Modify EGPRS DL TBF flow to support SPB

Modify the EGPRS DL TBF flow to support Split block during
Retx. This patch will also Upgrade the test suite with test cases
to validate the EGPRS Downlink SPB for Retransmission

Scenarios like MCS6->MCS3, MCS4->MCS1, MCS5->MCS2, MCS9->MCS3
MCS7->MCS2, MCS8->MCS3 have been simulated and Integration tested
in NuRAN 1.0 hardware thoroughly.

Change-Id: I242afdd8ae7622dec8593b26382ad66bad5b9516

1 files changed, 183 insertions, 33 deletions

diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index 07a747a4..a24cc21b 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -375,21 +375,28 @@ int gprs_rlcmac_dl_tbf::take_next_bsn(uint32_t fn,
 			return -1;
 
 		if (is_egprs_enabled()) {
+			/* Table 8.1.1.2 and Table 8.1.1.1 of 44.060 */
 			m_rlc.block(bsn)->cs_current_trans =
-			GprsCodingScheme::get_retx_mcs(
-			m_rlc.block(bsn)->cs_last, ms()->current_cs_dl());
+				GprsCodingScheme::get_retx_mcs(
+					m_rlc.block(bsn)->cs_init,
+					ms()->current_cs_dl(),
+					bts->bts_data()->dl_arq_type);
 
 			LOGP(DRLCMACDL, LOGL_DEBUG,
-			"- current_cs_dl(%d) demanded_mcs(%d) cs_trans(%d)\n",
-			m_rlc.block(bsn)->cs_last.to_num(),
-			ms()->current_cs_dl().to_num(),
-			m_rlc.block(bsn)->cs_current_trans.to_num());
+				"- initial_cs_dl(%d) last_mcs(%d)"
+				" demanded_mcs(%d) cs_trans(%d)"
+				" arq_type(%d) bsn(%d)\n",
+				m_rlc.block(bsn)->cs_init.to_num(),
+				m_rlc.block(bsn)->cs_last.to_num(),
+				ms()->current_cs_dl().to_num(),
+				m_rlc.block(bsn)->cs_current_trans.to_num(),
+				bts->bts_data()->dl_arq_type, bsn);
 
 			/* TODO: Need to remove this check when MCS-8 -> MCS-6
 			 * transistion is handled.
 			 * Refer commit be881c028fc4da00c4046ecd9296727975c206a3
 			 */
-			if (m_rlc.block(bsn)->cs_last == GprsCodingScheme::MCS8)
+			if (m_rlc.block(bsn)->cs_init == GprsCodingScheme::MCS8)
 				m_rlc.block(bsn)->cs_current_trans =
 					GprsCodingScheme::MCS8;
 		} else
@@ -523,6 +530,11 @@ int gprs_rlcmac_dl_tbf::create_new_bsn(const uint32_t fn, GprsCodingScheme cs)
 	data = rlc_data->prepare(block_data_len);
 	rlc_data->cs_last = cs;
 	rlc_data->cs_current_trans = cs;
+
+	/* Initialise the variable related to DL SPB */
+	rlc_data->spb_status.block_status_dl = EGPRS_RESEG_DL_DEFAULT;
+	rlc_data->cs_init = cs;
+
 	rlc_data->len = block_data_len;
 
 	rdbi = &(rlc_data->block_info);
@@ -616,7 +628,8 @@ struct msgb *gprs_rlcmac_dl_tbf::create_dl_acked_block(
 	unsigned num_bsns;
 	enum egprs_puncturing_values punct[ARRAY_SIZE(rlc.block_info)];
 	bool need_padding = false;
-
+	enum egprs_rlcmac_dl_spb spb = EGPRS_RLCMAC_DL_NO_RETX;
+	unsigned int spb_status = get_egprs_dl_spb_status(index);
 	/*
 	 * TODO: This is an experimental work-around to put 2 BSN into
 	 * MSC-7 to MCS-9 encoded messages. It just sends the same BSN
@@ -626,6 +639,7 @@ struct msgb *gprs_rlcmac_dl_tbf::create_dl_acked_block(
 	 * the current limit.
 	 */
 	cs = m_rlc.block(index)->cs_current_trans;
+	GprsCodingScheme &cs_init = m_rlc.block(index)->cs_init;
 	bsns[0] = index;
 	num_bsns = 1;
 
