Method and apparatus for automatically designing logic circuit, and multiplier

摘要

In the case where a multiplier factor is a constant, if the number of the bits having the value of 1 in the multiplier factor is 3 or more and if it is larger than the number of the bits having the value of 0, a circuit for performing multiplication by using the logic NOT number of the multiplier factor, which is obtained by inverting all the bits in the multiplier factor by the logic NOT operation is generated. If the number of the bits having the value of 1 in the multiplier factor is 3 or more and if it is smaller than the number of the bits having the value of 0, the multiplier factor is divided so that an adder for adding partial products forms a well-balanced binary tree. Conversely, if the number of the bits having the value of 1 in the multiplier factor is 2 or less, an add shift multiplier for calculating partial products only with respect to the bits having the value of 1 is generated.