[PATCH] osmo-pcu[master]: Fix issues in URBB generation in EGPRS PUAN

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prasadkg gerrit-no-reply at lists.osmocom.org
Thu Aug 11 06:07:56 UTC 2016 

Hello Jenkins Builder, Holger Freyther,

I'd like you to reexamine a change.  Please visit

    https://gerrit.osmocom.org/412

to look at the new patch set (#2).

Fix issues in URBB generation in EGPRS PUAN

Below issue in uncompresed bitmap generation is addressed
1. Corrected the number of bits that is included in URBB
2. If length is not present, 0s are coded as remaining bits
Along with this, code is restructured to enable addition of
compression support

Change-Id: Ie5c25b6ee30f2f1b613e923c234b03a6ffe12ae2
---
M src/encoding.cpp
M tests/tbf/TbfTest.err
2 files changed, 44 insertions(+), 35 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/osmo-pcu refs/changes/12/412/2

diff --git a/src/encoding.cpp b/src/encoding.cpp
index 63049ac..f372424 100644
--- a/src/encoding.cpp
+++ b/src/encoding.cpp
@@ -541,18 +541,21 @@
 };
 
 static void write_packet_ack_nack_desc_egprs(
-	struct gprs_rlcmac_bts *bts, bitvec * dest, unsigned& wp,
+	struct gprs_rlcmac_bts *bts, bitvec *dest, unsigned& wp,
 	gprs_rlc_ul_window *window, bool is_final)
 {
 	int urbb_len = 0;
-	int crbb_len = 0;
 	int len;
 	bool bow = true;
 	bool eow = true;
 	int ssn = window->mod_sns(window->v_q() + 1);
 	int num_blocks = window->mod_sns(window->v_r() - window->v_q());
 	int esn_crbb = window->mod_sns(ssn - 1);
-	int rest_bits = dest->data_len * 8 - wp;
+	/* Bit 0 at the end is mandatory Table 11.2.28.1 in 44.060 */
+	int rest_bits = dest->data_len * 8 - wp - 1;
+	int is_compressed = 0;
+	bool len_coded = true;
+	uint8_t i;
 
 	if (num_blocks > 0)
 		/* V(Q) is NACK and omitted -> SSN = V(Q) + 1 */
@@ -560,32 +563,31 @@
 
 	if (num_blocks > window->ws())
 		num_blocks = window->ws();
+	/* TODO Compression support */
+	if (is_compressed == 0) {
+		/* Union bit takes 1 bit */
+		/* Other fields in descr for uncompresed bitmap takes 15 bits*/
 
-	if (num_blocks > rest_bits) {
-		eow = false;
-		urbb_len = rest_bits;
-		/* TODO: use compression, start encoding bits and stop when the
-		 * space is exhausted. Use the first combination that encodes
-		 * all bits. If there is none, use the combination that encodes
-		 * the largest number of bits (e.g. by setting num_blocks to the
-		 * max and repeating the construction).
-		 */
-	} else if (num_blocks > rest_bits - 9) {
-		/* union bit and length field take 9 bits */
-		eow = false;
-		urbb_len = rest_bits - 9;
-		/* TODO: use compression (see above) */
+		if (num_blocks > rest_bits - 15 - 1) {
+			eow = false;
+			urbb_len = rest_bits - 15 - 1;
+			len_coded = false;
+		} else if (num_blocks == rest_bits - 15 - 1) {
+			urbb_len = rest_bits - 15 - 1;
+			len_coded = false;
+		/* Union bit takes 1 bit length field takes 8 bits*/
+		} else if (num_blocks > rest_bits - 15 - 9) {
+			eow = false;
+			urbb_len = rest_bits - 15 - 9;
+		} else
+			urbb_len = num_blocks;
+		len = urbb_len + 15;
+	} else {
+		/* TODO Compressed bitmap */
 	}
 
