extern void Autocorr(Word16 x[], Word16 m,Word16 r_h[], Word16 r_l[],  Word16 *exp_R0 );

extern void Lag_window(Word16 m,Word16 r_h[],Word16 r_l[]);

extern void Levinson(
  Word16 Rh[],      /* (i)     : Rh[M+1] Vector of autocorrelations (msb) */
  Word16 Rl[],      /* (i)     : Rl[M+1] Vector of autocorrelations (lsb) */
  Word16 A[],       /* (o) Q12 : A[M]    LPC coefficients  (m = 10)       */
  Word16 rc[],      /* (o) Q15 : rc[M]   Reflection coefficients.         */
  Word16 *Err       /* (o)     : Residual energy                          */
);