Aaru/DiscImageChef.Checksums/FletcherContext.cs

/***************************************************************************
The Disc Image Chef
----------------------------------------------------------------------------
 
Filename       : FletcherContext.cs
Version        : 1.0
Author(s)      : Natalia Portillo
 
Component      : Checksums.

Revision       : $Revision$
Last change by : $Author$
Date           : $Date$
 
--[ Description ] ----------------------------------------------------------
 
Implements Fletcher-32 and Fletcher-16 algorithms.
 
--[ License ] --------------------------------------------------------------
 
    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/>.

----------------------------------------------------------------------------
Copyright (C) 2011-2015 Claunia.com
****************************************************************************/
//$Id$
using System;
using System.Text;
using System.IO;

namespace DiscImageChef.Checksums
{
    public class Fletcher32Context
    {
        UInt16 sum1, sum2;
        byte oddValue;
        bool inodd;

        /// <summary>
        /// Initializes the Fletcher32 sums
        /// </summary>
        public void Init()
        {
            sum1 = 0xFFFF;
            sum2 = 0xFFFF;
            oddValue = 0;
            inodd = false;
        }

        /// <summary>
        /// Updates the hash with data.
        /// </summary>
        /// <param name="data">Data buffer.</param>
        /// <param name="len">Length of buffer to hash.</param>
        public void Update(byte[] data, uint len)
        {
            UInt16 block;
            if (!inodd)
            {
                // Odd size
                if (len % 2 != 0)
                {
                    oddValue = data[len - 1];
                    inodd = true;

                    for (int i = 0; i < len - 1; i += 2)
                    {
                        block = BigEndianBitConverter.ToUInt16(data, i);
                        sum1 = (UInt16)((sum1 + block) % 0xFFFF);
                        sum2 = (UInt16)((sum2 + sum1) % 0xFFFF);
                    }
                }
                else
                {
                    inodd = false;
                    for (int i = 0; i < len; i += 2)
                    {
                        block = BigEndianBitConverter.ToUInt16(data, i);
                        sum1 = (UInt16)((sum1 + block) % 0xFFFF);
                        sum2 = (UInt16)((sum2 + sum1) % 0xFFFF);
                    }
                }
            }
            // Carrying odd
            else
            {
                byte[] oddData = new byte[2];
                oddData[0] = oddValue;
                oddData[1] = data[0];

                block = BigEndianBitConverter.ToUInt16(oddData, 0);
                sum1 = (UInt16)((sum1 + block) % 0xFFFF);
                sum2 = (UInt16)((sum2 + sum1) % 0xFFFF);

                // Even size, carrying odd
                if (len % 2 == 0)
                {
                    oddValue = data[len - 1];
                    inodd = true;

                    for (int i = 1; i < len - 1; i += 2)
                    {
                        block = BigEndianBitConverter.ToUInt16(data, i);
                        sum1 = (UInt16)((sum1 + block) % 0xFFFF);
                        sum2 = (UInt16)((sum2 + sum1) % 0xFFFF);
                    }
                }
                else
                {
                    inodd = false;
                    for (int i = 1; i < len; i += 2)
                    {
                        block = BigEndianBitConverter.ToUInt16(data, i);
                        sum1 = (UInt16)((sum1 + block) % 0xFFFF);
                        sum2 = (UInt16)((sum2 + sum1) % 0xFFFF);
                    }
                }
            }
        }

        /// <summary>
        /// Updates the hash with data.
        /// </summary>
        /// <param name="data">Data buffer.</param>
        public void Update(byte[] data)
        {
            Update(data, (uint)data.Length);
        }

        /// <summary>
        /// Returns a byte array of the hash value.
        /// </summary>
        public byte[] Final()
        {
            UInt32 finalSum = (UInt32)(sum1 + (sum2 << 16));
            return BigEndianBitConverter.GetBytes(finalSum);
        }

        /// <summary>
        /// Returns a hexadecimal representation of the hash value.
        /// </summary>
        public string End()
        {
            UInt32 finalSum = (UInt32)(sum1 + (sum2 << 16));
            StringBuilder fletcherOutput = new StringBuilder();

            for (int i = 0; i < BigEndianBitConverter.GetBytes(finalSum).Length; i++)
            {
                fletcherOutput.Append(BigEndianBitConverter.GetBytes(finalSum)[i].ToString("x2"));
            }

            return fletcherOutput.ToString();
        }

        /// <summary>
        /// Gets the hash of a file
        /// </summary>
        /// <param name="filename">File path.</param>
        public static byte[] File(string filename)
        {
            byte[] hash;
            File(filename, out hash);
            return hash;
        }

