TeraSmartArray.java

/*
 * Copyright 2012 Benjamin Glatzel <benjamin.glatzel@me.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.terasology.model.structures;

import java.util.Arrays;

/**
 * A fast 3D array for efficient storage of 4-bit values.
 *
 * @author Benjamin Glatzel <benjamin.glatzel@me.com>
 */
public class TeraSmartArray {

    private final byte _array[];
    private final int _lX, _lY, _lZ;
    private final int _size, _halfSize;

    /**
     * Init. a new 3D array with the given dimensions.
     */
    public TeraSmartArray(int x, int y, int z) {
        _lX = x;
        _lY = y;
        _lZ = z;

        _size = _lX * _lY * _lZ;
        _array = new byte[_halfSize = _size / 2];
    }

    public TeraSmartArray(TeraSmartArray other) {
        _lX = other._lX;
        _lY = other._lY;
        _lZ = other._lZ;

        _size = _lX * _lY * _lZ;
        _halfSize = _size / 2;
        _array = Arrays.copyOf(other._array, other._array.length);
    }

    /**
     * Returns the byte value at the given position.
     */
    public byte get(int x, int y, int z) {

        int pos = (x * _lX * _lY) + (y * _lX) + z;

        if (x >= _lX || y >= _lY || z >= _lZ || x < 0 || y < 0 || z < 0) {
            throw new IndexOutOfBoundsException(String.format("(%d, %d, %d)", x, y, z));
        }

        if (pos < _halfSize) {
            int bArray = _array[pos] & 0xFF;
            return (byte) ((bArray & 0x0F) & 0xFF);
        }

        int bArray = _array[pos % _halfSize] & 0xFF;
        return (byte) (bArray >> 4);
    }

    /**
     * Sets the byte value for the given position.
     */
    public byte set(int x, int y, int z, byte b) {
        int pos = (x * _lX * _lY) + (y * _lX) + z;

        assert (x < _lX || y < _lY || z < _lZ || x >= 0 || y >= 0 || z >= 0);

        if (pos < _halfSize) {
            int bArray = _array[pos] & 0xFF;
            byte old = (byte) ((bArray & 0x0F) & 0xFF);
            int bInput = b & 0xFF;
            _array[pos] = (byte) ((bInput & 0x0F) | (bArray & 0xF0));
            return old;
        }

        int bArray = _array[pos % _halfSize] & 0xFF;
        byte old = (byte) (bArray >> 4);
        int bInput = b & 0xFF;
        _array[pos % _halfSize] = (byte) ((bArray & 0x0F) | (bInput << 4) & 0xFF);
        return old;
    }

    /**
     * Sets the byte value for the given position.
     */
    public byte set(int x, int y, int z, byte b, byte oldB) {
        int pos = (x * _lX * _lY) + (y * _lX) + z;

        if (x >= _lX || y >= _lY || z >= _lZ || x < 0 || y < 0 || z < 0)
            return 0;

        if (pos < _halfSize) {
            int bArray = _array[pos] & 0xFF;
            byte old = (byte) ((bArray & 0x0F) & 0xFF);
            if (old == oldB) {
                int bInput = b & 0xFF;
                _array[pos] = (byte) ((bInput & 0x0F) | (bArray & 0xF0));
            }
            return old;
        }

        int bArray = _array[pos % _halfSize] & 0xFF;
        byte old = (byte) (bArray >> 4);
        int bInput = b & 0xFF;
        _array[pos % _halfSize] = (byte) ((bArray & 0x0F) | (bInput << 4) & 0xFF);
        return old;
    }

    /**
     * Returns the raw byte at the given index.
     */
    public byte getRawByte(int i) {
        return _array[i];
    }

    /**
     * Sets the raw byte for the given index.
     */
    public void setRawByte(int i, byte b) {
        _array[i] = b;
    }

    /**
     * Returns the size of this array.
     */
    public int size() {
        return _size;
    }

    /**
     * Returns the packed size of this array.
     */
    public int sizePacked() {
        return _halfSize;
    }
}