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Harald Welte laforge at gnumonks.orgHi Gerard,
sorry for the delayed response, sometimes there are simply too many
tasks and mails to handle :/
On Fri, May 19, 2017 at 10:28:56PM -0700, Gerard Lawrence Pinto wrote:
> Congrats on OsmoCon 2017!
thanks!
> I have been working with OsmocomBB, osmo-sim-auth, mncc-python
> projects in Osmocom.
great. The important part is now to make sure those changes don't live
somewhere out there but to think how they can be merged mainline!
> To begin with I have committed:
> I) MNCC with OsmocomBB - *https://github.com/GerardPinto/call-control-mncc-sap
> <https://github.com/GerardPinto/call-control-mncc-sap>* (Has both
> implementations in Python and C + Tested voice with gsm-fr with gsm audio
> file - works great).
> - Some of which can be committed to mncc-python? (In order to support
> MNCC with OsmocomBB too) Although, Harald told me it was built for OpenNITB
> - I'm not sure, the relevance of this contribution to this repo?
MNCC should be virtually the same, whether on OsmocomBB or on OsmoNITB
(or now OsmoMSC). Let's avoid having different implementations and
different repositories. At least regarding the python code, please
submit your changes to mncc-python
We generally try to avoid fragmentation of code but want to have one
implementation of a given functionality within the project. So what's
needed is the knowledge of what exactly is missing or needs
modification/improvement in mncc-python, not another implementation with
unclear status on what are advantages/disadvantages of either of them.
So I suggest we move the existing mncc-python repository into gerrit,
and then you can submit whatever you think is missing in mncc-python?
How does that sound?
A general suggestion (independent of Osmocom): Please always put license
information in your code. Otherwise it is not clear if anyone is able
to use it (and under what terms).
> *Issues faced*: File: l23api.c | function: l1ctl_rx_traffic_req()
> 264 bits (33 bytes) of voice codec are interleaved into 456 bits. The DAC,
> ciphering/deciphering , RF etc. work on 114 bits at a time so, 114 x 4 =
> 456.
> So Layer23 sends 4 - 114 bits into the queue to Layer1 in function =>
> l1ctl_rx_traffic_req
> *Code*: num = l1a_txq_msgb_count(&l1s.tx_queue[L1S_CHAN_TRAFFIC])
> if num > 4 dropping traffic frame. (114 x 4)
> The code above indicates if queue has any (114 x 4) bits drop the incoming
> voice request.
Well, GSM is a TDMA system and everything has to happen with regard to
the TDMA clock as defined by the BTS (clock master). So you cannot
send voice frames faster than the TDMA clock is transmitting them.
> *My Question is*: If I happened to send voice packets 33 bytes really fast.
> There should be some kind of buffer rather than a check (Code) and drop
> frame? - OR this case can never happen?
The way how to properly solve this (normally) is that Layer1 is sending
something like "ready to send (RTS) indications" to Layer2, and Layer2
then knows it has to send another frame. This way, the timing is
defined by L1. However, as there is latency between L1 and L2 (serial
line, operating system scheduling, ...) there actually needs to be a bit
of a buffer or an "advancement" of the RTS indications to compensate for
that.
L1CTL doesn't have this so far, but it would of course be appreciated if
somebody would make it more robust and contribute related patches.
Please also keep future osmocom-bb related questions to the
baseband-devel list, thanks!
> II) osmo-sim-auth with added other SIM related API's (still needs code
> clean up, SIM response check, code re-usable, README.md etc,)
> * https://github.com/GerardPinto/osmo-sim-auth
> <https://github.com/GerardPinto/osmo-sim-auth> *
> - I did check out PySIM (I think I can add some code to the existing
> repository, with your permission).
If you work on existing code, then please properly clone the original
repository and then add your patches on top of it. That way one can
browse the commit log and clearly look ad individual patches. I'm
unable to figure out what you did by looking at your repository, as you
appear to have imported an unknown version of osmo-sim-auth without
cloning the original repository and keeping history.
> Could you please let me know if my osmo-sim-auth repo? If it is correct to
> combine with PySIM, with the changes done below?
I'm happy to review it once there is a repo based on the original one
with change sets to review. We can also move osmo-sim-auth to gerrit so
you can submit your patches there. But in order to do that, you would
also have to do a proper clone of the original repo and implement your
changes as commits on top.
Regards,
Harald
--
- Harald Welte <laforge at gnumonks.org> http://laforge.gnumonks.org/
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