FFT.zip_FFT核_fft nios_nios fft_nios实现FFT

#include"stdio.h" #include"math.h" #define N 1024 unsigned int size_x; double PI; typedef struct { double real; double img; }complex; complex x[N]; void fft(); void initW(); complex add(complex a,complex b); complex sub(complex a,complex b); complex mult(complex a,complex b); void fft() { unsigned int L,j,B,K; for(L=0;L<log(size_x)/log(2);L++) //分级运算 { B=1<<L; for(j=0;j<size_x;j+=2*B) //每个蝶形间隔 { for(k=0;k<B;k++) { x[j+k+B] = mult(x[j+k],x[j+k+B]); x[j+k] = add(x[j+k],x[j+k+B]); x[j+k+B] = sub(x[j+k],x[j+k+B]); } } } } /*初始化变化核*/ void initW() { unsigned int i; complex W[1024]; for(i=0;i<size_x;i++) { W[i].real=cos(2*PI/size_x*i); W[i].img=-1*sin(2*PI/size_x*i); } } //加法 complex add(complex a,complex b) { complex result; result.real = a.real + b.real; result.img = a.img + b.img; return result; } //减法 complex sub(complex a,complex b) { complex result; result.real = a.real - b.real; result.img = a.img - b.img; return result; } //乘法 complex mult(complex a,complex b) { complex result; result.real = a.real * b.real; result.img = a.img * b.img; return result; }