basic Sync checking. No protocol stuff yet; just checks that input events are well-behaved.

OpenRa.Game/Sync.cs

@@ -0,0 +1,57 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Reflection;
+
+namespace OpenRa.Game
+{
+	class SyncAttribute : Attribute { }
+
+	static class Sync
+	{
+		public static int CalculateSyncHash( object obj )
+		{
+			int hash = 0; // TODO: start with a more interesting initial value.
+
+			// TODO: cache the Syncable fields; maybe use DynamicMethod to make this fast?
+			// FIXME: does GetFields even give fields in a well-defined order?
+			const BindingFlags bf = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance;
+			foreach( var field in obj.GetType().GetFields( bf ).Where( x => x.GetCustomAttributes( typeof( SyncAttribute ), true ).Length != 0 ) )
+			{
+				if( field.FieldType == typeof( int ) )
+					hash ^= (int)field.GetValue( obj );
+
+				else if( field.FieldType == typeof( Actor ) )
+				{
+					var a = (Actor)field.GetValue( obj );
+					if( a != null )
+						hash ^= (int)( a.ActorID << 16 );
+				}
+				else if( field.FieldType == typeof( TypeDictionary ) )
+				{
+					foreach( var o in (TypeDictionary)field.GetValue( obj ) )
+						hash += CalculateSyncHash( o );
+				}
+				else if( field.FieldType == typeof( bool ) )
+					hash ^= (bool)field.GetValue( obj ) ? 0xaaa : 0x555;
+
+				else if( field.FieldType == typeof( int2 ) )
+				{
+					var i2 = (int2)field.GetValue( obj );
+					hash ^= ( ( i2.X * 5 ) ^ ( i2.Y * 3 ) ) / 4;
+				}
+				else if( field.FieldType == typeof( Player ) )
+				{
+					var p = (Player)field.GetValue( obj );
+					if( p != null )
+					hash ^= p.Index * 0x567;
+				}
+				else
+					throw new NotImplementedException( "SyncAttribute on unhashable field" );
+			}
+
+			return hash;
+		}
+	}
+}