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math/mdct.h

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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 xoreos' (I)RDFT code which is in turn
+// Based upon the (I)MDCT code in FFmpeg
+// Copyright (c) 2002 Fabrice Bellard
+
+
+#ifndef MATH_MDCT_H
+#define MATH_MDCT_H
+
+#include "common/scummsys.h"
+
+namespace Math {
+
+class FFT;
+
+/** (Inverse) Modified Discrete Cosine Transforms. */
+class MDCT {
+public:
+	MDCT(int bits, bool inverse, double scale);
+	~MDCT();
+
+	/** Compute MDCT of size N = 2^nbits. */
+	void calcMDCT(float *output, const float *input);
+
+	/** Compute inverse MDCT of size N = 2^nbits. */
+	void calcIMDCT(float *output, const float *input);
+
+private:
+	int _bits;
+	int _size;
+
+	float *_tCos;
+	float *_tSin;
+
+	FFT *_fft;
+
+	/** Compute the middle half of the inverse MDCT of size N = 2^nbits,
+	 *  thus excluding the parts that can be derived by symmetry.
+	 */
+	void calcHalfIMDCT(float *output, const float *input);
+};
+
+} // End of namespace Math
+
+#endif // MATH_MDCT_H