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Re: Patch fixed strings in .hex file

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On 17/01/2024 08:45, pozz wrote:
> Il 16/01/2024 19:35, Hans-Bernhard Bröker ha scritto:
>> Am 16.01.2024 um 13:19 schrieb pozz:
>>
>>> I'm wondering how to detect the exact positions (addresses) of serial 
>>> numbers to fix.
>>
>> You do not.
>>
>> Instead, you set up linker scripts, linker options and/or add 
>> __attribute(()) to the variables' definitions to _place_ them at a 
>> predetermined, fixed, known-useful location.
> 
> Do you mean to choose by yourself the exact address of *each* string? 
> And where would you put them, at the beginning, in the middle or at the 
> end of the Flash? You need to calculate the address of the next string 
> from the address *and length* of the previous string. It seems to me a 
> tedious and error-prone job that could be done easily by the linker.
> 

How many strings do you need here?

While it is possible to do all this using patching of odd places in your 
file, using specific locations is often a better choice.  Since you 
haven't already said "Thanks for the advice - I tried it that way, it 
worked, and I'm happy" in response to any post, I would say that now is 
the time to take fixed location solutions seriously.

The way I always handle this is to define a struct type of fixed size, 
containing all the information that might be added post-build.  That can 
be version information, serial numbers, length of the image (very useful 
if you tag a CRC check on the end of the image), etc., - whatever you 
want to add.  Strings have fixed maximum sizes and space.

Make a dedicated section, and in the source code have a default instance 
of the type in that section, with default values.  (This is especially 
handy when running from a debugger, as your elf file will not have 
post-build values.)  Empty strings should be all null characters. 
Remember to declare it "volatile const".  Your linker file specifies 
that this section goes at a specific known fixed address (perhaps just 
after interrupt vectors, or whatever is appropriate for your 
microcontroller).

Now your post-build scripts have a simple fixed address to patch the 
binaries.

> 
>> And do yourself one favour: have only _one_ instance of that number in 
>> your code.  Use concatenation or similar to output it where needed.
>>
>> Then you can use tools like srecord GNU binutils to stamp your desired 
>> number into that fixed location in the hex file.  Professional-grade 
>> chip flashing tools for production environments can usually do that by 
>> themselves, so you don't even have to edit your "official" files.
>>
>> Details will obviously vary by tool chain.
>>
> 
> Patching the .hex or .bin file replacing 8 bytes starting from a known 
> address is simple. I would write a Python script or would use one of 
> srecord[1] tools.
> 
> [1] https://srecord.sourceforge.net/
> 

Don't bother with hex or srec files.  Use binary files - it makes things 
easier.

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Thread

Patch fixed strings in .hex file pozz <pozzugno@gmail.com> - 2024-01-16 13:19 +0100
  Re: Patch fixed strings in .hex file David Brown <david.brown@hesbynett.no> - 2024-01-16 13:51 +0100
    Re: Patch fixed strings in .hex file pozz <pozzugno@gmail.com> - 2024-01-16 15:42 +0100
      Re: Patch fixed strings in .hex file David Brown <david.brown@hesbynett.no> - 2024-01-16 16:36 +0100
        Re: Patch fixed strings in .hex file pozz <pozzugno@gmail.com> - 2024-01-16 16:57 +0100
      Re: Patch fixed strings in .hex file dalai lamah <antonio12358@hotmail.com> - 2024-01-16 16:47 +0100
        Re: Patch fixed strings in .hex file David Brown <david.brown@hesbynett.no> - 2024-01-16 18:50 +0100
  Re: Patch fixed strings in .hex file Herbert Kleebauer <klee@unibwm.de> - 2024-01-16 15:07 +0100
    Re: Patch fixed strings in .hex file pozz <pozzugno@gmail.com> - 2024-01-16 15:42 +0100
  Re: Patch fixed strings in .hex file Grant Edwards <invalid@invalid.invalid> - 2024-01-16 15:24 +0000
    Re: Patch fixed strings in .hex file David Brown <david.brown@hesbynett.no> - 2024-01-16 16:38 +0100
      Re: Patch fixed strings in .hex file Grant Edwards <invalid@invalid.invalid> - 2024-01-16 18:32 +0000
    Re: Patch fixed strings in .hex file pozz <pozzugno@gmail.com> - 2024-01-16 17:01 +0100
  Re: Patch fixed strings in .hex file David Brown <david.brown@hesbynett.no> - 2024-01-16 16:39 +0100
    Re: Patch fixed strings in .hex file Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2024-01-17 20:19 +0200
  Re: Patch fixed strings in .hex file Stefan Reuther <stefan.news@arcor.de> - 2024-01-16 17:44 +0100
    Re: Patch fixed strings in .hex file Grant Edwards <invalid@invalid.invalid> - 2024-01-16 18:39 +0000
    Re: Patch fixed strings in .hex file Michael Schwingen <news-1513678000@discworld.dascon.de> - 2024-01-16 19:30 +0000
  Re: Patch fixed strings in .hex file Hans-Bernhard Bröker <HBBroeker@gmail.com> - 2024-01-16 19:35 +0100
    Re: Patch fixed strings in .hex file pozz <pozzugno@gmail.com> - 2024-01-17 08:45 +0100
      Re: Patch fixed strings in .hex file pozz <pozzugno@gmail.com> - 2024-01-17 09:07 +0100
      Re: Patch fixed strings in .hex file David Brown <david.brown@hesbynett.no> - 2024-01-17 11:27 +0100
        Re: Patch fixed strings in .hex file pozz <pozzugno@gmail.com> - 2024-01-17 12:54 +0100
          Re: Patch fixed strings in .hex file David Brown <david.brown@hesbynett.no> - 2024-01-17 13:54 +0100
          Re: Patch fixed strings in .hex file Stefan Reuther <stefan.news@arcor.de> - 2024-01-17 17:39 +0100
            Re: Patch fixed strings in .hex file David Brown <david.brown@hesbynett.no> - 2024-01-17 18:28 +0100
            Re: Patch fixed strings in .hex file Grant Edwards <invalid@invalid.invalid> - 2024-01-17 19:00 +0000
            Re: Patch fixed strings in .hex file pozz <pozzugno@gmail.com> - 2024-01-19 09:10 +0100
      Re: Patch fixed strings in .hex file Hans-Bernhard Bröker <HBBroeker@gmail.com> - 2024-01-18 18:49 +0100
  Re: Patch fixed strings in .hex file pozz <pozzugno@gmail.com> - 2024-01-17 09:57 +0100
  Re: Patch fixed strings in .hex file Don Y <blockedofcourse@foo.invalid> - 2024-01-17 10:03 -0700
  Re: Patch fixed strings in .hex file Paul Rubin <no.email@nospam.invalid> - 2024-01-17 21:42 -0800

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