/**
* Computes the inverse mod q from the inverse mod 2
*
* @param Fq
* @param q
* @return The inverse of this polynomial mod q
*/
private IntegerPolynomial Mod2ToModq(IntegerPolynomial Fq, int q)
{
//if (Util.is64BitJVM() && q == 2048)
if (true && q == 2048)
{
LongPolynomial2 thisLong = new LongPolynomial2(this);
LongPolynomial2 FqLong = new LongPolynomial2(Fq);
int v = 2;
while (v < q)
{
v *= 2;
LongPolynomial2 temp = (LongPolynomial2)FqLong.Clone();
temp.mult2And(v - 1);
FqLong = thisLong.Multiply(FqLong).Multiply(FqLong);
temp.SubAnd(FqLong, v - 1);
FqLong = temp;
}
return(FqLong.ToIntegerPolynomial());
}
else
{
int v = 2;
while (v < q)
{
v *= 2;
int[] copy = new int[Fq.coeffs.Length];
Array.Copy(Fq.coeffs, copy, Fq.coeffs.Length);
IntegerPolynomial temp = new IntegerPolynomial(copy);
temp.Multiply2(v);
Fq = Multiply(Fq, v).Multiply(Fq, v);
temp.Sub(Fq, v);
Fq = temp;
}
return(Fq);
}
}
/**
* Karazuba multiplication
*/
private LongPolynomial2 MultiplyRecursive(LongPolynomial2 poly2)
{
long[] a = coeffs;
long[] b = poly2.coeffs;
int n = poly2.coeffs.Length;
if (n <= 32)
{
int cn = 2 * n;
LongPolynomial2 c = new LongPolynomial2(new long[cn]);
for (int k = 0; k < cn; k++)
{
for (int i = System.Math.Max(0, k - n + 1); i <= System.Math.Min(k, n - 1); i++)
{
long c0 = a[k - i] * b[i];
long cu = c0 & 0x7FF000000L + (c0 & 2047);
long co = (c0.UnsignedRightShift(48)) & 2047; //>>> 48
c.coeffs[k] = (c.coeffs[k] + cu) & 0x7FF0007FFL;
c.coeffs[k + 1] = (c.coeffs[k + 1] + co) & 0x7FF0007FFL;
}
}
return(c);
}
else
{
int n1 = n / 2;
long[] a1Temp = new long[n1];
long[] a2Temp = new long[n - n1];
long[] b1Temp = new long[n1];
long[] b2Temp = new long[n - n1];
Array.Copy(a, a1Temp, n1);
Array.Copy(a, n1, a2Temp, 0, n - n1);
Array.Copy(b, b1Temp, n1);
Array.Copy(b, n1, b2Temp, 0, n - n1);
LongPolynomial2 a1 = new LongPolynomial2(a1Temp);
LongPolynomial2 a2 = new LongPolynomial2(a2Temp);
LongPolynomial2 b1 = new LongPolynomial2(b1Temp);
LongPolynomial2 b2 = new LongPolynomial2(b2Temp);
LongPolynomial2 A = (LongPolynomial2)a1.Clone();
A.Add(a2);
LongPolynomial2 B = (LongPolynomial2)b1.Clone();
B.Add(b2);
LongPolynomial2 c1 = a1.MultiplyRecursive(b1);
LongPolynomial2 c2 = a2.MultiplyRecursive(b2);
LongPolynomial2 c3 = A.MultiplyRecursive(B);
c3.Sub(c1);
c3.Sub(c2);
LongPolynomial2 c = new LongPolynomial2(2 * n);
for (int i = 0; i < c1.coeffs.Length; i++)
{
c.coeffs[i] = c1.coeffs[i] & 0x7FF0007FFL;
}
for (int i = 0; i < c3.coeffs.Length; i++)
{
c.coeffs[n1 + i] = (c.coeffs[n1 + i] + c3.coeffs[i]) & 0x7FF0007FFL;
}
for (int i = 0; i < c2.coeffs.Length; i++)
{
c.coeffs[2 * n1 + i] = (c.coeffs[2 * n1 + i] + c2.coeffs[i]) & 0x7FF0007FFL;
}
return(c);
}
}