Data compression and decompression using relative and absolute delta values

摘要

A data compressor has a delta value calculator which receives data items and determines if a related data item to a received data item is stored in a data store. If the related item is stored, the delta value calculator retrieves the related data item from the data store and calculates a delta value from the received data item and the related data item. If the related item is not stored, then the delta value is calculated from the received data item and a predetermined value. A data store controller accesses the data store in response to receipt of a data item and determines if a storage location is allocated to the data item. If there is an allocated storage location for the data item, the data item is stored in the allocated storage location; and if not then a storage location is allocated to the data item.