Double Precision Hybrid-Mode Floating-Point FPGA CORDIC Co-processor

FPGA chips have become a promising option for accelerating scientific applications, which involve many floating-point transcendental functions, such as sin, log, exp, sqrt and etc. In this paper, we present a 64-bit ANSI/IEEE floating-point CORDIC co-processor on FPGA, providing all known CORDIC functions. And there is no 64-bit CORDIC implementation on FPGA known to us. We propose a hybrid-mode CORDIC algorithm, combining hybrid rotation angle methods with argument reduction algorithm to reduce hardware area usage and meanwhile keep unlimited convergence domain for any floating-point inputs of the functions. Our hybrid-mode CORDIC co-processor is organized into three phases, argument reduction, CORDIC calculation and normalization with 69 pipeline stages for FPGA implementation. The synthesis results show the clock frequency can reach 173 MHz on Xilinx Virtex5 FPGA. Comparing to general-purpose microprocessor in three scientific program kernels, the CORDIC co-processor can achieve a maximum speedup of 49.3 times, 28.7 times in average.