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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program 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.
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
// Based on eos' (I)FFT code which is in turn
// based upon the (I)FFT code in FFmpeg
// Copyright (c) 2008 Loren Merritt
// Copyright (c) 2002 Fabrice Bellard
// Partly based on libdjbfft by D. J. Bernstein
#ifndef COMMON_FFT_H
#define COMMON_FFT_H
#include "common/scummsys.h"
#include "common/math.h"
namespace Common {
/**
* (Inverse) Fast Fourier Transform.
*
* Used in engines:
* - scumm
*/
class FFT {
public:
FFT(int bits, int inverse);
~FFT();
/** Do the permutation needed BEFORE calling calc(). */
void permute(Complex *z);
/** Do a complex FFT.
*
* The input data must be permuted before.
* No 1.0/sqrt(n) normalization is done.
*/
void calc(Complex *z);
private:
int _bits;
int _inverse;
uint16 *_revTab;
Complex *_expTab;
Complex *_tmpBuf;
int _splitRadix;
int _permutation;
static int splitRadixPermutation(int i, int n, int inverse);
};
} // End of namespace Common
#endif // COMMON_FFT_H
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