package org.caudexorigo.io;
import java.io.IOException;
import java.io.InputStream;
/**
* A <code>ByteArrayInputStream</code> contains an internal buffer that contains bytes that may be read from the stream. An internal counter keeps track of the next byte to be supplied by the <code>read</code> method.
* <p>
* Closing a <tt>ByteArrayInputStream</tt> has no effect. The methods in this class can be called after the stream has been closed without generating an <tt>IOException</tt>.
*
*/
public class UnsynchronizedByteArrayInputStream extends InputStream
{
/**
* An array of bytes that was provided by the creator of the stream. Elements <code>buf[0]</code> through <code>buf[count-1]</code> are the only bytes that can ever be read from the stream; element <code>buf[pos]</code> is the next byte to be read.
*/
protected byte buf[];
/**
* The index of the next character to read from the input stream buffer. This value should always be nonnegative and not larger than the value of <code>count</code>. The next byte to be read from the input stream buffer will be <code>buf[pos]</code>.
*/
protected int pos;
/**
* The currently marked position in the stream. ByteArrayInputStream objects are marked at position zero by default when constructed. They may be marked at another position within the buffer by the <code>mark()</code> method. The current buffer position is set to this point by the <code>reset()</code> method.
* <p>
* If no mark has been set, then the value of mark is the offset passed to the constructor (or 0 if the offset was not supplied).
*
* @since JDK1.1
*/
protected int mark = 0;
/**
* The index one greater than the last valid character in the input stream buffer. This value should always be nonnegative and not larger than the length of <code>buf</code>. It is one greater than the position of the last byte within <code>buf</code> that can ever be read from the input stream buffer.
*/
protected int count;
/**
* Creates a <code>ByteArrayInputStream</code> so that it uses <code>buf</code> as its buffer array. The buffer array is not copied. The initial value of <code>pos</code> is <code>0</code> and the initial value of <code>count</code> is the length of <code>buf</code>.
*
* @param buf
* the input buffer.
*/
public UnsynchronizedByteArrayInputStream(byte buf[])
{
this.buf = buf;
this.pos = 0;
this.count = buf.length;
}
/**
* Creates <code>ByteArrayInputStream</code> that uses <code>buf</code> as its buffer array. The initial value of <code>pos</code> is <code>offset</code> and the initial value of <code>count</code> is the minimum of <code>offset+length</code> and <code>buf.length</code>. The buffer array is not copied. The buffer's mark is set to the specified offset.
*
* @param buf
* the input buffer.
* @param offset
* the offset in the buffer of the first byte to read.
* @param length
* the maximum number of bytes to read from the buffer.
*/
public UnsynchronizedByteArrayInputStream(byte buf[], int offset, int length)
{
this.buf = buf;
this.pos = offset;
this.count = Math.min(offset + length, buf.length);
this.mark = offset;
}
/**
* Reads the next byte of data from this input stream. The value byte is returned as an <code>int</code> in the range <code>0</code> to <code>255</code>. If no byte is available because the end of the stream has been reached, the value <code>-1</code> is returned.
* <p>
* This <code>read</code> method cannot block.
*
* @return the next byte of data, or <code>-1</code> if the end of the stream has been reached.
*/
public int read()
{
return (pos < count) ? (buf[pos++] & 0xff) : -1;
}
/**
* Reads up to <code>len</code> bytes of data into an array of bytes from this input stream. If <code>pos</code> equals <code>count</code>, then <code>-1</code> is returned to indicate end of file. Otherwise, the number <code>k</code> of bytes read is equal to the smaller of <code>len</code> and <code>count-pos</code>. If <code>k</code> is positive, then bytes <code>buf[pos]</code> through <code>buf[pos+k-1]</code> are copied into <code>b[off]</code> through <code>b[off+k-1]</code> in the manner performed by <code>System.arraycopy</code>. The value <code>k</code> is added into <code>pos</code> and <code>k</code> is returned.
* <p>
* This <code>read</code> method cannot block.
*
* @param b
* the buffer into which the data is read.
* @param off
* the start offset in the destination array <code>b</code>
* @param len
* the maximum number of bytes read.
* @return the total number of bytes read into the buffer, or <code>-1</code> if there is no more data because the end of the stream has been reached.
* @exception NullPointerException
* If <code>b</code> is <code>null</code>.
* @exception IndexOutOfBoundsException
* If <code>off</code> is negative, <code>len</code> is negative, or <code>len</code> is greater than <code>b.length - off</code>
*/
public int read(byte b[], int off, int len)
{
if (b == null)
{
throw new NullPointerException();
}
else if (off < 0 || len < 0 || len > b.length - off)
{
throw new IndexOutOfBoundsException();
}
if (pos >= count)
{
return -1;
}
if (pos + len > count)
{
len = count - pos;
}
if (len <= 0)
{
return 0;
}
System.arraycopy(buf, pos, b, off, len);
pos += len;
return len;
}
/**
* Skips <code>n</code> bytes of input from this input stream. Fewer bytes might be skipped if the end of the input stream is reached. The actual number <code>k</code> of bytes to be skipped is equal to the smaller of <code>n</code> and <code>count-pos</code>. The value <code>k</code> is added into <code>pos</code> and <code>k</code> is returned.
*
* @param n
* the number of bytes to be skipped.
* @return the actual number of bytes skipped.
*/
public long skip(long n)
{
if (pos + n > count)
{
n = count - pos;
}
if (n < 0)
{
return 0;
}
pos += n;
return n;
}
/**
* Returns the number of remaining bytes that can be read (or skipped over) from this input stream.
* <p>
* The value returned is <code>count - pos</code>, which is the number of bytes remaining to be read from the input buffer.
*
* @return the number of remaining bytes that can be read (or skipped over) from this input stream without blocking.
*/
public int available()
{
return count - pos;
}
/**
* Tests if this <code>InputStream</code> supports mark/reset. The <code>markSupported</code> method of <code>ByteArrayInputStream</code> always returns <code>true</code>.
*
* @since JDK1.1
*/
public boolean markSupported()
{
return true;
}
/**
* Set the current marked position in the stream. ByteArrayInputStream objects are marked at position zero by default when constructed. They may be marked at another position within the buffer by this method.
* <p>
* If no mark has been set, then the value of the mark is the offset passed to the constructor (or 0 if the offset was not supplied).
*
* <p>
* Note: The <code>readAheadLimit</code> for this class has no meaning.
*
* @since JDK1.1
*/
public void mark(int readAheadLimit)
{
mark = pos;
}
/**
* Resets the buffer to the marked position. The marked position is 0 unless another position was marked or an offset was specified in the constructor.
*/
public void reset()
{
pos = mark;
}
/**
* Closing a <tt>ByteArrayInputStream</tt> has no effect. The methods in this class can be called after the stream has been closed without generating an <tt>IOException</tt>.
* <p>
*/
public void close() throws IOException
{
}
}