/*
* @(#)SignedMutableBigInteger.java 1.14 06/10/17
*
* Copyright 1990-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 only, as published by the Free Software Foundation.
*
* 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 version 2 for more details (a copy is
* included at /legal/license.txt).
*
* You should have received a copy of the GNU General Public License
* version 2 along with this work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*/
package java.math;
/**
* A class used to represent multiprecision integers that makes efficient
* use of allocated space by allowing a number to occupy only part of
* an array so that the arrays do not have to be reallocated as often.
* When performing an operation with many iterations the array used to
* hold a number is only increased when necessary and does not have to
* be the same size as the number it represents. A mutable number allows
* calculations to occur on the same number without having to create
* a new number for every step of the calculation as occurs with
* BigIntegers.
*
* Note that SignedMutableBigIntegers only support signed addition and
* subtraction. All other operations occur as with MutableBigIntegers.
*
* @see BigInteger
* @version 1.6, 02/02/00
* @author Michael McCloskey
* @since 1.3
*/
class SignedMutableBigInteger extends MutableBigInteger {
/**
* The sign of this MutableBigInteger.
*/
int sign = 1;
// Constructors
/**
* The default constructor. An empty MutableBigInteger is created with
* a one word capacity.
*/
SignedMutableBigInteger() {
super();
}
/**
* Construct a new MutableBigInteger with a magnitude specified by
* the int val.
*/
SignedMutableBigInteger(int val) {
super(val);
}
/**
* Construct a new MutableBigInteger with a magnitude equal to the
* specified MutableBigInteger.
*/
SignedMutableBigInteger(MutableBigInteger val) {
super(val);
}
// Arithmetic Operations
/**
* Signed addition built upon unsigned add and subtract.
*/
void signedAdd(SignedMutableBigInteger addend) {
if (sign == addend.sign)
add(addend);
else
sign = sign * subtract(addend);
}
/**
* Signed addition built upon unsigned add and subtract.
*/
void signedAdd(MutableBigInteger addend) {
if (sign == 1)
add(addend);
else
sign = sign * subtract(addend);
}
/**
* Signed subtraction built upon unsigned add and subtract.
*/
void signedSubtract(SignedMutableBigInteger addend) {
if (sign == addend.sign)
sign = sign * subtract(addend);
else
add(addend);
}
/**
* Signed subtraction built upon unsigned add and subtract.
*/
void signedSubtract(MutableBigInteger addend) {
if (sign == 1)
sign = sign * subtract(addend);
else
add(addend);
if (intLen == 0)
sign = 1;
}
/**
* Print out the first intLen ints of this MutableBigInteger's value
* array starting at offset.
*/
public String toString() {
BigInteger b = new BigInteger(this, sign);
return
b.toString();
}
}