void CReedSolomon::Modified_Berlekamp_Massey (void) {
int L, L2, k, d;
int psi [MAX_LENGTH], psi2 [MAX_LENGTH], D [MAX_LENGTH];
int gamma [MAX_LENGTH];
int iMaxLength = m_iCorrectCodeSize * 2;
/* initialize Gamma, the erasure locator polynomial */
init_gamma (gamma);
/* initialize to z */
copy_poly (D, gamma);
mul_z_poly (D);
copy_poly (psi, gamma);
k = -1;
L = m_NErasures;
for (int n = m_NErasures; n < m_iCorrectCodeSize; n ++) {
d = compute_discrepancy (psi, m_synBytes, L, n);
if (d != 0) {
/* psi2 = psi - d*D */
for (int i = 0; i < iMaxLength; i++) {
psi2 [i] = psi [i] ^ gmult (d, D [i]);
}
if (L < (n - k)) {
L2 = n - k;
k = n - L;
/* D = scale_poly(ginv(d), psi); */
for (int i = 0; i < iMaxLength; i ++) {
D [i] = gmult (psi [i], ginv (d));
}
L = L2;
}
/* psi = psi2 */
for (int i = 0; i < iMaxLength; i ++) {
psi [i] = psi2 [i];
}
}
mul_z_poly (D);
}
for (int i = 0; i < MAX_LENGTH; i ++) {
m_Lambda [i] = psi [i];
}
compute_modified_omega ();
}
/* From Cain, Clark, "Error-Correction Coding For Digital Communications", pp. 216. */
void
Modified_Berlekamp_Massey (void)
{
int n, L, L2, k, d, i;
int psi[MAXDEG], psi2[MAXDEG], D[MAXDEG];
int gamma[MAXDEG];
/* initialize Gamma, the erasure locator polynomial */
init_gamma(gamma);
/* initialize to z */
copy_poly(D, gamma);
mul_z_poly(D);
copy_poly(psi, gamma);
k = -1;
L = NErasures;
for (n = NErasures; n < NPAR; n++) {
d = compute_discrepancy(psi, synBytes, L, n);
if (d != 0) {
/* psi2 = psi - d*D */
for (i = 0; i < MAXDEG; i++) psi2[i] = psi[i] ^ gmult(d, D[i]);
if (L < (n-k)) {
L2 = n-k;
k = n-L;
/* D = scale_poly(ginv(d), psi); */
for (i = 0; i < MAXDEG; i++) D[i] = gmult(psi[i], ginv(d));
L = L2;
}
/* psi = psi2 */
for (i = 0; i < MAXDEG; i++) psi[i] = psi2[i];
}
mul_z_poly(D);
}
for(i = 0; i < MAXDEG; i++) Lambda[i] = psi[i];
compute_modified_omega();
}
