www.pudn.com > lpc.zip > hp100_i.c

/**********************************************************************
*
*      HP100 Version 55
*
**********************************************************************
*
*    100 Hz High Pass Filter
*
* Jan 92 - corrected typo (1.937148 to 1.935715),
*          rounded coefficients to 7 places,
*          corrected and merged gain (.97466**4),
*          merged numerator into first two sections.
*/

#include "lpcdefs.h"
#include "ourstuff.h"

hp100_i(speech)
int_type speech[];
{
  int_type i;
  int_type si, err;
  int_type z11=0, z21=0, z12=0, z22=0;

  for( i = 0;i>14));*/
    err = si + ((952*z11) >> 9) - ((443*z21) >> 9);
    si = err - ((1024*z11) >> 9) + z21;
    z21 = z11;
    z11 = err;
    
    err = si + ((991*z12) >> 9) - ((482*z22) >> 9);
    si = err - ((1024*z12) >> 9) + z22;
    z22 = z12;
    z12 = err;

    speech[i] = ((462*si) >> 9);
  }
}