littobig.h

著名的 helix realplayer 基于手机 symbian 系统的 播放器全套源代码

/* ***** BEGIN LICENSE BLOCK ***** 
 * Version: RCSL 1.0/RPSL 1.0 
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 * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved. 
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 * (the "RCSL") available at http://www.helixcommunity.org/content/rcsl, 
 * in which case the RCSL will apply. You may also obtain the license terms 
 * directly from RealNetworks.  You may not use this file except in 
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 * This file is part of the Helix DNA Technology. RealNetworks is the 
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/*

	CLittleEndianToBigEndian

	This class supports functions for converting data from LittleEndian byte order to 
	BigEndian byte order.

	This is different from using NetByte and HostByte order, becuase using the NetToHost fucntion 
	would not work on LittleEndian machines, as they are considered NetByte in the first place.

*/


#ifndef _CLITTOBIG_H
#define _CLITTOBIG_H

#include "hxtypes.h"

// GR 5/10/02 The old version of this class does a runtime test for endianness,
// and makes function calls to maybe swap the bytes.  None of that should really
// be necessary.  
//
// I'm only checking in a new version for Mac since that's all I can test on right now, 
// though the second inline version below for little-endian ought to work, too, and makes
// sense to use for Windows.

#if defined(_BIG_ENDIAN)

#define CLittleEndianToBigEndian_INLINE 1

class	CLittleEndianToBigEndian
{
  public:
    
    static inline	BOOL	TestBigEndian() { return TRUE; }
    
    static inline	void	ReverseWORD(UINT16& w) 
	{ 	
	    w = (((((UINT16) w)<<8) & 0xFF00) 
		 | ((((UINT16) w)>>8) & 0x00FF)); 
	}
    static inline	void	ReverseDWORD(ULONG32& w)
	{
	    w = (((((UINT32) w)<<24) & 0xFF000000)  | 
		 ((((UINT32) w)<< 8) & 0x00FF0000)  | 
		 ((((UINT32) w)>> 8) & 0x0000FF00)  | 
		 ((((UINT32) w)>>24) & 0x000000FF));
	}


};

#elif defined(_LITTLE_ENDIAN)

#define CLittleEndianToBigEndian_INLINE 1

class	CLittleEndianToBigEndian
{
  public:
    static inline	BOOL	TestBigEndian() { return FALSE; }
    
    static inline	void	ReverseWORD(UINT16& w) {}
    static inline	void	ReverseDWORD(ULONG32& w) {}
};


#else
// This is the old one which compiles to run-time tests of endianness, 
// which probably shouldn't needed for any platform

class	CLittleEndianToBigEndian
{
public:
	
	static	void	ReverseWORD(UINT16& w);
	static	void	ReverseDWORD(ULONG32& w);

	static	BOOL	TestBigEndian();

private:
	static	BOOL	mBigEndian;
	static	BOOL	mInitialized;
	
};

#endif



#endif // _CLITTOBIG_H