Design and implementation of reciprocal unit
Dongdong Chen, Bintian Zhou, Zhan Nan Guo, Peter Nilsson · 2005
This paper presents the design and implementation of a reciprocal unit, in which the initial approximation of the reciprocal is obtained using a look-up table and a multiplication. How to create a look-up table efficiently is described in detail, and the error analysis for the ROMs of different sizes is also given in this paper. The presented design utilizes a 2/sup 7/ /spl times/ 16 bits ROM followed by two Newton-Raphson iterations. It takes 10 clock cycles to achieve the 52-bit accuracy approximation of the reciprocal of a double precision floating-point number.