ARM霓虹灯：条件存储建议 [英] ARM Neon: conditional store suggestion

问题描述

我想弄清楚如何生成ARM霓虹灯有​​条件的商店。我想这样做是这样的SSE指令等价的：

无效_mm_maskmoveu_si128（__ m128i D，__m128i N，字符* P）;

该有条件将Byte d可应对选择n均为字节p.The高位的因素决定D中的相应字节是否将被保存。

如何与NEON内在做任何建议？
谢谢

这是我做过什么：

  int8x16_t store_mask = {0,0,0,0,0,0,0xff，为0xFF，0xFF的，为0xFF，0xFF的，为0xFF，0xFF的，为0xFF，0xFF的，0xFF的};int8x16_t tmp_dest = vld1q_u8（（*中int8_t）p_dest）;
vbslq_u8（源，tmp_dest，store_mask）;
vst1q_u8（（*中int8_t）p_dest，tmp_dest）;
 

解决方案

假设16×1字节元素的向量，你将建立一个面具向量，其中每个元素是全0（ 0×00 ）或全1（ 0xFF的），以确定该元素是否应该被存放​​在没有。然后，你需要做以下（伪code）：

 的init遮罩向量= 0×00 /中的每个元素为0xFF
 初始化源向量=被选择性地存储的数据
 从DEST位置加载DEST载体
 适用`与DEST载体，源矢量和掩码矢量vbslq_u8`（`vbit`指令）
 店内DEST载体回DEST位置
 

I'm trying to figure out how to generate a conditional Store in ARM neon. What I would like to do is the equivalent of this SSE instruction:

void _mm_maskmoveu_si128(__m128i d, __m128i n, char *p);

which Conditionally stores byte elements of d to address p.The high bit of each byte in the selector n determines whether the corresponding byte in d will be stored.

Any suggestion on how to do it with NEON intrinsics? Thank you

This is what I did:

int8x16_t store_mask = {0,0,0,0,0,0,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff};

int8x16_t tmp_dest = vld1q_u8((int8_t*)p_dest);
vbslq_u8(source,tmp_dest,store_mask);
vst1q_u8((int8_t*)p_dest,tmp_dest);

解决方案

Assuming vectors of 16 x 1 byte elements, you would set up a mask vector where each element is either all 0s (0x00) or all 1s (0xff) to determine whether the element should be stored on not. Then you need to do the following (pseudo code):

 init mask vector = 0x00/0xff in each element
 init source vector = data to be selectively stored
 load dest vector from dest location
 apply `vbslq_u8` (`vbit` instruction) with dest vector, source vector and mask vector
 store dest vector back to dest location

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