/* given Psi (called Lambda in Modified_Berlekamp_Massey) and synBytes,
compute the combined erasure/error evaluator polynomial as
Psi*S mod z^4
*/
void
compute_modified_omega ()
{
int i;
int product[MAXDEG*2];
mult_polys(product, Lambda, synBytes);
zero_poly(Omega);
for(i = 0; i < NPAR; i++) Omega[i] = product[i];
}
void CReedSolomon::compute_modified_omega () {
int product [MAX_LENGTH * 2];
mult_polys (product, m_Lambda, m_synBytes);
for (int i = 0; i < MAX_LENGTH; i ++) {
m_Omega [i] = 0;
}
for(int i = 0; i < m_iCorrectCodeSize; i ++) {
m_Omega [i] = product [i];
}
}
static void
compute_genpoly (int nbytes, unsigned short genpoly[])
{
unsigned short i, tp[256], tp1[256];
zero_poly(tp1);
tp1[0] = 1;
for (i = 1; i <= nbytes; i++) {
zero_poly(tp);
tp[0] = gexp[i]; /* set up x+a^n */
tp[1] = 1;
mult_polys(genpoly, tp, tp1);
copy_poly(tp1, genpoly);
}
}
static void
compute_genpoly (int nbytes, int genpoly[])
{
int i, tp[256], tp1[256];
/* multiply (x + a^n) for n = 1 to nbytes */
zero_poly(tp1);
tp1[0] = 1;
for (i = 1; i <= nbytes; i++) {
zero_poly(tp);
tp[0] = gexp[i]; /* set up x+a^n */
tp[1] = 1;
mult_polys(genpoly, tp, tp1);
copy_poly(tp1, genpoly);
}
}
void CReedSolomon::compute_genpoly (int nbytes, int genpoly []) {
int tp [MAX_LENGTH];
int tp1 [MAX_LENGTH];
/* multiply (x + a^n) for n = 1 to nbytes */
for (int i = 0; i < MAX_LENGTH; i ++) {
tp1 [i] = 0;
}
tp1 [0] = 1;
for (int i = 1; i <= nbytes; i++) {
for (int j = 0; j < MAX_LENGTH; j ++) {
tp [j] = 0;
}
tp [0] = byExpToInt [i]; /* set up x+a^n */
tp [1] = 1;
mult_polys (genpoly, tp, tp1);
for (int j = 0; j < MAX_LENGTH; j ++) {
tp1 [j] = genpoly [j];
}
}
}
// Create a generator polynomial for an n byte RS code.
void init_genpoly_cache(int par)
{
int i;
unsigned char tp[256], tp1[256];
int tmp;
unsigned char *genpoly = genpoly_cache[par-1];
//multiply (x + a^n) for n = 1 to nbytes
zero_poly(tp1, par*2);
tp1[0] = 1;
for (i = 1; i <= par; i++)
{
zero_poly(tp, par*2);
tp[0] = gexp[i]; // set up x+a^n
tp[1] = 1;
mult_polys(genpoly, tp, tp1, par*2);
copy_poly(tp1, genpoly, par*2);
}
for(i=0; i<par/2; i++)
{
tmp = genpoly[i] ;
genpoly[i] = genpoly[par-1-i];
genpoly[par-1-i]=tmp;
}
for(i=0; i<256; i++)
{
for(int j=0; j<23; j++)
genpoly_23_mult_cache[i][j] = gmult(i, genpoly_cache[22][j]);
genpoly_23_mult_cache[i][23] = 0;
}
}
