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lammps/lib/kokkos/core/src/impl/Kokkos_Traits.hpp
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Kokkos_Traits.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 KOKKOSTRAITS_HPP
#define KOKKOSTRAITS_HPP
#include <stddef.h>
#include <stdint.h>
#include <Kokkos_Macros.hpp>
namespace Kokkos {
namespace Impl {
//----------------------------------------------------------------------------
// Help with C++11 variadic argument packs
template< unsigned I , class ... Args >
struct variadic_type { typedef void type ; };
template< class T , class ... Args >
struct variadic_type< 0 , T , Args ... >
{ typedef T type ; };
template< unsigned I , class T , class ... Args >
struct variadic_type< I , T , Args ... >
{ typedef typename variadic_type< I - 1 , Args ... >::type type ; };
//----------------------------------------------------------------------------
/* C++11 conformal compile-time type traits utilities.
* Prefer to use C++11 when portably available.
*/
//----------------------------------------------------------------------------
// C++11 Helpers:
template < class T , T v >
struct integral_constant
{
// Declaration of 'static const' causes an unresolved linker symbol in debug
// static const T value = v ;
enum { value = T(v) };
typedef T value_type;
typedef integral_constant<T,v> type;
KOKKOS_INLINE_FUNCTION operator T() { return v ; }
};
typedef integral_constant<bool,false> false_type ;
typedef integral_constant<bool,true> true_type ;
//----------------------------------------------------------------------------
// C++11 Type relationships:
template< class X , class Y > struct is_same : public false_type {};
template< class X > struct is_same<X,X> : public true_type {};
//----------------------------------------------------------------------------
// C++11 Type properties:
template <typename T> struct is_const : public false_type {};
template <typename T> struct is_const<const T> : public true_type {};
template <typename T> struct is_const<const T & > : public true_type {};
template <typename T> struct is_array : public false_type {};
template <typename T> struct is_array< T[] > : public true_type {};
template <typename T, unsigned N > struct is_array< T[N] > : public true_type {};
//----------------------------------------------------------------------------
// C++11 Type transformations:
template <typename T> struct remove_const { typedef T type; };
template <typename T> struct remove_const<const T> { typedef T type; };
template <typename T> struct remove_const<const T & > { typedef T & type; };
template <typename T> struct add_const { typedef const T type; };
template <typename T> struct add_const<T & > { typedef const T & type; };
template <typename T> struct add_const<const T> { typedef const T type; };
template <typename T> struct add_const<const T & > { typedef const T & type; };
template <typename T> struct remove_reference { typedef T type ; };
template <typename T> struct remove_reference< T & > { typedef T type ; };
template <typename T> struct remove_reference< const T & > { typedef const T type ; };
template <typename T> struct remove_extent { typedef T type ; };
template <typename T> struct remove_extent<T[]> { typedef T type ; };
template <typename T, unsigned N > struct remove_extent<T[N]> { typedef T type ; };
//----------------------------------------------------------------------------
// C++11 Other type generators:
template< bool , class T , class F >
struct condition { typedef F type ; };
template< class T , class F >
struct condition<true,T,F> { typedef T type ; };
template< bool , class = void >
struct enable_if ;
template< class T >
struct enable_if< true , T > { typedef T type ; };
//----------------------------------------------------------------------------
} // namespace Impl
} // namespace Kokkos
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
// Other traits
namespace Kokkos {
namespace Impl {
//----------------------------------------------------------------------------
template< class , class T = void >
struct enable_if_type { typedef T type ; };
//----------------------------------------------------------------------------
template< bool B >
struct bool_ : public integral_constant<bool,B> {};
template< unsigned I >
struct unsigned_ : public integral_constant<unsigned,I> {};
template< int I >
struct int_ : public integral_constant<int,I> {};
typedef bool_<true> true_;
typedef bool_<false> false_;
//----------------------------------------------------------------------------
// if_
template < bool Cond , typename TrueType , typename FalseType>
struct if_c
{
enum { value = Cond };
typedef FalseType type;
typedef typename remove_const<
typename remove_reference<type>::type >::type value_type ;
typedef typename add_const<value_type>::type const_value_type ;
static KOKKOS_INLINE_FUNCTION
const_value_type & select( const_value_type & v ) { return v ; }
static KOKKOS_INLINE_FUNCTION
value_type & select( value_type & v ) { return v ; }
template< class T >
static KOKKOS_INLINE_FUNCTION
value_type & select( const T & ) { value_type * ptr(0); return *ptr ; }
template< class T >
static KOKKOS_INLINE_FUNCTION
const_value_type & select( const T & , const_value_type & v ) { return v ; }
template< class T >
static KOKKOS_INLINE_FUNCTION
