Harald Welte has submitted this change and it was merged.
Change subject: WIP: Work towards a more real DL TBF receiver implementation
......................................................................
WIP: Work towards a more real DL TBF receiver implementation
Change-Id: I300312734d99f2b8a406f39e04b4f738940f7579
---
M library/RLCMAC_Types.ttcn
M pcu/GPRS_TBF.ttcn
2 files changed, 161 insertions(+), 17 deletions(-)
Approvals:
Harald Welte: Looks good to me, approved
Jenkins Builder: Verified
diff --git a/library/RLCMAC_Types.ttcn b/library/RLCMAC_Types.ttcn
index 3ae1203..c946594 100644
--- a/library/RLCMAC_Types.ttcn
+++ b/library/RLCMAC_Types.ttcn
@@ -113,7 +113,14 @@
boolean e
} with {
variant (e) "FIELDLENGTH(1)"
+ encode "RAW"
};
+
+ external function enc_LlcBlockHdr(in LlcBlockHdr si) return octetstring
+ with { extension "prototype(convert) encode(RAW)" };
+ external function dec_LlcBlockHdr(in octetstring stream) return
LlcBlockHdr
+ with { extension "prototype(convert) decode(RAW)" };
+
type record LlcBlock {
/* Header is only present if LI field was present */
LlcBlockHdr hdr optional,
diff --git a/pcu/GPRS_TBF.ttcn b/pcu/GPRS_TBF.ttcn
index a35c780..3e8658e 100644
--- a/pcu/GPRS_TBF.ttcn
+++ b/pcu/GPRS_TBF.ttcn
@@ -18,8 +18,25 @@
import from LLC_Types all;
import from GPRS_Context all;
-/* input parameters into TBF (mostly mode/cs + LLC PDUs */
+private const integer RLC_GPRS_SNS := 128;
+private const integer RLC_GPRS_WS := 64;
+private const integer RLC_EGPRS_MIN_WS := 64;
+private const integer RLC_EGPRS_MAX_WS := 1024;
+private const integer RLC_EGPRS_SNS := 2048;
+private const integer RLC_EGPRS_MAX_BSN_DELTA := 512;
+private const integer RLC_MAX_SNS := RLC_EGPRS_SNS;
+private const integer RLC_MAX_WS := RLC_EGPRS_MAX_WS;
+private const integer RLC_MAX_LEN := 74 /* MCS-9 data unit */
+private const integer sns_half := (RLC_MAX_SNS / 2);
+private const integer mod_sns_half := (RLC_MAX_SNS / 2) - 1;
+
+
+/***********************************************************************
+ * Uplink TBF handling
+ ***********************************************************************/
+
+/* input parameters into TBF (mostly mode/cs + LLC PDUs */
type record UlTbfPars {
/* Acknowledged mode (true) or unacknowledged (false) */
boolean ack_mode,
@@ -45,22 +62,6 @@
ep.v_a := 0;
ep.v_b := int2bit(0, 128); /* FIXME: EGPRS 2048 bits length */
}
-
-type record RlcEndpointRx {
- /* receive state variable V(R) (9.1.5): BSN one higher than highest BSN
yet received (mod SNS) */
- integer v_r,
- /* receive window state variable V(Q) (9.1.6): Lowest BSN not yet
received (mod SNS) */
- integer v_q,
- /* receive state array V(N) (9.1.7) */
- bitstring v_n
-}
-
-private function f_RlcEndpointRx_init(inout RlcEndpointRx ep) {
- ep.v_r := 0;
- ep.v_q := 0;
- ep.v_n := int2bit(0, 128); /* FIXME: EGPRS 2048 bits length */
-}
-
type record UlTbfState {
/* "const" input state with TBF Data */
@@ -360,6 +361,142 @@
}
}
+/***********************************************************************
+ * Downlink TBF handling
+ ***********************************************************************/
+
+type record RlcEndpointRx {
+ /* receive state variable V(R) (9.1.5): BSN one higher than highest BSN
yet received (mod SNS) */
+ integer v_r,
+ /* receive window state variable V(Q) (9.1.6): Lowest BSN not yet
received (mod SNS) */
+ integer v_q,
+ /* receive state array V(N) (9.1.7) */
+ bitstring v_n
+}
+
+private function f_RlcEndpointRx_init(inout RlcEndpointRx ep) {
+ ep.v_r := 0;
+ ep.v_q := 0;
+ ep.v_n := int2bit(0, 128); /* FIXME: EGPRS 2048 bits length */
+}
+
+type record DlTbfPars {
+ /* Acknowledged mode (true) or unacknowledged (false) */
