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