DromeAudio is a small audio manipulation and playback library. It features a simple API for loading, generating, processing, and playing audio. Some of its features include loading and saving WAV sounds, loading Ogg Vorbis sounds, audio mixing/playback, and dynamic audio processing effects such as pitch shifting and echo.
Ctpp is the C99-compatible C preprocessor of the Ctalk language, which provides object oriented extensions for C. The preprocessor is compatible with GNU cpp and provides extensions like macro expansion in warning and error messages, saving expanded macros to files, and built-in symbol definition for many command line options. You can download the preprocessor separately while Ctalk is between versions for development.
SINGULAR is a computer algebra system for polynomial computations in commutative algebra, algebraic geometry, and singularity theory. Its main computational objects are ideals and modules over a large variety of baserings. The baserings are polynomial rings over a field (eg. finite fields, the rationals, floats, algebraic extensions, transcendental extensions), or localizations thereof, or quotient rings with respect to an ideal. It features fast and general implementations for computing Groebner and standard bases, including Buchberger's algorithm and Mora's Tangent Cone algorithm. Its interactive shell and C-like programming language can be extended by libraries written in the SINGULAR programming language.
LibGC is a small, fast, portable, multi-threaded garbage collection library for C++. It is highly customizable, as it can be multithreaded or single threaded, and the memory size to use for the collector may be changed at compile time. It is precise, as it only scans pointers that exist as members on the stack or as global variables. It's very easy to use, since it has only two classes, Object (the base class for garbage-collected objects) and Pointer (for garbage-collected pointers).
The POCO C++ Libraries are a collection of class libraries for developing network-centric, portable applications in C++. The classes integrate perfectly with the C++ Standard Library and cover functionality like threads, thread synchronization, filesystem access, streams, shared libraries and class loading, sockets and network protocols (HTTP, FTP, SMTP, etc.), including an HTTP server, as well as an XML parser with SAX2 and DOM interfaces and SQL database access.
The pl1gcc project is an attempt to create a native PL/I compiler using the GNU Compiler Collection. PL/I is a third-generation procedural language suitable for a wide range of applications including system software, graphics, simulation, text processing, Web, and business applications.