/*
 
* Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
 
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 
*
 
* This code is free software; you can redistribute it and/or modify it
 
* under the terms of the GNU General Public License version 2 only, as
 
* published by the Free Software Foundation.
  
Oracle designates this
 
* particular file as subject to the "Classpath" exception as provided
 
* by Oracle in the LICENSE file that accompanied this code.
 
*
 
* This code 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 General Public License
 
* version 2 for more details (a copy is included in the LICENSE file that
 
* accompanied this code).
 
*
 
* You should have received a copy of the GNU General Public License version
 
* 2 along with this work; if not, write to the Free Software Foundation,
 
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 
*
 
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 
* or visit www.oracle.com if you need additional information or have any
 
* questions.
 
*/

package java.io;

/**
 
* 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>.
 
*
 
* @author
  
Arthur van Hoff
 
* @see
     
java.io.StringBufferInputStream
 
* @since
   
JDK1.0
 
*/

public
class
ByteArrayInputStream 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
   
bufthe input buffer.
     
*/

    
public ByteArrayInputStream(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
   
offsetthe offset in the buffer of the first byte to read.
     
* @param
   
lengththe maximum number of bytes to read from the buffer.
     
*/

    
public ByteArrayInputStream(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 synchronized 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
   
bthe buffer into which the data is read.
     
* @param
   
offthe start offset in the destination array <code>b</code>
     
* @param
   
lenthe 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 synchronized 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;
        
}

        
int avail = count - pos;
        
if (len > avail) {
            
len = avail;
        
}
        
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
   
nthe number of bytes to be skipped.
     
* @return
  
the actual number of bytes skipped.
     
*/

    
public synchronized long skip(long n) {
        
long k = count - pos;
        
if (n < k) {
            
k = n < 0 ? 0 : n;
        
}

        
pos += k;
        
return k;
    
}

    
/**
     
* Returns the number of remaining bytes that can be read (or skipped over)
     
* from this input stream.
     
* <p>
     
* The value returned is <code>count&nbsp;- 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 synchronized 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 synchronized 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>.
     
*/

    
public void close() throws IOException {
    
}

}