[DSP编程] 请教一下关于FIR滤波器的程序问题

#include<math.h>



#define FIRNUMBER 25

#define SIGNAL1F 1000

#define SIGNAL2F 4500

#define SAMPLEF  10000

#define PI 3.1415926



float InputWave();

float FIR();



//float fHn[FIRNUMBER]={ 0.0,0.0,0.001,-0.002,-0.002,0.01,-0.009,

//                       -0.018,0.049,-0.02,0.11,0.28,0.64,0.28,

//                       -0.11,-0.02,0.049,-0.018,-0.009,0.01,

//                       -0.002,-0.002,0.001,0.0,0.0

//                     };

float fHn[FIRNUMBER]={0.0,0.0,-0.001,-0.003,-0.009,-0.017,-0.022,

                      -0.012,0.021,0.079,0.147,0.204,0.226,0.204,

                      0.147,0.079,0.021,-0.012,-0.022,-0.017,-0.009,

                      -0.003,-0.001,0.0,0.0

                      };

float fXn[FIRNUMBER]={ 0.0 };

float fInput,fOutput;

float fSignal1,fSignal2;

float fStepSignal1,fStepSignal2;

float f2PI;

int i;

float fIn[256],fOut[256];

int nIn,nOut;



main()

{

        nIn=0; nOut=0;

        f2PI=2*PI;

        fSignal1=0.0;

        fSignal2=PI*0.1;

        fStepSignal1=2*PI/30;

//        fStepSignal2=2*PI*1.4;

        fStepSignal2=2*PI/200;  /*1.4;*/

        while ( 1 )

        {

                fInput=InputWave();

                fIn[nIn]=fInput;

                nIn++; nIn%=256;

                fOutput=FIR();

                fOut[nOut]=fOutput;

                nOut++;                                /* 请在此句上设置软件断点 */

                if ( nOut>=256 )

                {

                        nOut=0;                

                }

        }

}



float InputWave()

{

        for ( i=FIRNUMBER-1;i>0;i-- )

                fXn[i]=fXn[i-1];

        fXn[0]=sin(fSignal1)+cos(fSignal2)/6.0;

        fSignal1+=fStepSignal1; 

        if ( fSignal1>=f2PI )        fSignal1-=f2PI;

        fSignal2+=fStepSignal2;

        if ( fSignal2>=f2PI )        fSignal2-=f2PI;

        return(fXn[0]);

}



float FIR()

{

        float fSum;

        fSum=0;

        for ( i=0;i<FIRNUMBER;i++ )

        {

                fSum+=(fXn[i]*fHn[i]);

        }

        return(fSum);

}