I would like to split my nasm code into several files, so that I can work on different pieces of code separately. However, the only way I found is using nasm %include macro. For example. main.asm file looks somewhat like this,
; ---- main.asm ----
%include "./header.asm"
section .text
global _start
_start:
call dummy_func
mov rax, 0x3c
mov rdx, 0x0
syscall
while header.asm only contains
section .text
dummy_func:
ret
I have heard about a way to do this during linking. I got very interested in that, but couldn't find anything appropriate. Is it really possible? If so, can it be done with ld? What other means are there to include a static library? (probably some more macros. However I'm not sure "macros" is the right word here)
No need for static libraries - you can declare the function as external. In your case, main.asm would look like:
; ---- main.asm ----
section .text
global _start
extern dummy_func
_start:
call dummy_func
mov rax, 0x3c
mov rdx, 0x0
syscall
Then compile your source files to object files:
nasm main.asm -o main.o
nasm header.asm -o header.o
Then you can finally use ld to link the 2 object files into a single executable:
ld -o [desired executable name] main.o header.o
The extern keyword basically means the function dummy_func is located in a different object file, and that the object file containing dummy_func MUST be linked into the executable at the end. This is a much better way of doing things than using %include.