/*This software module was originally developed byToshiyuki Nomura (NEC Corporation)and edited byin the course of development of theMPEG-2 NBC/MPEG-4 Audio standard ISO/IEC 13818-7, 14496-1,2 and 3.This software module is an implementation of a part of one or moreMPEG-2 NBC/MPEG-4 Audio tools as specified by the MPEG-2 NBC/MPEG-4 Audiostandard. ISO/IEC  gives users of the MPEG-2 NBC/MPEG-4 Audio standardsfree license to this software module or modifications thereof for use inhardware or software products claiming conformance to the MPEG-2 NBC/MPEG-4 Audio  standards. Those intending to use this software module inhardware or software products are advised that this use may infringeexisting patents. The original developer of this software module andhis/her company, the subsequent editors and their companies, and ISO/IEChave no liability for use of this software module or modificationsthereof in an implementation. Copyright is not released for nonMPEG-2 NBC/MPEG-4 Audio conforming products. The original developerretains full right to use the code for his/her  own purpose, assign ordonate the code to a third party and to inhibit third party from usingthe code for non MPEG-2 NBC/MPEG-4 Audio conforming products.This copyright notice must be included in all copies or derivative works.Copyright (c)1996.*//* *	MPEG-4 Audio Verification Model (LPC-ABS Core) *	 *	Excitation Gain Decoding Subroutines * *	Ver1.0	96.12.16	T.Nomura(NEC) */#include <stdio.h>#include <stdlib.h>#include <math.h>#include "nec_gain_4m6b2d.tbl"#include "nec_gain_wb_4m7b2d.tbl"#include "nec_exc_proto.h"#include "nec_abs_const.h"#include "bitstream.h"#define NEC_GAIN_DIM	2void nec_dec_gain(		  long	vu_flag,	/* input */		  float	qxnorm,		/* input */		  float	alpha[],	/* input */		  float	ac[],		/* input */		  float	comb_exc[],	/* input */		  long	len_sf,		/* configuration input */		  long	ga_idx,		/* input */		  long	lpc_order,	/* configuration input */		  long	gainbit,	/* configuration input */		  float	*g_ac,		/* output */		  float	*g_ec )		/* output */{   int		i;   long		size_gc, n_cb;   float	renorm;   float	vnorm1, vnorm2, ivnorm1, ivnorm2;   float	*par, parpar0;   float	*gcb;   /* Cofiguration Parameter Check */   n_cb = (len_sf == 40) ? 1 : 0;   if ( gainbit == NEC_BIT_GAIN ) {      gcb = nec_gc[4*n_cb+vu_flag];   } else if ( gainbit == NEC_BIT_GAIN_WB ) {      gcb = nec_wb_gc[4*n_cb+vu_flag];   } else {      printf("\n Configuration error in nec_enc_gain \n");      exit(1);   }   size_gc = 1 << gainbit;   if((par = (float *)calloc (lpc_order, sizeof(float)))==NULL) {      printf("\n Memory allocation error in nec_dec_gain \n");      exit(1);   }      nec_lpc2par(alpha, par, lpc_order);   parpar0 = 1.0;   for(i = 0; i < lpc_order; i++){      parpar0 *= (1 - par[i] * par[i]);   }   parpar0 = (parpar0 > 0.0) ? sqrt(parpar0) : 0.0;   renorm = qxnorm * parpar0;   vnorm1 = 0.0;   vnorm2 = 0.0;   for (i = 0; i < len_sf; i++) {      vnorm1 += ac[i] * ac[i];      vnorm2 += comb_exc[i] * comb_exc[i];   }   if(vnorm1 == 0.0) {      ivnorm1 = 0.0;   }   else {      ivnorm1 = 1.0 / sqrt(vnorm1);   }   if(vnorm2 == 0.0) {      ivnorm2 = 0.0;   }   else {      ivnorm2 = 1.0 / sqrt(vnorm2);   }   *g_ac = gcb[NEC_GAIN_DIM*ga_idx+0] * renorm * ivnorm1;   *g_ec = gcb[NEC_GAIN_DIM*ga_idx+1] * renorm * ivnorm2;  FREE( par );}