--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtwamr/lsfwt.c	Mon May 06 03:38:26 2024 +0000
@@ -0,0 +1,104 @@
+/*
+********************************************************************************
+*
+*      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             : lsfwt.c
+*      Purpose          : Compute LSF weighting factors
+*
+********************************************************************************
+*/
+ 
+/*
+********************************************************************************
+*                         MODULE INCLUDE FILE AND VERSION ID
+********************************************************************************
+*/
+#include "namespace.h"
+#include "lsfwt.h"
+ 
+/*
+********************************************************************************
+*                         INCLUDE FILES
+********************************************************************************
+*/
+#include "typedef.h"
+#include "basic_op.h"
+#include "no_count.h"
+#include "cnst.h"
+
+/*
+********************************************************************************
+*                         PUBLIC PROGRAM CODE
+********************************************************************************
+*/
+/****************************************************
+ *
+ * FUNCTION  Lsf_wt                                                         *
+ *                                                                          *
+ ****************************************************
+ * Compute LSF weighting factors                                            *
+ *                                                                          *
+ *  d[i] = lsf[i+1] - lsf[i-1]                                              *
+ *                                                                          *
+ *  The weighting factors are approximated by two line segment.             *
+ *                                                                          *
+ *  First segment passes by the following 2 points:                         *
+ *                                                                          *
+ *     d[i] = 0Hz     wf[i] = 3.347                                         *
+ *     d[i] = 450Hz   wf[i] = 1.8                                           *
+ *                                                                          *
+ *  Second segment passes by the following 2 points:                        *
+ *                                                                          *
+ *     d[i] = 450Hz   wf[i] = 1.8                                           *
+ *     d[i] = 1500Hz  wf[i] = 1.0                                           *
+ *                                                                          *
+ *  if( d[i] < 450Hz )                                                      *
+ *    wf[i] = 3.347 - ( (3.347-1.8) / (450-0)) *  d[i]                      *
+ *  else                                                                    *
+ *    wf[i] = 1.8 - ( (1.8-1.0) / (1500-450)) *  (d[i] - 450)               *
+ *                                                                          *
+ *                                                                          *
+ *  if( d[i] < 1843)                                                        *
+ *    wf[i] = 3427 - (28160*d[i])>>15                                       *
+ *  else                                                                    *
+ *    wf[i] = 1843 - (6242*(d[i]-1843))>>15                                 *
+ *                                                                          *
+ *--------------------------------------------------------------------------*/
+
+void Lsf_wt (
+    Word16 *lsf,         /* input : LSF vector                  */
+    Word16 *wf)          /* output: square of weighting factors */
+{
+    Word16 temp;
+    Word16 i;
+    /* wf[0] = lsf[1] - 0  */
+    wf[0] = lsf[1];                                     move16 (); 
+    for (i = 1; i < 9; i++)
+    {
+        wf[i] = sub (lsf[i + 1], lsf[i - 1]);           move16 (); 
+    }
+    /* wf[9] = 0.5 - lsf[8] */    
+    wf[9] = sub (16384, lsf[8]);move16 ();      
+
+    for (i = 0; i < 10; i++)
+    {
+        temp = sub (wf[i], 1843);
+        test (); 
+        if (temp < 0)
+        {
+            wf[i] = sub (3427, mult (wf[i], 28160));    move16 (); 
+        }
+        else
+        {
+            wf[i] = sub (1843, mult (temp, 6242));      move16 (); 
+        }
+
+        wf[i] = shl (wf[i], 3); move16 (); 
+    }
+    return;
+}