Atmel Evaluation Kit AT91SAM9X35-EK AT91SAM9X35-EK Data Sheet

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SAM9X35 [DATASHEET]

11055E–ATARM–10-Mar-2014

NB_ERROR_MAX defines the maximum value of the error correcting capability.

NB_ERROR defines the error correcting capability selected at encoding/decoding time.

NB_FIELD_ELEMENTS defines the number of elements in the field.

si[] is a table that holds the current syndrome value, an element of that table belongs to the field. This is also a shared
variable for the next step of the decoding operation.

oo[] is a table that contains the degree of the remainders.

int substitute()

{

int i;

int j;

for (i = 1; i < 2 * NB_ERROR_MAX; i++)

{

si[i] = 0;

}

for (i = 1; i < 2*NB_ERROR; i++)

{

for (j = 0; j < oo[i]; j++)

{

if (REM2NPX[i][j])

{

si[i] = gf_antilog[(i * j)%NB_FIELD_ELEMENTS] ^ si[i];

}

}

}

return 0;

}

The sample code below gives a Berlekamp iterative procedure for finding the value of the error location polynomial.

The input of the procedure is the si[] table defined in the remainder substitution procedure.

The output of the procedure is the error location polynomial named smu (sigma mu). The polynomial coefficients belong
to the field. The smu[NB_ERROR+1][] is a table that contains all these coefficients.

NB_ERROR_MAX defines the maximum value of the error correcting capability.

NB_ERROR defines the error correcting capability selected at encoding/decoding time.

NB_FIELD_ELEMENTS defines the number of elements in the field.

int get_sigma()
{
int i;
int j;
int k;
/* mu          */
int mu[NB_ERROR_MAX+2];
/* sigma ro   */
int sro[2*NB_ERROR_MAX+1];
/* discrepancy */
int dmu[NB_ERROR_MAX+2];
/* delta order   */
int delta[NB_ERROR_MAX+2];
/* index of largest delta */
int ro;
int largest;
int diff;
/*                    */