Look up table generation

Hi!

Commit 2996dcdc03e872c1534c15750a9f741c6afffbc0 [1] from the portable 
sndio repository added a new resampling algorithm. Unfortunately, the 
origin of the lookup table isn't clear. Would it be possible to include 
either the script used to generate it (as well as other LUTs in the 
code), or some reference links?

Furthermore, would you be interested in patches to try and decrease the 
amount of duplicated code between aucat/ and sndiod/, if it doesn't 
prove too complicated to do?

[1] 
https://github.com/ratchov/sndio/commit/2996dcdc03e872c1534c15750a9f741c6afffbc0

Thanks,
Érico