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136 lines
3.0 KiB
136 lines
3.0 KiB
/*
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* Copyright (c) 1999, 2007, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*/
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package java.math;
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/**
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* A class used to represent multiprecision integers that makes efficient
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* use of allocated space by allowing a number to occupy only part of
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* an array so that the arrays do not have to be reallocated as often.
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* When performing an operation with many iterations the array used to
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* hold a number is only increased when necessary and does not have to
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* be the same size as the number it represents. A mutable number allows
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* calculations to occur on the same number without having to create
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* a new number for every step of the calculation as occurs with
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* BigIntegers.
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*
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* Note that SignedMutableBigIntegers only support signed addition and
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* subtraction. All other operations occur as with MutableBigIntegers.
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*
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* @see BigInteger
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* @author Michael McCloskey
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* @since 1.3
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*/
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class SignedMutableBigInteger extends MutableBigInteger {
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/**
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* The sign of this MutableBigInteger.
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*/
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int sign = 1;
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// Constructors
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/**
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* The default constructor. An empty MutableBigInteger is created with
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* a one word capacity.
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*/
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SignedMutableBigInteger() {
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super();
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}
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/**
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* Construct a new MutableBigInteger with a magnitude specified by
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* the int val.
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*/
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SignedMutableBigInteger(int val) {
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super(val);
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}
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/**
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* Construct a new MutableBigInteger with a magnitude equal to the
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* specified MutableBigInteger.
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*/
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SignedMutableBigInteger(MutableBigInteger val) {
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super(val);
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}
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// Arithmetic Operations
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/**
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* Signed addition built upon unsigned add and subtract.
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*/
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void signedAdd(SignedMutableBigInteger addend) {
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if (sign == addend.sign)
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add(addend);
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else
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sign = sign * subtract(addend);
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}
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/**
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* Signed addition built upon unsigned add and subtract.
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*/
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void signedAdd(MutableBigInteger addend) {
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if (sign == 1)
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add(addend);
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else
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sign = sign * subtract(addend);
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}
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/**
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* Signed subtraction built upon unsigned add and subtract.
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*/
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void signedSubtract(SignedMutableBigInteger addend) {
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if (sign == addend.sign)
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sign = sign * subtract(addend);
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else
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add(addend);
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}
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/**
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* Signed subtraction built upon unsigned add and subtract.
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*/
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void signedSubtract(MutableBigInteger addend) {
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if (sign == 1)
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sign = sign * subtract(addend);
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else
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add(addend);
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if (intLen == 0)
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sign = 1;
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}
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/**
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* Print out the first intLen ints of this MutableBigInteger's value
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* array starting at offset.
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*/
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public String toString() {
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return this.toBigInteger(sign).toString();
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}
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}
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