Browse Prior Art Database

Item-Mapping Subsystem

IP.com Disclosure Number: IPCOM000105194D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 130K

Publishing Venue

IBM

Related People

Anderson, K: AUTHOR [+3]

Abstract

Disclosed is a method of mapping one item of a given type to one or more items of another type. The mapped items must follow a precedence order that allows the user to determine the best match. The mapping must allow for bi-directional mapping. The user must be able to dynamically add, reorder, and delete table entries. The mapping functions must return the mapped items as quickly as possible.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 36% of the total text.

Item-Mapping Subsystem

      Disclosed is a method of mapping one item of a given type to
one or more items of another type.  The mapped items must follow a
precedence order that allows the user to determine the best match.
The mapping must allow for bi-directional mapping.  The user must be
able to dynamically add, reorder, and delete table entries.  The
mapping functions must return the mapped items as quickly as
possible.

The item mapping subsystem consist of:

1.  A method to create a base, bi-directional mapping table which
    allows for one to one and one to many mappings.  Precedence order
    is maintained for one to many mappings.
2.  An application programming interface (API) to store and access
    map entries into the mapping tables in memory.
3.  A method to add bi-directional extensions to the base mapping
    table including a way to add item entries, delete item entries,
    and reorder item entries.  The extensions are embodied in an
    extension mapping table.
4.  A novel hashing algorithm that minimizes key collisions in the
    mapping table.
5.  Methods for storing the base mapping table and any extensions in
    a file.  The method ensures file integrity when the file is read
    an minimizes access time to the file when writing and reading.

      The need for a one to one and one to many bi-directional
mapping table is illustrated in the following example.  A particular
vendor's font format usually employs a unique character naming
scheme.  When converting from one font format to another it becomes
necessary then to "map" character names across the two font formats.
Unfortunately, this task is not always a simple one-to-one mapping
due to character set incompatibilities across font formats.  For
example, consider the one-to-many character name mappings in Fig. 1
which may need to be established with distinct precedence rules,
between font formats F1 and F2.

The mapping table in Fig. 1 is interpreted as:

          Char name (F1)                Char name (F2)
          -------------                 -------------
          space           ---->      SP010000
          space           ---->      SP300000

          spacerequired  <----       SP300000
          space          <----       SP300000

Fig. 1

o   The item name space primarily maps to item SP010000.  If for some
    reason the primary mapping is insufficient, then use the
    secondary mapping SP300000.
o   When mapping in the other direction, SP300000 primarily maps to
    spacerequired.  In this direction, space must be a secondary
    mapping.

The mapping subsystem disclosed in this invention solves this
problem.

      The base mapping table originates as a human readable file
shown in Fig. 2.  Each line of the text file is made up of four parts
or field...