/*

 * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische

 * Universitaet Berlin.  See the accompanying file "COPYRIGHT" for

 * details.  THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.

 */

/* $Header: /tmp_amd/presto/export/kbs/jutta/src/gsm/RCS/code.c,v 1.3 1996/07/02 09:59:05 jutta Exp $ */

#include	"config.h"

#include	<string.h>

#ifdef	HAS_STDLIB_H

#include	<stdlib.h>

#else

#	include "proto.h"

	extern char	* memcpy P((char *, char *, int));

#endif

#include	"private.h"

#include	"gsm.h"

#include	"proto.h"

/* 

 *  4.2 FIXED POINT IMPLEMENTATION OF THE RPE-LTP CODER 

 */

void Gsm_Coder P8((S,s,LARc,Nc,bc,Mc,xmaxc,xMc),

	struct gsm_state	* S,

	word	* s,	/* [0..159] samples		  	IN	*/

/*

 * The RPE-LTD coder works on a frame by frame basis.  The length of

 * the frame is equal to 160 samples.  Some computations are done

 * once per frame to produce at the output of the coder the

 * LARc[1..8] parameters which are the coded LAR coefficients and 

 * also to realize the inverse filtering operation for the entire

 * frame (160 samples of signal d[0..159]).  These parts produce at

 * the output of the coder:

 */

	word	* LARc,	/* [0..7] LAR coefficients		OUT	*/

/*

 * Procedure 4.2.11 to 4.2.18 are to be executed four times per

 * frame.  That means once for each sub-segment RPE-LTP analysis of

 * 40 samples.  These parts produce at the output of the coder:

 */

	word	* Nc,	/* [0..3] LTP lag			OUT 	*/

	word	* bc,	/* [0..3] coded LTP gain		OUT 	*/

	word	* Mc,	/* [0..3] RPE grid selection		OUT     */

	word	* xmaxc,/* [0..3] Coded maximum amplitude	OUT	*/

	word	* xMc	/* [13*4] normalized RPE samples	OUT	*/

)

{

	int	k;

	word	* dp  = S->dp0 + 120;	/* [ -120...-1 ] */

	word	* dpp = dp;		/* [ 0...39 ]	 */

	static word e[50];

	word	so[160];

	Gsm_Preprocess			(S, s, so);

	Gsm_LPC_Analysis		(S, so, LARc);

	Gsm_Short_Term_Analysis_Filter	(S, LARc, so);

	for (k = 0; k <= 3; k++, xMc += 13) {

		Gsm_Long_Term_Predictor	( S,

					 so+k*40, /* d      [0..39] IN	*/

					 dp,	  /* dp  [-120..-1] IN	*/

					e + 5,	  /* e      [0..39] OUT	*/

					dpp,	  /* dpp    [0..39] OUT */

					 Nc++,

					 bc++);

		Gsm_RPE_Encoding	( S,

					e + 5,	/* e	  ][0..39][ IN/OUT */

					  xmaxc++, Mc++, xMc );

		/*

		 * Gsm_Update_of_reconstructed_short_time_residual_signal

		 *			( dpp, e + 5, dp );

		 */

		{ register int i;

		  register longword ltmp;

		  for (i = 0; i <= 39; i++)

			dp[ i ] = GSM_ADD( e[5 + i], dpp[i] );

		}

		dp  += 40;

		dpp += 40;

	}

	(void)memcpy( (char *)S->dp0, (char *)(S->dp0 + 160),

		120 * sizeof(*S->dp0) );

}