1 // (C) Copyright John Maddock 2000.
2 // Use, modification and distribution are subject to the Boost Software License,
3 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
4 // http://www.boost.org/LICENSE_1_0.txt).
6 // See http://www.boost.org/libs/type_traits for most recent version including documentation.
8 #ifndef BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
9 #define BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
11 #include <boost/mpl/if.hpp>
12 #include <boost/preprocessor/list/for_each_i.hpp>
13 #include <boost/preprocessor/tuple/to_list.hpp>
14 #include <boost/preprocessor/cat.hpp>
15 #include <boost/preprocessor/list/transform.hpp>
16 #include <boost/preprocessor/list/append.hpp>
17 #include <boost/type_traits/alignment_of.hpp>
18 #include <boost/type_traits/is_pod.hpp>
19 #include <boost/static_assert.hpp>
20 #include <boost/config.hpp>
22 // should be the last #include
23 #include <boost/type_traits/detail/bool_trait_def.hpp>
28 # pragma warning(push)
29 # pragma warning(disable: 4121) // alignment is sensitive to packing
38 class alignment_dummy;
39 typedef void (*function_ptr)();
40 typedef int (alignment_dummy::*member_ptr);
41 typedef int (alignment_dummy::*member_function_ptr)();
43 #ifdef BOOST_HAS_LONG_LONG
44 #define BOOST_TT_ALIGNMENT_BASE_TYPES BOOST_PP_TUPLE_TO_LIST( \
46 char, short, int, long, ::boost::long_long_type, float, double, long double \
47 , void*, function_ptr, member_ptr, member_function_ptr))
49 #define BOOST_TT_ALIGNMENT_BASE_TYPES BOOST_PP_TUPLE_TO_LIST( \
51 char, short, int, long, float, double, long double \
52 , void*, function_ptr, member_ptr, member_function_ptr))
55 #define BOOST_TT_HAS_ONE_T(D,Data,T) boost::detail::has_one_T< T >
57 #define BOOST_TT_ALIGNMENT_STRUCT_TYPES \
58 BOOST_PP_LIST_TRANSFORM(BOOST_TT_HAS_ONE_T, \
60 BOOST_TT_ALIGNMENT_BASE_TYPES)
62 #define BOOST_TT_ALIGNMENT_TYPES \
63 BOOST_PP_LIST_APPEND(BOOST_TT_ALIGNMENT_BASE_TYPES, \
64 BOOST_TT_ALIGNMENT_STRUCT_TYPES)
67 // lower_alignment_helper --
69 // This template gets instantiated a lot, so use partial
70 // specialization when available to reduce the compiler burden.
72 #ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
73 template <bool found = true>
74 struct lower_alignment_helper_impl
76 template <std::size_t, class>
80 enum { value = true };
85 struct lower_alignment_helper_impl<false>
87 template <std::size_t target, class TestType>
89 : public mpl::if_c<(alignment_of<TestType>::value == target), TestType, char>
91 enum { value = (alignment_of<TestType>::value == target) };
95 template <bool found, std::size_t target, class TestType>
96 struct lower_alignment_helper
97 : public lower_alignment_helper_impl<found>::template apply<target,TestType>
101 template <bool found, std::size_t target, class TestType>
102 struct lower_alignment_helper
105 enum { value = true };
108 template <std::size_t target, class TestType>
109 struct lower_alignment_helper<false,target,TestType>
111 enum { value = (alignment_of<TestType>::value == target) };
112 typedef typename mpl::if_c<value, TestType, char>::type type;
116 #define BOOST_TT_CHOOSE_MIN_ALIGNMENT(R,P,I,T) \
117 typename lower_alignment_helper< \
118 BOOST_PP_CAT(found,I),target,T \
119 >::type BOOST_PP_CAT(t,I); \
121 BOOST_PP_CAT(found,BOOST_PP_INC(I)) \
122 = lower_alignment_helper<BOOST_PP_CAT(found,I),target,T >::value \
125 #define BOOST_TT_CHOOSE_T(R,P,I,T) T BOOST_PP_CAT(t,I);
127 template <typename T>
133 template <std::size_t target>
134 union lower_alignment
136 enum { found0 = false };
138 BOOST_PP_LIST_FOR_EACH_I(
139 BOOST_TT_CHOOSE_MIN_ALIGNMENT
141 , BOOST_TT_ALIGNMENT_TYPES
147 BOOST_PP_LIST_FOR_EACH_I(
150 , BOOST_TT_ALIGNMENT_TYPES
154 #undef BOOST_TT_ALIGNMENT_BASE_TYPES
155 #undef BOOST_TT_HAS_ONE_T
156 #undef BOOST_TT_ALIGNMENT_STRUCT_TYPES
157 #undef BOOST_TT_ALIGNMENT_TYPES
158 #undef BOOST_TT_CHOOSE_MIN_ALIGNMENT
159 #undef BOOST_TT_CHOOSE_T
161 template<std::size_t TAlign, std::size_t Align>
164 BOOST_STATIC_CONSTANT(bool,
165 value = (TAlign >= Align) & (TAlign % Align == 0)
169 #ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
170 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::max_align,true)
171 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<1> ,true)
172 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<2> ,true)
173 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<4> ,true)
174 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<8> ,true)
175 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<10> ,true)
176 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<16> ,true)
177 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<32> ,true)
180 } // namespace detail
182 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
183 template<std::size_t Align>
184 struct is_pod< ::boost::detail::lower_alignment<Align> >
186 BOOST_STATIC_CONSTANT(std::size_t, value = true);
190 // This alignment method originally due to Brian Parker, implemented by David
191 // Abrahams, and then ported here by Doug Gregor.
