HIGH-SPEED VIDEO FRAME BUFFER USING SINGLE PORT MEMORY CHIPS WHERE PIXEL INTENSITY VALUES FOR DISPLAY REGIONS ARE STORED AT CONSECUTIVE ADDRESSES OF MEMORY BLOCKS

摘要

In standard display systems pixel data are stored in the frame buffer such that all data related to a pixel (both intensity values and non-display data as masks, Fast Clear etc.) are stored in a memory word; consecutive pixels of a line are stored in subsequent memory words. This data arrangement causes several memory accesses to be necessary for operations as drawing etc. on a set of neighbouring pixels. The present invention speeds up such operations by subdividing the display area in (rectangular) blocks, whose pixel data are stored in corresponding blocks of subsequent memory words. For each pixel, display data only are stored in a block, and non-display data are stored elsewhere, so that burst access mode can be used for accessing a set of neighbouring pixel display data in a single operation. The arrangement based on rectangular blocks is particularly advantageous for writing triangles, vectors etc. Each block is preferably stored across interleaved memory banks, that may be accessed in parallel for rendering and display. Dual bank operation (opening two pages at once) can be effected according to a checker-board block allocation, which still improves triangle and vector management. The invention is particularly suitable for SDRAM arrays having a single access port.