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Kokkos_Utilities.hpp
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Kokkos_Utilities.hpp
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/*
//@HEADER
// ************************************************************************
//
// Kokkos v. 2.0
// Copyright (2014) Sandia Corporation
//
// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
// the U.S. Government retains certain rights in this software.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// 3. Neither the name of the Corporation nor the names of the
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY SANDIA CORPORATION "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SANDIA CORPORATION OR THE
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Questions? Contact H. Carter Edwards (hcedwar@sandia.gov)
//
// ************************************************************************
//@HEADER
*/
#ifndef KOKKOS_CORE_IMPL_UTILITIES_HPP
#define KOKKOS_CORE_IMPL_UTILITIES_HPP
#include <Kokkos_Macros.hpp>
#include <cstdint>
#include <type_traits>
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
namespace Kokkos { namespace Impl {
// same as std::forward
// needed to allow perfect forwarding on the device
template <typename T>
KOKKOS_INLINE_FUNCTION
constexpr
T&& forward( typename std::remove_reference<T>::type& arg ) noexcept
{ return static_cast<T&&>(arg); }
template <typename T>
KOKKOS_INLINE_FUNCTION
constexpr
T&& forward( typename std::remove_reference<T>::type&& arg ) noexcept
{ return static_cast<T&&>(arg); }
// same as std::move
// needed to allowing moving on the device
template <typename T>
KOKKOS_INLINE_FUNCTION
constexpr
typename std::remove_reference<T>::type&& move( T&& arg ) noexcept
{ return static_cast<typename std::remove_reference<T>::type&&>(arg); }
// empty function to allow expanding a variadic argument pack
template<typename... Args>
KOKKOS_INLINE_FUNCTION
void expand_variadic(Args &&...) {}
//----------------------------------------
// C++14 integer sequence
template< typename T , T ... Ints >
struct integer_sequence {
using value_type = T ;
static constexpr std::size_t size() noexcept { return sizeof...(Ints); }
};
template< typename T , std::size_t N >
struct make_integer_sequence_helper ;
template< typename T , T N >
using make_integer_sequence =
typename make_integer_sequence_helper<T,N>::type ;
template< typename T >
struct make_integer_sequence_helper< T , 0 >
{ using type = integer_sequence<T> ; };
template< typename T >
struct make_integer_sequence_helper< T , 1 >
{ using type = integer_sequence<T,0> ; };
template< typename T >
struct make_integer_sequence_helper< T , 2 >
{ using type = integer_sequence<T,0,1> ; };
template< typename T >
struct make_integer_sequence_helper< T , 3 >
{ using type = integer_sequence<T,0,1,2> ; };
template< typename T >
struct make_integer_sequence_helper< T , 4 >
{ using type = integer_sequence<T,0,1,2,3> ; };
template< typename T >
struct make_integer_sequence_helper< T , 5 >
{ using type = integer_sequence<T,0,1,2,3,4> ; };
template< typename T >
struct make_integer_sequence_helper< T , 6 >
{ using type = integer_sequence<T,0,1,2,3,4,5> ; };
template< typename T >
struct make_integer_sequence_helper< T , 7 >
{ using type = integer_sequence<T,0,1,2,3,4,5,6> ; };
template< typename T >
struct make_integer_sequence_helper< T , 8 >
{ using type = integer_sequence<T,0,1,2,3,4,5,6,7> ; };
template< typename X , typename Y >
struct make_integer_sequence_concat ;
template< typename T , T ... x , T ... y >
struct make_integer_sequence_concat< integer_sequence<T,x...>
, integer_sequence<T,y...> >
{ using type = integer_sequence< T , x ... , (sizeof...(x)+y)... > ; };
template< typename T , std::size_t N >
struct make_integer_sequence_helper {
using type = typename make_integer_sequence_concat
