Decimal floating-point division using Newton-Raphson iteration

Abstract

Decreasing feature sizes allow additional functionality to be added to future microprocessors to improve the performance of important application domains. As a result of rapid growth in financial, commercial, and Internet-based applications, hardware support for decimal floating-point arithmetic is now being considered by various computer manufacturers and specifications for decimal floating-point arithmetic have been added to the draft revision of the IEEE-754 Standard for Floating-Point Arithmetic (IEEE-754R). This work presents an efficient arithmetic algorithm and hardware design for decimal floating-point division. The design uses an optimized piecewise linear approximation, a modified Newton-Raphson iteration, a specialized rounding technique, and a simplified combined decimal incrementer/decrementer. Synthesis results show that a 64-bit (16-digit) implementation of the decimal divider, which is compliant with IEEE-754R, has an estimated critical path delay of 0.69 ns when implemented using LSI Logic's 0.11 micron gflx-p standard cell library.