This package includes yabba and unyabba, portable implementations of Y
coding. Y coding is unpatented---unlike the LZW coding used by compress
and the LZ78 variants used by most other dictionary compressors. Y also
gives somewhat better compression than LZW.

As an extra bonus, this package also includes whap and unwhap, portable
implementations of AP coding. AP coding is patented, but like Y it is
more effective than LZW. whap runs about as fast as compress and, in its
default configuration, uses less memory; unwhap runs as fast as
uncompress and uses less than half as much memory.

The entire package is public-domain. You can copy my Y code into any
application without fear of copyrights or patents. Be aware, however,
that the current implementation is probably not too close to optimal,
and I am actively searching for a better method. If AP were not patented
I would recommend that you use it instead. For more information see
PATENTS in the package.

---Dan Bernstein, brnstnd@nyu.edu
