[Boost-commit] svn:boost r63786 - in sandbox/SOC/2010/bits_and_ints: boost/integer libs/integer/test

Subject: [Boost-commit] svn:boost r63786 - in sandbox/SOC/2010/bits_and_ints: boost/integer libs/integer/test
From: muriloufg_at_[hidden]
Date: 2010-07-09 14:44:58

Author: murilov
Date: 2010-07-09 14:44:56 EDT (Fri, 09 Jul 2010)
New Revision: 63786
URL: http://svn.boost.org/trac/boost/changeset/63786

Log:
Added static_safe_avg<> and mpl::safe_avg<> metafunctions
Added:
   sandbox/SOC/2010/bits_and_ints/boost/integer/static_safe_avg.hpp   (contents, props changed)
   sandbox/SOC/2010/bits_and_ints/libs/integer/test/safe_avg_test.cpp   (contents, props changed)
Text files modified: 
   sandbox/SOC/2010/bits_and_ints/libs/integer/test/Jamfile.v2                    |     1 +                                       
   sandbox/SOC/2010/bits_and_ints/libs/integer/test/clear_least_bit_set_test.cpp  |     2 +-                                      
   sandbox/SOC/2010/bits_and_ints/libs/integer/test/count_trailing_zeros_test.cpp |     2 +-                                      
   3 files changed, 3 insertions(+), 2 deletions(-)

Added: sandbox/SOC/2010/bits_and_ints/boost/integer/static_safe_avg.hpp
==============================================================================
--- (empty file)
+++ sandbox/SOC/2010/bits_and_ints/boost/integer/static_safe_avg.hpp	2010-07-09 14:44:56 EDT (Fri, 09 Jul 2010)
@@ -0,0 +1,58 @@
+//  Boost integer/static_safe_avg.hpp header file  ------------------------------//
+
+//  (C) Copyright Murilo Adriano Vasconcelos 2010.
+//  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 updates, documentation, and revision history. 
+
+#ifndef BOOST_STATIC_SAFE_AVG_INCLUDED
+#define BOOST_STATIC_SAFE_AVG_INCLUDED
+
+#include <boost/mpl/and.hpp>
+#include <boost/mpl/integral_c.hpp>
+#include <boost/utility/enable_if.hpp>
+#include <boost/type_traits/is_integral.hpp>
+#include <boost/integer/is_integral_constant.hpp>
+
+namespace boost {
+	
+/*
+ *	Given two constant values x and y, the (floor of the) average normally
+ *		would be computed by (x+y)/2 unfortunately, 
+ *		this can yield incorrect results due to overflow.
+ *	
+ *	`static_safe_avg<T, x, y>::value' and mpl::safe_avg<IC1, IC2>::value ensures 
+ *		that no overflow will happen even if (x+y) overflows the range of T.
+ */
+	
+namespace mpl {
+
+template <typename IC1, typename IC2, 
+	class Enable = typename enable_if< 
+		and_< 
+			is_integral_constant<IC1>, 
+			is_integral_constant<IC2> 
+		> 
+	>::type
+>
+struct safe_avg : integral_c<
+	typename IC1::value_type, 
+	((IC1::value & IC2::value) + ((IC1::value ^ IC2::value) >> 1))
+>
+{};
+
+}
+
+template <typename T, T Value1, T Value2, 
+	class Enable = typename enable_if< is_integral<T> >::type>
+struct static_safe_avg : mpl::safe_avg< 
+	mpl::integral_c<T, Value1>, 
+	mpl::integral_c<T, Value2> 
+>
+{};
+
+} // boost
+
+#endif

Modified: sandbox/SOC/2010/bits_and_ints/libs/integer/test/Jamfile.v2
==============================================================================
--- sandbox/SOC/2010/bits_and_ints/libs/integer/test/Jamfile.v2	(original)
+++ sandbox/SOC/2010/bits_and_ints/libs/integer/test/Jamfile.v2	2010-07-09 14:44:56 EDT (Fri, 09 Jul 2010)
@@ -24,6 +24,7 @@
                 [ run pop_count_test.cpp ]
                 [ run count_trailing_zeros_test.cpp ]
                 [ run clear_least_bit_set_test.cpp ]
+		[ run safe_avg_test.cpp ]
         [ compile cstdint_include_test.cpp ]
         [ compile integer_traits_include_test.cpp ]
         [ compile integer_include_test.cpp ]

