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 systems for determining which groups of instructions are to be executed when a specific symbol patterns has been detected. A prefetch block receives an identification of the symbol pattern detected. The prefetch block then retrieves the groups of instructions which relate to that particular symbol pattern. These are passed to an execution block that retrieves state information for each user defined rule from which the groups of instructions originate. The execution block then checks, for each group of instructions, the state information. If the state information indicates that a particular group of instructions can be executed, the execution block executes that group.

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.