001    /*
002     *  Licensed to the Apache Software Foundation (ASF) under one
003     *  or more contributor license agreements.  See the NOTICE file
004     *  distributed with this work for additional information
005     *  regarding copyright ownership.  The ASF licenses this file
006     *  to you under the Apache License, Version 2.0 (the
007     *  "License"); you may not use this file except in compliance
008     *  with the License.  You may obtain a copy of the License at
009     *  
010     *    http://www.apache.org/licenses/LICENSE-2.0
011     *  
012     *  Unless required by applicable law or agreed to in writing,
013     *  software distributed under the License is distributed on an
014     *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     *  KIND, either express or implied.  See the License for the
016     *  specific language governing permissions and limitations
017     *  under the License. 
018     *  
019     */
020    package org.apache.directory.shared.asn1.util;
021    
022    
023    import org.apache.directory.shared.asn1.ber.tlv.Value;
024    import org.apache.directory.shared.i18n.I18n;
025    
026    
027    /**
028     * Parse and decode an Integer value.
029     * 
030     * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
031     * @version $Rev: 912399 $, $Date: 2010-02-21 21:52:31 +0100 (Sun, 21 Feb 2010) $
032     */
033    public class IntegerDecoder
034    {
035        private static final int[] MASK = new int[]
036            { 0x000000FF, 0x0000FFFF, 0x00FFFFFF, 0xFFFFFFFF };
037    
038    
039        // ~ Methods
040        // ------------------------------------------------------------------------------------
041    
042        /**
043         * Parse a byte buffer and send back an integer, controling that this number
044         * is in a specified interval.
045         * 
046         * @param value
047         *            The byte buffer to parse
048         * @param min
049         *            Lowest value allowed, included
050         * @param max
051         *            Highest value allowed, included
052         * @return An integer
053         * @throws IntegerDecoderException
054         *             Thrown if the byte stream does not contains an integer
055         */
056        public static int parse( Value value, int min, int max ) throws IntegerDecoderException
057        {
058    
059            int result = 0;
060    
061            byte[] bytes = value.getData();
062    
063            if ( ( bytes == null ) || ( bytes.length == 0 ) )
064            {
065                throw new IntegerDecoderException( I18n.err( I18n.ERR_00036 ) );
066            }
067    
068            if ( bytes.length > 4 )
069            {
070                throw new IntegerDecoderException( I18n.err( I18n.ERR_00037 ) );
071            }
072    
073            for ( int i = 0; ( i < bytes.length ) && ( i < 5 ); i++ )
074            {
075                result = ( result << 8 ) | ( bytes[i] & 0x00FF );
076            }
077    
078            if ( ( bytes[0] & 0x80 ) == 0x80 )
079            {
080                result = -( ( ( ~result ) + 1 ) & MASK[bytes.length - 1] );
081            }
082    
083            if ( ( result >= min ) && ( result <= max ) )
084            {
085                return result;
086            }
087            else
088            {
089                throw new IntegerDecoderException( I18n.err( I18n.ERR_00038, min, max ) );
090            }
091        }
092    
093    
094        /**
095         * Parse a byte buffer and send back an integer
096         * 
097         * @param value
098         *            The byte buffer to parse
099         * @return An integer
100         * @throws IntegerDecoderException
101         *             Thrown if the byte stream does not contains an integer
102         */
103        public static int parse( Value value ) throws IntegerDecoderException
104        {
105            return parse( value, Integer.MIN_VALUE, Integer.MAX_VALUE );
106        }
107    }