FFT.rar_C语言FFT_fft 旋转因子_mips倒序_旋转因子

#ifndef __FFT_H__ #define __FFT_H__ #include<reg52.h> #include<intrins.h> #include <math.h> #include <stdlib.h> #define uchar unsigned char #define uint unsigned int #define N 1000 typedef struct { double real; double img; }complex; complex x[N],*W; int size_x = 0; //输入序列的大小 double PI; void add(complex a,complex b,complex *c) { c->real=a.real+b.real; c->img=a.img+b.img; } void mul(complex a,complex b,complex *c) { c->real=a.real*b.real - a.img*b.img; c->img=a.real*b.img + a.img*b.real; } void sub(complex a,complex b,complex *c) { c->real=a.real-b.real; c->img=a.img-b.img; } void change() { complex temp; unsigned short i=0,j=0,k=0; double t; for(i=0;i<size_x;i++) { k=i;j=0; t = (log(size_x)/log(2)); while((t--)>0) { j=j<<1; j|=(k & 1); k = k >> 1; } if(j>i) { temp = x[i]; x[i]=x[j]; x[j]=temp; } } } void initW() { int i; W=(complex*)malloc(sizeof(complex)*size_x); 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); } } void fft() { int i=0,j=0,k=0,l=0; complex up,down,product; change(); for(i=0;i<log(size_x)/log(2);i++) { l=1<<i; for(j=0;j<size_x;i+=2*l) { for(k=0;k<l;k++) { mul(x[j+k+l],W[size_x*k/2],&product); add(x[j+k],product,&up); sub(x[j+k],product,&down); x[j+k]=up; x[j+k+l]=down; } } } }