AT＆amp; T公司大会蒙面输入 [英] AT&T Assembly Masked Input

问题描述

我试图创造AT＆放一个简单的密码程序​​，变速箱总成，但我有掩蔽输入的麻烦。我希望发生的是，当用户输入字符，它们出现在屏幕上的星号。英特尔的语法是比较简单的：

I'm trying to create a simple password program in AT&T Assembly but i'm having trouble with masking an input. What i want to happen is when the user enters characters, they appear on the screen as asterisk'. In intel syntax it's relatively simple:

mov ah, 08h
int 21h

mov dl,2ah
mov ah,02h
int 21h

本使用英特尔命令来读取输入而不呼应它，而是打印一个星号。
我试图解决AT＆放这个问题; T语法，我遇到了一些麻烦。

This uses the intel command to read an input without echoing it and instead print an asterisk. I'm trying to solve this problem in AT&T syntax and I'm having some trouble.

任何投入将大大AP preciated。
先谢谢了。

Any input would be greatly appreciated. Thanks in advance.

推荐答案

请纠正我，如果我错了：

在AT＆amp; T公司装配十六进制写C语言风格：的0x30 而不是 30小时的。八进制也类似于C $ P $与pfixed一个 0 。

In AT&T assembly hexadecimal is written C-style: 0x30 instead of 30h. Octals are also like in C, prefixed with a 0.

和具体取决于大小的内存你操纵你必须使用这种规模的后缀操作数。这意味着 MOVL 而不是 MOV 在32位长记忆：

And depending on what size memory you are manipulating you have to use that size's postfix on the operand. That means movl instead of mov on 32bit long memory:

8 bits = b      - derived from "byte"
16 bits = w     - derived from "word"
32 bits = l     - I have no idea why 16 bits is usually a "dword"
64 bits = q     - derived from "qword", q for "quad-", so four words in size

另外的值是美元符号pfixed $ P $ $×41 （因为是变量？）和寄存器是$ P $与百分号pfixed：％EAX 。

Also values are prefixed with a dollar sign: $0x41 (as are variables?) and registers are prefixed with percent signs: %eax.

所以，如果我读这正确的code应该是：

So if I'm reading this correctly your code should be:

movl $ah, $0x08
int 0x21

movl $dl, $2ah
movl $ah, $0x02
int $0x21

我无法相信我错过了这个时候，我写了答案，AT＆安培; T语法颠倒了源 - 目的为了说明它有两个输入

I can't believe I missed this when I wrote the answer, AT&T syntax has reversed source-destination order for instructions with two inputs.

即。 AT＆amp; T公司是：

I.e. AT&T is:

movl <source>, <dest>

而在英特尔的语法，这将是：

while in Intel syntax this will be:

mov <dest>, <source>

任何更正，欢迎，因为我还在学习为好。

Any corrections are welcome as I'm still learning as well.

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