/// <summary>
/// Schoolbook division algorithm
/// </summary>
/// <param name="n1"></param>
/// <param name="n2"></param>
/// <param name="Q"></param>
/// <param name="R"></param>
private static void Div_32(BigInt n1, BigInt n2, BigInt Q, BigInt R)
{
int digitsN1 = n1.GetMSD() + 1;
int digitsN2 = n2.GetMSD() + 1;
//n2 is bigger than n1
if (digitsN1 < digitsN2)
{
R.AssignInt(n1);
Q.Zero();
return;
}
if (digitsN1 == digitsN2)
{
//n2 is bigger than n1
if (LtInt(n1, n2))
{
R.AssignInt(n1);
Q.Zero();
return;
}
//n2 >= n1, but less the 2x n1 (initial conditions make this certain)
Q.Zero();
Q.digitArray[0] = 1;
R.Assign(n1);
R.SubInternalBits(n2.digitArray);
return;
}
int digits = digitsN1 - (digitsN2 + 1);
//Algorithm Div_31 can be used to get the answer in O(n) time.
if (digits == 0)
{
Div_31(n1, n2, Q, R);
return;
}
BigInt n1New = DigitShiftRight(n1, digits);
BigInt s = DigitTruncate(n1, digits);
BigInt Q2 = new BigInt(n1, n1.pres, true);
BigInt R2 = new BigInt(n1, n1.pres, true);
Div_31(n1New, n2, Q2, R2);
R2.DigitShiftSelfLeft(digits);
R2.Add(s);
Div_32(R2, n2, Q, R);
Q2.DigitShiftSelfLeft(digits);
Q.Add(Q2);
}
