This topic has not yet been rated - Rate this topic

_mm_insert_epi8

Visual Studio 2008

Microsoft Specific

Emits the Streaming SIMD Extensions 4 (SSE4) instruction pinsrb. This instruction inserts an 8-bit integer into a 128-bit parameter.

Copy

__m128i _mm_insert_epi8( 
   __m128i a,
   int b,
   const int ndx 
);

Parameters

[in] a: A 128-bit parameter that contains sixteen 8-bit integers.
[in] b: An integer value.
[in] ndx: A constant index value that specifies the location to insert.

Result value

The result is the same as the input parameter a, except for the value at index ndx. The value at the specified index is replaced with b. This can be expressed with the following equations:

Copy

r0 := (ndx == 0) ? b : a0
r1 := (ndx == 1) ? b : a1
...
r15 := (ndx == 15) ? b : a15

Requirements

Intrinsic	Architecture
_mm_insert_epi8	x86, x64

Header file <smmintrin.h>

Remarks

r0-r15 and a0-a15 are the sequentially ordered 8-bit components of return value r and parameter a. r0 and a0 are the least significant 8 bits.

Only the lowest 8 bits of b are used.

Only the least significant 4 bits of ndx are used.

Before you use this intrinsic, software must ensure that the processor supports the instruction.

Example

Copy

#include <stdio.h>
#include <smmintrin.h>

int main ()
{
    __m128i a;
    int b = -32;
    const int ndx = 7;

    a.m128i_i8[0] = 0;
    a.m128i_i8[1] = 1;
    a.m128i_i8[2] = 2;
    a.m128i_i8[3] = 3;
    a.m128i_i8[4] = 4;
    a.m128i_i8[5] = 5;
    a.m128i_i8[6] = 6;
    a.m128i_i8[7] = 7;
    a.m128i_i8[8] = 8;
    a.m128i_i8[9] = 9;
    a.m128i_i8[10] = 10;
    a.m128i_i8[11] = 11;
    a.m128i_i8[12] = 12;
    a.m128i_i8[13] = 13;
    a.m128i_i8[14] = 14;
    a.m128i_i8[15] = 15;

    __m128i res = _mm_insert_epi8(a, b, ndx);

    printf_s("Original a:\t%4d\t%4d\t%4d\t%4d\n\t\t%4d\t%4d\t%4d\t%4d\n",
                a.m128i_i8[0], a.m128i_i8[1], a.m128i_i8[2], a.m128i_i8[3],
                a.m128i_i8[4], a.m128i_i8[5], a.m128i_i8[6], a.m128i_i8[7]);
    printf_s("\t\t%4d\t%4d\t%4d\t%4d\n\t\t%4d\t%4d\t%4d\t%4d\n\n",
                a.m128i_i8[8], a.m128i_i8[9], a.m128i_i8[10], a.m128i_i8[11],
                a.m128i_i8[12], a.m128i_i8[13], a.m128i_i8[14], a.m128i_i8[15]);

    printf_s("%d should be inserted into index %d.\n", b, ndx);
    printf_s("Result res:\t%4d\t%4d\t%4d\t%4d\n\t\t%4d\t%4d\t%4d\t%4d\n",
                res.m128i_i8[0], res.m128i_i8[1], res.m128i_i8[2], res.m128i_i8[3],
                res.m128i_i8[4], res.m128i_i8[5], res.m128i_i8[6], res.m128i_i8[7]);
    printf_s("\t\t%4d\t%4d\t%4d\t%4d\n\t\t%4d\t%4d\t%4d\t%4d\n",
                res.m128i_i8[8], res.m128i_i8[9], res.m128i_i8[10], res.m128i_i8[11],
                res.m128i_i8[12], res.m128i_i8[13], res.m128i_i8[14], res.m128i_i8[15]);

    return 0;
}

Original a: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 -32 should be inserted into index 7. Result res: 0 1 2 3 4 5 6 -32 8 9 10 11 12 13 14 15

Reference

Compiler Intrinsics

Did you find this helpful? Yes No

Not accurate

Not enough depth

Need more code examples

(1500 characters remaining)

Community Content Add

FAQ