LZS for ISDN for Linux
In 1998, I wrote a CCP backend module for the I4L ISDN implementation
that is somewhat compatible to LZS (RFC1974) compression, better known
as Stac. The solution is still in a BETA state, but has been used by a
number of people over the last years. Now that german mass dialin provider
T-Online started to officially support compression, and that compression
beeing LZS EXT mode, interest into the code bumped up suddenly.
I used to just publish the source I've written, but getting it into the
kernel was a task left to the user. This might not be much of a fuzz to
a kernel developer, but for the occasional user it is a bit hard.
Thanks to
Frank Elsner
there is a complete kernel patch available for some 2.2 and all 2.4
versions that can easily be applied by anyone able to patch and compile
the kernel.
The files
The individual files that are automatically installed at the right place
in the kernel source tree by the abovementioned patch are:
README.LZS The obvious README
ChangeLog Version change log
isdn_lzscomp.c The latest compression module source (includes multi history, builds on 2.6)
isdn_lzscomp.c.1.21 Old 2.4 version (for reference only)
isdn_ppp.diff Experimental patch to 2.2.19 (fixes MP)
Old stuff
Stuff that used to age around here has been moved to a
subdirectory. It is an older version of the module as
well as updates to code that should be in ipppd for years now. Traverse
only for nostalgia.
License
The code is Copyleft 1998-2001 by Andre Beck under terms of the
GNU GPL. While the
code is provided free and under GPL, it may infringe patents Stac has
applied for in the US and maybe other countries. Verify that this is not
the case in your country before using it. This code is a private
development related in no way whatsoever to my employer, written in
Germany where software patents are still considered bogus. This
situation might change any day due to EU law. Linux distributors who
supply this stuff shrink wrapped should reconsider doing this (not only
for isdn_lzscomp, but as well for isdn_bsdcomp, which is likely to
infringe on the infamous Unisys LZW patent) with their law departement.
For more information see
http://www.delphion.com/
Andre Beck
Last modified: Thu Oct 4 13:53:36 MET DST 2001