3 files changed, 59 insertions, 25 deletions

diff --git a/common/algorithm.h b/common/algorithm.h
index 06f2a279af..d3f518b225 100644
--- a/common/algorithm.h
+++ b/common/algorithm.h
@@ -227,6 +227,8 @@ void sort(T first, T last) {
  */
 template<class T>
 T gcd(T a, T b) {
+	if (a <= 0) a = -a;
+	if (b <= 0) b = -b;
 	while (a > 0) {
 		T tmp = a;
 		a = b % a;
diff --git a/common/rational.cpp b/common/rational.cpp
index e27e880a04..91d1c5a848 100644
--- a/common/rational.cpp
+++ b/common/rational.cpp
@@ -49,7 +49,7 @@ Rational::Rational(int num, int denom) {
 
 void Rational::cancel() {
 	// Cancel the fraction by dividing both the num and the denom
-	// by their greatest common denom.
+	// by their greatest common divisor.
 
 	int gcd = Common::gcd(_num, _denom);
 
@@ -144,65 +144,49 @@ const Rational Rational::operator-() const {
 
 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;
 }
 
@@ -296,33 +280,25 @@ Rational::operator double() const {
 
 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;
 }
 
diff --git a/test/common/rational.h b/test/common/rational.h
index f1a4ea6ab2..5425ec4d81 100644
--- a/test/common/rational.h
+++ b/test/common/rational.h
@@ -35,4 +35,60 @@ public:
 		TS_ASSERT(!(7 >  r4));
 		TS_ASSERT(!(7 >= r4));
 	}
+
+	void test_assign() {
+		Common::Rational r0(6, 3);
+		Common::Rational r1(1, 2);
+
+		TS_ASSERT(r0 == 2);
+		TS_ASSERT(r1 == Common::Rational(1, 2));
+
+		r0 = r1;
+		TS_ASSERT(r0 == r1);
+		TS_ASSERT(r0 == Common::Rational(1, 2));
+	}
+
+	void test_negative() {
+		Common::Rational r0(6, 3);
+		Common::Rational r1(1, 2);
+
+		r0 = -r0;
+		r1 = -r1;
+		TS_ASSERT(r0 == -2);
+		TS_ASSERT(r1 == Common::Rational(-1, 2));
+		TS_ASSERT(r1 == Common::Rational(1, -2));
+	}
+
+	void test_add_sub() {
+		const Common::Rational r0(6, 3);
+		const Common::Rational r1(1, 2);
+
+		TS_ASSERT(r0 + r1 == Common::Rational(5, 2));
+		TS_ASSERT(r1 + r0 == Common::Rational(5, 2));
+		TS_ASSERT(r0 - r1 == Common::Rational(3, 2));
+		TS_ASSERT(r1 - r0 == Common::Rational(-3, 2));
+	}
+
+	void test_mul() {
+		const Common::Rational r0(6, 3);
+		const Common::Rational r1(1, 2);
+
+		const Common::Rational r2(15, 14);
+		const Common::Rational r3(7,3);
+		const Common::Rational r4(5,2);
+
+		TS_ASSERT_EQUALS(r0 * r1, 1);
+
+		TS_ASSERT_EQUALS(r2 * r3, r4);
+		TS_ASSERT_EQUALS((-r2) * r3, -r4);
+		TS_ASSERT_EQUALS(r2 * (-r3), -r4);
+		TS_ASSERT_EQUALS((-r2) * (-r3), r4);
+	}
+
+	void test_div() {
+		Common::Rational r0(6, 3);
+		Common::Rational r1(1, 2);
+
+		TS_ASSERT(r0 / r1 == 4);
+	}
 };