fir_filter.c

DSP 5416 有限冲击响应滤波器（ FIR ）算法

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/*  Copyright 2006 by SEED Electronic Technology LTD.                         */
/*  All rights reserved. SEED Electronic Technology LTD.                      */
/*  Restricted rights to use, duplicate or disclose this code are             */
/*  granted through contract.                                                 */
/******************************************************************************/


/******************************************************************************/
/*  Tiltle:FIR_filter.c                                                       */
/*  Platform:TMS320C5416                                                      */
/*  Author:[e-mail]                                                 */
/*  Purpose:FIR filter procedure for processing a group of data               */
/*  Prototype in C:void fir_filter(const short x[],const short h[],\          */
/*                                 short y[],int n,int m,int s);              */
/*  const short x[]：输入信号的缓冲数组，short类型，在滤波中不可修改          */
/*  const short h[]：滤波器的系数数组，short类型，在滤波中不可修改            */
/*  short y[]：输出信号的缓冲数组，short类型                                  */
/*  n：滤波器长度，本例中为ORDER_FIR                                          */
/*  m：输入信号的长度，即数组x[]的长度                                        */
/*  s：生成整型的滤波器系数时使用的移位数目，本例中为ROUND_FIR                */
/*  Note:-o3 compile option recommended.                                      */
/*       x[] and y[] not permitted to have relative addresses.                */
/*       filter length supposed to be larger than 16.                         */
/*       input length supposed to be larger than 16                           */
/*       only first m-n point output legal                                    */
/*  Version:1.0   Dec25,2006   [e-mail]                             */
/*  Rivision:                                                                 */
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void fir_filter(const short x[],const short h[],short y[],int n,int m,int s)
{
  int i,j;
  long y0;
  long acc;

   _nassert(m>=16);
   _nassert(n>=16);
   
   
   for(j=0;j<m;j++)
    {
     acc=0;
     
     for(i=0;i<n;i++)
     {
      if(i+j>=m) 
          break;
      else
         {
         y0=(long)x[i+j]*(long)h[i];
         acc=acc+y0;
         }
     }
     
     *y++=(short)(acc>>s);
    
    
    }
}


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