[Boost-commit] svn:boost r69961 - trunk/boost/random/detail

Subject: [Boost-commit] svn:boost r69961 - trunk/boost/random/detail
From: steven_at_[hidden]
Date: 2011-03-13 14:28:08

Author: steven_watanabe
Date: 2011-03-13 14:28:07 EDT (Sun, 13 Mar 2011)
New Revision: 69961
URL: http://svn.boost.org/trac/boost/changeset/69961

Log:
Add missing file.
Added:
   trunk/boost/random/detail/integer_log2.hpp   (contents, props changed)

Added: trunk/boost/random/detail/integer_log2.hpp
==============================================================================
--- (empty file)
+++ trunk/boost/random/detail/integer_log2.hpp	2011-03-13 14:28:07 EDT (Sun, 13 Mar 2011)
@@ -0,0 +1,59 @@
+/* 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: independent_bits.hpp 68822 2011-02-13 03:28:59Z steven_watanabe $
+ *
+ */
+
+#ifndef BOOST_RANDOM_DETAIL_INTEGER_LOG2_HPP
+#define BOOST_RANDOM_DETAIL_INTEGER_LOG2_HPP
+
+#include <boost/limits.hpp>
+#include <boost/pending/integer_log2.hpp>
+
+namespace boost {
+namespace random {
+namespace detail {
+
+template<int Shift>
+struct integer_log2_impl
+{
+    template<class T>
+    static int apply(T t, int accum)
+    {
+        int update = ((t >> Shift) != 0) * Shift;
+        return integer_log2_impl<Shift / 2>::apply(t >> update, accum + update);
+    }
+};
+
+template<>
+struct integer_log2_impl<1>
+{
+    template<class T>
+    static int apply(T t, int accum)
+    {
+        return int(t >> 1) + accum;
+    }
+};
+
+template<class T>
+inline 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