PartitionChunk.java

/*
 * This file is part of SpoutcraftPlugin.
 *
 * Copyright (c) 2011 SpoutcraftDev <http://spoutcraft.org//>
 * SpoutcraftPlugin is licensed under the GNU Lesser General Public License.
 *
 * SpoutcraftPlugin is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * SpoutcraftPlugin is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.getspout.spout.netcache;

public class PartitionChunk {
	static public void copyToChunkData(byte[] chunkData, int blockNum, byte[] partition, int dataLength) {
		int j = blockNum << 11;

		boolean clear = partition == null;

		if (clear) {
			for (int i = 0; i < 2048 && j < dataLength; i++) {
				chunkData[j++] = 0;
			}
		} else {
			for (int i = 0; i < 2048 && j < dataLength; i++) {
				chunkData[j++] = partition[i];
			}
		}
	}

	static public void copyFromChunkData(byte[] chunkData, int blockNum, byte[] partition, int dataLength) {
		int j = blockNum << 11;

		int i = 0;
		for (i = 0; i < 2048 && j < dataLength; i++) {
			partition[i] = chunkData[j++];
		}
		for (; i < 2048; i++) {
			partition[i] = 0;
		}
	}

	static public long getHash(byte[] chunkData, int blockNum, int base) {
		int p = blockNum * 8 + base;
		long hash = 0;
		hash = hash << 8 | (((long) chunkData[p++]) & 0xFFL);
		hash = hash << 8 | (((long) chunkData[p++]) & 0xFFL);
		hash = hash << 8 | (((long) chunkData[p++]) & 0xFFL);
		hash = hash << 8 | (((long) chunkData[p++]) & 0xFFL);
		hash = hash << 8 | (((long) chunkData[p++]) & 0xFFL);
		hash = hash << 8 | (((long) chunkData[p++]) & 0xFFL);
		hash = hash << 8 | (((long) chunkData[p++]) & 0xFFL);
		hash = hash << 8 | (((long) chunkData[p++]) & 0xFFL);
		return hash;
	}

	static public void setHash(byte[] chunkData, int blockNum, long hash, int base) {
		int p = blockNum * 8 + base;
		chunkData[p++] = (byte) (hash >> 56);
		chunkData[p++] = (byte) (hash >> 48);
		chunkData[p++] = (byte) (hash >> 40);
		chunkData[p++] = (byte) (hash >> 32);
		chunkData[p++] = (byte) (hash >> 24);
		chunkData[p++] = (byte) (hash >> 16);
		chunkData[p++] = (byte) (hash >> 8);
		chunkData[p++] = (byte) (hash >> 0);
	}

	static public int getInt(byte[] chunkData, int blockNum, int base) {
		int p = blockNum * 4 + base;
		int hash = 0;
		hash = hash << 8 | (((int) chunkData[p++]) & 0xFF);
		hash = hash << 8 | (((int) chunkData[p++]) & 0xFF);
		hash = hash << 8 | (((int) chunkData[p++]) & 0xFF);
		hash = hash << 8 | (((int) chunkData[p++]) & 0xFF);
		return hash;
	}

	static public void setInt(byte[] chunkData, int blockNum, int hash, int base) {
		int p = blockNum * 4 + base;
		chunkData[p++] = (byte) (hash >> 24);
		chunkData[p++] = (byte) (hash >> 16);
		chunkData[p++] = (byte) (hash >> 8);
		chunkData[p++] = (byte) (hash >> 0);
	}

	public static long hash(final byte[] a) {
		return hash(a, 0, a.length);
	}

	public static long hash(final byte[] a, final int off, final int len) {
		long h = 1;
		int end = off + len;
		for (int i = off; i < end; i++) {
			h += (h << 5) + (long) a[i];
		}
		return h;
	}
}