#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 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; 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); }逐行注释

#include<math.h> //头文件，包含数学函数库
#define FIRNUMBER 25 //滤波器长度
#define SIGNAL1F 1000 //信号1频率
#define SIGNAL2F 4500 //信号2频率
#define SAMPLEF 10000 //采样频率
#define PI 3.1415926 //圆周率
float InputWave(); //输入信号函数
float FIR(); //FIR滤波器函数

float fHn[FIRNUMBER]={ 0.0,0.0,0.001,-0.002,-0.002,0.01,-0.009, //FIR滤波器系数
-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 fXn[FIRNUMBER]={ 0.0 }; //FIR滤波器输入信号缓存
float fInput,fOutput; //输入输出信号
float fSignal1,fSignal2; //信号1和信号2的相位
float fStepSignal1,fStepSignal2; //信号1和信号2的步长
float f2PI; //2倍圆周率
int i; //循环变量
float fIn[256],fOut[256]; //输入输出信号缓存
int nIn,nOut; //输入输出信号缓存指针

main() { //主函数
nIn=0; nOut=0; //初始化指针
f2PI=2*PI; //计算2倍圆周率
fSignal1=0.0; //初始化信号1相位
fSignal2=PI*0.1; //初始化信号2相位
fStepSignal1=2*PI/30; //计算信号1步长
fStepSignal2=2*PI*1.4; //计算信号2步长
while ( 1 ) //循环
{
fInput=InputWave(); //获取输入信号
fIn[nIn]=fInput; //将输入信号存储到缓存中
nIn++; nIn%=256; //更新指针
fOutput=FIR(); //使用FIR滤波器处理输入信号
fOut[nOut]=fOutput; //将输出信号存储到缓存中
nOut++; //更新指针
if ( nOut>=256 ) //如果输出缓存已满
{
nOut=0; //重置指针
}
}
}

float InputWave() { //输入信号函数
for ( i=FIRNUMBER-1;i>0;i-- ) //将输入信号依次存储到FIR滤波器的输入缓存中
fXn[i]=fXn[i-1];
fXn[0]=sin(fSignal1)+cos(fSignal2)/6.0; //构造复合信号
fSignal1+=fStepSignal1; //更新信号1相位
if ( fSignal1>=f2PI ) //如果信号1相位已经超过一个周期
fSignal1-=f2PI; //将其减去一个周期
fSignal2+=fStepSignal2; //更新信号2相位
if ( fSignal2>=f2PI ) //如果信号2相位已经超过一个周期
fSignal2-=f2PI; //将其减去一个周期
return(fXn[0]); //返回输入信号
}

float FIR() { //FIR滤波器函数
float fSum; //初始化累加器
fSum=0; //清零累加器
for ( i=0;i<FIRNUMBER;i++ ) //依次使用FIR滤波器的系数和输入信号进行卷积
{
fSum+=(fXn[i]*fHn[i]); //累加卷积结果
}
return(fSum); //返回卷积结果
}

//注释中的“软件断点”是一个提示，建议在此处加入一个断点以便调试。