Implementation Of LZ77 And LZW Hybird Compression Algorithm Based On FPGA

Internet technology of digital information age produced vast amounts of data. Complex systems, frequent exchange of data and real-time data processing have the higher demands on storage and network transmission of information. Lossless data compression technology could improve the data transmission, storage and processing efficiency by reducing the data redundancy to save the storage space without losing valid information. LZ77 and LZW algorithms, as the typical representations of dictionary compression algorithms, have good performance, moderate complexity, ease of hardware design and other characteristics, however, the software implementation could not be applied in real-time compression due to its low processing speed. Hardware implementation had drew more attention gradually because of the parallel computing and pipeline structure advantages.Based on LZ77 and LZW compression algorithms principles, the dual Hash function, parallel match processing, more effective LZ77 data storage format, high-performance data adaptor and parallel Hash search were involved to design the LZ77 and LZW compression circuits by analyzing the various key factors that influencing the LZ77 and LZW compression performance. The hybird compression circuit was designed, based on the features of algorithms, with the integration of LZ77 and LZW algorithms. By setting configurations to adjust the balance between compression rate and compression speed or implement the hybird or independent compression.The hybird compression circuit was verified and tested by using Xilinx Virtex-6 ML605 Field Programmable Gate Array (FPGA) and Calgary Corpus. The test data shows that, the LZ77 and LZW compression circuits could achieve good compression rate (42.85%) or high compression speed (171.2Mbps) with different configurations. Compared with software implementation, the compression speed of hardware circuit is improved significantly. The hybird compression circuit could optimize the compression rate (39.66%) while achieve the high compression speed. And different operation modes could satisfy the real-time compression requests of network communication and data storage.