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phenix



Joined: 08 Feb 2009
Posts: 9
phenix
Hi All,
I'm looking for a place to park as I want to leave windowssssss.
I have been using MASM32 which is a flat assembler. By that I mean
it DOESN'T use segment registers. DOES fasm us segment registers
or is it a true flat assembler?
Thanks for any replies
Post 08 Feb 2009, 23:03
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17635
Location: In your JS exploiting you and your system
revolution
Erm, what do you mean?

The CPU uses segment registers, they are impossible to avoid. Windows sets them up for all flat access to memory but they are still there in the background.

fasm has a DOS version which uses FRM. So, just like Windows, the segment registers are set for flat memory access.
Post 09 Feb 2009, 01:30
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phenix



Joined: 08 Feb 2009
Posts: 9
phenix
Thanks for the reply.
I realize that the segment registers are still there.
When I used an old version of MASM I had to program for segments and
far jumps. That is not necessary in a true flat assembler. How does FASM
handle far jumps?
For instance MASM32 is a true flat assembler.
But alas it only works in Windows......
Post 09 Feb 2009, 01:56
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
fasm allows you to create flat binaries (no segments), ELF objects and executables (the ones used on Linux, FreeBSD, Solaris, etc), and Windows binaries. In all the mentioned cases the memory model is flat.

fasm also support the creation of MZ executables and those are segmented and for DOS only.

[edit]Better check the examples in the Windows package and also the Linux package to see by yourself how the coding is being done. Also, to understand how the windows headers work, check http://flatassembler.net/docs.php?article=win32
Post 09 Feb 2009, 02:16
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phenix



Joined: 08 Feb 2009
Posts: 9
phenix
I'm still confused about whether this assembler does short or far calls.
This would NOT make it a flat assembler.
I am not interested in 16 bit code.
Therefore I would be using 32 bit code and should NOT have to get involved in
short and far jumps.
From the reading I have done it is not clear what this assembler does.
Could someone clarify this for me, Please?
Post 12 Feb 2009, 22:58
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17635
Location: In your JS exploiting you and your system
revolution
32 code does not use far calls unless you code those instructions. All calls are near.
Code:
call [somewhere] ;near call, no segment used
call far [somewhereElse] ;far call because you told the assembler you want it
call anotherPlace ;direct call, cannot be far    
Post 12 Feb 2009, 23:44
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DOS386



Joined: 08 Dec 2006
Posts: 1901
DOS386
phenix wrote:
When I used an old version of MASM I had to program for segments and far jumps.


Problem specific to MASM or some 16-bit HLL compilers Wink

Quote:
That is not necessary in a true flat assembler. How does FASM
handle far jumps?


Not at all. FASM can compile all types of jumps you might need. No problem at all (except you need 16-bit OMF).

Quote:
I'm still confused about whether this assembler does short or far calls.


Calls can be near or far only. They are all near except you deliberately make them far. Jumps can be short, near or far. FASM makes them short whenever possible, otherwise near, and far only if you deliberately make them far. Also, there is no "memory model" (small, compact, medium, large, huge, insane) support/trouble in FASM.

Quote:
For instance MASM32 is a true flat assembler


We don't need FASM anymore Laughing

Quote:
But alas it only works in Windows......


RTFL Laughing
Post 13 Feb 2009, 07:46
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Tomasz Grysztar



Joined: 16 Jun 2003
Posts: 7782
Location: Kraków, Poland
Tomasz Grysztar
revolution wrote:
Code:
call anotherPlace ;direct call, cannot be far    

Well, direct call can be far, too. Wink And even in the long mode.
Post 13 Feb 2009, 09:58
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MazeGen



Joined: 06 Oct 2003
Posts: 977
Location: Czechoslovakia
MazeGen
Tomasz Grysztar wrote:
revolution wrote:
Code:
call anotherPlace ;direct call, cannot be far    

Well, direct call can be far, too. Wink And even in the long mode.

If you refer to opcodes 9A and EA, they are invalid in 64-bit mode. I was looking forward to report another bug, but FASM conforms to this rule Very Happy
Post 13 Feb 2009, 10:37
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Tomasz Grysztar



Joined: 16 Jun 2003
Posts: 7782
Location: Kraków, Poland
Tomasz Grysztar
Oh, right, I mistook it with opcode FF. Smile
So... I correct myself: except for the long mode. Very Happy
Post 13 Feb 2009, 10:40
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17635
Location: In your JS exploiting you and your system
revolution
I think because we never use far calls that we easily get confused about what can be done and what cannot. I mean honestly, who uses far calls these days, who? All those that use far calls shout out "me". ... ... ... <sounds of crickets chirping> ... ... I thought so. Wink
Post 13 Feb 2009, 11:05
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Madis731



Joined: 25 Sep 2003
Posts: 2140
Location: Estonia
Madis731
@phenix: You don't seem to agree that 'F' in FASM means 'flat'. This assembler's name comes from its capabilities. Is it really that hard to accept?
Post 13 Feb 2009, 11:25
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phenix



Joined: 08 Feb 2009
Posts: 9
phenix
Thanks guys for all the info.
It has finally dawned on me that FASM is a true flat assembler. Laughing
Post 13 Feb 2009, 13:25
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