fileblockdevice.java

JPC: x86 PC Hardware Emulator. 牛津大学开发的一个纯JAVA的x86系统结构硬件模拟器。

		empty[i]=(byte) 0x00;
	}
	start = new byte[512*95];
	for(int i=1;i<95;i++){
		System.arraycopy(empty,0,start,i*512,512);
	}
	System.arraycopy(MBR,0,start,0,512);
	System.arraycopy(header,0,start,63*512,512);
	System.arraycopy(header2,0,start,64*512,512);
	System.arraycopy(header,0,start,69*512,512);
	System.arraycopy(header2,0,start,70*512,512);
    }

    public void dumpChanges(DataOutput output) throws IOException
    {}

    public void loadChanges(DataInput input) throws IOException
    {}

    //Convert Int to byte[] of certain length
    public static byte[] toByteArray(int n, int l)
    {
	byte[] input = toByteArray(n);
	byte[] answer = new byte[l];
	if(input.length>l)
	    System.arraycopy(input,0,answer,0,l);
	else
        {
	    for(int i=0;i<l;i++)
		answer[i]=(byte)0x00;
	    System.arraycopy(input,0,answer,0,input.length);
	}

	return answer;
    }

    //Convert Int to byte[] with shifting
    public static byte[] toByteArray(int n)
    {
	long length =  Long.toHexString(n).length();
	byte[] answer = new byte[(int) length];
	byte[] finalanswer;

	for(int i = 0;i<length/2+.5;i++)
	    answer[i]=(byte) ((n >>> 8*i) & 0xFF);

	int i =answer.length -1;
	while(answer[i]==(byte)0xFF & i!=0)
	    i--;
       
	finalanswer = new byte[i+1];
	System.arraycopy(answer,0,finalanswer,0,i+1);
	return finalanswer;
    }

    //Convert Long to byte[] of certain length
    public static byte[] toByteArray(long n, int l)
    {
	byte[] input = toByteArray(n);
	byte[] answer = new byte[l];
	if(input.length>l)
	    System.arraycopy(input,0,answer,0,l);
	else 
        {
	    for(int i=0;i<l;i++)
		answer[i]=(byte)0x00;
	    System.arraycopy(input,0,answer,0,input.length);
	}
	return answer;
    }

    //Convert Long to byte[] with shifting
    public static byte[] toByteArray(long n)
    {
	long length =  Long.toHexString(n).length();
	byte[] answer = new byte[(int) length];
	byte[] finalanswer;

	for(int i = 0;i<length/2+.5;i++)
	    answer[i]=(byte) ((n >>> 8*i) & 0xFF);

	int i =answer.length -1;
	while(answer[i]==(byte)0xFF & i!=0)
	    i--;

	finalanswer = new byte[i+1];
	System.arraycopy(answer,0,finalanswer,0,i+1);
	return finalanswer;
    }

    //reverse an array of bytes
    public byte[] reverse(byte[] input)
    {
	byte[] output;
	output = new byte[input.length];
	for(int i=0;i<input.length;i++){
	    output[i]=input[input.length-i-1];
	}
	return output;
    }

    public void close()
    {
        try
        {
            raf.close();
        }
        catch (Exception e) {}
    }

    //READ up to 16 sectors at a time
    public int read(long sectorNumber, byte[] buffer, int size)
    {
	//	System.out.println("Reading Sector number " + sectorNumber + " and size = " + size);

        if (sectorNumber < 95){	// Initial sectors
	    System.arraycopy(start, (int) sectorNumber*512, buffer, 0, size*512);
	    return 0;
	}else if (sectorNumber < 95+2*sectorsPerFAT & sectorNumber>94){	// FAT sectors
	    
	    System.arraycopy(FAT, (int) ((sectorNumber-95) % sectorsPerFAT)*512, buffer, 0, size*512);
	    return 0;
	}else if ((sectorNumber > fileSizeSectors +rootSize+2*sectorsPerFAT+95-1) & (sectorNumber < totalSectors +1)){
	    
	    for (int i = 0;i<size;i++){
		System.arraycopy(empty,0,buffer,512*i,512);
	    }
	    return 0;
	}else if (sectorNumber >  totalSectors){
	    return -1;
	}else if ((sectorNumber > 95 + 2*sectorsPerFAT-1) & (sectorNumber < 95 + 2*sectorsPerFAT + rootSizeClusters*sectorsPerCluster)){//root folder
	    System.out.println("reading root sector...");
	    System.arraycopy(rootdir,0,buffer,0,size*512);
	    return 0;
	}

	//if (sectorNumber > 95+2*sectorsPerFAT & sectorNumber < totalSectors){
	    // data
	try
	    {
		long offset =  (sectorNumber - 95-2*sectorsPerFAT) * 512;
		raf.seek(offset);
		int len = Math.min(size*512, (int) (raf.length() - offset));
		raf.read(buffer, 0, len);
		return 0;
	    }
	catch (Exception e)
	    {
		e.printStackTrace();
		return -1;
	    }

    }

    //write sectors
    public int write(long sectorNumber, byte[] buffer, int size)
    {
	System.out.println("Write attempt");
        if (sectorNumber <95)
        {
            System.arraycopy(buffer, 0, start, (int) sectorNumber*512, size*512);
            return 0;
        }else if (sectorNumber < 95+2*sectorsPerFAT & sectorNumber>94)
        {
            System.arraycopy(buffer, 0,FAT, (int) ((sectorNumber-95) % sectorsPerFAT),  size*512);
            return 0;
        }

	if (sectorNumber > totalSectors){
	    return -1;
	}

        try
        {
            long offset = (sectorNumber - 95-2*sectorsPerFAT-rootSize) * 512;
            raf.seek(offset);
            int len = Math.min(size*512, (int) (raf.length() - offset));
            raf.write(buffer, 0, len);
            return 0;
        }
        catch (Exception e)
        {
            e.printStackTrace();
            return -1;
        }

    }

    public boolean inserted()
    {
        return true;
    }

    public boolean locked()
    {
        return locked;
    }

    public boolean readOnly()
    {
        return true;
    }

    public void setLock(boolean l)
    {
        locked = l;
    }

    public long getTotalSectors()
    {
        return totalSectors;
    }

    public int cylinders()
    {
    	//smaller than 1024
        return cylinders; 
    }

    public int heads()
    {
    	//smaller than 256
        return heads;
    }

    public int sectors()// is this looking for totalSectors or 63??
    {
        return (int) sectorsPerTrack;
    }

    public int type()
    {
        return TYPE_HD;
    }

    public String getImageFileName()
    {
        return source.getAbsolutePath();
    }
}