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/*
* E-AC-3 decoder
* Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>
* Copyright (c) 2008 Justin Ruggles
*
* This file is part of FFmpeg.
*
* FFmpeg 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 of the License, or (at your option) any later version.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avcodec.h"
#include "ac3.h"
#include "ac3_parser.h"
#include "ac3dec.h"
#include "ac3dec_data.h"
/** gain adaptive quantization mode */
typedef enum {
EAC3_GAQ_NO =0,
EAC3_GAQ_12,
EAC3_GAQ_14,
EAC3_GAQ_124
} EAC3GaqMode;
#define EAC3_SR_CODE_REDUCED 3
/** lrint(M_SQRT2*cos(2*M_PI/12)*(1<<23)) */
#define COEFF_0 10273905LL
/** lrint(M_SQRT2*cos(0*M_PI/12)*(1<<23)) = lrint(M_SQRT2*(1<<23)) */
#define COEFF_1 11863283LL
/** lrint(M_SQRT2*cos(5*M_PI/12)*(1<<23)) */
#define COEFF_2 3070444LL
/**
* Calculate 6-point IDCT of the pre-mantissas.
* All calculations are 24-bit fixed-point.
*/
static void idct6(int pre_mant[6])
{
int tmp;
int even0, even1, even2, odd0, odd1, odd2;
odd1 = pre_mant[1] - pre_mant[3] - pre_mant[5];
even2 = ( pre_mant[2] * COEFF_0) >> 23;
tmp = ( pre_mant[4] * COEFF_1) >> 23;
odd0 = ((pre_mant[1] + pre_mant[5]) * COEFF_2) >> 23;
even0 = pre_mant[0] + (tmp >> 1);
even1 = pre_mant[0] - tmp;
tmp = even0;
even0 = tmp + even2;
even2 = tmp - even2;
tmp = odd0;
odd0 = tmp + pre_mant[1] + pre_mant[3];
odd2 = tmp + pre_mant[5] - pre_mant[3];
pre_mant[0] = even0 + odd0;
pre_mant[1] = even1 + odd1;
pre_mant[2] = even2 + odd2;
pre_mant[3] = even2 - odd2;
pre_mant[4] = even1 - odd1;
pre_mant[5] = even0 - odd0;
}
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