001/*
002 * $RCSfile: ByteOutputBuffer.java,v $
003 * $Revision: 1.1 $
004 * $Date: 2005/02/11 05:02:07 $
005 * $State: Exp $
006 *
007 * Class:                   ByteOutputBuffer
008 *
009 * Description:             Provides buffering for byte based output, similar
010 *                          to the standard class ByteArrayOutputStream
011 *
012 *                          the old jj2000.j2k.io.ByteArrayOutput class by
013 *                          Diego SANTA CRUZ, Apr-26-1999
014 *
015 *
016 * COPYRIGHT:
017 *
018 * This software module was originally developed by Raphaël Grosbois and
019 * Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
020 * Askelöf (Ericsson Radio Systems AB); and Bertrand Berthelot, David
021 * Bouchard, Félix Henry, Gerard Mozelle and Patrice Onno (Canon Research
022 * Centre France S.A) in the course of development of the JPEG2000
023 * standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This
024 * software module is an implementation of a part of the JPEG 2000
025 * Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio
026 * Systems AB and Canon Research Centre France S.A (collectively JJ2000
027 * Partners) agree not to assert against ISO/IEC and users of the JPEG
028 * 2000 Standard (Users) any of their rights under the copyright, not
029 * including other intellectual property rights, for this software module
030 * with respect to the usage by ISO/IEC and Users of this software module
031 * or modifications thereof for use in hardware or software products
032 * claiming conformance to the JPEG 2000 Standard. Those intending to use
033 * this software module in hardware or software products are advised that
034 * their use may infringe existing patents. The original developers of
035 * this software module, JJ2000 Partners and ISO/IEC assume no liability
036 * for use of this software module or modifications thereof. No license
037 * or right to this software module is granted for non JPEG 2000 Standard
038 * conforming products. JJ2000 Partners have full right to use this
039 * software module for his/her own purpose, assign or donate this
040 * software module to any third party and to inhibit third parties from
041 * using this software module for non JPEG 2000 Standard conforming
042 * products. This copyright notice must be included in all copies or
043 * derivative works of this software module.
044 *
045 * Copyright (c) 1999/2000 JJ2000 Partners.
046 *
047 *
048 *
049 */
050
051
052package jj2000.j2k.entropy.encoder;
053
054
055/**
056 * This class provides a buffering output stream similar to
057 * ByteArrayOutputStream, with some additional methods.
058 *
059 * <P>Once an array has been written to an output stream or to a byte
060 * array, the object can be reused as a new stream if the reset()
061 * method is called.
062 *
063 * <P>Unlike the ByteArrayOutputStream class, this class is not thread safe.
064 *
065 * @see #reset
066 * */
067public class ByteOutputBuffer {
068
069    /** The buffer where the data is stored */
070    byte buf[];
071
072    /** The number of valid bytes in the buffer */
073    int count;
074
075    /** The buffer increase size */
076    public final static int BUF_INC = 512;
077
078    /** The default initial buffer size */
079    public final static int BUF_DEF_LEN = 256;
080
081    /**
082     * Creates a new byte array output stream. The buffer capacity is
083     * initially BUF_DEF_LEN bytes, though its size increases if necessary.
084     *
085     *
086     * */
087    public ByteOutputBuffer() {
088        buf = new byte[BUF_DEF_LEN];
089    }
090
091    /**
092     * Creates a new byte array output stream, with a buffer capacity
093     * of the specified size, in bytes.
094     *
095     * @param size the initial size.
096     *
097     *
098     * */
099    public ByteOutputBuffer(int size) {
100        buf = new byte[size];
101    }
102
103    /**
104     * Writes the specified byte to this byte array output stream. The
105     * functionality provided by this implementation is the same as for the
106     * one in the superclass, however this method is not synchronized and
107     * therefore not safe thread, but faster.
108     *
109     * @param b The byte to write
110     *
111     *
112     * */
113    public final void write(int b) {
114        if (count == buf.length) { // Resize buffer
115            byte tmpbuf[] = buf;
116            buf = new byte[buf.length+BUF_INC];
117            System.arraycopy(tmpbuf,0,buf,0,count);
118        }
119        buf[count++] = (byte) b;
120    }
121
122    /**
123     * Copies the specified part of the stream to the 'outbuf' byte
124     * array.
125     *
126     * @param off The index of the first element in the stream to
127     * copy.
128     *
129     * @param len The number of elements of the array to copy
130     *
131     * @param outbuf The destination array
132     *
133     * @param outoff The index of the first element in 'outbuf' where
134     * to write the data.
135     *
136     *
137     * */
138    public void toByteArray(int off, int len, byte outbuf[], int outoff) {
139        // Copy the data
140        System.arraycopy(buf,off,outbuf,outoff,len);
141    }
142
143    /**
144     * Returns the number of valid bytes in the output buffer (count class
145     * variable).
146     *
147     * @return The number of bytes written to the buffer
148     *
149     * */
150    public int size() {
151        return count;
152    }
153
154    /**
155     * Discards all the buffered data, by resetting the counter of written
156     * bytes to 0.
157     *
158     * */
159    public void reset() {
160        count = 0;
161    }
162
163    /**
164     * Returns the byte buffered at the given position in the buffer. The
165     * position in the buffer is the index of the 'write()' method call after
166     * the last call to 'reset()'.
167     *
168     * @param pos The position of the byte to return
169     *
170     * @return The value (betweeb 0-255) of the byte at position 'pos'.
171     *
172     * */
173    public int getByte(int pos) {
174        if (pos >= count) {
175            throw new IllegalArgumentException();
176        }
177        return buf[pos]&0xFF;
178    }
179}