FirLp .cpp and .h are source files for a C++ class that sets up arrays and coefficients for a fir filter, performs the
filtering, and includes a short routine to copy the coefficients.

It implements filters of any length, and has filter windowing options of
Hamming, Hanning, and Blackman.  It makes it very easy to set up multiple filters, change, them, etc.  

Example:
To setup a 1024 pt filter, .001 cutoff, Blackman windowed:
CFirLp fir1(1024, .001, BLACKMAN);

To use:
y = fir1.Fir(x); // y is filtered output, x is new input value