NATIVE LOOKUP INSTRUCTION FOR FILE-ACCESS PROCESSOR SEARCHING A THREE-LEVEL LOOKUP CACHE FOR VARIABLE-LENGTH KEYS

A processor natively executes lookup instructions. The lookup instruction is decoded to determine which general-purpose register (GPR) contains a pointer to a lookup key in a buffer. A variable-length key is read from the buffer and hashed to generate an index into a first-level cache and a hashed tag. An address of a bucket of entries for the index is generated and tags from these entries are read and compared to the hashed tag. When an entry matches the hashed tag, a second-level entry is read. A stored key from the second-level entry is compared to the input key to determine a match. The addresses of the matching second-level and first-level entries are written to GPR's specified by operands decoded from the lookup instruction. When the key or entry data is long, the second-level entry also contains a pointer to a key extension or data extension in a third-level cache.