[S] Change in libosmocore[master]: coding: gsm0503_tch_{fr,hr}_encode(): add ability to emit BFI

Attention is currently required from: laforge, fixeria. Hello Jenkins Builder, fixeria, I'd like you to reexamine a change. Please visit https://gerrit.osmocom.org/c/libosmocore/+/33063 to look at the new patch set (#2). Change subject: coding: gsm0503_tch_{fr,hr}_encode(): add ability to emit BFI ...................................................................... coding: gsm0503_tch_{fr,hr}_encode(): add ability to emit BFI Every BTS needs to have some graceful handling for the scenario where it is time to send out a speech frame on TCH DL, but there is no frame to be sent. One possible solution is to transmit dummy FACCH, but this option is unattractive for TCH/HS where FACCH displaces two speech frames rather than one. A more elegant solution is to emit a speech frame with inverted CRC3, causing the MS receiver to declare a BFI condition to its Rx DTX handler. Setting all u(k) bits to 0 is one way to produce such an inverted-CRC speech frame (normal TCH FR/HR CRC3 for an all-zeros frame would be 111), and this method is in fact what sysmoBTS PHY is observed to do. Add the same ability to gsm0503_tch_{fr,hr}_encode() functions, indicated by payload length of 0. Change-Id: Iade3310e16b906efb6892d28f474a0d15204e861 --- M src/coding/gsm0503_coding.c 1 file changed, 43 insertions(+), 1 deletion(-) git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/63/33063/2 -- To view, visit https://gerrit.osmocom.org/c/libosmocore/+/33063 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: libosmocore Gerrit-Branch: master Gerrit-Change-Id: Iade3310e16b906efb6892d28f474a0d15204e861 Gerrit-Change-Number: 33063 Gerrit-PatchSet: 2 Gerrit-Owner: falconia <falcon(a)freecalypso.org> Gerrit-Reviewer: Jenkins Builder Gerrit-Reviewer: fixeria <vyanitskiy(a)sysmocom.de> Gerrit-CC: laforge <laforge(a)osmocom.org> Gerrit-Attention: laforge <laforge(a)osmocom.org> Gerrit-Attention: fixeria <vyanitskiy(a)sysmocom.de> Gerrit-MessageType: newpatchset