Patent ID: 8321439

Claim:
A first one or more computer readable storage media having computer executable instructions that, when executed on at least one processor, configure the at least one processor to perform a method of detecting if a target file name exists on a second one or more computer readable storage media, the method comprising: (A) determining a name hash from the target name; (B) determining if the name hash corresponds to a directory entry set name hash value, the directory entry set name hash value corresponding to one of a plurality of directory entry sets, each of the plurality of directory entry sets stored on the second one or more computer readable storage media; (C) determining if the target name matches a directory entry set name corresponding to the one of the plurality of directory entry sets after step (B) determines the name hash corresponds to the directory entry set name hash value; and (D) indicating that the target name exists after step (C) determines the target name matches the directory entry set name, the step (A) comprising: determining the target name corresponds to one of a predetermined set of names, the predetermined set of names having a common portion; initializing a temporary value to a predetermined start value, the predetermined start value corresponding to a pre-computed partial hash value corresponding to the common portion; for each character of the target name other than the common portion: rotating the temporary value right by at least one bit; converting the character from a first value to a second value based upon a conversion table; and adding the second value to the temporary value; and using the temporary value as the name hash.