// IChecksum.cs - Interface to compute a data checksum
// Copyright (C) 2001 Mike Krueger
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
//
// 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 2
// 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, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
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namespace PdfSharp.SharpZipLib.Checksums
{

    /// <summary>
    /// Interface to compute a data checksum used by checked input/output streams.
    /// A data checksum can be updated by one byte or with a byte array. After each
    /// update the value of the current checksum can be returned by calling
    /// <code>getValue</code>. The complete checksum object can also be reset
    /// so it can be used again with new data.
    /// </summary>
    internal interface IChecksum
    {
        /// <summary>
        /// Returns the data checksum computed so far.
        /// </summary>
        long Value
        {
            get;
        }

        /// <summary>
        /// Resets the data checksum as if no update was ever called.
        /// </summary>
        void Reset();

        /// <summary>
        /// Adds one byte to the data checksum.
        /// </summary>
        /// <param name = "value">
        /// the data value to add. The high byte of the int is ignored.
        /// </param>
        void Update(int value);

        /// <summary>
        /// Updates the data checksum with the bytes taken from the array.
        /// </summary>
        /// <param name="buffer">
        /// buffer an array of bytes
        /// </param>
        void Update(byte[] buffer);

        /// <summary>
        /// Adds the byte array to the data checksum.
        /// </summary>
        /// <param name = "buffer">
        /// The buffer which contains the data
        /// </param>
        /// <param name = "offset">
        /// The offset in the buffer where the data starts
        /// </param>
        /// <param name = "count">
        /// the number of data bytes to add.
        /// </param>
        void Update(byte[] buffer, int offset, int count);
    }
}