/*

 *

 * (C) Copyright IBM Corp. 1998-2005 - All Rights Reserved

 *

 */

#ifndef __LESWAPS_H

#define __LESWAPS_H

#include "LETypes.h"

/**

 * \file 

 * \brief C++ API: Endian independent access to data for LayoutEngine

 */

U_NAMESPACE_BEGIN

/**

 * A convenience macro which invokes the swapWord member function

 * from a concise call.

 *

 * @stable ICU 2.8

 */

#if defined(U_IS_BIG_ENDIAN)

    #if U_IS_BIG_ENDIAN

        #define SWAPW(value) (value)

    #else

        #define SWAPW(value) LESwaps::swapWord(value)

    #endif

#else

    #define SWAPW(value) (LESwaps::isBigEndian() ? (value) : LESwaps::swapWord(value))

#endif

/**

 * A convenience macro which invokes the swapLong member function

 * from a concise call.

 *

 * @stable ICU 2.8

 */

#if defined(U_IS_BIG_ENDIAN)

    #if U_IS_BIG_ENDIAN

        #define SWAPL(value) (value)

    #else

        #define SWAPL(value) LESwaps::swapLong(value)

    #endif

#else

    #define SWAPL(value) (LESwaps::isBigEndian() ? (value) : LESwaps::swapLong(value))

#endif

/**

 * This class is used to access data which stored in big endian order

 * regardless of the conventions of the platform. It has been designed

 * to automatically detect the endian-ness of the platform, so that a

 * compilation flag is not needed.

 *

 * All methods are static and inline in an attempt to induce the compiler

 * to do most of the calculations at compile time.

 *

 * @stable ICU 2.8

 */

class U_LAYOUT_API LESwaps /* not : public UObject because all methods are static */ {

public:

#if !defined(U_IS_BIG_ENDIAN)

    /**

     * This method detects the endian-ness of the platform by

     * casting a pointer to a word to a pointer to a byte. On

     * big endian platforms the FF will be in the byte with the

     * lowest address. On little endian platforms, the FF will

     * be in the byte with the highest address.

     *

     * @return TRUE if the platform is big endian

     *

     * @stable ICU 2.8

     */

    static le_uint8 isBigEndian()

    {

        const le_uint16 word = 0xFF00;

        return *((le_uint8 *) &word);

    };

#endif

    /**

     * This method does the byte swap required on little endian platforms

     * to correctly access a (16-bit) word.

     *

     * @param value - the word to be byte swapped

     *

     * @return the byte swapped word

     *

     * @stable ICU 2.8

     */

    static le_uint16 swapWord(le_uint16 value)

    {

        return (((le_uint8) (value >> 8)) | (value << 8));

    };

    /**

     * This method does the byte swapping required on little endian platforms

     * to correctly access a (32-bit) long.

     *

     * @param value - the long to be byte swapped

     *

     * @return the byte swapped long

     *

     * @stable ICU 2.8

     */

    static le_uint32 swapLong(le_uint32 value)

    {

        return swapWord((le_uint16) (value >> 16)) | (swapWord((le_uint16) value) << 16);

    };

private:

    LESwaps() {} // private - forbid instantiation

};

U_NAMESPACE_END

#endif