9 Nov
2023
9 Nov
'23
8:51 p.m.
fixeria has uploaded this change for review. (
https://gerrit.osmocom.org/c/osmo-bts/+/34991?usp=email )
Change subject: osmo-bts-trx: tx_tch[fh]_fn(): rework generation of dummy FACCH
......................................................................
osmo-bts-trx: tx_tch[fh]_fn(): rework generation of dummy FACCH
Even though it might have a somewhat higher performance impact,
opting for the common code path for FACCH by allocating a msgb
on heap is more favorable for both readability and maintainability.
This choice is preferred over directly calling
gsm0503_tch_fr_encode() and then using a 'goto' statement.
A similar strategy will be adopted in an follow up patch for CSD.
Change-Id: I67cb5c6f4d15149996e17c78a59d66db396da8ff
Related: OS#1572
---
M src/osmo-bts-trx/sched_lchan_tchf.c
M src/osmo-bts-trx/sched_lchan_tchh.c
2 files changed, 61 insertions(+), 28 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/91/34991/1
diff --git a/src/osmo-bts-trx/sched_lchan_tchf.c b/src/osmo-bts-trx/sched_lchan_tchf.c
index 34af8a1..c0dfd47 100644
--- a/src/osmo-bts-trx/sched_lchan_tchf.c
+++ b/src/osmo-bts-trx/sched_lchan_tchf.c
@@ -490,6 +490,19 @@
}
}
+struct msgb *tch_dummy_msgb(size_t size, uint8_t pad)
+{
+ struct msgb *msg;
+
+ msg = msgb_alloc(size, __func__);
+ OSMO_ASSERT(msg != NULL);
+
+ msg->l2h = msgb_put(msg, size);
+ memset(msg->l2h, pad, size);
+
+ return msg;
+}
+
/* obtain a to-be-transmitted TCH/F (Full Traffic Channel) burst */
int tx_tchf_fn(struct l1sched_ts *l1ts, struct trx_dl_burst_req *br)
{
@@ -519,11 +532,6 @@
/* dequeue a TCH and/or a FACCH message to be transmitted */
tch_dl_dequeue(l1ts, br, &msg_tch, &msg_facch);
if (msg_tch == NULL && msg_facch == NULL) {
- static const uint8_t dummy[GSM_MACBLOCK_LEN] = {
- 0x03, 0x03, 0x01, /* TODO: use randomized padding */
- 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b,
- 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b,
- };
int rc;
LOGL1SB(DL1P, LOGL_DEBUG, l1ts, br, "No TCH or FACCH prim for transmit.\n");
@@ -541,13 +549,18 @@
case GSM48_CMODE_SPEECH_EFR:
rc = gsm0503_tch_fr_encode(BUFPOS(bursts_p, 0), NULL, 0, 1);
if (rc == 0)
- break;
+ goto send_burst;
/* fall-through */
+ case GSM48_CMODE_SIGN:
default:
- gsm0503_tch_fr_encode(BUFPOS(bursts_p, 0), dummy, sizeof(dummy), 1);
- chan_state->dl_facch_bursts = 8;
+ /* TODO: use randomized padding */
+ msg_facch = tch_dummy_msgb(GSM_MACBLOCK_LEN, GSM_MACBLOCK_PADDING);
+ /* dummy LAPDm func=UI frame */
+ msg_facch->l2h[0] = 0x03;
+ msg_facch->l2h[1] = 0x03;
+ msg_facch->l2h[2] = 0x01;
+ break;
}
- goto send_burst;
}
/* Unlike SACCH, FACCH has no dedicated slots on the multiframe layout.
diff --git a/src/osmo-bts-trx/sched_lchan_tchh.c b/src/osmo-bts-trx/sched_lchan_tchh.c
index 77309cf..96ee5e8 100644
--- a/src/osmo-bts-trx/sched_lchan_tchh.c
+++ b/src/osmo-bts-trx/sched_lchan_tchh.c
@@ -399,6 +399,8 @@
extern void tch_dl_dequeue(struct l1sched_ts *l1ts, const struct trx_dl_burst_req *br,
struct msgb **msg_tch, struct msgb **msg_facch);
+struct msgb *tch_dummy_msgb(size_t size, uint8_t pad);
+
/* obtain a to-be-transmitted TCH/H (Half Traffic Channel) burst */
int tx_tchh_fn(struct l1sched_ts *l1ts, struct trx_dl_burst_req *br)
{
@@ -445,11 +447,6 @@
/* no message at all, send a dummy L2 frame on FACCH */
if (msg_tch == NULL && msg_facch == NULL) {
- static const uint8_t dummy[GSM_MACBLOCK_LEN] = {
- 0x03, 0x03, 0x01, /* TODO: use randomized padding */
- 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b,
- 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b,
- };
int rc;
LOGL1SB(DL1P, LOGL_INFO, l1ts, br, "No TCH or FACCH prim for transmit.\n");
@@ -462,25 +459,30 @@
* and decide what is the correct BTS Tx behavior for frame
* gaps in TCH/AHS. See OS#6049.
*/
- if (tch_mode == GSM48_CMODE_SPEECH_V1) {
+ switch (tch_mode) {
+ case GSM48_CMODE_SPEECH_V1:
rc = gsm0503_tch_hr_encode(BUFPOS(bursts_p, 0), NULL, 0);
if (rc == 0)
goto send_burst;
- }
+ /* fall-through */
+ case GSM48_CMODE_SIGN:
+ default:
+ /* FACCH/H can only be scheduled at specific TDMA offset */
+ if (!sched_tchh_dl_facch_map[br->fn % 26]) {
+ /* FACCH/H is not allowed, send half-filled bursts with even numbered
+ * bits contaning 232 encoded bits of the previous L2 frame, and 232
+ * odd numbered bits all set to 0. */
+ goto send_burst;
+ }
- /* FACCH/H can only be scheduled at specific TDMA offset */
- if (!sched_tchh_dl_facch_map[br->fn % 26]) {
- /* FACCH/H is not allowed, send half-filled bursts with even numbered
- * bits contaning 232 encoded bits of the previous L2 frame, and 232
- * odd numbered bits all set to 0. */
- goto send_burst;
+ /* TODO: use randomized padding */
+ msg_facch = tch_dummy_msgb(GSM_MACBLOCK_LEN, GSM_MACBLOCK_PADDING);
+ /* dummy LAPDm func=UI frame */
+ msg_facch->l2h[0] = 0x03;
+ msg_facch->l2h[1] = 0x03;
+ msg_facch->l2h[2] = 0x01;
+ break;
}
-
- gsm0503_tch_hr_encode(BUFPOS(bursts_p, 0), dummy, sizeof(dummy));
- if (chan_state->rsl_cmode != RSL_CMOD_SPD_DATA)
- chan_state->dl_ongoing_facch = 1;
- chan_state->dl_facch_bursts = 6;
- goto send_burst;
}
/* Unlike SACCH, FACCH has no dedicated slots on the multiframe layout.
--
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Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Change-Id: I67cb5c6f4d15149996e17c78a59d66db396da8ff
Gerrit-Change-Number: 34991
Gerrit-PatchSet: 1
Gerrit-Owner: fixeria <vyanitskiy(a)sysmocom.de>
Gerrit-MessageType: newchange