1/*
2 * Copyright (C) 2014 Square, Inc.
3 *
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
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
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.
15 */
16package okio;
17
18import java.nio.charset.Charset;
19
20final class Util {
21  /** A cheap and type-safe constant for the UTF-8 Charset. */
22  public static final Charset UTF_8 = Charset.forName("UTF-8");
23
24  private Util() {
25  }
26
27  public static void checkOffsetAndCount(long size, long offset, long byteCount) {
28    if ((offset | byteCount) < 0 || offset > size || size - offset < byteCount) {
29      throw new ArrayIndexOutOfBoundsException(
30          String.format("size=%s offset=%s byteCount=%s", size, offset, byteCount));
31    }
32  }
33
34  public static short reverseBytesShort(short s) {
35    int i = s & 0xffff;
36    int reversed = (i & 0xff00) >>> 8
37        |          (i & 0x00ff)  << 8;
38    return (short) reversed;
39  }
40
41  public static int reverseBytesInt(int i) {
42    return (i & 0xff000000) >>> 24
43        |  (i & 0x00ff0000) >>>  8
44        |  (i & 0x0000ff00)  <<  8
45        |  (i & 0x000000ff)  << 24;
46  }
47
48  public static long reverseBytesLong(long v) {
49    return (v & 0xff00000000000000L) >>> 56
50        |  (v & 0x00ff000000000000L) >>> 40
51        |  (v & 0x0000ff0000000000L) >>> 24
52        |  (v & 0x000000ff00000000L) >>>  8
53        |  (v & 0x00000000ff000000L)  <<  8
54        |  (v & 0x0000000000ff0000L)  << 24
55        |  (v & 0x000000000000ff00L)  << 40
56        |  (v & 0x00000000000000ffL)  << 56;
57  }
58
59  /**
60   * Throws {@code t}, even if the declared throws clause doesn't permit it.
61   * This is a terrible – but terribly convenient – hack that makes it easy to
62   * catch and rethrow exceptions after cleanup. See Java Puzzlers #43.
63   */
64  public static void sneakyRethrow(Throwable t) {
65    Util.<Error>sneakyThrow2(t);
66  }
67
68  @SuppressWarnings("unchecked")
69  private static <T extends Throwable> void sneakyThrow2(Throwable t) throws T {
70    throw (T) t;
71  }
72
73  public static boolean arrayRangeEquals(
74      byte[] a, int aOffset, byte[] b, int bOffset, int byteCount) {
75    for (int i = 0; i < byteCount; i++) {
76      if (a[i + aOffset] != b[i + bOffset]) return false;
77    }
78    return true;
79  }
80}
81