Digital filter instruction and filter implementing the filter instruction

A digital filter instruction and filter implementing the filter instruction are disclosed. The filter instruction synthesizes a digital filter and includes an instruction field, a tap length field, a coefficient address field, a data header address field, a clear accumulator bit and an update bit. The filter instruction a concise instruction format to significantly decrease memory required, allow for instruction pipelining without branch penalty, and uses a circular buffer for the data so the data address pointer is only needed to be updated for the next input sample. The filter instruction may be used to implement FIR or IIR filters by using the options of pre-clear accumulator or pre/post storing accumulator results.