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authorMatthew Hoops2011-07-02 15:23:49 -0400
committerMatthew Hoops2011-07-02 15:23:49 -0400
commit3aefa913faaf2a98512f02b0581ca8a077876b84 (patch)
tree9bc5436e68e1dd83bf5013f181ef864c5c35e2d2 /common/fft.h
parent0aa58b9033ee83b3008a7f4ac48d10baa6c7335d (diff)
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COMMON: Add an FFT math handler
Based on eos' code which is based on FFmpeg's code
Diffstat (limited to 'common/fft.h')
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1 files changed, 73 insertions, 0 deletions
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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. */
+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;
+
+ const float *_tSin;
+ const float *_tCos;
+
+ int _splitRadix;
+ int _permutation;
+
+ static int splitRadixPermutation(int i, int n, int inverse);
+};
+
+} // End of namespace Common
+
+#endif // COMMON_FFT_H