FIR filter coefficents WITHOUT FUCKING MATLAB

Having recently bought a radio scanner (a UBC72XLT), I'm having a go at writing a morse transmission decoder. I've tested it all working in theory by booting into Windows and using a shareware CW decoder, but the preference would be for longer-term decoding with the machine's normal OS (NetBSD).

Now to start off, I need a tunable digital bandpass filter, settable from anywhere from 600Hz to 1200Hz (the nearest Morse practice station is 916Hz). A FIR filter would do the trick... except EVERYTHING I GOOGLE SAYS CALCULATE THE COEFFICIENTS USING MATLAB'S REMEZ FUNCTION AND HARDCODE THOSE VALUES IN LOL.

As a last resort there's remez libraries around, but I'm not about to bolt 60kB of code I don't understand onto the project. How on earth did they calculate FIR coefficients before fucking MathsWorks came along? (and yes, I Google for that and a hundred variations to the question too. comp.dsp is a shitheap of unanswered questions...)

I added one term to the above search and got this: http://www.watri.org.au/~ajh/libfilth/

If that's still not good enough, go take apart one of the open-source implementations. If you're writing your own program, this shouldn't be a problem.