@@ -634,7 +648,17 @@ struct msgb *gprs_rlcmac_dl_tbf::create_dl_acked_block(
 		num_bsns += 1;
 	}
 
-	if (num_bsns == 1) {
+	/*
+	 * if the intial mcs is 8 and retransmission mcs is either 6 or 3
+	 * we have to include the padding of 6 octets in first segment
+	 */
+	if ((GprsCodingScheme::Scheme(cs_init) == GprsCodingScheme::MCS8) &&
+		(GprsCodingScheme::Scheme(cs) == GprsCodingScheme::MCS6 ||
+		GprsCodingScheme::Scheme(cs) == GprsCodingScheme::MCS3)) {
+		if (spb_status == EGPRS_RESEG_DL_DEFAULT ||
+			spb_status == EGPRS_RESEG_SECOND_SEG_SENT)
+			need_padding  = true;
+	} else if (num_bsns == 1) {
 		/* TODO: remove the conditional when MCS-6 padding isn't
 		 * failing to be decoded by MEs anymore */
 		/* TODO: support of MCS-8 -> MCS-6 transition should be
@@ -646,7 +670,14 @@ struct msgb *gprs_rlcmac_dl_tbf::create_dl_acked_block(
 			cs.decToSingleBlock(&need_padding);
 	}
 
-	gprs_rlc_data_info_init_dl(&rlc, cs, need_padding);
+	spb = get_egprs_dl_spb(index);
+
+	LOGP(DRLCMACDL, LOGL_DEBUG, "- need_padding %d spb_status %d spb %d"
+			"(BSN1 %d BSN2 %d)\n",
+			need_padding,
+			spb_status, spb, index, index2);
+
+	gprs_rlc_data_info_init_dl(&rlc, cs, need_padding, spb);
 
 	rlc.usf = 7; /* will be set at scheduler */
 	rlc.pr = 0; /* FIXME: power reduction */
@@ -665,10 +696,9 @@ struct msgb *gprs_rlcmac_dl_tbf::create_dl_acked_block(
 		data_block_idx++)
 	{
 		int bsn;
-		GprsCodingScheme cs_enc;
 		uint8_t *block_data;
 		gprs_rlc_data_block_info *rdbi, *block_info;
-		enum egprs_puncturing_values punct_scheme;
+		enum egprs_rlc_dl_reseg_bsn_state reseg_status;
 
 		/* Check if there are more blocks than BSNs */
 		if (data_block_idx < num_bsns)
@@ -676,38 +706,43 @@ struct msgb *gprs_rlcmac_dl_tbf::create_dl_acked_block(
 		else
 			bsn = bsns[0];
 
-		cs_enc = m_rlc.block(bsn)->cs_current_trans;
-		/* get data and header from current block */
-		block_data = m_rlc.block(bsn)->block;
-
 		/* Get current puncturing scheme from block */
-		punct_scheme = gprs_get_punct_scheme(
+
+		m_rlc.block(bsn)->next_ps = gprs_get_punct_scheme(
 			m_rlc.block(bsn)->next_ps,
-			m_rlc.block(bsn)->cs_last, cs);
+			m_rlc.block(bsn)->cs_last, cs, spb);
 
 		if (cs.isEgprs()) {
-			OSMO_ASSERT(punct_scheme >= EGPRS_PS_1);
-			OSMO_ASSERT(punct_scheme <= EGPRS_PS_3);
+			OSMO_ASSERT(m_rlc.block(bsn)->next_ps >= EGPRS_PS_1);
+			OSMO_ASSERT(m_rlc.block(bsn)->next_ps <= EGPRS_PS_3);
 		}
-		punct[data_block_idx] = punct_scheme;
+		punct[data_block_idx] = m_rlc.block(bsn)->next_ps;
 
 		rdbi = &rlc.block_info[data_block_idx];
 		block_info = &m_rlc.block(bsn)->block_info;
 
