+
−/*
+
−*****************************************************************************
+
−*
+
−*      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             : agc.c
+
−*
+
−*****************************************************************************
+
−*/
+
−
+
−/*
+
−*****************************************************************************
+
−*                         MODULE INCLUDE FILE AND VERSION ID
+
−*****************************************************************************
+
−*/
+
−#include "namespace.h"
+
−#include "agc.h"
+
−
+
−/*
+
−*****************************************************************************
+
−*                         INCLUDE FILES
+
−*****************************************************************************
+
−*/
+
−#include "typedef.h"
+
−#include "basic_op.h"
+
−#include "no_count.h"
+
−#include "cnst.h"
+
−#include "inv_sqrt.h"
+
− 
+
−/*
+
−*****************************************************************************
+
−*                         LOCAL VARIABLES AND TABLES
+
−*****************************************************************************
+
−*/
+
−
+
−/*
+
−*****************************************************************************
+
−*                         LOCAL PROGRAM CODE
+
−*****************************************************************************
+
−*/
+
−
+
−static Word32 energy_old( /* o : return energy of signal     */
+
−    Word16 in[],          /* i : input signal (length l_trm) */
+
−    Word16 l_trm          /* i : signal length               */
+
−)
+
−{
+
−    Word32 s;
+
−    Word16 i, temp;
+
−
+
−    temp = shr (in[0], 2);
+
−    s = L_mult (temp, temp);
+
−    
+
−    for (i = 1; i < l_trm; i++)
+
−    {
+
−        temp = shr (in[i], 2);
+
−        s = L_mac (s, temp, temp);
+
−    }
+
−
+
−    return s;
+
−}
+
−
+
−static Word32 energy_new( /* o : return energy of signal     */
+
−    Word16 in[],          /* i : input signal (length l_trm) */
+
−    Word16 l_trm          /* i : signal length               */
+
−)
+
−{
+
−    Word32 s;
+
−    Word16 i;
+
−    Flag ov_save;
+
−
+
−    ov_save = Overflow; move16 (); /* save overflow flag in case energy_old */
+
−                                   /* must be called                        */
+
−    s = L_mult(in[0], in[0]);
+
−    for (i = 1; i < l_trm; i++)
+
−    {
+
−        s = L_mac(s, in[i], in[i]);
+
−    }
+
−    
+
−    /* check for overflow */
+
−    test (); 
+
−    if (L_sub (s, MAX_32) == 0L)
+
−    {
+
−        Overflow = ov_save; move16 (); /* restore overflow flag */
+
−        s = energy_old (in, l_trm); move32 (); /* function result */
+
−    }
+
−    else
+
−    {
+
−       s = L_shr(s, 4);
+
−    }
+
−
+
−    return s;
+
−}
+
−/*
+
−*****************************************************************************
+
−*                         PUBLIC PROGRAM CODE
+
−*****************************************************************************
+
−*/
+
−/*
+
−**************************************************************************
+
−*
+
−*  Function    : agc_reset
+
−*  Purpose     : Reset of agc (i.e. set state memory to 1.0)
+
−*
+
−**************************************************************************
+
−*/
+
−void agc_reset (agcState *state)
+
−{
+
−  state->past_gain = 4096;   /* initial value of past_gain = 1.0  */
+
−}
+
− 
+
−/*
+
−**************************************************************************
+
−*
+
−*  Function    : agc
+
−*  Purpose     : Scales the postfilter output on a subframe basis
+
−*
+
−**************************************************************************
+
−*/
+
−int agc (
+
−    agcState *st,      /* i/o : agc state                        */
+
−    Word16 *sig_in,    /* i   : postfilter input signal  (l_trm) */
+
−    Word16 *sig_out,   /* i/o : postfilter output signal (l_trm) */
+
−    Word16 agc_fac,    /* i   : AGC factor                       */
+
