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EEVBlog 121GW Multimeter Firmware Details

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Brumby:

--- Quote from: tpw_rules on January 28, 2018, 03:09:52 am ---For now, I just hand-assembled ARM instructions and patched the binary. It's a lot easier because the compiler wasn't very efficient and so space can easily be made for new code.
--- End quote ---

It's been a lot of years since I've done that - and it was on a systems module on an IBM mainframe.

Making the change isn't all that difficult - it's knowing that you haven't broken something in doing so that is the challenge.  The decompile would have helped immensely ... I had to do mine from a hex dump.


The big thumbs up comes from doing this without being able to test it on meter.   :-+ Champion stuff.

Fungus:

--- Quote from: Brumby on January 28, 2018, 11:58:11 am ---
--- Quote from: tpw_rules on January 28, 2018, 03:09:52 am ---For now, I just hand-assembled ARM instructions and patched the binary. It's a lot easier because the compiler wasn't very efficient and so space can easily be made for new code.
--- End quote ---

It's been a lot of years since I've done that - and it was on a systems module on an IBM mainframe.

--- End quote ---

Bonus points for doing it in a EPROM where you can only change 1s to 0s.

(I did that once)

bicycleguy:

--- Quote from: tpw_rules on January 28, 2018, 03:09:52 am ---...


--- Quote from: bicycleguy on January 28, 2018, 02:43:46 am ---1.  Looks like C++ because I see the word 'class' around a lot.  Is this why you commented 'everything is global' ie. the decompiler put all the class object data in one big pile?

--- End quote ---

Um I'm not sure where you've seen the word 'class'. I did a search of the repo and could not find that word anywhere. What I mean by 'everything is global' is that there are several functions (e.g. meas_ohms_calc_50M_offset(digits, factor)) where all the intermediate variables are stored as globals and only read/written in that function. This makes no sense and I'm pretty sure it can't be caused by the compiler.

--- End quote ---
|O I'm not sure where I got that from either, probably a brain fart although the vapors are still hanging, sorry.

The top of the 'EEVBlog-102.c':

--- Code: ---/* This file has been generated by the Hex-Rays decompiler.
   Copyright (c) 2007-2014 Hex-Rays <info@hex-rays.com>
   Detected compiler: GNU C++
*/

--- End code ---
I guess this means the GNU C++ compiler was used, not that the code is C++ ?

exe:
Sorry, I'm a bit late to the party. Is there a version of decompiled sources that could be modified a compiled? Or people directly modify binary code?

tpw_rules:

--- Quote from: exe on January 30, 2018, 09:16:03 am ---Sorry, I'm a bit late to the party. Is there a version of decompiled sources that could be modified a compiled? Or people directly modify binary code?

--- End quote ---

It would in theory be possible to recompile the source from the decompiler but I don't know how actually feasible it is. I've just been hand-assembling and patching the binary. I would like to see the sources recompiled at some point though.

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