From b17a5189b7a40faf033df690e6b5ad057bdf7201 Mon Sep 17 00:00:00 2001
From: Melissa Elkadi <melissa@episci.com>
Date: Tue, 12 Oct 2021 10:27:15 -0700
Subject: [PATCH] Adding timing informtion to rx'd slot indictions

Ensuring in the NRUE that the slot indications we
process are 500us apart.
---
 executables/nr-ue.c                         | 20 ++++++++++++----
 openair2/LAYER2/NR_MAC_UE/mac_defs.h        |  5 ++++
 openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c | 26 +++++++++++++++------
 3 files changed, 40 insertions(+), 11 deletions(-)

diff --git a/executables/nr-ue.c b/executables/nr-ue.c
index 2ac77f66b2..493fdf5deb 100644
--- a/executables/nr-ue.c
+++ b/executables/nr-ue.c
@@ -391,8 +391,9 @@ static void *NRUE_phy_stub_standalone_pnf_task(void *arg)
   NR_UL_TIME_ALIGNMENT_t ul_time_alignment;
   memset(&ul_time_alignment, 0, sizeof(ul_time_alignment));
   int last_sfn_slot = -1;
-  uint16_t *sfn_slot_p;
   int sfn_slot;
+  uint64_t last_time_stamp = 0;
+  sfn_slot_info_t *sfn_slot_info;
 
   while (!oai_exit)
   {
@@ -401,14 +402,14 @@ static void *NRUE_phy_stub_standalone_pnf_task(void *arg)
       LOG_E(NR_MAC, "sem_wait() error\n");
       abort();
     }
-    sfn_slot_p = get_queue(&nr_sfn_slot_queue);
-    if (sfn_slot_p == NULL)
+    sfn_slot_info = get_queue(&nr_sfn_slot_queue);
+    if (sfn_slot_info == NULL)
     {
       LOG_D(MAC, "get_queue(&nr_sfn_slot_queue) == NULL!\n");
       continue;
     }
 
-    sfn_slot = *sfn_slot_p;
+    sfn_slot = sfn_slot_info->sfn_slot;
     if (sfn_slot == last_sfn_slot)
     {
       LOG_D(NR_MAC, "repeated sfn_sf = %d.%d\n",
@@ -416,6 +417,17 @@ static void *NRUE_phy_stub_standalone_pnf_task(void *arg)
       continue;
     }
     last_sfn_slot = sfn_slot;
+     LOG_D(NR_MAC, "The received sfn/slot [%d %d], last time stamp %ld, current time stamp %ld\n",
+            NFAPI_SFNSLOT2SFN(sfn_slot), NFAPI_SFNSLOT2SLOT(sfn_slot), last_time_stamp, sfn_slot_info->time_stamp);
+
+    uint64_t delta = sfn_slot_info->time_stamp - last_time_stamp;
+    if (delta < 500)
+    {
+      LOG_D(NR_MAC, "sfn/slot [%d %d] has been received too quickly! Delta = %ld. Will sleep for %ld us\n",
+            NFAPI_SFNSLOT2SFN(sfn_slot), NFAPI_SFNSLOT2SLOT(sfn_slot), delta, 500 - delta);
+      usleep(500 - delta);
+    }
+    last_time_stamp = sfn_slot_info->time_stamp;
 
     module_id_t mod_id = 0;
     NR_UE_MAC_INST_t *mac = get_mac_inst(mod_id);
diff --git a/openair2/LAYER2/NR_MAC_UE/mac_defs.h b/openair2/LAYER2/NR_MAC_UE/mac_defs.h
index 8aa1be3e59..4873b0027c 100755
--- a/openair2/LAYER2/NR_MAC_UE/mac_defs.h
+++ b/openair2/LAYER2/NR_MAC_UE/mac_defs.h
@@ -443,6 +443,11 @@ typedef struct {
 
 } NR_UE_MAC_INST_t;
 
+typedef struct sfn_slot_info {
+    uint16_t sfn_slot;
+    uint64_t time_stamp;
+} sfn_slot_info_t;
+
 typedef enum seach_space_mask_e {
     type0_pdcch  = 0x1, 
     type0a_pdcch = 0x2,
diff --git a/openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c b/openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c
index c1d5a04a2d..64182330ff 100644
--- a/openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c
+++ b/openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c
@@ -748,7 +748,17 @@ static void enqueue_nr_nfapi_msg(void *buffer, ssize_t len, nfapi_p7_message_hea
     return;
 }
 
-uint16_t sfn_slot_pool[512];
+static uint64_t clock_usec()
+{
+    struct timespec t;
+    if (clock_gettime(CLOCK_MONOTONIC, &t) == -1)
+    {
+        abort();
+    }
+    return (uint64_t)t.tv_sec * 1000000 + (t.tv_nsec / 1000);
+}
+
+sfn_slot_info_t sfn_slot_pool[512];
 uint16_t sfn_slot_id;
 void *nrue_standalone_pnf_task(void *context)
 {
@@ -783,7 +793,12 @@ void *nrue_standalone_pnf_task(void *context)
       memcpy((void *)&sfn_slot, buffer, sizeof(sfn_slot));
       current_sfn_slot = sfn_slot;
 
-      sfn_slot_pool[sfn_slot_id] = sfn_slot;
+      sfn_slot_pool[sfn_slot_id].sfn_slot = sfn_slot;
+      sfn_slot_pool[sfn_slot_id].time_stamp = clock_usec();
+      sfn = NFAPI_SFNSLOT2SFN(sfn_slot);
+      slot = NFAPI_SFNSLOT2SLOT(sfn_slot);
+      LOG_I(NR_PHY, "Received from proxy sfn %d slot %d and time_stamp = %ld\n",
+            sfn, slot, sfn_slot_pool[sfn_slot_id].time_stamp);
 
       if (!put_queue(&nr_sfn_slot_queue, &sfn_slot_pool[sfn_slot_id]))
       {
@@ -797,10 +812,6 @@ void *nrue_standalone_pnf_task(void *context)
         LOG_E(NR_PHY, "sem_post() error\n");
         abort();
       }
-
-      sfn = NFAPI_SFNSLOT2SFN(sfn_slot);
-      slot = NFAPI_SFNSLOT2SLOT(sfn_slot);
-      LOG_I(NR_PHY, "Received from proxy sfn %d slot %d\n", sfn, slot);
     }
     else if (len == sizeof(nr_phy_channel_params_t))
     {
@@ -808,7 +819,8 @@ void *nrue_standalone_pnf_task(void *context)
       memcpy(&ch_info, buffer, sizeof(nr_phy_channel_params_t));
       current_sfn_slot = ch_info.sfn_slot;
 
-      sfn_slot_pool[sfn_slot_id] = ch_info.sfn_slot;
+      sfn_slot_pool[sfn_slot_id].sfn_slot = ch_info.sfn_slot;
+      sfn_slot_pool[sfn_slot_id].time_stamp = clock_usec();
 
       if (!put_queue(&nr_sfn_slot_queue, &sfn_slot_pool[sfn_slot_id]))
       {