#include <stdio.h>
#include <omp.h>
#include <mpi.h>
#include <string.h>  /* memset */


#define N 10000
int main(int argc, char **argv) {
  int np, me, buf[2][N], provided;

  /* init some stuff */
  MPI_Init_thread(&argc, &argv, MPI_THREAD_MULTIPLE, &provided);
  MPI_Comm_size(MPI_COMM_WORLD,&np);
  MPI_Comm_rank(MPI_COMM_WORLD,&me);
  if ( provided < MPI_THREAD_MULTIPLE ) MPI_Abort(MPI_COMM_WORLD,-1);

  /* initialize the buffers */
  memset(buf[0], 0, N * sizeof(int));
  memset(buf[1], 0, N * sizeof(int));

  /* test */
  #pragma omp parallel num_threads(2)
  {
    int id = omp_get_thread_num();
    MPI_Status st;
    printf("%d %d in parallel region\n", me, id); fflush(stdout);

    /* pingpong */
    if ( me == 0 ) {
      MPI_Send(buf[id],N,MPI_INT,1,7+id,MPI_COMM_WORLD    ); printf("%d %d sent\n",me,id); fflush(stdout);
      MPI_Recv(buf[id],N,MPI_INT,1,7+id,MPI_COMM_WORLD,&st); printf("%d %d recd\n",me,id); fflush(stdout);
    } else {
      MPI_Recv(buf[id],N,MPI_INT,0,7+id,MPI_COMM_WORLD,&st); printf("%d %d recd\n",me,id); fflush(stdout);
      MPI_Send(buf[id],N,MPI_INT,0,7+id,MPI_COMM_WORLD    ); printf("%d %d sent\n",me,id); fflush(stdout);
    }
  }

  MPI_Finalize();

  return 0;
}