//---------------------------------------------------------------------
//---------------------------------------------------------------------
#include "header.h"

void compute_buffer_size(int dim) {

//---------------------------------------------------------------------
//---------------------------------------------------------------------

      int  c, face_size;

      if (ncells == 1) return;

//---------------------------------------------------------------------
//     compute the actual sizes of the buffers; note that there is 
//     always one cell face that doesn't need buffer space, because it 
//     is at the boundary of the grid
//---------------------------------------------------------------------
      west_size = 0;
      east_size = 0;

      for (c = 1; c <= ncells; c++) {
         face_size = cell_size(2,c) * cell_size(3,c) * dim * 2;
         if (cell_coord(1,c)!=1) west_size = west_size + face_size;
         if (cell_coord(1,c)!=ncells) east_size = east_size + 
              face_size ;
      }

      north_size = 0;
      south_size = 0;
      for (c = 1; c <= ncells; c++) {
         face_size = cell_size(1,c)*cell_size(3,c) * dim * 2;
         if (cell_coord(2,c)!=1) south_size = south_size + face_size;
         if (cell_coord(2,c)!=ncells) north_size = north_size + 
              face_size ;
      }

      top_size = 0;
      bottom_size = 0;
      for (c = 1; c <= ncells; c++) {
         face_size = cell_size(1,c) * cell_size(2,c) * dim * 2;
         if (cell_coord(3,c)!=1) bottom_size = bottom_size + 
              face_size;
         if (cell_coord(3,c)!=ncells) top_size = top_size +
              face_size     ;
      }

      start_send_west   = 1;
      start_send_east   = start_send_west   + west_size;
      start_send_south  = start_send_east   + east_size;
      start_send_north  = start_send_south  + south_size;
      start_send_bottom = start_send_north  + north_size;
      start_send_top    = start_send_bottom + bottom_size;
      start_recv_west   = 1;
      start_recv_east   = start_recv_west   + west_size;
      start_recv_south  = start_recv_east   + east_size;
      start_recv_north  = start_recv_south  + south_size;
      start_recv_bottom = start_recv_north  + north_size;
      start_recv_top    = start_recv_bottom + bottom_size;

      return;
}