Memory interface for functional unit of integrated system allowing access to dedicated memory and shared memory, and speculative generation of lookahead fetch requests

Abstract

A memory interface for an integrated system is presented which allows simultaneous, transparent access to multiple external memories coupled thereto. The memory interface resides within a functional unit of the integrated system and includes multiple memory ports, at least one of which is coupled to dedicated memory and one port to shared memory. The dedicated memory comprises private memory for the functional unit, while the shared memory is common memory coupled to the functional unit and other functional units of the integrated system. The memory interface has a controller for forwarding memory fetch requests generated by requesting units within the functional unit to the proper memory port as determined at system initialization. A lookahead request generator is employed for generating speculative lookahead fetch requests within the memory interface using information on received memory fetch requests and known memory access patterns. The lookahead fetch requests retrieve data from external memory in anticipation of actual memory fetch requests being generated.