| 摘要 |
A lossless data compression system and method compresses a set of M data words stored in a computer memory. A first table stores data representing last occurrence positions among those of the M data words already processed for all distinct word values. A second table stores for each data word an entry indicating the position, if any, of a most recent prior occurrence of another data word with the same word value. A dictionary index indicates how many distinct data word values have been encountered during processing of M data words. The M data words are processed in in said M data words previously processed, identifying a longest sequence of data words starting with said each data word referencing said second table to identify data words earlier in said M data words than said each data word that match said each data word's value, identifying a longest sequence of data words earlier in said M data words than said data word which match an equal number of data words starting with said each data word, (B1) when said longest sequence's length is greater than one data word, outputting a run length code that indicates said longest sequence's length and position, and updating said first and second tables for the equal number of data words starting said each data word, and (B2) when said longest sequence's length is equal to one data word, outputting a code that indicates the position of said identified longest sequence, and updating said first and second tables for said each data word. |
