Conventions for modelling c programs.

Question

I'm working with a source base written almost entirely in straight-c (nginx). It does, however, make use of rich high level programming techniques such as compile-time metaprogramming, and OOP - including run-time dispatch.

I want to draw ER diagrams, UML class diagrams and UML sequence diagrams. However to have a clean mapping between the two, consistent conventions must be applied. So, I am hopping someone has some references to material that establishes or applies such conventions to similar style c-code.

Edit

Well, the question is quite specific, and as such I do not expect useful answers anytime soon.

I have started reading excerpts from the book "code reading - an open source perspective" by Diomides Spinelles. The book is written to to teach the art of reading the code of large complex systems, straight-c seems to be the dominant language used for the book. UML is introduced as the modelling language of choice in the first chapter.

I believe I should be able to follow the conventions established in this book.

Answer 1

Class-like function orgranisation of code in C is used often. According to this "Class pattern" for procedural languages functions are prefixed with "class" name. One can also distingish among contructor, accessor and mutator functions. Mapping of these things to UML class diagrams is straightforward. Again, this pattern is quite common nowadays, so it is worth drawing.

UML sequence diagrams cannot be applied directly to C functions, since there is no reciever object like this in C++ that can be represented as a bar with a vertical line. So one could use plain old call graphs instead of UML sequence diagrams. I guess there are some ways to somehow express call graphs right in UML, but it might be not so convenient.

It is quite common to see implicitly defined finite state machines (FSMs) in C code. Although they cannot be expressed in C directly, in many situations developers use them to structure their control logic. Such instances of the "FSM pattern" also can be extracted from C sources and drawn as UML statechart diagrams.

And last, but not least, the visual representation of file decomposition can be quite informative. One could use the UML package diagram for this purpose, where packages include functions and static data.