How to call a function in an external assembly file [duplicate]

问题

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calling assembly function from c (4 answers)

Calling an assembly function from C (2 answers)

Passing parameters from C to GNU Assembly function in 64bit (1 answer)

Closed 6 days ago.

I am trying to go from a C function to a function with inline-asm to a standalone function in an assembly file. Here is what I have so far:

#include <stdio.h>

int add_five(int n)
{
    n = n + 5;
    return n;
}

int add_five_inline(int n)
{
    asm("lea 5(%1), %0" : "=r" (n) : "r" (n));
    return n;
}

int main(void)
{
    int a=add_five(7);
    int b=add_five_inline(8);
    // int c=add_five_asm(9); // <-- here
    printf("7+5=%d | 8+5=%d\n", a, b);

}

7+5=12 | 8+5=13

What is the process to take something like the following asm and call it from a C function?

# file.s
add_five_asm:
    lea 5(%rdi), %rax
    ret

How would I call and compile so that I can call that asm function 'as-if' it were a normal C function?

来源：https://stackoverflow.com/questions/65837016/how-to-call-a-function-in-an-external-assembly-file