Open-source variable-precision floating-point library for major commercial FPGAs

Abstract

There is increased interest in implementing floating-point designs for different precisions that take advantage of the flexibility offered by Field-Programmable Gate Arrays (FPGAs). In this article, we present updates to the Variable-precision FLOATing Point Library (VFLOAT) developed at Northeastern University and highlight recent improvements in implementations for implementing reciprocal, division, and square root components that scale to double precision for FPGAs from the two major vendors: Altera and Xilinx. Our library is open source and flexible and provides the user with many options. A designer has many tradeoffs to consider including clock frequency, total latency, and resource usage as well as target architecture. We compare the generated cores to those produced by each vendor and to another popular open-source tool: FloPoCo. VFLOAT has the advantage of not tying the user's design to a specific target architecture and of providing the maximum flexibility for all options including clock frequency and latency compared to other alternatives. Our results show that variable-precision as well as double-precision designs can easily be accommodated and the resulting components are competitive and in many cases superior to the alternatives.