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/*
*
* exponents.c Copyright (C) Aaron Holtzman - May 1999
*
* This file is part of libmpeg3
*
* libmpeg3 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.
*
* libmpeg3 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.
*
*/
#define MIN(x, y) ((x) > (y) ? (y) : (x))
#include "mpeg3audio.h"
#include <stdio.h>
/* Exponent defines */
#define UNPACK_FBW 1
#define UNPACK_CPL 2
#define UNPACK_LFE 4
static inline int mpeg3audio_ac3_exp_unpack_ch(unsigned int type,
unsigned int expstr,
unsigned int ngrps,
unsigned int initial_exp,
unsigned short exps[],
unsigned short *dest)
{
int i, j;
int exp_acc;
int exp_1, exp_2, exp_3;
if(expstr == MPEG3_EXP_REUSE)
return 0;
/* Handle the initial absolute exponent */
exp_acc = initial_exp;
j = 0;
/* In the case of a fbw channel then the initial absolute value 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)
{
// fprintf(stderr, "mpeg3audio_ac3_exp_unpack_ch: Invalid exponent %d\n", exps[i]);
return 1;
}
exp_1 = exps[i] / 25;
exp_2 = (exps[i] % 25) / 5;
exp_3 = (exps[i] % 25) % 5;
exp_acc += (exp_1 - 2);
switch(expstr)
{
case MPEG3_EXP_D45:
j = MIN(255, j);
dest[j++] = exp_acc;
j = MIN(255, j);
dest[j++] = exp_acc;
case MPEG3_EXP_D25:
j = MIN(255, j);
dest[j++] = exp_acc;
case MPEG3_EXP_D15:
j = MIN(255, j);
dest[j++] = exp_acc;
}
exp_acc += (exp_2 - 2);
switch(expstr)
{
case MPEG3_EXP_D45:
j = MIN(255, j);
dest[j++] = exp_acc;
j = MIN(255, j);
dest[j++] = exp_acc;
case MPEG3_EXP_D25:
j = MIN(255, j);
dest[j++] = exp_acc;
case MPEG3_EXP_D15:
j = MIN(255, j);
dest[j++] = exp_acc;
}
exp_acc += (exp_3 - 2);
switch(expstr)
{
case MPEG3_EXP_D45:
j = MIN(255, j);
dest[j++] = exp_acc;
j = MIN(255, j);
dest[j++] = exp_acc;
case MPEG3_EXP_D25:
j = MIN(255, j);
dest[j++] = exp_acc;
case MPEG3_EXP_D15:
j = MIN(255, j);
dest[j++] = exp_acc;
}
}
return 0;
}
int mpeg3audio_ac3_exponent_unpack(mpeg3audio_t *audio,
mpeg3_ac3bsi_t *bsi,
mpeg3_ac3audblk_t *audblk)
{
int i, result = 0;
for(i = 0; i < bsi->nfchans; i++)
result |= mpeg3audio_ac3_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 && !result)
result |= mpeg3audio_ac3_exp_unpack_ch(UNPACK_CPL,
audblk->cplexpstr,
audblk->ncplgrps,
audblk->cplabsexp << 1,
audblk->cplexps,
&audblk->cpl_exp[audblk->cplstrtmant]);
if(bsi->lfeon && !result)
result |= mpeg3audio_ac3_exp_unpack_ch(UNPACK_LFE,
audblk->lfeexpstr,
2,
audblk->lfeexps[0],
&audblk->lfeexps[1],
audblk->lfe_exp);
return result;
}
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