Just want to add that GMP is not "C". The critical parts are written in assembly. It's not really possible to do fast multiple-precision arithmetic in C. You need direct access to add with carry instructions and the like.
Your nick sounds familiar. "richtea" I'd say I remember but no idea from where.
Yeah I'm sorry that my comment from late 2014 gave that false impression that I said GMP was written in C. What I meant was that it was, when I did the testing, slightly faster to call GMP from C than from Haskell, Clojure, Java. I remember I tried all these back then and calling GMP for C was a bit more efficient. Now I know there are now ways to call libs like this from Java without paying the old foreign function call penalty: but I didn't know about that in 2014. So I called GMP from C because it was faster. Out of memory I'd have said GMP was C with inline assembly but I may be wrong ; )
