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Use IsPowerOf2 in Integer::Divide

pull/795/head
Jeffrey Walton 2019-02-05 02:05:36 -05:00
parent b09ca89a6e
commit 48531785b7
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GPG Key ID: B36AB348921B1838
1 changed files with 3 additions and 1 deletions
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integer.cpp
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@ -4244,7 +4244,9 @@ void Integer::Divide(word &remainder, Integer &quotient, const Integer &dividend
if (!divisor)
throw Integer::DivideByZero();
if ((divisor & (divisor-1)) == 0) // divisor is a power of 2
// IsPowerOf2 uses BMI on x86 if available. There is a small
// but measurable improvement during decryption and signing.
if (IsPowerOf2(divisor))
{
quotient = dividend >> (BitPrecision(divisor)-1);
remainder = dividend.reg[0] & (divisor-1);