+
−/*
+
−********************************************************************************
+
−*
+
−*      GSM AMR-NB speech codec   R98   Version 7.6.0   December 12, 2001
+
−*                                R99   Version 3.3.0                
+
−*                                REL-4 Version 4.1.0                
+
−*
+
−********************************************************************************
+
−*
+
−*      File             : autocorr.h
+
−*      Purpose          : Compute autocorrelations of signal with windowing
+
−*
+
−********************************************************************************
+
−*/
+
−#ifndef autocorr_h
+
−#define autocorr_h "$Id $"
+
− 
+
−/*
+
−********************************************************************************
+
−*                         INCLUDE FILES
+
−********************************************************************************
+
−*/
+
−#include "typedef.h"
+
− 
+
−/*
+
−********************************************************************************
+
−*                         DEFINITION OF DATA TYPES
+
−********************************************************************************
+
−*/
+
− 
+
−/*
+
−********************************************************************************
+
−*                         DECLARATION OF PROTOTYPES
+
−********************************************************************************
+
−*/
+
−/*
+
−**************************************************************************
+
−*
+
−*  Function    : autocorr
+
−*  Purpose     : Compute autocorrelations of signal with windowing
+
−*  Description : - Windowing of input speech:   s'[n] = s[n] * w[n]
+
−*                - Autocorrelations of input speech:
+
−*                  r[k] = sum_{i=k}^{239} s'[i]*s'[i-k]    k=0,...,10
+
−*                The autocorrelations are expressed in normalized 
+
−*                double precision format.
+
−*  Returns     : Autocorrelation
+
−*
+
−**************************************************************************
+
−*/
+
−Word16 Autocorr (
+
−    Word16 x[],        /* (i)    : Input signal (L_WINDOW)             */
+
−    Word16 m,          /* (i)    : LPC order                           */
+
−    Word16 r_h[],      /* (o)    : Autocorrelations  (msb)  (MP1)      */
+
−    Word16 r_l[],      /* (o)    : Autocorrelations  (lsb)  (MP1)      */
+
−    const Word16 wind[]/* (i)    : window for LPC analysis. (L_WINDOW) */
+
−);
+
− 
+
−#endif