A processing system wherein a bitmap array is first used to obtain an index. The index is used to obtain a value from an array. A predefined default value is used to improve compression and speed in cases where a single default value is often encountered. In this embodiment the size of each entry in the bitmap array is one bit. In another approach, a bitmap array having two bit entries is provided. The use of two bits allows four different entry values. Two values are used to indicate two different default values. A third value is used for a "repeat" indicator to when the last-used next-state value should be re-used. The fourth value is used to indicate indexing into a pointer table, similarly to the embodiment using single-bit entries in the bitmap array.