| 摘要 |
PURPOSE:To keep the interchange ability between the present and conventional types of arithmetic logic operation circuits by adding the hardware to an arithmetic logic operation circuit in order to mask the input and output signals of the arithmetic logic circuit. CONSTITUTION:The output of a 16-bit multiplier 1 passes through a 1st mask circuit 4a, and the circuit 4a masks a specific bit of an input signal based on the contents of a mask circuit control register 5a. Therefore, the low order 16 bits are masked to '0' out of 32 bits of the output signal of the circuit 4a. Then this mask data is shifted to the right by a bt by a 32-bit ALU 2b in terms of arithmetic. This arithmetic result is temporarily inputted to a totalizing register 3b through a 2nd mask circuit 4b. Then the ALU 2b calculates the input data and the contents of a lst totalizing register 3a to add them to the register 3a. Thus this totalizing result is equal to that obtained by a DSPI. Then the interchangeability is kept between the present and conventional types of arithmetic logic operation circuits. |