+ boolean ack_mode,
+ /* Coding Scheme for transmission, determines block size */
+ GprsCodingScheme initial_cs,
+ /* Sequence Number Space */
+ integer sns,
+ /* Window Size */
+ integer ws
+}
+
+type record DlTbfState {
+ /* "const" input state with TBF Data */
+ DlTbfPars tbf,
+ uint8_t num_ts,
+
+ RlcEndpointRx er,
+
+ integer tfi,
+
+ /* list of abstract/decoded RLC PDUs */
+ record of RlcmacDlBlock rlc_received
+}
+
+function f_dl_tbf_mod_sns(DlTbfState ds, integer val) return integer
+{
+ return (val mod ds.tbf.sns);
+}
+
+function f_dl_tbf_is_in_window(integer bsn) return boolean {
+ setverdict(fail, "pleaes implement me");
+ self.stop;
+}
+
+function f_dl_tbf_is_received(inout DlTbfState ds, integer bsn) return boolean
{
+ var integer offset_v_r;
+
+ if (not f_dl_tbf_is_in_window(bsn)) {
+ return false;
+ }
+
+ /* offset to the end of the received window */
+ offset_v_r := f_dl_tbf_mod_sns(ds, ds.er.v_r - 1 - bsn);
+ if (not (offset_v_r < ds.tbf.ws)) {
+ return false;
+ }
+
+ if (ds.er.v_n[bsn mod sns_half] == '1'B) {
+ return true;
+ }
+
+ return false;
+}
+
+function f_dl_tbf_mark_received(inout DlTbfState ds, integer bsn) {
+ ds.er.v_n[bsn mod sns_half] := '1'B;
+ f_dl_tbf_raise_v_r(ds, bsn);
+}
+
+/* Raise V(Q) if possible */
+function f_dl_tbf_raise_v_q(inout DlTbfState ds, integer bsn) return integer {
+ var integer count := 0;
+ while (ds.er.v_q != ds.er.v_r) {
+ var integer v_q_old := ds.er.v_q;
+ if (not f_dl_tbf_is_received(ds, v_q_old)) {
+ break;
+ }
+ ds.er.v_q := f_dl_tbf_mod_sns(ds, ds.er.v_q + 1)
+ log("RLCMAC: Taking block ", v_q_old, " out, raising V(Q) to ",
ds.er.v_q);
+ count := count+1;
+ }
+ return count;
+}
+
+function f_dl_tbf_raise_v_r(inout DlTbfState ds, integer bsn) {
+ var integer offset_v_r := f_dl_tbf_mod_sns(ds, bsn + 1 - ds.er.v_r);
+ if (offset_v_r < (ds.tbf.sns / 2)) {
+ for (var integer i := offset_v_r; i > 0; i := i-1) {
+ /* mark as missing */
+ ds.er.v_n[bsn mod sns_half] := '0'B;
+ //raise_v_r_to(1);
+ }
+ log("RLCMAC: Raising V(R) to ", ds.er.v_r);
+ }
+}
+
+/* process the actual data and update TbfState */
+function f_dl_tbf_process_dl_data(inout DlTbfState ds, RlcmacDlDataBlock db) {
+ var integer bsn := db.mac_hdr.hdr_ext.bsn;
+ if (db.mac_hdr.hdr_ext.tfi != ds.tfi) {
+ setverdict(fail, "Unexpected TFI of DL Data Block ", db);
+ self.stop;
+ }
+ f_dl_tbf_mark_received(ds, bsn);
+ if (ds.tbf.ack_mode) {
+ /* In RLC acknowledged mode, the receive window is defined by
the receive window
+ * state variable V(Q) in the following inequality[ V(Q) ≤ BSN
< V(Q)+ WS ] modulo
+ * SNS */
+ if (bsn < ds.er.v_q or bsn > ds.er.v_q + ds.tbf.ws) {
+ setverdict(fail, "Unexpected BSN outside of window ",
bsn);
+ self.stop;
+ }
+
+ /* In RLC acknowledged mode, the value of V(Q) shall be updated
when the RLC
+ * receiver receives the RLC data block whose BSN is equal to
V(Q). The value of
+ * V(Q) shall then be set to the BSN value of the next RLC data
block in the receive
+ * window (modulo SNS) that has not yet been received, or it
shall be set to V(R) if
+ * all RLC data blocks in the receive window have been received
*/
+ f_dl_tbf_mark_received(ds, bsn);
+ } else {
+ /* In RLC unacknowledged mode, if [V(R) - V(Q)] modulo SNS > WS
after updating V(R),
+ * then V(Q) is set to [V(R) - WS] modulo SNS. */
+ /* FIXME */
+ }
+
+}
+
}
--
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Gerrit-MessageType: merged
Gerrit-Change-Id: I300312734d99f2b8a406f39e04b4f738940f7579
Gerrit-PatchSet: 3
Gerrit-Project: osmo-ttcn3-hacks
Gerrit-Branch: master
Gerrit-Owner: Harald Welte <lafo...@gnumonks.org>
Gerrit-Reviewer: Harald Welte <lafo...@gnumonks.org>
Gerrit-Reviewer: Jenkins Builder
