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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 3 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, see <http://www.gnu.org/licenses/>.
*
*/
// 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 MATH_FFT_H
#define MATH_FFT_H
#include "common/scummsys.h"
namespace Math {
/**
* @defgroup math_fft Fast Fourier Transform (FFT)
* @ingroup math
*
* @brief API for the FFT algorithm.
*
* @{
*/
class CosineTable;
struct Complex;
/**
* (Inverse) Fast Fourier Transform.
*
* Used in engines:
* - SCUMM
*/
class FFT {
public:
FFT(int bits, int inverse);
~FFT();
const uint16 *getRevTab() const;
/** Perform the permutation needed BEFORE calling calc(). */
void permute(Complex *z);
/** Perform 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;
static int splitRadixPermutation(int i, int n, int inverse);
CosineTable *_cosTables[13];
void fft4(Complex *z);
void fft8(Complex *z);
void fft16(Complex *z);
void fft(int n, int logn, Complex *z);
};
/** @} */
} // End of namespace Math
#endif // MATH_FFT_H
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