asnbitstring.java

ASN.1工具源代码,包括编译源码生成工具和各种基本类型构造类型的编解码实现代码

/**
 *
 * AsnBitString : A utility class representing an ASN bit string
 *
 * @author Ian Ibbotson ( [e-mail] )
 * @version $Id: AsnBitString.java,v 1.2 2000/12/23 10:44:33 ianibbo Exp $
 *
 * Copyright:   Copyright (C) 2000, Knowledge Integration Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1 of
 * the license, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite
 * 330, Boston, MA  02111-1307, USA.
 *
 */

package com.k_int.codec.runtime;

public class AsnBitString
{
    public int numbytes=0;
    public int unused_bits = 0;
    public byte[] value = null;

    public AsnBitString()
    {
      // Default to 8 bits of data, we can always grow later...
      numbytes=1;
      value = new byte[1];
    }

    public AsnBitString(byte[] bits, int unused)
    {
      value = bits;
      unused_bits = unused;
    }

    public AsnBitString(int top_bit_pos)
    {
        // Allocate the value buffer based on the top bit position...
        numbytes = top_bit_pos / 8;
        numbytes += ( top_bit_pos % 8 > 0 ? 1 : 0 );
        value = new byte[numbytes];
    }

    byte[] getValue()
    {
        return value;
    }

    // Set a specific bit position
    public void setBit(int bitpos)
    {
        int num_bytes_needed = (bitpos+1) / 8;
        num_bytes_needed += ( (bitpos+1) % 8 > 0 ? 1 : 0 );

	// System.err.println("setBit request to set bit at pos "+bitpos);
        // System.err.println("setBit num_bytes_needed = "+num_bytes_needed+" current = "+numbytes);

        if ( num_bytes_needed > numbytes )
        {
            // System.err.println("re-allocating bitstring");

            // We need to re-allocate the buffer
            byte [] newvalue = new byte[num_bytes_needed];
            if ( null != value )
                System.arraycopy(value, 0, newvalue, 0, numbytes);

            numbytes = num_bytes_needed;
            value = newvalue;
        }

        // Figure out which octet contains the bit we need to set, and what
        // position in that octet

        int octet_to_set = bitpos / 8;
        int bit_to_set = 7 - ( bitpos % 8 );
        // int bit_to_set = 8 - ( bitpos % 8 );

        value[octet_to_set] |= ( 1 <<  bit_to_set );

        // System.err.println("After anding bit "+bit_to_set+" of octet "+octet_to_set+" with "+(1 <<  bit_to_set)+"value = "+value[octet_to_set]);
    }

    // Check a specific bit position
    public void isBitSet(int bitpos)
    {

    }
}