add XCore architecture
diff --git a/HACK.TXT b/HACK.TXT
index 8516cb3..18dba98 100644
--- a/HACK.TXT
+++ b/HACK.TXT
@@ -9,7 +9,8 @@
 │   ├── PowerPC     <- PowerPC engine
 │   ├── Sparc       <- Sparc engine
 │   ├── SystemZ     <- SystemZ engine
-│   └── X86         <- X86 engine
+│   ├── X86         <- X86 engine
+│   └── XCore       <- XCore engine
 ├── bindings        <- all bindings are under this dir
 │   ├── java        <- Java bindings + test code
 │   ├── ocaml       <- Ocaml bindings + test code