ELF file: linking in large binary data

Convert your binary image to whatever data structure you like (in human readable form, mind you), compile, link and presto... That's what I do, whenever the use of files is undesirable if not impossible.

BCNU

Waldemar

"Will Barry" schreef in bericht news: snipped-for-privacy@posting.google.com...

armasm will let you include binary files using INCBIN.

Wilco

Thanks! But the file I would like to link with the executable is really large, like 100K+ or so. So converting manually is out of the question. But then writing the program to generate the binary data into a pre-initialized C array form would not be difficult. This is going to be my fallback if I can't find an easier way. I appreciate your reply!

Will Barry

Thanks! Also, fyi, I took the liberty of searching for your keywords 'armasm' and 'INCBIN' in google. I found a link in the arm.com website regarding the utility called bin2aof. This program converts any binary file into a format that can be linked in with the executable.

Thanks again. Will =>barry

Why bother? Just let the executable read the file into an array in its own data space on startup. Much more flexible, and no opportunity for translation foulups.

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Read the file from where? None of the embedded systems I've ever worked on had filesystems.

But it requires a filesystem, which is a huge amount of overhead when all you want is an initialized data structure.

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Grant Edwards                   grante             Yow!  Hello... IRON
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Thanks for all the replies.

That is correct, I don't have a filesystem. So I guess the only place to store the binary data is together with the executable. I'm currently playing around with the INCBIN armasm directive which Wilco suggested. According to the documentation, this directive links a raw binary file into the generated object file as is, with no interpretation. This looks like an easy way to do it. I'm gonna try it and see how it works...

Most systems have some sort of rudimentary filesystem, even if it is not recognizable as such. Especially systems that need 100k of raw data. What is the system that transfers that load module into runnable code space, and what is used to implement stdin and stdout (if any). If the system is doing any user interaction, it has a file system.

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Chuck F (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net)
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Huh? I've been doing embedded systems stuff for 25 years and have never worked on anything that had any sort of filesystem (even rudimentary).

Huh? I burn my "load modules" into ROM.

Nothing! There is no filesystem. There sometimes is a function I can call to write a string to a UART, but it's not a filesystem.

That's complete nonsense.

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Lets see one system transfers and verifies 640KB into real time video run space. Another transfers 128KB into a different form of dual ported RAM, both use DMA.

One system has a tracking camera and a rarely used toggle switch for user interaction.

Another has 6 LEDs and two touch switches.

Both have a 16bit code set in the 64KB to 128KB size and NO file I/O especially in NO way related to user I/O.

Debug has a very rudimentary Command Line Interpreter, with no file i/o system there.

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Paul Carpenter          | paul@pcserviceselectronics.co.uk
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I always use that technique, myself. I usually do it in python or Matlab, rather than C, because that's easier to tweak and still easy to make part of the build process (make files). It also has the advantage that it's easy to perform numerical-domain transformations on the data on the way, like quantization and rounding.

However, since you're dealing with images, it might interest you to know that the original default PNM (portable-any-map) or pbm image transformation library format was in fact syntactically a C array initializer. That might be a convenient pre-built tool for the job. Lots of original X-windows programs compiled all of their icons in, even though they would most likely be running on machines with file systems, to avoid the problem of ensuring that the path to the directory containing the icons/images was properly configured. So there's actually plenty of experience out there in existing code...

I still don't understand why some object file formats (COFF?) are so baroque about these things, though. On one platform that I've used, the COFF image of a constant initialized array was several orders of magnitude larger than the original...

Cheers,

--
Andrew

Have you looked at using GNU objcopy to create object files from your binaries?

-a

It seems that you have been infected by the rotten Unix I/O ideology for a too long time :-) :-).

So apparently any sequence of two or more bytes would be a file system. Thus, a 16-32 bit processor with en 8 bit data bus (such as

68008) would have a file system since multiple bytes are transferred in sequence to get a word transfer.

Why not take the idea even further and define that any sequence of bits is a file system. Thus, even a UART sending _only_ the SYN character at regular intervals would have a file system.

On an embedded system, that systems that transfers the load module is often a human hand moving the EPROM from the prommer to the embedded system PROM socket.

What is the point of having these channels, if you do not have anywhere to connect them.

So a system that only reads a switch (on a safety gate that shuts down the system, if someone tries to enter a hazardous area) is a file system ?

Paul

We don't need to do that --- there already are enough people (including some vintage CS professors) who go around stating that "everything is a database", and they actually mean it. Classic case of new hammer syndrome, if you ask me.

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Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
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The most portable way of doing this is to write a C program that generates a C array declaration. This is in fact the exact format of the X11 bitmap and pixmap files.

You really don't want to mess with ELF by hand (assuming your toolchain builds an ELF object which you process with something like `objcopy -O binary'). ELF is arcane beyond belief.

If your data is Too Big for that (but 100KB isn't that bad) I'd make a stub C file that builds an array with a magic number that you can find and overwrite:

char data[SIZE] = { 'm', 'a', 'g', 'i', 'c' };

The magic serves two purposes: That's how you find it with your data-stamping program, and also it forces the array into data space so you don't just get a bunch of ELF gunk and no array.

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Ben Jackson

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Well, in the past my systems consisted of code that interacted with the outside world in some manner. They had no disk file systems, but they did read switch contacts, A/D converters and the ilk, and they output information to such things as leds, even displays, lans, etc. All those things appeared as the specialized file system for that particular application. The connections were implemented as drivers for the devices. Devices could be brought on (and off) line (connected to the interrupt system) by opening (and closing) files.

This was a great convenience, since I could capture a run of the device to actual disk files, and re-run any problems indefinitely, measure response times, etc. ad nauseam.

I suggest you stop thinking of files in such a limited manner, but rather as the communication path between the world and your software. Without such the software is totally useless. By abstracting that interface you will have many more abilities.

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Chuck F (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net)
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     USE worldnet address!

Such an arrangement can be very useful - that's one of the nice things about working with a *nix system. It is also possible to make such an abstraction even without a *nix OS. But no matter how it is done, it takes a lot of overhead. In "big" embedded systems, it is probably worth it for the flexibility and convenience, while in "small" systems it is not. So while most of the systems *you* have worked with have some sort of filesystem, I think most of the systems used regularly by people in this group have no filesystem of any sort.

That's a very, uh, unique way of doing things. I've never heard of anybody implimenting a filesystem so they can read a pushbutton switch or turn an LED on/off before.

I guess I don't see how being able to open/close an I/O device makes it into a filesystem.

So an LED is a filesystem. You've redefined the word filesystem so broadly that it's become meaningless.

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Grant Edwards                   grante             Yow!  I'm receiving a coded
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Which doesn't make it any less true, just as every wire is a transmission line. The problem is to know when to apply the simpler approximations. Similarly, I suspect very few ships adjust for relativaty path distortion in their navigation, although the GPS satellites very well may do so.

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Chuck F (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net)
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     USE worldnet address!