How to break down a NASM application into modules/packages and include them?

Question

I'm starting to learn the Assembly language. I'm familiar with it in the basic level. I wonder, how big application in the Assembly are organized, that is, how can I split them into modules/packages and include them into other modules? I'm talking about NASM in particular.

Answer 1

You can either:

• Use %include
  To include an external file into the current one.
  This can be further controlled with the -i command line switch.

  You can also force NASM to pre-include a file using the -p switch.

• Assemble multiple files
  Since NASM is not a linker, you can take advantage of the linkers' ability to... well, link files together.

  Use the GLOBAL directive to make a set of symbols visible to other modules.
  Use the EXTERN directive to import a set of symbols from other modules.

  You can pass all the object files to the linker.
  NASM (as today) can only assemble one file at a time, so a build script is needed.

---

The two above are not mutually exclusive but you have to basically understand the NASM output file formats to see when the latter is applicable.