Tools to view the C code ?

You'll have to re-explain what it is you're trying to do. C generally doesn't come in diagrams, so there wouldn't be anything to "view". What this takes is to parse existing C, and *turn* it into diagrams. And that's where the really tough question would come up: *what type* of diagrams? You could be thinking of Nassi-Shneiderman structograms, some kind of SA/SD design diagrams, or even UML, for goodness' sake!

Maybe he's talking about ctree or calltree or something like that. Or ctags which show where something is defined.

-Dave

Not quite. UML is meant to be used for object-oriented analysis and design. It doesn't matter all that much whether the implementation is done in an OO language.

Turning this around, it means that if the program under study, like the vast majority of embedded C code, was designed with no regard whatsoever to OO patterns and styles, odds that reverse-UML-ing it would produce a useful view of the program are slim.

C code tends to be either hacked together without any design to speak of, or designed along the structured analysis/structured design (SA/SD) paradigm. OO designs can generally be implemented in C, but most C doesn't come from such roots.

I found Development Assistant for C very useful, a few years ago.