FFT算法的DSP实现

//1. 主程序FFT.c
#include "math.h"
#define Sample_Numb 256   // FFT点数
#define S1_Freq 60       //信号1频率
#define S2_Freq 180      // 信号2频率
#define SampleFreq 800   //采样率
#define pi 3.1415926
#define M log(Sample_Numb)/log(2) //变更FFT点数修改fft子程序方便的需要
int SignalInput[Sample_Numb];//输入信号，S=S1+S2
float FFT_Re[Sample_Numb];// FFT实部
float FFT_Im[Sample_Numb];//FFT虚部
float FFT_W[Sample_Numb];    //功率谱
float sin_tab[Sample_Numb];
float cos_tab[Sample_Numb];
void init_fft_tab();
void input_data();
void fft(float datar[Sample_Numb],float datai[Sample_Numb]);


 void init_fft_tab(void) //输入波形的初始化
  {
   float wt1;
   float wt2;
   int i;
   for (i=0;i<Sample_Numb;i++)
    {
wt1=2*pi*i*S1_Freq;
wt1=wt1/SampleFreq;


wt2=2*pi*i*S2_Freq;
wt2=wt2/SampleFreq;
SignalInput[i]=(cos(wt1)+cos(wt2))/2*100;
}
  }


  void FFT_WNnk(void)//蝶形运算系数表计算
   {
    int i;
for(i=0;i<Sample_Numb;i++)
{
 sin_tab[i]=sin(2*pi*i/Sample_Numb);
 cos_tab[i]=cos(2*pi*i/Sample_Numb);
}
}


void fft(float datar[Sample_Numb],float datai[Sample_Numb])
{
 int x0,x1,x2,x3,x4,x5,x6,x7,xx;
 int i,j,k,b,p,L;
 float TR,TI,temp;
 
 for(i=0;i<Sample_Numb;i++)   
 {
   x0=x1=x2=x3=x4=x5=x6=0;
   x0=i&0x01;x1=(i/2)&0x01;x2=(i/4)&0x01;x3=(i/8)&0x01;
   x4=(i/16)&0x01;x5=(i/32)&0x01;x6=(i/)&0x01;x7=(i/128)&0x01;
   xx=x0*128+x1*+x2*32+x3*16+x4*8+x5*4+x6*2+x7;
   datai[xx]=datar[i];
 }
 for(i=0;i<Sample_Numb;i++)
 {
    datar[i]=datai[i];datai[i]=0;
 }


 for(L=1;L<=M;L++)
  {
    b=1;i=L-1;
while(i>0)
{
b=b*2;i--;
}
for(j=0;j<=b-1;j++)
{
p=1;i=M-L;
while(i>0) { p=p*2;i--;}  
p=p*j;


        for(k=j;k<Sample_Numb;k=k+2*b)
{
  TR=datar[k];TI=datai[k];temp=datar[k+b];
  datar[k]=datar[k]+datar[k+b]*cos_tab[p]+datai[k+b]*sin_tab[p];
  datai[k]=datai[k]-datar[k+b]*sin_tab[p]+datai[k+b]*cos_tab[p];
  datar[k+b]=TR-datar[k+b]*cos_tab[p]-datai[k+b]*sin_tab[p];
  datai[k+b]=TI+temp*sin_tab[p]-datai[k+b]*cos_tab[p];
    }
  }
}


for(i=0;i<Sample_Numb/2;i++)
{
  FFT_W[i]=sqrt(datar[i]*datar[i]+datai[i]*datai[i]);
}
}


void main()
{
  int i;
  init_fft_tab();
  FFT_WNnk();
  for (i=0;i<Sample_Numb;i++)
   {
     FFT_Re[i]=SignalInput[i];
FFT_Im[i]=0.0f;
FFT_W[i]=0.0f;
}
fft(FFT_Re,FFT_Im);
while(1);
 }

//2. CMD文件
MEMORY {
   DATA:       origin = 0x6000,        len = 0x4000
   PROG:       origin = 0x200,         len = 0x5e00
   VECT:       origin = 0xd000,        len = 0x100
}


SECTIONS
{
    .vectors: {} > VECT
    .trcinit: {} > PROG
    .gblinit: {} > PROG
     frt:     {} > PROG
    .text:    {} > PROG
    .cinit:   {} > PROG
    .pinit:   {} > PROG
    .sysinit: {} > PROG
    .bss:     {} > DATA
    .far:     {} > DATA
    .const:   {} > DATA
    .switch:  {} > DATA
    .sysmem:  {} > DATA
    .cio:     {} > DATA
    .MEM$obj: {} > DATA
    .sysheap: {} > DATA
    .stack:   {} > DATA
    .sysstack {} > DATA
}