diff --git a/sim/hei_user_defines.hpp b/sim/hei_user_defines.hpp
new file mode 100644
index 0000000..54c7344
--- /dev/null
+++ b/sim/hei_user_defines.hpp
@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include <assert.h>
+
+#define HEI_INF( ... ) \
+{ \
+  printf( "I> " __VA_ARGS__ ); \
+  printf( "\n" ); \
+}
+
+#define HEI_ERR( ... ) \
+{ \
+  printf( "E> " __VA_ARGS__ ); \
+  printf( "\n" ); \
+}
+
+#define HEI_ASSERT( expression ) \
+  assert( expression );
+