Files
duplicati/Duplicati/Library/Main/Database/HashLookupHelper.cs
T

89 lines
3.0 KiB
C#

// Copyright (C) 2013, The Duplicati Team
// http://www.duplicati.com, info@duplicati.com
//
// This library is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 2.1 of the
// License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
using System;
using System.Collections.Generic;
namespace Duplicati.Library.Main
{
/// <summary>
/// Lookup table for hashes
/// </summary>
public class HashLookupHelper<T>
{
/// <summary>
/// The lookup table
/// </summary>
private readonly SortedList<string, T>[] m_lookup;
/// <summary>
/// The number of entries in the table
/// </summary>
private readonly ulong m_entries;
/// <summary>
/// Initializes a new instance of the <see cref="Duplicati.Library.Main.HashLookupHelper{T}"/> class.
/// </summary>
/// <param name="maxmemory">The maximum amount of bytes to use for the lookup table</param>
public HashLookupHelper (ulong maxmemory)
{
m_entries = Math.Max(16, maxmemory / (ulong)IntPtr.Size);
m_lookup = new SortedList<string, T>[m_entries];
}
/// <summary>
/// Hex digit ASCII lookup table
/// </summary>
private static readonly byte[] HEXTB = new byte[128];
/// <summary>
/// Base64 digit ASCII lookup table
/// </summary>
private static readonly byte[] BAS64TB = new byte[128];
/// <summary>
/// Initializes the lookup
/// </summary>
static HashLookupHelper()
{
for(byte i = 0; i < 10; i++)
HEXTB['0' + i] = i;
for (byte i = 0; i < 6; i++)
{
//Case insensitive support
HEXTB['A' + i] = (byte)(i + 10);
HEXTB['a' + i] = (byte)(i + 10);
}
for (byte i = 0; i < 26; i++)
BAS64TB['A' + i] = i;
for (byte i = 0; i < 26; i++)
BAS64TB['a' + i] = (byte)(i + 26);
for (byte i = 0; i < 10; i++)
BAS64TB['0' + i] = (byte)(i + 52);
BAS64TB['+'] = 62;
BAS64TB['/'] = 63;
//Base64 URL support
BAS64TB['-'] = 62;
BAS64TB['_'] = 63;
}
}
}