--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtwamr/cl_ltp.c	Mon May 06 23:32:59 2024 +0000
@@ -0,0 +1,182 @@
+/*
+*****************************************************************************
+*
+*      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             : cl_ltp.c
+*
+*****************************************************************************
+*/
+
+/*
+*****************************************************************************
+*                         MODULE INCLUDE FILE AND VERSION ID
+*****************************************************************************
+*/
+#include "namespace.h"
+#include "cl_ltp.h"
+ 
+/*
+*****************************************************************************
+*                         INCLUDE FILES
+*****************************************************************************
+*/
+#include <stddef.h>
+#include "typedef.h"
+#include "basic_op.h"
+#include "no_count.h"
+#include "oper_32b.h"
+#include "cnst.h"
+#include "convolve.h"
+#include "g_pitch.h"
+#include "pred_lt.h"
+#include "pitch_fr.h"
+#include "enc_lag3.h"
+#include "enc_lag6.h"
+#include "q_gain_p.h"
+#include "ton_stab.h"
+
+/*
+*****************************************************************************
+*                         LOCAL VARIABLES AND TABLES
+*****************************************************************************
+*/
+
+/*
+*****************************************************************************
+*                         PUBLIC PROGRAM CODE
+*****************************************************************************
+*/
+ 
+/*************************************************************************
+*
+*  Function:   cl_ltp_reset
+*  Purpose:    Initializes state memory to zero
+*
+**************************************************************************
+*/
+void cl_ltp_reset (clLtpState *state)
+{
+    /* Reset pitch search states */
+    Pitch_fr_reset (&state->pitchSt);
+}
+
+/*************************************************************************
+*
+*  Function:   cl_ltp
+*  Purpose:    closed-loop fractional pitch search
+*
+**************************************************************************
+*/
+int cl_ltp (
+    clLtpState *clSt,    /* i/o : State struct                              */
+    tonStabState *tonSt, /* i/o : State struct                              */
+    enum Mode mode,      /* i   : coder mode                                */
+    Word16 frameOffset,  /* i   : Offset to subframe                        */
+    Word16 T_op[],       /* i   : Open loop pitch lags                      */
+    Word16 *h1,          /* i   : Impulse response vector               Q12 */
+    Word16 *exc,         /* i/o : Excitation vector                      Q0 */
+    Word16 res2[],       /* i/o : Long term prediction residual          Q0 */
+    Word16 xn[],         /* i   : Target vector for pitch search         Q0 */
+    Word16 lsp_flag,     /* i   : LSP resonance flag                        */
+    Word16 xn2[],        /* o   : Target vector for codebook search      Q0 */
+    Word16 y1[],         /* o   : Filtered adaptive excitation           Q0 */
+    Word16 *T0,          /* o   : Pitch delay (integer part)                */
+    Word16 *T0_frac,     /* o   : Pitch delay (fractional part)             */
+    Word16 *gain_pit,    /* o   : Pitch gain                            Q14 */
+    Word16 g_coeff[],    /* o   : Correlations between xn, y1, & y2         */
+    Word16 **anap,       /* o   : Analysis parameters                       */
+    Word16 *gp_limit     /* o   : pitch gain limit                          */
+)
+{
+    Word16 i;
+    Word16 index;
+    Word32 L_temp;     /* temporarily variable */
+    Word16 resu3;      /* flag for upsample resolution */
+    Word16 gpc_flag;
+    
+   /*----------------------------------------------------------------------*
+    *                 Closed-loop fractional pitch search                  *
+    *----------------------------------------------------------------------*/
+   *T0 = Pitch_fr(&clSt->pitchSt,
+                  mode, T_op, exc, xn, h1, 
+                  L_SUBFR, frameOffset,
+                  T0_frac, &resu3, &index); move16 ();
+   
+   *(*anap)++ = index;                              move16 ();
+   
+   /*-----------------------------------------------------------------*
+    *   - find unity gain pitch excitation (adapitve codebook entry)  *
+    *     with fractional interpolation.                              *
+    *   - find filtered pitch exc. y1[]=exc[] convolve with h1[])     *
+    *   - compute pitch gain and limit between 0 and 1.2              *
+    *   - update target vector for codebook search                    *
+    *   - find LTP residual.                                          *
+    *-----------------------------------------------------------------*/
+   
+   Pred_lt_3or6(exc, *T0, *T0_frac, L_SUBFR, resu3);
+   
+   Convolve(exc, h1, y1, L_SUBFR);
+   
+   /* gain_pit is Q14 for all modes */
+   *gain_pit = G_pitch(mode, xn, y1, g_coeff, L_SUBFR); move16 ();
+
+   
+   /* check if the pitch gain should be limit due to resonance in LPC filter */
+   gpc_flag = 0;                                        move16 ();
+   *gp_limit = MAX_16;                                  move16 ();
+   test (); test ();
+   if ((lsp_flag != 0) &&
+       (sub(*gain_pit, GP_CLIP) > 0))
+   {
+       gpc_flag = check_gp_clipping(tonSt, *gain_pit);  move16 ();
+   }
+
+   /* special for the MR475, MR515 mode; limit the gain to 0.85 to */
+   /* cope with bit errors in the decoder in a better way.         */
+   test (); test (); 
+   if ((sub (mode, MR475) == 0) || (sub (mode, MR515) == 0)) {
+      test ();
+      if ( sub (*gain_pit, 13926) > 0) {
+         *gain_pit = 13926;   /* 0.85 in Q14 */    move16 ();
+      }
+
+      test ();
+      if (gpc_flag != 0) {
+          *gp_limit = GP_CLIP;                     move16 ();
+      }
+   }
+   else
+   {
+       test ();
+       if (gpc_flag != 0)
+       {
+           *gp_limit = GP_CLIP;                    move16 ();
+           *gain_pit = GP_CLIP;                    move16 ();
+       }           
+       /* For MR122, gain_pit is quantized here and not in gainQuant */
+       if (test (), sub(mode, MR122)==0)
+       {
+           *(*anap)++ = q_gain_pitch(MR122, *gp_limit, gain_pit,
+                                     NULL, NULL);
+                                                   move16 ();
+       }
+   }
+
+   /* update target vector und evaluate LTP residual */
+   for (i = 0; i < L_SUBFR; i++) {
+       L_temp = L_mult(y1[i], *gain_pit);
+       L_temp = L_shl(L_temp, 1);
+       xn2[i] = sub(xn[i], extract_h(L_temp));     move16 ();
+      
+       L_temp = L_mult(exc[i], *gain_pit);
+       L_temp = L_shl(L_temp, 1);
+       res2[i] = sub(res2[i], extract_h(L_temp));  move16 ();
+   }
+   
+   return 0;
+}