x86中带有括号和地址的CMP [英] CMP in x86 with parentheses and address

问题描述

我在x86汇编语言中有以下一行，我不知道它的作用...

I have the following line in x86 Assembly language that I don't know what it does...

cmp %eax,0x80498d4(,%ebx,4)

我知道它正在比较语句的两半，但是我不知道地址在其中做什么以及括号在做什么.一些澄清将不胜感激！

I know it's comparing the two halves of the statement but I don't know what the address does in it and what the parentheses do either. Some clarification would be much appreciated!

推荐答案

此形式代表的AT& T语法

In AT&T syntax this form represents

偏移量(基本寄存器，索引寄存器，索引刻度)

OFFSET(BASE REGISTER, INDEX REGISTER, INDEX SCALE)

所以表示的地址是BASE REGISTER(如果存在)+ INDEX * SCALE(如果存在)+ OFFSET的值，所以

so the address represented is the value of BASE REGISTER (if present) + INDEX * SCALE (if present) + OFFSET, so

您的情况下为EBX * 4 + 0x80498d4.

EBX*4 + 0x80498d4 in your case.

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