| 摘要 |
PURPOSE:To detect an overflow with small hardware by detecting the overflow of multiplication with codes based on overflow information at the time of gener ating a partial product and overflow information at the time of accumulating the partial product. CONSTITUTION:This multiplier is provided with a multiplicand register 4 holding a multiplicand, a multiplier register 1 holding a multiplier and a partial product generation means 8 which decodes the held multiplier for respective bits while it obtains the partial product based on the mutiplicand and the Booth algorithm. An accumulation means 7 accumulating all the partial products obtained in the generation means 8 in decoding units, and an overflow detection means 9 detecting the overflow based on overflow information at the time of generating the partial product in respective decoding units and at the time of accumulating all the partial products are provided. Consequently, the overflow of multiplica tion with the codes is detected from overflow information at the time of generat ing the partial product and overflow information at the time of accumulating the partial product. Thus, the overflow which occurs at the time of multiplica tion can rationally be detected with small hardware. |
