public static void AddExt(uint[] xx, uint[] yy, uint[] zz)
{
uint c = Nat192.AddExt(xx, yy, zz);
if (c != 0 || (zz[11] == PExt11 && Nat192.GteExt(zz, PExt)))
{
Nat192.SubExt(zz, PExt, zz);
}
}