FPGA-oriented evaluation algorithm for exponential and logarithm functions
Shengmei Mou, Li Zhaogang · Computer Engineering and Applications Journal · 2011
CORDIC algorithm has been widely used for efficient evaluation of transcendental functions in hardware,but its generality prevents it to be optimized according to a certain function.A unified evaluation algorithm for exponential and logarithm function called LnE is proposed.It can be implemented only by shift and addition with linear convergence speed just as CORDIC algorithm does,but shows great advantages over CORDIC algorithm.LnE only needs x datapath and y datapath, and addition is needed independent of iteration coefficients di during all the iteration,which can reduce the cost of control. Moreover,LnE avoids the process of scale factor compensation and can converge without repeating some iteration.So,the number of iteration and cost of each iteration in LnE are both less than those of CORDIC,which can spare at least 1/3 of the area estate compared to CORDIC algorithm.