Cirrus Logic Inc.

Jeffrey Michael Holmes

Karl Scott Mills

Richard Charles Owen

Mark Emil Bonnelycke

A graphics controller circuit comprising a plurality of pipelines for performing a set of operations on a stream of input pixel data to generate at least a first operand and a second operand. A rasterop unit in the graphics controller circuit may receive the first operand and the second operand, and execute a raster operation using the first operand and the second operand to generate a set of display pixel data. The graphics controller circuit may further comprise a transparency unit for generating a write enable mask corresponding to the set of display pixel data. A display memory may selectively store or block the set of display pixel data according to the write enable mask. As the graphics controller generates display signals from the display data stored in display memory, a transparency operation may be performed.

Method and apparatus for executing a raster operation in a graphics

A graphics controller circuit for converting a plurality of monochrome pixel data into a corresponding set of color pixel data in RGB 888 format. The graphics controller circuit packs the converted color pixel data into a plurality of 64-bit color pixel words, with each color pixel word comprising two complete color pixel words and portion of at least one another color pixel word. By having color pixel data cross word boundaries, graphics controller of the present invention optimally stores color pixel data in color pixel words. The graphics controller circuit further includes a half-word addressable split-RAM which enables continuous availability of subsets of monochrome pixel data during each clock cycle for conversion to color data.

Method and apparatus for converting monochrome pixel data to color pixel

A method and apparatus for improving pixel data write operations to a tile-based frame buffer. The present invention includes a byte enable first-in first-out register for storing byte enable data for masking pixel data writes to a tile based frame buffer when the pixel data crosses a tile boundary. Pixel data generated by a graphics processor to the frame buffer may traverse multiple tiles. With each 64-bits of pixel data generated, a corresponding byte of byte enable data is generated as mask data for the frame buffer. The byte enable circuit of the present invention may be implemented as a circular shift register to allow the byte enable data to be shifted, rather than being 'popped' after the pixel data has been written to the frame buffer. By shifting data rather than 'popping' data, the byte enable circuit is able to retain portions of the byte enable data to enable a correct write of a pixel word which may traverse tile boundaries.

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Seattle, WA, United States of America

Jeffrey Michael Holmes