        /// <summary>
        /// Gets the hash of a file in hexadecimal and as a byte array.
        /// </summary>
        /// <param name="filename">File path.</param>
        /// <param name="hash">Byte array of the hash value.</param>
        public static string File(string filename, out byte[] hash)
        {
            FileStream fileStream = new FileStream(filename, FileMode.Open);
            UInt16 localSum1, localSum2, block;
            UInt32 finalSum;
            byte[] blockBytes;

            localSum1 = 0xFFFF;
            localSum2 = 0xFFFF;
            block = 0;

            if (fileStream.Length % 2 == 0)
            {
                for (int i = 0; i < fileStream.Length; i += 2)
                {
                    blockBytes = new byte[2];
                    fileStream.Read(blockBytes, 0, 2);
                    block = BigEndianBitConverter.ToUInt16(blockBytes, 0);
                    localSum1 = (UInt16)((localSum1 + block) % 0xFFFF);
                    localSum2 = (UInt16)((localSum2 + localSum1) % 0xFFFF);
                }
            }
            else
            {
                for (int i = 0; i < fileStream.Length - 1; i += 2)
                {
                    blockBytes = new byte[2];
                    fileStream.Read(blockBytes, 0, 2);
                    block = BigEndianBitConverter.ToUInt16(blockBytes, 0);
                    localSum1 = (UInt16)((localSum1 + block) % 0xFFFF);
                    localSum2 = (UInt16)((localSum2 + localSum1) % 0xFFFF);
                }

                byte[] oddData = new byte[2];
                oddData[0] = (byte)fileStream.ReadByte();
                oddData[1] = 0;

                block = BigEndianBitConverter.ToUInt16(oddData, 0);
                localSum1 = (UInt16)((localSum1 + block) % 0xFFFF);
                localSum2 = (UInt16)((localSum2 + localSum1) % 0xFFFF);
            }

            finalSum = (UInt32)(localSum1 + (localSum2 << 16));

            hash = BitConverter.GetBytes(finalSum);

            StringBuilder fletcherOutput = new StringBuilder();

            for (int i = 0; i < hash.Length; i++)
            {
                fletcherOutput.Append(hash[i].ToString("x2"));
            }

            return fletcherOutput.ToString();
        }

        /// <summary>
        /// Gets the hash of the specified data buffer.
        /// </summary>
        /// <param name="data">Data buffer.</param>
        /// <param name="len">Length of the data buffer to hash.</param>
        /// <param name="hash">Byte array of the hash value.</param>
        public static string Data(byte[] data, uint len, out byte[] hash)
        {
            UInt16 localSum1, localSum2, block;
            UInt32 finalSum;

            localSum1 = 0xFFFF;
            localSum2 = 0xFFFF;
            block = 0;

            if (len % 2 == 0)
            {
                for (int i = 0; i < len; i += 2)
                {
                    block = BigEndianBitConverter.ToUInt16(data, i);
                    localSum1 = (UInt16)((localSum1 + block) % 0xFFFF);
                    localSum2 = (UInt16)((localSum2 + localSum1) % 0xFFFF);
                }
            }
            else
            {
                for (int i = 0; i < len - 1; i += 2)
                {
                    block = BigEndianBitConverter.ToUInt16(data, i);
                    localSum1 = (UInt16)((localSum1 + block) % 0xFFFF);
                    localSum2 = (UInt16)((localSum2 + localSum1) % 0xFFFF);
                }

                byte[] oddData = new byte[2];
                oddData[0] = data[len - 1];
                oddData[1] = 0;

                block = BigEndianBitConverter.ToUInt16(oddData, 0);
                localSum1 = (UInt16)((localSum1 + block) % 0xFFFF);
                localSum2 = (UInt16)((localSum2 + localSum1) % 0xFFFF);
            }

            finalSum = (UInt32)(localSum1 + (localSum2 << 16));

            hash = BitConverter.GetBytes(finalSum);

            StringBuilder fletcherOutput = new StringBuilder();

            for (int i = 0; i < hash.Length; i++)
            {
                fletcherOutput.Append(hash[i].ToString("x2"));
            }

            return fletcherOutput.ToString();
        }

        /// <summary>
        /// Gets the hash of the specified data buffer.
        /// </summary>
        /// <param name="data">Data buffer.</param>
        /// <param name="hash">Byte array of the hash value.</param>
        public static string Data(byte[] data, out byte[] hash)
        {
            return Data(data, (uint)data.Length, out hash);
        }
    }

    public class Fletcher16Context
    {
        byte sum1, sum2;

