Sliding window data compression method and apparatus
US5798718A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 12, 1997 |
| Grant date | Aug 25, 1998 |
| Priority date | — |
| Expiry date | May 12, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M7/46
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method for compressing a data stream, where a first portion of the data stream is read into a window having a history buffer and look-ahead buffer. An index, based on a fourth portion of the data stream in the look-ahead buffer is used to select an entry in a pointer array. An initial entry in a record array is selected based on the pointer array entry. A third portion of the data stream is selected. The third portion is compared to a second portion in the look-ahead buffer. If the third portion does not match the second portion, then a subsequent entry in the record array is selected, and the is designated as the initial entry. These steps are repeated until either the third portion matches the second portion, or no more entries are left in the record array. When there are no more entries left in the record array, the second portion is written to the output file, and the first portion read into the window is incremented by a predetermined amount. When the third portion matches the second portion, the history buffer address of the third portion and a length value, representing how many bytes of the third portion and the second portion matched, are output to the output file, and t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.