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wishmaster

Joined: 25 Aug 2004
Posts: 9

wishmaster 09 Oct 2004, 12:50

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.

09 Oct 2004, 12:50

crc

Joined: 21 Jun 2003
Posts: 637
Location: Penndel, PA [USA]

crc 09 Oct 2004, 13:04

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.

09 Oct 2004, 13:04

wishmaster

Joined: 25 Aug 2004
Posts: 9

wishmaster 09 Oct 2004, 13:14

Is there a way to check the value of a variable ? TASM supports that.

09 Oct 2004, 13:14

Matrix

Joined: 04 Sep 2004
Posts: 1166
Location: Overflow

Matrix 09 Oct 2004, 13:34

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 
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

09 Oct 2004, 13:34

crc

Joined: 21 Jun 2003
Posts: 637
Location: Penndel, PA [USA]

crc 09 Oct 2004, 13:50

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?

09 Oct 2004, 13:50

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8353
Location: Kraków, Poland

Tomasz Grysztar 09 Oct 2004, 20:29

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.

09 Oct 2004, 20:29

wishmaster

Joined: 25 Aug 2004
Posts: 9

wishmaster 10 Oct 2004, 11:03

Thank you, that works well Very Happy

10 Oct 2004, 11:03

Dragontamer

Joined: 24 Aug 2003
Posts: 84

Dragontamer 10 Oct 2004, 23:59

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.

10 Oct 2004, 23:59

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