fffff.c

在ICCAVR 环境实现的fft,

#include <iom128v.h>
#include <math.h>
#define PI 3.1415926
#define qq PI/8

int dataR[]={5,5,5,5,0,0,0,0,5,5,5,5,0,0,0,0};
int dataI[16],w[32];


void FFT(int dataR[],int dataI[])
{int x0,x1,x2,x3,x4,x5,x6,xx;
 unsigned char i;
 int L,j,k,b,p;
 float TR,TI,temp;
/********** following code invert sequence ************/
for(i=0;i<16;i++)
{ x0=x1=x2=x3=x4=x5=x6=0;
x0=i&0x01; x1=(i>>1)&0x01; x2=(i>>2)&0x01; x3=(i>>3)&0x01;
//x4=(i>>4)&0x01; x5=(i>>5)&0x01; x6=(i>>6)&0x01;
xx=x0*8+x1*4+x2*2+x3;
dataI[xx]=dataR[i];
}
for(i=0;i<16;i++)
{ dataR[i]=dataI[i]; dataI[i]=0; }
/************** following code FFT *******************/
for(L=1;L<=4;L++) { /* for(1) */
b=1; i=L-1;
while(i>0) 
{b=b*2; i--;} /* b= 2^(L-1) */
for(j=0;j<=b-1;j++) /* for (2) */
{ p=1; i=4-L;
while(i>0) /* p=pow(2,7-L)*j; */
{p=p*2; i--;}
p=p*j;for(k=j;k<16;k=k+2*b) /* for (3) */
{ TR=dataR[k]; TI=dataI[k]; temp=dataR[k+b];
dataR[k]=dataR[k]+dataR[k+b]*cos(qq*p)+dataI[k+b]*sin(qq*p);
dataI[k]=dataI[k]-dataR[k+b]*sin(qq*p)+dataI[k+b]*cos(qq*p);
dataR[k+b]=TR-dataR[k+b]*cos(qq*p)-dataI[k+b]*sin(qq*p);
dataI[k+b]=TI+temp*sin(qq*p)-dataI[k+b]*cos(qq*p);
} /* END for (3) */
} /* END for (2) */
} /* END for (1) */
for(i=0;i<32;i++)
  {                        /* 只需要32次以下的谐波进行分析 */
w[i]=sqrt(dataR[i]*dataR[i]+dataI[i]*dataI[i]);
   if(!i)
   {
    w[i]=w[i]/64;
   }
  }
w[0]=w[0]/2;
} /* END FFT */

void main ()
  {
    FFT(dataR,dataI);
	while(1);
  }