Design considerations for the ALDC cores

The IBM adaptive lossless data compression (ALDC) family of products uses a derivative of Lempel-Ziv encoding to compress data. Several variables affe ct the compression performance of the ALDC algorithm: data content, history size, and data extent. As ALDC compression is integrated into different ap plications, restrictions are placed upon these variables that affect the ov erall compression performance of the system. More complex applications requ ire further support for higher-order data structures such as variable-lengt h segments, error recovery, and expansion. The IBM Blue Logic ALDC and embe dded lossless data compression (ELDC) cores have been developed to work in these application environments. These cores and the issues associated with integrating data compression into a system are discussed.