1#region Copyright notice and license
2// Protocol Buffers - Google's data interchange format
3// Copyright 2008 Google Inc.  All rights reserved.
4// https://developers.google.com/protocol-buffers/
5//
6// Redistribution and use in source and binary forms, with or without
7// modification, are permitted provided that the following conditions are
8// met:
9//
10//     * Redistributions of source code must retain the above copyright
11// notice, this list of conditions and the following disclaimer.
12//     * Redistributions in binary form must reproduce the above
13// copyright notice, this list of conditions and the following disclaimer
14// in the documentation and/or other materials provided with the
15// distribution.
16//     * Neither the name of Google Inc. nor the names of its
17// contributors may be used to endorse or promote products derived from
18// this software without specific prior written permission.
19//
20// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
30// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31#endregion
32
33using System;
34
35namespace Google.Protobuf
36{
37    /// <summary>
38    /// Provides a utility routine to copy small arrays much more quickly than Buffer.BlockCopy
39    /// </summary>
40    internal static class ByteArray
41    {
42        /// <summary>
43        /// The threshold above which you should use Buffer.BlockCopy rather than ByteArray.Copy
44        /// </summary>
45        private const int CopyThreshold = 12;
46
47        /// <summary>
48        /// Determines which copy routine to use based on the number of bytes to be copied.
49        /// </summary>
50        internal static void Copy(byte[] src, int srcOffset, byte[] dst, int dstOffset, int count)
51        {
52            if (count > CopyThreshold)
53            {
54                Buffer.BlockCopy(src, srcOffset, dst, dstOffset, count);
55            }
56            else
57            {
58                int stop = srcOffset + count;
59                for (int i = srcOffset; i < stop; i++)
60                {
61                    dst[dstOffset++] = src[i];
62                }
63            }
64        }
65
66        /// <summary>
67        /// Reverses the order of bytes in the array
68        /// </summary>
69        internal static void Reverse(byte[] bytes)
70        {
71            for (int first = 0, last = bytes.Length - 1; first < last; first++, last--)
72            {
73                byte temp = bytes[first];
74                bytes[first] = bytes[last];
75                bytes[last] = temp;
76            }
77        }
78    }
79}