#include <stdio.h>
#include <cstring>
#include <iostream>

#include <mpi.h>

using namespace std;

/******************************/
/* function to create my struct */
void
// JMS: Need to pass references to the variables, not the pointers
Build_derived_type(double &a, double &b, int &n,
		   MPI_Datatype * mesg_mpi_t_ptr)
{				       //start Build_derived_type

  int block_lengths[3];
  MPI_Aint displacements[3];
  MPI_Datatype typelist[3];
  MPI_Aint start_address;
  MPI_Aint address;
  block_lengths[0] = block_lengths[1] = 10;
  block_lengths[2] = 1;
  typelist[0] = MPI_DOUBLE;
  typelist[1] = MPI_DOUBLE;
  typelist[2] = MPI_INT;
  displacements[0] = 0;
  // JMS: 
  MPI_Address(&a, &start_address);
  MPI_Address(&b, &address);
  displacements[1] = address - start_address;
  MPI_Address(&n, &address);
  displacements[2] = address - start_address;

  MPI_Type_struct(3, block_lengths, displacements, typelist,
		  mesg_mpi_t_ptr);
  MPI_Type_commit(mesg_mpi_t_ptr);


}				       //end Build_derived_type

/********************************/
int
main(int argc, char *argv[])
{				       //start main
  int numprocs, myrank, namelen, i, n;
// double *A,* B;
  MPI_Datatype mytype;
  MPI_Request Reqs;
  char processor_name[MPI_MAX_PROCESSOR_NAME];
  char greeting[MPI_MAX_PROCESSOR_NAME + 80];
  MPI_Status status;
  MPI_Init(&argc, &argv);
  MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
  MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
  MPI_Get_processor_name(processor_name, &namelen);
/* pointer to an array */
  double *A = new double[10];
  double *B = new double[10];
  // JMS: Pass the variables themselves, not pointers to them -- so
  // then the reference is taken.
  Build_derived_type(A[0], B[0], myrank, &mytype);
  if (myrank == 0) {
    for (i = 0; i < 10; i++) {
      A[i] = (double) i;
      B[i] = (double) i + 10;
    }
    for (i = 0; i < 10; i++)
      cout << "A [ " << i << " ] = " << A[i] << " **** B [ "
	<< i << " ]= " << B[i] << endl;
    // JMS: The count should be "1"
    MPI_Isend(A, 1, mytype, 1, 1, MPI_COMM_WORLD, &Reqs);
    MPI_Wait(&Reqs, &status);
  } else if (myrank == 1) {
    // JMS: The count should be "1"
    MPI_Irecv(A, 1, mytype, 0, 1, MPI_COMM_WORLD, &Reqs);
    MPI_Wait(&Reqs, &status);
    for (i = 0; i < 10; i++)
      cout << "A [ " << i << " ] = " << A[i] << " **** B [ "
	<< i << " ]= " << B[i] << endl;
  }

  MPI_Finalize();
  return (0);
}				       //end main