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_mm_shl_epi32

Visual Studio 2010

Visual Studio 2010 SP1 is required.

Microsoft Specific

Generates the XOP instruction vpshld to do a logical shift of each of the doublewords in its first source by an amount specified in the second.

__m128i _mm_shl_epi32 (
   __m128i src,
   __m128i counts
);

[in] src

A 128-bit parameter that contains four 32-bit unsigned integers.

[in] counts

A 128-bit parameter that contains sixteen 8-bit signed integers.

A 128-bit result r that contains four 32-bit unsigned integers.

r[i] := (counts[4*i] >= 0) ? src[i] << counts[4*i] :
                             src[i] >> -counts[4*i]);

Intrinsic

Architecture

_mm_shl_epi32

XOP

Header file <intrin.h>

Each 32-bit unsigned integer value in src is shifted by the number of bits specified by the value in the byte of counts corresponding to its low-order byte, and the 32-bit unsigned integer result is stored as the corresponding value in the destination. If the value in counts is positive, the shift is to the left (toward the most significant bit) and zeros are shifted in at the right end; otherwise, it is to the right and zeros are shifted in at the left end. If a shift count is greater than 31 or less than -31, the corresponding result value is 0. The other values in counts are ignored.

The vpshld 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.

#include <stdio.h>
#include <intrin.h>
int main()
{
    __m128i a, b, d;
    int i, j;
    unsigned int temp;
    for (i = 0; i < 4; i++) {
        temp = 0;
        for (j = 0; j < 8; j++) {
            temp = temp << 4 | (8*i + j + 7) % 16;
        }
        a.m128i_u32[i] = temp;
        b.m128i_i8[4*i] = 11*i - 21;
    }
    d = _mm_shl_epi32(a, b);
    printf_s("data:       ");
    for (i = 0; i < 4; i++) printf_s(" %08x", a.m128i_u32[i]);
    printf_s("\nshifted by  ");
    for (i = 0; i < 4; i++) printf_s(" %8d", b.m128i_i8[4*i]);
    printf_s("\ngives       ");
    for (i = 0; i < 4; i++) printf_s(" %08x", d.m128i_u32[i]);
    printf_s("\n");
}
data:        789abcde f0123456 789abcde f0123456
shifted by        -21      -10        1       12
gives        000003c4 003c048d f13579bc 23456000
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