Browse Prior Art Database

Object Identifier Remapping

IP.com Disclosure Number: IPCOM000121573D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 3 page(s) / 109K

Publishing Venue

IBM

Related People

Thirkeld, DR: AUTHOR

Abstract

An algorithm is disclosed that improves GSLOAD symbol set remapping in the Graphical Data Display Manager (GDDM) Version 2. It can be extended to cover any object type referenced, for efficiency within the picture file, by a local identifier.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Object Identifier Remapping

      An algorithm is disclosed that improves GSLOAD symbol set
remapping in the Graphical Data Display Manager (GDDM) Version 2.  It
can be extended to cover any object type referenced, for efficiency
within the picture file, by a local identifier.

      When merging picture files, such as metafiles, containing
objects such as symbol sets, a problem arises if one picture file,
P1, contains a symbol set A with a local identifier 'x' and the other
picture file, P2, contains a symbol set B with the same local
identifier of 'x'. Elements in both pictures which reference the
identifier 'x' will, because of the ambiguity of the identifier, not
necessarily reference the correct symbol set.  There is also some
degree of inefficiency if a symbol set A has a local identifier 'x'
in P1 and the same symbol set has a different local identifier 'y' in
P2.  The resultant composite picture file will have allocated two
distinct local identifiers to the same symbol set.

      The first problem is undesirable in the merging of two picture
files as the composite picture will not necessarily reflect the sum
of the individual parts.  The second problem is concerned with
efficiency.

      The characteristics of a symbol set are that the end user or
application programmer allocates a local identifier to a symbol set
'A' type 't'; and when drawing orders within the picture file to
utilize the symbol set 'A', they reference it by its numeric
identifier.  There is a finite range of numeric identifiers that can
be used to reference symbol sets and hence a limit to the number of
symbol sets that can be referenced within a picture file at any one
time.
The Algorithm

      When merging a picture file P2 with a 'loaded' picture file P1,
the following process should occur before the merging takes place:- A
bit table (T1) is initialized with all bits set to zero.  Each bit
position in T1 corresponds to a valid local identifier (e.g.,
position 65 in T1 represents local identifier 65).  The size of T1 is
dependant upon the range of valid local identifiers.  The contents of
P1 are scanned for any symbol set references and their associated
local identifiers.  For each local identifier found, the bit
corresponding to that local identifier within T1 is set to '1' to
indicate that the identifier is in use.  After scanning P1, T1
represents a bit map of all the local identifiers that have been
allocated to symbol sets used within P1.  Now initialize the symbol
set identifier translation table T2 to 'no translation' (i.e., each
position within the translation table is set to e'null'). T2 is
identical to T1 except that each position within T2 can contain a
local identifier as opposed to just one bit. Each time the picture
file P2 references a symbol set 'A' with type 't' and local
identifier 'x' the following subroutine, MAPSS, is called.
MAPSS Subroutine
 Clear flag F1
 Scan the list of entries of symbol sets which alr...