Abstract: Methods and devices for scanning an incoming datastream for a plurality of target patterns. The scanning system receives an incoming data stream and stores the stream as sequential symbols in a register array. Previously received symbols are shifted in the array as incoming symbols are shifted in. A trigger stage computes a hash value based on the k most recently received symbols. The trigger stage then uses the hash value to determine whether a more detailed symbol by symbol comparison is required between a group of sequential symbols stored in the array and a target pattern stored in external storage. This is done by comparing the hash value with the indices of the target patterns in the external storage. If the more detailed comparison is indicated, a full comparison stage retrieves the relevant target pattern and compares the target pattern with the sequentially stored symbols in the array.

Abstract: Methods and devices for scanning an incoming datastream for a plurality of target patterns. The scanning system receives an incoming data stream and stores the stream as sequential symbols in a register array. Previously received symbols are shifted in the array as incoming symbols are shifted in. A trigger stage computes a hash value based on the k most recently received symbols. The trigger stage then uses the hash value to determine whether a more detailed symbol by symbol comparison is required between a group of sequential symbols stored in the array and a target pattern stored in external storage. This is done by comparing the hash value with the indices of the target patterns in the external storage. If the more detailed comparison is indicated, a full comparison stage retrieves the relevant target pattern and compares the target pattern with the sequentially stored symbols in the array.