| 摘要 |
<p>An output sequence of data elements 203 representing a sequence of input data elements 201 in compressed format, each output data element comprising a backward reference 207 to matched strings, is further processed by an extended matcher to improve the compression ratio. The extended matcher identifies a backward reference in a selected output data element, selects the string to which it refers and then combines it with strings of one or more subsequent output data elements to form one or more combined strings. The extended matcher then looks for a sequence in the stored input data elements matching at least part of the one or more the combined strings, and selects a combined string having the longest matching sequence. The backward reference of the output data element is then redefined 217 by the extended matcher to indicate the new longest matching sequence. The compression system may have a multi-stage pipeline structure. The compression may be LZ77.</p> |
