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3rdparty/boost_1_81_0/boost/mpi/detail/offsets.hpp 1.76 KB
63e88f80   Hu Chunming   提交三方库
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  //          Copyright Alain Miniussi 2014.
  // Distributed under 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)
  
  // Authors: Alain Miniussi
  
  #ifndef BOOST_MPI_OFFSETS_HPP
  #define BOOST_MPI_OFFSETS_HPP
  
  #include <vector>
  #include <boost/mpi/config.hpp>
  #include <boost/mpi/communicator.hpp>
  
  namespace boost { namespace mpi {
  namespace detail {
  
  // Convert a sequence of sizes [S0..Sn] to a sequence displacement 
  // [O0..On] where O[0] = 0 and O[k+1] = O[k]+S[k].
  void BOOST_MPI_DECL sizes2offsets(int const* sizes, int* offsets, int n);
  
  // Same as size2offset(sizes.data(), offsets.data(), sizes.size())
  void BOOST_MPI_DECL sizes2offsets(std::vector<int> const& sizes, std::vector<int>& offsets);
  
  // Given a sequence of sizes (typically the number of records dispatched
  // to each process in a scater) and a sequence of displacements (typically the
  // slot index at with those record starts), convert the later to a number 
  // of skipped slots.
  void offsets2skipped(int const* sizes, int const* offsets, int* skipped, int n);
  
  // Reconstruct offsets from sizes assuming no padding.
  // Only takes place if on the root process and if 
  // displs are not already provided.
  // If memory was allocated, returns a pointer to it
  // otherwise null.
  int* make_offsets(communicator const& comm, int const* sizes, int const* displs, int root = -1);
  
  // Reconstruct skip slots from sizes and offsets.
  // Only takes place if on the root process and if 
  // displs are provided.
  // If memory was allocated, returns a pointer to it
  // otherwise null.
  int* make_skipped_slots(communicator const& comm, int const* sizes, int const* displs, int root = -1);
  
  }
  }}// end namespace boost::mpi
  
  #endif // BOOST_MPI_OFFSETS_HPP