Low cost searching method and apparatus for asynchronous transfer mode systems

摘要

A method and an apparatus for searching a bit field whose significant bits comprise two contiguous bit fields such as the VPI/VCI bit fields of an ATM cell header. The invention uses a hash key based on CRC-n calculated on the bit field to be searched. One m bit field part of the significant bits of the bit field to be searched can be concatenated with the CRC-n to form a double hash key. It appears that, L being the total of the two contiguous bit field lengths, if L=m=n+p, p being greater or equal to 4, the scattering of data to be searched is perfect. The method comprised a first step of pointing to a first address with the hash (or double hash) key and reading a maximum of 2p addresses before reaching the addresses containing the bit field to be searched.