NAME¶

RtlExtendedMagicDivide (NTDLL.@)

SYNOPSIS¶

#define RtlExtendedMagicDivide
( A )

DESCRIPTION¶

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".