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Index > Main > why getting virtual address works on lea but fail on mov?

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vbVeryBeginner



Joined: 15 Aug 2004
Posts: 884
Location: \\world\asia\malaysia
vbVeryBeginner
struct fruit
price dd ?
local db ?
ends

virtual at edx
.banana fruit
end virtual

lea edx,[.banana.price] ;<- ok
mov edx,.banana.price ;<- failed

any idea?
Post 17 Mar 2006, 14:04
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Tomasz Grysztar



Joined: 16 Jun 2003
Posts: 7802
Location: Kraków, Poland
Tomasz Grysztar
SIB addresses cannot be used like register operand, sorry.
Note that in most cases it would anyway make no sense as it would be "mov edx,edx+some_offset". fasm doesn't bother checking whether the offset it zero (and whether there is no index register, too) to detect the rare case when it could get reduced to be only the register, thus this is like a fasm's limitation. I don't consider it to be very limiting, though.
PS. This limitation also applies to the cases when you write "mov edx,2+edx-2" etc. It's because "2+edx+2" is an expression and simple "edx" is an register - something different from the parsed source point of view (see how the "eqtype" works).
Post 17 Mar 2006, 15:33
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vbVeryBeginner



Joined: 15 Aug 2004
Posts: 884
Location: \\world\asia\malaysia
vbVeryBeginner
thank you
Post 18 Mar 2006, 14:31
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