194 template <std::size_t Align>
195 class type_with_alignment_imp
197 typedef ::boost::detail::lower_alignment<Align> t1;
198 typedef typename mpl::if_c<
199 ::boost::detail::is_aligned< ::boost::alignment_of<t1>::value,Align >::value
201 , ::boost::detail::max_align
204 BOOST_STATIC_CONSTANT(std::size_t, found = alignment_of<align_t>::value);
206 BOOST_STATIC_ASSERT(found >= Align);
207 BOOST_STATIC_ASSERT(found % Align == 0);
210 typedef align_t type;
215 template <std::size_t Align>
216 class type_with_alignment
217 : public ::boost::detail::type_with_alignment_imp<Align>
221 #if defined(__GNUC__)
223 struct __attribute__((__aligned__(2))) a2 {};
224 struct __attribute__((__aligned__(4))) a4 {};
225 struct __attribute__((__aligned__(8))) a8 {};
226 struct __attribute__((__aligned__(16))) a16 {};
227 struct __attribute__((__aligned__(32))) a32 {};
228 struct __attribute__((__aligned__(64))) a64 {};
229 struct __attribute__((__aligned__(128))) a128 {};
232 template<> class type_with_alignment<1> { public: typedef char type; };
233 template<> class type_with_alignment<2> { public: typedef align::a2 type; };
234 template<> class type_with_alignment<4> { public: typedef align::a4 type; };
235 template<> class type_with_alignment<8> { public: typedef align::a8 type; };
236 template<> class type_with_alignment<16> { public: typedef align::a16 type; };
237 template<> class type_with_alignment<32> { public: typedef align::a32 type; };
238 template<> class type_with_alignment<64> { public: typedef align::a64 type; };
239 template<> class type_with_alignment<128> { public: typedef align::a128 type; };
242 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a2,true)
243 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a4,true)
244 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a8,true)
245 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a16,true)
246 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a32,true)
247 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a64,true)
248 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a128,true)
251 #if (defined(BOOST_MSVC) || (defined(BOOST_INTEL) && defined(_MSC_VER))) && _MSC_VER >= 1300
253 // MSVC supports types which have alignments greater than the normal
254 // maximum: these are used for example in the types __m64 and __m128
255 // to provide types with alignment requirements which match the SSE
256 // registers. Therefore we extend type_with_alignment<> to support
257 // such types, however, we have to be careful to use a builtin type
258 // whenever possible otherwise we break previously working code:
259 // see http://article.gmane.org/gmane.comp.lib.boost.devel/173011
260 // for an example and test case. Thus types like a8 below will
261 // be used *only* if the existing implementation can't provide a type
262 // with suitable alignment. This does mean however, that type_with_alignment<>
263 // may return a type which cannot be passed through a function call
264 // by value (and neither can any type containing such a type like
265 // Boost.Optional). However, this only happens when we have no choice
266 // in the matter because no other "ordinary" type is available.
269 struct __declspec(align(8)) a8 {
273 struct __declspec(align(16)) a16 {
277 struct __declspec(align(32)) a32 {
281 struct __declspec(align(64)) a64
286 struct __declspec(align(128)) a128 {
292 template<> class type_with_alignment<8>
295 ::boost::alignment_of<boost::detail::max_align>::value < 8,
297 boost::detail::type_with_alignment_imp<8> >::type t1;
299 typedef t1::type type;
301 template<> class type_with_alignment<16>
304 ::boost::alignment_of<boost::detail::max_align>::value < 16,
306 boost::detail::type_with_alignment_imp<16> >::type t1;
308 typedef t1::type type;
310 template<> class type_with_alignment<32>
313 ::boost::alignment_of<boost::detail::max_align>::value < 32,
315 boost::detail::type_with_alignment_imp<32> >::type t1;
317 typedef t1::type type;
319 template<> class type_with_alignment<64> {
321 ::boost::alignment_of<boost::detail::max_align>::value < 64,
323 boost::detail::type_with_alignment_imp<64> >::type t1;
325 typedef t1::type type;
327 template<> class type_with_alignment<128> {
329 ::boost::alignment_of<boost::detail::max_align>::value < 128,
331 boost::detail::type_with_alignment_imp<128> >::type t1;
333 typedef t1::type type;
337 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a8,true)
338 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a16,true)
339 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a32,true)
340 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a64,true)
341 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a128,true)
348 // Borland specific version, we have this for two reasons:
349 // 1) The version above doesn't always compile (with the new test cases for example)
350 // 2) Because of Borlands #pragma option we can create types with alignments that are
351 // greater that the largest aligned builtin type.
354 #pragma option push -a16
355 struct a2{ short s; };
357 struct a8{ double s; };
358 struct a16{ long double s; };
364 typedef ::boost::align::a16 max_align;
366 //#if ! BOOST_WORKAROUND(__CODEGEARC__, BOOST_TESTED_AT(0x610))
367 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a2,true)
368 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a4,true)
369 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a8,true)
370 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a16,true)
374 template <std::size_t N> struct type_with_alignment
376 // We should never get to here, but if we do use the maximally
378 // BOOST_STATIC_ASSERT(0);
379 typedef align::a16 type;
381 template <> struct type_with_alignment<1>{ typedef char type; };
382 template <> struct type_with_alignment<2>{ typedef align::a2 type; };
383 template <> struct type_with_alignment<4>{ typedef align::a4 type; };
384 template <> struct type_with_alignment<8>{ typedef align::a8 type; };
385 template <> struct type_with_alignment<16>{ typedef align::a16 type; };
392 # pragma warning(pop)
395 #include <boost/type_traits/detail/bool_trait_undef.hpp>
397 #endif // BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED