| 摘要 |
PURPOSE:To attain a direct calculation of the input data of an unpack style through a decimal addition/subtraction circuit, by using a PG generating circuit which produces a carry transmission function and a carry production function from two binary code decimal data. CONSTITUTION:A decimal addition/subtraction circuit is provided with the 1st input circuit 4, the 2nd input circuit 5, a binary adder 6 and a decimal correction circuit 7. The circuit 4 adds 6 to each digit of the input data A and supplies then to the adder 6 if an addition is indicated from an addition/subtraction indicating circuit 80. In a subtraction mode the circuit 5 inverts an operand B and supplies it to the adder 6. A PG generating circuit 90 uses the outputs of circuits 4 and 5 to produce both a carry transmission function and a carry production function for each digit with an algorithm similar to a conventional one. A carry generating circuit 10 supplies a carry transmission function Pi and a carry production function Gi for each digit from the circuit 90 and produces the carry information Ci for each addition unit (digit unit). |
