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Z80 & 68k Assembly =>
z80 & ez80 Assembly
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Tyraniek
Member
Joined: 07 Jun 2003
Posts: 133
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 Posted: 07 Jun 2003 12:45:24 pm Post subject: |
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It is a stupid question, but how do you do to add A to B ?
You can't write "add B, A", but you can write "add A, B". So you'd certainly exchange A and B, but can't either !!!!!!!!!!! 
So what could I write ??????? It is though something quite basic, isn't it ?
For exemple, how would you write this following BASIC program in ASM ???
Code:
For(F, 47, 0, -1)
Line(47+F, 0, 47+F, 62)
Line(47-F, 0, 47-F, 62)
End
I changed 47+F in
Code:
ld b, 47
add b, a; with "A" decremented in a loop
Do you have the solution to this problem ? o_O
thank you
Last edited by Guest on 07 Jun 2003 12:46:43 pm; edited 1 time in total |
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Adm.Wiggin
aka Tianon
Know-It-All
Joined: 02 Jun 2003
Posts: 1874
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| Posted: 07 Jun 2003 01:25:02 pm Post subject: |
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i would try this :
push af
ld b,47
add a,b
ld b,a
pop af
would that work for ur problem? just a thought... |
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Justin W.
Shattered Silence
Advanced Member
Joined: 24 May 2003
Posts: 429
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| Posted: 07 Jun 2003 05:42:19 pm Post subject: |
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Well so long as you don't need the accumulator for anything you could just.
ld b,47
add a,b
ld b,a
If you need the accumulator then use Adm. Wiggin's code. |
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Adm.Wiggin
aka Tianon
Know-It-All
Joined: 02 Jun 2003
Posts: 1874
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| Posted: 07 Jun 2003 08:20:56 pm Post subject: |
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| from what i gather, he needs to keep a intact for the loop... if a were to die, then the loop would be messed up too... |
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NETWizz
Byte by bit
Bandwidth Hog
Joined: 20 May 2003
Posts: 2369
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| Posted: 08 Jun 2003 02:43:15 am Post subject: |
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Maybe he would be interested in the djnz loop.
e.g.
ld b,8
loop
;do stuff 8 times
djnz loop |
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Tyraniek
Member
Joined: 07 Jun 2003
Posts: 133
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| Posted: 08 Jun 2003 08:35:38 am Post subject: |
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Thank you, I may use it one day, but for the moment, I've found another way.
Remember, I wanted to use that to do the equivalent of
Code:
For(F, 47, 0, -1)
Line(47+F, 0, 47+F, 62)
Line(47-F, 0, 47-F, 62)
End
The "F" of the For is "a", and the coordonates are b, c, d, e (h=0 : OFF, h=1 : ON)
But finally I used the equivalent of :
Code:
For(F, 47, 0, -1)
Vertical 47+F
Vertical 47-F
End
with OP1 for the abscisse of Vertical !
So thank you, but I will keep my way  (how to do then, if we can't change registers a, b, c, d, e, h)
thx
Last edited by Guest on 08 Jun 2003 02:46:04 pm; edited 1 time in total |
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