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gnomen



Joined: 07 Oct 2003
Posts: 13
gnomen
I am trying to make a simple procedure for showing an error MessageBox, but it's wierd... look at this:
Code:
; in .data:
; _error db 'Error!',0
proc error, AText
    enter
        mov     eax, [AText]
        invoke  MsgBox,HWND_DESKTOP,eax,_error,MB_OK+MB_ICONERROR
        return      
    

And when I try to invoke it:
Code:
; in .data:
; _writefile db 'WriteFile error!',0
invoke  error,_writefile
    

I get the compiler message 'operand size not specified'?

OOPS Embarassed : Replacing invoke with stdcall made it work perfectly:
Code:
; in .data:
; _writefile db 'WriteFile error!',0
stdcall  error,_writefile
    
Post 14 Oct 2003, 15:06
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MattBro



Joined: 08 Nov 2003
Posts: 37
MattBro
Looks familiar

I made the same mistake when I first started using this.
More than once in fact. When I look at the actual macro definition for invoke,

macro invoke proc,[arg] ; invoke procedure (indirect)
{ common
if ~ arg eq
stdcall [proc],arg
else
call [proc]
end if }


it seems that invoke uses the proc argument as a pointer to the procedure name, so it is an indirect call, whereas I suppose the proc call should be 'direct'.

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Post 21 Nov 2003, 05:30
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eet_1024



Joined: 22 Jul 2003
Posts: 59
eet_1024
stdcall is used for calls to proc's in your code.

invoke is used to call functions that are imported from a DLL, such as kernel32.dll, user32.dll, or your own dll.

btw, you can push the contents of a stack frame:
invoke MsgBox,HWND_DESKTOP,[AText],_error,MB_OK+MB_ICONERROR
Post 21 Nov 2003, 05:51
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