--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtwamr/levinson.h	Mon May 06 06:01:56 2024 +0000
@@ -0,0 +1,62 @@
+/*
+********************************************************************************
+*
+*      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             : levinson.h
+*      Purpose          : Levinson-Durbin algorithm in double precision.
+*                       : To compute the LP filter parameters from the
+*                       : speech autocorrelations.
+*
+********************************************************************************
+*/
+#ifndef levinson_h
+#define levinson_h "$Id $"
+ 
+/*
+********************************************************************************
+*                         INCLUDE FILES
+********************************************************************************
+*/
+#include "typedef.h"
+#include "cnst.h"
+ 
+/*
+********************************************************************************
+*                         LOCAL VARIABLES AND TABLES
+********************************************************************************
+*/
+ 
+/*
+********************************************************************************
+*                         DEFINITION OF DATA TYPES
+********************************************************************************
+*/
+typedef struct {
+  Word16 old_A[M + 1];     /* Last A(z) for case of unstable filter */
+} LevinsonState;
+ 
+/*
+********************************************************************************
+*                         DECLARATION OF PROTOTYPES
+********************************************************************************
+*/
+ 
+void Levinson_reset (LevinsonState *st);
+/* reset of pre processing state (i.e. set state memory to zero)
+   returns 0 on success
+ */
+
+int Levinson (
+    LevinsonState *st,
+    Word16 Rh[],       /* i : Rh[m+1] Vector of autocorrelations (msb) */
+    Word16 Rl[],       /* i : Rl[m+1] Vector of autocorrelations (lsb) */
+    Word16 A[],        /* o : A[m]    LPC coefficients  (m = 10)       */
+    Word16 rc[]        /* o : rc[4]   First 4 reflection coefficients  */
+);
+ 
+#endif