/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
/*
 *  (C) 2001 by Argonne National Laboratory.
 *      See COPYRIGHT in top-level directory.
 */

#include "mpi.h"
#include <stdio.h>
#include <string.h>

#define BUFLEN 512

int main(int argc, char *argv[])
{
    int myid, numprocs, next, namelen;
    char buffer[BUFLEN], processor_name[MPI_MAX_PROCESSOR_NAME];
    MPI_Status status;

    MPI_Init(&argc, &argv);
    MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
    MPI_Comm_rank(MPI_COMM_WORLD, &myid);
    MPI_Get_processor_name(processor_name, &namelen);

    fprintf(stderr, "Process %d on %s\n", myid, processor_name);
    fprintf(stderr, "Process %d of %d\n", myid, numprocs);
    strcpy(buffer, "hello there");
    if (myid == numprocs - 1)
        next = 0;
    else
        next = myid + 1;

    if (myid == 0) {
        printf("%d sending '%s' \n", myid, buffer);
        fflush(stdout);
        MPI_Send(buffer, strlen(buffer) + 1, MPI_CHAR, next, 99, MPI_COMM_WORLD);
        printf("%d receiving \n", myid);
        fflush(stdout);
        MPI_Recv(buffer, BUFLEN, MPI_CHAR, MPI_ANY_SOURCE, 99, MPI_COMM_WORLD, &status);
        printf("%d received '%s' \n", myid, buffer);
        fflush(stdout);
        /* mpdprintf(001,"%d receiving \n",myid); */
    } else {
        printf("%d receiving  \n", myid);
        fflush(stdout);
        MPI_Recv(buffer, BUFLEN, MPI_CHAR, MPI_ANY_SOURCE, 99, MPI_COMM_WORLD, &status);
        printf("%d received '%s' \n", myid, buffer);
        fflush(stdout);
        /* mpdprintf(001,"%d receiving \n",myid); */
        MPI_Send(buffer, strlen(buffer) + 1, MPI_CHAR, next, 99, MPI_COMM_WORLD);
        printf("%d sent '%s' \n", myid, buffer);
        fflush(stdout);
    }
    MPI_Barrier(MPI_COMM_WORLD);
    MPI_Finalize();
    return (0);
}
