Tpetra_Details_getGraphDiagOffsets_def.hpp

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// @HEADER
// *****************************************************************************
//          Tpetra: Templated Linear Algebra Services Package
//
// Copyright 2008 NTESS and the Tpetra contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

#ifndef TPETRA_DETAILS_GETGRAPHDIAGOFFSETS_DEF_HPP
#define TPETRA_DETAILS_GETGRAPHDIAGOFFSETS_DEF_HPP


#include "Tpetra_Details_OrdinalTraits.hpp"
#include "Tpetra_Map.hpp"
#include "KokkosSparse_findRelOffset.hpp"

namespace Tpetra {
namespace Details {
namespace Impl {

template<class LO,
         class GO,
         class Node,
         class DiagOffsetType>
GetGraphDiagOffsets<LO, GO, Node, DiagOffsetType>::
GetGraphDiagOffsets (const diag_offsets_type& diagOffsets,
                     const local_map_type& lclRowMap,
                     const local_map_type& lclColMap,
                     const row_offsets_type& ptr,
                     const lcl_col_inds_type& ind,
                     const bool isSorted) :
  diagOffsets_ (diagOffsets),
  lclRowMap_ (lclRowMap),
  lclColMap_ (lclColMap),
  ptr_ (ptr),
  ind_ (ind),
  isSorted_ (isSorted)
{
  typedef typename device_type::execution_space execution_space;
  typedef Kokkos::RangePolicy<execution_space, LO> policy_type;

  const LO lclNumRows = lclRowMap.getLocalNumElements ();
  policy_type range (0, lclNumRows);
  Kokkos::parallel_for (range, *this);
}

template<class LO,
         class GO,
         class Node,
         class DiagOffsetType>
KOKKOS_FUNCTION void
GetGraphDiagOffsets<LO, GO, Node, DiagOffsetType>::
operator() (const LO& lclRowInd) const
{
  const size_t STINV =
    Tpetra::Details::OrdinalTraits<diag_offset_type>::invalid ();
  const GO gblRowInd = lclRowMap_.getGlobalElement (lclRowInd);
  const GO gblColInd = gblRowInd;
  const LO lclColInd = lclColMap_.getLocalElement (gblColInd);

  if (lclColInd == Tpetra::Details::OrdinalTraits<LO>::invalid ()) {
    diagOffsets_[lclRowInd] = STINV;
  }
  else {
    // Could be empty, but that's OK.
    const LO numEnt = ptr_[lclRowInd+1] - ptr_[lclRowInd];
    // std::pair doesn't have its methods marked as device
    // functions, so we have to use Kokkos::pair.
    auto lclColInds =
      Kokkos::subview (ind_, Kokkos::make_pair (ptr_[lclRowInd],
                                                ptr_[lclRowInd+1]));
    using ::KokkosSparse::findRelOffset;
    const LO diagOffset =
      findRelOffset<LO, lcl_col_inds_type> (lclColInds, numEnt,
                                            lclColInd, 0, isSorted_);
    diagOffsets_[lclRowInd] = (diagOffset == numEnt) ? STINV :
      static_cast<diag_offset_type> (diagOffset);
  }
}

} // namespace Impl
} // namespace Details
} // namespace Tpetra

// Explicit template instantiation macro for
// Tpetra::Details::Impl::GetGraphDiagOffsets.  NOT FOR USERS!!!  Must
// be used inside the Tpetra namespace.
#define TPETRA_DETAILS_IMPL_GETGRAPHDIAGOFFSETS_INSTANT( LO, GO, NODE ) \
  template class Details::Impl::GetGraphDiagOffsets< LO, GO, NODE::device_type >;

#endif // TPETRA_DETAILS_GETGRAPHDIAGOFFSETS_DEF_HPP