CIL is a frontend for the C programming language which facilitates program analysis and transformation. CIL will parse and typecheck a program, and compile it into a simplified subset of C. For example, in CIL, all looping constructs are given a single form and expressions have no side effects. This reduces the number of cases which must be considered when manipulating a C program. CIL has been used for a variety of projects, including CCured, a tool which makes C programs memory safe. It supports ANSI C, as well as most of the extensions of the GNU C and Microsoft C compilers. A Perl script acts as a drop-in replacement for either gcc or Microsoft's cl, and allows merging of the source files in your project. Other features include support for control-flow and points-to analyses.
CPC (Continuation Passing C) is a programming language designed for writing concurrent systems. The CPC programmer manipulates very lightweight threads, choosing whether they should be cooperatively or preemptively scheduled at any given point; the CPC program is then processed by the CPC translator, which produces highly efficient event-loop code. This approach gives the best both worlds: the relative convenience of programming with threads, and the low memory usage of event-loop code. The semantics of CPC is defined as a source-to-source translation from CPC into plain C using a technique known as conversion into Continuation Passing Style. The current implementation of CPC has been used to write Hekate, a BitTorrent seeder designed to handle millions of simultaneous torrents and tens of thousands of simultaneously connected peers.