syntFilter.h File Reference

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Functions
void	syntFilter (float *Out, float *a, int len, float *mem)

Function Documentation

syntFilter()

void syntFilter	(	float *	Out,
		float *	a,
		int	len,
		float *	mem
	)

Definition at line 19 of file syntFilter.c.

References len(), and LPC_FILTERORDER.

Referenced by iLBC_decode().

    {
       int i, j;
       float *po, *pi, *pa, *pm;

       po=Out;

       /* Filter first part using memory from past */

       for (i=0; i<LPC_FILTERORDER; i++) {
           pi=&Out[i-1];
           pa=&a[1];
           pm=&mem[LPC_FILTERORDER-1];
           for (j=1; j<=i; j++) {
               *po-=(*pa++)*(*pi--);
           }
           for (j=i+1; j<LPC_FILTERORDER+1; j++) {
               *po-=(*pa++)*(*pm--);
           }
           po++;
       }

       /* Filter last part where the state is entirely in
          the output vector */

       for (i=LPC_FILTERORDER; i<len; i++) {
           pi=&Out[i-1];
           pa=&a[1];
           for (j=1; j<LPC_FILTERORDER+1; j++) {
               *po-=(*pa++)*(*pi--);
           }
           po++;
       }

       /* Update state vector */

       memcpy(mem, &Out[len-LPC_FILTERORDER],
           LPC_FILTERORDER*sizeof(float));
   }