Switch between sections?

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MUFOS

Joined: 17 Apr 2016
Posts: 47

MUFOS

Hey there.

I was wondering how I switch between sections. Writing "section '.data' data readable writeable" different places (between code sections) just create a new data section.

What I thought was that everything with the same section name would go into the same section -- however, that is not the case.

Any idea how I can achieve this?

29 Apr 2017, 13:59

VEG

Joined: 06 Feb 2013
Posts: 81
Location: Minsk, Belarus

VEG

AFAIK, it is not possible with FASM1. But it will be possible to write such "section" macros for the FASMG. I have no working code, but the idea of generation of data non-consequentially and insertion of the result in a specific place of the file was demonstrated here. I think that this technique can be used for collecting machine code for sections from different places of the source file also.

29 Apr 2017, 15:00

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 7845
Location: Kraków, Poland

Tomasz Grysztar

MUFOS wrote:

I was wondering how I switch between sections. Writing "section '.data' data readable writeable" different places (between code sections) just create a new data section.

This has been discussed numerous times on this board. If you'd like to see some older discussions you may start here: https://board.flatassembler.net/topic.php?t=9934

VEG wrote:

AFAIK, it is not possible with FASM1. But it will be possible to write such "section" macros for the FASMG. I have no working code, but the idea of generation of data non-consequentially and insertion of the result in a specific place of the file was demonstrated here. I think that this technique can be used for collecting machine code for sections from different places of the source file also.

This was possible with fasm 1, just not as easily. In the threads where combining data sections is discussed you may find several examples. And in the thread you mentioned I did share a link to the macros with Boyer-Moore-Hornspool search for reusable strings I once wrote for fasm 1, which I still have not ported to fasmg.

29 Apr 2017, 15:44

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17857
Location: In your JS exploiting you and your system

revolution

MUFOS wrote:

I was wondering how I switch between sections. Writing "section '.data' data readable writeable" different places (between code sections) just create a new data section.

What I thought was that everything with the same section name would go into the same section -- however, that is not the case.

Any idea how I can achieve this?

You can also use a linker to merge sections of the same type if you use a object file output format.

29 Apr 2017, 16:40

MUFOS

Joined: 17 Apr 2016
Posts: 47

MUFOS

revolution wrote:

MUFOS wrote:
I was wondering how I switch between sections. Writing "section '.data' data readable writeable" different places (between code sections) just create a new data section.

What I thought was that everything with the same section name would go into the same section -- however, that is not the case.

Any idea how I can achieve this?
You can also use a linker to merge sections of the same type if you use a object file output format.

How?

29 Apr 2017, 20:04

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17857
Location: In your JS exploiting you and your system

revolution

Have a look at the MSCOFF.ASM example included in the download. Add all your sections in any order you please. Assemble the file to a .obj file. Then use your linker to make the final .exe file.

30 Apr 2017, 05:44

rugxulo

Joined: 09 Aug 2005
Posts: 2341
Location: Usono (aka, USA)

rugxulo

revolution wrote:

Then use your linker to make the final .exe file.

In other words, this is specific to your linker, so check your docs:

Linker Options - MSDN - VS2015

02 May 2017, 00:30

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