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Fast Hardware Window Resource Allocation using a Dynamic Window Allocation Method

IP.com Disclosure Number: IPCOM000108402D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 46K

Publishing Venue

IBM

Related People

Anderson, G: AUTHOR [+3]

Abstract

This disclosure addresses the following performance problems: On sophisticated display adapters there are planes allocated to the management of multiple windows appearing on the screen. When four planes are built into the hardware, sixteen windows can be easily managed. The user needs to be able to bring up an unlimited number of windows. A method is needed to allocate the hardware resource dynamically so that all windows have the correct appearance. Additionally, at least one window must be render ready. In the past, more primitive methods resulted in sacrifices in performance and screen appearance under certain conditions.

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Fast Hardware Window Resource Allocation using a Dynamic Window Allocation Method

      This disclosure addresses the following performance problems:
On sophisticated display adapters there are planes allocated to the
management of multiple windows appearing on the screen.  When four
planes are built into the hardware, sixteen windows can be easily
managed.  The user needs to be able to bring up an unlimited number
of windows.  A method is needed to allocate the hardware resource
dynamically so that all windows have the correct appearance.
Additionally, at least one window must be render ready.  In the past,
more primitive methods resulted in sacrifices in performance and
screen appearance under certain conditions.

      The method described below provides a solution to these
problems.  This method maintains the window ID's in three list:  the
unused list, the unshared list, and the shared list.  New windows are
allocated window ID's from the unused list.  The newly used window ID
moves into the unshared list.  The unshared list is kept in least
recently used order, for the performance reasons described below.
All windows in the unshared list are render ready.  When no entries
remain in the unused list, the window that was least recently written
to is forced to share its window ID.  If any other windows are
already sharing a window ID and have the same pixel interpretation,
the LRU window will share with them.  Otherwise, it is forced to
share its windo...