--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtwamr/hp_max.c	Mon May 06 05:10:03 2024 +0000
@@ -0,0 +1,121 @@
+/*
+********************************************************************************
+*
+*      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             : hp_max.c
+*      Purpose          : Find the maximum correlation of scal_sig[] in a given
+*                         delay range.
+*
+********************************************************************************
+*/
+
+/*
+********************************************************************************
+*                         MODULE INCLUDE FILE AND VERSION ID
+********************************************************************************
+*/
+#include "namespace.h"
+#include "hp_max.h"
+
+/*
+********************************************************************************
+*                         INCLUDE FILES
+********************************************************************************
+*/
+#include "typedef.h"
+#include "basic_op.h"
+#include "oper_32b.h"
+#include "no_count.h"
+#include "cnst.h"
+
+/*
+********************************************************************************
+*                         PUBLIC PROGRAM CODE
+********************************************************************************
+*/
+Word16 hp_max (  
+    Word32 corr[],      /* i   : correlation vector.                      */
+    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                              */
+    Word16 *cor_hp_max) /* o   : max high-pass filtered norm. correlation */
+{
+    Word16 i;
+    Word16 *p, *p1;
+    Word32 max, t0, t1;
+    Word16 max16, t016, cor_max;
+    Word16 shift, shift1, shift2;
+    
+    max = MIN_32;               move32 (); 
+    t0 = 0L;                    move32 ();    
+   
+    for (i = lag_max-1; i > lag_min; i--)
+    {
+       /* high-pass filtering */
+       t0 = L_sub (L_sub(L_shl(corr[-i], 1), corr[-i-1]), corr[-i+1]);   
+       t0 = L_abs (t0);
+       
+       test (); 
+       if (L_sub (t0, max) >= 0)
+       {
+          max = t0;             move32 (); 
+       }
+    }
+
+    /* compute energy */
+    p = scal_sig;               move16 (); 
+    p1 = &scal_sig[0];          move16 (); 
+    t0 = 0L;                    move32 (); 
+    for (i = 0; i < L_frame; i++, p++, p1++)
+    {
+       t0 = L_mac (t0, *p, *p1);
+    }
+
+    p = scal_sig;               move16 (); 
+    p1 = &scal_sig[-1];         move16 (); 
+    t1 = 0L;                    move32 (); 
+    for (i = 0; i < L_frame; i++, p++, p1++)
+    {
+       t1 = L_mac (t1, *p, *p1);
+    }
+    
+    /* high-pass filtering */
+    t0 = L_sub(L_shl(t0, 1), L_shl(t1, 1));
+    t0 = L_abs (t0);
+
+    /* max/t0 */
+    shift1 = sub(norm_l(max), 1);                 
+    max16  = extract_h(L_shl(max, shift1));       
+    shift2 = norm_l(t0);                          
+    t016 =  extract_h(L_shl(t0, shift2));         
+
+    test ();
+    if (t016 != 0)
+    {
+       cor_max = div_s(max16, t016);              
+    }
+    else
+    {
+       cor_max = 0;                                move16 ();
+    }
+    
+    shift = sub(shift1, shift2);       
+
+    test ();
+    if (shift >= 0)
+    {
+       *cor_hp_max = shr(cor_max, shift);          move16 (); /* Q15 */
+    }
+    else
+    {
+       *cor_hp_max = shl(cor_max, negate(shift));  move16 (); /* Q15 */
+    }
+
+    return 0;
+}