package org.bouncycastle.crypto.tls;
/**
* A queue for bytes. This file could be more optimized.
*/
public class ByteQueue
{
/**
* @return The smallest number which can be written as 2^x which is bigger than i.
*/
public static final int nextTwoPow(int i)
{
/*
* This code is based of a lot of code I found on the Internet which mostly
* referenced a book called "Hacking delight".
*/
i |= (i >> 1);
i |= (i >> 2);
i |= (i >> 4);
i |= (i >> 8);
i |= (i >> 16);
return i + 1;
}
/**
* The initial size for our buffer.
*/
private static final int INITBUFSIZE = 1024;
/**
* The buffer where we store our data.
*/
private byte[] databuf = new byte[ByteQueue.INITBUFSIZE];
/**
* How many bytes at the beginning of the buffer are skipped.
*/
private int skipped = 0;
/**
* How many bytes in the buffer are valid data.
*/
private int available = 0;
/**
* Read data from the buffer.
*
* @param buf The buffer where the read data will be copied to.
* @param offset How many bytes to skip at the beginning of buf.
* @param len How many bytes to read at all.
* @param skip How many bytes from our data to skip.
*/
public void read(byte[] buf, int offset, int len, int skip)
{
if ((available - skip) < len)
{
throw new TlsRuntimeException("Not enough data to read");
}
if ((buf.length - offset) < len)
{
throw new TlsRuntimeException("Buffer size of " + buf.length
+ " is too small for a read of " + len + " bytes");
}
System.arraycopy(databuf, skipped + skip, buf, offset, len);
return;
}
/**
* Add some data to our buffer.
*
* @param data A byte-array to read data from.
* @param offset How many bytes to skip at the beginning of the array.
* @param len How many bytes to read from the array.
*/
public void addData(byte[] data, int offset, int len)
{
if ((skipped + available + len) > databuf.length)
{
byte[] tmp = new byte[ByteQueue.nextTwoPow(data.length)];
System.arraycopy(databuf, skipped, tmp, 0, available);
skipped = 0;
databuf = tmp;
}
System.arraycopy(data, offset, databuf, skipped + available, len);
available += len;
}
/**
* Remove some bytes from our data from the beginning.
*
* @param i How many bytes to remove.
*/
public void removeData(int i)
{
if (i > available)
{
throw new TlsRuntimeException("Cannot remove " + i + " bytes, only got " + available);
}
/*
* Skip the data.
*/
available -= i;
skipped += i;
/*
* If more than half of our data is skipped, we will move the data in the buffer.
*/
if (skipped > (databuf.length / 2))
{
System.arraycopy(databuf, skipped, databuf, 0, available);
skipped = 0;
}
}
/**
* @return The number of bytes which are available in this buffer.
*/
public int size()
{
return available;
}
}