−    Word16 l_trm       /* i   : subframe size                    */
+
−)
+
−{
+
−    Word16 i, exp;
+
−    Word16 gain_in, gain_out, g0, gain;
+
−    Word32 s;
+
−            
+
−    /* calculate gain_out with exponent */
+
−    s = energy_new(sig_out, l_trm); move32 (); /* function result */
+
−        
+
−    test (); 
+
−    if (s == 0)
+
−    {
+
−        st->past_gain = 0;          move16 (); 
+
−        return 0;
+
−    }
+
−    exp = sub (norm_l (s), 1);
+
−    gain_out = round (L_shl (s, exp));
+
−
+
−    /* calculate gain_in with exponent */
+
−    s = energy_new(sig_in, l_trm);   move32 (); /* function result */
+
−    
+
−    test (); 
+
−    if (s == 0)
+
−    {
+
−        g0 = 0;                 move16 (); 
+
−    }
+
−    else
+
−    {
+
−        i = norm_l (s);
+
−        gain_in = round (L_shl (s, i));
+
−        exp = sub (exp, i);
+
−
+
−        /*---------------------------------------------------*
+
−         *  g0 = (1-agc_fac) * sqrt(gain_in/gain_out);       *
+
−         *---------------------------------------------------*/
+
−
+
−        s = L_deposit_l (div_s (gain_out, gain_in));
+
−        s = L_shl (s, 7);       /* s = gain_out / gain_in */
+
−        s = L_shr (s, exp);     /* add exponent */
+
−
+
−        s = Inv_sqrt (s); move32 (); /* function result */
+
−        i = round (L_shl (s, 9));
+
−
+
−        /* g0 = i * (1-agc_fac) */
+
−        g0 = mult (i, sub (32767, agc_fac));
+
−    }
+
−
+
−    /* compute gain[n] = agc_fac * gain[n-1]
+
−                        + (1-agc_fac) * sqrt(gain_in/gain_out) */
+
−    /* sig_out[n] = gain[n] * sig_out[n]                        */
+
−
+
−    gain = st->past_gain;           move16 (); 
+
−
+
−    for (i = 0; i < l_trm; i++)
+
−    {
+
−        gain = mult (gain, agc_fac);
+
−        gain = add (gain, g0);
+
−        sig_out[i] = extract_h (L_shl (L_mult (sig_out[i], gain), 3));
+
−                                move16 (); 
+
−    }
+
−
+
−    st->past_gain = gain;           move16 (); 
+
−
+
−    return 0;
+
−}
+
−
+
−/*
+
−**************************************************************************
+
−*
+
−*  Function    : agc2
+
−*  Purpose     : Scales the excitation on a subframe basis
+
−*
+
−**************************************************************************
+
−*/
+
−void agc2 (
+
− Word16 *sig_in,        /* i   : postfilter input signal  */
+
− Word16 *sig_out,       /* i/o : postfilter output signal */
+
− Word16 l_trm           /* i   : subframe size            */
+
−)
+
−{
+
−    Word16 i, exp;
+
−    Word16 gain_in, gain_out, g0;
+
−    Word32 s;
+
−    
+
−    /* calculate gain_out with exponent */
+
−    s = energy_new(sig_out, l_trm);   move32 (); /* function result */
+
−        
+
−    test (); 
+
−    if (s == 0)
+
−    {
+
−        return;
+
−    }
+
−    exp = sub (norm_l (s), 1);
+
−    gain_out = round (L_shl (s, exp));
+
−
+
−    /* calculate gain_in with exponent */
+
−    s = energy_new(sig_in, l_trm);   move32 (); /* function result */
+
−    
+
−    test (); 
+
−    if (s == 0)
+
−    {
+
−        g0 = 0;                 move16 (); 
+
−    }
+
−    else
+
−    {
+
−        i = norm_l (s);
+
−        gain_in = round (L_shl (s, i));
+
−        exp = sub (exp, i);
+
−
+
−        /*---------------------------------------------------*
+
−         *  g0 = sqrt(gain_in/gain_out);                     *
+
−         *---------------------------------------------------*/
+
−
+
−        s = L_deposit_l (div_s (gain_out, gain_in));
+
−        s = L_shl (s, 7);       /* s = gain_out / gain_in */
+
−        s = L_shr (s, exp);     /* add exponent */
+
−
+
−        s = Inv_sqrt (s); move32 (); /* function result */
+
−        g0 = round (L_shl (s, 9));
+
−    }
+
−
+
−    /* sig_out(n) = gain(n) sig_out(n) */
+
−
+
−    for (i = 0; i < l_trm; i++)
+
−    {
+
−        sig_out[i] = extract_h (L_shl (L_mult (sig_out[i], g0), 3));
+
−                                move16 (); 
+
−    }
+
−
+
−    return;
+
−}