OpenTTD/src/core/math_func.cpp

/* $Id$ */

/*
 * This file is part of OpenTTD.
 * OpenTTD 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, version 2.
 * OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @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;

}