Patent ID: 8166087

Claim:
A microprocessor comprising: a filter operation circuit which executes an infinite impulse response (IIR) filter operation by using a plurality of filter coefficients, and outputs one sample of data subjected to said IIR filter operation and a transfer data to be used in a next IIR filter operation; a first source register which provides the plurality of filter coefficients to be used in the IIR filter operation to the filter operation circuit; a second source register which provides a past transfer data to the IIR filter operation circuit, and is overwritten with a new transfer data output from the filter operation circuit; and a third source register which holds a plurality of samples of data to be subjected to the IIR filter operation, and provides the plurality of data to be subjected to the IIR filter operation to the filter operation circuit, wherein a storage area of the third source register for storing at least one sample to be subjected to the IIR filter operation is overwritten with the data subjected to the IIR filter operation output from the filter operation circuit, and wherein the third source register cyclically shifts the data held in the third source register in response to overwriting with said data output from the filter operation circuit.