Raster engine with hardware cursor
First Claim
Patent Images
1. A video controller for interfacing a frame buffer to a dual scan display having adjacent first and second display portions with a display boundary therebetween, the video controller comprising:
- a raster engine that receives video data from the frame buffer, formats the video data, and renders the formatted data to the dual scan display line by line; and
a hardware cursor that selectively overlays a cursor image across the display boundary onto the first and second display portions, the hardware cursor comprises a cursor line buffer that overlays a first portion of the cursor image into a first data path of the raster engine according to a comparison of a first vertical counter value with a first cursor start address and a comparison of a horizontal counter value in the raster engine with a cursor column start value and a cursor image width value in the hardware cursor.
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Abstract
An improved raster engine adapted to render video data from a frame buffer to one of a plurality of disparate displays is disclosed which comprises an integral bounded video signature analyzer, a hardware cursor apparatus supporting dual scanned displays, programmatic support for multiple disparate display types, multi-mode programmable hardware blinking, programmable multiple color depth digital display interface, and programmable matrix controlled grayscale generation.
33 Citations
21 Claims
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1. A video controller for interfacing a frame buffer to a dual scan display having adjacent first and second display portions with a display boundary therebetween, the video controller comprising:
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a raster engine that receives video data from the frame buffer, formats the video data, and renders the formatted data to the dual scan display line by line; and a hardware cursor that selectively overlays a cursor image across the display boundary onto the first and second display portions, the hardware cursor comprises a cursor line buffer that overlays a first portion of the cursor image into a first data path of the raster engine according to a comparison of a first vertical counter value with a first cursor start address and a comparison of a horizontal counter value in the raster engine with a cursor column start value and a cursor image width value in the hardware cursor. - View Dependent Claims (2, 3, 4)
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5. A method of overlaying a cursor image onto a dual scan display in a video controller for interfacing a frame buffer to a dual scan display having adjacent first and second display portions with a display boundary therebetween, the method comprising:
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rendering video data from the frame buffer to the dual scan display using a raster engine; selectively overlaying a cursor image across the display boundary onto the first and second display portions according to a cursor position using a hardware cursor, wherein overlaying the cursor image across the display boundary comprises determining first and second portions of the cursor image when the cursor image crosses the display boundary, comprising; comparing a first vertical counter value in the raster engine with a first cursor start address and a first cursor portion height value in the hardware cursor, and comparing a horizontal counter value in the raster engine with a cursor column start value and a cursor image width value in the hardware cursor. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A hardware cursor for overlaying a cursor image onto a dual scan display having adjacent first and second display portions with a display boundary therebetween, comprising:
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means for receiving video data and displaying the video data on the dual scan display; means for con concurrently overlaying a cursor image generated via the hardware cursor onto the first and second display portions according to a cursor position; and means for determining a first portion of the cursor image when the cursor image crosses the display boundary, comprising; means for comparing a first vertical counter value in the raster engine with a first cursor start address and a first cursor portion height value in the hardware cursor; and means for comparing a horizontal counter value in the raster engine with a cursor column start value and a cursor image width value in the hardware cursor. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification