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Clipping of Fields Containing Double-Byte Character Set Characters

IP.com Disclosure Number: IPCOM000039089D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Herrod, JA: AUTHOR [+3]

Abstract

To implement horizontal scrolling and overlapping of emulated portions, it is necessary to clip all forms of alphanumeric fields to fit the visible portions of the partition ensuring only that whole characters are displayed. In fields containing Double-Byte Character Set (DBCS) characters the rules relating to clipping depend on whether the field is mixed or not and on whether SOSI takes position or not. The first and last bytes of the visible strip are checked and replaced where necessary, to ensure that only whole characters and, where appropriate, SOSI pairs are displayed. The Rules For Clipping DBCS Fields The following algorithm applies to DBCS fields ensuring that when clipping on a horizontal plane takes place, only whole DBCS characters are displayed. 1.

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Clipping of Fields Containing Double-Byte Character Set Characters

To implement horizontal scrolling and overlapping of emulated portions, it is necessary to clip all forms of alphanumeric fields to fit the visible portions of the partition ensuring only that whole characters are displayed. In fields containing Double-Byte Character Set (DBCS) characters the rules relating to clipping depend on whether the field is mixed or not and on whether SOSI takes position or not. The first and last bytes of the visible strip are checked and replaced where necessary, to ensure that only whole characters and, where appropriate, SOSI pairs are displayed. The Rules For Clipping DBCS Fields The following algorithm applies to DBCS fields ensuring that when clipping on a horizontal plane takes place, only whole DBCS characters are displayed. 1.Each field is divided up into visible strip(s) depending on the parts of the field that will be clipped or overlayed. 2.The field attribute of the field is duplicated at the beginning of the visible strip. 3.The first byte of the visible strip is checked to see if it is the first or second half of a DBCS character by counting bytes from the start of the field. When the first byte of the strip is the second half of a DBCS character, then a duplicate of the field attribute replaces it. 4.An end attribute is placed at the end of the visible strip. 5.The last byte of the visible strip is checked to see if it is the first or second part of a DBCS character. If it is the first part, a duplicate end attribute is placed in its position. When SOSI takes position this means that a character position is reserved before and after a DBCS sub-field for the SO and SI symbols. In clipping the field for horizontal scrolling or overlapping of emulated partitions, this must be taken into account. The following rules apply: 1.As for DBCS fields, each field is divided up into the visible strips. 2.A duplicate of the field attribute is positioned at the start of the visible strip. 3.The first byte of the visible strip is tested in the same way as above. If it is a. the first half of a DBCS character, then the first

byte is replaced with a duplicate of the field

attribute...