20120059804 | Data compression and decompression using relative and absolute delta values - A data compressor is disclosed for receiving a data stream comprising a plurality of data items and for outputting a compressed data stream, said data compressor comprising: a data input for receiving said data stream; a delta value calculator for generating a compressed delta value, said delta value calculator being configured to receive said plurality of data items from said data input and being configured for at least some of said received data items to access said data store to determine if a related data item to said received data item is stored in said data store and: in response to said related data item being stored, to retrieve said related data item from said data store and to calculate a delta value from said received data item and said related data item and to output said delta value; and in response to said related data item not being stored in said data store to calculate a delta value from said received data item and a predetermined value and to output said delta value; a data store for storing said plurality of data items received at said data input; said data compressor further comprising: a data store controller for controlling the storage of said plurality of data items in said data store, said data store controller being configured to access said data store in response to receipt of a data item at said data input and to determine if a storage location is allocated to said data item and: if so to store said data item in said allocated storage location; and if not to allocate a storage location to said data item and to evict and discard any data stored in said allocated storage location and to store said data item in said allocated storage location. A data decompressor for decompressing the compressed data stream is also disclosed. | 03-08-2012 |