From c56e4674f81197c3dadfbadd87a122bbd4addc41 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Karlsson?= <Bjorn.Karlsson@readsoft.com>
Date: Wed, 19 Jun 2002 20:11:17 +0000
Subject: [PATCH] Update from Daryle

[SVN r14187]
---
 doc/static_log2.html                  |  5 +--
 include/boost/integer/static_log2.hpp | 52 ++++++++++++++++++++++++++-
 2 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/doc/static_log2.html b/doc/static_log2.html
index d3daab2..6764572 100644
--- a/doc/static_log2.html
+++ b/doc/static_log2.html
@@ -107,11 +107,12 @@ at compile-time) available.</p>
 <h2><a name="credits">Credits</a></h2>
 
 <p>The author of the Boost binary logarithm class template is <a
-href="../../../people/daryle_walker.html">Daryle Walker</a>.</p>
+href="../../../people/daryle_walker.html">Daryle Walker</a>.  Giovanni Bajo
+added support for compilers without partial template specialization.</p>
 
 <hr>
 
-<p>Revised October 1, 2001</p>
+<p>Revised May 14, 2002</p>
 
 <p>&copy; Copyright Daryle Walker 2001.  Permission to copy, use,
 modify, sell and distribute this document is granted provided this
diff --git a/include/boost/integer/static_log2.hpp b/include/boost/integer/static_log2.hpp
index 436250e..fed9d6c 100644
--- a/include/boost/integer/static_log2.hpp
+++ b/include/boost/integer/static_log2.hpp
@@ -12,9 +12,13 @@
 
 #include <boost/integer_fwd.hpp>  // self include
 
-#include <boost/config.hpp>  // for BOOST_STATIC_CONSTANT
+#include <boost/config.hpp>  // for BOOST_STATIC_CONSTANT, etc.
 #include <boost/limits.hpp>  // for std::numeric_limits
 
+#ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
+#include <boost/pending/ct_if.hpp>  // for boost::ct_if<>
+#endif
+
 
 namespace boost
 {
@@ -30,9 +34,22 @@ template < unsigned long Val, int Place = 0, int Index
  = std::numeric_limits<unsigned long>::digits >
     struct static_log2_helper_t;
 
+#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
+
 template < unsigned long Val, int Place >
     struct static_log2_helper_t< Val, Place, 1 >;
 
+#else
+
+template < int Place >
+    struct static_log2_helper_final_step;
+
+template < unsigned long Val, int Place = 0, int Index
+ = std::numeric_limits<unsigned long>::digits >
+    struct static_log2_helper_nopts_t;
+
+#endif
+
 // Recursively build the logarithm by examining the upper bits
 template < unsigned long Val, int Place, int Index >
 struct static_log2_helper_t
@@ -50,7 +67,11 @@ private:
      : Place );
     BOOST_STATIC_CONSTANT( int, new_index = Index - half_place );
 
+#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
     typedef static_log2_helper_t<new_val, new_place, new_index>  next_step_type;
+#else
+    typedef static_log2_helper_nopts_t<new_val, new_place, new_index>  next_step_type;
+#endif
 
 public:
     BOOST_STATIC_CONSTANT( int, value = next_step_type::value );
@@ -58,6 +79,8 @@ public:
 };  // boost::detail::static_log2_helper_t
 
 // Non-recursive case
+#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
+
 template < unsigned long Val, int Place >
 struct static_log2_helper_t< Val, Place, 1 >
 {
@@ -66,6 +89,33 @@ public:
 
 };  // boost::detail::static_log2_helper_t
 
+#else
+
+template < int Place >
+struct static_log2_helper_final_step
+{
+public:
+    BOOST_STATIC_CONSTANT( int, value = Place );
+
+};  // boost::detail::static_log2_helper_final_step
+
+template < unsigned long Val, int Place, int Index >
+struct static_log2_helper_nopts_t
+{
+private:
+    typedef static_log2_helper_t<Val, Place, Index>  recursive_step_type;
+    typedef static_log2_helper_final_step<Place>     final_step_type;
+
+    typedef typename ct_if<( Index != 1 ), recursive_step_type,
+     final_step_type>::type  next_step_type;
+
+public:
+    BOOST_STATIC_CONSTANT( int, value = next_step_type::value );
+
+};  // boost::detail::static_log2_helper_nopts_t
+
+#endif
+
 }  // namespace detail