From 6a60cebd519b9c66a0ee5cd9155cea9270f1b66e Mon Sep 17 00:00:00 2001
From: Joachim Spange <joachim.spange@kd.kongsberg.com>
Date: Tue, 28 Jan 2025 11:19:38 +0100
Subject: [PATCH] =?UTF-8?q?=E2=9C=A8=20HDT?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/NmeaParser/Nmea/Hdt.cs                    | 64 +++++++++++++++++++
 .../NmeaParser.Tests/NmeaMessages.cs          | 11 ++++
 2 files changed, 75 insertions(+)
 create mode 100644 src/NmeaParser/Nmea/Hdt.cs

diff --git a/src/NmeaParser/Nmea/Hdt.cs b/src/NmeaParser/Nmea/Hdt.cs
new file mode 100644
index 0000000..8aebaf2
--- /dev/null
+++ b/src/NmeaParser/Nmea/Hdt.cs
@@ -0,0 +1,64 @@
+//  *******************************************************************************
+//  *  Licensed under the Apache License, Version 2.0 (the "License");
+//  *  you may not use this file except in compliance with the License.
+//  *  You may obtain a copy of the License at
+//  *
+//  *  http://www.apache.org/licenses/LICENSE-2.0
+//  *
+//  *   Unless required by applicable law or agreed to in writing, software
+//  *   distributed under the License is distributed on an "AS IS" BASIS,
+//  *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  *   See the License for the specific language governing permissions and
+//  *   limitations under the License.
+//  ******************************************************************************
+
+using System;
+using System.Globalization;
+
+namespace NmeaParser.Messages
+{
+    /// <summary>
+    ///     Heading from True North
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         1.: Heading in degrees
+    ///         2.: Indicates heading relative to True North
+    ///     </para>
+    ///     <para>
+    ///         Actual vessel heading in degrees True produced by any device or system producing true heading
+    ///     </para>
+    /// </remarks>
+    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "HeHdt")]
+    [NmeaMessageType("--HDT")]
+    public class Hdt : NmeaMessage
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Hdt"/> class.
+        /// </summary>
+        /// <param name="type">The message type</param>
+        /// <param name="message">The NMEA message values.</param>
+        public Hdt(string type, string[] message) : base(type, message)
+        {
+            if (message == null || message.Length < 2)
+                throw new ArgumentException("Invalid Hdt", "message");
+
+            // Extract the heading in degrees
+            HeadingInDeg = double.TryParse(message[0], NumberStyles.Float, CultureInfo.InvariantCulture, out var heading)
+                ? heading 
+                : double.NaN;
+
+            HeadingRelToTrueNorth = message[1] == "T";
+        }
+
+        /// <summary>
+        ///     Heading in degrees
+        /// </summary>
+        public double HeadingInDeg { get; }
+
+        /// <summary>
+        ///     T: Indicates heading relative to True North
+        /// </summary>
+        public bool HeadingRelToTrueNorth { get; }
+    }
+}
\ No newline at end of file
diff --git a/src/UnitTests/NmeaParser.Tests/NmeaMessages.cs b/src/UnitTests/NmeaParser.Tests/NmeaMessages.cs
index b6cbc1c..1467fa6 100644
--- a/src/UnitTests/NmeaParser.Tests/NmeaMessages.cs
+++ b/src/UnitTests/NmeaParser.Tests/NmeaMessages.cs
@@ -296,6 +296,17 @@ namespace NmeaParser.Tests
             Assert.AreEqual(-1, gga.DgpsStationId);
         }
 
+        [TestMethod]
+        public void TestHEHDT()
+        {
+            const string input = "$HEHDT,13.37,T*29";
+            var msg = NmeaMessage.Parse(input);
+            Assert.IsInstanceOfType(msg, typeof(Hdt));
+            Hdt hdt = (Hdt)msg;
+            Assert.AreEqual(13.37, hdt.HeadingInDeg);
+            Assert.IsTrue(hdt.HeadingRelToTrueNorth);
+        }
+
         [TestMethod]
         public void TestPtlna()
         {