A Trigonometric Function Instruction Set Extension Method Based on RISC-V
Zhanyuan Gao, Laiping Zhao, Haonan Chen · 2022
Facing the ever-increasing demands of microprocessors for computing power nowadays, trigonometric functions, as the basis of various algorithms, have problems with latency, resource overhead and power consumption in traditional software or coprocessor schemes. In this paper, a lightweight RISC-V standard microprocessor is designed. In addition, the optimization of the CORDIC algorithm realizes a low-latency and high-precision trigonometrical kernel-level accelerator， and the instruction set is extended. The experiment shows that the instruction expansion method used in this paper can reduce the iteration cycle by more than 92% on average compared with the pure software solution and it can reduce the error and the iteration cycle by 33% and 46% on average compared with the solution of the traditional CORDIC algorithm. Under the SMIC180nm technology, the extension instruction consumes 3.9k equivalent gates and only occupies 13.9% of the processor area. The RISC-V processor after extending trigonometric function still has several advantages in area and main frequency relative to the ARM processor in the same period.