如何调用x86汇编与fgets？ [英] How to call fgets in x86 assembly?

问题描述

根据为与fgets的文档（） ，函数有三个参数：

According to the documentation for fgets(), the function takes three parameters:

• 的char * - 将一直保持输入的字符串


• INT - 这重新presents的最大字符数的整数读


• FILE * - 一个 FILE * 到流从读

• char * - a string that will hold the input
• int - an integer that represents the maximum number of characters to read
• FILE * - a FILE * to the stream to read from

我有麻烦调用该函数。我只是推三个参数压入堆栈，调用函数，并增加 ESP 12

I have no trouble calling the function. I just push the three parameters onto the stack, call the function, and increase ESP by 12.

我的问题是与参数＃3。什么应该被传递作为 FILE * 标准输入？在C中，我可以只使用标准输入，但我不知道是相当于在x86汇编的东西。

My problem is with parameter #3. What should be passed in as the FILE * for standard input? In C, I can just use stdin, but I don't know what the equivalent is in x86 assembly.

更新：我在Linux上使用NASM

Update: I'm using NASM on Linux.

推荐答案

与标准输入的问题是，它是一个可扩展的东西不仅是特定于平台的宏，但最有可能难以从装配手工访问。如果你愿意牺牲 STDIO 和使用POSIX调用代替，标准输入是一样的知名文件描述符＃0。因此，您可以通过 0 来 读 并得到几乎是你所期待的。我是pretty知道这是更加汇编友好比标准输入 C代码宏。

The problem with stdin is that it's a macro that expands to something not only platform-specific, but most likely difficult to access from assembly by hand. If you're willing to sacrifice stdio and use POSIX calls instead, stdin is the same as the well-known file descriptor #0. You can therefore pass 0 to read and get almost what you were looking for. I'm pretty sure this is more assembler-friendly than the stdin C macro.

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