Adaptive selection of an index in a texture cache

For a specified application, there is an opportunity to improve cache performance by smart choosing of index bits of a cache. A texture cache for texture mapping of 3D computer graphics is an example. Texel (texture pixel)-access characteristics for texture mapping are dependent on the rasterization order of a polygon. In this paper, we introduce A-index, a method to reduce memory bandwidth required for fetching texture image data by reducing cache miss through adaptive selection of an index according to span direction of a rasterizer. By designing a texture mapping hardware including a texture cache, it is verified that the number of cache misses and the number of total cycles are reduced by 21.6% and 8.8% for rendering of textured scenes. In addition, we show that the number of cache misses in a texture cache can be estimated more accurately by calculating intra-span replacement when the proposed A-index is used.