Question about declaring variables

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inhahe

Joined: 18 Jul 2008
Posts: 2
Location: miami.fl.usa

inhahe 18 Jul 2008, 02:56

How do I declare variables that have a place in memory but don't take up any bytes in the output file? I mean it seems a shame to use up extra bytes in the file for variables that don't need an initial value. (I'm kinda new to assembly.)

18 Jul 2008, 02:56

comrade

Joined: 16 Jun 2003
Posts: 1140
Location: Russian Federation

comrade 18 Jul 2008, 03:20

See http://flatassembler.net/docs.php?article=manual#1.2.2

Basically, use either the "db ?" syntax, or the "rb" syntax.

18 Jul 2008, 03:20

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 18 Jul 2008, 03:23

Just by defining them with the value "?" (for example: aByte db ?).

Note however that the uninitialized variables must be placed AFTER any initialized data or instructions, otherwise the "?"'s will be filled with zeroes (and will take up space).

Example:

Code:

org $100
jmp exit
aByte db ?
exit: int $20

Makes a 5 bytes file while

Code:

org $100
jmp exit
exit: int $20
aByte db ?

Makes a 4 bytes file.

18 Jul 2008, 03:23

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