Bus-based cache architecture

Abstract

Digital signal processors often operate on two operands per instruction, and it is desirable to retrieve both operands in one cycle. Some data caches connect to the processor over two busses and internally uses two or more memory banks to store cache lines. The allocation of cache lines to specific banks is based on the address that the cache line is associated. When two memory accesses map to the same memory bank, fetching the operands incurs extra latency because the accesses are serialized. An improved bank organization for providing conflict-free dual-data cache access—a bus-based data cache system having two data buses and two memory banks—is disclosed. Each memory bank works as a default memory bank for the corresponding data bus. As long as the two values of data being accessed belong to two separate data sets assigned to the two respective data buses, memory bank conflicts are avoided.