boost/type_traits/type_with_alignment.hpp
// (C) Copyright John Maddock 2000.
// Use, modification and distribution are subject to 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/libs/type_traits for most recent version including documentation.
#ifndef BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
#define BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
#include <boost/mpl/if.hpp>
#include <boost/preprocessor/list/for_each_i.hpp>
#include <boost/preprocessor/tuple/to_list.hpp>
#include <boost/preprocessor/cat.hpp>
#include <boost/preprocessor/list/transform.hpp>
#include <boost/preprocessor/list/append.hpp>
#include <boost/type_traits/alignment_of.hpp>
#include <boost/type_traits/is_pod.hpp>
#include <boost/static_assert.hpp>
#include <boost/config.hpp>
// should be the last #include
#include <boost/type_traits/detail/bool_trait_def.hpp>
#include <cstddef>
#ifdef BOOST_MSVC
# pragma warning(push)
# pragma warning(disable: 4121) // alignment is sensitive to packing
#endif
namespace boost {
#ifndef __BORLANDC__
namespace detail {
class alignment_dummy;
typedef void (*function_ptr)();
typedef int (alignment_dummy::*member_ptr);
typedef int (alignment_dummy::*member_function_ptr)();
#ifdef BOOST_HAS_LONG_LONG
#define BOOST_TT_ALIGNMENT_BASE_TYPES BOOST_PP_TUPLE_TO_LIST( \
12, ( \
char, short, int, long, ::boost::long_long_type, float, double, long double \
, void*, function_ptr, member_ptr, member_function_ptr))
#else
#define BOOST_TT_ALIGNMENT_BASE_TYPES BOOST_PP_TUPLE_TO_LIST( \
11, ( \
char, short, int, long, float, double, long double \
, void*, function_ptr, member_ptr, member_function_ptr))
#endif
#define BOOST_TT_HAS_ONE_T(D,Data,T) boost::detail::has_one_T< T >
#define BOOST_TT_ALIGNMENT_STRUCT_TYPES \
BOOST_PP_LIST_TRANSFORM(BOOST_TT_HAS_ONE_T, \
X, \
BOOST_TT_ALIGNMENT_BASE_TYPES)
#define BOOST_TT_ALIGNMENT_TYPES \
BOOST_PP_LIST_APPEND(BOOST_TT_ALIGNMENT_BASE_TYPES, \
BOOST_TT_ALIGNMENT_STRUCT_TYPES)
//
// lower_alignment_helper --
//
// This template gets instantiated a lot, so use partial
// specialization when available to reduce the compiler burden.
//
#ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
template <bool found = true>
struct lower_alignment_helper_impl
{
template <std::size_t, class>
struct apply
{
typedef char type;
enum { value = true };
};
};
template <>
struct lower_alignment_helper_impl<false>
{
template <std::size_t target, class TestType>
struct apply
: mpl::if_c<(alignment_of<TestType>::value == target), TestType, char>
{
enum { value = (alignment_of<TestType>::value == target) };
};
};
template <bool found, std::size_t target, class TestType>
struct lower_alignment_helper
: lower_alignment_helper_impl<found>::template apply<target,TestType>
{
};
#else
template <bool found, std::size_t target, class TestType>
struct lower_alignment_helper
{
typedef char type;
enum { value = true };
};
template <std::size_t target, class TestType>
struct lower_alignment_helper<false,target,TestType>
{
enum { value = (alignment_of<TestType>::value == target) };
typedef typename mpl::if_c<value, TestType, char>::type type;
};
#endif
#define BOOST_TT_CHOOSE_MIN_ALIGNMENT(R,P,I,T) \
typename lower_alignment_helper< \
BOOST_PP_CAT(found,I),target,T \
>::type BOOST_PP_CAT(t,I); \
enum { \
BOOST_PP_CAT(found,BOOST_PP_INC(I)) \
= lower_alignment_helper<BOOST_PP_CAT(found,I),target,T >::value \
};
#define BOOST_TT_CHOOSE_T(R,P,I,T) T BOOST_PP_CAT(t,I);
template <typename T>
struct has_one_T
{
T data;
};
template <std::size_t target>
union lower_alignment
{
enum { found0 = false };
BOOST_PP_LIST_FOR_EACH_I(
BOOST_TT_CHOOSE_MIN_ALIGNMENT
, ignored
, BOOST_TT_ALIGNMENT_TYPES
)
};
union max_align
{
BOOST_PP_LIST_FOR_EACH_I(
BOOST_TT_CHOOSE_T
, ignored
, BOOST_TT_ALIGNMENT_TYPES
)
};
#undef BOOST_TT_ALIGNMENT_BASE_TYPES
#undef BOOST_TT_HAS_ONE_T
#undef BOOST_TT_ALIGNMENT_STRUCT_TYPES
#undef BOOST_TT_ALIGNMENT_TYPES
#undef BOOST_TT_CHOOSE_MIN_ALIGNMENT
#undef BOOST_TT_CHOOSE_T
template<std::size_t TAlign, std::size_t Align>
struct is_aligned
{
BOOST_STATIC_CONSTANT(bool,
value = (TAlign >= Align) & (TAlign % Align == 0)
);
};
#ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::max_align,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<1> ,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<2> ,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<4> ,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<8> ,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<10> ,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<16> ,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<32> ,true)
#endif
} // namespace detail
#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
template<std::size_t Align>
struct is_pod< ::boost::detail::lower_alignment<Align> >
{
BOOST_STATIC_CONSTANT(std::size_t, value = true);
};
#endif
// This alignment method originally due to Brian Parker, implemented by David
// Abrahams, and then ported here by Doug Gregor.
