| 摘要 |
PURPOSE:To shorten the processing time and to reduce the amount of hardware by determining a positive or negative sign in accordance with the number of positive or negative values of three data in the absolute value form and the value of the last carry. CONSTITUTION:For example, when data A0 and B0 out of three data A0, B0 and C0 of data 1 in the absolute value form are negative and only data C. is positive, an inverting circuit 12 outputs data A, B, and C, where the fixed- point part of only data C0 is inverted to adders 10 and 11. The adder 11 performs addition of A+B+C+1, and the adder 10 performs addition of A+B+C. An inverting circuit 15 takes the addition value of the adder 10 as the input and inverts its value to output the result. A selecting circuit 13 selects the output of the inverting circuit 15 as the one's complement of A+B+C and outputs this output as a fixed-point part addition result 3. A sign calculating circuit 14 outputs the sign part addition result of the negative sign because only data C0 is positive and the last carry is 0. |
