/***** 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 <stdlib.h>#include <stdio.h>#include "typedef.h"#include "basop.h"#include "cst_lbc.h"#include "lbccodec.h"#include "exc_lbc.h"#include "tame.h"#include "tab_lbc.h"#include "coder_pc.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);}