一种基于贪婪算法的CORDIC改进算法

摘要

This paper proposes a new modified algorithm under rotation mode of CORDIC( Coordinate Rota-tion Digital Computer) to save time and areas in conventional CORDIC, which can be used to take the place of the LUTs in DDS ( Direct Digital Synthesizer) to calculate the sine or cosine. A modified parallel algorithm based on Greedy Algorithm is put forward to convert the conventional serial to parallel and reduce the irritation number and save areas. And the new method can be applied in hardware implementation for functions based on trigonometric function. The simulation shows that the modified algorithm can get higher precision compared with the conventional one on premise of the same irritation number. Finally, the modi-fied CORDIC architecture is implemented on Xilinx Spartan-3E FPAG Field Programmable Gate Array). The modified algorithm leads to 28% and 25% area reduction for Slices and LUTs ( Look Up Tables) re-spectively.%针对传统串行坐标旋转数字计算方法( CORDIC )耗时且占用较多资源的缺点，提出了一种旋转模式下CORDIC算法的新型改进算法，该改进算法可用来代替直接数字频率合成器( DDS)查找表进行正余弦的计算。通过采用贪婪算法实现对CORDIC旋转方向与旋转角度的优化，从而可以达到串行转并行和减少迭代次数、节约资源的目的。该算法可以应用于三角函数的复杂函数的硬件实现中。仿真结果表明，在迭代次数相同的情况下，改进算法较传统算法可以获得更高的精度。最后，在Xilinx FPGA的Spartan-3 E芯片上实现了改进的CORDIC结构。与传统CORDIC算法相比，在运算精度为10-5时，可以节省Slices、LUTs( Look Up Tables)资源分别为28%和25%。