+
−/*
+
−********************************************************************************
+
−*
+
−*      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             : dec_lag3.c
+
−*      Purpose          : Decoding of fractional pitch lag with 1/3 resolution.
+
−*                         Extract the integer and fraction parts of the pitch lag from
+
−*                         the received adaptive codebook index.
+
−*
+
−********************************************************************************
+
−*/
+
−
+
−/*
+
−********************************************************************************
+
−*                         MODULE INCLUDE FILE AND VERSION ID
+
−********************************************************************************
+
−*/
+
−#include "namespace.h"
+
−#include "dec_lag3.h"
+
− 
+
−/*
+
−********************************************************************************
+
−*                         INCLUDE FILES
+
−********************************************************************************
+
−*/
+
−#include "typedef.h"
+
−#include "basic_op.h"
+
−#include "no_count.h"
+
−
+
−/*
+
−********************************************************************************
+
−*                         LOCAL VARIABLES AND TABLES
+
−********************************************************************************
+
−*/
+
−
+
−/*
+
−********************************************************************************
+
−*                         PUBLIC PROGRAM CODE
+
−********************************************************************************
+
−*/
+
−/*************************************************************************
+
− *   FUNCTION:   Dec_lag3
+
− *
+
− *   PURPOSE:  Decoding of fractional pitch lag with 1/3 resolution.
+
− *             Extract the integer and fraction parts of the pitch lag from
+
− *             the received adaptive codebook index.
+
− *
+
− *    See "Enc_lag3.c" for more details about the encoding procedure.
+
− *
+
− *    The fractional lag in 1st and 3rd subframes is encoded with 8 bits
+
− *    while that in 2nd and 4th subframes is relatively encoded with 4, 5
+
− *    and 6 bits depending on the mode.
+
− *
+
− *************************************************************************/
+
−void Dec_lag3(Word16 index,     /* i : received pitch index                 */
+
−              Word16 t0_min,    /* i : minimum of search range              */
+
−              Word16 t0_max,    /* i : maximum of search range              */
+
−              Word16 i_subfr,   /* i : subframe flag                        */
+
−              Word16 T0_prev,   /* i : integer pitch delay of last subframe
+
−                                       used in 2nd and 4th subframes        */
+
−              Word16 * T0,      /* o : integer part of pitch lag            */ 
+
−              Word16 * T0_frac, /* o : fractional part of pitch lag         */
+
−              Word16 flag4      /* i : flag for encoding with 4 bits        */
+
−              )
+
−{
+
−    Word16 i;
+
−    Word16 tmp_lag;
+
−    
+
−    test (); 
+
−    if (i_subfr == 0) {    /* if 1st or 3rd subframe */
+
−       test ();
+
−	   if (sub(index, 197) < 0) {
+
−          
+
−          *T0 = add(mult(add(index, 2), 10923), 19);
+
−           
+
−          i = add(add(*T0, *T0), *T0);
+
−          *T0_frac = add(sub(index, i), 58);
+
−       } else {
+
−          *T0 = sub(index, 112);
+
−          *T0_frac = 0;                                        move16 ();
+
−       }
+
−       
+
−    } else {    /* 2nd or 4th subframe */
+
−
+
−       test ();
+
−       if (flag4 == 0) {
+
−          
+
−          /* 'normal' decoding: either with 5 or 6 bit resolution */
+
−          
+
−          i = sub(mult(add(index, 2), 10923), 1);
+
−          *T0 = add(i, t0_min);
+
−          
+
−          i = add(add(i, i), i);
+
−          *T0_frac = sub(sub(index, 2), i);
+
−       }
+
−       else {
+
−          
+
−          /* decoding with 4 bit resolution */
+
−          
+
−          tmp_lag = T0_prev;                                   move16 ();
+
−
+
−          test ();
+
−          if ( sub( sub(tmp_lag, t0_min), 5) > 0)
+
−             tmp_lag = add (t0_min, 5);
+
−          test ();
+
−          if ( sub( sub(t0_max, tmp_lag), 4) > 0)
+
−             tmp_lag = sub (t0_max, 4);
+
−          
+
−          test ();          
+
−          if (sub(index, 4) < 0)
+
−          {
+
−             i = sub(tmp_lag, 5);
+
−             *T0 = add(i, index);
+
−             *T0_frac = 0;                                     move16 ();
+
−          }
+
−          else
+
−          {
+
−             test ();
+
−             if (sub(index, 12) < 0)
+
−             {
+
−                i = sub(mult(sub(index, 5), 10923), 1);
+
−                *T0 = add(i, tmp_lag);
+
−                
+
−                i = add(add(i, i), i);
+
−                *T0_frac = sub(sub(index, 9), i);
+
−             }
+
−             else
+
−             {
+
−                i = add( sub (index, 12), tmp_lag);
+
−                *T0 = add (i, 1);                
+
−                *T0_frac = 0;                                  move16 ();
+
−             }
+
−          }
+
−          
+
−       } /* end if (decoding with 4 bit resolution) */
+
−    }
+
−    
+
−    return;
+
−}