Hello Mr. Patrick Duggan,
There is an article entitled
Introduction to Digital Filters
By Brian Wagner and Michael Barr
Embedded Systems Programming
(11/19/02, 12:43:23 PM EDT)
at the following web site. It
includes c source code. Maybe
this could be useful.
http://www.embedded.com/story/OEG20021119S0020
Good luck.
Regards,
Charles Bannister