read_n_cells
return read_n_cells(n_mem_size_cells, usm);
base = read_n_cells(n_mem_addr_cells, usm);
size = read_n_cells(n_mem_size_cells, usm);
start = read_n_cells(n_mem_addr_cells, &memcell_buf);
size = read_n_cells(n_mem_size_cells, &memcell_buf);