comparison DEPENDENCIES/generic/include/boost/heap/detail/ilog2.hpp @ 16:2665513ce2d3

Add boost headers

+// boost heap: integer log2
+//
+// Copyright (C) 2010 Tim Blechmann
+//
+// 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)
+
+#ifndef BOOST_HEAP_DETAIL_ILOG2_HPP
+#define BOOST_HEAP_DETAIL_ILOG2_HPP
+
+#include <string> // std::size_t
+
+namespace boost {
+namespace heap {
+namespace detail {
+
+template <typename IntType>
+struct log2
+{
+    IntType operator()(IntType value)
+    {
+        IntType l = 0;
+        while( (value >> l) > 1 )
+            ++l;
+        return l;
+    }
+};
+
+#ifdef __GNUC__
+template<>
+struct log2<unsigned int>
+{
+    unsigned int operator()(unsigned int value)
+    {
+        return sizeof(unsigned int)*8 - __builtin_clz(value - 1);
+    }
+};
+
+template<>
+struct log2<unsigned long>
+{
+    unsigned long operator()(unsigned long value)
+    {
+        return sizeof(unsigned long)*8 - __builtin_clzl(value - 1);
+    }
+};
+
+#endif
+
+} /* namespace detail */
+
+
+template <typename IntType>
+IntType log2(IntType value)
+{
+    detail::log2<IntType> fn;
+    return fn(value);
+}
+
+} /* namespace heap */
+} /* namespace boost */
+
+#endif /* BOOST_HEAP_DETAIL_ILOG2_HPP */