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package com.lowagie.bc.asn1;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
public class DERBitString
extends DERObject
implements DERString
{
private static final char[] table = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
protected byte[] data;
protected int padBits;
/**
* return the correct number of pad bits for a bit string defined in
* a 32 bit constant
*/
static protected int getPadBits(
int bitString)
{
int val = 0;
for (int i = 3; i >= 0; i--)
{
//
// this may look a little odd, but if it isn't done like this pre jdk1.2
// JVM's break!
//
if (i != 0)
{
if ((bitString >> (i * 8)) != 0)
{
val = (bitString >> (i * 8)) & 0xFF;
break;
}
}
else
{
if (bitString != 0)
{
val = bitString & 0xFF;
break;
}
}
}
if (val == 0)
{
return 7;
}
int bits = 1;
while (((val <<= 1) & 0xFF) != 0)
{
bits++;
}
return 8 - bits;
}
/**
* return the correct number of bytes for a bit string defined in
* a 32 bit constant
*/
static protected byte[] getBytes(int bitString)
{
int bytes = 4;
for (int i = 3; i >= 1; i--)
{
if ((bitString & (0xFF << (i * 8))) != 0)
{
break;
}
bytes--;
}
byte[] result = new byte[bytes];
for (int i = 0; i < bytes; i++)
{
result[i] = (byte) ((bitString >> (i * 8)) & 0xFF);
}
return result;
}
/**
* return a Bit String from the passed in object
*
* @exception IllegalArgumentException if the object cannot be converted.
*/
public static DERBitString getInstance(
Object obj)
{
if (obj == null || obj instanceof DERBitString)
{
return (DERBitString)obj;
}
if (obj instanceof ASN1OctetString)
{
byte[] bytes = ((ASN1OctetString)obj).getOctets();
int padBits = bytes[0];
byte[] data = new byte[bytes.length - 1];
System.arraycopy(bytes, 1, data, 0, bytes.length - 1);
return new DERBitString(data, padBits);
}
if (obj instanceof ASN1TaggedObject)
{
return getInstance(((ASN1TaggedObject)obj).getObject());
}
throw new IllegalArgumentException("illegal object in getInstance: " + obj.getClass().getName());
}
/**
* return a Bit String from a tagged object.
*
* @param obj the tagged object holding the object we want
* @param explicit true if the object is meant to be explicitly
* tagged false otherwise.
* @exception IllegalArgumentException if the tagged object cannot
* be converted.
*/
public static DERBitString getInstance(
ASN1TaggedObject obj,
boolean explicit)
{
return getInstance(obj.getObject());
}
protected DERBitString(
byte data,
int padBits)
{
this.data = new byte[1];
this.data[0] = data;
this.padBits = padBits;
}
/**
* @param data the octets making up the bit string.
* @param padBits the number of extra bits at the end of the string.
*/
public DERBitString(
byte[] data,
int padBits)
{
this.data = data;
this.padBits = padBits;
}
public DERBitString(
byte[] data)
{
this(data, 0);
}
public DERBitString(
DEREncodable obj)
{
try
{
ByteArrayOutputStream bOut = new ByteArrayOutputStream();
DEROutputStream dOut = new DEROutputStream(bOut);
dOut.writeObject(obj);
dOut.close();
this.data = bOut.toByteArray();
this.padBits = 0;
}
catch (IOException e)
{
throw new IllegalArgumentException("Error processing object : " + e.toString());
}
}
public byte[] getBytes()
{
return data;
}
public int getPadBits()
{
return padBits;
}
void encode(
DEROutputStream out)
throws IOException
{
byte[] bytes = new byte[getBytes().length + 1];
bytes[0] = (byte)getPadBits();
System.arraycopy(getBytes(), 0, bytes, 1, bytes.length - 1);
out.writeEncoded(BIT_STRING, bytes);
}
public int hashCode()
{
int value = 0;
for (int i = 0; i != data.length; i++)
{
value ^= (data[i] & 0xff) << (i % 4);
}
return value;
}
public boolean equals(
Object o)
{
if (o == null || !(o instanceof DERBitString))
{
return false;
}
DERBitString other = (DERBitString)o;
if (data.length != other.data.length)
{
return false;
}
for (int i = 0; i != data.length; i++)
{
if (data[i] != other.data[i])
{
return false;
}
}
return (padBits == other.padBits);
}
public String getString()
{
StringBuffer buf = new StringBuffer("#");
ByteArrayOutputStream bOut = new ByteArrayOutputStream();
ASN1OutputStream aOut = new ASN1OutputStream(bOut);
try
{
aOut.writeObject(this);
}
catch (IOException e)
{
throw new RuntimeException("internal error encoding BitString");
}
byte[] string = bOut.toByteArray();
for (int i = 0; i != string.length; i++)
{
buf.append(table[(string[i] >>> 4) % 0xf]);
buf.append(table[string[i] & 0xf]);
}
return buf.toString();
}
}
