Parallel unidirectional division algorithms and implementations

This paper describes the design of algorithms for unidirectional division. Rather than the conventional, restoring or nonrestoring, divisions which re quire both subtraction and addition operations. alternately, during the pro cess of division, the proposed method needs only one direction, either subt raction or addition, but not both, during the process of the division. If b oth operands, dividend and divisor, are positive or negative, only subtract ion is used. However, if one is positive and the other negative, only addit ion is applied. This method can skip zero bits in dividend, and consequentl y the number of additions/subtractions is expected to be less than conventi onal division, about (3/5)n compared to 3/2n (or n if MUXes are used) for r estoring or to n for nonrestoring. In addition, unidirectional division can be processed in parallel or in semi-parallel, if the bit length of the div idend is long enough. This method is also easily extended to apply to two's complement divisions. The conversion of the quotient to binary is not requ ired for the proposed method, (in which nonrestoring division is necessaril y converted back to binary code in order to match other operations, because the resulting quotient is expressed by signed-digit code).