Updated CPos struct to use a bit field for all properties.

OpenRA.Game/CPos.cs

@@ -18,11 +18,28 @@ namespace OpenRA
 {
 	public struct CPos : IScriptBindable, ILuaAdditionBinding, ILuaSubtractionBinding, ILuaEqualityBinding, ILuaTableBinding, IEquatable<CPos>
 	{
-		public readonly int X, Y;
+		// Coordinates are packed in a 32 bit signed int
-		public readonly byte Layer;
+		// X and Y are 12 bits (signed): -2048...2047
+		// Layer is an unsigned byte
+		// Packing is XXXX XXXX XXXX YYYY YYYY YYYY LLLL LLLL
+		public readonly int Bits;
+
+		// X is padded to MSB, so bit shift does the correct sign extension
+		public int X { get { return Bits >> 20; } }
+
+		// Align Y with a short, cast, then shift the rest of the way
+		// The signed short bit shift does the correct sign extension
+		public int Y { get { return ((short)(Bits >> 4)) >> 4; } }
+
+		public byte Layer { get { return (byte)Bits; } }
+
+		public CPos(int bits) { Bits = bits; }
+		public CPos(int x, int y) : this(x, y, 0) { }
+		public CPos(int x, int y, byte layer)
+		{
+			Bits = (x & 0xFFF) << 20 | (y & 0xFFF) << 8 | layer;
+		}
 
-		public CPos(int x, int y) { X = x; Y = y; Layer = 0; }
-		public CPos(int x, int y, byte layer) { X = x; Y = y; Layer = layer; }
 		public static readonly CPos Zero = new CPos(0, 0, 0);
 
 		public static explicit operator CPos(int2 a) { return new CPos(a.X, a.Y); }
@@ -32,12 +49,12 @@ namespace OpenRA
 		public static CPos operator -(CPos a, CVec b) { return new CPos(a.X - b.X, a.Y - b.Y, a.Layer); }
 		public static CVec operator -(CPos a, CPos b) { return new CVec(a.X - b.X, a.Y - b.Y); }
 
-		public static bool operator ==(CPos me, CPos other) { return me.X == other.X && me.Y == other.Y && me.Layer == other.Layer; }
+		public static bool operator ==(CPos me, CPos other) { return me.Bits == other.Bits; }
 		public static bool operator !=(CPos me, CPos other) { return !(me == other); }
 
-		public override int GetHashCode() { return X.GetHashCode() ^ Y.GetHashCode() ^ Layer.GetHashCode(); }
+		public override int GetHashCode() { return Bits.GetHashCode(); }
 
-		public bool Equals(CPos other) { return X == other.X && Y == other.Y && Layer == other.Layer; }
+		public bool Equals(CPos other) { return Bits == other.Bits; }
 		public override bool Equals(object obj) { return obj is CPos && Equals((CPos)obj); }
 
 		public override string ToString() { return X + "," + Y; }

OpenRA.Game/Map/MapPreview.cs

@@ -56,7 +56,7 @@ namespace OpenRA
 		public readonly string[] categories;
 		public readonly int players;
 		public readonly Rectangle bounds;
-		public readonly int[] spawnpoints = { };
+		public readonly short[] spawnpoints = { };
 		public readonly MapGridType map_grid_type;
 		public readonly string minimap;
 		public readonly bool downloading;

OpenRA.Game/Network/Order.cs

@@ -128,7 +128,7 @@ namespace OpenRA
 									{
 										if (flags.HasField(OrderFields.TargetIsCell))
 										{
-											var cell = new CPos(r.ReadInt32(), r.ReadInt32(), r.ReadByte());
+											var cell = new CPos(r.ReadInt32());
 											var subCell = (SubCell)r.ReadByte();
 											if (world != null)
 												target = Target.FromCell(world, cell, subCell);
@@ -146,7 +146,7 @@ namespace OpenRA
 
 						var targetString = flags.HasField(OrderFields.TargetString) ? r.ReadString() : null;
 						var queued = flags.HasField(OrderFields.Queued);
-						var extraLocation = flags.HasField(OrderFields.ExtraLocation) ? new CPos(r.ReadInt32(), r.ReadInt32(), r.ReadByte()) : CPos.Zero;
+						var extraLocation = flags.HasField(OrderFields.ExtraLocation) ? new CPos(r.ReadInt32()) : CPos.Zero;
 						var extraData = flags.HasField(OrderFields.ExtraData) ? r.ReadUInt32() : 0;
 
 						if (world == null)

OpenRA.Game/Network/OrderIO.cs

@@ -58,9 +58,7 @@ namespace OpenRA.Network
 
 		public static void Write(this BinaryWriter w, CPos cell)
 		{
-			w.Write(cell.X);
+			w.Write(cell.Bits);
-			w.Write(cell.Y);
-			w.Write(cell.Layer);
 		}
 
 		public static void Write(this BinaryWriter w, WPos pos)

OpenRA.Test/OpenRA.Game/CPosTest.cs

@@ -0,0 +1,31 @@
+using System.Runtime.Remoting.Metadata;
+using NUnit.Framework;
+
+namespace OpenRA.Test
+{
+	[TestFixture]
+	public class CPosTest
+	{
+		[TestCase(TestName = "Packing x,y and layer into int")]
+		public void PackUnpackBits()
+		{
+			var values = new int[] { -2048, -1024, 0, 1024, 2047 };
+			var layerValues = new byte[] { 0, 128, 255 };
+
+			foreach (var x in values)
+			{
+				foreach (var y in values)
+				{
+					foreach (var layer in layerValues)
+					{
+						var cell = new CPos(x, y, layer);
+
+						Assert.AreEqual(x, cell.X);
+						Assert.AreEqual(y, cell.Y);
+						Assert.AreEqual(layer, cell.Layer);
+					}
+				}
+			}
+		}
+	}
+}

OpenRA.Test/OpenRA.Game/OrderTest.cs

@@ -64,7 +64,7 @@ namespace OpenRA.Test
 			var o = new Order("Test", null, Target.Invalid, true)
 			{
 				TargetString = "TargetString",
-				ExtraLocation = new CPos(int.MinValue, int.MaxValue, 128),
+				ExtraLocation = new CPos(2047, 2047, 128),
 				ExtraData = uint.MaxValue,
 				IsImmediate = true,
 			}.Serialize();

OpenRA.Test/OpenRA.Test.csproj

@@ -46,6 +46,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="OpenRA.Game\ActionQueueTest.cs" />
+    <Compile Include="OpenRA.Game\CPosTest.cs" />
     <Compile Include="OpenRA.Game\MiniYamlTest.cs" />
     <Compile Include="OpenRA.Game\ActorInfoTest.cs" />
     <Compile Include="OpenRA.Game\CoordinateTest.cs" />