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fir.c
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Upload Date: 2017-06-07
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Visual C++ Books

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C/C++

fir.c：Code Content
  1. #include <stdio.h>
  3. #define length 256
  5. int input[length],output[length];
  7. static int filter(int xin[],int xout[],int n, int h[]);
  9. static void dataIO(void);
  11. static int h[37]={ -78,-152,-210,-173,18,355,737,983,903,413,-374,
  12. -1139,-1443,-910,582,2792,5154,6963,7640,6963,5154,2792,582,-910,
  13. -1443,-1139,-374,413,903,983,737,355,18,-173,-210,-152,-78};
  14. /*Q15*/
  16. static int x1[length+37];
  17. /*低通滤波定点子程序*/
  19. static int filter(int indata[],int outdata[],int n,int h[])
  20. {
  21. int i,j;
  22. long sum;
  24. for(i=0;i<length;i++) x1[n+i-1]=indata[i];
  26. for(i=0;i<(n-1);i++) x1[n-i-2]=indata[length-i-1];
  28. for(i=0;i<length;i++)
  29. {
  30. sum=0;
  31. for(j=0;j<n;j++) sum+=(long)h[j]*x1[i-j+n-1];
  32. outdata[i]=sum>>15;
  33. }
  34. return 1;
  35. }
  36. void main()
  37. { 
  38.    while(1)
  39.    {
  40. dataIO();
  41. filter(input,output,19,h);
  42.    }
  43. }
  44. static void dataIO()
  45. {
  46. /*do data I/O*/
  47. return;
  48. }