#include <stdio.h>
#include <mpi.h>
/* for sleep() */ 
#include <unistd.h> 

#define Uflag -99235
void printival(char *s, int ival)
{ 
  printf(s);
  if (ival==Uflag) 
  { printf("U");
  } else if (ival==MPI_PROC_NULL) {
    printf("MPI_PROC_NULL");
  } else if (ival==MPI_UNDEFINED) {
    printf("MPI_UNDEFINED");
  } else {
    printf("%1d",ival);
  }
} 
 
void report_topo(int myrank, char *name, MPI_Comm cart)
{ 
   int size, rank, status;
   MPI_Comm_size(cart, &size);
   MPI_Comm_rank(cart, &rank);
   MPI_Topo_test(cart, &status); 
   printf("[%02d] %s: size=%1d rank=%1d %s",
      myrank, name, size, rank,
      (status==MPI_CART ? "CART" : "NOT-CART") );
   if (status==MPI_CART)
   { int ndims;
     MPI_Cartdim_get(cart,&ndims); 
     printf("  ndims=%1d", ndims); 
     if (ndims >= 0) 
     { int dims, periods, coords;
       dims=Uflag; periods=Uflag; coords=Uflag; 
       MPI_Cart_get(cart,1,&dims,&periods,&coords);
       printival("  dims=",dims);  
       printival("  periods=",periods);  
       printival("  coords=",coords);  
     } 
   } 
   printf("\n"); fflush(stdout);
}
 
int main(int argc, char *argv[])
{

   int myrank, size, periods, reorder, remain_dims, status, coords, rank, src, dest, dims; 
   MPI_Comm cart1dim, sub0dim, subsub0dim, cart0dim;  

   MPI_Init(&argc, &argv);
 
   MPI_Comm_size(MPI_COMM_WORLD, &size);
   MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
   for (periods=0; periods<=1; periods++)
   { 
     MPI_Barrier(MPI_COMM_WORLD); 
     sleep(1); 
     if (myrank==0) printf("\nndim=0 generated via MPI_Cart_sub(remain_dims=0) -- periods=%1d\n\n",periods);
     fflush(stdout);
     sleep(1); 
     MPI_Barrier(MPI_COMM_WORLD); 
     reorder=0;
     MPI_Cart_create(MPI_COMM_WORLD,1,&size,&periods,reorder,&cart1dim); 
     report_topo(myrank, "cart1dim", cart1dim); 
     remain_dims=0; 
     MPI_Cart_sub(cart1dim,&remain_dims,&sub0dim);
     report_topo(myrank, "sub0dim", sub0dim); 
     MPI_Topo_test(sub0dim, &status); 
     if (status==MPI_CART)
     { 
       coords=0;  rank=Uflag; 
       MPI_Cart_rank(sub0dim, &coords, &rank); 
       printf("[%02d] MPI_Cart_rank(sub0dim,coords=0,OUT rank) -->",myrank); 
       printival("  rank=",rank); 
       printf("\n"); fflush(stdout);
 
       rank=0;  coords=Uflag; 
       MPI_Cart_coords(sub0dim, rank, 1, &coords); 
       printf("[%02d] MPI_Cart_coords(sub0dim,rank=0,maxdims=1,OUT coords) -->",myrank); 
       printival("  coords=",coords); 
       printf("\n"); fflush(stdout);
/* 
       src=Uflag; dest=Uflag; 
       MPI_Cart_shift(sub0dim, 0, 1, &src, &dest); 
       printf("[%02d] MPI_Cart_shift(sub0dim,dir=0,disp=1,OUT src, OUT dest) -->",myrank); 
       printival("  src=",src); 
       printival("  dest=",dest); 
       printf("\n"); fflush(stdout);
*/ 
       MPI_Cart_sub(sub0dim,&remain_dims,&subsub0dim);
       report_topo(myrank, "subsub0dim", subsub0dim); 
     } 
   } 
 
   for (periods=0; periods<=1; periods++)
   { 
     MPI_Barrier(MPI_COMM_WORLD); 
     sleep(1); 
     if (myrank==0) printf("\nndim=0 generated directly with MPI_Cart_create(ndims=0) -- periods=%1d\n\n",periods);
     fflush(stdout);
     sleep(1); 
     MPI_Barrier(MPI_COMM_WORLD); 
     reorder=0;
     dims=1; 
     MPI_Cart_create(MPI_COMM_SELF,0,&dims,&periods,reorder,&cart0dim); 
     report_topo(myrank, "cart0dim", cart0dim); 
     MPI_Topo_test(cart0dim, &status); 
     if (status==MPI_CART)
     { 
       coords=0;  rank=Uflag; 
       MPI_Cart_rank(cart0dim, &coords, &rank); 
       printf("[%02d] MPI_Cart_rank(cart0dim,coords=0,OUT rank) -->",myrank); 
       printival("  rank=",rank); 
       printf("\n"); fflush(stdout);
 
       rank=0;  coords=Uflag; 
       MPI_Cart_coords(cart0dim, rank, 1, &coords); 
       printf("[%02d] MPI_Cart_coords(cart0dim,rank=0,maxdims=1,OUT coords) -->",myrank); 
       printival("  coords=",coords); 
       printf("\n"); fflush(stdout);
 
/* 
       src=Uflag; dest=Uflag; 
       MPI_Cart_shift(cart0dim, 0, 1, &src, &dest); 
       printf("[%02d] MPI_Cart_shift(cart0dim,dir=0,disp=1,OUT src, OUT dest) -->",myrank); 
       printival("  src=",src); 
       printival("  dest=",dest); 
       printf("\n"); fflush(stdout);
*/ 
       MPI_Cart_sub(cart0dim,&remain_dims,&subsub0dim);
       report_topo(myrank, "subsub0dim", subsub0dim); 
     } 
   } 

   MPI_Finalize();
}