Added boost header

test/external/boost/mpi/collectives/all_reduce.hpp

@@ -0,0 +1,102 @@
+// Copyright (C) 2005-2006 Douglas Gregor <doug.gregor -at- gmail.com>
+// Copyright (C) 2004 The Trustees of Indiana University
+
+// Use, modification and distribution is subject to 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: Douglas Gregor
+//            Andrew Lumsdaine
+
+// Message Passing Interface 1.1 -- Section 4.9.1. Reduce
+#ifndef BOOST_MPI_ALL_REDUCE_HPP
+#define BOOST_MPI_ALL_REDUCE_HPP
+
+// All-reduce falls back to reduce() + broadcast() in some cases.
+#include <boost/mpi/collectives/broadcast.hpp>
+#include <boost/mpi/collectives/reduce.hpp>
+
+namespace boost { namespace mpi {
+
+namespace detail {
+  /**********************************************************************
+   * Simple reduction with MPI_Allreduce                                *
+   **********************************************************************/
+  // We are reducing for a type that has an associated MPI
+  // datatype and operation, so we'll use MPI_Allreduce directly.
+  template<typename T, typename Op>
+  void
+  all_reduce_impl(const communicator& comm, const T* in_values, int n,
+                  T* out_values, Op /*op*/, mpl::true_ /*is_mpi_op*/,
+                  mpl::true_ /*is_mpi_datatype*/)
+  {
+    BOOST_MPI_CHECK_RESULT(MPI_Allreduce,
+                           (const_cast<T*>(in_values), out_values, n,
+                            boost::mpi::get_mpi_datatype<T>(*in_values),
+                            (is_mpi_op<Op, T>::op()), comm));
+  }
+
+  /**********************************************************************
+   * User-defined reduction with MPI_Allreduce                          *
+   **********************************************************************/
+  // We are reducing at the root for a type that has an associated MPI
+  // datatype but with a custom operation. We'll use MPI_Reduce
+  // directly, but we'll need to create an MPI_Op manually.
+  template<typename T, typename Op>
+  void
+  all_reduce_impl(const communicator& comm, const T* in_values, int n,
+                  T* out_values, Op op, mpl::false_ /*is_mpi_op*/,
+                  mpl::true_ /*is_mpi_datatype*/)
+  {
+    user_op<Op, T> mpi_op(op);
+    BOOST_MPI_CHECK_RESULT(MPI_Allreduce,
+                           (const_cast<T*>(in_values), out_values, n,
+                            boost::mpi::get_mpi_datatype<T>(*in_values),
+                            mpi_op.get_mpi_op(), comm));
+  }
+
+  /**********************************************************************
+   * User-defined, tree-based reduction for non-MPI data types          *
+   **********************************************************************/
+  // We are reducing at the root for a type that has no associated MPI
+  // datatype and operation, so we'll use a simple tree-based
+  // algorithm.
+  template<typename T, typename Op>
+  void
+  all_reduce_impl(const communicator& comm, const T* in_values, int n,
+                  T* out_values, Op op, mpl::false_ /*is_mpi_op*/,
+                  mpl::false_ /*is_mpi_datatype*/)
+  {
+    reduce(comm, in_values, n, out_values, op, 0);
+    broadcast(comm, out_values, n, 0);
+  }
+} // end namespace detail
+
+template<typename T, typename Op>
+inline void
+all_reduce(const communicator& comm, const T* in_values, int n, T* out_values,
+           Op op)
+{
+  detail::all_reduce_impl(comm, in_values, n, out_values, op,
+                          is_mpi_op<Op, T>(), is_mpi_datatype<T>());
+}
+
+template<typename T, typename Op>
+inline void
+all_reduce(const communicator& comm, const T& in_value, T& out_value, Op op)
+{
+  detail::all_reduce_impl(comm, &in_value, 1, &out_value, op,
+                          is_mpi_op<Op, T>(), is_mpi_datatype<T>());
+}
+
+template<typename T, typename Op>
+T all_reduce(const communicator& comm, const T& in_value, Op op)
+{
+  T result;
+  ::boost::mpi::all_reduce(comm, in_value, result, op);
+  return result;
+}
+
+} } // end namespace boost::mpi
+
+#endif // BOOST_MPI_ALL_REDUCE_HPP