From d682b6c5123012c3a356e71ba802141c28e49cd9 Mon Sep 17 00:00:00 2001
From: Robert Schmidt <robert.schmidt@openairinterface.org>
Date: Fri, 19 Sep 2025 12:44:37 +0200
Subject: [PATCH] Add function to read max DL ToA

Protect with mutex to allow reading from another thread.
---
 openair1/PHY/INIT/nr_init_ue.c                 |  1 +
 .../nr_dl_channel_estimation.c                 | 18 ++++++++++++++++++
 openair1/PHY/defs_nr_common.h                  |  3 +++
 3 files changed, 22 insertions(+)

diff --git a/openair1/PHY/INIT/nr_init_ue.c b/openair1/PHY/INIT/nr_init_ue.c
index 2dce10d9dc..7ab8a8863d 100644
--- a/openair1/PHY/INIT/nr_init_ue.c
+++ b/openair1/PHY/INIT/nr_init_ue.c
@@ -159,6 +159,7 @@ void init_nr_prs_ue_vars(PHY_VARS_NR_UE *ue)
         AssertFatal((prs_vars[idx]->prs_resource[k].prs_meas[j]!=NULL), "%s: PRS measurements malloc failed for gNB_id %d, rx_ant %d\n", __FUNCTION__, idx, j);
         prs_meas_t *m = prs_vars[idx]->prs_resource[k].prs_meas[j];
         m->next_dl_toa = m->dl_toa;
+        pthread_mutex_init(&m->dl_toa_mtx, NULL);
       }
     }
   }
diff --git a/openair1/PHY/NR_UE_ESTIMATION/nr_dl_channel_estimation.c b/openair1/PHY/NR_UE_ESTIMATION/nr_dl_channel_estimation.c
index 3af0937c48..de0b6d2b29 100644
--- a/openair1/PHY/NR_UE_ESTIMATION/nr_dl_channel_estimation.c
+++ b/openair1/PHY/NR_UE_ESTIMATION/nr_dl_channel_estimation.c
@@ -73,10 +73,28 @@ void peak_estimator(c16_t *buffer, int32_t buf_len, int32_t *peak_idx, int32_t *
 
 void set_prs_dl_toa(prs_meas_t *prs_meas, float dl_toa)
 {
+  int rc = pthread_mutex_lock(&prs_meas->dl_toa_mtx);
+  AssertFatal(rc == 0, "pthread_mutex_lock() failed: errno %d, %s\n", errno, strerror(errno));
   *prs_meas->next_dl_toa++ = dl_toa;
   if (prs_meas->next_dl_toa >= prs_meas->dl_toa + sizeofArray(prs_meas->dl_toa))
     prs_meas->next_dl_toa = prs_meas->dl_toa;
   LOG_D(NR_PHY, "next_dl_toa %p\n", prs_meas->next_dl_toa);
+  rc = pthread_mutex_unlock(&prs_meas->dl_toa_mtx);
+  AssertFatal(rc == 0, "pthread_mutex_unlock() failed: errno %d, %s\n", errno, strerror(errno));
+}
+
+float get_prs_max_dl_toa(prs_meas_t *prs_meas)
+{
+  float max = 0.0f;
+  int rc = pthread_mutex_lock(&prs_meas->dl_toa_mtx);
+  AssertFatal(rc == 0, "pthread_mutex_lock() failed: errno %d, %s\n", errno, strerror(errno));
+  for (int i = 0; i < sizeofArray(prs_meas->dl_toa); ++i) {
+    max = cmax(max, prs_meas->dl_toa[i]);
+    LOG_I(NR_PHY, "i %d dl_toa %.3f max %.3f\n", i, prs_meas->dl_toa[i], max);
+  }
+  rc = pthread_mutex_unlock(&prs_meas->dl_toa_mtx);
+  AssertFatal(rc == 0, "pthread_mutex_unlock() failed: errno %d, %s\n", errno, strerror(errno));
+  return max;
 }
 
 int nr_prs_channel_estimation(uint8_t gNB_id,
diff --git a/openair1/PHY/defs_nr_common.h b/openair1/PHY/defs_nr_common.h
index b4d61d32f9..23972fc9f2 100644
--- a/openair1/PHY/defs_nr_common.h
+++ b/openair1/PHY/defs_nr_common.h
@@ -38,6 +38,8 @@
 #include "impl_defs_nr.h"
 #include "PHY/CODING/nrPolar_tools/nr_polar_defs.h"
 
+#include <pthread.h>
+
 #define MAX_NUM_SUBCARRIER_SPACING 5
 #define NR_MAX_OFDM_SYMBOL_SIZE 8192
 
@@ -312,6 +314,7 @@ typedef struct {
     int32_t sfn;
     int8_t  slot;
     int8_t  rxAnt_idx;
+    pthread_mutex_t dl_toa_mtx; // protect reading of max from write
     // circular buffer to be able to read maximum of last estimations
     float dl_toa[128]; // set through set_prs_dl_toa()
     float *next_dl_toa;