FW: Machine Code

FW: Machine Code

[Landon Blake]

Is it possible to write machine code instruction directly to the
computers memory without using an assembler? Is there an open source
"binary file" editor that someone can recommend that will allow me to do
this?

Do chip manafacturers typically provide an assembler that compiles
assembly language instructions into the machine code for there
processor, or does a programmer have to rely on third parties for the
assemblers?

I'm just wondering if it is possible to write a machine code file
directly without the need for an assembler.

Landon

Re: FW: Machine Code

[Brian Raiter]

> Is it possible to write machine code instruction directly to the
> computers memory without using an assembler? Is there an open source
> "binary file" editor that someone can recommend that will allow me
> to do this?

Are you trying to write instructions to memory or to a file? Assuming
a file, various binary file editors do exist, yes. The traditional
name for them is "hex editor", so you'd probably have better luck
searching for that. emacs has a hexl-mode as well.

You can also use Nasm as a sort of power hex editor, by specifying the
bin output format. This will give you total control over the bytes of
the output file while still allowing you to make use of the
assembler's higher-level features.

Note, though, that Linux doesn't have a ".bin" file format like MS-DOS
that consists entirely of machine code. ELF executable files require a
fair bit of overhead.

> I'm just wondering if it is possible to write a machine code file
> directly without the need for an assembler.

Nothing about Unix executable file formats is proprietary knowledge.
You could build your own copy of the Linux kernel manually, using a
hex editor instead of an assembler. It would probably take you months
of full-time work, but it's certainly possible to do.

b

Re: FW: Machine Code

[Claudio Fontana]

--- Landon Blake <lblake@ksninc.com> ha scritto: 
> Is it possible to write machine code instruction
> directly to the computers memory
> without using an assembler? Is
> there an open source "binary file" editor

memory or file?

> that someone can recommend that will allow me to do
> this?
> 
> Do chip manafacturers typically provide an assembler
> that compiles assembly language instructions into
the machine code
> for there processor, or does a programmer have to
rely on
> third parties for the
> assemblers?

There are assemblers provided by various parties,
manufacturer included, for popular architectures and
operating systems.
 
> I'm just wondering if it is possible to write a
> machine code file
> directly without the need for an assembler.

sure.
For small trivial tasks (change one opcode, change
static data) I use xxd and xxd -r (the reverse
operation of xxd, a data dumper similar to od).

man xxd

> Landon

CLaudio



		
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Re: FW: Machine Code

[Ricardo Nabinger Sanchez]

Quoting  "Landon Blake" <lblake@ksninc.com>
Sent on  Mon, 12 Dec 2005 11:55:06 -0800

> I'm just wondering if it is possible to write a machine code file
> directly without the need for an assembler.

yes, you want to look at these:

	http://www.cag.lcs.mit.edu/dynamorio/
	http://www.cag.lcs.mit.edu/rio/

regards.

-- 
Ricardo Nabinger Sanchez
GNU/Linux #140696 [http://counter.li.org]
Slackware Linux + FreeBSD

  Left to themselves, things tend to go from bad to worse.