/// <summary>
/// Tests all trinomials of degree (n+1) until a irreducible is found and stores the result in <c>field polynomial</c>.
/// Returns false if no irreducible trinomial exists in GF(2^n). This can take very long for huge degrees.
/// </summary>
///
/// <returns>Returns true if an irreducible trinomial is found</returns>
private bool TestTrinomials()
{
int i, l;
bool done = false;
l = 0;
FieldPoly = new GF2Polynomial(DegreeN + 1);
FieldPoly.SetBit(0);
FieldPoly.SetBit(DegreeN);
for (i = 1; (i < DegreeN) && !done; i++)
{
FieldPoly.SetBit(i);
done = FieldPoly.IsIrreducible();
l++;
if (done)
{
_isTrinomial = true;
_tc = i;
return done;
}
FieldPoly.ResetBit(i);
done = FieldPoly.IsIrreducible();
}
return done;
}
/// <summary>
/// Tests all pentanomials of degree (n+1) until a irreducible is found and stores the result in <c>field polynomial</c>.
/// Returns false if no irreducible pentanomial exists in GF(2^n).
/// This can take very long for huge degrees.
/// </summary>
///
/// <returns>Returns true if an irreducible pentanomial is found</returns>
private bool TestPentanomials()
{
int i, j, k, l;
bool done = false;
l = 0;
FieldPoly = new GF2Polynomial(DegreeN + 1);
FieldPoly.SetBit(0);
FieldPoly.SetBit(DegreeN);
for (i = 1; (i <= (DegreeN - 3)) && !done; i++)
{
FieldPoly.SetBit(i);
for (j = i + 1; (j <= (DegreeN - 2)) && !done; j++)
{
FieldPoly.SetBit(j);
for (k = j + 1; (k <= (DegreeN - 1)) && !done; k++)
{
FieldPoly.SetBit(k);
if (((DegreeN & 1) != 0) | ((i & 1) != 0) | ((j & 1) != 0)
| ((k & 1) != 0))
{
done = FieldPoly.IsIrreducible();
l++;
if (done)
{
_isPentanomial = true;
_pc[0] = i;
_pc[1] = j;
_pc[2] = k;
return done;
}
}
FieldPoly.ResetBit(k);
}
FieldPoly.ResetBit(j);
}
FieldPoly.ResetBit(i);
}
return done;
}