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Index > Main > Jump Above or Equal, or Jump Carry Clear.

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SoLo2



Joined: 09 Mar 2007
Posts: 14
SoLo2
I am using 1 Byte in AL to
count from 244 to 0 included.
This means that I have to check
for zero or above to repeat
the loop, or carry clear, as I
think that carry would happen
when turning from 0 to -1 (255),
right?


Well... I tried a little routine like
this in fasm, but it never ends:

mov al,244
loop0:
call ClearFMRegister
dec al
jcc loop0

FYI, this is supposed to clear
registers of the FM synth of
soundblaster/adlib cards
(which I don't manage too sound)

Greetings,
so_o2
Post 26 Aug 2007, 05:32
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ManOfSteel



Joined: 02 Feb 2005
Posts: 1154
ManOfSteel
1. carry jump is 'jc' or 'jnc' not 'jcc'.
2. dec doesn't change the carry flag. You should use 'sub reg,1' for that.
3. if you want to use 'dec' use 'jnz'. And don't forget to save 'eax' in 'ClearFMRegister'. Also, keep in mind that j(n)z will jump on zero (0) condition while j(n)c will jump on carry condition (255 / -1), so there's a difference of 1 between the two.
Post 26 Aug 2007, 06:19
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SoLo2



Joined: 09 Mar 2007
Posts: 14
SoLo2
Thanks ManOfSteel!

I will be using "sub reg,1" then.
And, of course, it was "jnc" and not "jcc".

Greetings,
SoLo2
Post 26 Aug 2007, 07:05
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