Magic File for TMS320 series DSP object files

Why should I care?

If you have not discovered the file command yet, you're missing out on a handy tool for identifying all sorts of binary files. Check the man pages-- it's installed on most Unix-like systems.

To illustrate the power of file, I ran file on a random collection of TI DSP object files lying around on my hard drive:

$ file -m ti-coff.magic *.o*
crt0_3sr.o:        COFF v2 executable, TI TMS320C30/C31, relocatable, local symbols
crt0_4sr.o:        COFF v2 executable, TI TMS320C40/C44, relocatable, local symbols
daa.obj:           COFF v2 executable, TI TMS320C54x, relocatable, line numbers, local symbols
daa.out:           COFF v2 executable, TI TMS320C54x, linked, line numbers, local symbols, entry point=0x1ae
vectors.obj:       COFF v2 executable, TI TMS320C6x, relocatable, line numbers, local symbols
cnfdsp_nohost.obj: COFF v2 executable, TI TMS320C6x, relocatable, line numbers, local symbols
cnfdsp_nohost.out: COFF v2 executable, TI TMS320C6x, linked, line numbers, local symbols, entry point=0xb920

The files are properly identified, and you don't even have to resort to using objdump to get basic attributes from each.

How do I use it?

As shown above, simply pass the path of the magic file snippet with -m, and then list the files of interest.

If you find yourself using this command often, it is easier to incorporate the "magic" file into your system-wide magic database. There are only a few steps involved:

1. Locate your magic file. Typical places are /usr/share/magic and /usr/lib/magic. Use the output of grep magic $(which file) if you're stuck.
2. Make a backup in case you hose the file while editing.
3. Insert the contents of ti-coff.magic somewhere near the top of the file (search for "Localstuff"). Be sure not to insert the file in the middle of a group of non-comment lines. (Comments are delimited with hash marks.) Add extra newlines around the inserted file.
4. If you have a recent version of file, you may have an additional data file named magic.mgc. If this is the case, run file -C as root to compile your newly edited magic file.

How does it work?

Check the magic file format man page (man 5 magic, but you can probably leave out the section number) and take a look at the code. It is a simple if-then matching structure, although it is admittedly not very self-explanitory. The magic numbers were culled from various TI COFF reference documents.