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flat assembler > Macroinstructions > How to use PUSHD macro to push the offset?

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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 16733
Location: In your JS exploiting you and your system
The PUSHD macro (in WIN32AX.INC) has the following line:

Code:
  else if _ # first in <_addr first,_ADDR first>
    


And it appears as thought it is meant to allow the pushing of an offset.
So I tried the following:

Code:
 stdcall _foo,eax,19,ecx,addr [esi+_is.bar],addr [esi+_is.tar]
    


It does not work and I get compile error "error: undefined symbol."

How can I take advantage of the PUSHD macro to push the offsets?

I know I can manually use the following but it is ugly and not clear.

Code:
 lea edx,[esi+_is.tar]
 push edx
 lea edx,[esi+_is.bar]
 stdcall _foo,eax,19,ecx,edx
    
Post 06 Nov 2004, 03:03
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pelaillo
Missing in inaction


Joined: 19 Jun 2003
Posts: 874
Location: Colombia
pushd is not a macro, it is an instruction. Afaik, in order to push a non immediate offset (one that cannot be calculated at compile time), you will need lea as you do. The same construct is used by MASM when you use addr, the difference is that eax will be used.
Post 06 Nov 2004, 15:07
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Tomasz Grysztar
Assembly Artist


Joined: 16 Jun 2003
Posts: 7317
Location: Kraków, Poland
It should be
Code:
stdcall _foo,eax,19,ecx,addr esi+_is.bar,addr esi+_is.tar    
Post 06 Nov 2004, 16:03
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 16733
Location: In your JS exploiting you and your system
Oh yeah, I can see how it works now.

I had copied the PUSHD macro to my code but omitted to copy the line "addr equ".

The error I got was actually "addr symbol undefined", but I did not know because the error does not explicitly say which symbol was undefined.

Actually, since it came up, is it possible to get the error function in FASM to print which symbol it cannot find when such an error occurs?

Sometimes I find that a long stdcall line with many symbols can make tracing a "symbol undefined" error troublesome.
Post 06 Nov 2004, 16:45
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pelaillo
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Joined: 19 Jun 2003
Posts: 874
Location: Colombia
Where`s pushd macro?
Post 06 Nov 2004, 16:50
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 16733
Location: In your JS exploiting you and your system
Quote:

The PUSHD macro (in WIN32AX.INC) has the following line
Post 06 Nov 2004, 19:57
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pelaillo
Missing in inaction


Joined: 19 Jun 2003
Posts: 874
Location: Colombia
Embarassed thanks
Post 06 Nov 2004, 21:11
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