为什么存储在存储器中的数据被颠倒了? [英] Why is data stored in memory reversed?

问题描述

这是我拥有的源代码:

section .data           
msg:    db "pppaaa"     
len:    equ $
section .text           
    global  main    
main:                    
    mov     edx,len 
    mov     ecx,msg 
    mov     ebx,1   
    mov     eax,4   
    int     0x80

当我调试此代码时，我会看到:

And when I debug this code I will see:

(gdb) info register ecx
ecx            0x804a010        134520848
(gdb) x 0x804a010
0x804a010 <msg>:        0x61707070
(gdb) x 0x804a014
0x804a014:      0x00006161

显然，"70"代表字符"p"，"61"代表字符"a".

"70" here represents the character 'p' and "61" the character 'a' obviously.

我感到困惑的是，为什么位置0x804a010中的数据为0x61707070(appp)，并在0x804a014处向前移动4个字节，数据为--aa?

What I am confused about is, why is the data in location 0x804a010 is 0x61707070 (appp) and moving 4 bytes forward at 0x804a014 the data is --aa ?

我希望第一个位置看到(pppa)，第二个位置看到(aa--).为什么会这样?

I would expect to see (pppa) for the first location and (aa--) for the second location. Why is this the case?

推荐答案

GDB不知道您有一堆字符.您只是要求它查看一个内存位置，并显示那里的内容，默认为4字节整数.它假定该整数首先存储了最低有效字节，因为这是在Intel上完成的，因此您的字节反转了.

GDB doesn't know that you have a bunch of chars. You are just asking it to look at a memory location and it is displaying what is there, defaulting to a 4-byte integer. It assumes the integer is stored least significant byte first, because that is how it is done on Intel, so you get your bytes reversed.

要解决此问题，请在您的 x 命令中使用格式说明符，如下所示:

To fix this, use a format specifier with your x command, like this:

 x/10c 0x804a010 

(将从0x804a010开始打印10个字符).

(will print 10 chars beginning at 0x804a010).

help x 将提供更多信息.

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