# _xrstor()/xrstors()

Restores the states of x87 FPU, MMX, XMM, YMM, and MXCSR registers from memory.

## Syntax

extern void _xrstor(void *mem, unsigned __int64 rstor_mask); extern void _xrstors(const void *mem, unsigned __int64 rstor_mask);

## Arguments

mem

  A memory reference to `FXSAVE` area. The 512-bytes memory addressed by the reference must be 16-bytes aligned.

rstor_mask

  A bit mask specifying the extended states to be restored.

## Description

Restores the states of x87 FPU, MMX, XMM, YMM, and MXCSR registers from memory. The xrstor intrinsic maps to XRSTOR instruction, and the xrstors intrinsic maps to XRSTORS instruction. See the Intel® 64 and IA-32 Architectures Software Developer's Manual for information on how the instructions differ.

Parent topic: Intrinsics for Saving and Restoring the Extended Processor States