Add ThunderboltSerialPort class to interface with the Thunderbolt's serial port

ThunderboltTimeSync.sln

@@ -1,7 +1,7 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio 14
-VisualStudioVersion = 14.0.25123.0
+VisualStudioVersion = 14.0.25420.1
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ThunderboltTimeSync", "ThunderboltTimeSync\ThunderboltTimeSync.csproj", "{7D970120-F57C-4541-BD54-2602C59EB8BA}"
 EndProject

ThunderboltTimeSync/FormMain.cs

@@ -1,5 +1,7 @@
-using System;
+using System.Collections.Generic;
 using System.Diagnostics;
+using System.IO.Ports;
+using System.Linq;
 using System.Windows.Forms;
 
 namespace ThunderboltTimeSync {
@@ -18,16 +20,19 @@ namespace ThunderboltTimeSync {
 
 			InitializeComponent();
 
-			Debug.WriteLine(SystemTimeUtils.GetSystemTime().ToString("yyyy-MM-ddTHH:mm:ssK.ffff"));
-			try {
-				SystemTimeUtils.SetSystemTime(new DateTime(
-					2000, 1, 1,
-					10, 0, 0, 0
-				));
-			} catch (SystemTimeUtils.SystemTimeException stEx) {
-				Debug.WriteLine(string.Format("Setting system time failed: \"{0}\"", stEx.Message));
-			}
-			Debug.WriteLine(SystemTimeUtils.GetSystemTime().ToString("yyyy-MM-ddTHH:mm:ssK.ffff"));
+			ThunderboltSerialPort tbsp = new ThunderboltSerialPort(new SerialPort("COM3"));
+
+			tbsp.PacketReceived += (List<byte> packetBuffer) => {
+				List<string> byteStrings = packetBuffer.Select(x => string.Format("{0:X2}", x)).ToList();
+				Debug.WriteLine(
+					string.Format(
+						"Packet received: {0}",
+						string.Join(" ", byteStrings)
+					)
+				);
+			};
+
+			tbsp.Open();
 		}
 	}
 }

ThunderboltTimeSync/ThunderboltSerialPort.cs

@@ -0,0 +1,88 @@
+using System.Collections.Generic;
+using System.IO.Ports;
+
+namespace ThunderboltTimeSync {
+	public class ThunderboltSerialPort {
+		private static readonly byte CHAR_DLE = 0x10;
+		private static readonly byte CHAR_ETX = 0x03;
+
+		private List<byte> packetBuffer;
+		private bool inPacket;
+
+		private SerialPort serialPort;
+
+		/// <summary>
+		/// A delegate which is called when a full packet is received over the serial port.
+		/// The byte buffer passed in contains the initial [DLE], and final [DLE][ETX]. The buffer is completely unparsed and remains stuffed.
+		/// </summary>
+		/// <param name="packetBuffer">A byte buffer which contains the packet.</param>
+		public delegate void PacketReceivedEventHandler(List<byte> packetBuffer);
+
+		/// <summary>
+		/// An event which is called when a full packet is received over the serial port.
+		/// Refer to <see cref="PacketReceivedEventHandler"/> for more information.
+		/// </summary>
+		public event PacketReceivedEventHandler PacketReceived;
+
+		/// <summary>
+		/// Creates an instance of the ThunderboltSerialPort class, which processes serial data from a Thunderbolt and 
+		/// The serial port passed into the function must not be opened, or have a delegate already attached to the DataReceived event.
+		/// </summary>
+		/// <param name="serialPort">The serial port on which to communicate with the Thunderbolt.</param>
+		public ThunderboltSerialPort(SerialPort serialPort) {
+			packetBuffer = new List<byte>();
+			inPacket = false;
+
+			this.serialPort = serialPort;
+			serialPort.DataReceived += DataReceived;
+		}
+
+		/// <summary>
+		/// Begins processing serial data.
+		/// </summary>
+		public void Open() {
+			serialPort.Open();
+		}
+
+		private void DataReceived(object sender, SerialDataReceivedEventArgs e) {
+			int possibleCurrentByte;
+
+			while ((possibleCurrentByte = serialPort.ReadByte()) != -1) {
+				// Once we're sure the byte that was read wasn't -1 (which signifies the end of the read), we're safe to cast to a byte
+				byte currentByte = (byte) possibleCurrentByte;
+
+				if (inPacket) {
+					packetBuffer.Add(currentByte);
+
+					// Check buffer length to ensure we've reached a plausible end of packet.
+					// 5 bytes is [DLE]<id><1 byte of data>[DLE][ETX]
+					if (currentByte == CHAR_ETX && packetBuffer.Count >= 5) {
+						int numberOfPrecedingDLEs = 0;
+
+						// Count number of DLEs, excluding the first two bytes (initial DLE and id)
+						for (int i = 2; i < packetBuffer.Count; ++i) {
+							if (packetBuffer[i] == CHAR_DLE) {
+								++numberOfPrecedingDLEs;
+							}
+						}
+
+						// Odd number of DLEs means the ETX does in fact signify the end of the packet
+						if (numberOfPrecedingDLEs % 2 == 1) {
+							PacketReceived?.Invoke(packetBuffer);
+
+							packetBuffer.Clear();
+							inPacket = false;
+						}
+					}
+				} else {
+					// A DLE received when not currently in a packet signifies the beginning of a packet
+					if (currentByte == CHAR_DLE) {
+						packetBuffer.Add(currentByte);
+
+						inPacket = true;
+					}
+				}
+			}
+		}
+	}
+}

ThunderboltTimeSync/ThunderboltTimeSync.csproj

@@ -55,6 +55,7 @@
     <Compile Include="Program.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="SystemTimeUtils.cs" />
+    <Compile Include="ThunderboltSerialPort.cs" />
     <EmbeddedResource Include="FormMain.resx">
       <DependentUpon>FormMain.cs</DependentUpon>
     </EmbeddedResource>