IntReader.java

package com.github.nukc.plugin.axml.decode;

import java.io.BufferedInputStream;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;

/**
 * @author Dmitry Skiba
 *
 * Simple helper class that allows reading of integers.
 */
public final class IntReader {
	    
	    public IntReader() {
	    }
	    public IntReader(InputStream stream,boolean bigEndian) {
	            reset(stream,bigEndian);
	    }
	    
	    public final void reset(InputStream stream,boolean bigEndian) {
	            m_stream= new BufferedInputStream(stream);
	            m_bigEndian=bigEndian;
	            m_position=0;           
	    }
	
	    public final void close() {
	            if (m_stream==null) {
	                    return;
	            }
	            try {
	                    m_stream.close();
	            }
	            catch (IOException e) {
	            }
	            reset(null,false);
	    }
	    
	    public final InputStream getStream() {
	            return m_stream;
	    }
	    
	    public final boolean isBigEndian() {
	            return m_bigEndian;
	    }
	    public final void setBigEndian(boolean bigEndian) {
	            m_bigEndian=bigEndian;
	    }
	
	    public final int readByte() throws IOException {
	            return readInt(1);
	    }
	    public final int readShort() throws IOException {
	            return readInt(2);
	    }
	    public final int readInt() throws IOException {
	            return readInt(4);
	    }
	    
	    public final int readInt(int length) throws IOException {
	            if (length<0 || length>4) {
	                    throw new IllegalArgumentException();
	            }
	            int result=0;
	            if (m_bigEndian) {
	                    for (int i=(length-1)*8;i>=0;i-=8) {
	                            int b=m_stream.read();
	                            if (b==-1) {
	                                    throw new EOFException();
	                            }
	                            m_position+=1;
	                            result|=(b<<i);
	                    }
	            } else {
	                    length*=8;
	                    for (int i=0;i!=length;i+=8) {
	                            int b=m_stream.read();
	                            if (b==-1) {
	                                    throw new EOFException();
	                            }
	                            m_position+=1;
	                            result|=(b<<i);
	                    }
	            }
	            return result;            
	    }
	    
	    public final int[] readIntArray(int length) throws IOException {
	            int[] array=new int[length];
	            readIntArray(array,0,length);
	            return array;
	    }
	   
	    
	    public final void readIntArray(int[] array,int offset,int length) throws IOException {
	            for (;length>0;length-=1) {
	                    array[offset++]=readInt();
	            }
	    }
	    
	    public final byte[] readByteArray(int length) throws IOException {
	            byte[] array=new byte[length];
	            int read=m_stream.read(array);
	            m_position+=read;
	            if (read!=length) {
	                    throw new EOFException();
	            }
	            return array;
	    }
	    
	    public final void skip(int bytes) throws IOException {
	            if (bytes<=0) {
	                    return;
	            }
	            long skipped=m_stream.skip(bytes);
	            m_position+=skipped;
	            if (skipped!=bytes) {
	                    throw new EOFException();
	            }
	    }
	    
	    public final void skipInt() throws IOException {
	            skip(4);
	    }
	    
	    public final int available() throws IOException {
	            return m_stream.available();
	    }
	    
	    public final int getPosition() {
	            return m_position;
	    }
    
    /////////////////////////////////// data

	private InputStream m_stream;
	private boolean m_bigEndian;
	private int m_position;
}