This is an implementation of a 2-pole State Variable Multi-Mode Filter. With full GPL'd source code. It is completely useable as it is, or you may modify it.
in Version 0.1 simply adds together the inputs, then outputs a low-pass filtered version on the left channel, and a high-pass filtered version of the audio on the right channel. You can change the frequency using MIDI controller #1. In this initial version, the resonance is fixed.
download 2181 EZ-Kit Lite software w/ GPL'd source