Write XCC compatible mix files.

OpenRA.FileFormats/FileFormats/XccLocalDatabase.cs

@@ -10,6 +10,8 @@
 
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
+using System.Text;
 
 namespace OpenRA.FileFormats
 {
@@ -33,5 +35,33 @@ namespace OpenRA.FileFormats
 				Entries[i] = new string(chars.ToArray());
 			}
 		}
+
+		public XccLocalDatabase(IEnumerable<string> filenames)
+		{
+			Entries = filenames.ToArray();
+		}
+
+		public byte[] Data()
+		{
+			var data = new MemoryStream();
+			using (var writer = new BinaryWriter(data))
+			{
+				writer.Write(Encoding.ASCII.GetBytes("XCC by Olaf van der Spek"));
+				writer.Write(new byte[] {0x1A,0x04,0x17,0x27,0x10,0x19,0x80,0x00});
+
+				writer.Write((int)(Entries.Aggregate(Entries.Length, (a,b) => a + b.Length) + 52)); // Size
+				writer.Write((int)0); // Type
+				writer.Write((int)0); // Version
+				writer.Write((int)0); // Game/Format (0 == TD)
+				writer.Write((int)Entries.Length); // Entries
+				foreach (var e in Entries)
+				{
+					writer.Write(Encoding.ASCII.GetBytes(e));
+					writer.Write((byte)0);
+				}
+			}
+
+			return data.ToArray();
+		}
 	}
 }

OpenRA.FileFormats/Filesystem/MixFile.cs

@@ -39,8 +39,8 @@ namespace OpenRA.FileFormats
 				File.Delete(filename);
 
 			s = File.Create(filename);
-
-			// TODO: Add a local mix database.dat for compatibility with XCC Mixer
+			index = new Dictionary<uint, PackageEntry>();
+			contents.Add("local mix database.dat", new XccLocalDatabase(contents.Keys.Append("local mix database.dat")).Data());
 			Write(contents);
 		}