int tMPI_Cart_sub(tMPI_Comm comm, int *remain_dims, tMPI_Comm *newcomm)
{
int myrank;
int ndims=0;
int *dims=NULL;
int *periods=NULL;
int *oldcoords=NULL;
int i;
int ndims_notused=1;
int color_notused=0;
#ifdef TMPI_TRACE
tMPI_Trace_print("tMPI_Cart_sub(%p, %p, %p)", comm, remain_dims, newcomm);
#endif
tMPI_Comm_rank(comm, &myrank);
if ( comm->cart )
{
oldcoords=(int*)tMPI_Malloc(sizeof(int)*comm->cart->ndims);
dims=(int*)tMPI_Malloc(sizeof(int)*comm->cart->ndims);
periods=(int*)tMPI_Malloc(sizeof(int)*comm->cart->ndims);
/* get old coordinates */
tMPI_Cart_coords(comm, myrank, comm->cart->ndims, oldcoords);
for(i=0;i<comm->cart->ndims;i++)
{
if (remain_dims[i])
{
/* for the remaining dimensions, copy dimensionality data */
dims[ndims]=comm->cart->dims[i];
periods[ndims]=comm->cart->periods[i];
ndims++;
}
else
{
/* base color on not used coordinates. We keep a
ndims_notused index multiplier.*/
color_notused += oldcoords[i]*ndims_notused;
ndims_notused *= comm->cart->dims[i];
}
}
}
/* key=myrank, because we want the order to remain the same */
tMPI_Comm_split(comm, color_notused, myrank, newcomm);
tMPI_Cart_init(newcomm, ndims, dims, periods);
if (oldcoords)
free(oldcoords);
if (dims)
free(dims);
if (periods)
free(periods);
return TMPI_SUCCESS;
}
int tMPI_Cart_create(tMPI_Comm comm_old, int ndims, int *dims, int *periods,
int reorder, tMPI_Comm *comm_cart)
{
int myrank = tMPI_Comm_seek_rank(comm_old, tMPI_Get_current());
int key = myrank;
int color = 0;
int Ntot = 1;
int i;
#ifdef TMPI_TRACE
tMPI_Trace_print("tMPI_Cart_create(%p, %d, %p, %p, %d, %p)", comm_old,
ndims, dims, periods, reorder, comm_cart);
#endif
if (!comm_old)
{
return tMPI_Error(comm_old, TMPI_ERR_COMM);
}
/* calculate the total number of procs in cartesian comm */
for (i = 0; i < ndims; i++)
{
Ntot *= dims[i];
}
/* refuse to create if there's not enough procs */
if (comm_old->grp.N < Ntot)
{
*comm_cart = TMPI_COMM_NULL;
#if 1
return tMPI_Error(comm_old, TMPI_ERR_CART_CREATE_NPROCS);
#endif
}
if (key >= Ntot)
{
key = TMPI_UNDEFINED;
}
if (reorder)
{
tMPI_Cart_map(comm_old, ndims, dims, periods, &key);
}
if (key == TMPI_UNDEFINED)
{
color = TMPI_UNDEFINED;
}
tMPI_Comm_split(comm_old, color, key, comm_cart);
tMPI_Cart_init(comm_cart, ndims, dims, periods);
return TMPI_SUCCESS;
}
