Hewlett-packard Company

Bradley W Cain

Randall Don Briggs

Russ William Herrell

Theodore G Rossin

Eric C Nelson

A device for distributing a serial stream of commands and associated data to a parallel array of processing units so that the data processed by the parallel processing units can be recombined in the original order in which the serial stream was received. The command distributor of the invention hands out commands to the parallel processing units using a true 'first come, first serve' algorithm using fast bus arbitration hardware. Each parallel processing unit requests data to be input when all of its data has been processed, and bus arbitration is used to prevent conflict when a plurality of requests are received. The ID of the processor to which a command is assigned is used in recombining the processed data into a serial data stream having the same order as the original. Means are also provided by which single commands which require considerable processing may be executed in parallel on more than one of the processors, with each portion of the result coming from a different processor, yet maintaining the sequentiality of the output data stream. Processing speed is further enhanced by broadcasting global commands to all processors at once.

System for distributing command/data packets tagged by their unit

A method and device for improving the processing performance of a transform engine by off-loading the processing of those input polygons which have no more than a predetermined number of edges and decomposing such polygons into trapezoids which can be rendered by a scan conversion system. This is accomplished in accordance with the invention by reading edge data of each input polygon into a RAM and determining the relative positions of the Y coordinates of end points of each edge so that the beginning and end of each respective edge of the polygon in the Y direction may be determined. The polygon is then broken into trapezoids by reading in the respective beginning points of respective edges of the polygon and proceeding until the end point of one of the edges is reached. At the end of one edge, another edge of the polygon is read in, and the process continues until all trapezoids in the polygon have been drawn. Since trapezoids may be much more efficiently handled by the scan conversion system, a significant performance enhancement in the polygon processing is made possible in accordance with the invention.

Accelerated decomposition of small polygons into trapezoids

A technique for decomposing any simple or complex arbitrary polygon into a trapezoid having at least one edge parallel to the scan direction for more efficient scan conversion by rasterization circuitry. An input polygon is split into 'slabs', which are adjacent regions bounded by lines parallel to the scan direction. Initially the polygon is split at the y coordinate of every vertex to define the slabs. Then, for each slab, it is determined which edges are present in the slab and whether there are any unacceptable edge intersections. If an unacceptable edge intersection is found in a slab, that slab is broken into two or more slabs at the y coordinates of the intersection points of the edges. Each of the slabs is then processed independently. Once no unacceptable intersections are found in any slab, trapezoids are rendered from adjacent pairs of edges and sent to the rasterization circuitry. Since edge intersections may be accounted for in accordance with the invention, any input polygon, no matter how complex, may be correctly rendered in an efficient manner.

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Fort Collins, CO, United States of America

Bradley W Cain