The invention provides method and system for extracting rule specific data from a computer word. The method comprises: calculating at least one decimal value based on a rule representation associated with a rule, the rule representation is a byte array, value of each bit of the byte array representing whether a corresponding bit position in the computer word has a data component; identifying at least one result byte array based on the calculated decimal value from a preset look-up table, which includes a plurality of mappings, each between a result byte array and a decimal value, the result byte array indicating a set of reference bit positions for determining a set of bit positions in the computer word in which data components related to the rule are stored, and a last byte of the result byte array representing a bit count value associated with the set of reference bit positions.