-		if(rdbi->data_len != m_rlc.block(bsn)->len) {
-			LOGP(DRLCMACDL, LOGL_ERROR,
-				"ERROR: Expected len = %d for %s instead of "
-				"%d in data unit %d (BSN %d, %s)\n",
-				rdbi->data_len, cs.name(), m_rlc.block(bsn)->len,
-				data_block_idx, bsn, cs_enc.name());
-			OSMO_ASSERT(rdbi->data_len == m_rlc.block(bsn)->len);
-		}
+		/*
+		 * get data and header from current block
+		 * function returns the reseg status
+		 */
+		reseg_status = egprs_dl_get_data(bsn, &block_data);
+		m_rlc.block(bsn)->spb_status.block_status_dl = reseg_status;
 
-		/* TODO: Need to handle 2 same bsns
-		 * in header type 1
+		/*
+		 * If it is first segment of the split block set the state of
+		 * bsn to nacked. If it is the first segment dont update the
+		 * next ps value of bsn. since next segment also needs same cps
 		 */
-		gprs_update_punct_scheme(&m_rlc.block(bsn)->next_ps,
-					cs);
+		if (spb == EGPRS_RLCMAC_DL_FIRST_SEG)
+			m_window.m_v_b.mark_nacked(bsn);
+		else {
+			/*
+			 * TODO: Need to handle 2 same bsns
+			 * in header type 1
+			 */
+			gprs_update_punct_scheme(&m_rlc.block(bsn)->next_ps,
+						cs);
+		}
 
