This does look very much like C, but it doesn't look quite right to me to simply say that it is C. It definitely has an "attitude" associated with it. There are also lines scattered in there that look more like they are coming from a document (page footers & section headings) rather than from a source code file.
After a couple consultations with my friend Google, I have pinned it down.
This is not from a source code file. Some of these lines are not code. This is an extract from
this document[
^]. It is C code written as an add-in for a commercial software package, as you could have told from reading the beginning of the document.
This company[
^] seems to have bought, or be, the company that produced that software package. Which of their products is the one you are interested in, I'm not going to figure out for you.
Do note that this code is set up so that it can be compiled in different ways for different uses by changing #defines in the source code.
Beside a language change ( for what reason? ), you are evidently not going to be using the software package this was intended to work with. There is more going on here than "just" a conversion. I would say that the only converter that may work is a human who actually understands the situation you are dealing and can fill in what may be a lot of blanks.