[分享] 分享MSP430单片机实现的FIR滤波器C语言程序

灞波儿奔 2019-10-8 14:21 楼主

#include <stdio.h>

#define FRAME       180
short int h[19] = {
   399,-296,-945,-1555,
   -1503,-285,2112,5061,
   7503,8450,7503,5061,
   2112,-285,-1503,-1555,
   -945,-296,399
};
static short int nBuff[FRAME + 20];
void LowpassFilter(short int nIn[],short int nOut[],int nLen,short int h[]);
void main()
{
   FILE *m_pInput;
   FILE *m_pOutput;
short int input[FRAME];
   short int output[FRAME];
   int count;

   // 打开输入文件
   if((m_pInput = fopen("input.wav", "rb")) == NULL)
   {
       return;
   }
   //打开输出文件
   if((m_pOutput = fopen("output.wav", "wb")) == NULL)
   {
       return;
   }
count = 0;
   while( fread(&input[0], sizeof(short int), FRAME, m_pInput) == FRAME)
   {
       printf("Frame =%d\r", count++);
       //滤波处理
       LowpassFilter(input,output,19,h);
       //将滤波后的数据写到文件里
       fwrite(output, sizeof(short int), FRAME, m_pOutput);
   }
   fclose(m_pOutput);
   fclose(m_pInput);
}
void LowpassFilter(short int nIn[],short int nOut[],int nLen,short int h[])
{
   short int i,j;
   int sum;
   //缓冲区的内容更新
   for(i = 0;i < FRAME;i++)
   {
nBuff[i + nLen -1] = nIn[i];
   }
   //FIR滤波处理
   for(i = 0;i < FRAME;i++)
   {
       sum = 0;
       for(j = 0;j < nLen;j++)
       {
           sum += h[j] * nBuff[i - j + nLen -1];
       }
       nOut[i] = sum >> 15;
   }
   //更新缓冲区的内容
   for(i = 0;i < nLen - 1;i++)
   {
       nBuff[nLen - i - 2] = nIn[FRAME - i - 1];
   }
}