fft.h

/* 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 COMMON_FFT_H
#define COMMON_FFT_H

#include "common/scummsys.h"
#include "common/math.h"

namespace Common {

class CosineTable;

class FFT {
public:
    FFT(int bits, int inverse);
    ~FFT();

    const uint16 *getRevTab() const;

    void permute(Complex *z);

    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 Common

#endif // COMMON_FFT_H