< typename make_integer_sequence_helper< T , N/2 >::type
, typename make_integer_sequence_helper< T , N - N/2 >::type
>::type ;
};
//----------------------------------------
template <std::size_t... Indices>
using index_sequence = integer_sequence<std::size_t, Indices...>;
template< std::size_t N >
using make_index_sequence = make_integer_sequence< std::size_t, N>;
//----------------------------------------
template <unsigned I, typename IntegerSequence>
struct integer_sequence_at;
template <unsigned I, typename T, T h0, T... tail>
struct integer_sequence_at<I, integer_sequence<T, h0, tail...> >
: public integer_sequence_at<I-1u, integer_sequence<T,tail...> >
{
static_assert( 8 <= I , "Reasoning Error" );
static_assert( I < integer_sequence<T, h0, tail...>::size(), "Error: Index out of bounds");
};
template < typename T, T h0, T... tail>
struct integer_sequence_at<0u, integer_sequence<T,h0, tail...> >
{
using type = T;
static constexpr T value = h0;
};
template < typename T, T h0, T h1, T... tail>
struct integer_sequence_at<1u, integer_sequence<T, h0, h1, tail...> >
{
using type = T;
static constexpr T value = h1;
};
template < typename T, T h0, T h1, T h2, T... tail>
struct integer_sequence_at<2u, integer_sequence<T, h0, h1, h2, tail...> >
{
using type = T;
static constexpr T value = h2;
};
template < typename T, T h0, T h1, T h2, T h3, T... tail>
struct integer_sequence_at<3u, integer_sequence<T, h0, h1, h2, h3, tail...> >
{
using type = T;
static constexpr T value = h3;
};
template < typename T, T h0, T h1, T h2, T h3, T h4, T... tail>
struct integer_sequence_at<4u, integer_sequence<T, h0, h1, h2, h3, h4, tail...> >
{
using type = T;
static constexpr T value = h4;
};
template < typename T, T h0, T h1, T h2, T h3, T h4, T h5, T... tail>
struct integer_sequence_at<5u, integer_sequence<T, h0, h1, h2, h3, h4, h5, tail...> >
{
using type = T;
static constexpr T value = h5;
};
template < typename T, T h0, T h1, T h2, T h3, T h4, T h5, T h6, T... tail>
struct integer_sequence_at<6u, integer_sequence<T, h0, h1, h2, h3, h4, h5, h6, tail...> >
{
using type = T;
static constexpr T value = h6;
};
template < typename T, T h0, T h1, T h2, T h3, T h4, T h5, T h6, T h7, T... tail>
struct integer_sequence_at<7u, integer_sequence<T, h0, h1, h2, h3, h4, h5, h6, h7, tail...> >
{
using type = T;
static constexpr T value = h7;
};
//----------------------------------------
template <typename T>
constexpr
T at( const unsigned, integer_sequence<T> ) noexcept
{ return ~static_cast<T>(0); }
template <typename T, T h0, T... tail>
constexpr
T at( const unsigned i, integer_sequence<T, h0> ) noexcept
{ return i==0u ? h0 : ~static_cast<T>(0); }
template <typename T, T h0, T h1>
constexpr
T at( const unsigned i, integer_sequence<T, h0, h1> ) noexcept
{ return i==0u ? h0 :
i==1u ? h1 : ~static_cast<T>(0);
}
template <typename T, T h0, T h1, T h2>
constexpr
T at( const unsigned i, integer_sequence<T, h0, h1, h2> ) noexcept
{ return i==0u ? h0 :
i==1u ? h1 :
i==2u ? h2 : ~static_cast<T>(0);
}
template <typename T, T h0, T h1, T h2, T h3>
constexpr
T at( const unsigned i, integer_sequence<T, h0, h1, h2, h3> ) noexcept
{ return i==0u ? h0 :
i==1u ? h1 :
i==2u ? h2 :
i==3u ? h3 : ~static_cast<T>(0);
}
template <typename T, T h0, T h1, T h2, T h3, T h4>
constexpr
T at( const unsigned i, integer_sequence<T, h0, h1, h2, h3, h4> ) noexcept
{ return i==0u ? h0 :
i==1u ? h1 :
i==2u ? h2 :
i==3u ? h3 :
i==4u ? h4 : ~static_cast<T>(0);
}
template <typename T, T h0, T h1, T h2, T h3, T h4, T h5>
constexpr
T at( const unsigned i, integer_sequence<T, h0, h1, h2, h3, h4, h5> ) noexcept
{ return i==0u ? h0 :
i==1u ? h1 :
i==2u ? h2 :
i==3u ? h3 :
i==4u ? h4 :
i==5u ? h5 : ~static_cast<T>(0);
}
template <typename T, T h0, T h1, T h2, T h3, T h4, T h5, T h6>
constexpr
T at( const unsigned i, integer_sequence<T, h0, h1, h2, h3, h4, h5, h6> ) noexcept
