VPFPAP: A Special-Purpose VLIW Processor for Variable-Precision Floating-Point Arithmetic

Many scientific computing applications require efficient variable-precision floating-point arithmetic. This paper presents a special-purpose Variable-Precision Floating-Point Arithmetic Processor (VPFPAP) based on Very Large Instruction Word (VLIW) structure. The proposed processor uses a unified hardware structure, equipped with multiple custom basic variable-precision arithmetic units, to implement various variable-precision algebraic and transcendental functions. The performance is improved by the explicitly parallel technology of VLIW instruction and by dynamically varying the precision of intermediate computation. Finally, we create a prototype of VPFPAP unit into a Xilinx Virtex-6 XC6VLX760-2FF1760 FPGA chip. The experimental results show that our design, based on FPGA running at 253 MHz, outperforms the approach of a software-based library running on an Intel Core i3 530 CPU at 2.93 GHz by a factor of 5-38X for basic variable precision arithmetic operations and elementary functions.