Recursion in macros

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Cgtk

Joined: 10 May 2020
Posts: 14

Cgtk

Hello, I need to implement a construction like this using fasm macros:

Code:

macros recursion{
random 1, 2; min, max
if random_result = 2
   recursion
end if

}

How i can do this?

11 Jul 2020, 17:13

DimonSoft

Joined: 03 Mar 2010
Posts: 894
Location: Belarus

DimonSoft

Cgtk wrote:

Hello, I need to implement a construction like this using fasm macros:
Code:
macros recursion{
random 1, 2; min, max
if random_result = 2
   recursion
end if

}
    
How i can do this?

First of all note that you mix preprocessor and compiler stuff. In this particular case you’ll have an endless recursion. Still, the general idea is the following: write a macro that defines your macro and call it before recursive call of the macro itself. For your case, it would look something like:

Code:

macro def_recursion
{
  macro recursion
  \{
    random 1, 2; min, max
    if random_result = 2
      def_recursion
      recursion
    end if
  \}
}

def_recursion

I write this directly in a browser (just like you do), so might make some mistake but the general idea is this.

11 Jul 2020, 19:44

Cgtk

Joined: 10 May 2020
Posts: 14

Cgtk

Thanks!

11 Jul 2020, 21:18

Roman

Joined: 21 Apr 2012
Posts: 993

Roman

And how use this macro ?

12 Jul 2020, 12:22

DimonSoft

Joined: 03 Mar 2010
Posts: 894
Location: Belarus

DimonSoft

Roman wrote:

And how use this macro ?

The first question is what the macro should do in the first place. I guess, this code was given just as a generic example of something that should happen inside. Like I said before, mixing preprocessor and assember features might make the macro in its current implementation useless and buggy.

12 Jul 2020, 15:51

Cgtk

Joined: 10 May 2020
Posts: 14

Cgtk

Hello again, I'm trying to implement a recursion construct like this

Code:


macro big_macros{

macro num_1 param1
\{
random 1, 2

if param1 = 1
   if randnum = 2
      num_2
   end if
end if
\}


macro num_2
\{

num_1 0  ; error here

\}
}

start:
   big_macros

The compiler throws the error: "illegal instruction"
What is wrong?

Last edited by Cgtk on 20 Jul 2020, 10:35; edited 1 time in total

19 Jul 2020, 19:46

DimonSoft

Joined: 03 Mar 2010
Posts: 894
Location: Belarus

DimonSoft

DimonSoft wrote:

First of all note that you mix preprocessor and compiler stuff.

19 Jul 2020, 21:20

Cgtk

Joined: 10 May 2020
Posts: 14

Cgtk

DimonSoft wrote:

DimonSoft wrote:
First of all note that you mix preprocessor and compiler stuff.

I am writing macros on fasm for the first time and don't know how to do it properly. Could you tell me how you can implement a macro similar in functionality to the macro that I described in the post earlier?

20 Jul 2020, 10:02

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17937
Location: In your JS exploiting you and your system

revolution

There is a problem here:

Code:

marco big_macros{

marco should be macro

Also use backslash \ to escape the curly brackets, not forward slash /

20 Jul 2020, 10:07

Cgtk

Joined: 10 May 2020
Posts: 14

Cgtk

revolution wrote:

There is a problem here:
Code:
marco big_macros{    
marco should be macro

Also use backslash \ to escape the curly brackets, not forward slash /

Oh, thank you, fixed the post with the code. Unfortunately this is just my typo in the example and the compiler is not swearing because of this.

20 Jul 2020, 10:34

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17937
Location: In your JS exploiting you and your system

revolution

Works for me.

Code:

1 passes, 0 bytes.

20 Jul 2020, 10:42

Cgtk

Joined: 10 May 2020
Posts: 14

Cgtk

Try to compile this

Description:		Download
Filename:	trashgen.asm
Filesize:	55.26 KB
Downloaded:	135 Time(s)

20 Jul 2020, 11:09

DimonSoft

Joined: 03 Mar 2010
Posts: 894
Location: Belarus

DimonSoft

Build your source code with Ctrl+F8 if you use FASMW IDE, then feed the fas-file to PREPSRC tool in the %FASM%\TOOLS\WIN32 directory (easily buildable from the source code). PREPSRC might give you sense of what is going on.

20 Jul 2020, 11:13

Cgtk

Joined: 10 May 2020
Posts: 14

Cgtk

DimonSoft wrote:

Build your source code with Ctrl+F8 if you use FASMW IDE, then feed the fas-file to PREPSRC tool in the %FASM%\TOOLS\WIN32 directory (easily buildable from the source code). PREPSRC might give you sense of what is going on.

I can't compile my code. The compiler throws the error: "illegal instruction".

20 Jul 2020, 11:25

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17937
Location: In your JS exploiting you and your system

revolution

Cgtk: Please reduce your code from the 55kB you posted there. Just post the necessary parts showing the problem.

20 Jul 2020, 11:34

Cgtk

Joined: 10 May 2020
Posts: 14

Cgtk

revolution wrote:

Cgtk: Please reduce your code from the 55kB you posted there. Just post the necessary parts showing the problem.

Description:		Download
Filename:	reducedcode.asm
Filesize:	1.71 KB
Downloaded:	119 Time(s)

20 Jul 2020, 11:52

Cgtk

Joined: 10 May 2020
Posts: 14

Cgtk

DimonSoft wrote:

Build your source code with Ctrl+F8 if you use FASMW IDE, then feed the fas-file to PREPSRC tool in the %FASM%\TOOLS\WIN32 directory (easily buildable from the source code). PREPSRC might give you sense of what is going on.

Sorry for a very stupid question, but what should I submit as an input and output file?

20 Jul 2020, 11:58

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17937
Location: In your JS exploiting you and your system

revolution

There is still a lot of extraneous stuff in there, but the error output shows that you are calling gen_trash_func from within itself.

You need to regenerate the macro within itself if you want to do a recursive call.

See the fasm win32ax.inc code for how allow_nesting does it.

20 Jul 2020, 12:04

Cgtk

Joined: 10 May 2020
Posts: 14

Cgtk

Thank you, I will definitely look at it.

20 Jul 2020, 12:15

DimonSoft

Joined: 03 Mar 2010
Posts: 894
Location: Belarus

DimonSoft

Cgtk wrote:

DimonSoft wrote:
Build your source code with Ctrl+F8 if you use FASMW IDE, then feed the fas-file to PREPSRC tool in the %FASM%\TOOLS\WIN32 directory (easily buildable from the source code). PREPSRC might give you sense of what is going on.

Sorry for a very stupid question, but what should I submit as an input and output file?

The fas-file you got as the input and any file name as output (it will be a text file with step-by-step explanations of what preprocessor sees and how does it (pre)process it).

20 Jul 2020, 13:35

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