_mm_perm_epi8

Artigo
07/22/2011

[Note: This document describes a pre-release version of Visual Studio 2010 SP1 and may be revised in any later version.]

Visual Studio 2010 SP1 is required.

Microsoft Specific

Generates the XOP instruction vpperm to select bytes from its first two sources and optionally transform them.

__m128i _mm_perm_epi8 (
   __m128i src1,
   __m128i src2,
   __m128i selector
);

Parameters

[in] src1
A 128-bit parameter that contains sixteen bytes.
[in] src2
A 128-bit parameter that contains sixteen bytes.
[in] selector
A 128-bit parameter that selects bytes from src1 and src2 and optionally chooses a transformation to apply to the selected byte.

Return value

A 128-bit result r that contains bytes selected from src1 and src2 and is optionally transformed.

Requirements

Intrinsic	Architecture
_mm_perm_epi8	XOP

Header file <intrin.h>

Remarks

For each byte in selector, the low-order bits select a byte from src1 or src2. Values 0 to 15 select bytes 0 to 15 of src1, while values 16 to 31 select bytes 0 to 15 of src2. The high-order bits of each byte in selector determine what transformation, if any, to apply to the selected byte.

Value of high-order 3 bits of selector	Transformation chosen
000b	No transformation
001b	Invert (ones complement) source byte
010b	Bit reverse source byte
011b	Bit reverse inverted source byte
100b	Set result byte to 0x00
101b	Set result byte to 0xFF
110b	Replicate most significant bit of source byte
111b	Replicate inverted most significant bit of source byte

The vpperm instruction is part of the XOP family of instructions. Before you use this intrinsic, you must ensure that the processor supports this instruction. To determine hardware support for this instruction, call the __cpuid intrinsic with InfoType = 0x80000001 and check bit 11 of CPUInfo[2] (ECX). This bit is 1 when the instruction is supported, and 0 otherwise.

Example

#include <stdio.h>
#include <intrin.h>
int main()
{
    __m128i a, b, selector, d;
    int i;
    for (i = 15; i >= 0; i--) {
        a.m128i_u8[i] = i;               // 0x0f0e0d0c...
        b.m128i_u8[i] = (i << 4) | i;    // 0xffeeddcc...
    }
    selector.m128i_u64[1] = 0xfedcba9876543210ll;
    selector.m128i_u64[0] = 0x0011223344556677ll;
    d = _mm_perm_epi8(a, b, selector);
    printf_s("%016I64x %016I64x\n", d.m128i_u64[1], d.m128i_u64[0]);
}

00ffff009922dd00 0011fdcc20aa9f11

Change History

Date	History	Reason
March 2011	Added this content.	SP1 feature change.

March 2011

Added this content.

SP1 feature change.

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