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https://github.com/libretro/scummvm.git
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96 lines
2.1 KiB
C++
96 lines
2.1 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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// Based on eos' (I)FFT code which is in turn
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// based upon the (I)FFT code in FFmpeg
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// Copyright (c) 2008 Loren Merritt
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// Copyright (c) 2002 Fabrice Bellard
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// Partly based on libdjbfft by D. J. Bernstein
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#ifndef MATH_FFT_H
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#define MATH_FFT_H
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#include "common/scummsys.h"
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namespace Math {
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/**
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* @defgroup math_fft Fast Fourier Transform (FFT)
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* @ingroup math
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*
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* @brief API for the FFT algorithm.
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*
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* @{
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*/
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class CosineTable;
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struct Complex;
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/**
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* (Inverse) Fast Fourier Transform.
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*
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* Used in engines:
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* - SCUMM
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*/
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class FFT {
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public:
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FFT(int bits, int inverse);
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~FFT();
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const uint16 *getRevTab() const;
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/** Perform the permutation needed BEFORE calling calc(). */
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void permute(Complex *z);
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/** Perform a complex FFT.
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*
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* The input data must be permuted before.
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* No 1.0/sqrt(n) normalization is done.
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*/
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void calc(Complex *z);
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private:
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int _bits;
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int _inverse;
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uint16 *_revTab;
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Complex *_expTab;
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Complex *_tmpBuf;
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int _splitRadix;
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static int splitRadixPermutation(int i, int n, int inverse);
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CosineTable *_cosTables[13];
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void fft4(Complex *z);
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void fft8(Complex *z);
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void fft16(Complex *z);
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void fft(int n, int logn, Complex *z);
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};
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/** @} */
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} // End of namespace Math
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#endif // MATH_FFT_H
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