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diff --git a/common/rational.cpp b/common/rational.cpp
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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.
+ *
+ * $URL$
+ * $Id$
+ */
+
+#include "common/rational.h"
+#include "common/util.h"
+#include "common/algorithm.h"
+
+namespace Common {
+
+Rational::Rational() {
+	_num   = 1;
+	_denom = 1;
+}
+
+Rational::Rational(int num) {
+	_num   = num;
+	_denom = 1;
+}
+
+Rational::Rational(int num, int denom) {
+	assert(denom != 0);
+
+	_num   = num;
+	_denom = denom;
+
+	normalize();
+}
+
+void Rational::cancel() {
+	// Cancel the fraction by dividing both the num and the denom
+	// by their greatest common denom.
+
+	int gcd = Common::gcd(_num, _denom);
+
+	_num   /= gcd;
+	_denom /= gcd;
+}
+
+void Rational::normalize() {
+	// Is the fraction negative?
+	bool negative = !((!(_num < 0)) == (!(_denom < 0)));
+
+	// Make both integers positive
+	_num   = ABS(_num);
+	_denom = ABS(_denom);
+
+	// Cancel the fraction
+	cancel();
+
+	// If the fraction is supposed to be negative, make the num negative
+	if (negative)
+		_num = -_num;
+}
+
+Rational &Rational::operator=(const Rational &right) {
+	_num   = right._num;
+	_denom = right._denom;
+
+	return *this;
+}
+
+Rational &Rational::operator=(int right) {
+	_num   = right;
+	_denom = 1;
+
+	return *this;
+}
+
+Rational &Rational::operator+=(const Rational &right) {
+	_num   = _num * right._denom + right._num * _denom;
+	_denom = _denom * right._denom;
+
+	normalize();
+
+	return *this;
+}
+
+Rational &Rational::operator-=(const Rational &right) {
+	_num   = _num * right._denom - right._num * _denom;
+	_denom = _denom * right._denom;
+
+	normalize();
+
+	return *this;
+}
+
+Rational &Rational::operator*=(const Rational &right) {
+	// Try to cross-cancel first, to avoid unnecessary overflow
+	int gcd1 = Common::gcd(_num, right._denom);
+	int gcd2 = Common::gcd(right._num, _denom);
+
+	_num   = (_num    / gcd1) * (right._num    / gcd2);
+	_denom = (_denom  / gcd2) * (right._denom  / gcd1);
+
+	normalize();
+
+	return *this;
+}
+
+Rational &Rational::operator/=(const Rational &right) {
+	return *this *= Rational(right._denom, right._num);
+}
+
+Rational &Rational::operator+=(int right) {
+	return *this += Rational(right);
+}
+
+Rational &Rational::operator-=(int right) {
+	return *this -= Rational(right);
+}
+
+Rational &Rational::operator*=(int right) {
+	return *this *= Rational(right);
+}
+
+Rational &Rational::operator/=(int right) {
+	return *this /= Rational(right);
+}
+
+const Rational Rational::operator-() const {
+	return Rational(-_num, _denom);
+}
+
+const Rational Rational::operator+(const Rational &right) const {
+	Rational tmp = *this;
+
+	tmp += right;
+
+	return tmp;
+}
+
+const Rational Rational::operator-(const Rational &right) const {
+	Rational tmp = *this;
+
+	tmp -= right;
+
+	return tmp;
+}
+
+const Rational Rational::operator*(const Rational &right) const {
+	Rational tmp = *this;
+
+	tmp *= right;
+
+	return tmp;
+}
+
+const Rational Rational::operator/(const Rational &right) const {
+	Rational tmp = *this;
+
+	tmp /= right;
+
+	return tmp;
+}
+
+const Rational Rational::operator+(int right) const {
+	Rational tmp = *this;
+
+	tmp += right;
+
+	return tmp;
+}
+
+const Rational Rational::operator-(int right) const {
+	Rational tmp = *this;
+
+	tmp -= right;
+
+	return tmp;
+}
+
+const Rational Rational::operator*(int right) const {
+	Rational tmp = *this;
+
+	tmp *= right;
+
+	return tmp;
+}
+
+const Rational Rational::operator/(int right) const {
+	Rational tmp = *this;
+
+	tmp /= right;
+
+	return tmp;
+}
+
+bool Rational::operator==(const Rational &right) const {
+	return (_num == right._num) && (_denom == right._denom);
+}
+
+bool Rational::operator!=(const Rational &right) const {
+	return (_num != right._num) || (_denom != right._denom);
+}
+
+bool Rational::operator>(const Rational &right) const {
+	return (_num * right._denom) > (right._num * _denom);
+}
+
+bool Rational::operator<(const Rational &right) const {
+	return (_num * right._denom) < (right._num * _denom);
+}
+
+bool Rational::operator>=(const Rational &right) const {
+	return (_num * right._denom) >= (right._num * _denom);
+}
+
+bool Rational::operator<=(const Rational &right) const {
+	return (_num * right._denom) <= (right._num * _denom);
+}
+
+bool Rational::operator==(int right) const {
+	return (_denom == 1) && (_num == right);
+}
+
+bool Rational::operator!=(int right) const {
+	return (_denom == 1) && (_num != right);
+}
+
+bool Rational::operator>(int right) const {
+	return *this > Rational(right, 1);
+}
+
+bool Rational::operator<(int right) const {
+	return *this < Rational(right, 1);
+}
+
+bool Rational::operator>=(int right) const {
+	return *this >= Rational(right, 1);
+}
+
+bool Rational::operator<=(int right) const {
+	return *this <= Rational(right, 1);
+}
+
+void Rational::invert() {
+	assert(_num != 0);
+
+	SWAP(_num, _denom);
+
+	normalize();
+}
+
+Rational Rational::getInverse() const {
+	Rational inverse = *this;
+
+	inverse.invert();
+
+	return inverse;
+}
+
+int Rational::toInt() const {
+	assert(_denom != 0);
+
+	return _num / _denom;
+}
+
+double Rational::toDouble() const {
+	assert(_denom != 0);
+
+	return ((double) _num) / ((double) _denom);
+}
+
+frac_t Rational::toFrac() const {
+	return (_num * FRAC_ONE) / _denom;
+}
+
+Rational::operator int() const {
+	return toInt();
+}
+
+Rational::operator double() const {
+	return toDouble();
+}
+
+const Rational operator+(int left, const Rational &right) {
+	Rational tmp = right;
+
+	tmp += left;
+
+	return tmp;
+}
+
+const Rational operator-(int left, const Rational &right) {
+	Rational tmp = right;
+
+	tmp -= left;
+
+	return tmp;
+}
+
+const Rational operator*(int left, const Rational &right) {
+	Rational tmp = right;
+
+	tmp *= left;
+
+	return tmp;
+}
+
+const Rational operator/(int left, const Rational &right) {
+	Rational tmp = right;
+
+	tmp /= left;
+
+	return tmp;
+}
+
+bool operator==(int left, const Rational &right) {
+	return right == left;
+}
+
+bool operator!=(int left, const Rational &right) {
+	return right != left;
+}
+
+bool operator>(int left, const Rational &right) {
+	return right < left;
+}
+
+bool operator<(int left, const Rational &right) {
+	return right > left;
+}
+
+bool operator>=(int left, const Rational &right) {
+	return right <= left;
+}
+
+bool operator<=(int left, const Rational &right) {
+	return right >= left;
+}
+
+} // End of namespace Common