--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtwamr/calc_cor.c	Thu Apr 18 20:12:48 2024 +0000
@@ -0,0 +1,78 @@
+/*
+********************************************************************************
+*
+*      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             : calc_cor.c
+*      Purpose          : Calculate all correlations for prior the OL LTP 
+*
+********************************************************************************
+*/
+
+/*
+********************************************************************************
+*                         MODULE INCLUDE FILE AND VERSION ID
+********************************************************************************
+*/
+#include "namespace.h"
+#include "calc_cor.h"
+
+/*
+********************************************************************************
+*                         INCLUDE FILES
+********************************************************************************
+*/
+#include "typedef.h"
+#include "basic_op.h"
+#include "oper_32b.h"
+#include "no_count.h"
+#include "cnst.h"
+
+/*
+********************************************************************************
+*                         PUBLIC PROGRAM CODE
+********************************************************************************
+*/
+/*************************************************************************
+ *
+ *  FUNCTION: comp_corr 
+ *
+ *  PURPOSE: Calculate all correlations of scal_sig[] in a given delay
+ *           range.
+ *
+ *  DESCRIPTION:
+ *      The correlation is given by
+ *           cor[t] = <scal_sig[n],scal_sig[n-t]>,  t=lag_min,...,lag_max
+ *      The functions outputs the all correlations 
+ *
+ *************************************************************************/
+void comp_corr ( 
+    Word16 scal_sig[],  /* i   : scaled signal.                          */
+    Word16 L_frame,     /* i   : length of frame to compute pitch        */
+    Word16 lag_max,     /* i   : maximum lag                             */
+    Word16 lag_min,     /* i   : minimum lag                             */
+    Word32 corr[])      /* o   : correlation of selected lag             */
+{
+    Word16 i, j;
+    Word16 *p, *p1;
+    Word32 t0;
+    
+    for (i = lag_max; i >= lag_min; i--)
+    {
+       p = scal_sig;           move16 (); 
+       p1 = &scal_sig[-i];     move16 (); 
+       t0 = 0;                 move32 (); 
+       
+       for (j = 0; j < L_frame; j++, p++, p1++)
+       {
+          t0 = L_mac (t0, *p, *p1);             
+       }
+       corr[-i] = t0;          move32 ();
+    }
+
+    return;
+}