Primefaces: set page on datatable

public void setPageDataTable() {
final DataTable d = (DataTable) FacesContext.getCurrentInstance().getViewRoot()
.findComponent("form:templateTable");
int first = 1;
if (d.getRowCount() % ROWS_DATATABLE == 0) {
first = (d.getRowCount() - ROWS_DATATABLE);
}
else
{
first = (d.getRowCount()/ROWS_DATATABLE)*ROWS_DATATABLE;
}
d.setFirst(first);
}