value_type & select( const T & , value_type & v ) { return v ; }
};
template <typename TrueType, typename FalseType>
struct if_c< true , TrueType , FalseType >
{
enum { value = true };
typedef TrueType type;
typedef typename remove_const<
typename remove_reference<type>::type >::type value_type ;
typedef typename add_const<value_type>::type const_value_type ;
static KOKKOS_INLINE_FUNCTION
const_value_type & select( const_value_type & v ) { return v ; }
static KOKKOS_INLINE_FUNCTION
value_type & select( value_type & v ) { return v ; }
template< class T >
static KOKKOS_INLINE_FUNCTION
value_type & select( const T & ) { value_type * ptr(0); return *ptr ; }
template< class F >
static KOKKOS_INLINE_FUNCTION
const_value_type & select( const_value_type & v , const F & ) { return v ; }
template< class F >
static KOKKOS_INLINE_FUNCTION
value_type & select( value_type & v , const F & ) { return v ; }
};
template< typename TrueType >
struct if_c< false , TrueType , void >
{
enum { value = false };
typedef void type ;
typedef void value_type ;
};
template< typename FalseType >
struct if_c< true , void , FalseType >
{
enum { value = true };
typedef void type ;
typedef void value_type ;
};
template <typename Cond, typename TrueType, typename FalseType>
struct if_ : public if_c<Cond::value, TrueType, FalseType> {};
//----------------------------------------------------------------------------
// Allows aliased types:
template< typename T >
struct is_integral : public integral_constant< bool ,
(
std::is_same< T , char >::value ||
std::is_same< T , unsigned char >::value ||
std::is_same< T , short int >::value ||
std::is_same< T , unsigned short int >::value ||
std::is_same< T , int >::value ||
std::is_same< T , unsigned int >::value ||
std::is_same< T , long int >::value ||
std::is_same< T , unsigned long int >::value ||
std::is_same< T , long long int >::value ||
std::is_same< T , unsigned long long int >::value ||
std::is_same< T , int8_t >::value ||
std::is_same< T , int16_t >::value ||
std::is_same< T , int32_t >::value ||
std::is_same< T , int64_t >::value ||
std::is_same< T , uint8_t >::value ||
std::is_same< T , uint16_t >::value ||
std::is_same< T , uint32_t >::value ||
std::is_same< T , uint64_t >::value
)>
{};
//----------------------------------------------------------------------------
// These 'constexpr'functions can be used as
// both regular functions and meta-function.
/**\brief There exists integral 'k' such that N = 2^k */
KOKKOS_INLINE_FUNCTION
constexpr bool is_integral_power_of_two( const size_t N )
{ return ( 0 < N ) && ( 0 == ( N & ( N - 1 ) ) ); }
/**\brief Return integral 'k' such that N = 2^k, assuming valid. */
KOKKOS_INLINE_FUNCTION
constexpr unsigned integral_power_of_two_assume_valid( const size_t N )
{ return N == 1 ? 0 : 1 + integral_power_of_two_assume_valid( N >> 1 ); }
/**\brief Return integral 'k' such that N = 2^k, if exists.
* If does not exist return ~0u.
*/
KOKKOS_INLINE_FUNCTION
constexpr unsigned integral_power_of_two( const size_t N )
{ return is_integral_power_of_two(N) ? integral_power_of_two_assume_valid(N) : ~0u ; }
//----------------------------------------------------------------------------
template < size_t N >
struct is_power_of_two
{
enum type { value = (N > 0) && !(N & (N-1)) };
};
template < size_t N , bool OK = is_power_of_two<N>::value >
struct power_of_two ;
template < size_t N >
struct power_of_two<N,true>
{
enum type { value = 1+ power_of_two<(N>>1),true>::value };
};
template <>
struct power_of_two<2,true>
{
enum type { value = 1 };
};
template <>
struct power_of_two<1,true>
{
enum type { value = 0 };
};
/** \brief If power of two then return power,
* otherwise return ~0u.
*/
static KOKKOS_FORCEINLINE_FUNCTION
unsigned power_of_two_if_valid( const unsigned N )
{
unsigned p = ~0u ;
if ( N && ! ( N & ( N - 1 ) ) ) {
#if defined( __CUDA_ARCH__ ) && defined( KOKKOS_HAVE_CUDA )
p = __ffs(N) - 1 ;
#elif defined( __GNUC__ ) || defined( __GNUG__ )
p = __builtin_ffs(N) - 1 ;
#elif defined( __INTEL_COMPILER )
p = _bit_scan_forward(N);
#else
p = 0 ;
for ( unsigned j = 1 ; ! ( N & j ) ; j <<= 1 ) { ++p ; }
#endif
}
return p ;
}
//----------------------------------------------------------------------------
template< typename T , T v , bool NonZero = ( v != T(0) ) >
struct integral_nonzero_constant
{
// Declaration of 'static const' causes an unresolved linker symbol in debug
// static const T value = v ;
enum { value = T(v) };
typedef T value_type ;
typedef integral_nonzero_constant<T,v> type ;
KOKKOS_INLINE_FUNCTION integral_nonzero_constant( const T & ) {}
};
template< typename T , T zero >
struct integral_nonzero_constant<T,zero,false>
{
const T value ;
typedef T value_type ;
typedef integral_nonzero_constant<T,0> type ;
KOKKOS_INLINE_FUNCTION integral_nonzero_constant( const T & v ) : value(v) {}
};
//----------------------------------------------------------------------------
template < class C > struct is_integral_constant : public false_
{
typedef void integral_type ;
enum { integral_value = 0 };
};
template < typename T , T v >
struct is_integral_constant< integral_constant<T,v> > : public true_
{
typedef T integral_type ;
enum { integral_value = v };
};
} // namespace Impl
} // namespace Kokkos
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
#endif /* #ifndef KOKKOSTRAITS_HPP */
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