82 lines
2.6 KiB
C++
82 lines
2.6 KiB
C++
//============================================================================
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// Copyright (c) Kitware, Inc.
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// All rights reserved.
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// See LICENSE.txt for details.
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// This software is distributed WITHOUT ANY WARRANTY; without even
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// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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// PURPOSE. See the above copyright notice for more information.
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//
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// Copyright 2014 Sandia Corporation.
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// Copyright 2014 UT-Battelle, LLC.
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// Copyright 2014 Los Alamos National Security.
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//
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// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
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// the U.S. Government retains certain rights in this software.
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//
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// Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
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// Laboratory (LANL), the U.S. Government retains certain rights in
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// this software.
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//============================================================================
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#ifndef vtk_m_internal_IntegerSequence_h
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#define vtk_m_internal_IntegerSequence_h
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#include <cstdlib>
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namespace vtkm {
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namespace internal {
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/// \brief A container of unsigned integers
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///
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/// C++11 Doesn't provide an IntegerSequence class and helper constructor
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// So we need to roll our own. This class has been tested up to 512 elements.
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//
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template<int...> struct IntegerSequence{};
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namespace detail {
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template<int N, int... Is> //unroll in blocks of 4
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struct MakeSeq : MakeSeq<N-4, N-3, N-2, N-1, N, Is...> {};
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template<int... Is>
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struct MakeSeq<0,1,2,3,Is...> //termination case
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{ using type = IntegerSequence<0,1,2,3,Is...>; };
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template<int Mod, int N>
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struct PreMakeSeq : MakeSeq<N-3, N-2, N-1, N> {};
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template<int N> //specialization for value +1 to divisible by 4
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struct PreMakeSeq<1,N> : MakeSeq<N> {};
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template<int N> //specialization for value +2 to divisible by 4
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struct PreMakeSeq<2,N> : MakeSeq<N-1,N> {};
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template<int N> //specialization for value +3 to divisible by 4
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struct PreMakeSeq<3,N> : MakeSeq<N-2,N-1,N> {};
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template<> //specialization for 4
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struct PreMakeSeq<4,3> { using type = IntegerSequence<0,1,2,3>; };
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template<> //specialization for 3
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struct PreMakeSeq<3,2> { using type = IntegerSequence<0,1,2>; };
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template<> //specialization for 2
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struct PreMakeSeq<2,1> { using type = IntegerSequence<0,1>; };
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template<> //specialization for 1
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struct PreMakeSeq<1,0> { using type = IntegerSequence<0>; };
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template<> //specialization for 0
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struct PreMakeSeq<0,-1> { using type = IntegerSequence<>; };
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} //namespace detail
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/// \brief A helper method to create an Integer sequence of 0...N-1.
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template<int N>
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struct MakeIntegerSequence : detail::PreMakeSeq<N%4,N-1> {};
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}
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}
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#endif //vtk_m_internal_IntegerSequence_h
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