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Index > Windows > invoke [local variable] compile error

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mindcooler



Joined: 01 Dec 2009
Posts: 423
Location: Västerås, Sweden
mindcooler
What am I doing wrong here? (win32wxp.inc)

Code:
proc main
 locals
  ...
  hfile           rd 1
  ... 
 endl      


Code:
mov     [hfile],eax

invoke  GetFileSize,[hfile],filesizeh ;<-- Error: invalid value (push ..var?QU)    


Worked when it was global.

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Post 12 Apr 2010, 21:38
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
Is "filesizeh" also local? In that case use "addr filesizeh" instead.

[edit]This works:
Code:
include 'win32axp.inc'

proc main
 locals
  hfile           rd 1
  filesizeh       rd 1
 endl

 invoke GetFileSize, [hfile], addr filesizeh
 ret
endp

.end main    
[/edit]
Post 12 Apr 2010, 21:54
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mindcooler



Joined: 01 Dec 2009
Posts: 423
Location: Västerås, Sweden
mindcooler
Yes, that makes it work. Remind me, why is addr needed here? Now that you mention it I have seen similar threads around here. Is it needed to explicitly produce lea instructions?
Post 12 Apr 2010, 23:46
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
Because if you don't use addr you'll get "push ebp+offset", and the processor does not support that. With global vars this problem does not occur because the address ends up being a single number so the "push imm32" instruction can be used there.

And yes, "addr" (which use "lea edx, [argument] / push edx") has to be explicitly specified (and you also have to be aware that EDX is obviously destroyed in the process so you have to be careful if you use it as an argument).
Post 13 Apr 2010, 00:24
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bitshifter



Joined: 04 Dec 2007
Posts: 764
Location: Massachusetts, USA
bitshifter
In short: Local variables are stored on the local stack frame.
Post 13 Apr 2010, 03:07
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mindcooler



Joined: 01 Dec 2009
Posts: 423
Location: Västerås, Sweden
mindcooler
OK, thanks, I can buy that I need to make it explicit because I need to be aware of that edx gets clobbered. The error message was a bit hard to interpret Smile
Post 13 Apr 2010, 08:26
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