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| 1 | +/* | |
| 2 | + * Copyright (c) 1999, 2007, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package java.math; | |
| 27 | + | |
| 28 | +/** | |
| 29 | + * A class used to represent multiprecision integers that makes efficient | |
| 30 | + * use of allocated space by allowing a number to occupy only part of | |
| 31 | + * an array so that the arrays do not have to be reallocated as often. | |
| 32 | + * When performing an operation with many iterations the array used to | |
| 33 | + * hold a number is only increased when necessary and does not have to | |
| 34 | + * be the same size as the number it represents. A mutable number allows | |
| 35 | + * calculations to occur on the same number without having to create | |
| 36 | + * a new number for every step of the calculation as occurs with | |
| 37 | + * BigIntegers. | |
| 38 | + * | |
| 39 | + * Note that SignedMutableBigIntegers only support signed addition and | |
| 40 | + * subtraction. All other operations occur as with MutableBigIntegers. | |
| 41 | + * | |
| 42 | + * @see BigInteger | |
| 43 | + * @author Michael McCloskey | |
| 44 | + * @since 1.3 | |
| 45 | + */ | |
| 46 | + | |
| 47 | +class SignedMutableBigInteger extends MutableBigInteger { | |
| 48 | + | |
| 49 | + /** | |
| 50 | + * The sign of this MutableBigInteger. | |
| 51 | + */ | |
| 52 | + int sign = 1; | |
| 53 | + | |
| 54 | + // Constructors | |
| 55 | + | |
| 56 | + /** | |
| 57 | + * The default constructor. An empty MutableBigInteger is created with | |
| 58 | + * a one word capacity. | |
| 59 | + */ | |
| 60 | + SignedMutableBigInteger() { | |
| 61 | + super(); | |
| 62 | + } | |
| 63 | + | |
| 64 | + /** | |
| 65 | + * Construct a new MutableBigInteger with a magnitude specified by | |
| 66 | + * the int val. | |
| 67 | + */ | |
| 68 | + SignedMutableBigInteger(int val) { | |
| 69 | + super(val); | |
| 70 | + } | |
| 71 | + | |
| 72 | + /** | |
| 73 | + * Construct a new MutableBigInteger with a magnitude equal to the | |
| 74 | + * specified MutableBigInteger. | |
| 75 | + */ | |
| 76 | + SignedMutableBigInteger(MutableBigInteger val) { | |
| 77 | + super(val); | |
| 78 | + } | |
| 79 | + | |
| 80 | + // Arithmetic Operations | |
| 81 | + | |
| 82 | + /** | |
| 83 | + * Signed addition built upon unsigned add and subtract. | |
| 84 | + */ | |
| 85 | + void signedAdd(SignedMutableBigInteger addend) { | |
| 86 | + if (sign == addend.sign) | |
| 87 | + add(addend); | |
| 88 | + else | |
| 89 | + sign = sign * subtract(addend); | |
| 90 | + | |
| 91 | + } | |
| 92 | + | |
| 93 | + /** | |
| 94 | + * Signed addition built upon unsigned add and subtract. | |
| 95 | + */ | |
| 96 | + void signedAdd(MutableBigInteger addend) { | |
| 97 | + if (sign == 1) | |
| 98 | + add(addend); | |
| 99 | + else | |
| 100 | + sign = sign * subtract(addend); | |
| 101 | + | |
| 102 | + } | |
| 103 | + | |
| 104 | + /** | |
| 105 | + * Signed subtraction built upon unsigned add and subtract. | |
| 106 | + */ | |
| 107 | + void signedSubtract(SignedMutableBigInteger addend) { | |
| 108 | + if (sign == addend.sign) | |
| 109 | + sign = sign * subtract(addend); | |
| 110 | + else | |
| 111 | + add(addend); | |
| 112 | + | |
| 113 | + } | |
| 114 | + | |
| 115 | + /** | |
| 116 | + * Signed subtraction built upon unsigned add and subtract. | |
| 117 | + */ | |
| 118 | + void signedSubtract(MutableBigInteger addend) { | |
| 119 | + if (sign == 1) | |
| 120 | + sign = sign * subtract(addend); | |
| 121 | + else | |
| 122 | + add(addend); | |
| 123 | + if (intLen == 0) | |
| 124 | + sign = 1; | |
| 125 | + } | |
| 126 | + | |
| 127 | + /** | |
| 128 | + * Print out the first intLen ints of this MutableBigInteger's value | |
| 129 | + * array starting at offset. | |
| 130 | + */ | |
| 131 | + public String toString() { | |
| 132 | + return this.toBigInteger(sign).toString(); | |
| 133 | + } | |
| 134 | + | |
| 135 | +} | |