Browse Prior Art Database

Compare Until Substring Equal

IP.com Disclosure Number: IPCOM000120706D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 49K

Publishing Venue

IBM

Related People

Linquist, B: AUTHOR [+6]

Abstract

This is a generalized mechanism to compare two strings and determine the position where equal substrings of a specified length occur. If the substring length is specified as one, this mechanism determines the position where both strings contain the same byte. (Image Omitted)

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 77% of the total text.

Compare Until Substring Equal

      This is a generalized mechanism to compare two strings and
determine the position where equal substrings of a specified length
occur.  If the substring length is specified as one, this mechanism
determines the position where both strings contain the same byte.

                            (Image Omitted)

      This mechanism is proposed in the form of a COMPARE UNTIL
SUBSTRING EQUAL (CUSE) instruction.  The figure illustrates the use
of this mechanism to compare two strings, record N and record N+1, to
identify unequal section shown with /////// (all other portions of
the records are assumed equal).

      The well-known COMPARE LOGICAL LONG (CLCL) instruction is used
to identify the byte location 'a' where the modified (unequal)
portion starts.  From position 'a', this new instruction, CUSE is
used to identify position 'b', after which a predetermined length of
the strings are equal.  This determines the changed portion from byte
location 'a' to 'b'.

      The changed portion from 'a' to 'b' may contain one or more
substrings that are the same in both record N and record N+1, but
each of which is shorter than the predetermined length.  CUSE allows
these too short equal substrings to be ignored; that is, treated as
part of long (from 'a' to 'b') unequal substrings.  In applications
where only the changed portion of a record is stored, this ability of
CUSE to find "significantly equal" subs...