake in my code. Thanks for all your response.