Variable length code detection in a signal processing system

Abstract

A group of incoming data stream bits having packed variable length code ('VLC') words is applied to an entropy code bit length searching module. The group of bits is replicated within a plurality of matching modules selectively distributed among entropy code bit length searching logic units. Each unit of entropy code bit length searching logic supports a VLC word table as characterized by, for example, standard compression formats such as MPEG-1, MPEG-2, H.261, and H.263. The matching modules are divided into groups within the entropy code bit length searching logic units. A group of matching modules is allocated to each VLC bit length represented in the associated VLC word supported table. A number of matching modules are allocated to each bit length equal to a minimum number of patterns unique to VLC words of a particular bit length. The matching modules compare an incoming data group to respective patterns. A detected match is indicated by an appropriately set group output signal. Each entropy code bit length searching logic unit includes a bit length encoder that receives the group output signals. The set group output signal indicates the bit length of a current VLC, and the bit length encoder encodes this information into a bit length code output signal. The bit length code signal is utilized by a shifter to parse a corresponding bit length of current data. The parsed current data may be directly applied to an address generator which generates an output signal for a decoding look up table.