Hardware efficient updating technique for LZW CODEC design

This paper presents a simple yet effective dictionary updating technique suitable for the hardware implementation of LZW. The proposed windowed second chance (WSC) updating technique partitions the dictionary into several windows to minimize the complexity. The hardware overhead is 1 bit per phrase as opposed to log₂N bits for LRU updating. Our method achieves an average of 3.80 bits/char compression ratio on Corpus benchmarks, which is compatible to 3.76 of LZT with LRU updating. We implement LZW by CAM and WSC by priority encoder/decoder. Such a design is capable of compress/decompress one character per clock which makes it especially suitable for real time and on-line applications