Advanced Components in the Variable Precision Floating-Point Library

Optimal reconfigurable hardware implementations may require the use of arbitrary floating-point formats that do not necessarily conform to IEEE specified sizes. We have previously presented a variable precision floating-point library for use with reconfigurable hardware. We recently added three advanced components: floating-point division, floating-point square root and floating-point accumulation to our library. These advanced components use algorithms that are well suited to FPGA implementations and exhibit a good tradeoff between area, latency and throughput. The floating-point format of our library is both general and flexible. All IEEE formats, including 64-bit double-precision format, are a subset of our format. All previously published floating-point formats for reconfigurable hardware are a subset of our format as well. The generic floating-point format supported by all of our library components makes it easy and convenient to create a pipelined, custom datapath with optimal bitwidth for each operation. Our library can be used to achieve more parallelism and less power dissipation than adhering to a standard format. To further increase parallelism and reduce power dissipation, our library also supports hybrid fixed and floatingpoint operations in the same design. The division and square root designs are based on table lookup and Taylor series expansion, and make use of memories and multipliers embedded on the FPGA chip. The iterative accumulator utilizes the library addition module as well as buffering and control logic to achieve performance similar to that of the addition by itself. They are all fully pipelined designs with clock speed comparable to that of other library components to aid the designer in implementing fast, complex, pipelined designs.