--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtwamr/ec_gains.c	Mon May 06 02:08:43 2024 +0000
@@ -0,0 +1,257 @@
+/*
+********************************************************************************
+*
+*      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             : ec_gains.c
+*      Purpose:         : Error concealment for pitch and codebook gains
+*
+********************************************************************************
+*/
+ 
+/*
+********************************************************************************
+*                         MODULE INCLUDE FILE AND VERSION ID
+********************************************************************************
+*/
+#include "namespace.h"
+#include "ec_gains.h"
+ 
+/*
+********************************************************************************
+*                         INCLUDE FILES
+********************************************************************************
+*/
+#include "typedef.h"
+#include "basic_op.h"
+#include "oper_32b.h"
+#include "no_count.h"
+#include "cnst.h"
+#include "gmed_n.h"
+#include "gc_pred.h"
+#include "gains_tab.h"
+
+/*
+********************************************************************************
+*                         PUBLIC PROGRAM CODE
+********************************************************************************
+*/
+
+/*
+**************************************************************************
+*
+*  Function    : ec_gain_code_reset
+*  Purpose     : Resets state memory
+*
+**************************************************************************
+*/
+void ec_gain_code_reset (ec_gain_codeState *state)
+{
+  Word16 i;
+  
+  for ( i = 0; i < 5; i++)
+      state->gbuf[i] = 1;
+  state->past_gain_code = 0;
+  state->prev_gc = 1;       
+}
+ 
+/*
+**************************************************************************
+*
+*  Function    : ec_gain_code
+*  Purpose     : conceal the codebook gain
+*                Call this function only in BFI (instead of normal gain
+*                decoding function)
+*
+**************************************************************************
+*/
+void ec_gain_code (
+    ec_gain_codeState *st,    /* i/o : State struct                     */
+    gc_predState *pred_state, /* i/o : MA predictor state               */
+    Word16 state,             /* i   : state of the state machine       */
+    Word16 *gain_code         /* o   : decoded innovation gain          */
+)
+{
+    static const Word16 cdown[7] =
+    {
+        32767, 32112, 32112, 32112,
+        32112, 32112, 22937
+    };
+
+    Word16 tmp;
+    Word16 qua_ener_MR122;
+    Word16 qua_ener;
+    
+    /* calculate median of last five gain values */
+    tmp = gmed_n (st->gbuf,5);                                 move16 ();
+
+    /* new gain = minimum(median, past_gain) * cdown[state] */
+    test (); 
+    if (sub (tmp, st->past_gain_code) > 0)
+    {
+        tmp = st->past_gain_code;                              move16 (); 
+    }
+    tmp = mult (tmp, cdown[state]);
+    *gain_code = tmp;                                          move16 (); 
+
+    /* update table of past quantized energies with average of
+     * current values
+     */
+    gc_pred_average_limited(pred_state, &qua_ener_MR122, &qua_ener);
+    gc_pred_update(pred_state, qua_ener_MR122, qua_ener);
+}
+
+/*
+**************************************************************************
+*
+*  Function    : ec_gain_code_update
+*  Purpose     : update the codebook gain concealment state;
+*                limit gain_code if the previous frame was bad
+*                Call this function always after decoding (or concealing)
+*                the gain
+*
+**************************************************************************
+*/
+void ec_gain_code_update (
+    ec_gain_codeState *st,    /* i/o : State struct                     */
+    Word16 bfi,               /* i   : flag: frame is bad               */
+    Word16 prev_bf,           /* i   : flag: previous frame was bad     */
+    Word16 *gain_code         /* i/o : decoded innovation gain          */
+)
+{
+    Word16 i;
+
+    /* limit gain_code by previous good gain if previous frame was bad */
+    test ();
+    if (bfi == 0)
+    {
+	test ();
+        if (prev_bf != 0)
+        {
+            test (); 
+            if (sub (*gain_code, st->prev_gc) > 0)
+            {
+                *gain_code = st->prev_gc;     move16 (); 
+            }
+        }
+        st->prev_gc = *gain_code;                          move16 (); 
+    }
+
+    /* update EC states: previous gain, gain buffer */
+    st->past_gain_code = *gain_code;                       move16 (); 
+    
+    for (i = 1; i < 5; i++)
+    {
+        st->gbuf[i - 1] = st->gbuf[i];                     move16 (); 
+    }
+    st->gbuf[4] = *gain_code;                              move16 (); 
+
+    return;
+}
+
+/*
+**************************************************************************
+*
+*  Function:   ec_gain_pitch_reset
+*  Purpose:    Resets state memory
+*
+**************************************************************************
+*/
+void ec_gain_pitch_reset (ec_gain_pitchState *state)
+{
+  Word16 i;
+  
+  for(i = 0; i < 5; i++)
+      state->pbuf[i] = 1640;
+  state->past_gain_pit = 0; 
+  state->prev_gp = 16384;   
+}
+ 
+/*
+**************************************************************************
+*
+*  Function    : ec_gain_pitch
+*  Purpose     : conceal the pitch gain
+*                Call this function only in BFI (instead of normal gain
+*                decoding function)
+*
+**************************************************************************
+*/
+void ec_gain_pitch (
+    ec_gain_pitchState *st, /* i/o : state variables                   */
+    Word16 state,           /* i   : state of the state machine        */
+    Word16 *gain_pitch      /* o   : pitch gain (Q14)                  */
+)
+{
+    static const Word16 pdown[7] =
+    {
+        32767, 32112, 32112, 26214,
+        9830, 6553, 6553
+    };
+
+    Word16 tmp;
+
+    /* calculate median of last five gains */
+    tmp = gmed_n (st->pbuf, 5);                        move16 (); 
+
+    /* new gain = minimum(median, past_gain) * pdown[state] */
+    test (); 
+    if (sub (tmp, st->past_gain_pit) > 0)
+    {
+        tmp = st->past_gain_pit;                       move16 (); 
+    }
+    *gain_pitch = mult (tmp, pdown[state]);
+}
+
+/*
+**************************************************************************
+*
+*  Function    : ec_gain_pitch_update
+*  Purpose     : update the pitch gain concealment state;
+*                limit gain_pitch if the previous frame was bad
+*                Call this function always after decoding (or concealing)
+*                the gain
+*
+**************************************************************************
+*/
+void ec_gain_pitch_update (
+    ec_gain_pitchState *st, /* i/o : state variables                   */
+    Word16 bfi,             /* i   : flag: frame is bad                */
+    Word16 prev_bf,         /* i   : flag: previous frame was bad      */
+    Word16 *gain_pitch      /* i/o : pitch gain                        */
+)
+{
+    Word16 i;
+
+    test (); 
+    if (bfi == 0)
+    {
+        test ();
+        if (prev_bf != 0)
+        {
+            test (); 
+            if (sub (*gain_pitch, st->prev_gp) > 0)
+            {
+                *gain_pitch = st->prev_gp;
+            }
+        }
+        st->prev_gp = *gain_pitch;                         move16 (); 
+    }
+    
+    st->past_gain_pit = *gain_pitch;                       move16 ();
+
+    test (); 
+    if (sub (st->past_gain_pit, 16384) > 0)  /* if (st->past_gain_pit > 1.0) */
+    {
+        st->past_gain_pit = 16384;                         move16 (); 
+    }
+    for (i = 1; i < 5; i++)
+    {
+        st->pbuf[i - 1] = st->pbuf[i];                     move16 (); 
+    }
+    st->pbuf[4] = st->past_gain_pit;                       move16 (); 
+}