93 lines
3.1 KiB
C#
93 lines
3.1 KiB
C#
//
|
|
// Copyright (c) 2008-2011, Kenneth Bell
|
|
//
|
|
// Permission is hereby granted, free of charge, to any person obtaining a
|
|
// copy of this software and associated documentation files (the "Software"),
|
|
// to deal in the Software without restriction, including without limitation
|
|
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
|
|
// and/or sell copies of the Software, and to permit persons to whom the
|
|
// Software is furnished to do so, subject to the following conditions:
|
|
//
|
|
// The above copyright notice and this permission notice shall be included in
|
|
// all copies or substantial portions of the Software.
|
|
//
|
|
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
|
|
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
|
|
// DEALINGS IN THE SOFTWARE.
|
|
//
|
|
|
|
using System;
|
|
|
|
namespace DiscUtils.Compression
|
|
{
|
|
/// <summary>
|
|
/// Implementation of the Adler-32 checksum algorithm.
|
|
/// </summary>
|
|
public class Adler32
|
|
{
|
|
private uint _a;
|
|
private uint _b;
|
|
|
|
/// <summary>
|
|
/// Initializes a new instance of the Adler32 class.
|
|
/// </summary>
|
|
public Adler32()
|
|
{
|
|
_a = 1;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Gets the checksum of all data processed so far.
|
|
/// </summary>
|
|
public int Value
|
|
{
|
|
get { return (int)(_b << 16 | _a); }
|
|
}
|
|
|
|
/// <summary>
|
|
/// Provides data that should be checksummed.
|
|
/// </summary>
|
|
/// <param name="buffer">Buffer containing the data to checksum.</param>
|
|
/// <param name="offset">Offset of the first byte to checksum.</param>
|
|
/// <param name="count">The number of bytes to checksum.</param>
|
|
/// <remarks>
|
|
/// Call this method repeatedly until all checksummed
|
|
/// data has been processed.
|
|
/// </remarks>
|
|
public void Process(byte[] buffer, int offset, int count)
|
|
{
|
|
if (buffer == null)
|
|
{
|
|
throw new ArgumentNullException(nameof(buffer));
|
|
}
|
|
|
|
if (offset < 0 || offset > buffer.Length)
|
|
{
|
|
throw new ArgumentException("Offset outside of array bounds", nameof(offset));
|
|
}
|
|
|
|
if (count < 0 || offset + count > buffer.Length)
|
|
{
|
|
throw new ArgumentException("Array index out of bounds", nameof(count));
|
|
}
|
|
|
|
int processed = 0;
|
|
while (processed < count)
|
|
{
|
|
int innerEnd = Math.Min(count, processed + 2000);
|
|
while (processed < innerEnd)
|
|
{
|
|
_a += buffer[processed++];
|
|
_b += _a;
|
|
}
|
|
|
|
_a %= 65521;
|
|
_b %= 65521;
|
|
}
|
|
}
|
|
}
|
|
} |