From 76d767cbe84fbfecfd3003af622f949f04aadbe4 Mon Sep 17 00:00:00 2001
From: Jacob Erlbeck <jerlbeck@sysmocom.de>
Date: Mon, 28 Sep 2015 18:54:32 +0200
Subject: [PATCH] edge: Support EGPRS in packet uplink assignment message

Currently the Encoding::write_packet_uplink_assignment method only
supports the GPRS variant of the message.

This commit adds the missing EGPRS variant to the encoder.

Sponsored-by: On-Waves ehf
---
 src/encoding.cpp | 48 +++++++++++++++++++++++++++++++++++++-----------
 src/encoding.h   |  2 +-
 src/tbf.cpp      |  2 +-
 3 files changed, 39 insertions(+), 13 deletions(-)

diff --git a/src/encoding.cpp b/src/encoding.cpp
index e0b545c0..7f4bf797 100644
--- a/src/encoding.cpp
+++ b/src/encoding.cpp
@@ -167,7 +167,7 @@ void Encoding::write_packet_uplink_assignment(
 	bitvec * dest, uint8_t old_tfi,
 	uint8_t old_downlink, uint32_t tlli, uint8_t use_tlli,
 	struct gprs_rlcmac_ul_tbf *tbf, uint8_t poll, uint8_t alpha,
-	uint8_t gamma, int8_t ta_idx)
+	uint8_t gamma, int8_t ta_idx, int8_t use_egprs)
 {
 	// TODO We should use our implementation of encode RLC/MAC Control messages.
 	unsigned wp = 0;
@@ -191,16 +191,42 @@ void Encoding::write_packet_uplink_assignment(
 		bitvec_write_field(dest, wp,old_tfi,5); // TFI
 	}
 
-	bitvec_write_field(dest, wp,0x0,1); // Message escape
-	bitvec_write_field(dest, wp,tbf->current_cs()-1, 2); // CHANNEL_CODING_COMMAND 
-	bitvec_write_field(dest, wp,0x1,1); // TLLI_BLOCK_CHANNEL_CODING 
-	bitvec_write_field(dest, wp,0x1,1); // switch TIMING_ADVANCE_VALUE = on
-	bitvec_write_field(dest, wp,tbf->ta(),6); // TIMING_ADVANCE_VALUE
-	if (ta_idx < 0) {
-		bitvec_write_field(dest, wp,0x0,1);   // switch TIMING_ADVANCE_INDEX = off
-	} else {
-		bitvec_write_field(dest, wp,0x1,1);   // switch TIMING_ADVANCE_INDEX = on
-		bitvec_write_field(dest, wp,ta_idx,4);   // TIMING_ADVANCE_INDEX
+	if (!use_egprs) {
+		bitvec_write_field(dest, wp,0x0,1); // Message escape
+		bitvec_write_field(dest, wp,tbf->current_cs()-1, 2); // CHANNEL_CODING_COMMAND 
+		bitvec_write_field(dest, wp,0x1,1); // TLLI_BLOCK_CHANNEL_CODING 
+		bitvec_write_field(dest, wp,0x1,1); // switch TIMING_ADVANCE_VALUE = on
+		bitvec_write_field(dest, wp,tbf->ta(),6); // TIMING_ADVANCE_VALUE
+		if (ta_idx < 0) {
+			bitvec_write_field(dest, wp,0x0,1);   // switch TIMING_ADVANCE_INDEX = off
+		} else {
+			bitvec_write_field(dest, wp,0x1,1);   // switch TIMING_ADVANCE_INDEX = on
+			bitvec_write_field(dest, wp,ta_idx,4);   // TIMING_ADVANCE_INDEX
+		}
+
+	} else { /* EPGRS */
+		bitvec_write_field(dest, wp,0x1,1); // Message escape
+		bitvec_write_field(dest, wp,0x0,2); // EGPRS message contents
+		bitvec_write_field(dest, wp,0x0,1); // No CONTENTION_RESOLUTION_TLLI
+		bitvec_write_field(dest, wp,0x0,1); // No COMPACT reduced MA
+		bitvec_write_field(dest, wp,tbf->current_cs()-1, 4); // EGPRS Modulation and Coding IE
+		bitvec_write_field(dest, wp,0x0,1); // No RESEGMENT
+		bitvec_write_field(dest, wp,0x0,5); // EGPRS Window Size = 64
+		bitvec_write_field(dest, wp,0x0,1); // No Access Technologies Request
+		bitvec_write_field(dest, wp,0x0,1); // No ARAC RETRANSMISSION REQUEST
+		bitvec_write_field(dest, wp,0x1,1); // TLLI_BLOCK_CHANNEL_CODING 
+		bitvec_write_field(dest, wp,0x0,1); // No BEP_PERIOD2
+
+		bitvec_write_field(dest, wp,0x1,1); // switch TIMING_ADVANCE_VALUE = on
+		bitvec_write_field(dest, wp,tbf->ta(),6); // TIMING_ADVANCE_VALUE
+		if (ta_idx < 0) {
+			bitvec_write_field(dest, wp,0x0,1);   // switch TIMING_ADVANCE_INDEX = off
+		} else {
+			bitvec_write_field(dest, wp,0x1,1);   // switch TIMING_ADVANCE_INDEX = on
+			bitvec_write_field(dest, wp,ta_idx,4);   // TIMING_ADVANCE_INDEX
+		}
+
+		bitvec_write_field(dest, wp,0x0,1); // No Packet Extended Timing Advance
 	}
 
 #if 1
diff --git a/src/encoding.h b/src/encoding.h
index 0004c42b..ac66838d 100644
--- a/src/encoding.h
+++ b/src/encoding.h
@@ -48,7 +48,7 @@ public:
 			bitvec * dest, uint8_t old_tfi,
 			uint8_t old_downlink, uint32_t tlli, uint8_t use_tlli, 
 			struct gprs_rlcmac_ul_tbf *tbf, uint8_t poll, uint8_t alpha,
-			uint8_t gamma, int8_t ta_idx);
+			uint8_t gamma, int8_t ta_idx, int8_t use_egprs);
 
 	static void write_packet_downlink_assignment(RlcMacDownlink_t * block, uint8_t old_tfi,
 			uint8_t old_downlink, struct gprs_rlcmac_tbf *tbf, uint8_t poll,
diff --git a/src/tbf.cpp b/src/tbf.cpp
index 6c1320fc..0eb99830 100644
--- a/src/tbf.cpp
+++ b/src/tbf.cpp
@@ -923,7 +923,7 @@ struct msgb *gprs_rlcmac_tbf::create_ul_ass(uint32_t fn)
 	Encoding::write_packet_uplink_assignment(bts_data(), ass_vec, m_tfi,
 		(direction == GPRS_RLCMAC_DL_TBF), tlli(),
 		is_tlli_valid(), new_tbf, 1, bts_data()->alpha,
-		bts_data()->gamma, -1);
+		bts_data()->gamma, -1, 0);
 	bitvec_pack(ass_vec, msgb_put(msg, 23));
 	RlcMacDownlink_t * mac_control_block = (RlcMacDownlink_t *)talloc_zero(tall_pcu_ctx, RlcMacDownlink_t);
 	LOGP(DRLCMAC, LOGL_DEBUG, "+++++++++++++++++++++++++ TX : Packet Uplink Assignment +++++++++++++++++++++++++\n");