Added boost header

test/external/boost/random/detail/integer_log2.hpp

@@ -0,0 +1,71 @@
+/* boost random/detail/integer_log2.hpp header file
+ *
+ * Copyright Steven Watanabe 2011
+ * 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)
+ *
+ * See http://www.boost.org for most recent version including documentation.
+ *
+ * $Id: integer_log2.hpp 73268 2011-07-21 07:49:59Z danieljames $
+ *
+ */
+
+#ifndef BOOST_RANDOM_DETAIL_INTEGER_LOG2_HPP
+#define BOOST_RANDOM_DETAIL_INTEGER_LOG2_HPP
+
+#include <boost/config.hpp>
+#include <boost/limits.hpp>
+#include <boost/pending/integer_log2.hpp>
+
+namespace boost {
+namespace random {
+namespace detail {
+
+#if !defined(BOOST_NO_CONSTEXPR)
+#define BOOST_RANDOM_DETAIL_CONSTEXPR constexpr
+#elif defined(BOOST_MSVC)
+#define BOOST_RANDOM_DETAIL_CONSTEXPR __forceinline
+#elif defined(__GNUC__) && __GNUC__ >= 4
+#define BOOST_RANDOM_DETAIL_CONSTEXPR __attribute__((const)) __attribute__((always_inline))
+#else
+#define BOOST_RANDOM_DETAIL_CONSTEXPR inline
+#endif
+
+template<int Shift>
+struct integer_log2_impl
+{
+    template<class T>
+    BOOST_RANDOM_DETAIL_CONSTEXPR static int apply(T t, int accum,
+            int update = 0)
+    {
+        return update = ((t >> Shift) != 0) * Shift,
+            integer_log2_impl<Shift / 2>::apply(t >> update, accum + update);
+    }
+};
+
+template<>
+struct integer_log2_impl<1>
+{
+    template<class T>
+    BOOST_RANDOM_DETAIL_CONSTEXPR static int apply(T t, int accum)
+    {
+        return int(t >> 1) + accum;
+    }
+};
+
+template<class T>
+BOOST_RANDOM_DETAIL_CONSTEXPR int integer_log2(T t)
+{
+    return integer_log2_impl<
+        ::boost::detail::max_pow2_less<
+            ::std::numeric_limits<T>::digits, 4
+        >::value
+    >::apply(t, 0);
+}
+
+} // namespace detail
+} // namespace random
+} // namespace boost
+
+#endif // BOOST_RANDOM_DETAIL_INTEGER_LOG2_HPP