// crudwork
// Copyright 2004 by Steve T. Pham (http://www.crudwork.com)
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with This program. If not, see <http://www.gnu.org/licenses/>.
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
namespace crudwork.Utilities
{
/// <summary>
/// Math Utility
/// </summary>
public static class MathUtil
{
/// <summary>
/// Return the checksum of the buffer
/// </summary>
/// <param name="buffer"></param>
/// <returns></returns>
public static long ComputeChecksum(byte[] buffer)
{
return ComputeChecksum(buffer, 0);
}
/// <summary>
/// Return the checksum of the buffer at the given offset
/// </summary>
/// <param name="buffer"></param>
/// <param name="offset"></param>
/// <returns></returns>
public static long ComputeChecksum(byte[] buffer, int offset)
{
long sum = 0;
for (int i = 0; i < buffer.Length; i++)
{
sum += buffer[i] * (i + 1 + offset);
}
return sum;
}
/// <summary>
/// Return the checksum value of the given filename
/// </summary>
/// <param name="filename"></param>
/// <returns></returns>
public static long ComputeChecksum(string filename)
{
//byte[] buffer = FileUtil.ReadFile(filename, 4096);
//return ComputeChecksum(buffer);
long sum = 0;
int bufSize = 4096;
using (FileStream fs = new FileStream(filename, FileMode.Open, FileAccess.Read))
using (BinaryReader r = new BinaryReader(fs))
{
byte[] readChar = null;
int offset = 0;
do
{
readChar = r.ReadBytes(bufSize);
sum += ComputeChecksum(readChar, offset);
offset += readChar.Length;
} while ((readChar != null) && (readChar.Length > 0));
r.Close();
//fs.Close();
}
return sum;
}
}
}
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