assemblymacrosidentifiergnu-assembler

GNU Assembler identifier concatenation inside macro

I want to append a string to a macro argument in gcc assembler. Here is what I have currently:

The following macro to embed a file in my code which works just fine:

.macro add_resource resource_name, file_name
    .global \resource_name
    .type \resource_name, @object
    .balign 4
\resource_name:
    .incbin "\file_name"
end_\resource_name:
    .global size_\resource_name
    .type size_\resource_name, @object
    .balign 4
size_\resource_name:
    .int end_\resource_name - \resource_name
.endm

.section .rodata

add_resource icon, "icon.png"

usage:

#include <stdio.h>
extern unsigned char icon[];
extern unsigned int size_icon;
int main() {
    printf("magic bytes: %.3s, size: %u", icon+1, size_icon);
    return 0;
}

running nm on produced executable:

0000000000f99b9d r end_icon
0000000000002020 R icon
0000000000f99ba0 R size_icon

the program prints "magic bytes: PNG, size: 16350077".

But the name "size_icon" looks awful, and i want to append the "size", instead of prepending it, which would make it "icon_size". But i don't know how to do that and couldn't find anything useful in documentation. Can anyone help?

Solution

  • As Jester pointed out, I overlooked the \() syntax. I can just write \resource_name\()_size and it will generate "image_size" identifier.