SquirrelJME/SquirrelJME

// -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
// ---------------------------------------------------------------------------
// SquirrelJME
//     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
// ---------------------------------------------------------------------------
// SquirrelJME is under the Mozilla Public License Version 2.0.
// See license.mkd for licensing and copyright information.
// ---------------------------------------------------------------------------

package net.multiphasicapps.zip.blockreader;

import java.io.EOFException;
import java.io.IOException;

/**
 * This wraps an array and provides it to the block accessor interface so that
 * ZIP files may be read from arrays.
 *
 * @since 2016/12/27
 */
@SuppressWarnings("DuplicateThrows")
public class ArrayBlockAccessor
    implements BlockAccessor
{
    /** The internal buffer. */
    protected final byte[] buffer;
    
    /** The offset into the buffer. */
    protected final int offset;
    
    /** The number of bytes available. */
    protected final int length;
    
    /**
     * Initializes the block accessor which uses the entire array.
     *
     * @param __b The array to wrap.
     * @throws NullPointerException On null arguments.
     * @since 2016/12/27
     */
    public ArrayBlockAccessor(byte[] __b)
        throws NullPointerException
    {
        this(__b, 0, __b.length);
    }
    
    /**
     * Initializes the block accessor which uses the entire array.
     *
     * @param __b The array to wrap.
     * @param __o The offset into the array.
     * @param __l The number of bytes to make available.
     * @throws ArrayIndexOutOfBoundsException If the offset and/or length
     * are negative or exceed the array bounds.
     * @throws NullPointerException On null arguments.
     * @since 2016/12/27
     */
    public ArrayBlockAccessor(byte[] __b, int __o, int __l)
        throws ArrayIndexOutOfBoundsException, NullPointerException
    {
        // Check
        if (__b == null)
            throw new NullPointerException("NARG");
        if (__o < 0 || __l < 0 || (__o + __l) < 0 || (__o + __l) > __b.length)
            throw new ArrayIndexOutOfBoundsException("AIOB");
        
        // Set
        this.buffer = __b;
        this.offset = __o;
        this.length = __l;
    }
    
    /**
     * {@inheritDoc}
     * @since 2016/12/27
     */
    @Override
    public void close()
    {
    }
    
    /**
     * {@inheritDoc}
     * @since 2016/12/29
     */
    @Override
    public byte read(long __addr)
        throws EOFException, IOException
    {
        /* {@squirreljme.error BF04 Cannot read from a negative offset.} */
        if (__addr < 0)
            throw new IOException("BF04");
        
        /* {@squirreljme.error BF05 Read past end of the block.} */
        if (__addr > this.length)
            throw new EOFException("BF05");
        
        // Get
        return this.buffer[this.offset + (int)__addr];
    }
    
    /**
     * {@inheritDoc}
     * @since 2016/12/27
     */
    @Override
    public int read(long __addr, byte[] __b, int __o, int __l)
        throws ArrayIndexOutOfBoundsException, IOException,
            NullPointerException
    {
        // Check
        if (__b == null)
            throw new NullPointerException("NARG");
        if (__o < 0 || __l < 0 || (__o + __l) < 0 || (__o + __l) > __b.length)
            throw new ArrayIndexOutOfBoundsException("AIOB");
        
        /* {@squirreljme.error BF06 Cannot read from a negative offset.} */
        if (__addr < 0)
            throw new IOException("BF06");
        
        // After the end?
        int length = this.length;
        if (__addr >= length)
            return -1;
        
        // Number of bytes to actually read
        int addr = (int)__addr;
        int actual = Math.min(__l, length - addr);
        
        // Read bytes
        byte[] buffer = this.buffer;
        int offset = this.offset;
        for (int i = 0, s = offset + addr, d = __o; i < actual; i++, s++, d++)
            __b[d] = buffer[s];
        
        // Return the actual number of bytes read
        return actual;
    }
    
    /**
     * {@inheritDoc}
     * @since 2016/12/27
     */
    @Override
    public long size()
    {
        return this.length;
    }
}