jaroslav@1258: /*
jaroslav@1258:  * Copyright (c) 1999, 2007, Oracle and/or its affiliates. All rights reserved.
jaroslav@1258:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@1258:  *
jaroslav@1258:  * This code is free software; you can redistribute it and/or modify it
jaroslav@1258:  * under the terms of the GNU General Public License version 2 only, as
jaroslav@1258:  * published by the Free Software Foundation.  Oracle designates this
jaroslav@1258:  * particular file as subject to the "Classpath" exception as provided
jaroslav@1258:  * by Oracle in the LICENSE file that accompanied this code.
jaroslav@1258:  *
jaroslav@1258:  * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@1258:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@1258:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jaroslav@1258:  * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@1258:  * accompanied this code).
jaroslav@1258:  *
jaroslav@1258:  * You should have received a copy of the GNU General Public License version
jaroslav@1258:  * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@1258:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@1258:  *
jaroslav@1258:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@1258:  * or visit www.oracle.com if you need additional information or have any
jaroslav@1258:  * questions.
jaroslav@1258:  */
jaroslav@1258: 
jaroslav@1258: package java.math;
jaroslav@1258: 
jaroslav@1258: /**
jaroslav@1258:  * A class used to represent multiprecision integers that makes efficient
jaroslav@1258:  * use of allocated space by allowing a number to occupy only part of
jaroslav@1258:  * an array so that the arrays do not have to be reallocated as often.
jaroslav@1258:  * When performing an operation with many iterations the array used to
jaroslav@1258:  * hold a number is only increased when necessary and does not have to
jaroslav@1258:  * be the same size as the number it represents. A mutable number allows
jaroslav@1258:  * calculations to occur on the same number without having to create
jaroslav@1258:  * a new number for every step of the calculation as occurs with
jaroslav@1258:  * BigIntegers.
jaroslav@1258:  *
jaroslav@1258:  * Note that SignedMutableBigIntegers only support signed addition and
jaroslav@1258:  * subtraction. All other operations occur as with MutableBigIntegers.
jaroslav@1258:  *
jaroslav@1258:  * @see     BigInteger
jaroslav@1258:  * @author  Michael McCloskey
jaroslav@1258:  * @since   1.3
jaroslav@1258:  */
jaroslav@1258: 
jaroslav@1258: class SignedMutableBigInteger extends MutableBigInteger {
jaroslav@1258: 
jaroslav@1258:    /**
jaroslav@1258:      * The sign of this MutableBigInteger.
jaroslav@1258:      */
jaroslav@1258:     int sign = 1;
jaroslav@1258: 
jaroslav@1258:     // Constructors
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * The default constructor. An empty MutableBigInteger is created with
jaroslav@1258:      * a one word capacity.
jaroslav@1258:      */
jaroslav@1258:     SignedMutableBigInteger() {
jaroslav@1258:         super();
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Construct a new MutableBigInteger with a magnitude specified by
jaroslav@1258:      * the int val.
jaroslav@1258:      */
jaroslav@1258:     SignedMutableBigInteger(int val) {
jaroslav@1258:         super(val);
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Construct a new MutableBigInteger with a magnitude equal to the
jaroslav@1258:      * specified MutableBigInteger.
jaroslav@1258:      */
jaroslav@1258:     SignedMutableBigInteger(MutableBigInteger val) {
jaroslav@1258:         super(val);
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:    // Arithmetic Operations
jaroslav@1258: 
jaroslav@1258:    /**
jaroslav@1258:      * Signed addition built upon unsigned add and subtract.
jaroslav@1258:      */
jaroslav@1258:     void signedAdd(SignedMutableBigInteger addend) {
jaroslav@1258:         if (sign == addend.sign)
jaroslav@1258:             add(addend);
jaroslav@1258:         else
jaroslav@1258:             sign = sign * subtract(addend);
jaroslav@1258: 
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:    /**
jaroslav@1258:      * Signed addition built upon unsigned add and subtract.
jaroslav@1258:      */
jaroslav@1258:     void signedAdd(MutableBigInteger addend) {
jaroslav@1258:         if (sign == 1)
jaroslav@1258:             add(addend);
jaroslav@1258:         else
jaroslav@1258:             sign = sign * subtract(addend);
jaroslav@1258: 
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:    /**
jaroslav@1258:      * Signed subtraction built upon unsigned add and subtract.
jaroslav@1258:      */
jaroslav@1258:     void signedSubtract(SignedMutableBigInteger addend) {
jaroslav@1258:         if (sign == addend.sign)
jaroslav@1258:             sign = sign * subtract(addend);
jaroslav@1258:         else
jaroslav@1258:             add(addend);
jaroslav@1258: 
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:    /**
jaroslav@1258:      * Signed subtraction built upon unsigned add and subtract.
jaroslav@1258:      */
jaroslav@1258:     void signedSubtract(MutableBigInteger addend) {
jaroslav@1258:         if (sign == 1)
jaroslav@1258:             sign = sign * subtract(addend);
jaroslav@1258:         else
jaroslav@1258:             add(addend);
jaroslav@1258:         if (intLen == 0)
jaroslav@1258:              sign = 1;
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Print out the first intLen ints of this MutableBigInteger's value
jaroslav@1258:      * array starting at offset.
jaroslav@1258:      */
jaroslav@1258:     public String toString() {
jaroslav@1258:         return this.toBigInteger(sign).toString();
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258: }