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flat assembler > Programming Language Design > align directive

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HopekForth



Joined: 13 Jul 2017
Posts: 1
Location: Poland
Good morning, everyone.

In his flat assembler 1.71 Programmer's Manual Tomek wrote about align directive:

Quote:
The align directive fills the bytes that had to be skipped to perform the alignment with the nop instructions


and later:

Quote:
If you need to fill the alignment area with some other values, you can combine align with virtual to get the size of alignment needed and then create the alignment yourself, like:

virtual
align 16
a = $ - $$
end virtual
db a dup 0

Today I found that the same can be done shorter:

db (- $) and $F dup 0

and you needn't know what virtual or $$ is Smile

You all can freely use my idea in your works.
Post 13 Jul 2017, 08:43
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Tomasz Grysztar
Assembly Artist


Joined: 16 Jun 2003
Posts: 6981
Location: Kraków, Poland
Keep in mind that this only works if $ has an absolute value (a known number), and this is not true in case of relocatable formats, like object files (COFF/ELF) or PE executables with fixups - for this reason internally implemented ALIGN directive was needed.
Post 13 Jul 2017, 10:10
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