--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtwamr/dtx_dec.h	Tue May 07 00:05:12 2024 +0000
@@ -0,0 +1,133 @@
+/*
+*****************************************************************************
+*
+*      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             : dtx_dec.h
+*      Purpose          : Decode comfort noice when in DTX
+*
+*****************************************************************************
+*/
+#ifndef dtx_dec_h
+#define dtx_dec_h "$Id $" 
+ 
+/*
+*****************************************************************************
+*                         INCLUDE FILES
+*****************************************************************************
+*/
+#include "tw_amr.h"
+#include "typedef.h"
+#include "dtx_common.h"
+#include "d_plsf.h"
+#include "gc_pred.h"
+#include "c_g_aver.h"
+
+/*
+*****************************************************************************
+*                         LOCAL VARIABLES AND TABLES
+*****************************************************************************
+*/
+enum DTXStateType {SPEECH = 0, DTX, DTX_MUTE};
+
+#define DTX_MAX_EMPTY_THRESH 50
+
+/*
+*****************************************************************************
+*                         DEFINITION OF DATA TYPES
+*****************************************************************************
+*/
+
+typedef struct {
+   Word16 since_last_sid;
+   Word16 true_sid_period_inv;
+   Word16 log_en;
+   Word16 old_log_en;
+   Word32 L_pn_seed_rx; 
+   Word16 lsp[M];
+   Word16 lsp_old[M]; 
+   
+   Word16 lsf_hist[M*DTX_HIST_SIZE];
+   Word16 lsf_hist_ptr;
+   Word16 lsf_hist_mean[M*DTX_HIST_SIZE]; 
+   Word16 log_pg_mean;
+   Word16 log_en_hist[DTX_HIST_SIZE];
+   Word16 log_en_hist_ptr;
+
+   Word16 log_en_adjust;
+
+   Word16 dtxHangoverCount;
+   Word16 decAnaElapsedCount;
+
+   Word16 sid_frame;       
+   Word16 valid_data;          
+   Word16 dtxHangoverAdded;
+ 
+   enum DTXStateType dtxGlobalState;     /* contains previous state */
+                                         /* updated in main decoder */ 
+
+   Word16 data_updated;      /* marker to know if CNI data is ever renewed */ 
+
+} dtx_decState;
+
+/*
+*****************************************************************************
+*                         DECLARATION OF PROTOTYPES
+*****************************************************************************
+*/
+ 
+/*
+**************************************************************************
+*
+*  Function    : dtx_dec_reset
+*  Purpose     : Resets state memory
+*  Returns     : 0 on success
+*
+**************************************************************************
+*/
+void dtx_dec_reset (dtx_decState *st);
+ 
+/*
+**************************************************************************
+*
+*  Function    : dtx_dec
+*  Purpose     :
+*  Description :
+*                
+**************************************************************************
+*/
+int dtx_dec(
+   dtx_decState *st,                /* i/o : State struct                    */
+   Word16 mem_syn[],                /* i/o : AMR decoder state               */
+   D_plsfState* lsfState,           /* i/o : decoder lsf states              */
+   gc_predState* predState,         /* i/o : prediction states               */
+   Cb_gain_averageState* averState, /* i/o : CB gain average states          */
+   enum DTXStateType new_state,     /* i   : new DTX state                   */    
+   enum Mode mode,                  /* i   : AMR mode                        */
+   Word16 parm[],                   /* i   : Vector of synthesis parameters  */
+   Word16 synth[],                  /* o   : synthesised speech              */
+   Word16 A_t[]                     /* o   : decoded LP filter in 4 subframes*/
+   );
+
+void dtx_dec_activity_update(dtx_decState *st,
+                             Word16 lsf[],
+                             Word16 frame[]);
+
+/*
+**************************************************************************
+*
+*  Function    : rx_dtx_handler 
+*  Purpose     : reads the frame type and checks history  
+*  Description : to decide what kind of DTX/CNI action to perform
+
+**************************************************************************
+*/
+enum DTXStateType rx_dtx_handler(dtx_decState *st,           /* i/o : State struct */
+                                 enum RXFrameType frame_type /* i   : Frame type   */
+                                 );
+
+#endif