CODEWITHSUNDEEP
gccc-preprocessor
th3falc0n
th3falc0n

Reputation: 1427

How do I enable the preprocessor in gcc assembly

I am using the GCC like this:

gcc -std=gnu99 -fno-leading-underscore -m32 -c -o obj/entry.o src/entry.s

However, when I compile the linker says:

ld -melf_i386 -T kernel.ld -o kernel obj/entry.o obj/init.o
obj/entry.o:(multiboot+0x0): undefined reference to `MB_MAGIC'
obj/entry.o:(multiboot+0x4): undefined reference to `MB_FLAGS'
obj/entry.o:(multiboot+0x8): undefined reference to `MB_CHECKSUM'

Those references are defined in the entry.s file with the preprocessor:

#define MB_MAGIC 0x1badb002
#define MB_FLAGS 0x0
#define MB_CHECKSUM -(MB_MAGIC + MB_FLAGS)

How can I enable preprocessing?

Upvotes: 4

Views: 4712

Answers (1)

Marc Glisse
Marc Glisse

Reputation: 7915

As explained in gcc's documentation, if the file name ends in capital .S, it will be preprocessed automatically. You can add the -v option to see what steps gcc follows. If you don't want to change the file name, you can also specify the language with -x assembler-with-cpp (before the file name).

Upvotes: 9

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