1/*
2 *  Licensed to the Apache Software Foundation (ASF) under one or more
3 *  contributor license agreements.  See the NOTICE file distributed with
4 *  this work for additional information regarding copyright ownership.
5 *  The ASF licenses this file to You under the Apache License, Version 2.0
6 *  (the "License"); you may not use this file except in compliance with
7 *  the License.  You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 *  Unless required by applicable law or agreed to in writing, software
12 *  distributed under the License is distributed on an "AS IS" BASIS,
13 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 *  See the License for the specific language governing permissions and
15 *  limitations under the License.
16 */
17
18/**
19* @author Vladimir N. Molotkov, Stepan M. Mishura
20* @version $Revision$
21*/
22
23package org.apache.harmony.security.asn1;
24
25import java.io.IOException;
26import java.math.BigInteger;
27
28/**
29 * This class represents ASN.1 Integer type.
30 *
31 * @see <a href="http://asn1.elibel.tm.fr/en/standards/index.htm">ASN.1</a>
32 */
33public final class ASN1Integer extends ASN1Primitive {
34
35    /** default implementation */
36    private static final ASN1Integer ASN1 = new ASN1Integer();
37
38    /**
39     * Constructs ASN.1 Integer type
40     *
41     * The constructor is provided for inheritance purposes
42     * when there is a need to create a custom ASN.1 Integer type.
43     * To get a default implementation it is recommended to use
44     * getInstance() method.
45     */
46    public ASN1Integer() {
47        super(TAG_INTEGER);
48    }
49
50    /**
51     * Returns ASN.1 Integer type default implementation
52     *
53     * The default implementation works with encoding
54     * that is represented as byte array in two's-complement notation.
55     *
56     * @return ASN.1 Integer type default implementation
57     */
58    public static ASN1Integer getInstance() {
59        return ASN1;
60    }
61
62    public Object decode(BerInputStream in) throws IOException {
63        in.readInteger();
64
65        if (in.isVerify) {
66            return null;
67        }
68        return getDecodedObject(in);
69    }
70
71    /**
72     * Extracts array of bytes from BER input stream.
73     *
74     * @return array of bytes
75     */
76    public Object getDecodedObject(BerInputStream in) throws IOException {
77        byte[] bytesEncoded = new byte[in.length];
78        System.arraycopy(in.buffer, in.contentOffset, bytesEncoded, 0,
79                in.length);
80        return bytesEncoded;
81    }
82
83    public void encodeContent(BerOutputStream out) {
84        out.encodeInteger();
85    }
86
87    public void setEncodingContent(BerOutputStream out) {
88        out.length = ((byte[]) out.content).length;
89    }
90
91    /**
92     * Converts decoded ASN.1 Integer to int value.
93     * If the object represents an integer value
94     * larger than 32 bits, the high bits will be lost.
95     *
96     * @param decoded a decoded object corresponding to this type
97     * @return decoded int value.
98     */
99    public static int toIntValue(Object decoded) {
100        return new BigInteger((byte[]) decoded).intValue();
101    }
102
103    /**
104     * Converts decoded ASN.1 Integer to a BigInteger.
105     *
106     * @param decoded a decoded object corresponding to this type
107     * @return decoded BigInteger value.
108     */
109    public static BigInteger toBigIntegerValue(Object decoded) {
110        return new BigInteger((byte[]) decoded);
111    }
112
113    /**
114     * Converts primitive int value to a form most suitable for encoding.
115     *
116     * @param value primitive value to be encoded
117     * @return object suitable for encoding
118     */
119    public static Object fromIntValue(int value) {
120        return BigInteger.valueOf(value).toByteArray();
121    }
122}
123