In a decoder for decoding a low density parity check (LDPC) code suitable for decoding multi-rated LDPC codes, a method is provided. The method comprises the steps of: providing a memory for the decoding with the memory dependent on a parity check matrix H with maximum number of “1”s; using a number of column updating units, updating columns parallely and simultaneously producing messages; and using a number of row updating units, updating rows parallely and simultaneously producing messages. Whereby an improved architecture in a logic and the memory is provided such that an improved throughput, power consumption, and memory area is achieved.