Understanding how NASM macros(?) work

[scmaccal]

Greetings,

I would like to see how: times 510-($-$$) db 0 and db works from a assembly language point of view. Is there an option that I can add that will produce the assembly code of these NASM macros(?) when I assemble a program? I just tried the -l option but that was not helpful.

[Frank Kotler]

It's just a bunch of zeros - sufficient to pad your bootsector (?) out to 510 bytes. (bytes 511 and 512 are the boot signature) Ndisasm would show them... but would try to disassemble them. A hex dump would show them. Not much to see...

Best,
Frank

[scmaccal]

Frank,

Thank you for replying. I did in fact do a disassemble of the binary in question. You are correct, a bunch of zeros. So my question now is how would I go about writing the code that does the same as:

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times 510-($-$$) db 0 by hand. I suspect you may see a theme with this post and the other one that you were kind enough to answer. I want to use as much Intel syntax as possible in my programs. I am doing this because I want to develop a deeper knowledge of how to program in assembly language without relying on the assembler to do the work for me. If I wanted that I would write in C.

Kind regards,

Scott

[Frank Kotler]

Hi Scott,

Well, literally:

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db 0
db 0
db 0
db 0
; enough times
but you could do:

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db 0, 0, 0, 0, 0 ; enough times
with the same result.

When I can get both remaining brain cells to fire at the same time, I can do things Nasm can't do. Counting bytes isn't one of them. Nasm can count bytes faster and more accurately than I can. If you've got more brain cells than you know what to do with, you can count 'em yourself of course. I've gotta save my strength!

Best,
Frank