Abstract: A microprocessor with multiple stream prefetch engines each executing a stream prefetch instruction to prefetch a complex data stream specified by the instruction in a manner synchronized with program execution of loads from the stream is provided. The stream prefetch engine stays at least a fetch-ahead distance (specified in the instruction) ahead of the program loads, which may randomly access the stream. The instruction specifies a level in the cache hierarchy to prefetch into, a locality indicator to specify the urgency and ephemerality of the stream, a stream prefetch priority, a TLB miss policy, a page fault miss policy, a protection violation policy, and a hysteresis value, specifying a minimum number of bytes to prefetch when the stream prefetch engine resumes prefetching. The memory subsystem includes a separate TLB for stream prefetches; or a joint TLB backing the stream prefetch TLB and load/store TLB; or a separate TLB for each prefetch engine.

Abstract: A method for simulating fog in 3D graphics rendering applications correctly computes fogged pixel colors even in graphics scenes where two surfaces overlap and the frontmost surface is partially transparent. The method computes the fog for each surface according to the following formula: ƒF atop A, where ƒ is the amount of fog, F is the color of the fog, and A is the color of the pixel being fogged. Each fogged surface can be rendered independently to a separate image layer, called a fogged image layer. The graphics rendering system can then simulate the motion of a fogged image layer by moving the fogged layer in an (x,y) plane without re-computing the fogged pixels, or by moving the fogged layer in the z-direction and independently re-computing the moving fogged layer with a new value for the amount of fog applied to the image layer.