+/* Bitstring library.
+ * Copyright (C) 2008 Red Hat Inc., Richard W.M. Jones
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version,
+ * with the OCaml linking exception described in COPYING.LIB.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * $Id: bitstring.ml 146 2008-08-20 16:58:33Z richard.wm.jones $
+ */
+
+/* This file contains hand-coded, optimized C implementations of
+ * certain very frequently used functions.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <caml/mlvalues.h>
+#include <caml/fail.h>
+
+/* Return a mask of 0-31 bits wide. */
+CAMLprim value
+ocaml_bitstring_I_mask (value bitsv)
+{
+ int bits = Int_val (bitsv);
+
+ if (bits <= 31)
+ return Val_int ((1 << bits) - 1);
+ else
+ caml_invalid_argument ("Bitstring.I.mask");
+}