# _xgetbv()

Reads the content of an extended control register.

## Syntax

extern unsigned __int64 _xgetbv(unsigned int xcr);

## Arguments

xcr

  An extended control register to be read. Currently, only the value '0' is allowed.

## Description

This intrinsic reads from extended control registers. Currently, the only control register allowed/defined is (XCR0) XFEATURE_ENABLED_MASK register. The corresponding constant is defined in the immintrin.h file to refer to this register:

    #define _XCR_XFEATURE_ENABLED_MASK 0

This intrinsic maps to XGETBV instruction.

## Returns

Returns the content of a specified extended control register.

Parent topic: Intrinsics for Reading and Writing the Content of Extended Control Registers