/*
 * Copyright (c) 1999, 2007, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
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 *
 *
 *
 *
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 *
 */

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();
 }

}