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fft.h

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00001 /* ScummVM - Graphic Adventure Engine
00002  *
00003  * ScummVM is the legal property of its developers, whose names
00004  * are too numerous to list here. Please refer to the COPYRIGHT
00005  * file distributed with this source distribution.
00006  *
00007  * This program is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU General Public License
00009  * as published by the Free Software Foundation; either version 2
00010  * of the License, or (at your option) any later version.
00011  *
00012  * This program is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015  * GNU General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU General Public License
00018  * along with this program; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
00020  *
00021  */
00022 
00023 // Based on eos' (I)FFT code which is in turn
00024 // based upon the (I)FFT code in FFmpeg
00025 // Copyright (c) 2008 Loren Merritt
00026 // Copyright (c) 2002 Fabrice Bellard
00027 // Partly based on libdjbfft by D. J. Bernstein
00028 
00029 #ifndef COMMON_FFT_H
00030 #define COMMON_FFT_H
00031 
00032 #include "common/scummsys.h"
00033 #include "common/math.h"
00034 
00035 namespace Common {
00036 
00037 class CosineTable;
00038 
00045 class FFT {
00046 public:
00047     FFT(int bits, int inverse);
00048     ~FFT();
00049 
00050     const uint16 *getRevTab() const;
00051 
00053     void permute(Complex *z);
00054 
00060     void calc(Complex *z);
00061 
00062 private:
00063     int _bits;
00064     int _inverse;
00065 
00066     uint16 *_revTab;
00067 
00068     Complex *_expTab;
00069     Complex *_tmpBuf;
00070 
00071     int _splitRadix;
00072 
00073     static int splitRadixPermutation(int i, int n, int inverse);
00074 
00075     CosineTable *_cosTables[13];
00076 
00077     void fft4(Complex *z);
00078     void fft8(Complex *z);
00079     void fft16(Complex *z);
00080     void fft(int n, int logn, Complex *z);
00081 };
00082 
00083 } // End of namespace Common
00084 
00085 #endif // COMMON_FFT_H


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