FixedDatum.h

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/*********************************************************************
Copyright 2013 Karl Jones
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*********************************************************************/

/********************************************************************
    class:      FixedDatum
    created:    18/09/2008
    author:     Karl Jones

    purpose:    Stores fixed datum values.

                                Note: See FactoryDecoder for a guide to adding support 
                                for using your own FixedDatum. 

    size:       64 bits / 8 octets
*********************************************************************/

#pragma once

#include "./DataTypeBase.h"
#include "./FactoryDecoder.h"
#include "./../Extras/KRef_Ptr.h"

namespace KDIS {
namespace DATA_TYPE {

using KDIS::DATA_TYPE::ENUMS::DatumID;
using KDIS::UTILS::IsMachineBigEndian;

/************************************************************************/
// Define the type of pointer we are using for FixedDatum Records,
// do we want a weak reference or a ref counter?
// By default we use a ref pointer, however if you want to use a standard
// pointer or one of your own then simply change it below.
/************************************************************************/
class FixedDatum;
typedef KDIS::UTILS::KRef_Ptr<FixedDatum> FixDtmPtr; // Ref counter
//typedef FixedDatum* FixDtmPtr; // Weak ref

class KDIS_EXPORT FixedDatum : public DataTypeBase, public FactoryDecoderUser<FixedDatum>
{
protected:

    KUINT32 m_ui32DatumID;

    KOCTET m_cDatumValue[4];

public:

    static const KUINT16 FIXED_DATUM_SIZE = 8;

    FixedDatum();

    template<class Type>
    FixedDatum( DatumID ID, Type Value ) throw( KException );

    FixedDatum( KDataStream & stream ) throw( KException );

    virtual ~FixedDatum();

    //************************************
    // FullName:    KDIS::DATA_TYPE::FixedDatum::SetDatumID
    //              KDIS::DATA_TYPE::FixedDatum::GetDatumID
    //!Description: Set the datum id, indicates what the datum value
    //!             is for and what format it should be in.
    // Parameter:   DatumID ID
    //************************************
    virtual void SetDatumID( DatumID ID );
    virtual DatumID GetDatumID() const;

    //************************************
    // FullName:    KDIS::DATA_TYPE::FixedDatum<Type>::SetDatumValue
    //              KDIS::DATA_TYPE::FixedDatum<Type>::GetDatumValue
    //!Description: Returns datum value in required format, format
    //!             must be 32 bits or less.
    // Parameter:   Type val
    //************************************
    template<class Type>
    void SetDatumValue( Type val ) throw( KException );
    template<class Type>
    Type GetDatumValue() const throw( KException );

    //************************************
    // FullName:    KDIS::DATA_TYPE::FixedDatum::GetDatumValue
    //!Description: Copies octets into a buffer.
    //!             Buffer must be 4 octets in size.
    //!             All data types are stored in Big Endian
    //!             in the buffer.
    // Parameter:   KOCTET * Buffer
    //************************************
    virtual void GetDatumValue( KOCTET * Buffer, KUINT16 BufferSize ) const throw( KException );

    //************************************
    // FullName:    KDIS::DATA_TYPE::FixedDatum::GetAsString
    //!Description: Returns a string representation
    //************************************
    virtual KString GetAsString() const;

    //************************************
    // FullName:    KDIS::DATA_TYPE::FixedDatum::Decode
    //!Description: Convert From Network Data.
    // Parameter:   KDataStream & stream
    //************************************
    virtual void Decode( KDataStream & stream ) throw( KException );

    //************************************
    // FullName:    KDIS::DATA_TYPE::FixedDatum::Encode
    //!Description: Convert To Network Data.
    // Parameter:   KDataStream & stream
    //************************************
    virtual KDataStream Encode() const;
    virtual void Encode( KDataStream & stream ) const;

    KBOOL operator == ( const FixedDatum & Value ) const;
    KBOOL operator != ( const FixedDatum & Value ) const;
};

/////////////////////////////////////////////////////////////////////////
// templates
//////////////////////////////////////////////////////////////////////////

template<class Type>
FixedDatum::FixedDatum( DatumID ID, Type Value ) throw( KException )
{
    m_ui32DatumID = ID;
    SetDatumValue( Value );
}

//////////////////////////////////////////////////////////////////////////

template<class Type>
Type FixedDatum::GetDatumValue() const throw( KException )
{
    if( sizeof( Type ) > 4 )throw KException( __FUNCTION__, DATA_TYPE_TOO_LARGE );

    NetToDataType<Type> NetValue( m_cDatumValue, false );

    // Do we need to convert the data back to machine endian?
    if( IsMachineBigEndian() == false )
    {
        // Need to convert
        NetValue.SwapBytes();
    }

    return NetValue.m_Value;
}

//////////////////////////////////////////////////////////////////////////

template<class Type>
void FixedDatum::SetDatumValue( Type val ) throw( KException )
{
    if( sizeof( Type ) > 4 )throw KException( __FUNCTION__, DATA_TYPE_TOO_LARGE );

    // Reset datum value.
    memset( m_cDatumValue, 0x00, 4 );

    NetToDataType<Type> NetValue( val, false );

    // Now convert the data into big endian, we want to store the value like this
    // as when we encode/decode we have no way to know what the data type is or how many
    // octets long it is. We only convert to machine endian when the data is requested.
    if( IsMachineBigEndian() == false )
    {
        // Need to convert
        NetValue.SwapBytes();
    }

    // Copy into datum value.
    for( KUINT16 i = 0; i < sizeof( Type ); ++i )
    {
        m_cDatumValue[i] = NetValue.m_Octs[i];
    }
}

//////////////////////////////////////////////////////////////////////////

} // END namespace DATA_TYPES
} // END namespace KDIS