Modified: sandbox/SOC/2010/bits_and_ints/libs/integer/test/clear_least_bit_set_test.cpp
==============================================================================
--- sandbox/SOC/2010/bits_and_ints/libs/integer/test/clear_least_bit_set_test.cpp	(original)
+++ sandbox/SOC/2010/bits_and_ints/libs/integer/test/clear_least_bit_set_test.cpp	2010-07-09 14:44:56 EDT (Fri, 09 Jul 2010)
@@ -20,7 +20,7 @@
 // Main testing function
 int main(int, char* [])
 {    
-	std::cout << "Doing tests on pop_count functions." << std::endl;
+	std::cout << "Doing tests on clear_least_bit_set functions." << std::endl;
         
         CLEAR_LEAST_BIT_SET_TEST(0x0, 0);
         CLEAR_LEAST_BIT_SET_TEST(0x1, 0);

Modified: sandbox/SOC/2010/bits_and_ints/libs/integer/test/count_trailing_zeros_test.cpp
==============================================================================
--- sandbox/SOC/2010/bits_and_ints/libs/integer/test/count_trailing_zeros_test.cpp	(original)
+++ sandbox/SOC/2010/bits_and_ints/libs/integer/test/count_trailing_zeros_test.cpp	2010-07-09 14:44:56 EDT (Fri, 09 Jul 2010)
@@ -20,7 +20,7 @@
 // Main testing function
 int main(int, char* [])
 {    
-	std::cout << "Doing tests on pop_count functions." << std::endl;
+	std::cout << "Doing tests on count_trailing_zeros functions." << std::endl;
         
         COUNT_ZEROS_TEST(0xF00000000, 32);
         COUNT_ZEROS_TEST(0x1, 0);

Added: sandbox/SOC/2010/bits_and_ints/libs/integer/test/safe_avg_test.cpp
==============================================================================
--- (empty file)
+++ sandbox/SOC/2010/bits_and_ints/libs/integer/test/safe_avg_test.cpp	2010-07-09 14:44:56 EDT (Fri, 09 Jul 2010)
@@ -0,0 +1,37 @@
+//  Boost safe_avg_test.hpp test program  --------------------------------------//
+
+//  (C) Copyright Murilo Adriano Vasconcelos 2010.
+//  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
+
+#include <boost/detail/lightweight_test.hpp>
+#include <boost/integer/safe_avg.hpp>
+#include <boost/integer/static_safe_avg.hpp>
+#include <boost/mpl/integral_c.hpp>
+
+#include <iostream> 
+
+#define SAFE_AVG_TEST(x, y, z) \
+BOOST_TEST((::boost::safe_avg(x, y) == z)); \
+BOOST_TEST(((::boost::mpl::safe_avg< ::boost::mpl::integral_c<int, x>, ::boost::mpl::integral_c<int, y> >::value) == z))
+
+
+// Main testing function
+int main(int, char* [])
+{    
+	std::cout << "Doing tests on safe_avg functions." << std::endl;
+	
+	SAFE_AVG_TEST(0, 0, 0);
+	SAFE_AVG_TEST(0, 1, 0);
+	SAFE_AVG_TEST(1, 1, 1);
+	SAFE_AVG_TEST(1, 2, 1);
+	SAFE_AVG_TEST(3, 1, 2);
+	SAFE_AVG_TEST(1000, 200, 600);
+	SAFE_AVG_TEST(1000000000, 2000000000, 1500000000);
+	SAFE_AVG_TEST(2000000000, 2000000000, 2000000000);
+	SAFE_AVG_TEST(-1000000000, 2000000000, 500000000);
+	SAFE_AVG_TEST(-2000000000, -2000000000, -2000000000);
+	
+	return boost::report_errors();
+}