L1 and L2 now pass UI frames like BCCH and CCCH downlink up into
L3, which detects an IMMediate ASSignment command and instructs
the L1 to switch to SDCCH/4.
From this point on, SDCCH/4 and SACCH4/C messages end up in our
L2 LAPDm implementation and are forwarded to L3.
Using the following changes, it is now possible to receive the PCH and AGCH
messages in the PC-side layer3, as well as trigger RACH sending inside the phone
from the PC:
* merge l1_dedic_mode_data_ind, l1_dedic_mode_data_req and l1_ccch_info_ind into l1_data_ind
* add partial LAPDm implementation (layer2/src/lapdm.c)
* introduce RSLms between LAPDm and L3 (layer2/src/osmocom_rslms.c)
* use new layer1 header field of msgb
* tx_ph_rach_req() and tx_ph_data_req() to send data from PC to target
* implement DEDIC_MODE_DATA_REQ on firmware side
This enables the layer2 to identify on which channel
(BCCH/CCCH/SDCCH/TCH/...) the respective message was received.
* Encode MFrame Task Number + SACCH info in 'p3' parameter
* Generate channel number and link identifier
* Decode channel number in layer2 program
libosmocore is a new library that has been created out of OpenBSC,
and it provides almost everything we've tried here with libosmocom.
The only remaining part is the 'debug' part
Harald Welte
Erik Ekman