/*
* 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();
}
}