/*  *    uncouple.c * *	Aaron Holtzman - May 1999 * */#include <stdlib.h>#include <stdio.h>#include "ac3.h"#include "decode.h"#include "dither.h"#include "uncouple.h"void convert_to_float(uint_16 exp, uint_16 mantissa, uint_32 *dest);void uncouple_channel(stream_coeffs_t *coeffs,audblk_t *audblk, uint_32 ch);voiduncouple(bsi_t *bsi,audblk_t *audblk,stream_coeffs_t *coeffs){	int i,j;	for(i=0; i< bsi->nfchans; i++)	{		for(j=0; j < audblk->endmant[i]; j++)			 convert_to_float(audblk->fbw_exp[i][j],audblk->chmant[i][j],					 (uint_32*) &coeffs->fbw[i][j]);	}	if(audblk->cplinu)	{		for(i=0; i< bsi->nfchans; i++)		{			if(audblk->chincpl[i])			{				uncouple_channel(coeffs,audblk,i);			}		}	}	if(bsi->lfeon)	{		/* There are always 7 mantissas for lfe */		for(j=0; j < 7 ; j++)			 convert_to_float(audblk->lfe_exp[j],audblk->lfemant[j],					 (uint_32*) &coeffs->lfe[j]);	}}voiduncouple_channel(stream_coeffs_t *coeffs,audblk_t *audblk, uint_32 ch){	uint_32 bnd = 0;	uint_32 i,j;	float cpl_coord;	float coeff;	uint_32 cpl_exp_tmp;	uint_32 cpl_mant_tmp;	for(i=audblk->cplstrtmant;i<audblk->cplendmant;)	{		if(!audblk->cplbndstrc[bnd])		{			cpl_exp_tmp = audblk->cplcoexp[ch][bnd] + 3 * audblk->mstrcplco[ch];			if(audblk->cplcoexp[ch][bnd] == 15)				cpl_mant_tmp = (audblk->cplcomant[ch][bnd]) << 12;			else				cpl_mant_tmp = ((0x10) | audblk->cplcomant[ch][bnd]) << 11;						convert_to_float(cpl_exp_tmp,cpl_mant_tmp,(uint_32*)&cpl_coord);		}		bnd++;		for(j=0;j < 12; j++)		{			//Get new dither values for each channel if necessary, so			//the channels are uncorrelated			if(audblk->dithflag[ch] && audblk->cpl_bap[i] == 0)				convert_to_float(audblk->cpl_exp[i],dither_gen(),(uint_32*)&coeff);			else				convert_to_float(audblk->cpl_exp[i], audblk->cplmant[i],(uint_32*)&coeff);			coeffs->fbw[ch][i]  = cpl_coord * coeff;			i++;		}	}}static uint_8 first_bit_lut[256] = {	0, 8, 7, 7, 6, 6, 6, 6, 5, 5, 5, 5, 5, 5, 5, 5, 	4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 	3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 	3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};/* Converts an unsigned exponent in the range of 0-24 and a 16 bit mantissa * to an IEEE single precision floating point value */void convert_to_float(uint_16 exp, uint_16 mantissa, uint_32 *dest){	uint_32 num;	uint_16 exponent;	uint_8 i;	/* If the mantissa is zero we can simply return zero */	if(mantissa == 0)	{		*dest = 0;		return;	}	/* Exponent is offset by 127 in IEEE format minus the shift to	 * align the mantissa to 1.f (subtracted in the final result) */	exponent = 127 - exp;	/* Take care of the one asymmetric negative number */	if(mantissa == 0x8000)		mantissa++;	/* Extract the sign bit, invert the mantissa if it's negative, and 	   shift out the sign bit */	if( mantissa & 0x8000 )	{		mantissa *= -2;		num = 0x80000000 + (exponent << 23);	}	else	{		mantissa *= 2;		num = exponent << 23;	}	/* Find the index of the most significant one bit */	i = first_bit_lut[mantissa >> 8];	if(i == 0)		i = first_bit_lut[mantissa & 0xff] + 8;		*dest = num - (i << 23) + (mantissa << (7 + i));}