混合C和汇编文件 [英] Mixing C and Assembly files

问题描述

我想用一个裸体功能< /采用G ++一>在我的C ++程序。不幸的是G ++，不像VC ++，不支持裸职能和管理，这是写自己组装code在一个单独的文件连接你的C ++文件的唯一途径。我试图找到一些很好的教程用于x86混合汇编和C / C ++文件，但找不到任何好的。

I want to use a naked function in my C++ program using g++. Unfortunately g++, unlike VC++, does not support naked functions and the only way to manage this is to write your own assembly code in a separate file and link with your C++ files. I tried to find some good tutorial for x86 to mix assembly and C/C++ files but couldn't find any good one.

请让我知道如果你知道任何。请注意，我不是问内嵌汇编，但联用的Makefile C和汇编文件，以及如何申报装配，反之亦然的C extern变量除了在C语言或汇编使用它们，并且还的方式到C链接和ASM文件

Kindly let me know if you know about any. Note that I'm not asking about inline assembly but linking C and assembly files and ways to declare extern variables of C in assembly and vice versa besides using them in either C or assembly, and also ways to link the C and asm files using Makefile.

推荐答案

在C ++文件：

extern "C" void foo(); // Stop name mangling games

int main() {
  foo();
}

在裸体ASM文件，86：

in "naked" asm file, for x86:

# modified from http://asm.sourceforge.net/howto/hello.html

.text                   # section declaration
    .global foo

foo:

# write our string to stdout

    movl    $len,%edx   # third argument: message length
    movl    $msg,%ecx   # second argument: pointer to message to write
    movl    $1,%ebx     # first argument: file handle (stdout)
    movl    $4,%eax     # system call number (sys_write)
    int $0x80       # call kernel

# and exit

    movl    $0,%ebx     # first argument: exit code
    movl    $1,%eax     # system call number (sys_exit)
    int $0x80       # call kernel

.data                   # section declaration

msg:
    .ascii  "Hello, world!\n"   # our dear string
    len = . - msg           # length of our dear string

编译，汇编和链接（使用g ++而不是ld，因为它是很容易做的这种方式对于C ++），然后运行：

Compile, assemble and link (with g++ rather than ld because it's much easier to do it that way for C++) and run:

ajw@rapunzel:/tmp > g++ -Wall -Wextra test.cc -c -o test.o
ajw@rapunzel:/tmp > as -o asm.o asm.S
ajw@rapunzel:/tmp > g++ test.o asm.o
ajw@rapunzel:/tmp > ./a.out
Hello, world!

显然，如果你想将参数传递给你的函数或者返回任何你需要尊重的调用约定。

Clearly if you want to pass arguments to your function or return anything you need to respect the calling conventions.

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