--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/druntime/src/compiler/dmd/arraycat.d	Tue Jun 02 17:43:06 2009 +0100
@@ -0,0 +1,42 @@
+/**
+ * Implementation of array copy support routines.
+ *
+ * Copyright: Copyright Digital Mars 2004 - 2009.
+ * License:   <a href="http://www.boost.org/LICENSE_1_0.txt>Boost License 1.0</a>.
+ * Authors:   Walter Bright, Sean Kelly
+ *
+ *          Copyright Digital Mars 2004 - 2009.
+ * Distributed under the Boost Software License, Version 1.0.
+ *    (See accompanying file LICENSE_1_0.txt or copy at
+ *          http://www.boost.org/LICENSE_1_0.txt)
+ */
+module rt.arraycat;
+
+private
+{
+    import core.stdc.string;
+    debug import core.stdc.stdio;
+}
+
+extern (C):
+
+byte[] _d_arraycopy(size_t size, byte[] from, byte[] to)
+{
+    debug printf("f = %p,%d, t = %p,%d, size = %d\n",
+                 from.ptr, from.length, to.ptr, to.length, size);
+
+    if (to.length != from.length)
+    {
+        throw new Exception("lengths don't match for array copy");
+    }
+    else if (to.ptr + to.length * size <= from.ptr ||
+             from.ptr + from.length * size <= to.ptr)
+    {
+        memcpy(to.ptr, from.ptr, to.length * size);
+    }
+    else
+    {
+        throw new Exception("overlapping array copy");
+    }
+    return to;
+}