scummvm/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.
*
*/
#include "common/debug.h"
#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);
if (denom > 0) {
_num = num;
_denom = denom;
} else {
_num = -num;
_denom = -denom;
}
cancel();
}
Rational::Rational(const Rational &rational) {
_num = rational._num;
_denom = rational._denom;
}
void Rational::cancel() {
// Cancel the fraction by dividing both the num and the denom
// by their greatest common divisor.
const int gcd = Common::gcd(_num, _denom);
_num /= gcd;
_denom /= gcd;
}
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) {
// Cancel common factors to avoid unnecessary overflow.
// Note that the result is *not* always normalized.
const int gcd = Common::gcd(_denom, right._denom);
_num = _num * (right._denom / gcd);
_denom = _denom / gcd;
_num += right._num * _denom;
_denom *= right._denom;
cancel();
return *this;
}
Rational &Rational::operator-=(const Rational &right) {
// Cancel common factors to avoid unnecessary overflow.
// Note that the result is *not* always normalized.
const int gcd = Common::gcd(_denom, right._denom);
_num = _num * (right._denom / gcd);
_denom = _denom / gcd;
_num -= right._num * _denom;
_denom *= right._denom;
cancel();
return *this;
}
Rational &Rational::operator*=(const Rational &right) {
// Cross-cancel to avoid unnecessary overflow;
// the result then is automatically normalized
const int gcd1 = gcd(_num, right._denom);
const int gcd2 = gcd(right._num, _denom);
_num = (_num / gcd1) * (right._num / gcd2);
_denom = (_denom / gcd2) * (right._denom / gcd1);
return *this;
}
Rational &Rational::operator/=(const Rational &right) {
return *this *= right.getInverse();
}
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);
if (_denom < 0) {
_denom = -_denom;
_num = -_num;
}
}
Rational Rational::getInverse() const {
Rational inverse = *this;
inverse.invert();
return inverse;
}
int Rational::toInt() const {
return _num / _denom;
}
double Rational::toDouble() const {
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return ((double)_num) / ((double)_denom);
}
frac_t Rational::toFrac() const {
return (_num * FRAC_ONE) / _denom;
}
const Rational operator+(int left, const Rational &right) {
Rational tmp(left);
tmp += right;
return tmp;
}
const Rational operator-(int left, const Rational &right) {
Rational tmp(left);
tmp -= right;
return tmp;
}
const Rational operator*(int left, const Rational &right) {
Rational tmp(left);
tmp *= right;
return tmp;
}
const Rational operator/(int left, const Rational &right) {
Rational tmp(left);
tmp /= right;
return tmp;
}
void Rational::debugPrint(int debuglevel, const char *caption) const {
debug(debuglevel, "%s %d/%d", caption, _num, _denom);
}
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