PCU sends invalid block number to L1

Harald Welte laforge at gnumonks.org
Mon May 2 16:48:13 UTC 2016

Hi Minh,

first of all, thanks for helping out in terms of OsmoPCU/OsmoBTS bug
hunting, it is much appreciated.  It is a collaborative project, after
all :)

On Mon, May 02, 2016 at 09:32:12AM -0400, Minh-Quang Nguyen wrote:
> After an investigation, we observe that the 'pcu_rx_rts_req' function
> in pcu_l1_if.cpp receives invalid block number from BTS.
> Looking at the BTS side, the calculation of L1SAP_FN2PTCCHBLOCK
> defined as '#define L1SAP_FN2PTCCHBLOCK(fn) ((fn / 52) & 7)' does not
> seem to be valid for expected PTCCH block numbers B0, B1,B2,B3 defined
> in Table 6 in TS 05.02 version 8.11.0.
> What do you think about re-define the calculation of the L1SAP_FN2PTCCHBLOCK?  

If you find the existing calculation is not agreeing with the
specification (I'd have to re-read the spec, but I trust you when you
say that), I would appreciate if you could send a patch (or patch
series) that changes it to be within the spec.  If the calculation is
more complex, better use a separate function than the simplistic macro.

Thanks in advance!

- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
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