From 3ef8a09e20d8ab33d3b87d63be0ffa2c34fb427a Mon Sep 17 00:00:00 2001
From: rubidium <rubidium@openttd.org>
Date: Sat, 21 Mar 2009 01:34:31 +0000
Subject: (svn r15777) -Add: helper functions to get the least common multiple
 and the greatest common divisor (Alberth)

---
 src/core/math_func.cpp | 41 +++++++++++++++++++++++++++++++++++++++++
 src/core/math_func.hpp |  3 +++
 2 files changed, 44 insertions(+)
 create mode 100644 src/core/math_func.cpp

(limited to 'src/core')

diff --git a/src/core/math_func.cpp b/src/core/math_func.cpp
new file mode 100644
index 000000000..360ec0ec5
--- /dev/null
+++ b/src/core/math_func.cpp
@@ -0,0 +1,41 @@
+/* $Id$ */
+
+/** @file math_func.cpp Math functions. */
+
+#include "../stdafx.h"
+#include "math_func.hpp"
+
+/**
+ * Compute least common multiple (lcm) of arguments \a a and \a b, the smallest
+ * integer value that is a multiple of both \a a and \a b.
+ * @param a First number.
+ * @param b second number.
+ * @return Least common multiple of values \a a and \a b.
+ *
+ * @note This function only works for non-negative values of \a a and \a b.
+ */
+int LeastCommonMultiple(int a, int b)
+{
+	if (a == 0 || b == 0) return 0; // By definition.
+	if (a == 1 || a == b) return b;
+	if (b == 1) return a;
+
+	return a * b / GreatestCommonDivisor(a, b);
+}
+
+/**
+ * Compute greatest common divisor (gcd) of \a a and \a b.
+ * @param a First number.
+ * @param b second number.
+ * @return Greatest common divisor of \a a and \a b.
+ */
+int GreatestCommonDivisor(int a, int b)
+{
+	while (b != 0) {
+		int t = b;
+		b = a % b;
+		a = t;
+	}
+	return a;
+
+}
diff --git a/src/core/math_func.hpp b/src/core/math_func.hpp
index 6a0f5c17a..35e660d88 100644
--- a/src/core/math_func.hpp
+++ b/src/core/math_func.hpp
@@ -264,4 +264,7 @@ static FORCEINLINE void Swap(T &a, T &b)
 	b = t;
 }
 
+int LeastCommonMultiple(int a, int b);
+int GreatestCommonDivisor(int a, int b);
+
 #endif /* MATH_FUNC_HPP */
-- 
cgit v1.2.3-54-g00ecf