Compile Assembly code that includes header files containing C-definitions

Question

I'm trying to compile assembly and C code together (not C to assembly), but can't get it done.

For example:

file common.h

#ifndef __COMMON_H__
#define __COMMON_H__

struct tree{
        tree* left;
        tree* right;

        void* elem;
};

void foo(int c);
#endif

file common.S

#include "common.h"

    .text
    .globl foo
    .ent foo
foo:
     //foo implementation

    .end foo

When I try to compile this:

# gcc -c common.S
common.h: Assembler messages:
common.h:5: Error: unrecognized opcode `struct tree{'
common.h:7: Error: unrecognized opcode `tree* left'
common.h:8: Error: unrecognized opcode `tree* right'
common.h:10: Error: unrecognized opcode `void* elem'
common.h:12: Error: junk at end of line, first unrecognized character is `}'
common.h:14: Error: unrecognized opcode `void foo(int c)'

Is there any way to take C-definitions into assembly using gcc?

Answer 1

No, you can't include C declarations in assembly language. The assembler has no idea what struct tree means.

If you want to write an assembly language function foo that makes use of your definition of struct tree, you're going to have to do it without making use of the C header file.

To get an idea of what this might look like, write the foo function in C, compile it with gcc -S to generate an assembly listing, and then take a look at the resulting compiler-generated common.s file. (You should probably do this in a separate directory so you don't clobber your existing common.s file.)

You probably won't see any references to struct tree or to the member names left, right, and elem; instead, you'll see assembly opcodes that refer to data at certain offsets.