From dc08c1e4cb0bb26e02219f49bb3f6eb9801fe764 Mon Sep 17 00:00:00 2001
From: Magnus Lundborg <lundborg.magnus@gmail.com>
Date: Wed, 30 Oct 2013 11:05:22 +0100
Subject: Added utility function to get time of frame.


diff --git a/include/tng_io.h b/include/tng_io.h
index c31d8a2..e26089d 100644
--- a/include/tng_io.h
+++ b/include/tng_io.h
@@ -2142,6 +2142,19 @@ tng_function_status DECLSPECDLLEXPORT tng_util_trajectory_open
  */
 tng_function_status DECLSPECDLLEXPORT tng_util_trajectory_close
                 (tng_trajectory_t *tng_data_p);
+
+/**
+ * @brief High-level function for getting the time (in seconds) of a frame.
+ * @param tng_data is the trajectory containing the frame.
+ * @param frame_nr is the frame number of which to get the time.
+ * @param time is set to the time (in seconds) of the specified frame.
+ * @return TNG_SUCCESS (0) if successful or TNG_FAILURE (1) if a
+ * minor error has occured.
+ */
+tng_function_status DECLSPECDLLEXPORT tng_util_time_of_frame_get
+                (tng_trajectory_t tng_data,
+                 const int64_t frame_nr,
+                 double *time);
 /*
 // tng_function_status DECLSPECDLLEXPORT tng_util_trajectory_molecules_get
 //                 (tng_trajectory_t tng_data,
diff --git a/src/lib/tng_io.c b/src/lib/tng_io.c
index 69dbadd..dccbf03 100644
--- a/src/lib/tng_io.c
+++ b/src/lib/tng_io.c
@@ -14652,6 +14652,32 @@ tng_function_status DECLSPECDLLEXPORT tng_util_trajectory_close
     return(tng_trajectory_destroy(tng_data_p));
 }
 
+tng_function_status DECLSPECDLLEXPORT tng_util_time_of_frame_get
+                (tng_trajectory_t tng_data,
+                 const int64_t frame_nr,
+                 double *time)
+{
+    int64_t first_frame;
+
+    tng_trajectory_frame_set_t frame_set;
+    tng_function_status stat;
+    
+    stat = tng_frame_set_of_frame_find(tng_data, frame_nr);
+    if(stat != TNG_SUCCESS)
+    {
+        printf("Cannot find frame nr %"PRId64". %s: %d\n",
+               frame_nr, __FILE__, __LINE__);
+        return(stat);
+    }
+    
+    frame_set = &tng_data->current_trajectory_frame_set;
+    first_frame = frame_set->first_frame;
+    
+    *time = frame_set->first_frame_time + (tng_data->time_per_frame * frame_nr - first_frame);
+    
+    return(TNG_SUCCESS);
+}
+                
 tng_function_status DECLSPECDLLEXPORT tng_util_trajectory_molecules_get
                 (tng_trajectory_t tng_data,
                  int64_t *n_mols,
-- 
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