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wishmaster



Joined: 25 Aug 2004
Posts: 9
wishmaster
Hi, i have a problem with "if". I want to use if on a value from a variable:

Code:
abc db 5
.....
if [abc] > 6
end if
......
    


But that doesnt work: error: invalid value.

I hope somebody can help me.
Post 09 Oct 2004, 12:50
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crc



Joined: 21 Jun 2003
Posts: 637
Location: Penndel, PA [USA]
crc
IF is processed before the assembly takes place. I don't think that you can check the value of a variable at the preprocessing stage.
Post 09 Oct 2004, 13:04
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wishmaster



Joined: 25 Aug 2004
Posts: 9
wishmaster
Is there a way to check the value of a variable ? TASM supports that.
Post 09 Oct 2004, 13:14
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Matrix



Joined: 04 Sep 2004
Posts: 1171
Location: Overflow
Matrix
Smile
don't use post processor for that

Code:
; you can say this is a character table writer program,
; but its destination is to demonstrate using a simple variable in FASM
; MATRIX
; oh, i have discovered it is 32 bytes Smile
org 256

and word [testvar],0
mov ax,$b800
push es
mov es,ax

mov ah,$07
mainloop:
stosw
inc word [testvar]
mov al,byte [testvar]
cmp word [testvar],255
jb mainloop ; if [testvar] <= 50 then goto mainloop

pop es
int 20h

testvar: rw 1
    


MATRIX
Post 09 Oct 2004, 13:34
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crc



Joined: 21 Jun 2003
Posts: 637
Location: Penndel, PA [USA]
crc
I think you could do something like:

Code:
abc_value = 5
abc db abc_value

if abc_value < 6
. . .
then
    


Just out of curiosity, why do you need to check the value of a variable during the preprocessing time?
Post 09 Oct 2004, 13:50
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Tomasz Grysztar



Joined: 16 Jun 2003
Posts: 7756
Location: Kraków, Poland
Tomasz Grysztar
crc: what you've done it's better to do this way:
Code:
abc db 5

load abc_value from abc
if abc_value < 6
; ...
end if    


However it seems that it's just the ".if" macro what wishmaster is looking for, to generate the code that will do the checking of the variable at the run time.
Post 09 Oct 2004, 20:29
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wishmaster



Joined: 25 Aug 2004
Posts: 9
wishmaster
Thank you, that works well Very Happy
Post 10 Oct 2004, 11:03
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Dragontamer



Joined: 24 Aug 2003
Posts: 84
Dragontamer
Just wanna make sure you know...

the if statement will always be true.

It is a PREPROCESSOR statement. I agree with Privalov, the ".if" macro is what you want.

What I would use, is the conditional jumps. But thats just me.
Post 10 Oct 2004, 23:59
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