gnu汇编中.byte汇编程序指令的用途是什么? [英] What is the use of .byte assembler directive in gnu assembly?

问题描述

在进行一些带有内联汇编的C代码时，我遇到了.byte(以Dot开头)指令.

While going through some C code having inline assembly I came across the .byte (with a Dot at the beginning) directive.

在检查Web上的程序集引用时，我发现它用于在内存中保留一个字节.

On checking the assembly reference on web I found that it is used to reserve a byte in memory.

但是在代码中，语句前没有标签.因此，我想知道无标签的.byte指令或任何其他数据存储指令在此用途是什么.

But in the code there was no label before the statement. So I was wondering what is use of an unlabeled .byte directive or any other data storage directive for that matter.

例如如果我对.byte 0x0a进行编码，该如何使用?

For e.g. if i code .byte 0x0a, how can i use it ?

推荐答案

有几种可能...我想到的有几个:

There are a few possibilities... here are a couple I can think of off the top of my head:

1. 您可以相对于.byte指令后 的标签来访问它.示例:

1. You could access it relative to a label that comes after the .byte directive. Example:

  .byte 0x0a
label:
  mov (label - 1), %eax

基于程序的最终链接布局，也许.byte指令将作为代码执行.通常，在这种情况下，您也会有一个标签，但是...

Based on the final linked layout of the program, maybe the .byte directives will get executed as code. Normally you'd have a label in this case too, though...

某些汇编程序不支持为操作数大小等生成x86指令前缀.在为那些汇编程序编写的代码中，您经常会看到类似这样的内容:

Some assemblers don't support generating x86 instruction prefixes for operand size, etc. In code written for those assemblers, you'll often see something like:

  .byte 0x66
  mov $12, %eax

要使汇编器发出您想要的代码.

To make the assembler emit the code you want to have.

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