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/* 
** 
** File:    tame.c 
** 
** Description: Functions used to avoid possible explosion of the decoder 
**              excitation in case of series of long term unstable filters 
**              and when the encoder and the decoder are de-synchronized 
** 
** Functions: 
** 
**  Computing excitation error estimation : 
**      Update_Err() 
**  Test excitation error : 
**      Test_Err() 
*/ 
 
/* 
    ITU-T G.723 Speech Coder   ANSI-C Source Code     Version 5.0 
    copyright (c) 1995, AudioCodes, DSP Group, France Telecom, 
    Universite de Sherbrooke.  All rights reserved. 
*/ 
#include  
#include  
 
#include "typedef.h" 
#include "basop.h" 
#include "cst_lbc.h" 
#include "lbccodec.h" 
#include "coder.h" 
#include "exc_lbc.h" 
#include "tame.h" 
#include "tab_lbc.h" 
 
 
/* 
** 
** Function:        Update_Err() 
** 
** Description:     Estimation of the excitation error associated 
**                  to the excitation signal when it is disturbed at 
**                  the decoder, the disturbing signal being filtered 
**                  by the long term synthesis filters 
**                  one value for (SubFrLen/2) samples 
**                  Updates the table CodStat.Err 
** 
** Links to text:   Section 
** 
** Arguments: 
** 
**  Word16 Olp      Center value for pitch delay 
**  Word16 AcLg     Offset value for pitch delay 
**  Word16 AcGn     Index of Gain LT filter 
** 
** Outputs: None 
** 
** Return value:    None 
** 
*/ 
 
void Update_Err( 
    Word16 Olp, Word16 AcLg, Word16 AcGn 
) 
{ 
    Word16 *ptr_tab; 
    Word16 i, iz, temp1, temp2; 
    Word16 Lag; 
    Word32 Worst1, Worst0, L_temp; 
    Word16 beta; 
 
    Lag = Olp - (Word16)Pstep + AcLg; 
 
    /* Select Quantization tables */ 
    i = 0 ; 
    ptr_tab = tabgain85; 
    if ( WrkRate == Rate63 ) { 
        if ( Olp >= (Word16) (SubFrLen-2) ) ptr_tab = tabgain170; 
    } 
    else { 
        ptr_tab = tabgain170; 
    } 
    beta = ptr_tab[(int)AcGn]; /* beta = gain * 8192 */ 
 
 
    if(Lag <= (SubFrLen/2)) { 
        Worst0 = L_mls(CodStat.Err[0], beta); 
        Worst0 = L_shl(Worst0, 2); 
        Worst0 = L_add(Err0, Worst0); 
        Worst1 = Worst0; 
    } 
 
    else { 
        iz = mult(Lag, 1092);   /* Lag / 30 */ 
        temp1 = add(iz, 1); 
        temp2 = sub(shl(temp1, 5), shl(temp1, 1));      /* 30 (iz+1) */ 
        if(temp2 != Lag) { 
 
            if(iz == 1) { 
                Worst0 = L_mls(CodStat.Err[0], beta); 
                Worst0 = L_shl(Worst0, 2); 
                Worst0 = L_add(Err0, Worst0); 
                Worst1 = L_mls(CodStat.Err[1], beta); 
                Worst1 = L_shl(Worst1, 2); 
                Worst1 = L_add(Err0, Worst1); 
                if(Worst0 > Worst1) Worst1 = Worst0; 
                else Worst0 = Worst1; 
            } 
 
            else { 
                Worst0 = L_mls(CodStat.Err[iz-2], beta); 
                Worst0 = L_shl(Worst0, 2); 
                Worst0 = L_add(Err0, Worst0); 
                L_temp = L_mls(CodStat.Err[iz-1], beta); 
                L_temp = L_shl(L_temp, 2); 
                L_temp = L_add(Err0, L_temp); 
                if(L_temp > Worst0) Worst0 = L_temp; 
                Worst1 = L_mls(CodStat.Err[iz], beta); 
                Worst1 = L_shl(Worst1, 2); 
                Worst1 = L_add(Err0, Worst1); 
                if(L_temp > Worst1) Worst1 = L_temp; 
            } 
        } 
        else {  /* Lag % SubFrLen = 0 */ 
            Worst0 = L_mls(CodStat.Err[iz-1], beta); 
            Worst0 = L_shl(Worst0, 2); 
            Worst0 = L_add(Err0, Worst0); 
            Worst1 = L_mls(CodStat.Err[iz], beta); 
            Worst1 = L_shl(Worst1, 2); 
            Worst1 = L_add(Err0, Worst1); 
        } 
    } 
 
    for(i=4; i>=2; i--) { 
        CodStat.Err[i] = CodStat.Err[i-2]; 
    } 
    CodStat.Err[0] = Worst0; 
    CodStat.Err[1] = Worst1; 
 
    return; 
} 
 
/* 
** 
** Function:        Test_Err() 
** 
** Description:     Check the error excitation maximum for 
**                  the subframe and computes an index iTest used to 
**                  calculate the maximum nb of filters (in Find_Acbk) : 
**                  Bound = Min(Nmin + iTest x pas, Nmax) , with 
**                  AcbkGainTable085 : pas = 2, Nmin = 51, Nmax = 85 
**                  AcbkGainTable170 : pas = 4, Nmin = 93, Nmax = 170 
**                  iTest depends on the relative difference between 
**                  errmax and a fixed threshold 
** 
** Links to text:   Section 
** 
** Arguments: 
** 
**  Word16 Lag1      1st long term Lag of the tested zone 
**  Word16 Lag2      2nd long term Lag of the tested zone 
** 
** Outputs: None 
** 
** Return value: 
**  Word16          index iTest used to compute Acbk number of filters 
*/ 
 
Word16 Test_Err( 
    Word16 Lag1, Word16 Lag2 
) 
{ 
 
    int i, i1, i2; 
    Word16 zone1, zone2; 
    Word32 Acc, Err_max; 
    Word16 iTest; 
 
    i2 = Lag2 + ClPitchOrd/2; 
    zone2 = mult( (Word16) i2, (Word16) 1092); 
 
    i1 = - SubFrLen + 1 + Lag1 - ClPitchOrd/2; 
    if(i1 <= 0) i1 = 1; 
    zone1 = mult( (Word16) i1, (Word16) 1092); 
 
    Err_max = -1L; 
    for(i=zone2; i>=zone1; i--) { 
        Acc = L_sub(CodStat.Err[i], Err_max); 
        if(Acc > 0L) { 
                Err_max = CodStat.Err[i]; 
        } 
    } 
    Acc = L_sub(Err_max, ThreshErr); 
    if((Acc > 0L) || (CodStat.SinDet < 0 ) ) { 
        iTest = 0; 
    } 
    else { 
        Acc = L_negate(Acc); 
        Acc = L_shr(Acc, DEC); 
        iTest = extract_l(Acc); 
    } 
 
    return(iTest); 
}