--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/agc_amr.c	Wed Apr 03 05:47:51 2024 +0000
@@ -0,0 +1,244 @@
+/*
+*****************************************************************************
+*
+*      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
+*****************************************************************************
+*/
+#if 0
+#include "agc.h"
+const char agc_id[] = "@(#)$Id $" agc_h;
+#endif
+
+/*
+*****************************************************************************
+*                         INCLUDE FILES
+*****************************************************************************
+*/
+#include <stdlib.h>
+#include <stdio.h>
+#include "typedef.h"
+#include "basic_op.h"
+#include "count.h"
+#include "sig_proc.h"
+#include "cnst.h"
+ 
+Word16 past_gain;               /* initial value of past_gain = 1.0  */
+
+/*
+*****************************************************************************
+*                         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
+*  Purpose     : Scales the postfilter output on a subframe basis
+*
+**************************************************************************
+*/
+void agc (
+    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)
+    {
+        past_gain = 0;          move16 (); 
+        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 = (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 = 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 (); 
+    }
+
+    past_gain = gain;           move16 (); 
+}
+
+/*
+**************************************************************************
+*
+*  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;
+}