On Thu, 15 Mar 2007, Nick Andrew wrote: > I figure this may take only a minute for the right person, and > it can't hurt to ask, so ... > > I have a 3k firmware image for 8051. Is there anybody who can > disassemble this file for me? The file seems to contain some > code and some data, so naturally the disassembly will need to > deduce which is which. I think the first 3 bytes are a jump > instruction so there is a known code entry point. > > Nick.
Take a look at this: http://members.naspa.net/djs/software/dis51.html It can also be found here: http://home.earthlink.net/~davesullins/software/dis51.html It's a simple C program that disassembles 8051 code. You "suggest" to it the entry points to start from and it will follow through every jump it sees, hopping around through the code and hopefully skipping the unexecuted data. I have a version of this disassembler that I've heavily hacked on, where I can define symbols & text annotations to be interpolated into the output - great for interative exploration of a pile of opaque 8051 code. Typically what I've done is to feed it all the architecture-defined entry points for the various processor exception addresses (like for example the spot you suspect), look at what results, remove entry points that appear not to be in use (e.g. they disassemble into gibberish), try again, etc, etc. As I spot interesting looking functions, I'll tag those addresses with symbol names then run the disassembler again to see where else those symbols might surface. It's not perfect since I don't catch split instruction address calculations or computed gotos, but usually with enough bleary-eyed staring you can start to see a pattern - and if there's a computed goto in there it can be spotted from the telltale lookup table. Then I tag each table target with another fabricated symbol and iterate again. You can certainly start with the link above. If what you see from that looks promising, then if you ask nicely I might be convinced to pretty-up my hacks and make available the results on a web page. -Mike -- | Mike Isely | PGP fingerprint Spammers Die!! | | 03 54 43 4D 75 E5 CC 92 | isely @ pobox (dot) com | 71 16 01 E2 B5 F5 C1 E8 | | _______________________________________________ linux-dvb mailing list linux-dvb@linuxtv.org http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
