Programmable index hashing function circuit and method of optimisation, for use with a cache memory on a microprocessor

摘要

A programmable index hashing function is designed that allows the index hashing function to be programmed after the microprocessor has been fabricated. The index hashing function may be "tuned" by running an application on the microprocessor and observing the performance of the cache memory based on the type of index hashing function used. The index hashing function may be programmed by several methods. These include EPROMS, EEPROMS, laser blown fuses, electrically blown fuses and remote diagnostic registers. The circuit comprises a set of AND gates, and XOR gates, a hashing mask (which is programmable) and a memory array. The inputs to The AND gate consist at the hashing mask and halt at the memory array bits. The output from the AND gates are combined with the other half at the memory array bits in the XOR gates to produce a hashed value.