From 8e1b9b9f5bf81de71d2c061be0af5a660665967c Mon Sep 17 00:00:00 2001
From: Pedro Alvarez <pedro.alvarez@softwareradiosystems.com>
Date: Wed, 3 Jul 2019 18:51:44 +0100
Subject: [PATCH] Starting to implement the receive function of PDCP NR.

---
 lib/include/srslte/upper/pdcp_entity_nr.h | 15 +++++----------
 lib/src/upper/pdcp_entity_nr.cc           | 21 ++++++++++++++++++---
 2 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/lib/include/srslte/upper/pdcp_entity_nr.h b/lib/include/srslte/upper/pdcp_entity_nr.h
index 655edc963..f0986b915 100644
--- a/lib/include/srslte/upper/pdcp_entity_nr.h
+++ b/lib/include/srslte/upper/pdcp_entity_nr.h
@@ -77,19 +77,14 @@ private:
   uint16_t sn_len_bytes = 0;
 
   // State variables: 3GPP TS 38.323 v15.2.0, section 7.1
-  uint32_t tx_next = 0;
-  uint32_t rx_next = 0;
-  uint32_t rx_deliv = 0; 
-  uint32_t rx_reord = 0; 
- 
+  uint32_t tx_next  = 0; // COUNT value of next SDU to be transmitted.
+  uint32_t rx_next  = 0; // COUNT value of next SDU expected to be received.
+  uint32_t rx_deliv = 0; // COUNT value of first SDU not delivered to upper layers, but still waited for.
+  uint32_t rx_reord = 0; // COUNT value following the COUNT value of PDCP Data PDU which triggered t-Reordering.
+
   // Constants: 3GPP TS 38.323 v15.2.0, section 7.2
   uint32_t window_size = 0;
 };
 
-/****************************************************************************
- * Pack/Unpack helper functions
- * Ref: 3GPP TS 38.323 v15.2.0
- ***************************************************************************/
-
 } // namespace srslte
 #endif // SRSLTE_PDCP_ENTITY_NR_H
diff --git a/lib/src/upper/pdcp_entity_nr.cc b/lib/src/upper/pdcp_entity_nr.cc
index d0e9aa982..739779e08 100644
--- a/lib/src/upper/pdcp_entity_nr.cc
+++ b/lib/src/upper/pdcp_entity_nr.cc
@@ -115,11 +115,26 @@ void pdcp_entity_nr::write_pdu(unique_byte_buffer_t pdu)
   cipher_decript(pdu);
 
   // Check valid rcvd_count
-  if (rcvd_count < rx_deliv /*|| received_before (TODO)*/) {
+  if (rcvd_count < rx_deliv /*|| check_received_before() TODO*/) {
     return; // Invalid count, drop.
   }
 
-  //
-  if(rcvd_count >= rx_next)
+  // Store PDU in reception buffer
+  // TODO
+
+  // Update RX_NEXT
+  if(rcvd_count >= rx_next){
+    rx_next = rcvd_count + 1;
+  }
   
+  // Deliver to upper layers (TODO support in order delivery)
+  if (is_control()) {
+    rrc->write_pdu(pdu);
+  } else {
+    gw->write_pdu(pdu);
+  }
+  
+  // Not clear how to update RX_DELIV without reception buffer (TODO) 
+
+  // TODO handle reordering timers
 }