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math/cosinetables.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/>.
+ *
+ */
+
+#ifndef MATH_COSINETABLES_H
+#define MATH_COSINETABLES_H
+
+#include "common/scummsys.h"
+
+namespace Math {
+
+/**
+ * @defgroup math_cosinetables Cosine tables
+ * @ingroup math
+ *
+ * @brief  Functions for working with cosine tables.
+ *
+ * @{
+ */
+
+class CosineTable {
+public:
+	/**
+	 * Construct a cosine table given the number of points.
+	 *
+	 * @param nPoints Number of distinct radian points that must be in range [16,65536] and be divisible by 4.
+	 */
+	CosineTable(int nPoints);
+	~CosineTable();
+
+	/**
+	 * Get a pointer to a table.
+	 *
+	 * This table contains nPoints/2 entries.
+	 * Prefer to use at()
+	 * The layout of this table is as follows:
+	 * - Entries 0 up to (including) nPoints/4:
+	 *           cos(0) till (including) cos(1/2*pi)
+	 * - Entries (excluding) nPoints/4 up to nPoints/2:
+	 *           (excluding) cos(3/2*pi) till (excluding) cos(2*pi)
+	 */
+	const float *getTable() { return _tableEOS; }
+
+	/**
+	 * Return cos(2*pi * index / nPoints )
+	 * Index must be in range [0, nPoints - 1]
+	 * Faster than atLegacy.
+	 */
+	float at(int index) const;
+
+	/**
+	 * Returns cos(2*pi * index / nPoints )
+	 * Index must be in range [0, nPoints - 1]
+	 */
+	float atLegacy(int index) const;
+
+private:
+	float *_tableEOS;
+	float *_table;
+	double _radResolution; // Smallest radian increment
+	int _refSize; // _nPoints / 4
+	int _nPoints; // range of operator[]
+};
+
+/** @} */
+
+} // End of namespace Math
+
+#endif // MATH_COSINETABLES_H