/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- * * ***** BEGIN LICENSE BLOCK ***** * Version: MPL 1.1/GPL 2.0/LGPL 2.1 * * The contents of this file are subject to the Mozilla Public License Version * 1.1 (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * http://www.mozilla.org/MPL/ * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. * * The Original Code is mozilla.org code. * * The Initial Developer of the Original Code is * Netscape Communications Corporation. * Portions created by the Initial Developer are Copyright (C) 1999 * the Initial Developer. All Rights Reserved. * * Contributor(s): * * Alternatively, the contents of this file may be used under the terms of * either the GNU General Public License Version 2 or later (the "GPL"), or * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), * in which case the provisions of the GPL or the LGPL are applicable instead * of those above. If you wish to allow use of your version of this file only * under the terms of either the GPL or the LGPL, and not to allow others to * use your version of this file under the terms of the MPL, indicate your * decision by deleting the provisions above and replace them with the notice * and other provisions required by the GPL or the LGPL. If you do not delete * the provisions above, a recipient may use your version of this file under * the terms of any one of the MPL, the GPL or the LGPL. * * ***** END LICENSE BLOCK ***** */ package org.ietf.ldap.ber.stream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; /** * This class is for the Real object. *

See CCITT X.209. * * 

 * ENCODING RULE:
 *  tag    = 0x09
 *
* * @version 1.0 */ public class BERReal extends BERElement { /** * Constants: special ASN.1 real values */ public final static float PLUS_INFINITY = 1.0f/0.0f; public final static float MINUS_INFINITY = -1.0f/0.0f; /** * Value of element */ private float m_value = 0; /** * Constructs a real element with a value * @param value float value */ public BERReal(float value) { m_value = value; } /** * Constructs a real element from an input stream. * @param stream source * @param bytes_read array of 1 int; value incremented by * number of bytes read from stream. * @exception IOException failed to construct */ public BERReal(InputStream stream, int[] bytes_read) throws IOException { int length = super.readLengthOctets(stream, bytes_read); if (length == 0) /* zero length indicates value is zero */ m_value = 0; else { int octet = stream.read(); /* first content octet */ bytes_read[0]++; if (octet == 0x40) /* bit 8 = 1 */ m_value = PLUS_INFINITY; else if (octet == 0x41) /* bit 8 = 1 and bit 1 = 1 */ m_value = MINUS_INFINITY; else if ((octet & 0x80) > 0) { /* bit 8 = 1 */ /* Binary encoding */ /* M = S*N*2F where S = -1 or 1, 0<= F <= 3. */ int sign; int base; int number; int f; /* binary scaling factor */ int exponent; int mantissa; int num_exponent_octets; int contents_length_left; if ((octet & 0x40) > 0) sign = -1; else sign = 1; if ((octet & 0x20) > 0) { if ((octet & 0x10) > 0) { /* bits 6+5 = 11 */ /* reserved for future use */ base = 0; } else { /* bits 6+5 = 10 */ base = 16; } } else if ((octet & 0x10) > 0) { /* bits 6+5 = 01 */ base = 8; } else { /* bits 6+5 = 00 */ base = 2; } if ((octet & 0x08) > 0) { if ((octet & 0x04) > 0) { /* bits 4+3 = 11 */ f = 3; } else { /* bits 4+3 = 10 */ f = 2; } } else if ((octet & 0x04) > 0) { /* bits 4+3 = 01 */ f = 1; } else { /* bits 4+3 = 00 */ f = 0; } if ((octet & 0x02) > 0) { if ((octet & 0x01) > 0) { /* bits 2+1 = 11 */ /* Following octet encodes the number of octets used to * encode the exponent. */ num_exponent_octets = stream.read(); bytes_read[0]++; exponent = readTwosComplement(stream,bytes_read,num_exponent_octets); } else { /* bits 2+1 = 10 */ num_exponent_octets = 3; exponent = readTwosComplement(stream,bytes_read,num_exponent_octets); } } else if ((octet & 0x01) > 0) { /* bits 2+1 = 01 */ num_exponent_octets = 2; exponent = readTwosComplement(stream,bytes_read,num_exponent_octets); } else { /* bits 2+1 = 00 */ num_exponent_octets = 1; exponent = readTwosComplement(stream,bytes_read,num_exponent_octets); } contents_length_left = length - 1 - num_exponent_octets; number = readUnsignedBinary(stream, bytes_read, contents_length_left); mantissa = (int)(sign * number * Math.pow(2, f)); m_value = mantissa * (float)Math.pow(base,exponent); } else { /* bits 8 + 7 = 00 */ /* ISO 6093 field */ /*** NOTE: It has been agreed that this feature will * not be provided right now. */ throw new IOException("real ISO6093 not supported. "); } } } /** * Sends the BER encoding directly to a stream. * @param stream output stream * @exception IOException failed to write */ public void write(OutputStream stream) throws IOException { if (m_value == 0) { stream.write(BERElement.REAL); stream.write(0x00); /* length */ } else if (m_value == PLUS_INFINITY) { stream.write(BERElement.REAL); stream.write(0x01); /* length */ stream.write(0x40); /* contents */ } else if (m_value == MINUS_INFINITY) { stream.write(BERElement.REAL); stream.write(0x01); /* length */ stream.write(0x41); /* contents */ } else { /* Non-special real value */ /* NOTE: currently always sends as a base 2 binary encoding * (see X.2 09 section 10.5.) * * M = S * N * 2F * * Simple encoding always uses F = 1. */ // bcm - incomplete. } } /** * Gets the element type. * @return element type */ public int getType() { return BERElement.REAL; } /** * Gets the string representation. * @return string representation of tag */ public String toString() { return "Real {" + m_value + "}"; } }