Report Number: CSL-TR-93-554
Institution: Stanford University, Computer Systems Laboratory
Title: Using a Floating-Point Multiplier's Internals for High-Radix
Division and Square Root
Author: Schwarz, Eric M.
Author: Flynn, Michael J.
Date: January 1993
Abstract: A method for obtaining high-precision approximations of
high-order arithmetic operations at low-cost is presented in
this study. Specifically, high-precision approximations of
the reciprocal (12 bits worst case) and square root (16 bits)
operations are obtained using the internal hardware of a
floating-point multiplier without the use of look-up tables.
The additional combinatorial logic necessary is very small
due to the reuse of existing hardware. These low-cost
high-precision approximations are used by iterative
algorithms to perform the operations of division and square
root. The method presented also applies to several other
high-order arithmetic operations. Thus, high-radix algorithms
for high-order arithmetic operations such as division and
square root are possible at low-cost.