# _xsetbv()

Writes the given value to a specified extended control register.

## Syntax

extern void _xsetbv(unsigned int xcr, unsigned __int64 val);

## Arguments

xcr

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

val

  Value to be written to the specified extended control register.

## Description

This intrinsic writes the given value to the specified extended control register. 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 XSETBV instruction.
Parent topic: Intrinsics for Reading and Writing the Content of Extended Control Registers