c#: Add channel method to get label

Signed-off-by: Dan Nechita <[email protected]>

bindings/csharp/Channel.cs

@@ -167,6 +167,9 @@ public struct DataFormat
         [DllImport(IioLib.dllname, CallingConvention = CallingConvention.Cdecl)]
         private static extern IntPtr iio_channel_get_name(IntPtr chn);
 
+        [DllImport(IioLib.dllname, CallingConvention = CallingConvention.Cdecl)]
+        private static extern IntPtr iio_channel_get_label(IntPtr chn);
+
         [DllImport(IioLib.dllname, CallingConvention = CallingConvention.Cdecl)]
         private static extern uint iio_channel_get_attrs_count(IntPtr chn);
 
@@ -216,6 +219,9 @@ private static extern uint iio_channel_write(IntPtr chn,
         /// <summary>The name of this channel.</summary>
         public readonly string name;
 
+        /// <summary>The label of this channel.</summary>
+        public string label { get; private set; }
+
         /// <summary>An identifier of this channel.</summary>
         /// <remarks>It is possible that two channels have the same ID,
         /// if one is an input channel and the other is an output channel.</remarks>
@@ -273,6 +279,9 @@ internal Channel(Device dev, IntPtr chn)
                 name = Marshal.PtrToStringAnsi(name_ptr);
             }
 
+            IntPtr label_ptr = iio_channel_get_label(this.chn);
+            label = label_ptr == IntPtr.Zero ? "" : Marshal.PtrToStringAnsi(label_ptr);
+
             id = Marshal.PtrToStringAnsi(iio_channel_get_id(this.chn));
             output = iio_channel_is_output(this.chn);
             scan_element = iio_channel_is_scan_element(this.chn);