Appeal No. 1999-2714
Application No. 08/504,562
The appellant's invention relates to a file difference engine. An understanding of
the invention can be derived from a reading of exemplary claims 50, 72, 84, and 101,
which are reproduced below.
50. A combination comprising a storage device, a file stored in said
storage device, and a token table stored in said storage device, said token
table comprising first and second different hashing mathematical
representations for each of a plurality of fixed equal length character
segments of said file.
72. A combination comprising a memory, a signature and a first data file
stored in said memory, said signature indicating a difference between said
first data file and a second data file with respect to one another, said first
and second data files each having successive segments of an equal
number of characters and having a reference point at the same character
position in both of said first and second data files, said signature
comprising a plurality of offsets for said second data file, each offset
representing the distance from said reference point in said second data file
of a respective segment of said successive segments in said second data
file, which is identical to one of said segments in said first data file, the
distance from said reference point being the distance of a fixed character
position within each respective segment from said reference point.
84. A method for creating a second window segment token from a base
window segment token, said method comprising creating a base window
segment in a computer memory by reading a segment of a file in a
computer memory, said segment in said file being of the same size as said
base window segment, calculating an exclusive-or signature that is an
exclusive-or representation of the characters of said base window segment
of the file to create a base window segment token, creating said second
window segment which comprises all characters of said base window
segment except the first character of said base window segment and
comprises the next character in said file after said segment in said file
which was read to form the base window segment by reading said next
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