/// <summary>
/// Schoolbook division helper function.
/// </summary>
/// <param name="n1"></param>
/// <param name="n2"></param>
/// <param name="Q">Quotient output value</param>
/// <param name="R">Remainder output value</param>
private static void Div_31(BigInt n1, BigInt n2, BigInt Q, BigInt R)
{
int digitsN1 = n1.GetMSD() + 1;
int digitsN2 = n2.GetMSD() + 1;
if ((digitsN1 > digitsN2))
{
BigInt n1New = new BigInt(n2);
n1New.DigitShiftSelfLeft(1);
//If n1 >= n2 * 2^32
if (!LtInt(n1, n1New))
{
n1New.sign = n1.sign;
SubFast(n1New, n1, n1New);
Div_32(n1New, n2, Q, R);
//Q = (A - B*2^32)/B + 2^32
Q.Add2Pow32Self();
return;
}
}
UInt32 q = 0;
if (digitsN1 >= 2)
{
UInt64 q64 = ((((UInt64)n1.digitArray[digitsN1 - 1]) << 32) + n1.digitArray[digitsN1 - 2]) / (UInt64)n2.digitArray[digitsN2 - 1];
if (q64 > 0xfffffffful)
{
q = 0xffffffff;
}
else
{
q = (UInt32)q64;
}
}
BigInt temp = Mul(n2, q);
if (GtInt(temp, n1))
{
temp.SubInternalBits(n2.digitArray);
q--;
if (GtInt(temp, n1))
{
temp.SubInternalBits(n2.digitArray);
q--;
}
}
Q.Zero();
Q.digitArray[0] = q;
R.Assign(n1);
R.SubInternalBits(temp.digitArray);
}