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* Licensed to Elasticsearch under one or more contributor
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* ownership. Elasticsearch licenses this file to you 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.elasticsearch.common.util;
import org.apache.lucene.store.ByteArrayDataInput;
import org.apache.lucene.store.ByteArrayDataOutput;
/** Utility methods to do byte-level encoding. These methods are biased towards little-endian byte order because it is the most
* common byte order and reading several bytes at once may be optimizable in the future with the help of sun.mist.Unsafe. */
public enum ByteUtils {
;
public static final int MAX_BYTES_VLONG = 9;
/** Zig-zag decode. */
public static long zigZagDecode(long n) {
return ((n >>> 1) ^ -(n & 1));
}
/** Zig-zag encode: this helps transforming small signed numbers into small positive numbers. */
public static long zigZagEncode(long n) {
return (n >> 63) ^ (n << 1);
}
/** Write a long in little-endian format. */
public static void writeLongLE(long l, byte[] arr, int offset) {
for (int i = 0; i < 8; ++i) {
arr[offset++] = (byte) l;
l >>>= 8;
}
assert l == 0;
}
/** Write a long in little-endian format. */
public static long readLongLE(byte[] arr, int offset) {
long l = arr[offset++] & 0xFFL;
for (int i = 1; i < 8; ++i) {
l |= (arr[offset++] & 0xFFL) << (8 * i);
}
return l;
}
/** Write an int in little-endian format. */
public static void writeIntLE(int l, byte[] arr, int offset) {
for (int i = 0; i < 4; ++i) {
arr[offset++] = (byte) l;
l >>>= 8;
}
assert l == 0;
}
/** Read an int in little-endian format. */
public static int readIntLE(byte[] arr, int offset) {
int l = arr[offset++] & 0xFF;
for (int i = 1; i < 4; ++i) {
l |= (arr[offset++] & 0xFF) << (8 * i);
}
return l;
}
/** Write a double in little-endian format. */
public static void writeDoubleLE(double d, byte[] arr, int offset) {
writeLongLE(Double.doubleToRawLongBits(d), arr, offset);
}
/** Read a double in little-endian format. */
public static double readDoubleLE(byte[] arr, int offset) {
return Double.longBitsToDouble(readLongLE(arr, offset));
}
/** Write a float in little-endian format. */
public static void writeFloatLE(float d, byte[] arr, int offset) {
writeIntLE(Float.floatToRawIntBits(d), arr, offset);
}
/** Read a float in little-endian format. */
public static float readFloatLE(byte[] arr, int offset) {
return Float.intBitsToFloat(readIntLE(arr, offset));
}
/** Same as DataOutput#writeVLong but accepts negative values (written on 9 bytes). */
public static void writeVLong(ByteArrayDataOutput out, long i) {
for (int k = 0; k < 8 && (i & ~0x7FL) != 0L; ++k) {
out.writeByte((byte)((i & 0x7FL) | 0x80L));
i >>>= 7;
}
out.writeByte((byte)i);
}
/** Same as DataOutput#readVLong but can read negative values (read on 9 bytes). */
public static long readVLong(ByteArrayDataInput in) {
// unwinded because of hotspot bugs, see Lucene's impl
byte b = in.readByte();
if (b >= 0) return b;
long i = b & 0x7FL;
b = in.readByte();
i |= (b & 0x7FL) << 7;
if (b >= 0) return i;
b = in.readByte();
i |= (b & 0x7FL) << 14;
if (b >= 0) return i;
b = in.readByte();
i |= (b & 0x7FL) << 21;
if (b >= 0) return i;
b = in.readByte();
i |= (b & 0x7FL) << 28;
if (b >= 0) return i;
b = in.readByte();
i |= (b & 0x7FL) << 35;
if (b >= 0) return i;
b = in.readByte();
i |= (b & 0x7FL) << 42;
if (b >= 0) return i;
b = in.readByte();
i |= (b & 0x7FL) << 49;
if (b >= 0) return i;
b = in.readByte();
i |= (b & 0xFFL) << 56;
return i;
}
}