Method for branching to an instruction in a computer program at a memory

Abstract

A method for searching for keys of arbitrary width in a table in a memory of a computer system by repeatedly executing lookup instructions on a lookup processor. The lookup processor executes a lookup instruction to find a key in a table. The execution of the lookup instruction results in a key being found, or a key not being found. If the key is not found, the process is requeued by a scheduler with the program counter register for the process pointing to the instruction immediately following the lookup instruction, i.e., the next instruction. In the event the key is found in the table, the entry in the table associated with the key contains the memory address of the next instruction to be executed. This memory address is loaded into the program counter register associated with the process in which the lookup instruction was executed. The scheduler requeues the process, later dequeues it, and the instruction pointed to by the program counter register is fetched by an instruction fetch unit. A dispatcher sends the process to the appropriate processor for execution of the next instruction. In this way, a branch to any instruction in the process can be performed. The instruction pointed to by the PC register can be another lookup instruction in the process. In this way, multiple lookup instructions can be sequentially executed, each specifying a different portion of a key of arbitrary width, or each specifying a particular key in a sequence of keys being searched for.