text: /*
   * Copyright (c) 2004-2007 The Trustees of Indiana University and Indiana
   *                         University Research and Technology
   *                         Corporation.  All rights reserved.
   * Copyright (c) 2004-2017 The University of Tennessee and The University
   *                         of Tennessee Research Foundation.  All rights
   *                         reserved.
   * Copyright (c) 2004-2008 High Performance Computing Center Stuttgart, 
   *                         University of Stuttgart.  All rights reserved.
   * Copyright (c) 2004-2005 The Regents of the University of California.
   *                         All rights reserved.
   * Copyright (c) 2010-2012 Oak Ridge National Labs.  All rights reserved.
   * $COPYRIGHT$
   * 
   * Additional copyrights may follow
   * 
   * $HEADER$
   */
  
  #include "ompi_config.h"
  
  #include "ompi/mpi/c/bindings.h"
  #include "ompi/runtime/params.h"
  #include "ompi/communicator/communicator.h"
  #include "ompi/errhandler/errhandler.h"
  #include "ompi/datatype/ompi_datatype.h"
  #include "ompi/op/op.h"
  #include "ompi/memchecker.h"
  
  #if OPAL_HAVE_WEAK_SYMBOLS && OMPI_PROFILING_DEFINES
  #pragma weak MPI_Exscan = PMPI_Exscan
  #endif
  
  #if OMPI_PROFILING_DEFINES
  #include "ompi/mpi/c/profile/defines.h"
  #endif
  
  static const char FUNC_NAME[] = "MPI_Exscan";
  
  
  int MPI_Exscan(void *sendbuf, void *recvbuf, int count,
                 MPI_Datatype datatype, MPI_Op op, MPI_Comm comm) 
  {
      int err;
  
      MEMCHECKER(
          memchecker_datatype(datatype);
          memchecker_call(&opal_memchecker_base_isdefined, sendbuf, count, datatype);
          memchecker_comm(comm);
      );
  
      if (MPI_PARAM_CHECK) {
          char *msg;
          err = MPI_SUCCESS;
          OMPI_ERR_INIT_FINALIZE(FUNC_NAME);
          if (ompi_comm_invalid(comm)) {
              return OMPI_ERRHANDLER_INVOKE(MPI_COMM_WORLD, MPI_ERR_COMM, 
                                            FUNC_NAME);
          }
  
          /* Unrooted operation -- same checks for intracommunicators
             and intercommunicators */
          else if (MPI_OP_NULL == op) {
              err = MPI_ERR_OP;
          } else if (!ompi_op_is_valid(op, datatype, &msg, FUNC_NAME)) {
              int ret = OMPI_ERRHANDLER_INVOKE(comm, MPI_ERR_OP, msg);
              free(msg);
              return ret;
          } else {
              OMPI_CHECK_DATATYPE_FOR_SEND(err, datatype, count);
          }
          OMPI_ERRHANDLER_CHECK(err, comm, err, FUNC_NAME);
      }
  
  #if OPAL_ENABLE_FT_MPI
      /*
       * An early check, so as to return early if we are using a broken
       * communicator. This is not absolutely necessary since we will
       * check for this, and other, error conditions during the operation.
       */
      if( OPAL_UNLIKELY(!ompi_comm_iface_coll_check(comm, &err)) ) {
          OMPI_ERRHANDLER_RETURN(err, comm, err, FUNC_NAME);
      }
  #endif
  
      /* Do we need to do anything? (MPI says that reductions have to
         have a count of at least 1, but at least IMB calls reduce with
         a count of 0 -- blah!) */
  
      if (0 == count) {
          return MPI_SUCCESS;
      }
  
      OPAL_CR_ENTER_LIBRARY();
  
      /* Invoke the coll component to perform the back-end operation */
  
      OBJ_RETAIN(op);
      err = comm->c_coll.coll_exscan(sendbuf, recvbuf, count,
                                     datatype, op, comm,
                                     comm->c_coll.coll_exscan_module);
      OBJ_RELEASE(op);
      OMPI_ERRHANDLER_RETURN(err, comm, err, FUNC_NAME);
  }
  