Cache burst architecture for parallel processing, such as for image

Abstract

A parallel processing system for processing data matrices, such as images, is disclosed. The system includes a plurality of processing units, organized in four blocks of eight processing units per processing chip, and external cache burst memory, wherein each processing unit is associated with at least one column of the external memory. A barrel shifter connected between the memory and the processing units allows data to be shifted to adjacent processing chips, thus providing the means for connecting several of the chips into a ring structure. Further, digital delay lines are connected between the barrel shifter and the processing units, thus providing the capability of delaying, via a predetermined number of clock cycles, incoming column data. Each processing unit is provided with a nine bit cache memory. The system further includes a controller for each chip that sequences a burst of consecutive rows of a data matrix from the external cache burst memory, to be stored in either the cache memory associated with each of the processing units or routed directly to the processors included in each processing unit. The barrel shifters and the delay lines cooperate to bring horizontally and vertically displaced data points in the external memory to a single processing unit in a single clock cycle period. The controller decodes instructions stored in the external memory, wherein each processing unit receives the same instruction at any given cycle; this decoded instruction is valid for subsequent data bursts from external memory, thus providing the means for allowing instructions and data to be stored in the same external memory without a significant performance penalty. Where the width of an image is greater than the number of processing units, the image must be segmented to be stored in memory. An efficient method of relating column data across segment boundaries is thus provided, using the cache memory of selected processing units.