Cache organization—direct mapped cache

Abstract

The invention provides for cache organization of texture information and a method and apparatus for accessing cached texture information and an index for cached information. Texels are represented in two dimensions and stored in groups referred to as tiles. Cache is configured to contain multiple tiles of texture image data, each tile being stored as a line in the cache. A cache line can be multidimensional (e.g., two or three or more dimensions) and may be viewed as an identifiable storage element in the cache. Memory may consist of a plurality of cache lines. Direct mapped cache may be utilized wherein each DRAM location maps to a single cache line. A tag table contains the tag information for all tiles currently stored in cache. A portion of the texel information may be utilized as an index assigned to a specific cache line. Another portion of the tag information identifies the tile currently stored in cache. A portion of the S bits and a portion of the T bits are utilized as the index and tile information. The tags may be organized into sections (referred to as tag banks) with the cache lines interleaved in two dimensions across the tag banks. Additionally, when mipmapping, the level of detail may be specified as part of the tag information. Cache access requests that are not currently active may also be stored in an interleaved list or queue until they are completed.