org.jpedal.jbig2.io.StreamReader Maven / Gradle / Ivy

/**
 * ===========================================
 * Java Pdf Extraction Decoding Access Library
 * ===========================================
 * 
 * Project Info:  http://www.jpedal.org
 * (C) Copyright 1997-2008, IDRsolutions and Contributors.
 * Main Developer: Simon Barnett
 * 

 * This file is part of JPedal
 * 

 * Copyright (c) 2008, IDRsolutions
 * All rights reserved.
 * 

 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * * Neither the name of the IDRsolutions nor the
 * names of its contributors may be used to endorse or promote products
 * derived from this software without specific prior written permission.
 * 

 * THIS SOFTWARE IS PROVIDED BY IDRsolutions ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL IDRsolutions BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 

 * Other JBIG2 image decoding implementations include
 * jbig2dec (http://jbig2dec.sourceforge.net/)
 * xpdf (http://www.foolabs.com/xpdf/)
 * 

 * The final draft JBIG2 specification can be found at http://www.jpeg.org/public/fcd14492.pdf
 * 

 * All three of the above resources were used in the writing of this software, with methodologies,
 * processes and inspiration taken from all three.
 * 
 * ---------------
 * StreamReader.java
 * ---------------
 */
package org.jpedal.jbig2.io;

import java.io.IOException;

import org.jpedal.jbig2.examples.pdf.PDFSegment;

public class StreamReader {
    private byte[] data;

    private int bitPointer = 7;

    private int bytePointer = 0;

    public StreamReader(final byte[] data) {
        this.data = data;
    }

    public short readByte(PDFSegment pdfSeg) {
        short bite = (short) (data[bytePointer++] & 255);

        if (pdfSeg != null)
            pdfSeg.writeToHeader(bite);

        return bite;
    }

    public void readByte(short[] buf, PDFSegment pdfSeg) throws IOException {
        for (int i = 0; i < buf.length; i++) {
            buf[i] = (short) (data[bytePointer++] & 255);
        }

        if (pdfSeg != null)
            pdfSeg.writeToHeader(buf);
    }

    public short readByte() {
        short bite = (short) (data[bytePointer++] & 255);

        return bite;
    }

    public void readByte(short[] buf) {
        for (int i = 0; i < buf.length; i++) {
            buf[i] = (short) (data[bytePointer++] & 255);
        }
    }

    public int readBit() {
        short buf = readByte();
        short mask = (short) (1 << bitPointer);

        int bit = (buf & mask) >> bitPointer;

        bitPointer--;
        if (bitPointer == -1) {
            bitPointer = 7;
        } else {
            movePointer(-1);
        }

        return bit;
    }

    public int readBits(int num) {
        int result = 0;

        for (int i = 0; i < num; i++) {
            result = (result << 1) | readBit();
        }

        return result;
    }

    public void movePointer(int ammount) {
        bytePointer += ammount;
    }

    public void consumeRemainingBits() {
        if (bitPointer != 7)
            readBits(bitPointer + 1);
    }

    public boolean isFinished() {
        return bytePointer == data.length;
    }
}