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/*
* exponent.c
*
* Copyright (C) Aaron Holtzman - May 1999
*
* This file is part of ac3dec, a free Dolby AC-3 stream decoder.
*
* ac3dec is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* ac3dec is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Make; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include <stdlib.h>
#include <stdio.h>
#include "ac3.h"
#include "ac3_internal.h"
#include "decode.h"
#include "exponent.h"
static void exp_unpack_ch(uint_16 type,uint_16 expstr,uint_16 ngrps,uint_16 initial_exp,
uint_16 exps[], uint_16 *dest);
void
exponent_unpack( bsi_t *bsi, audblk_t *audblk)
{
uint_16 i;
for(i=0; i< bsi->nfchans; i++)
exp_unpack_ch(UNPACK_FBW, audblk->chexpstr[i], audblk->nchgrps[i], audblk->exps[i][0],
&audblk->exps[i][1], audblk->fbw_exp[i]);
if(audblk->cplinu)
exp_unpack_ch(UNPACK_CPL, audblk->cplexpstr, audblk->ncplgrps, audblk->cplabsexp << 1,
audblk->cplexps, &audblk->cpl_exp[audblk->cplstrtmant]);
if(bsi->lfeon)
exp_unpack_ch(UNPACK_LFE, audblk->lfeexpstr, 2, audblk->lfeexps[0],
&audblk->lfeexps[1], audblk->lfe_exp);
}
static void
exp_unpack_ch(uint_16 type,uint_16 expstr,uint_16 ngrps,uint_16 initial_exp,
uint_16 exps[], uint_16 *dest)
{
uint_16 i,j;
sint_16 exp_acc;
sint_16 exp_1,exp_2,exp_3;
if(expstr == EXP_REUSE)
return;
/* Handle the initial absolute exponent */
exp_acc = initial_exp;
j = 0;
/* In the case of a fbw channel then the initial absolute values is
* also an exponent */
if(type != UNPACK_CPL)
dest[j++] = exp_acc;
/* Loop through the groups and fill the dest array appropriately */
for(i=0; i< ngrps; i++)
{
if(exps[i] > 124)
goto error;
exp_1 = exps[i] / 25;
exp_2 = (exps[i] - (exp_1 * 25)) / 5;
exp_3 = exps[i] - (exp_1 * 25) - (exp_2 * 5) ;
exp_acc += (exp_1 - 2);
switch(expstr)
{
case EXP_D45:
dest[j++] = exp_acc;
dest[j++] = exp_acc;
case EXP_D25:
dest[j++] = exp_acc;
case EXP_D15:
dest[j++] = exp_acc;
}
exp_acc += (exp_2 - 2);
switch(expstr)
{
case EXP_D45:
dest[j++] = exp_acc;
dest[j++] = exp_acc;
case EXP_D25:
dest[j++] = exp_acc;
case EXP_D15:
dest[j++] = exp_acc;
}
exp_acc += (exp_3 - 2);
switch(expstr)
{
case EXP_D45:
dest[j++] = exp_acc;
dest[j++] = exp_acc;
case EXP_D25:
dest[j++] = exp_acc;
case EXP_D15:
dest[j++] = exp_acc;
}
}
return;
goto error;
error:
if(!error_flag)
fprintf(stderr,"** Invalid exponent - skipping frame **\n");
error_flag = 1;
}
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