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/*
* dither.h
*
* 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.
*
*/
extern uint16_t lfsr_state;
extern const uint16_t dither_lut[256];
static inline uint16_t dither_gen(void)
{
int16_t state;
state = dither_lut[lfsr_state >> 8] ^ (lfsr_state << 8);
lfsr_state = (uint16_t) state;
return ((state * (int32_t) (0.707106 * 256.0))>>8);
}
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