{ return i==0u ? h0 :
i==1u ? h1 :
i==2u ? h2 :
i==3u ? h3 :
i==4u ? h4 :
i==5u ? h5 :
i==6u ? h6 : ~static_cast<T>(0);
}
template <typename T, T h0, T h1, T h2, T h3, T h4, T h5, T h6, T h7, T... tail>
constexpr
T at( const unsigned i, integer_sequence<T, h0, h1, h2, h3, h4, h5, h6, h7, tail...> ) noexcept
{ return i==0u ? h0 :
i==1u ? h1 :
i==2u ? h2 :
i==3u ? h3 :
i==4u ? h4 :
i==5u ? h5 :
i==6u ? h6 :
i==7u ? h7 : at(i-8u, integer_sequence<T, tail...>{} );
}
//----------------------------------------
template < typename IntegerSequence
, typename ResultSequence = integer_sequence<typename IntegerSequence::value_type>
>
struct reverse_integer_sequence_helper;
template <typename T, T h0, T... tail, T... results>
struct reverse_integer_sequence_helper< integer_sequence<T, h0, tail...>, integer_sequence<T, results...> >
: public reverse_integer_sequence_helper< integer_sequence<T, tail...>, integer_sequence<T, h0, results...> >
{};
template <typename T, T... results>
struct reverse_integer_sequence_helper< integer_sequence<T>, integer_sequence<T, results...> >
{
using type = integer_sequence<T, results...>;
};
template <typename IntegerSequence>
using reverse_integer_sequence = typename reverse_integer_sequence_helper<IntegerSequence>::type;
//----------------------------------------
template < typename IntegerSequence
, typename Result
, typename ResultSequence = integer_sequence<typename IntegerSequence::value_type>
>
struct exclusive_scan_integer_sequence_helper;
template <typename T, T h0, T... tail, typename Result, T... results>
struct exclusive_scan_integer_sequence_helper
< integer_sequence<T, h0, tail...>
, Result
, integer_sequence<T, results...> >
: public exclusive_scan_integer_sequence_helper
< integer_sequence<T, tail...>
, std::integral_constant<T,Result::value+h0>
, integer_sequence<T, 0, (results+h0)...> >
{};
template <typename T, typename Result, T... results>
struct exclusive_scan_integer_sequence_helper
< integer_sequence<T>, Result, integer_sequence<T, results...> >
{
using type = integer_sequence<T, results...>;
static constexpr T value = Result::value ;
};
template <typename IntegerSequence>
struct exclusive_scan_integer_sequence
{
using value_type = typename IntegerSequence::value_type;
using helper =
exclusive_scan_integer_sequence_helper
< reverse_integer_sequence<IntegerSequence>
, std::integral_constant< value_type , 0 >
> ;
using type = typename helper::type ;
static constexpr value_type value = helper::value ;
};
//----------------------------------------
template < typename IntegerSequence
, typename Result
, typename ResultSequence = integer_sequence<typename IntegerSequence::value_type>
>
struct inclusive_scan_integer_sequence_helper;
template <typename T, T h0, T... tail, typename Result, T... results>
struct inclusive_scan_integer_sequence_helper
< integer_sequence<T, h0, tail...>
, Result
, integer_sequence<T, results...> >
: public inclusive_scan_integer_sequence_helper
< integer_sequence<T, tail...>
, std::integral_constant<T,Result::value+h0>
, integer_sequence<T, h0, (results+h0)...> >
{};
template <typename T, typename Result, T... results>
struct inclusive_scan_integer_sequence_helper
< integer_sequence<T>, Result, integer_sequence<T, results...> >
{
using type = integer_sequence<T, results...>;
static constexpr T value = Result::value ;
};
template <typename IntegerSequence>
struct inclusive_scan_integer_sequence
{
using value_type = typename IntegerSequence::value_type;
using helper =
inclusive_scan_integer_sequence_helper
< reverse_integer_sequence<IntegerSequence>
, std::integral_constant< value_type , 0 >
> ;
using type = typename helper::type ;
static constexpr value_type value = helper::value ;
};
}} // namespace Kokkos::Impl
#endif //KOKKOS_CORE_IMPL_UTILITIES_HPP

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