RtlExtendedMagicDivide3w

Usage

Overview

Allows replacing a division by a longlong constant with a multiplication by the inverse constant.

Returns

(dividend * inverse_divisor) >> (64 + shift).

Notes

If the divisor of a division is constant, the constants inverse_divisor and shift must be chosen such that inverse_divisor = 2^(64 + shift) / divisor. Then we have RtlExtendedMagicDivide(dividend,inverse_divisor,shift) == dividend * inverse_divisor / 2^(64 + shift) == dividend / divisor.

The Parameter inverse_divisor although defined as LONGLONG is used as ULONGLONG.

Implementation

Declared in "winternl.h".

Implemented in "dlls/ntdll/large_int.c".