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Add support for receiving Bter UI frames at lapdm.c 

Similar to support of sending Bter frame, the same rules apply when
receiving them.

Change-Id: If04115884743455c7bf2b2bc5f7e49e74b6ffb60
This commit is contained in:
Andreas Eversberg 2023-05-10 13:23:55 +02:00 committed by laforge
parent 6799741699
commit 0370018eae
1 changed files with 25 additions and 11 deletions
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36
src/gsm/lapdm.c
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@ -57,6 +57,7 @@
#define LAPDm_ADDR_SAPI(addr) (((addr) >> 2) & 0x7)
#define LAPDm_ADDR_CR(addr) (((addr) >> 1) & 0x1)
#define LAPDm_ADDR_EA(addr) ((addr) & 0x1)
#define LAPDm_ADDR_SHORT_L2(addr) ((addr) & 0x3)
/* TS 04.06 Table 3 / Section 3.4.3 */
#define LAPDm_CTRL_I(nr, ns, p) ((((nr) & 0x7) << 5) | (((p) & 0x1) << 4) | (((ns) & 0x7) << 1))
@ -725,15 +726,24 @@ static int l2_ph_data_ind(struct msgb *msg, struct lapdm_entity *le,
if (mctx.link_id & 0x40) {
/* It was received from network on SACCH */
/* If UI on SACCH sent by BTS, lapdm_fmt must be B4 */
if (le->mode == LAPDM_MODE_MS
&& LAPDm_CTRL_is_U(msg->l2h[3])
&& LAPDm_CTRL_U_BITS(msg->l2h[3]) == 0) {
/* A Short L3 header has both bits == 0. */
if (LAPDm_ADDR_SHORT_L2(msg->l2h[2]) == 0) {
mctx.lapdm_fmt = LAPDm_FMT_Bter;
n201 = N201_Bter_SACCH;
sapi = 0;
} else if (le->mode == LAPDM_MODE_MS
&& LAPDm_CTRL_is_U(msg->l2h[3])
&& LAPDm_CTRL_U_BITS(msg->l2h[3]) == 0) {
/* If UI on SACCH sent by BTS, lapdm_fmt must be B4 */
mctx.lapdm_fmt = LAPDm_FMT_B4;
n201 = N201_B4;
/* sapi is found after two-btyte L1 header */
sapi = (msg->l2h[2] >> 2) & 7;
} else {
mctx.lapdm_fmt = LAPDm_FMT_B;
n201 = N201_AB_SACCH;
/* sapi is found after two-btyte L1 header */
sapi = (msg->l2h[2] >> 2) & 7;
}
/* SACCH frames have a two-byte L1 header that
* OsmocomBB L1 doesn't strip */
@ -741,11 +751,17 @@ static int l2_ph_data_ind(struct msgb *msg, struct lapdm_entity *le,
mctx.ta_ind = msg->l2h[1];
msgb_pull(msg, 2);
msg->l2h += 2;
sapi = (msg->l2h[0] >> 2) & 7;
} else {
mctx.lapdm_fmt = LAPDm_FMT_B;
n201 = N201_AB_SDCCH;
sapi = (msg->l2h[0] >> 2) & 7;
/* A Short L3 header has both bits == 0. */
if (LAPDm_ADDR_SHORT_L2(msg->l2h[2]) == 0) {
mctx.lapdm_fmt = LAPDm_FMT_Bter;
n201 = N201_Bter_SDCCH;
sapi = 0;
} else {
mctx.lapdm_fmt = LAPDm_FMT_B;
n201 = N201_AB_SDCCH;
sapi = (msg->l2h[0] >> 2) & 7;
}
}
}
@ -838,9 +854,7 @@ static int l2_ph_data_ind(struct msgb *msg, struct lapdm_entity *le,
rc = lapd_ph_data_ind(msg, &lctx);
break;
case LAPDm_FMT_Bter:
/* FIXME */
msgb_free(msg);
break;
/* fall-through */
case LAPDm_FMT_Bbis:
/* directly pass up to layer3 */
msg->l3h = msg->l2h;