本文档里含有诸多c++文件，其功能实现有FIR滤波，IIR滤波，，还有正弦曲线，还实现了128点FFT，DFT-This document contains a lot of c++ file, its function to achieve a FIR filter, IIR filtering, as well as the sine curve, but also to achieve a 128-point FFT, DFT