Adaptive CORDIC: Using Parallel Angle Recoding to Accelerate CORDIC Rotations

The CORDIC algorithm is used in the evaluation of a wide variety of elementary functions. It is a simple and elegant method, but it suffers from the problem of long latency. The angle recoding method is able to reduce the number of iterations by more than 50%, but its implementation in hardware requires a large increase in cycle time, to accommodate its complex angle selection function. This restricts its use to those cases where the angle of rotation is fixed and known in advance, so that the method can be applied off-line. This paper, presents a simpler implementation of the angle selection scheme that allows the angle recoding method to be used dynamically for any arbitrary angle of rotation. The method also has the advantage that all the angle constants are found in parallel, in a single step, without having to perform successive CORDIC iterations.