| 摘要 |
PURPOSE:To reduce the number of operation cycles and to rapidly execute multiplication by scanning a multiplier, adding a multiplicand to a partial product only a digit having '1' and collectively shifting a multiplicant by means of a barrel shifter for digits having continuous '0's. CONSTITUTION:Assuming least significant bit out of a multiplier B stored in a multiplier register 2 is Bk (Bk=1, 0<=k<=n-1), '1' is inputted to the k-th digit from the vertical lest significant digit of the barrel shifter 4 from the multiplier B through a control signal circuit 5. The output of multiplicand A stored in a multiplicand register 1 is shifted to the left by (k) bits by means of the barrel shifter 4, the shifted value is added to the contents of a partial product register 3 by an adder 6 and the added result is sent and stored to/in a partial product register 3. The, the bit Bk stored in the register 2 is reset to '0' by a control signal 10. Consequently, the product Y of 2n bits to be the multiplied result is obtained in the register 3 only by repeating the operating number of times corresponding to the number of '1' in the multiplier.
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