private final long EMPTY_BOARD = 0x0000000000000000;

public void foo() {
        long board = 0x0000000000000000; //empty board
        for(int x = 0; x < grid.length(); x++) { //the web applications sorts the grid by columns
            JSONArray column = grid.getJSONArray(x);
            for(int y = 0; y < column.length(); y++) {
                Object raw = column.opt(y);
                int pow = 0;
                if(raw != null && raw instanceof JSONObject) {
                    JSONObject cell = (JSONObject) raw;
                    pow = lb(cell.getInt("value"));

                    if(pow > 15) {
                        //TODO: Handle overflow
                        return "overflow";
                    }
                }

                int value = Integer.valueOf(Integer.toHexString(pow), 16);
                int position = x * 4 + y;

                board = board & ((EMPTY_BOARD & value) >> position);

            }

}