Improving the speed of LZ77 compression by hashing and suffix sorting

Two new algorithms for improving the speed of LZ77 compression are proposed . One is based on a new hashing algorithm named two-level hashing that enab les fast longest match searching from a sliding dictionary and the other us es suffix sorting. The former is suitable for small dictionaries and it sig nificantly improves the speed gzip, which uses a naive hashing algorithm. T he latter is suitable for large dictionaries which improve compression rati o for large files. We also experiment on the compression ratio and the spee d of block sorting compression, which uses suffix sorting in its compressio n algorithm. The results show that the LZ77 using the two-level hash is sui table for small dictionaries, the LZ77 using suffix sorting is good for lar ge dictionaries when fast decompression speed and efficient use of memory a re necessary, and block sorting is good for large dictionaries.