 		m_rlc.block(bsn)->cs_last = cs;
 		rdbi->e   = block_info->e;
@@ -1169,3 +1204,118 @@ bool gprs_rlcmac_dl_tbf::keep_open(unsigned fn) const
 	keep_time_frames = msecs_to_frames(bts_data()->dl_tbf_idle_msec);
 	return frames_since_last_drain(fn) <= keep_time_frames;
 }
+
+/*
+ * This function returns the pointer to data which needs
+ * to be copied. Also updates the status of the block related to
+ * Split block handling in the RLC/MAC block.
+ */
+enum egprs_rlc_dl_reseg_bsn_state
+	gprs_rlcmac_dl_tbf::egprs_dl_get_data(int bsn, uint8_t **block_data)
+{
+	gprs_rlc_data *rlc_data = m_rlc.block(bsn);
+	egprs_rlc_dl_reseg_bsn_state *block_status_dl =
+				&rlc_data->spb_status.block_status_dl;
+
+	GprsCodingScheme &cs_current_trans = m_rlc.block(bsn)->cs_current_trans;
+	GprsCodingScheme &cs_init = m_rlc.block(bsn)->cs_init;
+	*block_data = &rlc_data->block[0];
+
+	/*
+	 * Table 10.3a.0.1 of 44.060
+	 * MCS6,9: second segment starts at 74/2 = 37
+	 * MCS5,7: second segment starts at 56/2 = 28
+	 * MCS8: second segment starts at 31
+	 * MCS4: second segment starts at 44/2 = 22
+	 */
+	if (cs_current_trans.headerTypeData() ==
+			GprsCodingScheme::HEADER_EGPRS_DATA_TYPE_3) {
+		if (*block_status_dl == EGPRS_RESEG_FIRST_SEG_SENT) {
+			switch (GprsCodingScheme::Scheme(cs_init)) {
+			case GprsCodingScheme::MCS6 :
+			case GprsCodingScheme::MCS9 :
+				*block_data = &rlc_data->block[37];
+				break;
+			case GprsCodingScheme::MCS7 :
+			case GprsCodingScheme::MCS5 :
+				*block_data = &rlc_data->block[28];
+				break;
+			case GprsCodingScheme::MCS8 :
+				*block_data = &rlc_data->block[31];
+				break;
+			case GprsCodingScheme::MCS4 :
+				*block_data = &rlc_data->block[22];
+				break;
+			default:
+				LOGP(DRLCMACDL, LOGL_ERROR, "Software error: "
+				"--%s hit invalid condition. headerType(%d) "
+				" blockstatus(%d) cs(%s) PLEASE FIX!\n", name(),
+				cs_current_trans.headerTypeData(),
+				*block_status_dl, cs_init.name());
+				break;
+
+			}
+			return EGPRS_RESEG_SECOND_SEG_SENT;
+		} else if ((cs_init.headerTypeData() ==
+				GprsCodingScheme::HEADER_EGPRS_DATA_TYPE_1) ||
+			(cs_init.headerTypeData() ==
+				GprsCodingScheme::HEADER_EGPRS_DATA_TYPE_2)) {
+			return EGPRS_RESEG_FIRST_SEG_SENT;
+		} else if ((GprsCodingScheme::Scheme(cs_init) ==
+					GprsCodingScheme::MCS4) &&
+				(GprsCodingScheme::Scheme(cs_current_trans) ==
+					GprsCodingScheme::MCS1)) {
+			return EGPRS_RESEG_FIRST_SEG_SENT;
+		}
+	}
+	return EGPRS_RESEG_DL_DEFAULT;
+}
+
+/*
+ * This function returns the status of split block
+ * for RLC/MAC block.
+ */
+unsigned int gprs_rlcmac_dl_tbf::get_egprs_dl_spb_status(const int bsn)
+{
+	const gprs_rlc_data *rlc_data = m_rlc.block(bsn);
+
+	return rlc_data->spb_status.block_status_dl;
+}
+
+/*
+ * This function returns the spb value to be sent OTA
+ * for RLC/MAC block.
+ */
+enum egprs_rlcmac_dl_spb gprs_rlcmac_dl_tbf::get_egprs_dl_spb(const int bsn)
+{
+	struct gprs_rlc_data *rlc_data = m_rlc.block(bsn);
+	egprs_rlc_dl_reseg_bsn_state block_status_dl =
+				rlc_data->spb_status.block_status_dl;
+
+	GprsCodingScheme &cs_current_trans = m_rlc.block(bsn)->cs_current_trans;
+	GprsCodingScheme &cs_init = m_rlc.block(bsn)->cs_init;
+
+	/* Table 10.4.8b.1 of 44.060 */
+	if (cs_current_trans.headerTypeData() ==
+			GprsCodingScheme::HEADER_EGPRS_DATA_TYPE_3) {
+	/*
+	 * if we are sending the second segment the spb should be 3
+	 * other wise it should be 2
+	 */
+		if (block_status_dl == EGPRS_RESEG_FIRST_SEG_SENT) {
+			return EGPRS_RLCMAC_DL_SEC_SEG;
+		} else if ((cs_init.headerTypeData() ==
+				GprsCodingScheme::HEADER_EGPRS_DATA_TYPE_1) ||
+			(cs_init.headerTypeData() ==
+				GprsCodingScheme::HEADER_EGPRS_DATA_TYPE_2)) {
+			return EGPRS_RLCMAC_DL_FIRST_SEG;
+		} else if ((GprsCodingScheme::Scheme(cs_init) ==
+					GprsCodingScheme::MCS4) &&
+				(GprsCodingScheme::Scheme(cs_current_trans) ==
+					GprsCodingScheme::MCS1)) {
+			return EGPRS_RLCMAC_DL_FIRST_SEG;
+		}
+	}
+	/* Non SPB cases 0 is reurned */
+	return EGPRS_RLCMAC_DL_NO_RETX;
+}