        /// <summary>
        /// Initializes the Fletcher16 sums
        /// </summary>
        public void Init()
        {
            sum1 = 0xFF;
            sum2 = 0xFF;
        }

        /// <summary>
        /// Updates the hash with data.
        /// </summary>
        /// <param name="data">Data buffer.</param>
        /// <param name="len">Length of buffer to hash.</param>
        public void Update(byte[] data, uint len)
        {
            for (int i = 0; i < len; i++)
            {
                sum1 = (byte)((sum1 + data[i]) % 0xFF);
                sum2 = (byte)((sum2 + sum1) % 0xFF);
            }
        }

        /// <summary>
        /// Updates the hash with data.
        /// </summary>
        /// <param name="data">Data buffer.</param>
        public void Update(byte[] data)
        {
            Update(data, (uint)data.Length);
        }

        /// <summary>
        /// Returns a byte array of the hash value.
        /// </summary>
        public byte[] Final()
        {
            UInt16 finalSum = (UInt16)(sum1 + (sum2 << 8));
            return BigEndianBitConverter.GetBytes(finalSum);
        }

        /// <summary>
        /// Returns a hexadecimal representation of the hash value.
        /// </summary>
        public string End()
        {
            UInt16 finalSum = (UInt16)(sum1 + (sum2 << 8));
            StringBuilder fletcherOutput = new StringBuilder();

            for (int i = 0; i < BigEndianBitConverter.GetBytes(finalSum).Length; i++)
            {
                fletcherOutput.Append(BigEndianBitConverter.GetBytes(finalSum)[i].ToString("x2"));
            }

            return fletcherOutput.ToString();
        }

        /// <summary>
        /// Gets the hash of a file
        /// </summary>
        /// <param name="filename">File path.</param>
        public static byte[] File(string filename)
        {
            byte[] hash;
            File(filename, out hash);
            return hash;
        }

        /// <summary>
        /// Gets the hash of a file in hexadecimal and as a byte array.
        /// </summary>
        /// <param name="filename">File path.</param>
        /// <param name="hash">Byte array of the hash value.</param>
        public static string File(string filename, out byte[] hash)
        {
            FileStream fileStream = new FileStream(filename, FileMode.Open);
            byte localSum1, localSum2, block;
            UInt16 finalSum;

            localSum1 = 0xFF;
            localSum2 = 0xFF;
            block = 0;

            for (int i = 0; i < fileStream.Length; i += 2)
            {
                block = (byte)fileStream.ReadByte();
                localSum1 = (byte)((localSum1 + block) % 0xFF);
                localSum2 = (byte)((localSum2 + localSum1) % 0xFF);
            }

            finalSum = (UInt16)(localSum1 + (localSum2 << 8));

            hash = BitConverter.GetBytes(finalSum);

            StringBuilder fletcherOutput = new StringBuilder();

            for (int i = 0; i < hash.Length; i++)
            {
                fletcherOutput.Append(hash[i].ToString("x2"));
            }

            return fletcherOutput.ToString();
        }

        /// <summary>
        /// Gets the hash of the specified data buffer.
        /// </summary>
        /// <param name="data">Data buffer.</param>
        /// <param name="len">Length of the data buffer to hash.</param>
        /// <param name="hash">Byte array of the hash value.</param>
        public static string Data(byte[] data, uint len, out byte[] hash)
        {
            byte localSum1, localSum2;
            UInt16 finalSum;

            localSum1 = 0xFF;
            localSum2 = 0xFF;

            for (int i = 0; i < len; i++)
            {
                localSum1 = (byte)((localSum1 + data[i]) % 0xFF);
                localSum2 = (byte)((localSum2 + localSum1) % 0xFF);
            }

            finalSum = (UInt16)(localSum1 + (localSum2 << 8));

            hash = BitConverter.GetBytes(finalSum);

            StringBuilder fletcherOutput = new StringBuilder();

            for (int i = 0; i < hash.Length; i++)
            {
                fletcherOutput.Append(hash[i].ToString("x2"));
            }

            return fletcherOutput.ToString();
        }

        /// <summary>
        /// Gets the hash of the specified data buffer.
        /// </summary>
        /// <param name="data">Data buffer.</param>
        /// <param name="hash">Byte array of the hash value.</param>
        public static string Data(byte[] data, out byte[] hash)
        {
            return Data(data, (uint)data.Length, out hash);
        }
    }
}