SSE:将短整数转换为浮点数 [英] SSE: convert short integer to float

问题描述

我想使用 SSE 将一组无符号短数转换为浮点数.说吧

I want to convert an array of unsigned short numbers to float using SSE. Let's say

__m128i xVal;     // Has 8 16-bit unsigned integers
__m128 y1, y2;    // 2 xmm registers for 8 float values

我想要 y1 中的前 4 个 uint16 &y2 中的下一个 4 uint16.需要知道使用哪个 sse 内在的.

I want first 4 uint16 in y1 & next 4 uint16 in y2. Need to know which sse intrinsic to use.

推荐答案

您需要先将 8 x 16 位无符号短整型向量解包为两个 32 位无符号整数向量，然后将这些向量中的每一个都转换为浮点型:

You need to first unpack your vector of 8 x 16 bit unsigned shorts into two vectors of 32 bit unsigned ints, then convert each of these vectors to float:

__m128i xlo = _mm_unpacklo_epi16(x, _mm_set1_epi16(0));
__m128i xhi = _mm_unpackhi_epi16(x, _mm_set1_epi16(0));
__m128 ylo = _mm_cvtepi32_ps(xlo);
__m128 yhi = _mm_cvtepi32_ps(xhi);

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