_mm_insert_si64, _mm_inserti_si64

Article
08/03/2021

Microsoft Specific

Generates the insertq instruction to insert bits from its second operand into its first operand.

Syntax

__m128i _mm_insert_si64(
   __m128i Source1,
   __m128i Source2
);
__m128i _mm_inserti_si64(
   __m128i Source1,
   __m128i Source2
   int Length,
   int Index
);

Parameters

Source1
[in] A 128-bit field that has input data in its lower 64 bits, into which a field will be inserted.

Source2
[in] A 128-bit field that has the data to insert in its low bits. For _mm_insert_si64, also contains a field descriptor in its high bits.

Length
[in] An integer constant that specifies the length of the field to insert.

Index
[in] An integer constant that specifies the index of the least significant bit of the field into which data will be inserted.

Return value

A 128-bit field, whose lower 64 bits contain the original low 64 bits of Source1, with the specified bit field replaced by the low bits of Source2. The upper 64 bits of the return value are undefined.

Requirements

Intrinsic	Architecture
`_mm_insert_si64`	SSE4a
`_mm_inserti_si64`	SSE4a

Header file <intrin.h>

Remarks

These intrinsics generate the insertq instruction to insert bits from Source2 into Source1. There are two versions: _mm_inserti_si64, is the immediate version, and _mm_insert_si64 is the non-immediate one. Each version extracts a bit field of a given length from Source2 and inserts it into Source1. The extracted bits are the least significant bits of Source2. The field Source1 into which these bits will be inserted is defined by the length and the index of its least significant bit. The values of the length and index are taken mod 64, so both -1 and 127 are interpreted as 63. If the sum of the (reduced) bit index and (reduced) field length is larger than 64, the results are undefined. A value of zero for field length is interpreted as 64. If the field length and bit index are both zero, bits 63:0 of Source2 are inserted into Source1. If the field length is zero, but the bit index is non-zero, the results are undefined.

In a call to _mm_insert_si64, the field length is contained in bits 77:72 of Source2 and the index in bits 69:64.

If you call _mm_inserti_si64 with arguments that the compiler can't determine to be integer constants, the compiler generates code to pack those values into an XMM register and to call _mm_insert_si64.

To determine hardware support for the insertq instruction, call the __cpuid intrinsic with InfoType=0x80000001 and check bit 6 of CPUInfo[2] (ECX). This bit is 1 if the instruction is supported, and 0 otherwise. If you run code that uses the intrinsic on hardware that doesn't support the insertq instruction, the results are unpredictable.

Example

// Compile this sample with: /EHsc
#include <iostream>
#include <intrin.h>
using namespace std;

union {
    __m128i m;
    unsigned __int64 ui64[2];
} source1, source2, source3, result1, result2, result3;

int
main()
{

    __int64 mask;

    source1.ui64[0] = 0xffffffffffffffffll;
    source2.ui64[0] = 0xfedcba9876543210ll;
    source2.ui64[1] = 0xc10;
    source3.ui64[0] = source2.ui64[0];

    result1.m = _mm_insert_si64 (source1.m, source2.m);
    result2.m = _mm_inserti_si64(source1.m, source3.m, 16, 12);
    mask = 0xffff << 12;
    mask = ~mask;
    result3.ui64[0] = (source1.ui64[0] & mask) |
                      ((source2.ui64[0] & 0xffff) << 12);

    cout << hex << "result1 = 0x" << result1.ui64[0] << endl;
    cout << "result2 = 0x" << result2.ui64[0] << endl;
    cout << "result3 = 0x" << result3.ui64[0] << endl;

}

result1 = 0xfffffffff3210fff
result2 = 0xfffffffff3210fff
result3 = 0xfffffffff3210fff

END Microsoft Specific

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