namespace detail{
template <std::size_t Align>
class type_with_alignment_imp
{
typedef ::boost::detail::lower_alignment<Align> t1;
typedef typename mpl::if_c<
::boost::detail::is_aligned< ::boost::alignment_of<t1>::value,Align >::value
, t1
, ::boost::detail::max_align
>::type align_t;
BOOST_STATIC_CONSTANT(std::size_t, found = alignment_of<align_t>::value);
BOOST_STATIC_ASSERT(found >= Align);
BOOST_STATIC_ASSERT(found % Align == 0);
public:
typedef align_t type;
};
}
template <std::size_t Align>
class type_with_alignment
: public ::boost::detail::type_with_alignment_imp<Align>
{
};
#if defined(__GNUC__)
namespace align {
struct __attribute__((__aligned__(2))) a2 {};
struct __attribute__((__aligned__(4))) a4 {};
struct __attribute__((__aligned__(8))) a8 {};
struct __attribute__((__aligned__(16))) a16 {};
struct __attribute__((__aligned__(32))) a32 {};
}
template<> class type_with_alignment<1> { public: typedef char type; };
template<> class type_with_alignment<2> { public: typedef align::a2 type; };
template<> class type_with_alignment<4> { public: typedef align::a4 type; };
template<> class type_with_alignment<8> { public: typedef align::a8 type; };
template<> class type_with_alignment<16> { public: typedef align::a16 type; };
template<> class type_with_alignment<32> { public: typedef align::a32 type; };
namespace detail {
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a2,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a4,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a8,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a16,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a32,true)
}
#endif
#if (defined(BOOST_MSVC) || (defined(BOOST_INTEL) && defined(_MSC_VER))) && _MSC_VER >= 1300
//
// MSVC supports types which have alignments greater than the normal
// maximum: these are used for example in the types __m64 and __m128
// to provide types with alignment requirements which match the SSE
// registers. Therefore we extend type_with_alignment<> to support
// such types, however, we have to be careful to use a builtin type
// whenever possible otherwise we break previously working code:
// see http://article.gmane.org/gmane.comp.lib.boost.devel/173011
// for an example and test case. Thus types like a8 below will
// be used *only* if the existing implementation can't provide a type
// with suitable alignment. This does mean however, that type_with_alignment<>
// may return a type which cannot be passed through a function call
// by value (and neither can any type containing such a type like
// Boost.Optional). However, this only happens when we have no choice
// in the matter because no other "ordinary" type is available.
//
namespace align {
struct __declspec(align(8)) a8 {
char m[8];
typedef a8 type;
};
struct __declspec(align(16)) a16 {
char m[16];
typedef a16 type;
};
struct __declspec(align(32)) a32 {
char m[32];
typedef a32 type;
};
struct __declspec(align(64)) a64
{
char m[64];
typedef a64 type;
};
struct __declspec(align(128)) a128 {
char m[128];
typedef a128 type;
};
}
template<> class type_with_alignment<8>
{
typedef mpl::if_c<
::boost::alignment_of<detail::max_align>::value < 8,
align::a8,
detail::type_with_alignment_imp<8> >::type t1;
public:
typedef t1::type type;
};
template<> class type_with_alignment<16>
{
typedef mpl::if_c<
::boost::alignment_of<detail::max_align>::value < 16,
align::a16,
detail::type_with_alignment_imp<16> >::type t1;
public:
typedef t1::type type;
};
template<> class type_with_alignment<32>
{
typedef mpl::if_c<
::boost::alignment_of<detail::max_align>::value < 32,
align::a32,
detail::type_with_alignment_imp<32> >::type t1;
public:
typedef t1::type type;
};
template<> class type_with_alignment<64> {
typedef mpl::if_c<
::boost::alignment_of<detail::max_align>::value < 64,
align::a64,
detail::type_with_alignment_imp<64> >::type t1;
public:
typedef t1::type type;
};
template<> class type_with_alignment<128> {
typedef mpl::if_c<
::boost::alignment_of<detail::max_align>::value < 128,
align::a128,
detail::type_with_alignment_imp<128> >::type t1;
public:
typedef t1::type type;
};
namespace detail {
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a8,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a16,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a32,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a64,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a128,true)
}
#endif
#else
//
// Borland specific version, we have this for two reasons:
// 1) The version above doesn't always compile (with the new test cases for example)
// 2) Because of Borlands #pragma option we can create types with alignments that are
// greater that the largest aligned builtin type.
namespace align{
#pragma option push -a16
struct a2{ short s; };
struct a4{ int s; };
struct a8{ double s; };
struct a16{ long double s; };
#pragma option pop
}
namespace detail {
typedef ::boost::align::a16 max_align;
//#if ! BOOST_WORKAROUND(__CODEGEARC__, BOOST_TESTED_AT(0x610))
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a2,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a4,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a8,true)
BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a16,true)
//#endif
}
template <std::size_t N> struct type_with_alignment
{
// We should never get to here, but if we do use the maximally
// aligned type:
// BOOST_STATIC_ASSERT(0);
typedef align::a16 type;
};
template <> struct type_with_alignment<1>{ typedef char type; };
template <> struct type_with_alignment<2>{ typedef align::a2 type; };
template <> struct type_with_alignment<4>{ typedef align::a4 type; };
template <> struct type_with_alignment<8>{ typedef align::a8 type; };
template <> struct type_with_alignment<16>{ typedef align::a16 type; };
#endif
} // namespace boost
#ifdef BOOST_MSVC
# pragma warning(pop)
#endif
#include <boost/type_traits/detail/bool_trait_undef.hpp>
#endif // BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED