Variable length decoding method and apparatus

Abstract

A variable length decoding apparatus contains a variable length code table of variable length codes which are used to decode variable length coded data and which are grouped together based on bit patterns of the variable length codes. The apparatus also includes a memory for storing the coded data in increments of N-bit data and for outputting a current N-bit data based on control signals generated in accordance with the contents of a previous N-bit data output from the memory. The apparatus also includes a controller which inputs the current N-bit data and compares the N-bit data with code state values that respectively identify the groups of the variable length codes. As a result, the controller determines the group of codes to which the current N-bit data belongs and outputs control signals based on such determination. Furthermore, the apparatus contains a combination logic portion having a plurality of input combinations, the values of which are determined based on the previous N-bit data and the current N-bit data. Moreover, the values of the input combinations respectively correspond to decoded symbols for each of the groups of variable length codes. Subsequently, a multiplexer inputs the plurality of decoded symbols and selectively outputs the symbol corresponding to the current N-bit data based on a control signal from the controller.