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 dd eax not working 
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Joined: Thu Dec 23, 2010 1:12 pm
Posts: 9
Post dd eax not working
When I try to write the value of eax to ram using
Code:
dd eax
nasm gives me an error message saying:
Code:
error: operand 1: expression is not simple or relocatable
I don't see how I'm doing it wrong because the code looks fine to me.


Wed Mar 23, 2011 4:36 pm
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Joined: Fri Aug 20, 2010 10:04 pm
Posts: 41
Post Re: dd eax not working
"dd" is "define double". Puts a constant in a spot. It is not an instruction.

You want to use the "mov" instruction.

Code:
    mov [01000h],eax


Something like that. You better start with a book on asm, honestly.


Thu Mar 24, 2011 1:38 am
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Joined: Thu Dec 23, 2010 1:12 pm
Posts: 9
Post Re: dd eax not working
So
Code:
example: resd 1
mov [example], eax
should work? I'll try it.


Thu Mar 24, 2011 10:13 am
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Joined: Fri Jul 24, 2009 10:02 pm
Posts: 247
Location: Las Vegas, NV, US
Post Re: dd eax not working
Yep, losethos is right, you need to use the `mov` command and they way you are using it now should move the value in `eax` and move it intomemory at the address labeled `example`. But what is the `resd` opcode? I've never seen that and can't find any reference to it in the intel x86 opcode list.


Tue Aug 23, 2011 1:14 am
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Joined: Thu Dec 23, 2010 1:12 pm
Posts: 9
Post Re: dd eax not working
Resd reserves a double word(the 1 means only reserve one) but I have now found out that it can only be used in the bss section. I understand now that DD actually puts the value in that place in the executable which ends up in ram.


Wed Aug 31, 2011 4:12 pm
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