/**
* Copyright 2014 National University of Ireland, Galway.
*
* This file is part of the SIREn project. Project and contact information:
*
* https://github.com/rdelbru/SIREn
*
* 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.sindice.siren.util;
import java.nio.ByteBuffer;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.util.BytesRef;
/**
* Contains methods to encode an integer into a byte array and decode a byte
* array into an integer.
*/
public class CodecUtils {
/**
* Convert a byte array to an int (32bit word).
*
* @param src The byte array (length = 4)
* @param offset The offset of the encoded integer in the byte array
* @return The integer
*/
public static int byteArrayToInt(final byte[] src, final int offset) {
int value = 0;
for (int i = offset; i < offset + 4; i++) {
value += (src[i] & 0x000000FF) << (4 - 1 - i) * 8;
}
return value;
}
/**
* Convert an integer to a byte array.
*
* @param x The integer
* @param dst The byte array (length = 4)
* @param offset The offset of the encoded integer in the byte array
*/
public static final void intToByteArray(final int x, final byte[] dst, final int offset) {
dst[offset + 3] = (byte) (x & 0x000000ff);
dst[offset + 2] = (byte) ((x & 0x0000ff00) >>> 8);
dst[offset + 1] = (byte) ((x & 0x00ff0000) >>> 16);
dst[offset + 0] = (byte) ((x & 0xff000000) >>> 24);
}
/**
* Writes an integer in a variable-length format. Writes between one and
* five bytes. Smaller values take fewer bytes. Negative numbers are not
* supported.
* @see IndexInput#readVInt()
*/
public static void vIntToByteArray(int i, final ByteBuffer bb) {
while ((i & ~0x7F) != 0) {
bb.put((byte) ((i & 0x7f) | 0x80));
i >>>= 7;
}
bb.put((byte) i);
}
/**
* Reads an int stored in variable-length format. Reads between one and five
* bytes. Smaller values take fewer bytes. Negative numbers are not supported.
*/
public static int byteArrayToVInt(final BytesRef ref) {
byte b = ref.bytes[ref.offset++];
int i = b & 0x7F;
for (int shift = 7; (b & 0x80) != 0; shift += 7) {
b = ref.bytes[ref.offset++];
i |= (b & 0x7F) << shift;
}
return i;
}
/**
* Writes an integer in a variable-length format. Writes between one and
* five bytes. Smaller values take fewer bytes. Negative numbers are not
* supported.
* @see IndexInput#readVInt()
*/
public static void appendVInt(int i, final BytesRef ref) {
while ((i & ~0x7F) != 0) {
ref.bytes[ref.offset++] = (byte) ((i & 0x7f) | 0x80);
i >>>= 7;
}
ref.bytes[ref.offset++] = (byte) i;
}
/**
* Write the content, i.e. bits, of a byte into the string buffer.
* </br>
* Code taken from Lucene-1410.
*
* @param b The byte
* @param buf the string buffer
*/
private static void writeBits(final int b, final StringBuffer buf) {
for (int i = 7; i >= 0; i--) {
buf.append((b >>> i) & 1);
}
}
/**
* Display the content, i.e. bits, of a byte array. Write to stdout the
* content of the array on a single line.
* </br>
* Code taken from Lucene-1410.
*
* @param array The byte array
*/
public static void writeBytes(final byte[] array) {
final StringBuffer buf = new StringBuffer();
for (final byte element : array) {
CodecUtils.writeBits(element & 255, buf);
buf.append(' ');
}
System.out.println(buf);
}
/**
* Display the content, i.e. bits, of a byte array. Write to stdout 4 bytes
* per lines.
* </br>
* Code taken from Lucene-1410.
*
* @param array The byte array
*/
public static void writeIndentBytes(final byte[] array) {
final StringBuffer buf = new StringBuffer();
for (int i = 0; i < array.length; i++) {
CodecUtils.writeBits(array[i] & 255, buf);
if (((i+1) % 4) != 0) {
buf.append(' ');
} else {
System.out.println(buf);
buf.setLength(0);
}
}
}
}