shithub: sox

ref: c78ac707b07a3c8dea4685274cb6f1b3ba1ea93f
dir: /amr-wb/weight_a.c/

/*-------------------------------------------------------------------*
 *                         WB_VAD.C                                  *
 *-------------------------------------------------------------------*
 * Weighting of LPC coefficients.                                    *
 *   ap[i]  =  a[i] * (gamma ** i)                                   *
 *-------------------------------------------------------------------*/

#include "typedef.h"
#include "basic_op.h"
#include "count.h"

void Weight_a(
     Word16 a[],                           /* (i) Q12 : a[m+1]  LPC coefficients             */
     Word16 ap[],                          /* (o) Q12 : Spectral expanded LPC coefficients   */
     Word16 gamma,                         /* (i) Q15 : Spectral expansion factor.           */
     Word16 m                              /* (i)     : LPC order.                           */
)
{
    Word16 i, fac;

    ap[0] = a[0];                          move16();
    fac = gamma;                           move16();
    for (i = 1; i < m; i++)
    {
        ap[i] = round(L_mult(a[i], fac));  move16();
        fac = round(L_mult(fac, gamma));
    }
    ap[m] = round(L_mult(a[m], fac));      move16();

    return;
}