_mm_stream_ss

Article
06/05/2017

The new home for Visual Studio documentation is Visual Studio 2017 Documentation on docs.microsoft.com.

The latest version of this topic can be found at _mm_stream_ss.

Microsoft Specific**

Writes 32-bit data to a memory location without polluting the caches.

Syntax

void _mm_stream_ss(  
   float * Dest,  
   __m128 Source  
);

Parameters

[out] Dest
A pointer to the location where the source data is written.

[in] Source
A 128-bit number that contains the float value to be written in its bottom 32 bits..

Return Value

None.

Requirements

Intrinsic	Architecture
`_mm_stream_ss`	SSE4a

Header file <intrin.h>

Remarks

This intrinsic generates the movntss instruction. To determine hardware support for this instruction, call the __cpuid intrinsic with InfoType=0x80000001and check bit 6 of CPUInfo[2] (ECX). This bit is 1 when the instruction is supported, and 0 otherwise.

If you run code that uses the _mm_stream_ss intrinsic on hardware that does not support the movntss instruction, the results are unpredictable.

Example

// Compile this sample with: /EHsc  
#include <iostream>  
#include <intrin.h>  
using namespace std;  
  
int main()  
{  
    __m128 vals;  
    float f[4];  
  
    f[0] = -1.;  
    f[1] = -2.;  
    f[2] = -3.;  
    f[3] = -4.;  
    vals.m128_f32[0] = 0.;  
    vals.m128_f32[1] = 1.;  
    vals.m128_f32[2] = 2.;  
    vals.m128_f32[3] = 3.;  
    _mm_stream_ss(&f[3], vals);  
    cout << "f[0] = " << f[0] << ", f[1] = " << f[1] << endl;  
    cout << "f[1] = " << f[1] << ", f[3] = " << f[3] << endl;  
}

f[0] = -1, f[1] = -2  
f[2] = -3, f[3] = 3

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