/*

  * Copyright (c) 1994, 2010, 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

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 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   buf   the 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   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 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   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 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;

         }

         PushbackInputStream.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 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>.

      * <p>

      */

     public void close() throws IOException {

     }

 }