Language Java Nosugar Comms Code Byteswappedrandomaccessfile.java

// 
//	ByteSwappedRandomAccessFile class
//	part of the set of documents known as Java no sugar.
//	Copyright (c) 1996 Sunil Gupta, sunil@magnetic.demon.co.uk
//	placed into the public domain by the author
//
//	integers and shorts work, but floats are buggered
//	java doesnt come with byteswapping code, wot a crying shame.
//
import java.io.*;
import EncapsulatedRandomAccessFile
import ByteSwapper;

public class ByteSwappedRandomAccessFile extends EncapsulatedRandomAccessFile
{		
	public boolean byteSwapping = false;
	
	//############################################################################
	// 			Constructors
	//############################################################################
	public ByteSwappedRandomAccessFile(File file, String mode) throws IOException
	{
		super(file,mode);
	}
	
	//############################################################################
	// 			these need to be byteswapped
	//############################################################################
	public short readShort() throws IOException
	{
		if (byteSwapping)
			return ( ByteSwapper.swapShort(super.readShort()) );
		else
			return (super.readShort() );
	}

	public long readLong() throws IOException
	{
		if (byteSwapping)
			return ( ByteSwapper.swapLong(super.readLong()) );
		else
			return (super.readLong() );
	}

	public int readInt() throws IOException
	{
		if (byteSwapping)
			return( ByteSwapper.swapInt(super.readInt()) );
		else
			return (super.readInt());
	}
	
	public int readUnsignedShort() throws IOException
	{
		if (byteSwapping)
			return ( ByteSwapper.swapShort( (short) super.readUnsignedShort()) );
		else
			return (super.readUnsignedShort() );
	}
	
	public double readDouble() throws IOException 
	{
		//this is wrong but i dont quite know what to do
		return super.readDouble();
	}
	
	public float readFloat() throws IOException 
	{
		short	mantissa,exponent;
		double real_mantissa;

		if (!byteSwapping)
			return ( super.readFloat());
		else
		{
			mantissa  = readShort();
			exponent  = readShort();
			real_mantissa = ((float)mantissa) / 32768.0;		/* 32768.0 is: 2**15 */
			
			return (float) ldexp(real_mantissa,exponent);
		}
	}
	
	public static double ldexp(double x, int n)
	{
		double answer;
		
		answer = x * Math.pow(2.0, n);
		
		return answer;
	}
	
}

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