英文:

Split 16-bit vector (__m128i) into 2 vectors of odd and even positions with Intel intrinsics

问题

__m128i a = {1,2,3,4,5,6,7,8}; //8x16bit

我想将这个寄存器分成两个包含4x32bit的向量：
```c
__m128i x = {1,3,5,7}
__m128i y = {2,4,6,8} 

使用内置代码是否可能？

在RAM中，我有16位字的原始数据。例如：1,2,3,4,5,6,7,8
目标是将此流分成实部（1,3,5,7）和虚部（2,4,6,8）。

<details>
<summary>英文:</summary>

    __m128i a = {1,2,3,4,5,6,7,8}; //8x16bit

I want to split this register into 2 vectors each contains 4x32bit :

__m128i x = {1,3,5,7}
__m128i y = {2,4,6,8}

Is it possible with intrinsic code ?

In RAM, I have raw data of 16bits words. e.g: 1,2,3,4,5,6,7,8
The goal is to split this stream into real part (1,3,5,7) and imaginary part (2,4,6,8)

</details>


# 答案1
**得分**: 2

```c
假设您已将所有内容加载到`__m128i`中，并且正在处理带符号整数，我认为最简单的方法是：

```c
__m128i x = _mm_srai_epi32(_mm_slli_epi32(a, 16), 16);
__m128i y = _mm_srai_epi32(a, 16);

对于无符号整数，如Peter在评论中提到的：

__m127i x = _mm_and_si128(v, _mm_set1_epi32(0x0000FFFF));
__m128i y = _mm_srli_epi32(a, 16);

<details>
<summary>英文:</summary>

Assuming you have everything loaded into an `__m128i` and you&#39;re dealing with signed integers, I think the easiest way would be:

```c
__m128i x = _mm_srai_epi32(_mm_slli_epi32(a, 16), 16);
__m128i y = _mm_srai_epi32(a, 16);

For unsigned integers, as Peter mentioned in the comments:

__m127i x = _mm_and_si128(v, _mm_set1_epi32(0x0000FFFF));
__m128i y = _mm_srli_epi32(a, 16);