A CORDIC with Unified Rotation Strategy

摘要

CORDIC (Coordinate Rotation Digital Computer) is an iterative algorithm which is used to calculate mathematical functions such as trigonometric, hyperbolic, exponential functions and so on. The iterative procedure of conventional CORDIC is time-consuming due to its inadequate rotation strategy. Recently, some improved rotation strategies are proposed to reduce dispro-portionate rotations, which can significantly reduce about 30% to 60% of the iterative procedure for CORDIC algorithm. However, the improved rotation strategies can only be used for a few functions, since they only design to be compatible with circular coordinate system and rotation mode of CORDIC algorithm. In order to overcome such difficulty, this paper presents a unified rotation strategy to enable the functions of the improved rotation strategies for different coordinate systems and operating modes of the CORDIC algorithm. The proposed rotation strategy contains two components which are unified coarse rotation and unified precise rotation, which can drastically reduce disproportionate rotations meanwhile it can maintain higher calculation precision than conventional approaches.