什么是从CMP为0x4（％ESI），EBX％汇编指令为0x4意味着什么呢？ [英] What does 0x4 from cmp 0x4(%esi),%ebx assembly instruction mean?

问题描述

这是什么为0x4 从以下装配线是什么意思？

What does 0x4 from the following assembly line mean?

cmp 0x4(%esi),%ebx
je ...

在这个比较收益相等，则执行该跳中，寄存器的值：
％ESI 0xe944d6d0
％EBX 0xe94ceccc

When this compare returns equal and the jump is performed the registers have the values: %esi 0xe944d6d0 %ebx 0xe94ceccc

对不起，问这么简单的问题，但我有一个困难时期与谷歌搜索等paranthesis符号。花了超过一个半小时，而下一次pressure。

Sorry for asking such a simple question but I'm having a hard time searching such paranthesis notation with google. Spent more than half an hour while under time pressure.

推荐答案

这是AT＆amp; T公司的语法，在Intel语句这将是：

That is AT&T syntax, in Intel syntax it would be:

cmp ebx,[esi+4]

请注意该操作数的顺序是相反的。

Note that the order of operands is reversed.

在Intel语法是DEST，SRC。在AT＆安培; t将其的SRC，DEST

In Intel syntax it's dest, src. In AT&T it's src, dest.

所以基本上是指令比较 EBX 通过减去DWORD存储在 [ESI + 4] DWORD值存储在 [ESI + 4] 从 EBX ，就像分会做，但 CMP 只更新标志，它不保存任何地方的结果。

So basically that instruction compares ebx with the dword value stored in [esi+4] by subtracting the dword value stored in [esi+4] from ebx, just like sub would do, but cmp only updates flags, it doesn't store the result anywhere.

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