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/*
* 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 com.facebook.presto.jdbc.internal.airlift.slice;
import static com.facebook.presto.jdbc.internal.airlift.slice.JvmUtils.unsafe;
import static com.facebook.presto.jdbc.internal.airlift.slice.Preconditions.checkPositionIndexes;
import static java.lang.Long.rotateLeft;
public class XxHash64
{
private final static long PRIME64_1 = 0x9E3779B185EBCA87L;
private final static long PRIME64_2 = 0xC2B2AE3D27D4EB4FL;
private final static long PRIME64_3 = 0x165667B19E3779F9L;
private final static long PRIME64_4 = 0x85EBCA77C2b2AE63L;
private final static long PRIME64_5 = 0x27D4EB2F165667C5L;
private final static long DEFAULT_SEED = 0;
public static long hash(long value)
{
long hash = DEFAULT_SEED + PRIME64_5 + SizeOf.SIZE_OF_LONG;
hash = updateTail(hash, value);
hash = finalShuffle(hash);
return hash;
}
public static long hash(Slice data)
{
return hash(data, 0, data.length());
}
public static long hash(long seed, Slice data)
{
return hash(seed, data, 0, data.length());
}
public static long hash(Slice data, int offset, int length)
{
return hash(DEFAULT_SEED, data, offset, length);
}
public static long hash(long seed, Slice data, int offset, int length)
{
checkPositionIndexes(0, offset + length, data.length());
Object base = data.getBase();
long index = data.getAddress() + offset;
long end = index + length;
long hash;
if (length >= 32) {
long v1 = seed + PRIME64_1 + PRIME64_2;
long v2 = seed + PRIME64_2;
long v3 = seed + 0;
long v4 = seed - PRIME64_1;
long limit = end - 32;
do {
v1 = mix(v1, unsafe.getLong(base, index));
index += 8;
v2 = mix(v2, unsafe.getLong(base, index));
index += 8;
v3 = mix(v3, unsafe.getLong(base, index));
index += 8;
v4 = mix(v4, unsafe.getLong(base, index));
index += 8;
}
while (index <= limit);
hash = rotateLeft(v1, 1) + rotateLeft(v2, 7) + rotateLeft(v3, 12) + rotateLeft(v4, 18);
hash = update(hash, v1);
hash = update(hash, v2);
hash = update(hash, v3);
hash = update(hash, v4);
}
else {
hash = seed + PRIME64_5;
}
hash += length;
while (index <= end - 8) {
hash = updateTail(hash, unsafe.getLong(base, index));
index += 8;
}
if (index <= end - 4) {
hash = updateTail(hash, unsafe.getInt(base, index));
index += 4;
}
while (index < end) {
hash = updateTail(hash, unsafe.getByte(base, index));
index++;
}
hash = finalShuffle(hash);
return hash;
}
private static long mix(long current, long value)
{
return rotateLeft(current + value * PRIME64_2, 31) * PRIME64_1;
}
private static long update(long hash, long value)
{
long temp = hash ^ mix(0, value);
return temp * PRIME64_1 + PRIME64_4;
}
private static long updateTail(long hash, long value)
{
long temp = hash ^ mix(0, value);
return rotateLeft(temp, 27) * PRIME64_1 + PRIME64_4;
}
private static long updateTail(long hash, int value)
{
long unsigned = value & 0xFFFF_FFFFL;
long temp = hash ^ (unsigned * PRIME64_1);
return rotateLeft(temp, 23) * PRIME64_2 + PRIME64_3;
}
private static long updateTail(long hash, byte value)
{
int unsigned = value & 0xFF;
long temp = hash ^ (unsigned * PRIME64_5);
return rotateLeft(temp, 11) * PRIME64_1;
}
private static long finalShuffle(long hash)
{
hash ^= hash >>> 33;
hash *= PRIME64_2;
hash ^= hash >>> 29;
hash *= PRIME64_3;
hash ^= hash >>> 32;
return hash;
}
}
