/*
*****************************************************************************
*
*      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;
}