An apparatus and method for processing a data signal transferred using a specific data protocol, DP, said apparatus comprising a decoding unit configured to decode stepwise the data signal according to the used data protocol, wherein said decoding unit is adapted to decode in a decoding step rising and falling signal edges as an intermediate decoding result; and a decoding result labelling unit configured to provide intermediate decoding result labels, L, for the data signal, DS, after each decoding step performed by said decoding unit and configured to map the provided decoding result labels, L, to the data signal, DS.