A macrocell including an adder block with a plurality of bit-slice adders, a bypass path and a control unit adapted to receive a carry of a first neighboring macrocell, and to output a carry by generation within the adder block or by passage of the carry of the first neighboring macrocell through the bypass path to a second neighboring macrocell. The control unit is adapted to signal a validity of the carry output of the macrocell depending on a logical combination of states of the two carry output lines. The control unit is further adapted, depending on a validity signal of the first neighboring macrocell indicating a validity of the carry, to prevent forwarding the carry.