This commit follows a similar approach to Change-Id
I588eb576b2703262f4ab9566ec362920d8390cfd, this time targeting the SNDCP
layer, creating a new library for it.
This new library depends on headers from libosmo-gprs-llc since the
SNDCP spec takes the interface towards lower interfaces from same
llc_prim. It doesn't really call any API from the libosmo-gprs-llc
library to dispatch the primitive, that's left for the application, so
that it can be reused against other implementations.
Most of the SNDCP data structures and APIs are kept private and used
only internally. The Higher/lower layers are expected to interact with
it through the sndcp_prim API.
This commit also implements some of the code paths of the public API by
means on importing SNDCP code from osmo-sgsn.git commit
The import of code cannot be done in a separate commit since existing code
in osmo-sgsn.git is low quality and has tons of layer violations in all
Hence, this commit aims at being an initial point of having some working
SNDCP stack by means of a few unit tests, but by no means aims to be a
total working implementation. Some code paths are missing; bugs are
expected at this point.