A problem with defining a macroinstruction [equ if match]

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Sasha

Joined: 17 Nov 2011
Posts: 93

Sasha 17 Nov 2011, 22:05

I defined the macroinstruction this way, and it worked ok.

Code:

        macro Exit arg1{
                if arg1 eq
                        invoke  ExitProcess, eax
                else
                        invoke  ExitProcess, arg1
                end if
        }

But in the case of more complex function calls I don't want to write this code twice and I tested this option:

Code:

        arg2 equ eax
        push arg2

This code has been compiled ok.
But in case of using this inside the macroinstruction like this

Code:

        macro Exit arg1{
                if arg1 eq
                        tmp1 equ eax
                else
                        tmp1 equ arg1
                end if              
                invoke  ExitProcess, tmp1
        }

The fasm compiled it without any errors, but I have got the wrong code like:

Code:

        call [ExitProcess]

Without pushing an argument!
I continued to look for a solution and did this:

Code:

        macro Exit arg1{
                if arg1 eq
                        tmp1 equ eax
                else
                        tmp1 equ arg1
                end if              
                push tmp1
        }

And here I get the fasm error: invalid operand. Instruction: push
So I understood that tmp1 in the case of arg1 eq is not equals to eax...
My questions are:
How can I solve this problem ?
Why fasm din't give any errors in the case of 'invoke'

17 Nov 2011, 22:05

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20289
Location: In your JS exploiting you and your system

revolution 17 Nov 2011, 23:45

You can't mix equ and if like that. All of the equs are processed first before the assembler sees the ifs. A solution is to replace the if blocks with match blocks (see the docs for how to use match). That way the equs will be processed at the same time as the matches.

17 Nov 2011, 23:45

edfed

Joined: 20 Feb 2006
Posts: 4330
Location: Now

edfed 17 Nov 2011, 23:49

why not just do something like this?

Code:

macro Exit arg1{
if arg1 eq
push eax
else
push arg1
end if
call [ExitProcess]
}

17 Nov 2011, 23:49

Sasha

Joined: 17 Nov 2011
Posts: 93

Sasha 18 Nov 2011, 00:13

edfed wrote:

why not just do something like this?

Code:

macro Exit arg1{
if arg1 eq
push eax
else
push arg1
end if
call [ExitProcess]
}

May be it's a good idea, but not for a procs with many arguments, i think..
And I want to stay with invoke. Thank you for explanation.

18 Nov 2011, 00:13

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