Function DivideFourWordsByTwo

src/cryptopp/integer.cpp:457–477

// do a 4 word by 2 word divide, returns 2 word quotient in Q0 and Q1
template <class S, class D>
inline D DivideFourWordsByTwo(S *T, const D &Al, const D &Ah, const D &B)
{
	// Profiling tells us the original second case was dominant, so it was promoted to the first If statement.
	// The code change occurred at Commit dc99266599a0e72d.

	if (!!B)
	{
		S Q[2];
		T[0] = Al.GetLowHalf();
		T[1] = Al.GetHighHalf();
		T[2] = Ah.GetLowHalf();
		T[3] = Ah.GetHighHalf();
		Q[1] = DivideThreeWordsByTwo<S, D>(T+1, B.GetLowHalf(), B.GetHighHalf());
		Q[0] = DivideThreeWordsByTwo<S, D>(T, B.GetLowHalf(), B.GetHighHalf());
		return D(Q[0], Q[1]);
	}
	else  // if divisor is 0, we assume divisor==2**(2*WORD_BITS)
	{
		return D(Ah.GetLowHalf(), Ah.GetHighHalf());
	}
}

// returns quotient, which must fit in a word
inline word DWord::operator/(word a)