www.pudn.com > 200411301125332697.rar > qsidgain.c

/* 
   ITU-T G.729 Annex B     ANSI-C Source Code 
   Version 1.3    Last modified: August 1997 
 
   Copyright (c) 1996, France Telecom, Rockwell International, 
                       Universite de Sherbrooke. 
   All rights reserved. 
*/ 
 
/* Quantize SID gain                                      */ 
 
#include  
#include  
#include "typedef.h" 
#include "basic_op.h" 
#include "oper_32b.h" 
#include "ld8k.h" 
#include "vad.h" 
#include "dtx.h" 
#include "sid.h" 
#include "tab_dtx.h" 
 
/* Local function */ 
static Word16 Quant_Energy( 
  Word32 L_x,    /* (i)  : Energy                 */ 
  Word16 sh,     /* (i)  : Exponent of the energy */ 
  Word16 *enerq  /* (o)  : quantized energy in dB */ 
); 
 
/*-------------------------------------------------------------------* 
 * Function  Qua_Sidgain                                             * 
 *           ~~~~~~~~~~~                                             * 
 *-------------------------------------------------------------------*/ 
void Qua_Sidgain( 
  Word16 *ener,     /* (i)   array of energies                   */ 
  Word16 *sh_ener,  /* (i)   corresponding scaling factors       */ 
  Word16 nb_ener,   /* (i)   number of energies or               */ 
  Word16 *enerq,    /* (o)   decoded energies in dB              */ 
  Word16 *idx       /* (o)   SID gain quantization index         */ 
) 
{ 
  Word16 i; 
  Word32 L_x; 
  Word16 sh1, temp; 
  Word16 hi, lo; 
  Word32 L_acc; 
   
  if(nb_ener == 0) { 
    /* Quantize energy saved for frame erasure case                */ 
    /* L_x = average_ener                                          */ 
    L_acc = L_deposit_l(*ener); 
    L_acc = L_shl(L_acc, *sh_ener); /* >> if *sh_ener < 0 */ 
    L_Extract(L_acc, &hi, &lo); 
    L_x = Mpy_32_16(hi, lo, fact[0]); 
    sh1 = 0; 
  } 
  else { 
     
    /* 
     * Compute weighted average of energies 
     * ener[i] = enerR[i] x 2**sh_ener[i] 
     * L_x = k[nb_ener] x SUM(i=0->nb_ener-1) enerR[i] 
     * with k[nb_ener] =  fact_ener / nb_ener x L_FRAME x nbAcf 
     */ 
    sh1 = sh_ener[0]; 
    for(i=1; i -8dB */ 
  if(temp <= 0) { 
    *enerq = -12; 
    return(0); 
  } 
 
  temp = sub(e_tmp, 22111);      /* 22111 -> 65 dB */   
  if(temp > 0) { 
    *enerq = 66; 
    return(31); 
  } 
 
  temp = sub(e_tmp, 4762);       /* 4762 -> 14 dB */ 
  if(temp <= 0){ 
    e_tmp = add(e_tmp, 3401); 
    index = mult(e_tmp, 24); 
    if (index < 1) index = 1; 
    *enerq = sub(shl(index, 2), 8); 
    return(index); 
  } 
 
  e_tmp = sub(e_tmp, 340); 
  index = sub(shr(mult(e_tmp, 193), 2), 1); 
  if (index < 6) index = 6; 
  *enerq = add(shl(index, 1), 4); 
  return(index); 
}