// =================================================================================================
// Copyright 2011 Twitter, Inc.
// -------------------------------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this work except in compliance with the License.
// You may obtain a copy of the License in the LICENSE file, or 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.twitter.common.collections;
import com.google.common.base.Preconditions;
/**
* Convenience class for doing bit-level operations on ints and longs.
*
* @author William Farner
*/
public final class Bits {
private static final int LSB = 0;
private static final int INT_MSB = 31;
private static final int LONG_MSB = 63;
private Bits() {
// Utility.
}
/**
* Tests whether a bit is set in an int value.
*
* @param value The bit field to test.
* @param bit The index of the bit to test, where bit 0 is the LSB.
* @return {@code true} if the bit is set, {@code false} otherwise.
*/
public static boolean isBitSet(int value, int bit) {
Preconditions.checkState(bit >= LSB);
Preconditions.checkState(bit <= INT_MSB);
int mask = 1 << bit;
return (value & mask) != 0;
}
/**
* Tests whether a bit is set in a long value.
*
* @param value The bit field to test.
* @param bit The index of the bit to test, where bit 0 is the LSB.
* @return {@code true} if the bit is set, {@code false} otherwise.
*/
public static boolean isBitSet(long value, int bit) {
Preconditions.checkState(bit >= LSB);
Preconditions.checkState(bit <= LONG_MSB);
long mask = 1L << bit;
return (value & mask) != 0;
}
/**
* Sets a bit in an int value.
*
* @param value The bit field to modify.
* @param bit The index of the bit to set, where bit 0 is the LSB.
* @return The original value, with the indexed bit set.
*/
public static int setBit(int value, int bit) {
Preconditions.checkState(bit >= LSB);
Preconditions.checkState(bit <= INT_MSB);
int mask = 1 << bit;
return value | mask;
}
/**
* Sets a bit in a long value.
*
* @param value The bit field to modify.
* @param bit The index of the bit to set, where bit 0 is the LSB.
* @return The original value, with the indexed bit set.
*/
public static long setBit(long value, int bit) {
Preconditions.checkState(bit >= LSB);
Preconditions.checkState(bit <= LONG_MSB);
long mask = 1L << bit;
return value | mask;
}
/**
* Clears a bit in an int value.
*
* @param value The bit field to modify.
* @param bit The index of the bit to clear, where bit 0 is the LSB.
* @return The original value, with the indexed bit clear.
*/
public static int clearBit(int value, int bit) {
Preconditions.checkState(bit >= LSB);
Preconditions.checkState(bit <= INT_MSB);
int mask = ~setBit(0, bit);
return value & mask;
}
/**
* Clears a bit in a long value.
*
* @param value The bit field to modify.
* @param bit The index of the bit to clear, where bit 0 is the LSB.
* @return The original value, with the indexed bit clear.
*/
public static long clearBit(long value, int bit) {
Preconditions.checkState(bit >= LSB);
Preconditions.checkState(bit <= LONG_MSB);
long mask = ~setBit(0L, bit);
return value & mask;
}
}