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//

// Checksum.h

//

// $Id: //poco/1.3/Foundation/include/Poco/Checksum.h#1 $

//

// Library: Foundation

// Package: Core

// Module:  Checksum

//

// Definition of the Checksum class.

//

// Copyright (c) 2007, Applied Informatics Software Engineering GmbH.

// and Contributors.

//

// Permission is hereby granted, free of charge, to any person or organization

// obtaining a copy of the software and accompanying documentation covered by

// this license (the "Software") to use, reproduce, display, distribute,

// execute, and transmit the Software, and to prepare derivative works of the

// Software, and to permit third-parties to whom the Software is furnished to

// do so, all subject to the following:

//

// The copyright notices in the Software and this entire statement, including

// the above license grant, this restriction and the following disclaimer,

// must be included in all copies of the Software, in whole or in part, and

// all derivative works of the Software, unless such copies or derivative

// works are solely in the form of machine-executable object code generated by

// a source language processor.

//

// 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, TITLE AND NON-INFRINGEMENT. IN NO EVENT

// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE

// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,

// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

// DEALINGS IN THE SOFTWARE.

//

#ifndef Foundation_Checksum_INCLUDED

#define Foundation_Checksum_INCLUDED

#include "Poco/Foundation.h"

namespace Poco {

class Foundation_API Checksum

        /// This class calculates CRC-32 or Adler-32 checksums

        /// for arbitrary data.

        ///

        /// A cyclic redundancy check (CRC) is a type of hash function, which is used to produce a

        /// small, fixed-size checksum of a larger block of data, such as a packet of network

        /// traffic or a computer file. CRC-32 is one of the most commonly used CRC algorithms.

        ///

        /// Adler-32 is a checksum algorithm which was invented by Mark Adler.

        /// It is almost as reliable as a 32-bit cyclic redundancy check for protecting against

        /// accidental modification of data, such as distortions occurring during a transmission,

        /// but is significantly faster to calculate in software.

{

public:

        enum Type

        {

                TYPE_ADLER32 = 0,

                TYPE_CRC32

        };

        Checksum();

                /// Creates a CRC-32 checksum initialized to 0.

        Checksum(Type t);

                /// Creates the Checksum, using the given type.

        ~Checksum();

                /// Destroys the Checksum.

        void update(const char* data, unsigned length);

                /// Updates the checksum with the given data.

        void update(const std::string& data);

                /// Updates the checksum with the given data.

        void update(char data);

                /// Updates the checksum with the given data.

        Poco::UInt32 checksum() const;

                /// Returns the calculated checksum.

        Type type() const;

                /// Which type of checksum are we calulcating

private:

        Type         _type;

        Poco::UInt32 _value;

};

//

// inlines

//

inline void Checksum::update(const std::string& data)

{

        update(data.c_str(), static_cast<unsigned int>(data.size()));

}

inline void Checksum::update(char c)

{

        update(&c, 1);

}

inline Poco::UInt32 Checksum::checksum() const

{

        return _value;

}

inline Checksum::Type Checksum::type() const

{

        return _type;

}

} // namespace Poco

#endif // Foundation_Checksum_INCLUDED