Intel® C++ Compiler Classic Developer Guide and Reference

ID 767249
Date 12/16/2022
Public

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<span class='option'>_lzcnt_u32/64 </span>

Counts the number of leading zero bits in a source operand. Returns operand size as output when source operand is zero. The corresponding Intel® AVX2 instruction is LZCNT.

Syntax

extern unsigned int _lzcnt_u32(unsigned int source);

extern unsigned __int64 _lzcnt_u64(unsigned __int64 source);

Arguments

source

the source operand used for the operation

Description

Counts the number of leading most significant zero bits in a source operand returning the result into a destination when source operand is 0.

Returns

Result of the operation.