/*

 * Copyright (c) 1999, 2007, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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 in the LICENSE file that

 * accompanied this code).

 *

 * 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.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

 * @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() {

        return this.toBigInteger(sign).toString();

    }

}