-	if (urbb_len + crbb_len == rest_bits)
-		len = -1;
-	else if (crbb_len == 0)
-		len = urbb_len + 15;
-	else
-		len = urbb_len + crbb_len + 23;
-
 	/* EGPRS Ack/Nack Description IE */
-	if (len < 0) {
+	if (len_coded == false) {
 		bitvec_write_field(dest, wp, 0, 1); // 0: don't have length
 	} else {
 		bitvec_write_field(dest, wp, 1, 1); // 1: have length
@@ -596,21 +598,28 @@
 	bitvec_write_field(dest, wp, bow, 1); // BEGINNING_OF_WINDOW
 	bitvec_write_field(dest, wp, eow, 1); // END_OF_WINDOW
 	bitvec_write_field(dest, wp, ssn, 11); // STARTING_SEQUENCE_NUMBER
-	bitvec_write_field(dest, wp, 0, 1); // 0: don't have CRBB
-
-	/* TODO: Add CRBB support */
-
+	if (is_compressed) {
+		/* TODO Add CRBB support */
+	} else
+		bitvec_write_field(dest, wp, 0, 1); // CRBB_Exist
 	LOGP(DRLCMACUL, LOGL_DEBUG,
-		" - EGPRS URBB, len = %d, SSN = %d, ESN_CRBB = %d, "
+		"EGPRS URBB, urbb len = %d, SSN = %d, ESN_CRBB = %d, "
+		"len present = %s,desc len = %d, "
 		"SNS = %d, WS = %d, V(Q) = %d, V(R) = %d%s%s\n",
-		urbb_len, ssn, esn_crbb,
+		urbb_len, ssn, esn_crbb, len_coded ? "yes" : "No", len,
 		window->sns(), window->ws(), window->v_q(), window->v_r(),
 		bow ? ", BOW" : "", eow ? ", EOW" : "");
-	for (int i = urbb_len; i > 0; i--) {
+
+	for (i = urbb_len; i > 0; i--) {
 		/* Set bit at the appropriate position (see 3GPP TS 04.60 12.3.1) */
 		bool is_ack = window->m_v_n.is_received(esn_crbb + i);
 		bitvec_write_field(dest, wp, is_ack, 1);
 	}
+	/* If len is not coded, set remaining bits as 0 */
+	if (len_coded == false) {
+		for (i = wp; i < dest->data_len*8; i++)
+			bitvec_write_field(dest, wp, 0, 1);
+	}
 }
 
 static void write_packet_uplink_ack_egprs(
diff --git a/tests/tbf/TbfTest.err b/tests/tbf/TbfTest.err
index e5c0a78..cd56402 100644
--- a/tests/tbf/TbfTest.err
+++ b/tests/tbf/TbfTest.err
@@ -6028,10 +6028,10 @@
 - Raising V(R) to 65
 Received RTS for PDCH: TRX=0 TS=7 FN=2654275 block_nr=9 scheduling USF=0 for required uplink resource of UL TFI=0
 Encoding Ack/Nack for TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW EGPRS) (final=0)
- - EGPRS URBB, len = 0, SSN = 2, ESN_CRBB = 1, SNS = 2048, WS = 64, V(Q) = 1, V(R) = 65, BOW, EOW
-Uplink Ack/Nack bit count 98, max 184, message = 40 24 01 23 3e 24 46 68 90 87 b0 04 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 
+EGPRS URBB, urbb len = 63, SSN = 2, ESN_CRBB = 1, len present = yes,desc len = 78, SNS = 2048, WS = 64, V(Q) = 1, V(R) = 65, BOW, EOW
+Uplink Ack/Nack bit count 161, max 184, message = 40 24 01 23 3e 24 46 68 90 a7 30 04 80 00 00 2a aa aa aa aa 2b 2b 2b 
 Scheduling control message at RTS for TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW EGPRS) (TRX=0, TS=7)
-Sending data request: trx=0 ts=7 sapi=5 arfcn=0 fn=2654275 block=9 data=40 24 01 23 3e 24 46 68 90 87 b0 04 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 
+Sending data request: trx=0 ts=7 sapi=5 arfcn=0 fn=2654275 block=9 data=40 24 01 23 3e 24 46 68 90 a7 30 04 80 00 00 2a aa aa aa aa 2b 2b 2b 
 Got 'TBF(TFI=0 TLLI=0xf1223344 DIR=UL STATE=FLOW EGPRS)', TA=7
 Got MS: TLLI = 0xf1223344, TA = 7
 ********** TBF starts here **********

-- 
To view, visit https://gerrit.osmocom.org/412
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Ie5c25b6ee30f2f1b613e923c234b03a6ffe12ae2
Gerrit-PatchSet: 2
Gerrit-Project: osmo-pcu
Gerrit-Branch: master
Gerrit-Owner: prasadkg <Prasad.Kaup at radisys.com>
Gerrit-Reviewer: Holger Freyther <holger at freyther.de>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: prasadkg <Prasad.Kaup at radisys.com>

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