Abstract: A data compressor is provided which performs substitution-based data encoding. The compressor identifies repetitive data of an input file and writes meta-data representative of the repetitive data to a first buffer using a triple structure. The triple structure includes information of a length of non-repetitive data preceding repetitive data, an offset between like groups of repetitive data, and a length of the repetitive data. Non-repetitive data is written to a second buffer. The compressor concatenates the first and second buffers along with information of the length of the input file and the length of the first buffer to form a compressed file. A corresponding decompressor parses the compressed file and quickly computes the original file using a pre-allocated memory area.

Abstract: Systems and methods are provided for pre-processing original and new versions of files as part of difference file generation between the original and new file versions, for example byte-level file differencing. Software/executable changes between file versions include primary changes/logical changes, which are defined to be the source code changes, and secondary changes. The secondary changes generally result from the primary changes and are generated by the software compiler/linker utilities. The secondary changes include address changes, pointer target address changes, and changes in address offsets. The pre-processing systems and methods provided use approximation rules between file versions to remove/reduce the secondary changes and encode information relating to the removal of these changes in information of the corresponding difference file.

Abstract: An exemplary method for managing information in a mobile device comprises the steps of downloading a first set of files, determining whether a local cache has enough space to store the first set of files, storing the first set of files into the local cache if the local cache has enough space, selecting an out-dated record and removing a second set of files corresponding to the out-dated record from the local cache if the local cache does not have enough space, and repeating the determining step until the first set of files is stored into the local cache.