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diff --git a/common/frac.h b/common/frac.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 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.
+ *
+ * $URL$
+ * $Id$
+ *
+ */
+
+#ifndef COMMON_FRAC_H
+#define COMMON_FRAC_H
+
+#include "common/scummsys.h"
+
+/**
+ * The precision of the fractional (fixed point) type we define below.
+ * Normally you should never have to modify this value.
+ */
+enum {
+	FRAC_BITS = 16,
+	FRAC_LO_MASK = ((1L << FRAC_BITS) - 1),
+	FRAC_HI_MASK = ((1L << FRAC_BITS) - 1) << FRAC_BITS,
+
+	FRAC_ONE = (1L << FRAC_BITS),		// 1.0
+	FRAC_HALF = (1L << (FRAC_BITS-1))	// 0.5
+};
+
+/**
+ * Fixed-point fractions, used by the sound rate converter and other code.
+ */
+typedef int32 frac_t;
+
+inline frac_t doubleToFrac(double value) { return (frac_t)(value * FRAC_ONE); }
+inline double fracToDouble(frac_t value) { return ((double)value) / FRAC_ONE; }
+
+inline frac_t intToFrac(int16 value) { return value << FRAC_BITS; }
+inline int16 fracToInt(frac_t value) { return value >> FRAC_BITS; }
+
+#endif