Instruction masking in providing instruction streams to a processor

摘要

A circuit is provided to provide instruction streams to a processing device: embodiments of the circuit are appropriate for use with RISC CPUs, whereas other embodiments are usable with other processing devices, such as small processing devices used in field programmable array. The circuit receives an external instruction stream 1 which provides a first set of instruction values, and has a memory which contains a second set of instruction values. Two or more outputs provide instruction streams 13, 14 to the processing device 3. The circuit has a control input 12 in the form of a mask which causes a selection means 11 to allocate bits from the first and second sets of instruction values to different instruction streams to the processing device.