hello_led.c

在SOPC里实现了频谱分析

#include "system.h"
#include "alt_types.h"
#include <math.h>
#define N 2048

struct compx 
{ float real;
  float imag;
} compx;



struct compx x[N]; /*输入序列,变换核*/
struct compx W[N]={
    #include"wreal.dat"
};
float hanning[2048]={
    #include"hanning.dat"
};
float dis[2048];
int size_x=2048;
float PI=3.1416;        /*圆周率*/





struct compx EE(struct compx b1,struct compx b2)
{
        struct compx b3;
b3.real=b1.real*b2.real-b1.imag*b2.imag;
b3.imag=b1.real*b2.imag+b1.imag*b2.real;
return(b3);
}

void FFT(struct compx* xin,int n)
{
int f,m,LH,nm,k,i,j,L,p;
int le,B,ip;
struct compx t;
LH=n/2;  
f=n;
m=11;
for(L=m;L>=1;L--)    /*这里和时域的也有差别*/
{  
le=(1<<L);
B=le/2; /*每一级碟形运算间隔的点数*/
 for(j=0;j<=B-1;j++)
  {
   p=((1<<(m-L))*j);
   for(i=j;i<=N-1;i=i+le)
     { 
      ip=(i+B);   
      t=xin[i];
      xin[i].real=xin[i].real+xin[ip].real;
      xin[i].imag=xin[i].imag+xin[ip].imag;   
      xin[ip].real=xin[ip].real-t.real;
      xin[ip].imag=xin[ip].imag-t.imag;      
      xin[ip]=EE(xin[ip],W[p]);
     }
  }
}
 
/*变址运算*/

nm=n-2;    
j=n/2;
for(i=1;i<=nm;i++)
{
if(i<j){t=xin[j];xin[j]=xin[i];xin[i]=t;}
k=LH;
while(j>=k){j=j-k;k=k/2;}
j=j+k;
}
}
 

int main (void)
{
  int i=0;
  for(i=0;i<N;i++)
  {
    x[i].real=sin(2*PI*i/1500);
    x[i].imag=0;
  }
  i=0;
  for(i=0;i<2048;i++)
  {
    x[i].real=x[i].real*hanning[i];
  }
  i=0;
  FFT(&x,N);
  i=0;
  for(i=0;i<1024;i++)
  {
    dis[i]=x[i].real*x[i].real+x[i].imag*x[i].imag;
  }
  i=0;
  while(1);
  return 0;
}
/******************************************************************************
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