Sat Dec 8 16:24:02 CET 2007

generic lowpass filters

it's no longer managable to have these special 1 * 2^(-8) filters.. i
need a special purpose 16bit lowpass filter, with saturation,
operating on proper 16 bit signed values, with possibly 8 bit
coefficients in a decent range.

it looks like there's plenty of room to do it in a proper
object-oriented fashion.

not doing it in proper object-oriented fashion, but a macro operating
on 4-byte state: 3 byte signed filter state, and 1 byte unsigned
filter coefficient: .00AA