在寄存器中获取MSB/LSB

本文介绍了在寄存器中获取MSB/LSB的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

这似乎是一个愚蠢的问题，但我无法真正说出我所缺少的内容

This might seem like a stupid question, but I cant really tell what I'm missing

在ARM 7上:

我说寄存器0中有一个8位数字

I have a 8 digit number in register 0, say

10110111

我想循环浏览并用当前位做一些事情，直到8位上升为止，但是我在解决这个简单问题上遇到了很多麻烦.

I want to 'loop' through this and do something with the current bit until the 8 bits are up, but I'm having alot of trouble with this simple issue..

我的逻辑是:

- get MSB / LSB of number in r0 - shift it to r1 - lsl / lsr r0

但是根据这种逻辑，我不知道您将如何获得MSB/LSB.有人可以帮我吗?还是有更好的方法来遍历这一点?

But from this logic, I dont know how you would get the MSB / LSB. Could anyone help me out? Or is there a better way of looping through this?

谢谢！

推荐答案

查看rbit和clz指令.这些使您可以计算MSB和LSB索引.

Check out the rbit and clz instructions. These allow you to compute the MSB and LSB index.