2 * Copyright (C) 2017 The Android Open Source Project
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 package com.android.internal.util;
20 import android.annotation.Nullable;
21 import android.text.TextUtils;
23 import libcore.util.Objects;
25 import java.nio.ByteBuffer;
26 import java.util.Arrays;
27 import java.util.UUID;
28 import java.util.function.IntFunction;
31 * A utility class for handling unsigned integers and unsigned arithmetics, as well as syntactic
32 * sugar methods for ByteBuffer. Useful for networking and packet manipulations.
35 public final class BitUtils {
38 public static boolean maskedEquals(long a, long b, long mask) {
39 return (a & mask) == (b & mask);
42 public static boolean maskedEquals(byte a, byte b, byte mask) {
43 return (a & mask) == (b & mask);
46 public static boolean maskedEquals(byte[] a, byte[] b, @Nullable byte[] mask) {
47 if (a == null || b == null) return a == b;
48 Preconditions.checkArgument(a.length == b.length, "Inputs must be of same size");
49 if (mask == null) return Arrays.equals(a, b);
50 Preconditions.checkArgument(a.length == mask.length, "Mask must be of same size as inputs");
51 for (int i = 0; i < mask.length; i++) {
52 if (!maskedEquals(a[i], b[i], mask[i])) return false;
57 public static boolean maskedEquals(UUID a, UUID b, @Nullable UUID mask) {
59 return Objects.equal(a, b);
61 return maskedEquals(a.getLeastSignificantBits(), b.getLeastSignificantBits(),
62 mask.getLeastSignificantBits())
63 && maskedEquals(a.getMostSignificantBits(), b.getMostSignificantBits(),
64 mask.getMostSignificantBits());
67 public static int[] unpackBits(long val) {
68 int size = Long.bitCount(val);
69 int[] result = new int[size];
73 if ((val & 1) == 1) result[index++] = bitPos;
80 public static long packBits(int[] bits) {
88 public static int uint8(byte b) {
92 public static int uint16(short s) {
96 public static long uint32(int i) {
97 return i & 0xffffffffL;
100 public static int bytesToBEInt(byte[] bytes) {
101 return (uint8(bytes[0]) << 24)
102 + (uint8(bytes[1]) << 16)
103 + (uint8(bytes[2]) << 8)
107 public static int bytesToLEInt(byte[] bytes) {
108 return Integer.reverseBytes(bytesToBEInt(bytes));
111 public static int getUint8(ByteBuffer buffer, int position) {
112 return uint8(buffer.get(position));
115 public static int getUint16(ByteBuffer buffer, int position) {
116 return uint16(buffer.getShort(position));
119 public static long getUint32(ByteBuffer buffer, int position) {
120 return uint32(buffer.getInt(position));
123 public static void put(ByteBuffer buffer, int position, byte[] bytes) {
124 final int original = buffer.position();
125 buffer.position(position);
127 buffer.position(original);
130 public static boolean isBitSet(long flags, int bitIndex) {
131 return (flags & bitAt(bitIndex)) != 0;
134 public static long bitAt(int bitIndex) {
135 return 1L << bitIndex;
138 public static String flagsToString(int flags, IntFunction<String> getFlagName) {
139 StringBuilder builder = new StringBuilder();
142 final int flag = 1 << Integer.numberOfTrailingZeros(flags);
144 if (count > 0) builder.append(", ");
145 builder.append(getFlagName.apply(flag));
148 TextUtils.wrap(builder, "[", "]");
149 return builder.toString();