--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtwamr/lpc.c	Mon May 06 06:24:26 2024 +0000
@@ -0,0 +1,97 @@
+/*
+********************************************************************************
+*
+*      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             : lpc.c
+*
+********************************************************************************
+*/
+
+/*
+********************************************************************************
+*                         MODULE INCLUDE FILE AND VERSION ID
+********************************************************************************
+*/
+#include "namespace.h"
+#include "lpc.h"
+
+/*
+********************************************************************************
+*                         INCLUDE FILES
+********************************************************************************
+*/
+#include "tw_amr.h"
+#include "typedef.h"
+#include "basic_op.h"
+#include "oper_32b.h"
+#include "autocorr.h"
+#include "lag_wind.h"
+#include "levinson.h"
+#include "cnst.h"
+#include "no_count.h"
+#include "window.h"
+
+/*
+********************************************************************************
+*                         PUBLIC PROGRAM CODE
+********************************************************************************
+*/
+ 
+/*************************************************************************
+*
+*  Function:   lpc_reset
+*
+**************************************************************************
+*/
+void lpc_reset (lpcState *state)
+{
+  Levinson_reset(&state->levinsonSt);
+}
+
+int lpc(
+    lpcState *st,     /* i/o: State struct                */
+    enum Mode mode,   /* i  : coder mode                  */
+    Word16 x[],       /* i  : Input signal           Q15  */
+    Word16 x_12k2[],  /* i  : Input signal (EFR)     Q15  */
+    Word16 a[]        /* o  : predictor coefficients Q12  */
+)
+{
+   Word16 rc[4];                  /* First 4 reflection coefficients Q15 */
+   Word16 rLow[MP1], rHigh[MP1];  /* Autocorrelations low and hi      */
+                                  /* No fixed Q value but normalized  */
+                                  /* so that overflow is avoided      */
+   
+   test ();
+   if ( sub (mode, MR122) == 0)
+   {
+       /* Autocorrelations */
+       Autocorr(x_12k2, M, rHigh, rLow, window_160_80);              
+       /* Lag windowing    */
+       Lag_window(M, rHigh, rLow);                                   
+       /* Levinson Durbin  */
+       Levinson(&st->levinsonSt, rHigh, rLow, &a[MP1], rc);
+
+       /* Autocorrelations */
+       Autocorr(x_12k2, M, rHigh, rLow, window_232_8);                  
+       /* Lag windowing    */
+       Lag_window(M, rHigh, rLow);                                  
+       /* Levinson Durbin  */
+       Levinson(&st->levinsonSt, rHigh, rLow, &a[MP1 * 3], rc);
+   }
+   else
+   {
+       /* Autocorrelations */
+       Autocorr(x, M, rHigh, rLow, window_200_40);                 
+       /* Lag windowing    */
+       Lag_window(M, rHigh, rLow);                                   
+       /* Levinson Durbin  */
+       Levinson(&st->levinsonSt, rHigh, rLow, &a[MP1 * 3], rc);
+   }
+
+   return 0;
+}