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Index > Main > Stop fasm complaining about operand sizes?

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AzraelUK



Joined: 23 Nov 2008
Posts: 3
AzraelUK
Is there a way to stop fasm giving the error 'operand sizes do not match.'? I've got 32 reserved bytes with an ASCII string, and to do comparing I figure the fastest way to do it is 4 bytes at a time. However, because the string is defined with rb, if I try 'mov eax, [user+ecx]' then it will give the operand size error because it doesn't understand that I want to load four bytes of data into eax, rather than just the one.

Is there any way to coerce the assembler into letting me do this? Reserving the bytes with rd isn't an option, because I need to play with the individual bytes of the string in other parts of the code.

The only solution I can think of is loading each byte into al and then doing a shl 8, but that's so tedious I may as well just give up and write my program in C. Wink
Post 24 Nov 2008, 18:20
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baldr



Joined: 19 Mar 2008
Posts: 1651
baldr
AzraelUK, use label directive or override type with dword operator.


Last edited by baldr on 24 Nov 2008, 18:36; edited 1 time in total
Post 24 Nov 2008, 18:34
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17343
Location: In your JS exploiting you and your system
revolution
Or just use the dword override:
Code:
mov eax,dword[user+ecx]    
Post 24 Nov 2008, 18:36
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baldr



Joined: 19 Mar 2008
Posts: 1651
baldr
revolution,

I thought about two labels to the same address and edited post… And you was first, Mr. Hyde! Wink
Post 24 Nov 2008, 18:39
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17343
Location: In your JS exploiting you and your system
revolution
baldr: Too slow Dr. Jekyll.
Post 24 Nov 2008, 18:41
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wht36



Joined: 18 Sep 2005
Posts: 106
wht36
The easiest is just put a colon after your label.
So instead of
Code:
a_string rb 32    

use
Code:
a_string: rb 32    
Post 26 Dec 2008, 06:52
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