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 affect the compression performance of the ALDC algorithm: data content, history size, and data extent. As ALDC compression is integrated into different applications, restrictions are placed upon these variables that affect the overall compression performance of the system. More complex applications require further support for higher-order data structures such as variable-length segments, error recovery, and expansion. The IBM Blue Logic ALDC and embedded 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.