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Kroustibat
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Stupid Z80 assembly question
 Posted: Thu Apr 13, 2000 6:10 am
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Hi there,
I've start learning emu programming (a sega of course) , i use Mz80 3.4
I've let mz80 manage all the memory access (so my memory map structure is empty) i don't know if it's a good way
(i know that if there's a write to the rom..)
After launching the emu, the code seems to goes into a infinite loop, so i've dissasemble the rom but i'm not an assembly freak
here's what i get
the memory region c00b seems to be at 0x00
and the inifinte loop
03d9 3a0bc0 ld a,(#c00b)
03dc b7 or a
03dd 28fa jr z,#03d9
with what bit mask the "OR" operand works ?
Tia
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- Joined: 24 Jun 1999
- Posts: 1732
- Location: Paris, France
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Posted: Thu Apr 13, 2000 8:29 am
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Quote > and the inifinte loop
> 03d9 3a0bc0 ld a,(#c00b)
> 03dc b7 or a
> 03dd 28fa jr z,#03d9
> with what bit mask the "OR" operand works ?
OR works with A. So in this case it's OR A, A
A quick way to test if A is null or not.
Basically the loop wait for A to be not null.
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Kroustibat
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Posted: Thu Apr 13, 2000 10:23 am
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Quote > OR works with A. So in this case it's OR A, A
> A quick way to test if A is null or not.
> Basically the loop wait for A to be not null.
Thanks for your quick response !! :)
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