Merge "Add BitUtils (from "Support multiple filters per association request")"

/*

 * Copyright (C) 2017 The Android Open Source Project

 *

 * 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.android.internal.util;

import android.annotation.Nullable;

import libcore.util.Objects;

import java.util.Arrays;

import java.util.UUID;

public class BitUtils {

    private BitUtils() {}

    public static boolean maskedEquals(long a, long b, long mask) {

        return (a & mask) == (b & mask);

    }

    public static boolean maskedEquals(byte a, byte b, byte mask) {

        return (a & mask) == (b & mask);

    }

    public static boolean maskedEquals(byte[] a, byte[] b, @Nullable byte[] mask) {

        if (a == null || b == null) return a == b;

        Preconditions.checkArgument(a.length == b.length, "Inputs must be of same size");

        if (mask == null) return Arrays.equals(a, b);

        Preconditions.checkArgument(a.length == mask.length, "Mask must be of same size as inputs");

        for (int i = 0; i < mask.length; i++) {

            if (!maskedEquals(a[i], b[i], mask[i])) return false;

        }

        return true;

    }

    public static boolean maskedEquals(UUID a, UUID b, @Nullable UUID mask) {

        if (mask == null) {

            return Objects.equal(a, b);

        }

        return maskedEquals(a.getLeastSignificantBits(), b.getLeastSignificantBits(),

                    mask.getLeastSignificantBits())

                && maskedEquals(a.getMostSignificantBits(), b.getMostSignificantBits(),

                    mask.getMostSignificantBits());

    }

}