Imported Upstream version 5.0.0.42

Former-commit-id: fd56571888259555122d8a0f58c68838229cea2b

external/linker/cecil/Mono.Cecil.PE/ByteBufferEqualityComparer.cs

@@ -0,0 +1,60 @@
+//
+// Author:
+//   Jb Evain (jbevain@gmail.com)
+//
+// Copyright (c) 2008 - 2015 Jb Evain
+// Copyright (c) 2008 - 2011 Novell, Inc.
+//
+// Licensed under the MIT/X11 license.
+//
+
+using System;
+using System.Collections.Generic;
+
+namespace Mono.Cecil.PE {
+
+	sealed class ByteBufferEqualityComparer : IEqualityComparer<ByteBuffer> {
+
+		public bool Equals (ByteBuffer x, ByteBuffer y)
+		{
+			if (x.length != y.length)
+				return false;
+
+			var x_buffer = x.buffer;
+			var y_buffer = y.buffer;
+
+			for (int i = 0; i < x.length; i++)
+				if (x_buffer [i] != y_buffer [i])
+					return false;
+
+			return true;
+		}
+
+		public int GetHashCode (ByteBuffer buffer)
+		{
+#if !BYTE_BUFFER_WELL_DISTRIBUTED_HASH
+			var hash = 0;
+			var bytes = buffer.buffer;
+			for (int i = 0; i < buffer.length; i++)
+				hash = (hash * 37) ^ bytes [i];
+
+			return hash;
+#else
+			const uint p = 16777619;
+			uint hash = 2166136261;
+
+			var bytes = buffer.buffer;
+			for (int i = 0; i < buffer.length; i++)
+			    hash = (hash ^ bytes [i]) * p;
+
+			hash += hash << 13;
+			hash ^= hash >> 7;
+			hash += hash << 3;
+			hash ^= hash >> 17;
+			hash += hash << 5;
+
+			return (int) hash;
+#endif
+		}
+	}
+}